text:
US 6757811 B1 Abstract A simultaneous and redundantly threaded, pipelined processor can execute the same set of instructions simultaneously as two separate threads to provide, for example, fault tolerance. One thread is processed ahead of the other thread thereby creating a �slack� between the two threads so that the instructions in one thread are processed through the processor's pipeline ahead of the corresponding instructions from the other thread. The thread, whose instructions are processed earlier, is called the �leading� thread. The other thread is the �trailing� thread. By setting the amount of slack appropriately, all or at least some of the cache misses or branch misspeculations encountered by the trailing thread can be resolved by the time the corresponding instructions from the trailing thread are fetched and processed through the pipeline. The invention, therefore, improves the performance of a fault tolerant, simultaneous and redundantly threaded processor.
Claims(25) 1. A computer system, comprising:
a pipelined, simultaneous and redundantly threaded (SRT) processor;
an I/O controller coupled to said processor;
an I/O device coupled to said I/O controller; and
an main system memory coupled to said processor;
wherein said SRT processor processes a set of instructions in a leading thread and also in a trailing thread, and wherein the instructions in the trailing thread are substantially identical to the instructions in the leading thread, and wherein by action of a slack counter, the instructions in the trailing thread beginning processing through the processor after the corresponding instructions in the leading thread begin processing through the processor.
2. The computer system of
3. The computer system of
4. The computer system of
5. The computer system of
6. The computer system of
7. The computer system of
8. The computer system of
9. The computer system of
10. The computer system of
11. A pipelined, simultaneous and redundantly threaded (SRT) processor, comprising:
a fetch unit that fetches instructions from a plurality of threads of instructions;
an instruction cache coupled to said fetch unit and storing instructions to be decoded and executed; and
decode logic coupled to said instruction cache to decode the type of instructions stored in said instruction cache;
wherein said processor processes a set of instructions in a leading thread and also in a trailing thread, and wherein the instructions in the trailing thread are substantially identical to the instructions in the leading thread; and
wherein, via a slack counter, the instructions in the trailing thread begin processing through the processor after the corresponding instructions in the leading thread begin processing through the processor.
12. The SRT processor of
13. The SRT processor of
14. The SRT processor of
15. The SRT processor of
16. The SRT processor of
17. The SRT processor of
18. The SRT processor of
19. The SRT processor of
20. The SRT processor of
21. A method of fetching instructions in an SRT processor which can fetch and execute a set of instructions in two separate threads so that each thread includes substantially the same instructions as the other thread, one of said threads being a leading thread and the other of said threads being a trailing thread, the method comprising:
initializing a slack counter having an output count value to a target slack value that represents a number of instructions of separation between corresponding instructions in the leading and trailing threads;
decrementing said slack counter when the leading thread commits an instruction;
incrementing said slack counter when the trailing thread commits an instruction;
adding the output count value from the slack counter to a program count value of a program counter associated with the trailing thread to produce a sum; and
fetching an instruction from the leading thread if the difference between the sum and a program count value of a program counter associated with the leading thread is less than the target slack.
22. The method of
23. The method of
24. An electronic system, comprising:
a pipelined, simultaneous and redundantly threaded (SRT) processor, and
an main system memory coupled to said processor;
wherein said SRT processor processes a set of instructions in a leading thread and also in a trailing thread, and wherein the instructions in the trailing thread are substantially identical to the instructions in the leading thread, and wherein by action of a counter, the instructions in the trailing thread are delayed from processing through the processor relative to corresponding instructions in the leading thread.
25. The electronic system of
Description This application is a non-provisional application claiming priority to U.S. provisional application Serial No. 60/198,530 filed on Apr. 19, 2000, entitled �Transient Fault Detection Via Simultaneous Multithreading,� the teachings of which are incorporated by reference herein. Not applicable. 1. Field of the Invention The present invention generally relates to microprocessors. More particularly, the present invention relates to a pipelined, multithreaded processor that can process the same instruction set in at least two separate threads. More particularly still, the invention relates to imposing �slack� between corresponding instructions in the threads of a multithreaded processor to improve the processor's performance. 2. Background of the Invention Solid state electronics, such as microprocessors, are susceptible to transient hardware faults. For example, cosmic rays can alter the voltage levels that represent data values in microprocessors, which typically include tens or hundreds of thousands of transistors. Cosmic radiation can change the state of individual transistors causing faulty operation. Faults caused by cosmic radiation typically are temporary and the transistors eventually switch back to their normal state. The frequency of such transient faults is relatively low�typically less than one fault per year per thousand computers. Because of this relatively low failure rate, making computers fault tolerant currently is attractive more for mission-critical applications, such as online transaction processing and the space program, than computers used by average consumers. However, future microprocessors will be more prone to transient fault due to their smaller anticipated size, reduced voltage levels, higher transistor count, and reduced noise margins. Accordingly, even low-end personal computers may benefit from being able to protect against such faults. One way to protect solid state electronics from faults resulting from cosmic radiation is to surround the potentially effected electronics by a sufficient amount of concrete. It has been calculated that the energy flux of the cosmic rays can be reduced to acceptable levels with six feet or more of concrete surrounding the computer containing the chips to be protected. For obvious reasons, protecting electronics from faults caused by cosmic ray with six feet of concrete usually is not feasible. Further, computers usually are placed in buildings that have already been constructed without this amount of concrete. Other techniques for protecting microprocessors from faults created by cosmic radiation also have been suggested or implemented. Rather than attempting to create an impenetrable barrier through which cosmic rays cannot pierce, it is generally more economically feasible and otherwise more desirable to provide the effected electronics with a way to detect and recover from a fault caused by cosmic radiation. In this manner, a cosmic ray may still impact the device and cause a fault, but the device or system in which the device resides can detect and recover from the fault. This disclosure focuses on enabling microprocessors (referred to throughout this disclosure simply as �processors�) to recover from a fault condition. One technique, such as that implemented in the Compaq Himalaya system, includes two identical �lockstepped� microprocessors. Lockstepped processors have their clock cycles synchronized and both processors are provided with identical inputs (i.e., the same instructions to execute, the same data, etc.). A checker circuit compares the processors' data output (which may also include memory addressed for store instructions). The output data from the two processors should be identical because the processors are processing the same data using the same instructions, unless of course a fault exists. If an output data mismatch occurs, the checker circuit flags an error and initiates a software or hardware recovery sequence. Thus, if one processor has been affected by a cosmically-created fault, its output likely will differ from that of the other synchronized processor. Although lockstepped processors are generally satisfactory for creating a fault tolerant environment, implementing fault tolerance with two processors takes up valuable real estate. A pipelined, simultaneous multithreaded, out-of-order processor generally can be lockstepped. A �pipelined� processor includes a series of functional units (e.g., fetch unit, decode unit, execution units, etc.), arranged so that several units can be simultaneously processing an appropriate part of several instructions. Thus, while one instruction is being decoded, an earlier fetched instruction can be executed. A �simultaneous multithreaded� (�SMT�) processor permits instructions from two or more different program threads (e.g., applications) to be processed through the processor simultaneously. An �out-of-order� processor permits instructions to be processed in an order that is different than the order in which the instructions are provided in the program (referred to as �program order�). Out-of-order processing potentially increases the throughput efficiency of the processor. Accordingly, an SMT processor can process two programs simultaneously. It is generally possible to cycle lock step on SMT processor. An SMT processor can be modified so that the same program is simultaneously executed in two separate threads to provide fault tolerance within a single processor. Such a processor is called a simultaneously and redundantly threaded (�SRT�) processor. Some of the modifications to turn a SMT processor into an SRT processor are described in U.S. Provisional Application Serial No. 60/198,530. Executing the same program in two different threads permits the processor to detect faults such as may be caused by cosmic radiation, noted above. By comparing the output data from the two threads at appropriate times and locations within the SRT processor, it is possible to detect whether a fault has occurred. For example, data written to cache memory or registers that should be identical from corresponding instructions in the two threads can be compared. If the output data matches, there is no fault. Alternatively, if there is a mismatch in the output data, a fault has occurred in one or both of the threads. Executing the same program in two separate threads advantageously affords the SRT processor some degree of fault tolerance, but also may cause several performance problems. For instance, any latency caused by a cache miss is exacerbated. Cache misses occur when an instruction requests data from memory that is not also available in cache memory. The processor first checks whether the requested data already resides in the faster access cache memory, which generally is onboard the processor die. If the requested data is not present in cache (a condition referred to as a cache �miss�), then the processor is forced to retrieve the data from main system memory which takes more time, thereby causing latency, than if the data could have been retrieved from the faster onboard cache. Because the two threads are executing the same instructions, any instruction in one thread that results in a cache miss will also experience the same cache miss when that same instruction is executed in other thread. That is, the cache latency will be present in both threads. A second performance problem concerns branch misspeculation. A branch instruction requires program execution either to continue with the instruction immediately following the branch instruction if a certain condition is met, or branch to a different instruction if the particular condition is not met. Accordingly, the outcome of a branch instruction is not known until the instruction is executed. In a pipelined architecture, a branch instruction (or any instruction for that matter) may not be executed for at least several, and perhaps many, clock cycles after the branch instruction is fetched by the fetch unit in the processor. In order to keep the pipeline full (which is desirable for efficient operation), a pipelined processor includes branch prediction logic which predicts the outcome of a branch instruction before it is actually executed (also referred to as �speculating�). Branch prediction logic generally bases its speculation on short or long term history. As such, using branch prediction logic, a processor's fetch unit can speculate the outcome of a branch instruction before it is actually executed. The speculation, however, may or may not turn out to be accurate. That is, the branch predictor logic may guess wrong regarding the direction of program execution following a branch instruction. If the speculation proves to have been accurate, which is determined when the branch instruction is executed by the processor, then the next instructions to be executed have already been fetched and are working their way through the pipeline. If, however, the branch speculation turns out to have been the wrong prediction (referred to as �misspeculation�), many or all of the instructions filling the pipeline behind the branch instruction may have to be thrown out (i.e., not executed) because they are not the correct instructions to be executed after the branch instruction. The result is a substantial performance hit as the fetch unit must fetch the correct instructions to be processed through the pipeline. Suitable branch prediction methods, however, result in correct speculations more often than misspeculations and the overall performance of the processor is improved with a suitable branch predictor (even in the face of some misspeculations) than if no speculation was available at all. In an SRT processor that executes the same program in two different threads for fault tolerance, any branch misspeculation is exacerbated because both threads will experience the same misspeculation. Because, the branch misspeculation occurs in both threads, the processor's internal resources usable to each thread are wasted while the wrong instructions are replaced with the correct instructions. Of course, it is always desirable to improve the efficiency in a processor. Accordingly, any increase in efficiency, and thus speed, of an SRT processor is highly desirable. Similarly, improvements in the efficiency of a simultaneous multithreaded processor capable of executing the same instruction set as two separate threads for fault tolerance also is desirable. The problems noted above are solved in large part by a simultaneous and redundantly threaded processor that can simultaneously execute the same program in two separate threads to provide fault tolerance. By simultaneously executing the same program twice, the system can be made fault tolerant by checking the output data pertaining to corresponding instructions in the threads to ensure that the data matches. A data mismatch indicates a fault in the processor effecting one or both of the threads. The preferred embodiment of the invention provides an increase in performance to such a fault tolerant, simultaneous and redundantly threaded processor. In accordance with the preferred embodiment of the invention, one thread is processed ahead of the other thread thereby creating a �slack� of instructions between the two threads so that the instructions in one thread are processed through the processor's pipeline ahead of the corresponding instructions from the other thread. The thread, whose instructions are processed earlier, is called the �leading� thread, while the other thread is the �trailing� thread. By setting the amount of slack (in terms of numbers of instructions) appropriately, all or at least some of the cache misses or branch misspeculations encountered by the leading thread can be resolved before the corresponding instructions from the trailing thread are fetched and processed through the pipeline. A cache miss in the leading thread resulting, for example, from a store instruction will cause the requested data to be stored in the cache. Then, when the same store instruction in the trailing thread is processed, the requested data will already reside in cache and no cache miss in the trailing thread will occur, thereby reducing latency. Similarly, any branch misspeculation in the leading thread will not occur in the trailing thread because the branch instruction will have been resolved in the leading thread by the time that same instruction is fetched in the trailing thread. The amount of slack preferably is programmable. Programming more slack into the system provides the leading thread a chance to bring data into the cache and resolve branch misspeculations before the corresponding instructions in the trailing thread are processed through the processor's pipeline. However, excessively long slacks can reduce system performance. A desirable amount of slack will vary from system to system and application to application. A slack of 256 instructions, for example, has been found to significantly improve system performance. For a detailed description of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which: FIG. 1 is a diagram of a computer system constructed in accordance with the preferred embodiment of the invention and including a simultaneous and redundantly threaded processor; FIG. 2 is a block diagram of the simultaneous and redundantly threaded processor from FIG. 1 in accordance with the preferred embodiment that includes a slack counter that maintains a slack of instructions between at least two threads; and FIG. 3 conceptually illustrates the performance benefit achieved by the multithreaded processor of FIGS. 1 and 2 from its ability to simultaneously execute two threads containing the same instruction set but with one thread trailing the other thread. Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, microprocessor companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms �including� and �comprising� are used in an open-ended fashion, and thus should be interpreted to mean �including, but not limited to . . . �. Also, the term �couple� or �couples� is intended to mean either an indirect or direct electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. The term �slack� is intended to mean the number of instructions that one thread is ahead of another thread that is executing the same instruction set. For example, a slack of 256 instructions means that the processor will give one thread a 256 instruction �head start� over another thread having the same instruction set in terms of fetching instructions. Accordingly, the processor will not fetch the first instruction from the delayed thread until the processor has fetched the 256th instruction from the leading thread. FIG. 1 shows a computer system 90 including a pipelined, simultaneous and redundantly threaded (�SRT�) processor 100 constructed in accordance with the preferred embodiment of the invention. Besides processor 100, computer system 90 also includes dynamic random access memory (�DRAM�) 92, an input/output (�I/O�) controller 93, and various I/O devices which may include a floppy drive 94, a hard drive 95, a keyboard 96, and the like. The I/O controller 93 provides an interface between processor 100 and the various I/O devices 94-96. The DRAM 92 can be any suitable type of memory devices such as RAMBUS� memory. In addition, SRT processor 100 may also be coupled to other SRT processors if desired in a commonly known �Manhattan� grid, or other suitable architecture. FIG. 2 shows the SRT processor 100 of FIG. 1 in greater detail. Referring to FIG. 2, processor 100 preferably comprises a pipelined architecture which includes a series of functional units, arranged so that several units can be simultaneously processing appropriate part of several instructions. As shown, the exemplary embodiment of processor 100 includes a fetch unit 104, one or more program counters 106, an instruction cache 110, decode logic 114, register rename logic 118, floating point and integer registers 122, 126, a register update unit 130, execution units 134, 138, and 142, and a data cache 146. Fetch unit 102 uses a program counter 106 for assistance as to which instruction to fetch. Being a multithreaded processor, the fetch unit 102 preferably can simultaneously fetch instructions from multiple threads. A separate program counter 106 is associated with each thread. Each program counter 106 is a register that contains the address of the next instruction to be fetched from the corresponding thread by the fetch unit 102. FIG. 2 shows two program counters 106 to permit the simultaneous fetching of instructions from two threads. It should be recognized, however, that additional program counters can be provided to fetch instructions from more than two threads simultaneously. As shown, fetch unit 102 includes branch prediction logic 103 and a �slack� counter 104. The slack counter 104 will be described in greater detail below. The branch prediction logic 104 permits the fetch unit 102 to speculate ahead on branch instructions as noted above. In order to keep the pipeline full (which is desirable for efficient operation), the branch predictor logic 103 speculates the outcome of a branch instruction before the branch instruction is actually executed. Branch predictor 103 generally bases its speculation on previous instructions. Any suitable speculation algorithm can be used in branch predictor 103. Referring still to FIG. 2, instruction cache 110 provides a temporary storage buffer for the instructions to be executed. Decode logic 114 retrieves the instructions from instruction cache 110 and determines the type of each instruction (e.g., add, subtract, load, store, etc.). Decoded instructions are then passed to the register rename logic 118 which maps logical registers onto a pool of physical registers. The register update unit (RUU) 130 provides an instruction queue for the instructions to be executed. The RUU 130 serves as a combination of global reservation station pool, rename register file, and reorder buffer. The RUU 130 breaks load and store instructions into an address portion and a memory (i.e., register) reference. The address portion is placed in the RUU 130, while the memory reference portion is placed into a load/store queue (not specifically shown in FIG. 2). The floating point register 122 and integer register 126 are used for the execution of instructions that require the use of such registers as is known by those of ordinary skill in the art. These registers 122, 126 can be loaded with data from the data cache 146. The registers also provide their contents to the RUU 130. As shown, the execution units 134, 138, and 142 comprise a floating point execution unit 134, a load/store execution unit 138, and an integer execution unit 142. Each execution unit performs the operation specified by the corresponding instruction type. Accordingly, the floating point execution units 134 execute floating instructions such as multiply and divide instruction while the integer execution units 142 execute integer-based instructions. The load/store units 138 perform load operations in which data from memory is loaded into a register 122 or 126. The load/store units 138 also perform store operations in which data from registers 122, 126 is written to data cache 146 and/or DRAM memory 92 (FIG. 1). The architecture and components described herein are typical of microprocessors, and particularly pipelined, multithreaded processors. Numerous modifications can be made from that shown in FIG. 2. For example, the locations of the RUU 130 and registers 122, 126 can be reversed if desired. For additional information, the following references, all of which are incorporated herein by reference, may be consulted for additional information if needed: U.S. patent application Ser. No. 08/775,553, filed Dec. 31, 1996. and �Exploiting Choice: now U.S. Pat. No. 6,073,159 issued on Jun. 6, 2000. Instruction Fetch and Issue on an Implementable Simultaneous Multithreaded Processor,� by D. Tullsen, S. Eggers, J. Emer, H. Levy, J. Lo and R. Stamm, Proceedings of the 23rd Annual International Symposium on Computer Architecture, Philadelphia, Pa., May 1996. The preferred embodiment of the invention provides a performance enhancement to SRT processors. The preferred SRT processor 100 described above is capable of processing instructions from two different threads simultaneously. Such a processor in fact can be made to execute the same program as two different threads. In other words, the two threads contain the same exact set of program. Processing the same program through the processor in two different threads permits the processor to detect faults caused by cosmic radiation as noted above. The disadvantage of such a fault tolerant processor is that cache misses and branch misspeculations cause performance problems as noted above. The preferred embodiment of the invention solves these problems thereby providing a substantial performance increase in an SRT processor. Referring still to FIG. 2, fetch unit 102 preferably includes a �slack� counter 104. Slack counter 104 is used to create a delay of a desired number of instructions between the two threads including the same instruction set. The delay is referred to herein as a �slack.� The description of and advantage of the slack will now be explained with reference to FIG. 3 followed by a discussion of how the slack counter 104 is used to create the slack. FIG. 3 shows a single program that is copied by fetch unit 102 (FIG. 2) into two threads�thread T0 and thread T1. Both threads include instructions A-L as shown, and perhaps more. Thread T0 is arbitrarily designated as the �leading� thread while thread T1 is designated as the �trailing� thread. As shown in the conceptual drawing of FIG. 3, the instructions in trailing thread T1 begin their way through the pipeline of processor 100 six instructions behind or after leading thread T0. Thus, while processor 100 begins fetching and processing instructions A, B, C, etc. from leading thread T0, the fetch unit 102 of processor 100 will not begin fetching instruction A from the trailing thread T1 until the fetch unit 102 has already fetched the first six instructions from the leading thread. As explained below, the slack advantageously provides a substantial performance improvement to the multithreaded processor art. Referring to FIGS. 2 and 3, once a branch instruction has executed in an execution unit 134, 138, 142, a register 105 in the branch predictor logic 103 is updated with the correct result of the branch. Thus, register 105 will indicate the correct direction of program execution following the branch instruction. Because of the slack between the two threads, some or all branch instructions in the leading thread preferably will be resolved before the corresponding branch instructions from the trailing thread T1 are fetched. When fetching a branch instruction from the trailing thread, the fetch unit preferably probes the register 105 in the branch predictor logic 103 to determine if that particular branch instruction from the leading thread has already been fetched and resolved. If so, branch speculation is unnecessary for the branch instruction in the trailing thread�the leading thread has already determined the next instruction to execute after the branch instruction. As such, speculation of trailing thread branch instructions generally is unnecessary because the correct outcome of the branch instruction will already be known from its execution in the leading thread. Accordingly, the latency caused by branch misspeculation is avoided in the trailing thread. Similarly, because of the slack cache misses can be avoided in the trailing thread. Some or all cache misses in the leading thread will result in the requested data being written to the processor's data cache 146. When that same instruction is processed in the trailing thread, the requested data will already be present in data cache 146 thereby a cache miss in the trailing thread and eliminating the latency such a cache miss would have caused. In short, the introduction of slack permits the leading thread to resolve all or most branch misspeculations and cache misses so that the corresponding instructions in the trailing thread will not experience the same latency problems. Thus, the introduction of slack into the simultaneous multithreaded operation achieves at least two performance benefits�reducing the frequency of cache misses and branch misspeculations in the trailing thread. The use of the slack counter 104 to create the instruction slack between the leading and trailing threads will now be described. The slack counter 104 preferably is a signed counter that is decremented when the leading thread T0 commits an instruction (�committing� an instruction refers to the process of completing the execution of and retiring an instruction). Further, the counter is incremented when the trailing thread commits an instruction. The counter 104 preferably is initialized at system reset to the target slack. The fetch policy implemented by the fetch unit 102 preferably is to give priority to the thread that generally has the fewest number of instructions in the instruction cache 110, decode 114, and register rename 118. This fetch policy can be implemented by fetching instructions from the thread whose program counter 106 has a lower value than the other program counter associated with the other thread. More specifically, the fetch policy is implemented by adding the count value of slack counter 104 to the program counter value associated with the trailing thread and comparing that sum to the program counter value of the leading thread. By adding the count value of slack counter 104 in each cycle to the trailing thread's program count, the fetch policy will favor the leading thread (i.e., fetch instructions from the leading thread) until the target slack is reached. This process automatically guides the fetch unit 102 to maintain the desired instruction slack. The amount of slack in the example of FIG. 3 is six instructions. In general, the amount of slack can be any desired number of instructions. For example, as shown in U.S. Provisional patent application 60/198,530 filed on Apr. 19, 2000, a slack of 256 instructions was shown to provide a 10% performance increase. The amount of slack can be preset or programmable by the user of computer system 90 and preferably is large enough to permit the leading thread to resolve some, most, or all cache misses and branch misspeculations before the corresponding instructions from the trailing thread are executed. It will also be understood by one of ordinary skill in the art that, in certain situations, the two threads will have to synchronized thereby reducing the slack to zero. Examples of such situations include uncached loads and external interrupts. Accordingly, the preferred embodiment of the invention provides a significant performance increase of an SRT processor that can execute the same instruction set in two different threads. The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications. Patent Citations
Non-Patent Citations
Referenced by
Legal Events
Rotate |


text:
Jun 23 natural-aura: Follow for Boho ☼ Hippie ☮ Nature εїз(Source: hotstaff, via natural-aura-deactivated2013031)
Jun 15 natural-aura: Boho ☼ Hippie ☮ Nature εїз(Source: asukanyan, via natural-aura-deactivated2013031)
Jun 14 serpentpriest: These are the characteristics of your Third Eye Chakra depending on your energy state: Excessive: Hallucination, nightmares, obsessions, delusions, difficulty concentrating, headaches Deficient: Poor vision and memory, insensitivity, lack of imagination, difficulty visualizing, difficulty seeing the future, can't remember dreams, denial Balanced: Intuitive, perceptive, imaginative, good memory, able to visualize, able to think symbolically, able to remember dreams Track 6 of The Way of the Serpent, is a 10-minute meditation aid that tunes into the sacred frequency of 288Hz to restore balance into your third eye chakra and activate your full potential. To produce its beneficial effects, this binaural audio track has a base frequency of 7.83Hz, which is the Earth's fundamental magnetic resonance frequency. You can download now the full set of The Way of the Serpent which includes 20-minute tracks tuned to each of the main seven chakras plus two versions of the ascension meditations.

subset: commoncrawl


text:
They're All in Their Underwear: Public speaking tips
- Arrive early so you don't feel rushed.
- Don't let negative thoughts play over and over in your head. Think to yourself how prepared you are and how you practiced and you'll do great.
- Relax. Try focusing on relaxing your muscles every time you breathe out. Picture the muscles loosening with each exhale.
- Have a glass of water in case your mouth goes dry or you need a moment to think.
- Look at smiling faces or the faces of friends when you're speaking. If even these people make you nervous, then look at the top of the audience's heads instead of their eyes.
- And don't forget to imagine your audience in their underwear.
Next time it's your turn to present something or just lead the weekly staff meeting, use these tips to get your point across more effectively and make the experience enjoyable for you and your audience. The more you do it, the easier it will get and that could help you further your career.
- « Previous Page
- 1
- 2
- Next Page »
We Recommend
Public Speaking
How to eliminate the fear
Take the elevator to success
Maintenance Matters Take the Elevator to Success Communicate the details and key benefits By Fred Workley The problem is "failure to communicate." Some time ago, I was in a repair...
Not So Lethal Weapons
Not So Lethal Weapons Common sense for power tool safety By Michelle Garetson June 1999 While I don't doubt Mel Gibson's prowess as an actor, I would be leery of casting him in...
Where Am I Going and How Do I Get There?
Advances in our career will happen in one of two ways: by default or by design


text:
How we change what others think, feel, believe and do |
Parrhesia Techniques > Use of language > Figures of speech > Parrhesia Method | Example | Discussion | See also DescriptionParrhesia is speaking boldly and candidly. ExampleIt is true! The king has lost his mind and we must act to save the kingdom. I have no idea what you are saying. You are talking nonsense, just to fill the space in front of you. DiscussionWhen a person speaks as if something is true or important, then others are more likely to believe them. In contrast, if we are hesitant and use uncertain language, then others are less likely to believe us. When spoken well, then this is assertiveness, when done badly, it can seem like aggression. Speaking freely requires either boldness or trust or both. In many societies there are many rules about 'saving face' for others and behaving with dignity. In others, speaking the truth can get you arrested. In Greek, parrhesia means not only to speak freely, but also to speak boldly and even be obliged to tell truth for the common good. Courage is thus saying what must be said, even when it may be lead to personal harm. Classification: Amplification See also |
— Contact — Caveat — About — Students — Webmasters — Awards — Guestbook — Feedback — Sitemap — Changes — |
| ||||||


text:
US 20040030262 A1 Abstract A tissue marker formed of a biodegradable polymer having drug-delivery capabilities is combined with a sealant that encapsulates the tissue marker and which serves to help anchor the tissue marker against migration. The sealant is delivered to a site in dehydrated form and moisture inherent in tissue at the site expands the sealant. The expanded sealant is formed of a hydrogel and is therefore more compatible to the surrounding tissue than the material of the tissue marker. The sealant and the tissue marker are both bioabsorbed over time.
Claims(49) 1. A combination tissue marker polymer and sealant, wherein said tissue marker polymer is formed of a biodegradable polymer and wherein said sealant encapsulates the tissue marker polymer and anchors the tissue marker against migration.
2. The combination of
3. The combination of
4. The combination of
5. The combination of
6. The combination of
7. The combination of
8. The combination of
9. The combination of
10. The combination of
11. The combination of
12. The combination of
13. The combination of
14. The combination of
15. A method for anchoring an implant at a specific site, comprising the steps of encapsulating a polymer selected from a group of polymers consisting of poly (dioxanone), polyethylene glycol, hydrogels, polylactides, polyglycolides, polycaprolactone, and their copolymers within a hydrogel.
16. The method of
17. The method of
18. The method of
19. The method of
20. The method of
21. The method of
22. The method of
23. The method of
24. The method of
25. The method of
26. The method of
27. The method of
28. A method for fabricating tubular implants for implanting in tubular organs, comprising the step of forming a lumen defined by a polymer selected from a group of polymers consisting of poly(dioxanone), polyethylene glycol. hydrogels, polylactides, polyglycolides, polycaprolactone, and their copolymers and a hydrogel that provides the exterior of the implant so that as the hydrogel expands upon contact with a liquid fluid, it anchors itself into the surrounding tissue.
29. The method of
30. A method for controlling the degradation rate of a tissue marker polymer, comprising the steps of employing a biodegradable hydrophobic polymer coating to delay the penetration into the substrate by water or other bodily fluid.
31. The method of
32. The method of
33. The method of
34. A method for performing a hepatic biopsy, comprising the steps of forming a bore in a liver by a biopsy procedure, providing a plug formed of an expandable sealant material, and sealing said bore at its surface with said plug to prevent bleeding, said plug expanding to securely seal the opening when contacted by bodily moisture.
35. The method of
36. The method of
37. A method for performing an angioplasty procedure, comprising the steps of positioning a non-hydrated hydrogel sealant, in tubular form, within a lumen of an artery, said sealant expanding upon contact with natural body moisture present in said artery to hold the artery open.
38. The method of
39. A method for performing an angioplasty procedure, comprising the steps of providing an expandable sealant material in annular form and positioning a plurality of said annular sealant materials in annular form in longitudinally and equidistantly spaced relation to one another along the extent of an expanded section of artery, in transverse relation to the longitudinal axis of the artery.
40. The method of
41. The method of
42. The method of
43. A method for treating BHP, comprising the steps of surgically removing a preselected part of a prostate gland that is restricting urine flow through a urethra, positioning within an opening created by said surgical removal a tubular-in-configuration marker that is housed within a tubular-in-configuration sealant, said marker providing support for said sealant and said marker providing a slow delivery of therapeutic agents to the surgical site as said marker is bioabsorbed, said sealant expanding in response to contact by moisture present in said opening, said expansion of said sealant anchoring it to said urethra and to said prostate gland whereby the lumen of said marker performs the function of a urethra until the tissue heals.
44. A method for delivering pharmaceutical agents to a bladder, comprising the steps of entubing a first tubular section of sealant material within a tubular section of bioabsorbable marker material which is entubed within a second tubular section of sealant material, positioning the structure in dehydrated condition at the neck of the bladder where it joins a urethra, said sealant material expanding in response to contact by moisture to secure the marker in position, whereby drugs for treatment of bladder disease are released from said sealant and administered to the bladder as said sealant is bioabsorbed and whereby said sealant, when hydrated, has enhanced visibility under ultrasound relative to its visibility prior to hydration.
45. The method of
46. A method for sealing a biliary tract, comprising the steps of sealing said tract with a tubular marker housed within a tubular sealant in a tube-in-tube structure so that an open lumen of the tubular marker enables fluid to flow through the structure and so that the tubular sealant expands in response to contact with moisture to hold the tube-in-tube structure in position, said tubular marker containing a preselected substance for gradual release as the tube-in-tube structure biodegrades.
47. The method of
48. The method of
49. A method for sealing a fallopian tube, comprising the steps of sealing said fallopian tube with a tubular marker housed within a tubular sealant in a tube-in-tube structure so that an open lumen of the tubular marker enables fluid to flow through the structure and so that the tubular sealant expands in response to contact with moisture to hold the tube-in-tube structure in position, said tubular marker containing a preselected substance for gradual release as the tube-in-tube structure biodegrades.
Description [0083] How to achieve non-covalent bonding of ionic and non-ionic contrast agent with polymers such as PGA/PLA/PCL/PDO will now be described. Different techniques are employed to accomplish similar results in connection with covalent bonding. [0084] The starting materials employed in this invention for synthesizing the novel tissue marker include poly(DL-lactide), inherent viscosity (IV) of 0.63 dL/g (where the solvent is CHCl3 and the concentration is approximately 0.5 g/dL at 30� C.), 50/50 poly(DL-lactide-co-glycolide, IV of 0.17 dL/g (hexafluoroisopropanol, concentration �0.5 g/dL at 30� C.) and 75/25 poly(DL-lactide-co-glycolides), having IVs of 0.44 dL/g (CHCl3, concentration �0.5 g/dL at 30� C.) and 0.69 dL/g (CHCl3, concentration �0.5 g/dL 30� C.). These materials are commercially available from Birmingham Polymers, Inc., of Birmingham, Ala. [0085] Further starting materials for synthesis of the novel tissue marker include poly (DL-lactide), IV of 1.6 dL/g (CHCl3, concentration 0.1% at 25� C.), commercially available from Boehringer Ingelheim of Petersburg, Va., under the trademark RESOMER� R 207. Contrast agents sodium diatrizoate and 5-(N-2,3-dihydroxypropylacetamido)-2,4,6-triiodo- N,N′-bis(2,3-dihydroxypropyl) isophthalamide (iohexol) is commericially available from Sigma Chemical Co. of Milwaukee, Wis. Glycolide and DL-lactide monomers are commercially available from Purac America Inc. of Lincolnshire, Ill. 1-Dodecanol and ε-caprolactone are commercially available from Aldrich Inc. of Milwaukee, Wis. Tin (II) 2-ethylhexanoate is commercially available from Air Products and Chemicals, Inc. of Allentown, Pa. DL-lactic acid (JT Baker reagent) is commercially available from VWR Scientific of Bridegeport, N.J. Solvents such as tetrahydrofuran (THF), toluene, methanol, and hexanes of reagent grade or better are commercially available from multiple well-known sources. [0086] As a first example, synthesis of 75/25 poly(DL-lactide-co-ε-caprolactone) copolymer, hereinafter referred to as 75/25 DL-PLCI, is performed by charging 22.5 grams of ε-caprolactone, 310 mls of toluene, 0.422 grams in 3.02 mls of tolulene solution of 1-dodecanol and 0.382 grams in 2.34 mls of tolulene solution of stannous octoate catalyst into a one liter, three neck, round bottom flask. The reaction solution is placed in an argon atmosphere, stirred with an overhead stirrer that includes a glass stirrer shaft equipped with a Teflon� blade and approximately 100 mls of the solvent is distilled off at atmospheric pressure. The reaction temperature is lowered to approximately 90� C. and 67.5 grams of solid DL-lactide is added to the solution in one portion. The reaction temperature is raised to approximately 110� C. to afford a gentle reflux. After forty eight hours at that temperature, heating is discontinued and the reaction solution temperature is allowed to fall to 75�. The solution is diluted with 600 mls of toluene and stirred at 55-60 for 1.5 hours. The diluted reaction solution is transferred into a crystallizing dish and the polymer is precipitated with one liter of hexanes. The supernatant is then decanted off and the viscous residue dried for one to three days under a vacuum at 40� C. to a constant weight. The solid polymer is removed from the dish and stored under an argon atmosphere at 30� C. [0087] Synthesis of 20/80 poly(DL-lactite-co-ε-caprolactone), hereinafter referred to as 20/80 DL-PLCI and 10/90 poly(glycolide-co-ε-caprolactone), hereinafter referred to as 10/90 PGCI copolymers are prepared by the same process used for the preparation of 75/25 DL-PLCI in the first example, with the exception that, in the case of the 20/80 DL-PLCI copolymer, DL-lactic acid is used as the initiator instead of 1 -dodecanol. The contents of each monomer in the final purified polymers are determined by high resolution proton nuclear magnetic resonance spectroscopy and these are summarized in Table 1. That table further includes the melting points for 20/80 DL-PLCI and 10/90 PGCI copolymers, which are obtained by differential scanning calorimetry (DSC). [0088] Molecular weights were determined by GPC using methylene chloride solvent and polystyrene standards. [0089] In a third example, the 75/25 poly(DL-lactide-co-glycolide) with iohexol is formulated by preparing a 2% by weight over volume solution of the iohexol contrast agent by mixing 5.15 grams of the solid contrast agent in 130 mis of methanol in a 500 ml Erlenmeyer flask for 5-10 minutes until the solid is fully dissolved. The solution is then diluted with 130 mls of tetrahydrofuran (THF) to provide the 2% solution. A 6% solution of the biodegradable polymer is prepared in a one liter Erlenmeyer flask by addition of 330 mls of THF to 20.6 grams of the solid 75/25 DL-PLG polymer. The mixture is stirred with gentle heating (30-40� C.) until the solid is dissolved. The entire contrast solution is then slowly poured into the stirred polymer solution to give a single-phase solution of the polymer and the contrast agent. The combined solution is stirred for an additional five minutes and then the polymer and contrast agent are co-precipitated with hexanes. The precipitation is achieved by rapid addition of two volumes of hexanes to a rapidly mixed solution of the polymer/contrast solution. The mixture is again stirred for an additional five minutes and then allowed to sit unstirred at room temperature for five to ten minutes to allow the solid to settle to the bottom of the flask. The supernatant is then decanted and discarded and the semi-solid residue is dried under vacuum for one to two days at 40� C. to a constant weight. Quantitative recovery of 100.8% of the solids is obtained for the polymer and the contrast agent in this example. The solid, which is used for fabrication of the novel markers, contains 20% by weight of contrast agent as a homogenous mixture with the biodegradable polymer. [0090] To study the effect of the contrast agent content in the biodegradable markers on their visualization under X-ray imaging, two different DL-PLG polymers are formulated with the iohexol contrast agent in which the contrast is varied between 5 and 40% by weight. These markers are formulated by a procedure similar to the procedure for the marker prepared in the third example. The composition of these biodegradable marker solids is summarized in Table 2. The recovery of the solids after the hexanes precipitation step is greater than 97% for all of the marker compositions listed in Table 2. [0091] The contrast solution may also be an ionic contrast solution such as sodium diatrizoate, for example. [0092] The novel biomarkers may be fabricated by extrusion, injection molding, or compression molding. Multiple sizes and shapes may be fabricated using these or similar manufacturing processes. By controlling pressure, temperature, and extrusion speed rate during the extrusion process, differing sizes and properties are obtainable. During the development of this invention, different extrusion and compression molding processes were used to fabricate the markers. [0093] The novel biomarkers and the novel sealant material may be combined in a variety of fabrication processes. During the development of this invention, insert molding was used to combine the marker and the sealant to one another. Different sizes and shapes having differing properties may be manufactured using insert injection and compression molding, for example. [0094] To extend the biodegradable marker's range of properties such as degradation times, ability to be visualized under ultrasound, hardness and fabrication temperatures, marker solids are prepared from additional types of polymers with both ionic and non-ionic contrast agents as indicated in Table 3. Most of these biodegradable markers are formulated with 20% contrast agent. The recovery of the solids after the hexanes precipitation step is greater than 91% in all of these formulations. [0095] The type of polymer used can be any of the biodegradable polymers such as other PLGA polymers, e.g. , 50/50 DL-PLGA, 50/50 L-PLGA, etc., or the L-PLCI, PGCI, etc. [0096] The contrast agent can be formulated in these polymers at any concentration ranging from 0 to 50% by weight, but preferably at 70% by weight. (That statement contradicts itself). [0097] The solvent combinations can also be varied as well as the precipitation methods. [0098] There are many applications for the novel implants. For example, during diagnosis of hepatic carcinoma or other hepatic disease using a liver biopsy under CT visualization, a biopsy tract is formed. The tract may be plugged to prevent bleeding by using the above-mentioned PGA/PLA/PCL/PDO based polymer combined with a contrast agent for visibility and encapsulated within a hydrogel. Drugs or any other pharmaceutical agents could be delivered to the liver by replacing the contrast agent with such drugs or agents. [0099] As another example, a heart biopsy may be conducted near diseased heart tissue using a mechanical biopsy gun. The biopsy tract or tracts are then filled with different growth factors and stem cells to promote angiogenesis in the heart muscle tissue. One method for sealing the tract so that the stem cells and growth factor are constrained to stay in the biopsy tract for a prolonged period of time is disclosed in the second-incorporated disclosure. The present disclosure teaches the integration of two polymers where a PGA/PLA/PCL/PDO with a drug agent is encapsulated within a dehydrated hydrogel. The dehydrated hydrogel becomes hydrated within a few minutes and its expansion provides an anchoring means. [0100] This invention also has utility in connection with prostate cancer biopsies where a biopsy needle is inserted though the rectum into the prostate gland under ultrasound visualization. Introduction into the biopsy tract of a sealing means by means of a coaxial needle will prevent leakage through the bowel into the prostate. Moreover, the plug may be used to deliver drugs or other therapeutic agents. [0101] Similarly, the novel plugs have utility in connection with the sealing of cavities formed in a prostate gland by tissue reduction procedures undertaken after a diagnosis of BHP. Different drug agents are released over time to reduce inflammation or any other side effects. [0102] In another application, a tubular urethral stent has a thin wall formed of a PGA/PLA/PCL/PDC/PDO polymer substrate with or without pharmaceutical agents. A layer of dehydrated hydrogel covers the thin wall but does not block the lumen of the tube. The stent is introduced into the urethra and the hydrogel expands radially outwardly, anchoring to the urethral wall. This procedure is similar to the conventional placement of a urethral stent, but it is more advantageous because it is not permanent like metallic stents and does not require in situ curing like other biodegradable stents. [0103] The marker material that forms the inner tube also provides a drug-delivery means for the benefit of the patient. [0104] Growth factors or pharmaceutical agents encapsulated within the novel polymers may be used advantageously in the treatment of malignant brain tumors. The combination marker and sealant of this invention has utility in the context of gene therapy treatment as the carrier for the bio-active agents and as the anchoring means to position and secure the marker to the target area. [0105] The polymers disclosed herein are formulated to exhibit differing properties depending upon the application. Some are designed to degrade more slowly than others, some are more hydrophilic or more hydrophobic, and so on. In most applications, the contrast agent-containing polymers are formulated so that the marker is visible under X-ray and/or other imaging means for one month to six months or even longer. [0106] Turning now to the drawings, FIG. 1A depicts a tissue marker made in accordance with the teachings of the first-incorporated disclosure. It is provided in the form of a solid rod 10. Its interior is filled with a contrast agent or other pharmaceutical agent. FIG. 1B depicts marker 10 in solid rod form. [0107]FIG. 1C depicts a hydrogel-based sealant 12 made in accordance with the teachings of the second-incorporated disclosure. In this embodiment, it is of hollow cylindrical or tubular construction and is made of hydrogels. FIG. 1D depicts sealant 12 in solid rod form. [0108]FIGS. 1E and 1F depict the basic conception behind the present disclosure which teaches the combination of marker 10 and sealant 12 of the incorporated disclosures. The combination marker and sealant member 14 of FIG. 1E has an interior 10 formed of the FIG. 1B solid rod marker and an exterior housing 12 formed of the FIG. 1C sealant. In FIG. 1E, marker 10 is co-extensive with sealant 12. In FIG. 1F, interior marker 10 is again formed in the solid rod structure of FIG. 1B, but said solid rod 10 has an extent less than that of sealant 12 so that it is encapsulated therein as depicted. [0109] The novel combination marker and sealant member 14 is delivered to a site that requires sealing; the sealant is in dehydrated condition when delivered to the site. The sealant expands when activated by contact with water or moisture. The expansion of the hydrogel-based sealant 12 holds it in place. The contrast agent in marker 10 facilitates viewing of the site under various imaging techniques for a prolonged period of time. Marker 10 may also include therapeutic agents that are released over time as marker 10 is bioabsorbed. Hydrogels 12 are also bioabsorbed over time, but the time for such absorption is selected to exceed that of the absorption time of marker 16 if required by an application. [0110]FIG. 2A depicts a marker 10 having bulbous anchoring means at its opposite ends that extend beyond the opposite ends of hydrogel housing 12. FIG. 2B depicts marker 10 having said bulbous anchoring means when fully encased within hydrogel housing 12. [0111]FIG. 3A is a side elevational view depicting a tube-in-tube arrangement where marker 10 is provided in tubular form and is ensleeved within sealant 12 which is also provided in tubular form. FIG. 3B provides an end view thereof. [0112] Sealant 12 has a pair of open lumens in the embodiment of FIGS. 4A-C, and each of said open lumens has a marker 10 positioned therewithin. The sealant material of which outer housing 12 is formed is depicted in dehydrated form in FIG. 4A. In FIGS. 4B and 4C, the sealant has expanded due to hydration. In the embodiment of FIG. 4B, the lumen is small and in the embodiment of FIG. 4C the lumen is large. [0113] In addition to the cylindrical and rod-shaped markers 10 of FIGS. 1A and 1B, marker 10 could also be provided in the form of a rod having a pointed leading end as depicted in FIG. 5. The pointed leading end could serve as an anchoring means that prevents migration of marker 10 from its intended location. [0114] The harpoon shape of the leading end of the marker depicted in FIG. 6 would also provide an anchoring means. [0115] The embodiment of FIG. 7 provides a U-shaped tissue marker 10. This clip shape also has utility as an anchoring means. When the tissue marker is shaped such that it is self-anchoring, the hydrogel sealant is not required unless there is a need to seal a surgical or trauma-created opening. [0116] A latch means is added to the embodiment of FIG. 7 to produce the embodiment of FIG. 8. The latch means is provided to enhance the anchoring of marker 10. [0117] Hydrogel sealant 12 may also be provided in the form of a rod, tube, pointed rod, harpoon, clip, latched clip, and the like. [0118] Moreover, as depicted in FIG. 9, tissue marker particles, collectively denoted 10 a, may be dispersed within sealant 12. Such dispersal of tissue marker particles 10 a within hydrogel sealant 12 may be applied to any form of hydrogel 12. For example, marker particles 10 a could be dispersed throughout a harpoon-shaped sealant 12, a �U�-shaped sealant 12, and so on. [0119] The number of shapes is inexhaustible and these Figures are not intended to illustrate all possible shapes within the scope of this invention but are intended as exemplary only. The novel combined marker and sealant can be manufactured in any geometrical shape and size and the invention is not limited to the finite number of examples provided herein. [0120] Six (6) examples of applications for the novel marker/sealant combination will now be disclosed. [0121]FIG. 10 depicts a hepatic (liver) biopsy. Bore 20 is formed in liver 22 by the biopsy procedure. Plug 24 seals the bore at its surface to prevent bleeding at the biopsy site. Plug 24 may be formed of expandable sealant material 12 only so that it expands to securely seal the opening when contacted by bodily moisture, or it may include a marker 10 or marker particles 10 a housed within expandable hydrogel sealant material 12. These markers have utility for viewing or drug delivery or both. [0122] A diagrammatic longitudinal sectional view of an expanded artery after an angioplasty procedure is denoted 24 in FIG. 11A. Hydrogel sealant 12, in tubular form, is initially positioned within lumen 25 of the artery in unhydrated form; it then expands to the position depicted in FIG. 11B to hold the artery open. Marker material 10, also in tubular form, is positioned radially inwardly of sealant 12 and provides support therefor. [0123] In the alternative, expandable sealant material 12 may be provided in annular, i.e., ring form as depicted in FIG. 11C and a plurality of said rings may be disposed in longitudinally and equidistantly spaced relation to one another along the extent of the expanded section of artery, in transverse relation to the longitudinal axis of the artery, as indicated in FIG. 11D. Moreover, as depicted in FIG. 11E, marker material 10 in annular form may be sandwiched between inner and outer layers of sealant material 12. Where the bioabsorbable marker material contains a contrast agent, the location of the site is made apparent under imaging for a prolonged period of time. Where therapeutic agents are contained within the marker material, a time-release of said agents is provided as the marker material is slowly bioabsorbed. [0124] Still another application for the novel combination of materials is depicted in FIGS. 12A-F. FIG. 12A diagrammatically depicts a prostate gland 30 and a urethra 32 in perspective and FIG. 12B provide s a diagrammatic cross-sectional view thereof. If gland 32 is enlarged, a condition known as BHP, it can compress the urethra and cause a restricted urine flow. As indicated in FIG. 12C, the condition is surgically treated by removing the part of gland 30 that is applying pressure to urethra 32; the resulting opening is denoted 34 in FIGS. 12C and 12D. FIG. 12E indicates how a tubular-in-configuration marker 10 is housed within a tubular-in-configuration sealant 12 to provide support for said sealant and to provide a slow delivery of therapeutic agents to the surgical site. The moisture-activated expansion of sealant 12 anchors it to urethra 32 and to prostate gland 30. The urethra is usually damaged during TURP. The lumen serves as a temporary urethra until the prostate grows back. [0125]FIG. 13 depicts an application where drugs or other pharmaceutical agents are delivered to a bladder 40. This is a tube-in-tube-in-tube arrangement where a first tubular section of sealant material 12 is entubed within a tubular section of marker material 10 which is entubed within a second section of sealant material 12. The structure in dehydrated condition is positioned at the neck of bladder 40 where it joins urethra 32. Upon activation, sealant material 12 expands to secure the marker 10 in position. As sealant 12 is bioabsorbed, drugs for treatment of bladder disease are released from said sealant 12 and administered to the bladder. Pharmaceutical agents of smaller molecular size could be carried by bioabsorbable marker 10. [0126] The novel sealant, when hydrated, makes the site more visible under ultrasound. [0127]FIG. 14 depicts a biliary tract 50 where an opening therein is sealed by the structure depicted in FIGS. 3A and 3B, i.e. , tubular marker 10 is housed within tubular sealant 12 in a tube-in-tube arrangement. The open lumen of marker 10 enables fluid to flow through the structure. As in the other embodiments, sealant 12 expands in response to contact with moisture to hold the tube-in-tube structure in position and marker 10 contains either contrast agent or therapeutic agents, or both, for gradual release as the tube-in-tube structure biodegrades. [0128] The same tube-in-tube structure may be used to seal openings in fallopian tubes 60 a, 60 b, as diagrammatically depicted in FIG. 15. [0129] The invention is not limited to liver, artery, prostate gland, bladder, biliary tract and fallopian tube applications. In view of these exemplary applications, other applications will become apparent to those of ordinary skill in the medical arts. Expandable sealant material 12 has utility in sealing any opening and in providing an anchoring means for the marker material even if no sealing is required. The marker material may contain a contrast agent or a therapeutical agent, or both, that are released over time as the marker is bioabsorbed. [0130] It will thus be seen that the objects set forth above, and those made apparent from he foregoing description, are efficiently attained. Since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. [0131] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween. [0132] Now that the invention has been described, [0050] For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which: [0051]FIG. 1A is a perspective view diagrammatically depicting the tissue marker material in the form of a solid rod. It may also be interpreted as depicting said tissue marker material in the form of a hollow cylinder; [0052]FIG. 1B is a side elevation view diagrammatically depicting the marker material in solid rod form or in hollow cylindrical form, depending upon the interpretation of the drawing; [0053]FIG. 1C is a perspective view diagrammatically depicting the sealant material in solid rod form; [0054]FIG. 1D is a side elevation view diagrammatically depicting the sealant material in solid rod form; [0055]FIG. 1E is a perspective view diagrammatically depicting the marker of FIG. 1A housed within the sealant of FIG. 1C, in a rod-in-rod arrangement; [0056]FIG. 1F is a side elevation view that diagrammatically depicts a marker of FIGS. 1A or 1B encapsulated within the sealant material of FIG. 1D; [0057]FIG. 2A is a side elevation view diagrammatically depicting the marker material formed into a dog bone shape and ensleeved within the sealant material of FIG. 1E; [0058]FIG. 2B is a side elevation view diagrammatically depicting the marker material of FIG. 2A encapsulated within the sealant material of FIG. 1F; [0059]FIG. 3A is a longitudinal sectional view depicting the marker of FIG. 1A ensleeved within the sealant material of FIG. 1C in a tube-in-tube arrangement; [0060]FIG. 3B is an end view of the parts depicted in FIG. 3A; [0061]FIG. 4A is a longitudinal sectional view depicting a pair of the markers of FIG. 1A ensleeved within a double-lumened sealant material in dehydrated form; [0062]FIG. 4B depicts the parts of FIG. 4A when the sealant material is hydrated; [0063]FIG. 4C is similar to FIG. 4B except it depicts the sealant material having lumens that are larger in diameter than the lumens of FIG. 4A and FIG. 4B; [0064]FIG. 5 is a side elevation view of a marker or sealant having a pointed distal end; [0065]FIG. 6 is a side elevation view of a marker or sealant having a harpoon-shaped distal end; [0066]FIG. 7 is a side elevation view of a marker or sealant having a �U�-shaped or clip-shaped configuration; [0067]FIG. 8 is a side elevation view of a marker or sealant like that of FIG. 7 but further equipped with a latch means; [0068]FIG. 9 is a side elevation view of a sealant having marker particles embedded therein; [0069]FIG. 10 diagrammatically depicts the combination marker and sealant when used to seal a liver biopsy tract; [0070]FIG. 11A is a longitudinal sectional view of an artery depicting how a section thereof is expanded by an angioplasty procedure; [0071]FIG. 11B is a view like FIG. 11A and adds a longitudinal sectional view of the combination marker and sealant of this invention positioned in said expanded section of said artery; [0072]FIG. 11C is a cross-sectional view of the sealant when hydrated and in annular form; [0073]FIG. 11D is a view like FIG. 11A and depicts a plurality of the ring-shaped sealants of FIG. 11C disposed in supporting relation to said expanded area of said artery, said sealants being used in conjunction with a metallic stent; [0074]FIG. 11E is an end view depicting a tube-in-tube-in-tube arrangement where the marker of FIG. 1A ensleeves a first sealant of tubular configuration and is ensleeved by a second sealant of tubular configuration having a diameter larger than the diameter of the first sealant; [0075]FIG. 12A is a diagrammatic view of a prostate gland and a urethra; [0076]FIG. 12B is a sectional view taken along line 12B-12B in FIG. 12A; [0077]FIG. 12C is a diagrammatic view of the prostate gland of FIG. 12A after a tissue reduction procedure has been performed; [0078]FIG. 12D is a sectional view taken along line 12D-12D in FIG. 12C; [0079]FIG. 12E is a diagrammatic view like that of FIG. 12C, depicting the combination marker and sealant positioned in structural support relation to the excised part of the gland; [0080]FIG. 13 is a diagrammatic view of the marker and sealant combination when positioned at the juncture of a bladder and a urethra; [0081]FIG. 14 is a diagrammatic view of the marker and sealant combination when used in a biliary tract; and [0082]FIG. 15 is a diagrammatic view of the marker and sealant combination when used in a fallopian tube. [0001] 1. Field of the Invention [0002] This invention relates, generally, to a biodegradable tissue marker and sealant. More particularly, it relates to a tissue marker formed of a biodegradable polymer having drug-delivery capabilities. It further relates to a sealant that encapsulates the tissue marker and which serves to help anchor the tissue marker against migration. [0003] 2. Description of the Prior Art [0004] U.S. Pat. No. 6,350,244 entitled Bioabsorable Markers For Use In Biopsy Procedures to the present inventor discloses a bioabsorbable marker that is positioned near a lesion or tumor during a biopsy procedure. The marker includes a contrast agent and is bioabsorbed slowly so that the biopsy site can be located weeks or even months later if needed. U.S. Pat. No. 6,350,244 is hereby incorporated by reference into this disclosure, and is hereinafter referred to as the first-incorporated patent. [0005] Co-pending U.S. patent application Ser. No. 09/683,282, filed Dec. 7, 2001, entitled Bioabsorbable Sealant, also to the present inventor, discloses a sealant that expands upon contact with water or other bodily fluid. It can also expand upon contact with heat or other stimulus. The sealant has utility in sealing various openings in the body such as a hole in a lung, an opening in the myocardial septum, and the like. It is also useful in sealing a blind bore that contains stem cells that promote angiogenesis. U.S. patent application Ser. No. 09/683,282 is also hereby incorporated by reference into this disclosure, and is hereinafter referred to as the second-incorporated disclosure. [0006] Prior to this disclosure, it was not known that the tissue marker of the first-incorporated disclosure and the sealant of the second incorporated disclosure could be combined and used in combination with one another. Anchoring the tissue marker against migration was problematic. Moreover, although the tissue marker included a contrast solution to facilitate its imaging under X-rays, it was unknown how to use the tissue marker or the sealant as a drug delivery means. [0007] Nor was it known that a tissue marker could be formed into a shape that would enable it to serve as its own anchoring means. [0008] Nor was it known how polymers having utility as tissue markers could be formulated to achieve differing degradation rates. More particularly, it was not known how to make different polymers to contain contrast for different amounts of time, such as one month to six months or more by using two different polymers. [0009] Nor was it known how to formulate a marker polymer with a therapeutic drug or other pharmaceutical agent so that the degradation of the marker would gradually release the drug or agent to a site. [0010] Nor was it known how the polymers could be formulated to exhibit differing expansion rates when exposed to water or other liquid fluids. [0011] The sealants of the prior art require in-situ curing. For example, Focal Sealant� is an in-situ sealant available from Genzyme Corporation. Prior art sealants such as Focal Sealant require the application of a stimulant such as visible light, heat, and the like thereto. [0012] Accordingly, what is needed is a combination tissue marker and sealant that can be formed into many different shapes and sizes, depending upon the application, that can degrade at different rates, depending upon the application, that can expand in response to moisture or other bodily fluids at different rates, depending upon the application, and that does not require in-situ curing. [0013] There is a need as well for a bioabsorbable tissue marker that can deliver drugs or other therapeutic agents to a site over a prolonged period of time. [0014] There is a further need for a sealant that can anchor a tissue marker against migration, that can provide a seal for openings in tissue, and that biodegrades over a period of one to six months or more. [0015] Moreover, there is a need for a combination tissue marker and sealant that requires no in-situ curing as aforesaid and which therefore requires no initiators, buffers or other chemicals, proteins, enzymes, visible light, UV, accelerator, nor addition of foreign chemicals into the body. [0016] A need also exists for a means for making tissue markers more compatible with surrounding tissue. Tissue markers are hard and have little compatibility with surrounding tissue. Thus there is a need for a cushioning means that surrounds a marker and which provides a more compatible interface means with surrounding tissue. [0017] Biodegradable polymers in general have been used in many medical devices and implant applications. For example, they have been used as orthopedic implants, tissue sealants, sutures, and as ligating clips. The medical devices incorporating these polymers are made, primarily, of biodegradable materials such as poly(dioxanone) (PDO), polyethylene glycol (hydrogels, polylactides (PLA), polyglycolides (PGA), polycaprolactone (PCL), and their copolymers. Some of the polymers, such as hydrogels, are hydrophilic. Others such as PCL are hydrophobic. Because these polymers degrade by hydrolysis, the type of polymer and its physical form used in a particular application has an effect in defining the degradation period. [0018] Traditional brain tumor treatment includes surgery, radiotherapy, and chemotherapy. Alternative strategies are needed due to the high rate of recurrence of tumors after such treatment and their resistance to radiation and cytostatics. In the recent past, gene therapy treatments such as reversion of the malignant phenotype by down regulation of the oncogene expression or insertion of normal tumor genes have been tried. One challenge with gene therapy treatments concerns the prevention of immunorejection of genetically modified cells after intracranial implantation. A further challenge is to achieve efficient gene transfer, as well as prolonged gene expression within the relevant cells. [0019] Numerous other surgical procedures would be facilitated by tissue markers that degrade over predetermined periods of time, that include contrast agents so that they can easily be found, that do not migrate, that interface well with surrounding tissue, and that deliver drugs or other therapeutic agents to a site over a predetermined length of time. [0020] In view of the prior art considered as a whole at the time the present invention made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled. [0021] Biodegradable polymers and co-polymers are combined with or without ionic and non-ionic contrast agents, depending upon the application. For example, no contrast agent is needed in an application where there is no need to view a site at a later date. [0022] The novel formulations that include contrast agents are designed to allow the radiopacity of the markers to last for an extended period of time so that they can be seen under X-ray or other imaging means for further diagnostic or intervention procedures at a date that may be weeks or months after implanting of the marker. [0023] The novel plug is treated so that it is visible under ultrasound, magnetic resonance imaging, and other imaging techniques if an application requires such visibility. Accordingly, it may contain or be impregnated with a contrast solution containing radium, iodine, beryllium, or other contrasting agent. [0024] The plug is impregnated with a contrasting agent to facilitate detection of the plug by imaging means selected from the group of imaging means consisting of magnetic resonance imaging, ultrasound, Doppler, and roentgenological means including x-ray, computed axial tomography (CAT) scanning, also known as CT scan, mammography, and fluoroscopy, or other known or hereafter known imaging techniques. [0025] The plug may also include a radioactive substance detectable by a radiation detecting means including a gamma counter and a scintillation counter. In another alternative, the plug includes a transmitting means adapted to transmit signals in the electromagnetic spectrum that are detectable by receivers adapted to receive signals in the electromagnetic spectrum. [0026] The novel polymers are based upon well-known polymers such as polyactides (PLA), including polylactic acid, for example, polyglycolides (PGA), including polyglycolic acid, for example, polycaprolactone (PCL), poly(dioxanone) (PDO), collagen, renatured collagen, gelatin, renatured gelatin, crosslinked gelatin, and their co-polymers. The blend of polymers and copolymers is designed to degrade as a result of hydrolysis of polymer chains into biologically acceptable and progressively smaller components such as polylactides, polyglycolides, and their copolymers. These break down eventually into lactic and glycolic acid, enter the Kreb's cycle and are broken down into carbon dioxide and water and excreted. [0027] Some of these polymers and copolymers do not possess the mechanical properties that are required for certain applications. For example, as implants for soft tissue PGA, PLA, PCL, PDO and their copolymers may require increased flexibility and a modulus of elasticity that is closer to soft tissue. Some hydrogels, due to their water content, provide a more flexible structure that is similar to soft tissue. Therefore, by combining the polymers that lack certain required mechanical properties such as a suitable modulus of rigidity or modulus of elasticity with hydrogels, suitable degradation and drug delivery properties are obtainable and an exterior is achieved that has mechanical properties similar to the mechanical properties of soft tissue. [0028] PLA, PGA, PCL, PDO and their copolymers are designed to provide a sustainable and gradual degradation and therefore slow release of drugs with the degradation of the polymer substrate. Hydrogels are not suitable for prolonged drug delivery without using additional bonding of the drug to the hydrogels especially with small size molecule pharmaceutical agents. [0029] Thus it is understood that a primary teaching of this invention relates to biodegradable polymers having utility as tissue markers as taught by the first-incorporated patent and as sealants as taught by the second-incorporated disclosure. When combined, the tissue marker and sealant serve as a drug-delivery means as the substrate of the polymer degrades. Advantageously, the expanded sealant prevents migration of the marker as well, and provides a soft interface means between the marker and surrounding soft tissue. [0030] More particularly, poly (DL-lactide) is used to provide a biodegradable substrate that allows slow degradation. However, it swells as water or other bodily fluid penetrates into the substrate. Different molecular weights could be used to achieve a different hydration rate. Delayed hydration provides a better visualization under ultrasound when further diagnosis or intervention is required. [0031] An alternative method for achieving a different degradation rate is to employ a biodegradable hydrophobic polymer coating to delay the penetration into the substrate by water or other bodily fluid. The hydrophobic coating may be sprayed onto the substrate or the substrate may be dipped into the coating. Either way, the thickness of the coating is controlled because a thicker coating resists penetration for a longer time than a thinner coating. Polycaprolactone (PCL) degrades nicely, for example, and therefore works well when sprayed or coated onto the substrate. Teflon� does not work because it forms a substantially permanent shield. [0032] When anchoring an implant in a specific area is required, a PGA/PLA/PCL/PDO based polymer combined with a contrast agent for visibility if required for a particular application is encapsulated within a hydrogel such as a PEG-based hydrogel. The encapsulation is accomplished by any suitable means such as mechanically combining the tissue marker and sealant in a mold, by compression, and the like. The hydrogel part of the combined polymer is dehydrated and delivered to the target site. Hydration of the polymer causes its expansion and thus provides a mechanical anchoring of the implant in the tissue. These properties are attained by combining the teachings of the first and second-incorporated disclosures. Where the polymer is used as a tissue marker, it is molded or extruded into different shapes to provide anchoring properties. [0033] The contrast agent, if provided, is also accompanied by or replaced with different pharmaceutical agents such as anti-cancer drugs, antibiotics, anti-inflammatory drugs and the like that are slowly released using PGA/PLA/PCL/PDO substrates of the first-incorporated disclosure while the hydrogels of the second-incorporated disclosure provides a suitable anchoring means. The degradation of the external hydrogel may also be tailored to have a prolonged degradation time while the PGA/PLA/PCL/PDO combined with a drug agent could be degraded at a faster rate. [0034] Examples of suitable bioabsorbable materials that expand when contacted by water include hydrogels, collagen, polysalactic acid, and any other suitable hydrophilic agents. [0035] Examples of polymers that swell in the presence of aqueous fluids such as biological fluids will now be disclosed. Virtually all of the following polymers are hydrogels. Synthetic hydrogels can be prepared from the following classes of polymers and these are generally considered to be non-biodegradable:poly (hydroxyalkyl methylacrylates) such as poly(glyceryl methacrylate)poly(acrylamide) and poly(methacrylamide) and derivativespoly(N-vinyl-2-pyrrolidone)anionic and cationic hydrogelspoly(vinyl alcohol)poly(ethylene glycol) diacrylate and derivatives from block copolymers composed of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) and poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) blocks, respectively; All of the above can be cross-linked with agents such as ethylene glycol dimethacrylate or methylene-bis-acrylamide. [0036] Biodegradable synthetic hydrogels can be prepared from polymers such as those listed above by incorporating one or more of the following monomers:Glycolide, Lactide, e-Caprolactone, p-Dioxanone and Trimethylene Carbonateln addition, biodegradable hydrogels can be based on natural products such as the following:Polypeptides such gelatin which may be cross-linked with formaldehyde or glutaraldehyde and various other dialdehydes. [0037] Modified chitin hydrogels, which may be prepared from partially N-deacetylated chitin which, may then be cross-linked with agents such as glutaraldehyde. [0038] Dextran, a polysaccharide, can be derivatized with groups such as 3-acryloyl-2-hydroxypropyl esters and subsequently cross-linked by free radical copolymerization with N′,N′-methylenebisacrylamide. [0039] Starch may be similarly derivatized or using glycidyl acrylate followed by free radical cross-linking as described above. [0040] The plug is impregnated with a contrasting agent to facilitate detection of the plug by imaging means selected from the group of imaging means consisting of magnetic resonance imaging, ultrasound, Doppler, and roentgenological means including x-ray, CT scan, mammography, and fluoroscopy. [0041] Suitable contrast agents include a colored substance such as a dye or colorant such as methylene blue, gentian violet, indigo, dyes used in tattooing or colorant particles such as India, indigo, carbon particles or carbon preparations described in Langlois, S. L. P. and Carter, M. L. Carbon Localization of Impalpable Mammographic Abnormalities, Australis Radiol. 35:237-241 (1991) and/or Svane, G. A. Stereotaxis Technique for Preoperative Marking of Non-Palpable Breast Lesions, Acta Radiol. 24 (2): 145-151 (1983). Chemical compounds that serve as suitable contrast agents include AgCl, Agl, BaCO3, BaSO4, K, CaCO3, ZnO, Al2O3, AGNO3, ammonium salts, sodium salts, potassium salts, ethiodized oil, isohexol, isopamidol, gas, lipid, oil, and all possible combinations thereof. Alternatively, the plug includes a radioactive substance detectable by a radiation detecting means including a gamma counter and a scintillation counter. In another alternative, the plug includes a transmitting means adapted to transmit signals in the electromagnetic spectrum that are detectable by receivers adapted to receive signals in the electromagnetic spectrum. [0042] This invention further includes the fabrication of tubular implants for implanting in tubular organs. Such a structure includes a lumen defined by a PGA/PLA/PCL/PDO polymer and a hydrogel that provides the exterior of the implant. Thus, as the hydrogel expands upon contact with a liquid fluid, it anchors itself into the surrounding tissue. The inner layer of the hydrogel contains a circular solid polymer made of PGA/PLA/PCL/PDO as a structural support to maintain an open lumen. The lumen remains open even when the hydrogel has fully expanded because the expansion is radially outward, away from the PGA/PLA/PCL/PDO polymer substrate that defines the lumen. A drug or drugs may be added to the polymer substrate so that said drug or drugs are delivered over time to the patient as the substrate degrades. As mentioned above, in most cases the polymer substrate is designed to degrade at a rate faster than the degradation rate of the hydrogel cover. [0043] The primary object of this invention is to provide a combination tissue marker and sealant that prevents migration of the marker. [0044] Another important object is to provide biodegradable polymers that perform the functions of marking a site, delivering drugs or other therapeutic agents to a site, and sealing openings or tracts left by a biopsy procedure or other surgical procedure. [0045] Another object is to provide a hydrophobic coating that extends the degradation rate by shielding the substrate from moisture or bodily fluids for a predetermined time. [0046] Another important object is to provide a combination tissue marker and sealant that does not require in-situ curing. [0047] Yet another important object is to encapsulate a tissue marker in a sealant material that is more compatible to soft tissue than is a tissue marker. [0048] These and other important objects, advantages, and features of the invention will become clear as this description proceeds. [0049] The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims. Referenced by
Legal Events
Rotate |


text:
recipe reviews for:
"Make this snack idea for your Memorial Day or Independence Day celebration for a great red, white, and blue addition to the buffet table."
Cooking Level: Intermediate
My Profile | Cooks I Like Reviews | Photos | Recipes | Menus | Blog
Cooking Level: Expert
Everything you need to party like a leprechaun.
New for spring! Good-for-you food you'll love to eat.
Delicious recipes, party ideas, and helpful cooking tips! Get a year of Allrecipes magazine for just $9.99!
Find out how to make creamy, delicious homemade spinach dip.
See how to make this crowd-pleasing seven-layer dip.
Learn how to make this simple, creamy artichoke dip.


text:
Looking for something else?
Residence Ville Lago LuganoVia Casamora 6, 21050 Porto Ceresio (Show map)
Score from 5 reviews
The Art Nouveau Residence Ville Lago is located on the shores of Lake Lugano, 9 miles from Varese. It offers apartments with lake views, in villas surrounded by alpine gardens. Apartments at the Residence Ville Lago Lugano are elegantly furnished and feature Carrara marble floors. Each comes with a balcony or patio, free Wi-Fi and an LCD TV with satellite channels. A breakfast menu is available at the property. Guests can also enjoy relaxing around the free-form pool or on the private beach. Lugano, across the Swiss border, is just 12 miles from the Residence Ville. Como is a 50-minute drive away, along the scenic E35 highway through Switzerland and Lombardy. Apartments/rooms: 19 Why use Booking.com?Why use Booking.com?Low ratesNo booking fees • Save money! • Best Price Guaranteed 434,134 properties worldwide
Including 116,903 vacation rentals Unbiased reviews26,220,000 reviews from real guests We speak your languageWebsite and customer service in English (US) and 41 other languages Booking is safeWhen you book with us your details are protected by a secure connection. OutdoorsOutdoor Pool, Grounds, Terrace ActivitiesPrivate Beach Area InternetFree! Wi-Fi is available in all areas and is free of charge. ParkingFree! Free private parking is available on site (reservation is not needed). GeneralSafe, Facilities for Disabled Guests, Family Rooms, Heating Check-in3:00 PM - 7:00 PM Check-out8:00 AM - 10:30 AM Cancellation/
Atahotel VareseWith a fresh design combining style and comfort, Atahotel Varese Business & Resort offers great modern amenities and stunning views of the mountain, the hills and the horse racing tracks.Most recent booking for this hotel was today at 10:25
Score from 233 reviews
Very good
- 8.4/10
Hotel Il CannetoThis friendly, family-run hotel welcomes you to the picturesque town of Porto Ceresio, 160 yards from Lake Lugano. Start your day with breakfast out in the peaceful garden.Most recent booking for this hotel was today at 13:17
Score from 85 reviews
- 7.6/10
Park Hotel RovioThe Park Hotel Rovio on the south side of the Monte Generoso Rovio, is just over 1 mile from Lake Lugano and 9 miles from Lugano. It features an outdoor pool and free parking.Most recent booking for this hotel was today at 14:46
Score from 440 reviews
Very good
- 8/10
Strandhotel ZappaWith an immediate lakefront location on Lago Lugano, Strandhotel Zappa offers neatly furnished rooms and suites with free Wi-Fi in Brusino Arsizio. It features a private beach and on-site water...Most recent booking for this hotel was today at 13:09
Score from 55 reviews
Very good
- 8.3/10


text:
Payne County Youth Services really needing a volunteer to take on the upkeep of the PCYS website. There isn't much time involved in this task on a day-to-day basis. Right now, there may be a little more time getting it up to date, including adding the latest newsletter and updating some personnel.
If anyone interested in working with PCYS, please contact our office at 405-744-5145 and we will provide you with more information. Also, share this information with your friends that you may know is interested.
Payne County Youth Services really needi
Filed under Volunteer Opportunities


text:
Whipsnade Zoo, Bedfordshire.
Various shots of a lovely baby giraffe called Boxer (born on Boxing Day) walking about an enclosure with its mother. The father is jealous and is kept in a separate enclosure. Boxer gambols about in a frisky manner - very cute!
We always welcome comments and more information about our films.
All posts are reactively checked. Libellous and abusive comments are forbidden.


text:
Open AccessThis article is
- freely available
- re-usable
Sensors 2010, 10(3), 2348-2358; doi:10.3390/s100302348
Refractive Index Sensor Based on a 1D Photonic Crystal in a Microfluidic Channel
Department of Micro and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345 East, DK-2800 Kongens Lyngby, Denmark
Department of Photonics Engineering, Technical University of Denmark, DTU Fotonik, Building 345 West, DK-2800 Kongens Lyngby, Denmark
* Author to whom correspondence should be addressed.
Received: 27 January 2010; in revised form: 10 February 2010 / Accepted: 5 March 2010 / Published: 22 March 2010
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)
Download PDF Full-Text [1313 KB, uploaded 25 March 2010 14:15 CET]
Abstract: A refractive index sensor has been fabricated in silicon oxynitride by standard UV lithography and dry etching processes. The refractive index sensor consists of a 1D photonic crystal (PhC) embedded in a microfluidic channel addressed by fiber-terminated planar waveguides. Experimental demonstrations performed with several ethanol solutions ranging from a purity of 96.00% (n = 1.36356) to 95.04% (n = 1.36377) yielded a sensitivity (Δλ/Δn) of 836 nm/RIU and a limit of detection (LOD) of 6 x 10-5 RIU, which is, however, still one order of magnitude higher than the theoretical lower limit of the limit of detection 1.3 x 10–6 RIU.
Keywords: 1D photonic crystal; refractive index sensor; integrated waveguides; electrochromatography
Article Statistics
Click here to load and display the download statistics.Cite This Article
MDPI and ACS Style
Nunes, P.S.; Mortensen, N.A.; Kutter, J.P.; Mogensen, K.B. Refractive Index Sensor Based on a 1D Photonic Crystal in a Microfluidic Channel. Sensors 2010, 10, 2348-2358.
AMA StyleNunes PS, Mortensen NA, Kutter JP, Mogensen KB. Refractive Index Sensor Based on a 1D Photonic Crystal in a Microfluidic Channel. Sensors. 2010; 10(3):2348-2358.
Chicago/Turabian StyleNunes, Pedro S.; Mortensen, Niels Asger; Kutter, Jörg P.; Mogensen, Klaus B. 2010. "Refractive Index Sensor Based on a 1D Photonic Crystal in a Microfluidic Channel." Sensors 10, no. 3: 2348-2358.


text:
Artist: Queen
Album: Sheer Heart Attack
Genre: Rock
Sheer Heart Attack
Bet Your Bottom Dollar Bill You're A Playboy
Daddy Cool with a ninety dollar smile
Took my money out of gratitude
And he git right outa town - well
I gotta getty up, steady up, shoot him down
Gotta hit that latitude - babe
Big bad Leroy Brown he got no common
sense - no, no
He got no brains but he sure gotta lot of style
Can't stand no more in this here jail
I gotta rid myself of this sentence
Gotta get out the heat, step into the shade
Gotta get me there dead or alive - babe
Wooh, wooh, big bad Leroy, wooh, wooh,
Wooh, wooh, big bad Leroy - Brown - well
Big Mama Lulu Belle she had a nervous breakdown
(She had a nervous breakdown)
Leroy's taken her honey chile away
But she met him down at the station
Put a shot gun to his head
And unless I be mistaken
This is what she said
"Big bad, big boy, big bad Leroy Brown
I'm gonna get that cutie pie"
Get the embed code
Note: When you embed the widget in your site, it will match your site's styles (CSS). This is just a preview!
Preview the embedded widget
Queen Lyrics provided by SongLyrics.com
1 | Procession |
2 | Seven Seas of Rhye (Instrumental) |
3 | Yeah |
4 | Friends Will Be Friends Will Be Friends... |
5 | A Kind of 'A Kind of Magic' |
6 | Garbage |
1 | HomeEdward Sharpe & The Magnetic Zeros |
2 | Sweet DispositionTemper Trap |
3 | IslandsThe xx |
4 | Rolling In The DeepAdele |
5 | CrystalisedThe xx |
6 | You Found MeThe Fray |
7 | Let It Be (various Artists)Bonnie Tyler |
8 | Heart Skipped A BeatThe xx |
9 | Someone Like YouAdele |
10 | Many Of HorrorBiffy Clyro |
View All |
Genres |
Top Lyrics |
SongLyrics |


text:
Published November 02, 2012, 11:30 PM
Lind: Heart association official says North Dakota has 'great system of stroke care'
Neighbors' mailbag is overflowing. So let's dig into it. June Herman, of Ypsilanti, N.D., regional vice president of advocacy for the American Heart Association, says she "loved reading the story on Marilynn Moe," referring to a column about a woman who survived a stroke.By: Bob Lind, INFORUM