A method for reducing asthmatic response in a mammal comprising administering a response-reducing amount of O-desulfated heparin to the mammal, thereby reducing the asthmatic response. The amount can be administered by aerosolization. The O-desulfated heparin has O-desulfation at least at the 2-O and 3-O positions.

Asthma is an inflammatory disease of lung airways that makes the airways prone to narrow too much and too easily in response to a wide variety of provoking stimuli. In the lung, the major innervating sensory and motor nervous system is contained within the vagus nerve (FIG. 1). Exposure of the airway to irritants such as sulfur dioxide, prostaglandins, histamine and cold air can stimulate afferent sensory fibers of the vagus nerve, thereby setting off bronchoconstriction, or airway narrowing, due to reflex release of acetylcholine by cholinergic efferent motor branches of the vagus nerve. While this reflex is present in normal individuals, it is greatly exaggerated in asthmatic patients. This exaggerated narrowing is often called airways hyperreactivity.
Airways hyperreactivity in asthmatic patients and in animal models of asthma is thought to arise from increased release of the endogenous neurotransmitter acetylcholine from the efferent motor vagus nerve endings innervating the airway (A. D. Fryer, et al., Journal of Clinical Investigation (1992) 90:2292-2298). In the airway, release of acetylcholine from the vagus nerves is under the local control of inhibitory muscarinic autoreceptors on the postganglionic nerves (FIG. 1). These autoreceptors are called M.sub.2 muscarinic receptors, while the muscarinic receptors on airway smooth muscle are M.sub.3 receptors. Thus, acetylcholine released from the vagus nerve stimulates both M.sub.3 muscarinic receptors on airway smooth muscle, causing bronchoconstriction, and M.sub.2 muscarinic receptors on the nerves, decreasing further release of acetylcholine. In asthmatics, inhibitory M.sub.2 muscarinic receptors are dysfunctional, resulting in exaggerated acetylcholine release and, therefore, exaggerated bronchoconstriction, or airways hyperreactivity, in response to a given irritant airway stimulus (A. D. Fryer, el al., Journal of Clinical Investigation (1992) 90:2292-2298; D. B. Jacoby, el al., Journal of Clinical Investigation (1993) 91:1314-1318).
The negative feedback control of acetylcholine release provided by the M.sub.2 muscarinic receptor can be demonstrated experimentally by measuring vagally induced bronchoconstriction in the presence of selective muscarinic agonists or antagonists. Blockade of neuronal muscarinic M.sub.2 receptors with gallamine potentiates vagally induced bronchoconstriction. Conversely, the selective muscarinic M.sub.2 receptor antagonist pilocarpine inhibits irritant-induced cholinergic reflex bronchoconstriction in normal subjects. This inhibitory mechanism is not present in asthmatics because of dysfunctional M.sub.2 receptors (P. A. Minette, et al., Journal of Applied Physiology (1989) 67:2461-2465). Such a defect in muscarinic autoreceptors results in exaggerated cholinergic reflexes in asthma, because the normal feedback inhibition of acetylcholine release is lost.
M.sub.2 receptor dysfunction and subsequent airways hyperreactivity in asthma is thought to be due to increased susceptibility of the receptor to damage by products of the inflammatory response in the airway. Asthma results in an influx of inflammatory cells, especially eosinophils, into the airway. Activated eosinophils in asthmatics secrete a number of injurious proteins, including major basic protein, eosinophil peroxidase, and eosinophil cationic protein. All of these proteins are strongly positively charged. These and other positively charged proteins can cause airway hyperresponsiveness (R. H. Gundel, et al., Journal of Clinical Investigation (1991) 87:1470-1473; A. J. Coyle, et al., American Review of Respiratory Diseases (1993) 147:896-900). Major basic protein (D. B. Jacoby, et al., Journal of Clinical Investigation (1993) 91:1314-1318) and other positively charged proteins (J. Hu, el al. Molecular Pharmacology (1992) 42:311-324) have been shown to function as M.sub.2 muscarinic receptor antagonists. Thus, airways hyperreactivity in asthma is a consequence of direct antagonism of inhibitory M.sub.2 cholinergic receptors by components of airway inflammation.
The treatment of airways hyperreactivity in asthma is currently directed against either inhibiting the airway inflammation leading to release of products that inhibit M.sub.2 receptors, or toward direct reversal of bronchoconstriction of airway smooth muscle. Corticosteroids are the mainstay of anti-inflammatory therapy. Beta-adrenergic agonists, acting by stimulation of beta.sub.2 adrenergic receptors on airway smooth muscle, are used as bronchodilators to directly reverse constricted airways. Nonselective anti-cholinergic drugs such as atropine and ipratropium bromide are available for use as bronchodilators, but block both prejunctional M.sub.2 receptors and M.sub.3 receptors on smooth muscle with equal efficacy. This increases acetylcholine release, overcoming the postjunctional blockade, and makes these nonselective anti-cholinergic agents ineffective at reversing vagally mediated bronchoconstriction. A more specific treatment for reversing the M.sub.2 receptor blockade would be of great benefit as a treatment for the airways hyperreactivity of asthma.
Recently, the anticoagulant drug heparin has been shown to reverse antigen-induced M.sub.2 receptor dysfunction in antigen-challenged guinea pigs (A. D. Fryer, et al., Journal of Clinical Investigation (1992) 90:2292-2298) and to reverse binding of M.sub.2 receptor by major basic protein it vitro (D. B. Jacoby, el al., Journal of Clinical Investigation (1993) 91:1314-1318). Heparin has over the years been suggested as a treatment for asthma (M. M. Hartman, California Medicine (1 963) 98:27-32; D. A. Dolowitz, et al., Annals of Allergy (1 965) 23:309-313; T. Ahmed, el al., American Review of Respiratory Diseases (1992) 145:566-570; T. Ahmed, el al., Journal of Applied Physiology (1993) 74:1492-1498; S. D. Bowler, et al., American Review of Respiratory Diseases (1993) 147:160-163; T. Ahmed, el al., New England Journal of Medicine; International PCT Application, PCT/US93/02880). However, as a treatment for the airways hyperreactivity of asthma, heparin has one great disadvantage: it is an anticoagulant. As such, it would expose the treated patient to an unacceptable risk of hemorrhage, even if treatment was localized by aerosolization of heparin into the lung airway. Aerosolized heparin is well absorbed into the systemic circulation, and administration of heparin by lung aerosolization has been advocated as a method of anticoagulating the blood (L. B. Jaques, el al., Lancet (1976) ii:157-1161).
To use heparin safely as a treatment for the airways hyperreactivity of asthma, it would need to be first inactivated as an anticoagulant without affecting its efficacy to treat asthma. Several chemical methods exist for inactivating heparin as an anticoagulant. Most are based on techniques of chemical desulfation, since it is well established that sulfate groups of heparin are important for anticoagulant activity. However, N-desulfated heparin has been previously reported to be ineffective in the prevention of asthmatic-like bronchoconstriction from aerosolized antigen (T. Ahmed, et al., American Review of Respiratory Diseases (1992) 145:566-570, see FIG. 2). Additionally, N-desulfated heparin has been previously reported to be only 50% as effective as heparin in complement inhibition (J. M. Weiler et al., J.Immunol. (1992) 148:3210-3215; R. E. Edens et al. Complement Today (Cruse, J. M. and Lewis, R. E. Jr. eds): Complement Profiles (1993) 1:96-120).
Thus, the literature teaches that chemical desulfation would not be an effective strategy in modifying heparin for use as an effective treatment for asthmatic airways hyperreactivity. In contrast to what would be predicted by the literature, the present invention discloses that, surprisingly, selective O-desulfation of heparin eliminates the anticoagulant activity of heparin without destroying the ability of heparin to reverse M.sub.2 muscarinic receptor blockade in asthma.
Asthma has been long described in the medical literature as an episodic disease characterized by reversible airways obstruction. This is in contrast to chronic obstructive airways disease from chronic bronchitis and emphysema, in which physiologic airways obstruction is permanent and slowly progressive. However, the characterization of airways obstruction in asthma as episodic and reversible may be simplistic. Clinical pulmonary physicians have recently begun to appreciate a population of asthmatics, usually older individuals, who appear to have unrelenting disease, with lung function that never normalizes between acute bronchospastic episodes. Some of these patients appear to progress to fixed airways obstruction without the presence of other known risk factors such as active or past cigarette smoking. This population presents a difficult clinical challenge, in that many of these individuals are steroid dependent or even relatively resistant to intervention with steroids and other anti-inflammatory or bronchodilator medications.
One possible explanation for this difficult-to-treat population is that patients with chronic asthma undergo remodeling of their airways, with substantial increase in the amount of smooth muscle in airway walls (Heard, B. E., and S. Hossain. 1973. Hyperplasia of bronchial muscle in asthma. J. Path. 110:319-331, James, A. L., P. D. Pare, and J. C. Hogg. 1989. The mechanics of airway narrowing in asthma. Am. Rev. Respir. Dis. 139:242-246; Saetta, M., A. DiStefano, C. Rosina, G. Thiene, and L. M. Fabbri. 1991. Quantitative structural analysis of peripheral airways and arteries in sudden fatal asthma. Am. Rev. Respir. Dis. 143:138-143; Ollerenshaw, S. L., and A. J. Woolcock. 1992. Characteristics of the inflammation in biopsies from large airways of subjects with asthma and subjects with chronic airflow limitation. Am. Rev. Respir. Dis. 145:922-927). Patients dying of asthma have over twice the amount of airway smooth muscle as nonasthmatic subjects (Saetta, M., A. DiStefano, C. Rosina, G. Thiene, and L. M. Fabbri. 1991. Quantitative structural analysis of peripheral airways and arteries in sudden fatal asthma. Am. Rev. Respir. Dis. 143:138-143), and airway smooth muscle hypertrophy is seen in sensitized Brown-Norway rats (Sapienza, S., T. Du, D. H. Eidelman, N. S. Wang, and J. G. Martin. 1991. Structural changes in the airways of sensitized Brown Norway rats after antigen challenge. Am. Rev. Respir. Dis. 144:423-427; Wang, C. G., T. Du, L. J. Xu, and J. G. Martin. 1993. Role of leukotriene D.sub.4 in allergen-induced increases in airway smooth muscle in the rat. Am. Rev. Respir. Dis. 148:413-417) and cats (Padrid, P., S. Snook, T. Finucane, P. Shiue, P. Cozzi, J. Solway, and A. R. Leff. 1995. Persistent airway hyperresponsiveness and histologic alterations after chronic antigen challenge in cats. Am. J. Respir. Crit. Care Med. 151:184-193) after antigen challenge. Increased airway smooth muscle might be expected to change the counterbalance of forces tending to distend or close the airway lumen, thereby altering the location of the equal pressure point, when air is unable to flow (Pride, N. B., S. Permutt, R. L. Riley, and B. Bromberger-Barnea. 1967. Determinants of maximal expiratory flow from the lungs. J. Appl. Phlysiol 23:646-662). Airway wall thickening has also been proposed as a partial explanation for exaggerated changes in airway caliber when airway smooth muscle shortens (James, A. L., P. D. Pare, and J. C. Hogg. 1989. The mechanics of airway narrowing in asthma. Am. Rev. Respir. Dis. 139:242-246). Even small changes in airway wall thickness that have little effect on baseline resistance to airflow can produce an increase in maximal airway responsiveness to agonists, similar to that seen in asthmatics (Moreno, R. H., J. C. Hogg, and P. D. Pare. 1985. Mechanisms of airway narrowing. Am. Rev. Respir. Dis. 133:1171-1180).
The precise stimuli for airway smooth muscle hypertrophy in asthma are unclear, but several possible mitogens for airway smooth muscle have been demonstrated, including endothelin, histamine, the mast cell enzyme tryptase and leukotrienes (Wang, C. G., T. Du, L. J. Xu, and J. G. Martin. 1993. Role of leukotriene D.sub.4 in allergen-induced increases in airway smooth muscle in the rat. Am. Rev. Respir. Dis. 148:413-417; Vitori, E. N., M. Marini, A. Fasoli, R. De Franchia, and S. Mattoli. 1992. Increased expression of endothelin in bronchial epithelial cells of asthmatic patients and effect of corticosteroids. Am. Rev. Respir. Dis. 146:1320-1325; Noveral, J. P., S. M. Rosenberg, R. A. Anbar, N. A. Pawlowski, and M. M. Grunstein. 1992. Role of endothelin-1 in regulating proliferation of cultured rabbit airway smooth muscle cells. Am. J. Physiol. 263(Lung Cell. Mol Physiol. 7):L317-L324; Glassberg, M. K., A. Ergul, A. Wanner, and D. Puett. 1994. Endothelin-1 promotes mitogenesis in airway smooth muscle cells. Am. J. Respir. Cell Mol. Biol. 10:316-321; Panettieri, R. A., P. A. Yadvish, A. M. Kelly, N. A. Rubinstein, and M. I. Kotlikoff. 1990. Histamine stimulates proliferation of airway smooth muscle and induces c-fos expression. Am. J. Physiol 259 (Lung. Cell Mol. Physiol. 3):L365-L371; Ruoss, S. J., T. Hartmann, and G. Caughey. 1992. Mast cell tryptase is a mitogen for cultured fibroblasts. J Clin. Invest. 88:493-499) The polycation protamine is mitogenic for cultured vascular smooth muscle (Edelman, E. R., L. A. Pukac, and M. J. Karnovsky. 1993. Protamine and protamine-insulins exacerbate the vascular response to injury. J Clin. Invest. 91:2308-2313). Therefore, it is also possible that eosinophil-derived positively-charged polycations such as major basic protein might stimulate proliferation of airway smooth muscle.
Equally unclear is how airway smooth muscle remodeling in asthma might be prevented. The bronchodilator salbutamol inhibits proliferation of cultured human airway smooth muscle in response to thrombin and epidermal growth factor (Tomlinson, P. R., J. W. Wilson, and A. G. Stewart. 1994. Inhibition by salbutamol of the proliferation of human airway smooth muscle cells grown in culture. Br. J. Pharmacol. 111:641-647). However, in general, by preventing mast cell degranulation, beta adrenergic agonist bronchodilators may deprive the airway of the anti-proliferative effects of mast cell heparin release, thereby exacerbating smooth muscle remodeling (Page, C.P. 1991. One explanation of the asthma paradox: inhibition of natural anti-inflammatory mechanism by B.sub.2 -agonists. Lancet 337:717-720). In the chronically antigen challenged ovalbumin-sensitized Brown Norway rat, the leukotriene D.sub.4 antagonist MK-571 reduces smooth muscle proliferation of small airways, but was only partially effective in preventing airway remodeling of larger airways (Wang, C. G., T. Du, L. J. Xu, and J. G. Martin. 1993. Role of leukotriene D.sub.4 in allergen-induced increases in airway smooth muscle in the rat. Am. Rev. Respir. Dis. 148:413-417). Because more than one mitogen is likely to promote smooth muscle proliferation in asthmatic patients, it is not surprising that specific blockade of one mediator fails to prevent the remodeling process. For therapy, a treatment is needed that intervenes at a more focal control point in growth regulatory events.
Mast cell heparin has been proposed to normally modulate growth and proliferation of airway smooth muscle (Page, C.P. 1991. One explanation of the asthma paradox: inhibition of natural anti-inflammatory mechanism by B.sub.2 -agonists. Lancet 337:717-720). The closely related sulfated polysaccharide heparan sulfate has been shown to inhibit proliferation of cultured canine tracheal smooth muscle (Panettieri, R. A., P. A. Yadvish, A. M. Kelly, N. A. Rubinstein, and M. I. Kotlikoff. 1990. Histamine stimulates proliferation of airway smooth muscle and induces c-fos expression. Am. J. Physiol. 259 (Lung Cell. Mol. Physiol. 3):L365-L371). Heparin is a potent inhibitor of proliferation of vascular smooth muscle in vitro (Hoover, R. L., R. Rosenberg, W. Haering, and M. J. Karnovsky. 1980. Inhibition of rat arterial smooth muscle cell proliferation by heparin. Cir. Res. 47:578-583) and in vivo (Guyton, J. R., R. D. Rosenberg, A. W. Clowes, and Karnovsky. 1980. Inhibition of rat arterial smooth muscle cell proliferation by heparin. In vivo studies with anticoagulant and nonanticoagulant heparin. Cir. Res. 46:625-634; Clowes, A. W., and M. M. Clowes. 1985. Kinetics of cellular proliferation after arterial injury. II. Inhibition of smooth muscle growth by heparin. Lab. Invest. 42:611-616; Clowes, A. W., and M. M. Clowes. 1986. Kinetics of cellular proliferation after arterial injury. IV. Heparin inhibits rat smooth muscle mitogenesis and migration. Circ. Res. 58:839-845).
Recently, heparin and low molecular weight heparin have been demonstrated by Kilfeather el al. to be potent inhibitors of serum-induced proliferation of bovine tracheal smooth muscle cells in culture (Kilfeather, S. A., S. Tagoe, A. C. Perez, K. Okona-Mensa, R. Matin, and C. P. Page. 1995. Inhibition of serum-induced proliferation of bovine tracheal smooth muscle cells in culture by heparin and related glycosaminoglycans. Brit. J. Pharamcol. 114:1442-1446). In discussing structure-activity implications of their findings, Kilfeather and coworkers suggested that O-sulfation is required for antiproliferative activity in airway smooth muscle cells. Earlier, Wright et al, had shown that increasing the charge of inactive tetrasaccharide fragments by O-oversulfation made them antiproliferative against vascular smooth muscle, whereas reducing the charge of active larger fragments caused them to lose their antiproliferative activity (Wright, T. C., Jr., J. J. Castello, Jr., M. Petitou, J.-C. Lormeau, J. Choay, and M. J. Karnovsky. 1989. Structural determinants of heparin's growth inhibitory activity. Interdependence of oligosaccharide size and charge. J Biol. Chem. 264:1534-1542). Castellot et al, had suggested an absolute requirement for 3-O sulfation as a necessary structural requirement for heparin to inhibit vascular smooth muscle proliferation (Castellot, J. J., Jr., J. Choay, J.-C. Lormeau, M. Petitou, E. Sache, and M. J. Karnovsky. 1986. Structural determinants of the capacity of heparin to inhibit the proliferation of vascular smooth muscle cells. II. Evidence for a pentasaccharide sequence that contains a 3-O-sulfate group. J. Cell Biol. 102:1979-1984). Maccarana et al. reported the importance of 2-O sulfates for heparin binding of the mitogen basic fibroblast growth factor (Maccarana, M., B. Casu, and U. Lindahl. 1993. Minimal sequence in heparin/heparan sulfate required for binding of basic fibroblast growth factor. J. Biol. Chem. 268:23898-23905).
In contrast, the present invention provides the surprising discovery that a selectively 2-O, 3-O-desulfated heparin produced by alkaline lyophilization is a potent inhibitor of fetal calf serum stimulated-airway smooth muscle proliferation.
2-O-desulfated heparin has been reported to be made (R. Rej el al., Thrombosis and Hemostasis (1989)61:540; and M. Jaseja et al., Canadian Journal of Chemistry (1989) 67:1449-1456). Actually, those authors did not recognize that the compound they made was, in fact, 2-O as well as 3-O desulfated heparin. Briefly, the Rej et al. and Jaseja et al. method comprises starting with a heparin solution pH adjusted with 0.1 N sodium hydroxide, which is then lyophilized to produce a 2-O-desulfated alpha-L-iduronic acid residue (and a 3-O-desulfated glucosamine residue). The anticoagulant activity of heparin was studied; however, there was no suggestion of inhibition of airways reactivity or treatment of asthmatic conditions. Likewise, Rej el al. and Jaseja et al. disclosed no activity for 2-O, 3-O-desulfated heparin, and further, did not disclose any effective doses for the compound for any purpose.

Methods of treating asthma with o-desulfated heparin


Data security may be automatically evaluated and adjusted using machine learning and/or satisfiability modulo theories (SMT). In various examples, a machine learning model(s) may be trained using training data that includes samples of customer data labeled with different types of data corresponding to different sensitivity levels of the samples of the customer data. Once trained, this trained machine learning model(s) can be used to classify data that is, or is requested to be, stored in a storage container. A SMT solver(s) may then evaluate the sufficiency of the existing data security (e.g., an existing access policy) of the storage container. Based on the result of the SMT solver's data security evaluation, an action(s) may be taken, such as a remedial action (e.g., adjusting data security of the storage container), a notification action (e.g., sending an alert about the data security deficiency), or the like.

Network-based storage services store data on behalf of customers so that the customers can later access their data on-demand. In order to prevent unauthorized access to the data, an access policy can be applied to a storage container that contains the data and/or to an individual data object within the storage container. Due to the complexity of these access policies, customers often mistakenly apply overly-permissive policies to their storage containers. This is primarily due to the manner in which access policies are defined. In many cases, Identity and Access Management (IAM)-based access controls are used to define an access policy, and such an access policy can include a high number of nested conditions or criteria (e.g., nested "ANDS" and "ORs") that are traversed in real-time in order to determine whether a user attempting to access particular data should be granted access or not. The average customer may find it difficult to understand these types of access policies due to their complexity. This is a concern when highly sensitive data is at stake.
For example, a hospital that is using a network-based storage service to store highly sensitive medical data pertaining to its patients may intend to apply a highly secure access policy to a storage container that stores the medical data, but may mistakenly apply an overly-permissive access policy to the storage container, thereby putting the medical data at risk of unintentional disclosure and/or theft. In some cases, a customer of the network-based storage service may inadvertently store highly sensitive data in a storage container with an overly-permissive access policy, such as one that is open to the general public or to a wide audience of people that should not have access to the highly sensitive data. Moreover, malicious actors may attempt to steal sensitive data, such as personally identifiable information (PII), through hacking and other illicit means. For instance, a malicious actor may attempt to enumerate storage containers with overly-permissive access policies in order to access PII and other sensitive data. These data security issues can result in sensitive data ending up in the wrong hands.
The disclosure made herein is presented with respect to these and other considerations.

Automated data security evaluation and adjustment


The object of the present invention is to provide a process for producing deinked pulp from recovered paper containing stickies while preventing excessive reduction in the size of stickies, lowering the COD of effluents, and producing deinked pulp with a smaller residual ink content.

In response to the recent concern for saving resources or protecting the global environment, recycling of waste paper (old paper) is a social issue and the papermaking industry considers it extremely important to perform enhanced processing of waste paper and expand the use of the recycled paper. In one way to meet this need, the printing ink on the recovered paper is removed by the deinking process to make pulp with a smaller content of residual ink, which is optionally mixed with virgin pulp to make fresh paper.
However, the making of deinked pulp involves one problem with the pulping treatment and the ink detaching treatment; since high shear force is commonly applied under a highly alkaline condition with a pH exceeding 10, the contaminants in the waste paper such as a pressure-sensitive adhesive, a bonding agent, adhesive tape, spine glue on magazines, and vinyl tape become so small in size that it is very difficult to remove them completely even if the deinked pulp is subjected to the subsequent fine screening process as by a screen or a cleaner. If the deinked pulp contains such micronized contaminant, papermaking from that deinked pulp will suffer, for example, a runability problems such as sheet breaks or a deterioration in paper quality due to contamination of the paper with the sticky contaminants. The exertion of high shear force under the alkaline condition causes other difficulties, such as an increased chemical oxygen demand (COD) in the effluent, damaged pulp fibers that have a lower water freeness which results in less efficient paper machine runability, and the formation of pulp that has lower bulk and which is poor in optical characteristics.
Japan TAPPI Journal vol. 49(1), 121-130 (Non-Patent Document 1) proposes a method in which recovered paper is pulped at low temperature under a neutral condition to prevent stickies from becoming undesirably small in size and, after removing the stickies with a screen or by other suitable means as it remains large enough, ink is detached under a highly alkaline condition. This method is anticipated to provide some improvement as regards the stickies but, on the other hand, since the pulp is subjected to high shear force under the highly alkaline condition, there is no anticipation for lower COD.
To deal with these problems, a method has been proposed in which the use of alkali chemicals in the making of deinked pulp (DIP) is sufficiently reduced to establish a neutral condition, whereby the stickies present in waste paper are prevented from becoming unduly small in size and, what is more, the COD in the effluent is reduced. However, the reduced use of alkali chemicals lowers the detachability of ink, eventually deteriorating the quality of the pulp as the final product. To cope with this problem, the official gazette of JP 11-200269 A (Patent Document 1) proposes a method in which recovered paper swelled under an alkaline condition is neutralized with an added acid and after neutralization or simultaneously with it, high shear force is applied, whereby DIP with a smaller content of residual ink is produced while reducing the COD of effluents from the DIP production process. However, the use of an acid to neutralize the alkali-swelled waste paper adds to the overall cost.
The official gazette of U.S. Pat. No. 3,260,211 (Patent Document 2) shows a crystalline silicate having a deinking capability. However, this document does not show using the silicate in a weakly alkaline to neutral region, or a condition where deinking is generally difficult to perform.    Patent Document 1: Official gazette of JP 11-200269 A    Patent Document 2: Official gazette of U.S. Pat. No. 3,260,211    Non-Patent Document 1: Japan TAPPI Journal vol. 49(1), 121-130

Abstract: In the ink detachment stage of the process for producing deinked pulp from recovered paper containing stickies, an anhydride of crystalline layered silicate is added, preferably in an amount of 0.1-1.5 weight % of absolute-dry pulp, and a deinking treatment is performed at a pH of 7.0-9.9. In the present invention, the deinking treatment is performed in a weakly alkaline to neutral region which is generally said to be effective in reducing the amount of stickies but less effective in ink detachment and, yet, deinked pulp having a smaller amount of residual ink can be produced.


In an ink ejection type recording device in which expansion of bubble ejects an ink droplet from a nozzle toward a recording medium, a heater formed in an ink channel is applied with a pulse of voltage by a driver circuit. The pulse of voltage is determined so that the surface of the heater in direct contact with the water-based ink is rapidly heated to a temperature causing to invoke caviar-wise nucleation of the ink that is in direct contact with the surface of the heater. Expanding bubbles resulting from the caviar-wise nucleation ejects an ink droplet from the nozzle, wherein the heater is heated at a heating speed in a range from 1.times.10.sup.8 .degree. C./sec to 5.times.10.sup.8 .degree.C./sec, and the surface of the heater is heated up from a room temperature to a temperature substantially equal to 320 C within a period of time ranging from 0.6 to 3 .mu.sec. By heating the heater under these conditions, the ink in contact with the heater starts boiling with a high boiling pressure, the generated bubble has a large volume, and thus the bubble can generate pressure sufficiently large to eject the ink droplet.

1. Field of the Invention
The present invention relates to an ink jet recording device that uses heat energy for ejecting ink droplets toward a recording medium. The invention further relates to a method of driving the ink jet recording device.
2. Description of the Related Art
Japanese Laid-Open Patent Publication Nos. SHO-48-9622, SHO-54-51837, SHO-54-59936, SHO-54-161935 describe a type of ink jet recording device with channels filled with ink and nozzles, each in fluid communication with an ink channel. A pulse of heat is applied to the ink, which rapidly vaporizes as a result. The expansion of the resultant vapor bubble ejects a droplet of ink from the corresponding nozzle.
The most effective method of producing the heat pulse is with a thin film thermal resistor provided in the ink channel. Practical examples of thin film thermal resistors are described at page 58 of the "Nikkei Mechanical", published Dec. 28, 1992 and the "Hewlett-Packard Journal" published August 1988. These thermal resistor commonly include a thin film resistors with great thermal endurance, a metal thin film conductor, and a two-layer protective covering over the thin film resistor and the metal thin film conductor. The thin film forming the thin film resistors is about 0.1 .mu. thick. The two-layer structure of the protective covering is about 3 to 4 .mu. thick in total. The first layer of the protective covering is in contact with the thin film resistor and the metal thin film conductor and is for protection against oxidation and electrochemical corrosion. The second protective layer is provided for protecting the first protective layer against damage from cavitation.
Thermal resistors constructed as described above are used to pulse heat and rapidly vaporize the portion of the ink adjacent to the thermal resistor. Ink droplets are ejected by expansion of the resultant bubble. Printers must be able to rapidly repeat the ejection process which includes not only expansion of bubbles, but also the contraction and final disappearance of bubbles. Four conditions are required to produce a printer that can eject ink droplets stably and rapidly in succession at a high frequency.
The first condition relates to the generation of bubbles. Japanese Laid-Open Patent Publication Nos. SHO-55-27282 and SHO-56-27354 teach that in order to increase ejection efficiency, response, and frequency characteristics, the temperature at the surface of the thermal resistor must be rapidly increased to thereby invoke film boiling in the ink in contact with the thermal resistor, and the processes A through E shown in FIG. 1, which show the boiling characteristic curve of water, should be kept as short as possible. However, there are two points in the technical explanation and understanding in these publications which need correction.
The first point to be corrected is that the boiling characteristic curve shown in FIG. 1 represents a set stable state whereas ejection of ink droplets occurs in an unstable state. In the boiling characteristic curve shown in FIG. 1, the temperature at the heater surface that contacts the water is stable or rises and lowers slowly. Boiling which occurs from application of a pulse of heat is unsteady boiling. In fact, in subsequent research (see page 7 of Collection of Presentations from the 22nd Japan Thermal Transmission Symposium 1985-5), the inventors of the above-listed applications disclose that test bubbles were generated at 263.degree. C. This temperature matches the superheating limit of 270.degree. C. predicted by the theory of spontaneous nucleation. That is, bubbles are generated by unstable boiling, which is a very different phenomenon from the phenomenon of stable boiling represented in FIG. 1.
The second point to be corrected is the inappropriate use of the term film boiling. Film boiling assumes that conditions continue for a certain length of time. However, an extremely short pulse of heat rapidly generates a single bubble that vanishes in an extremely short period of time. In later research (see page 7 of the Collection of Presentations from the 22nd Japan Thermal Transmission Symposium 1985-5, on page 247 of the Collection of Presentations from the Journal for the 23rd Japan Thermal Transmission Symposium 1986-5, and on page 253 of the Collection of Presentations from the Journal for the 25th Japan Thermal Transmission Symposium 1988-6), the inventors of the above-listed applications changed their opinions to say that a small bubble is formed from spontaneous nucleation (also referred to as heterogenous nucleation) at a portion of the heater surface and afterward rapidly expands to the entire surface of the heater.
Therefore, it is technically incorrect to say that in order to increase ejection efficiency, response, and frequency characteristics, the temperature at the surface of the thermal resistor must be rapidly increased to thereby invoke film boiling in the ink in contact with the thermal resistor, and the processes A through E shown in FIG. 1, which shows the boiling characteristic curve of water, should be kept as short as possible. Taking the two points into consideration, a more accurate statement would be that the ink in contact with the surface of the heater should be brought into a film boiling condition in as short a time as possible.
Japanese Laid-Open Patent Publication No. HEI-03-266646 describes a thermal ink jet print head which uses a boiling phenomenon appearing when ink is heated under conditions different from those in the above-described research. The surface of the heater is raised at a speed of 10.sup.6 to 10.sup.9 .degree. C./S and the heat flux from the heater surface to the ink is set at 10.sup.7 to 10.sup.8 W/m.sup.2. The temperature at the heater surface and the ink adjacent to the heater surface is rapidly heated to the temperature at which homogeneous nucleation occurs. Ink is ejected by a homogeneous nucleated bubble.
The type of boiling that is ordinarily observed occurs by vapor nucleation. For example, vapor nucleation occurs at defects in the solid surface in contact with water when the temperature of the water reaches about 100.degree. C.
Spontaneous nucleation occurs when no defects are present in the solid surface in contact with the liquid to be boiled, that is, when the solid surface is perfectly uniform. Boiling activated by spontaneous nucleation occurs simultaneously over the entire boundary between the solid surface and the liquid. When the liquid to be boiled is water, boiling will start only when the temperature at the solid surface reaches about 270.degree. C. Spontaneous nucleation is also referred to as non-homogeneous nucleation because thus activated boiling occurs where solid and liquid coexist.
Homogeneous nucleation occurs only in superheated homogeneous liquids in contact with a uniform solid surface, as described above for spontaneous nucleation, that is rapidly heated. Refer to V. P Skripove, Metastable Liquids, John Wiley, New York 1974. The temperature at which homogeneous nucleation is assumed to occur in water is 312.5.degree. C. However, it is technically difficult to produce a heater which can generate the extremely rapid increase in temperature necessary for homogeneous nucleation to occur. In fact, there has been no confirmation of an actual heater with this capability.
Homogeneous nucleation is termed homogeneous, despite the presence of a solid surface, because homogeneous nucleation can be observed only in homogeneous liquids. Boiling begins in water adjacent to the boundary between the liquid and the solid surface when critical values for both the speed at which the solid surface rises and the heat flux that is transmitted to the liquid from the solid surface are exceeded and when the temperature at the solid surface and the water adjacent to the solid surface exceeds 312.5.degree. C.
Recently, Iida et al experimentally verified this phenomenon as discussed on page 334 of Collection of Presentations from the 27th Japan Thermal Transmission Symposium 1990-5. The invention described in Japanese Laid-Open Patent Publication No. HEI-03-266646 is based on the results of these experiments, in which the thermal resistor and the electrode are formed from the same material. However, the width of the electrode is at least five times and up to ten times the width of the thermal resister. This makes manufacturing an inexpensive large-scale line head difficult, although a head with a low density of 30 dpi could possibly be produced. That is, using this thermal resistor in a high density multi-nozzle type ink jet print head would be impossible without adding some further contrivance.
The second condition relates to the speed at which the thermal resistor is heated. Japanese Laid-Open Patent Publication No. SHO-55-161664 teaches that the average speed at which temperature of the thermal resistor increases (hereinafter referred to as "average speed of temperature increase") should be 1.times.10.sup.6 .degree. C./sec or more, preferably 3.times.10.sup.6 .degree. C./sec or more, and optimally 1.times.10.sup.7 .degree. C./sec or more. The liquid described in the publication is ink made mainly from ethanol. Recently, Iida et al performed precise experiments using pure ethanol. The average speed of temperature increase and the number of bubbles generated during these experiments are described in detail on page 712 of Collection of Presentations from the 28th Japan Thermal Transmission Symposium 1991-5. Although some discrepancies in the data can be accounted for by differences between pure ethanol and ink made mostly from ethanol, the most noteworthy result is that bubbles were generated at a density, which most closely governs ejection of ink, that was two orders of magnitude greater in ethanol than in water at the same average speed of temperature increase. That is, in order to generate the same number of bubbles in the same density, water must be heated at an average speed of temperature increase that is ten times faster than the average speed of temperature increase required for ethanol.
Therefore, a great technological leap is required to apply the invention described in Japanese Laid-Open Patent Publication No. SHO-55-161664 to water-based ink. An extremely fast average speed of temperature increase of about 1.times.10.sup.8 .degree.C./sec or more is required to stably eject water-based ink.
The average speed of temperature increase of 3.times.10.sup.7 .degree. C./sec could attained as reported on page 247 of the 23rd Japan Thermal Transmission Symposium Collection of Presentations 1986-6, and 7 to 8.times.10.sup.7 .degree. C./sec on the 25th Japan Thermal Transmission Symposium Collection of Presentations 1988-6. Further, the ink jet printers normally operate with 5 .mu.sec of heating pulse width. The thin film thermal resistor needs to be heated up to about 300.degree. C., so that the average speed of temperature increase in the ink jet printers is 300/(5.times.10.sup.-6)=6.times.10.sup.7 .degree. C./sec. Because the thin film thermal resistor used therein is covered with a protective layer of about 4 .mu.m on its surface, the speed of temperature increase on the surface of the thermal resistor contacting the ink would be slightly slower than the speed as calculated above.
When the average speed of temperature increase is further increased, it is confirmed that caviar-wise nucleation occurs in pure water as is theoretically predicted (See the 27th Japan Thermal Transmission Symposium Collection of Presentations 1990-5, page 334 and Presentation Papers published from Japan Mechanical Society, vol. B60, No. 572 (1994-4), page 264. In these reports, experiments were performed using a heater with no protection layer and the average speed of temperature increase of 9.3.times.10.sup.7 .degree. C./sec was attained.
Japanese Laid-Open Patent Publication No. HEI-3-266646 discloses that good ink ejections are performed when the average speed of temperature increase is in a range from 10.sup.6 to 10.sup.9 .degree. C./sec or more.
The third condition relates to the time between when the heat pulse starts and when the liquid starts to boil (hereinafter referred to as "the time to boiling start"). Asai et al discloses use of a naked heater without protective layers (page 7 of the Collection of Presentations from the 22nd Japan Thermal Transmission Symposium 1985-5). Although the lack of protective layers improves the rate of heat transmission, it also reduces reliability. Asai et al described tests using ethanol. Bubbles can be generated in ethanol at a temperature 70.degree. C. less than the temperature for generating bubbles in water. Asai et al used strobe techniques to observe the time between when a bubble was generated to when the bubble disappeared. Results of these observations are schematically shown in FIG. 2. Times listed indicate time elapsed after the initiation of a 10 .mu.S heat pulse. As can be seen, generation of the bubble begins 4 .mu.S after start of the thermal pulse. The bubble is at its maximum size at about 8 .mu.S after start of the thermal pulse. Afterward the bubble begins to contract. Secondary bubbles are generated after the first main bubble until the last secondary bubble completely vanishes at about 20 .mu.S after start of the heat pulse.
Asai et al describes using a heater similar to the above-described naked heater, but with a two-layer protective structure covering the alloy thin film resistor, in order to generate bubbles in water, which has nearly the same qualities as water-based ink (page 247 of Collection of Presentations from the 23rd Japan Thermal Transmission Symposium 1986-5). The results of the test are shown in FIG. 3. Power was applied so that the generation of a bubble begins at the declining edge of the thermal pulse (that is, when application of power is stopped). With this type of heater covered with the two-layer protective layer, 7 .mu.S was required from when generation of the bubble began to when the bubble reached its maximum size. This time is fixed and independent of the duration of the thermal pulse. No data was provided for time required for the bubble to disappear. However, because generation of secondary bubbles, which is a phenomenon similar to the bubble rebound phenomenon observed during cavitation, can also be observed when the pulse width of the thermal pulse is 10 .mu.S long, it can be assumed that bubbles begin to disappear about 25 to 30 .mu.S after start of bubble generation.
Asai et al discloses results of generating a bubble in actual water-based ink using a heater covered with the two-layered protective structure (page 253 of the Collection of Presentations from the 25th Japan Thermal Transmission Symposium 1988-6). Microscopic bubbles appeared at a portion of the heater surface at approximately 3 .mu.S after the start of the heat pulse. Afterward, a bubble was generated over the entire surface of the heater. Asai et al did not measure the temperature at the surface of the heater nor the heat flux to the liquid in tests of the third condition.
In contrast to this, Iida et al performed tests to accurately measure these values (see page 334 of Collection of Presentations from the 27th Japan Thermal Transmission Symposium 1990-5). Iida et al heated water using a heat pulse with duration of 5 .mu.S or more. Initial boiling nucleation in water was observed using a strobe light with an extremely short pulse of 10 nanoseconds. The shortest boiling start time was about 3.7 .mu.S. Theoretically predicted parameters of average speed of the temperature increase and the average speed of heat flux match with the conditions observed before and after the start of boiling. Two experiments and the results of the experiments are discussed below.
(1) In one experiment, heat was applied to 20.degree. C. water at an average speed of temperature increase of 0.56.times.10.sup.8 .degree. C./sec or greater and with an average heat flux of 1.5.times.10.sup.8 W/m.sup.2 or greater. The temperature at the surface of the heater at the start of boiling matched the theoretical temperature (312.5.degree. C.) at which homogeneous nucleation is believed to occur in water at atmospheric pressure. It was determined that boiling caused by this type of rapid heating is independent of the degree of liquid subcool (that is, the difference between the bulk temperature and the temperature at the surface of the heater when boiling starts).
(2) In another experiment, heat was applied at an average speed of temperature increase of 0.70.times.10.sup.8 .degree. C./sec or greater and with an average heat flux of 2.1.times.10.sup.8 W/m.sup.2 or greater, whereupon boiling caused by caviar-wise nucleation was observed for the first time in water. It should be noted that boiling did not occur by caviar-wise nucleation when; average speed of temperature increase or the average heat flux was less than these values. The characteristics of caviar-wise nucleation as observed in the above experiment are that first a multiplicity of small bubbles with a uniform size are generated across the entire surface of the heater at a uniform distribution. The number of bubbles rapidly increases. The bubbles couple to form a bubble film at the surface of the heater.
Contrarily, in normal homogeneous nucleation, small bubbles are generated erratically on the surface of the heater. The bubbles enlarge and couple to form the bubble film. The time period from nucleation to formation of the bubble film is much slower in normal homogeneous nucleation than in caviar-wise nucleation, which requires only 1 .mu.S or less. Although the time period from nucleation to formation of the bubble film has not been measured in spontaneous nucleation (heterogenous nucleation), considering that the speed of temperature rise and the heat flux are comparatively small values, the speed of formation is probably fairly slow.
In summary, the speed from the start of boiling to formation of a bubble film is slowest in spontaneous nucleation, faster in homogeneous nucleation, and fastest in caviar-wise nucleation. The shortest observed example of time from heat pulse to boiling is about 3 .mu.S. This can be estimated as the limit for conventional thermal resistors which require a thick two-layer protective covering.
The fourth condition for allowing stable ejection of ink at a high repetition speed relates to the contraction and disappearance of bubbles. There have been many attempts to control the speed at which bubbles contract and disappear in order to smooth recuperation of the meniscus after ejection and moreover to shorten the frequency and increase the speed of ejections. For example, Japanese Laid-Open Patent Publication No. SHO-55-132267 describes setting the duration of time required for the surface of the heater to cool to longer than the time required to heat the surface of the heater. Japanese Laid-Open Patent Publication Nos. SHO-55-161662, SHO-55-161663, and SHO-56-13177 describe setting the time required for the temperature at the surface of the heater to cool by half to a duration of time longer than the time required to heat the surface but shorter than four times the time required to heat the surface. However these publications do not accurately disclose data or the technical basis for these determinations. Additionally, the technical content and results of controlling the speed of bubble contraction and disappearance is questionable.
Publications by Asai and others refute these inventions (Collection of Presentations from the 22nd Japan Thermal Transmission Symposium 1985-5 and in Collection of Presentations from the 23rd Japan Thermal Transmission Symposium 1986-5). A film shaped bubble generated on the heater by application of a pulse of heat expands explosively at high pressure (several tens to hundreds of atmospheres) and at high temperature (about 300.degree. C.). Expanding gas in the bubble is cooled by the surrounding room temperature liquid, i.e., the ink. When the bubble is at its maximum size, the interior of the bubble is almost a complete vacuum. In the next instant, the bubble begins to contract, and vanishes in about 5 .mu.S. The heat flux from the surface of the heater to the bubble is negligible when the heater is covered by the bubble. Therefore, the speed of contraction is virtually constant and independent of the temperature at the surface of the heater.
However, when the temperature at the surface of the heater does not decrease even after the initial bubble disappears, secondary bubbles are repeatedly generated. Generation of secondary bubbles interferes with recuperation of the meniscus after ink is ejected. Inducing boiling by heating a portion of a liquid that is cooler than boiling temperature is termed subcool boiling. Thermal ink jet print heads use subcool boiling when the amount of subcooling is large. As can be seen in FIG. 3, the time required for a bubble to contract and disappear is twice as long as the time required to generate the bubble. Before a bubble is generated, a pulse of heat with long duration (10 to 50 .mu.S) is applied to heat the water on the heater, to increase the volume of water that boils as a result, and to increase the volume of the bubble. The time for contraction of the resultant large volume bubble is about 10 .mu.S. Whether the secondary generation of bubbles shown in FIG. 3 results from insufficient cooling of the heater temperature or from cavitation by the contraction of the bubble volume is unknown, but secondary generation of bubbles occurs in all bubble contractions in conventional technology.
In Japanese Laid-Open Patent Publication Nos. SHO-55-27281 and SHO-55-27282, Asai et al teaches that the rise in temperature of the heater and the subsequent cooling speed should be as rapid as possible. The only fixed quantity mentioned however is an extremely long pulse of 100 .mu.S.
In order to increase the frequency or ejections and provide stable ejection at the same time, boiling must be started as quickly as possible after application of the energy pulse to the thermal resistor and also the expanded bubble must be caused to disappear as rapidly as possible. Conventional technology requires that thin film resistors include a two-layer protective coating. Such thin film resistors require at least 3 .mu.S from after start of application of the energy pulse to when the film boiling begins. Even naked thin film thermal resistors with no protective layers, which are unreliable and impractical, require at least 4 .mu.S to generate bubbles in ethanol. Bubbles require 30 .mu.S or more to disappear from start of the pulse application with thin film thermal resistors with two-layer protection coverings. Bubbles generated by naked thermal resistors in ethanol require 20 .mu.S or more to disappear. Secondary bubbles are also always generated. Secondary generation of bubbles increases the time required for bubbles to disappear, thereby interfering with efforts to increase the frequency of ejections. A large amount of energy, that is, about 17 .mu.J/50.times.50 .mu.m.sup.2 or more, is required to start boiling with film thermal resistors with two-layer protective coverings. Although details will be explained later in the embodiment of this application, only several .mu.J/50.times.50 .mu.m or less of energy are required to start boiling by a protection-layerless thin film thermal resistor. Therefore, almost all of the energy applied to conventional heaters is used to heat the substrate. For this reason, the surface of the heater is hot while the bubble is vanishing. This is a major source of secondary bubble generation. Heating of the substrate is brought about by the material from which the ink channel is produced and the temperature of the ink. This is a source of unstable ink ejection.
Referring back to the second condition relating to the speed at which the thermal resistor is heated, it is technically difficult to increase the average speed of temperature increase. In fact, there is few reliable experimental reports on the average speed of temperature increase of more than 1.times.10.sup.8 .degree. C./sec. Japan Hardcopy '94 Presentation, 1994-6, page 141 is one example of the report. Nevertheless, it has been considered that the faster the speed at which the thermal resistor is heated, the more effective in performing ink ejection.
In order to increase the average speed of temperature increase, it is essential to employ a heater in which a protective layer is not provided on the surface of the thin film thermal resistor. Even if the protective layer is provided thereon, its thickness must be as thin as possible, that is, about 100 .ANG..

Ink jet print head and a method of driving ink therefrom


A high-frequency surgical generator including a power supply for supplying rectified electrical energy, a power oscillator for supplying a potential-free, DC current-free and DC voltage-free high frequency voltage and a control device for controlling the high frequency voltage wherein the power supply is configured as a current source for supplying a load-independent output current, such that the load-independent output current of the power supply serves as the control variable for controlling the high-frequency voltage. The target value of the load-independent output current is pre-determined by the control device. The high-frequency surgical generators configured as such achieve improved modulation capability.

High-frequency surgical devices are increasingly being used in surgery. The generators employed for this purpose supply a fundamental frequency, which typically lies in the range of 300 kHz to 4 MHz. In the generators, power oscillators are provided which rectify and convert electrical energy provided from the main supply network into a potential-free, DC voltage-free output voltage having the aforementioned fundamental frequency. In very many applications, such as high voltage coagulation or coagulating cutting, this fundamental frequency is overlaid with a 'modulation frequency', which is typically in the order of 50 kHz. A limited number of sinusoidal oscillations (in an extreme case, a single sinusoidal oscillation) is to be generated, followed by a pulse pause without any energy transfer. Following expiration of a modulation period, the provision of a pulse packet begins again.
It is evident from this that spontaneous starting of the output voltage is required. This means that after 1 or, at most 2, half-periods, the output voltage must have reached its end value, since this influences the effect being striven for on the tissue being treated.
Usually, the energy conversion described is brought about in two successive steps, as illustrated by FIG. 7. First, the electrical energy supplied from the main 1 is rectified by a rectifier 2, so that a constant DC voltage is made available. This constant DC voltage is converted by a power supply 3 (a DC/DC converter) into an intermediate circuit voltage UZ. This intermediate circuit voltage UZ is adjustable. This first energy conversion unit will be referred to in the following as the power supply.
Connected thereto is a second energy conversion unit, which will be referred to in the following as the power oscillator 10. The power oscillator 10 is an inverter, which also includes a potential separation from the patient circuit. The output terminals of the power oscillator 10 are connected, on one side, to an electrosurgical instrument 4 and, on the other side, to a neutral electrode 5. Also connected to the output terminals of the power oscillator 10 is an actual-value sensor 22, which detects the voltage at the output of the power oscillator 10 and compares said voltage with a target voltage from a setpoint generator 21, whereupon the system deviation is fed back to the power supply 3 via a controller 20, so that the intermediate circuit voltage UZ is adjusted such that the output voltage amplitude of the power oscillator 10 is controlled according to the setting of the setpoint generator 21.
As shown in FIGS. 8 and 9, the power oscillator 10 usually includes a driving circuit 11 with power semiconductor devices, a transformer 12, which is enhanced with a parallel connected capacitance CP into a parallel resonant circuit and, at the output of the transformer 12, a series circuit including an inductance LSA and a capacitance CSA, that is, a series resonant circuit toward the patient circuit. In the conventional embodiment shown in FIG. 9, a further series resonant circuit including an inductor LSE and a capacitor CSE is also provided between the output terminals of the driving circuit 11 and the parallel resonant circuit comprising the transformer 12 and the parallel capacitance CP.
In order to ensure the best possible modulation capability and therefore the spontaneous starting of the oscillation of the output voltage, the input series resonant circuit (as per FIG. 9) is often dispensed with (as shown in FIG. 8). The input of the overall resonant circuit is therefore a parallel resonant circuit. Since the driving circuit is also fed from a voltage source, specifically an output capacitance CA of the power supply 3, the driving power semiconductor device 11 represents a short-circuit between a charged capacitor (CA) and an uncharged capacitor (CP). The consequence thereof is that the size of the current flowing is determined only by parasitic manifestations such as lead inductances and path resistances of the semiconductor devices. Since these parasitic values are usually small compared with the actual component values, very high undefined electrical current values arise. These, often very high, pulsed currents can emit undesirable electromagnetic interference (which is not permissible in clinical environments). In addition, the dimensioning of the power semiconductor devices of the driving circuit 11 is often uneconomic.
In order to solve this problem, the circuit shown in FIG. 9 is used, wherein the driving currents are determined by an input inductance LSE. However, this brings with it the disadvantage that the filter does not start to oscillate spontaneously and is therefore not suitable for the aforementioned modulation.


Methods and apparatus for measuring and controlling the flow rates of processing solutions to a CMP machine during the polishing and planarization process. The apparatus comprises a processing solution source, a processing solution dispensing system for applying the solution to the CMP machine, a mechanism for transferring the processing solution from the solution source to the dispensing system, and a metering or sensing system for accurately measuring the amount of processing solution actually dispensed to the CMP machine. Preferably, the metering system comprises a coriolis mass flow meter and a controller for controlling its operation. The metering system may interface with the CMP machine controller in a feed-back loop configuration so that the actual flow rates of the solutions may be controlled in real time.

The production of integrated circuits begins with the creation of high-quality semiconductor wafers. During the wafer fabrication process, the wafers may undergo multiple masking, etching, and dielectric and conductor deposition processes. Because of the high-precision required in the production of these integrated circuits, an extremely flat surface is generally needed on at least one side of the semiconductor wafer to ensure proper accuracy and performance of the microelectronic structures being created on the wafer surface. As the size of the integrated circuits continues to decrease and the density of microstructures on an integrated circuit increases, the need for precise wafer surfaces becomes more important. Therefore, between each processing step, it is usually necessary to polish or planarize the surface of the wafer to obtain the flattest surface possible.
For a discussion of chemical mechanical planarization (CMP) processes and apparatus, see, for example, Arai, et al., U.S. Pat. No. 4,805,348, issued February, 1989; Arai, et al., U.S. Pat. No. 5,099,614, issued March, 1992; Karlsrud et al., U.S. Pat. No. 5,329,732, issued July, 1994; Karlsrud, U.S. Pat. No. 5,498,196, issued March, 1996; and Karlsrud et al., U.S. Pat. No. 5,498,199, issued March, 1996.
Such polishing is well known in the art and generally includes attaching one side of the wafer to a flat surface of a wafer carrier or chuck and pressing the other side of the wafer against a flat polishing surface. In general, the polishing surface comprises a horizontal polishing pad that has an exposed abrasive surface of, for example, cerium oxide, aluminum oxide, fumed/precipitated silica or other particulate abrasives. Polishing pads can be formed of various materials, as is known in the art, and which are available commercially. Typically, the polishing pad may be a blown polyurethane, such as the IC and GS series of polishing pads available from Rodel Products Corporation in Scottsdale, Ariz. The hardness and density of the polishing pad depends on the material that is to be polished.
During the polishing or planarization process, the workpiece or wafer is typically pressed against the polishing pad surface while the pad rotates about its vertical axis. In addition, to improve the polishing effectiveness, the wafer may also be rotated about its vertical axis and oscillated back and forth over the surface of the polishing pad.
Also, during the polishing of planarization process, a slurry solution is typically introduced onto the polishing surface, adding the chemical component to the chemical mechanical planarization ("CMP") process. Various different types of slurry solutions may be used to polish the semiconductor wafers, most of which are available commercially from various sources, such as, for example, Rodel, and Cabot. The type of slurry used generally depends on the material layer of the wafer being polished. For example, one type of slurry may be used to polish a bare silica surface of a wafer, while other types of slurries may be used to polish an oxide dielectric layer or a metal conductor layer. Moreover, deionized water is very often introduced into the system for cleaning purposes.
One of the more costly aspects of the wafer polishing process surrounds the consumption and disposal of the slurry compounds and the deionized water. It is therefore advantageous to precisely monitor and control the amount of slurry and deionized water used during the semiconductor wafer fabrication process. However, given the nature of the slurry compounds, no device to date has been found that accurately and clearly measures slurry flow. For example, standard flywheel and rotor type meters are inadequate because the fine abrasive particles in the slurry solutions tend to damage and jam the mechanical components of those meters. In addition, as the abrasive particles wear on the mechanical components of the meters, particulates worn from the components can contaminate the slurry, causing extreme damage to the wafers. Therefore, a noncontacting fluid sensing device is considered desirable.
Various types of noncontacting fluid sensing devices are generally known in the art, including electromagnetic flow meters, ultrasonic flow meters, thermal dispersion flow detectors and meters, vortex shedding meters, and rotameters with Hall effect electronic transducers, to name a few. However, most are inadequate for measuring the slurry flows in a CMP environment.
Electromagnetic flow meters are typically used in the mining industry to detect the large slurry flows used in that industry. As such, the electromagnetic flow meters are generally too large to be used with the CMP machines. Ultrasonic flow meters, like electromagnetic meters, are also too large for practical use with CMP machines. In addition, ultrasonic flow meters need to be fully charged with fluid in order to operate. This condition greatly affects the accuracy of the meter at the beginning and end of slurry flow cycles. Thermal dispersion flow detectors and meters have very slow response times, typically fifteen to twenty-five seconds; this is far too slow to accurately measure slurry flow rates in CMP machines. In addition, thermal dispersion flow detectors and meters are ineffective when used to detect the low slurry flow amounts that exist in CMP machines. Similarly, the vortex shedding meters also cannot adequately detect the low flow ranges of the CMP machines. Finally, the rotameters with Hall effect electronic transducers are inadequate because the meter's electronics are unstable, and the meter's sensors are ultra-sensitive to any metallic object they come in contact with. For example, the sensor can waiver up to ten percent (10%) when a metal object passes close to it. This condition is totally inadequate for use on a CMP machine where metal parts are prevalent.
A system is thus needed which accurately measures the flow rates of slurry and deionized water to the CMP machine and controls the flow rate during the CMP process which overcomes the shortcomings of the prior art.

Methods and apparatus for measuring and dispensing processing solutions to a CMP machine


The present invention includes an improved method to detect and quantitatively assay the amount of DNA damage in large double-stranded templates starting with less than 50 ng of sample DNA. This invention has utility in vivo for quantitating gene-specific DNA damage, measuring DNA repair rates and monitoring efficacy of anti-neoplasia therapy in patients. Additionally, this invention is useful to detect and assess risk due to mutagenic environmental hazard sites, and monitor hazard site dynamics and includes a device for accomplishing these objects.

Organisms are being constantly bombarded by endogenous and exogenous genotoxic agents which injure their DNA. This DNA damage, if left unrepaired, can lead to cell death, somatic mutations or cellular transformation, which at the organismal level can result in cancer, aging, and decreased immunocompetency. There is now a large amount of evidence which indicates that the repair of specific DNA lesions does not occur equally throughout the entire genome. For example, it has been shown that the DNA of actively transcribed regions is repaired more efficiently than DNA of inactive regions. This gene-specific DNA repair is due mainly to the rapid repair of the transcribed strand of actively expressed genes (Mellon et al., 1987; Mellon and Hanawalt, 1989; Smerdon and Thoma, 1990), and as a consequence can lead to the accumulation of mutations in the more slowly repaired non-transcribed strand (Chandrasekhar and Van Houten, 1994).
Preferential repair of DNA damage in actively transcribed genes was initially identified using a Southern hybridization-based assay employing T4 endonuclease V, which specifically cleaves DNA at pyrimidine dimer sites (Bohr and Okumoto, 1988). While this methodology has proven useful in the identification and study of gene-specific repair, it has the serious disadvantage of requiring a lesion-specific endonuclease to incise the DNA near the damaged nucleotide. Other disadvantages including:
the requirements of relatively large amounts of starting sample DNA; and PA1 the need for specific restriction sites flanking the DNA region of interest.
Another approach to determining DNA damage and repair in specific genomic DNA regions is the Taq enzyme and polymerase chain reaction (PCR) method of Govan et al., (Govan et al., 1990). This method is based on the fact that many DNA lesions can block Taq DNA polymerase, which causes in a decrease in amplification product. The method of Govan et al., however, was not very powerful because of the small size limitation on the DNA segments being amplified--less than 450 bp. Subsequently, the sensitivity such assays was increased to DNA segments of about 2 to 3 kb (Jennerwein and Eastman, 1991; Kalinowski et al., 1992). Presently the detection of DNA damage in specific gene sequences of bacterial and mammalian cells is limited to the quantitation of amplification products ranging in size from 334 bp to 3.2 kb.
Limitation on the Sensitivity of Prior Art Amplification Assays
Current PCR assay methods are not sufficient to detect DNA damage after exposure to biologically and environmentally relevant doses of genotoxic agents, including ionizing radiation. While the current PCR-based assay for the detection of DNA damage appears to be useful at high doses of damaging agent, it suffers from lack of sensitivity at biologically relevant doses, and therefore can not be used reliably for accurate DNA damage detection and determining DNA repair rates in humans. This is a major problem as the art currently stands. To meet these needs, the sensitivity of a DNA damage detection assay must be increased from a current detection limit of about one lesion/10.sup.4 nucleotides to one lesion/10.sup.5 nucleotides.

Method to detect DNA damage and measure DNA repair rate


An apparatus for wastewater treatment is provided which can efficiently treat wastewater containing organic matter and, in addition, fluorine, with a relatively small number of tanks required for such treatment. The apparatus includes a first tank adapted to allow wastewater to flow thereinto, the first tank comprising an upper portion having a calcium carbonate mineral mass of smaller granule size and an aeration tube for fluidizing such calcium carbonate mineral mass while aerating the same in the wastewater, an intermediate portion and a lower portion which respectively include a calcium carbonate mineral mass of medium granule size and a calcium carbonate mineral mass of larger granule size, the medium and larger granule size masses of calcium carbonate mineral constituting immobilizing carriers for microbial propagation, and a circulation pump for transferring treated water resulting from treatment in the upper portion to the lower portion. In the upper portion, calcium carbonate mineral is fluidized by aeration so as to treat the wastewater through chemical reaction and, in the intermediate portion and lower portion, organic matter in the wastewater is biologically treated by microorganisms.

The present invention relates to a method and apparatus for wastewater treatment which can efficiently treat wastewater discharged from semiconductor and liquid crystal plants and the like that contains fluorine in addition to organic substances, such as surface active agents and organic solvents, with a relatively small number of tanks required for such treatment.
The present invention also relates to a method and apparatus for wastewater treatment which can efficiently treat wastewater that contains hydrogen peroxide in addition to organic substances, with a relatively small number of tanks.
From the view points of statutory laws and regulations for water pollution control, in the case where the wastewater contains, in addition to fluorine, organic substances, such as surfactant and organic solvents, it is necessary to treat the fluorine and also the organic substances to a predetermined concentration level. The presence of such organic matter in wastewater causes an increase in chemical oxygen demand (COD) and/or biochemical oxygen demand (BOD). Therefore, organic matter such as surface active agents in the wastewater must be positively removed despite the fact that they are chemically different from fluorine.
Hitherto, it has been usual practice that a mixed type of wastewater which contains, in addition to fluorine, organic substances, such as surfactant and organic solvents, is treated in such a way that the fluorine is first chemically treated by a chemical such as slaked lime in a tank and then, in a separate tank, organic matter, such as surfactant and organic solvents, are treated by employing a biological treatment method and/or a physical treatment method, such as activated carbon adsorption. This method for fluorine treatment using chemicals such as slaked lime and the like involves addition of chemicals in the process of treatment and, therefore, the resulting treated water has high electric conductivity. Therefore, such treated water has not been recycled for supply to ultrapure water production equipment.
As a typical example of conventional apparatus for removal of fluorine in wastewater there has been known one shown in FIG. 15. This apparatus for fluorine removal is such that fluorine-containing wastewater is fed into two separate calcium carbonate-packed tanks 533A and 533B for fluorine treatment therein (Japanese Patent Application Laid-Open No. 5-253576).
In this fluorine removal apparatus, fluorine-containing wastewater is fed into the calcium carbonate-packed tanks 533A and 533B for two-stage treatment, and outflow water is introduced into a circulation tank 542. The water under treatment in the circulation tank 542 is introduced into a membrane separation unit 543 in which the water is separated into condensed water containing calcium carbonate crystals flowed out of the second-stage calcium carbonate-packed tank 533B and membrane-permeated water. The condensed water is returned to the circulation tank 542. A part of the condensed water is returned to the first-stage calcium carbonate-packed tank 543A.
According to the arrangement of this fluorine removal apparatus, fluorine in the wastewater is immobilized to the calcium carbonate in the calcium carbonate-packed tanks 533A and 533B so that it is changed into calcium fluoride. After the lapse of a predetermined time period of treatment, such calcium fluoride is removed from the calcium carbonate-packed tanks 533A and 533B.
As another type of fluorine removal apparatus there has been known a calcium fluoride collecting apparatus as shown in FIG. 16 (Japanese Patent Application Laid-Open No. 5-254829). In this calcium fluoride collecting apparatus, a calcium carbonate reaction tank 644, or a reaction tank for reaction operation with respect to calcium fluoride, includes steam piping 647 which functions as a heating device, a blower 639 which functions as an air feeder device, and an aeration pipe 602. The calcium carbonate reaction tank 644 may include a vacuum deaerator (not shown).
Specifically, the calcium fluoride collecting apparatus incorporates a technique such that a supply of calcium carbonate from a calcium carbonate silo 646 is added to a fluorine-containing solution, the solution being then subjected to high temperature treatment at temperatures of 50 to 100.degree. C., hot air through-flow treatment, and/or hot vacuum deaeration treatment, whereby calcium fluoride is collected.
In the case where the object for treatment is organic matter-containing fluorine wastewater, such a fluorine removal apparatus as described above is incorporated, as shown by reference numeral 770 in FIG. 17, for example, into a wastewater treatment system 780 for treating organic matter-containing fluorine wastewater produced in a production room 731 of a semiconductor plant.
Generally, in a production room 731 of a semiconductor plant which fabricates integrated circuits (ICs) and the like, there is installed a so-called etching device 737 as shown in FIG. 17. The etching device 737 involves use of an etching agent composed principally of hydrogen fluoride and/or ammonium fluoride.
With recent microstructure oriented development in the manufacture of ICs, there has been a growing tendency toward the use of etchants with an organic substance, typically surfactant included therein. Therefore, etching device 737 discharges organic matter-containing fluorine wastewater into wastewater treatment system 780.
Separately from etching device 737, an organic solvent consuming unit 732 exists within production room 731. Organic solvent consumption unit 732 is an organic solvent user such that it cleans the surface of a wafer with an organic solvent and dries the same. Organic solvent consumption unit 732 discharges organic solvent-containing wastewater. This organic solvent-containing wastewater is also introduced into the wastewater treatment system 780 for treatment therein. That is, the organic solvent-containing wastewater discharged from the organic solvent consumption unit 732 is also directed through a pipe 726 to flow into a raw water tank 735.
Thus, the organic solvent-containing wastewater and the fluorine-containing wastewater, combined together into organic matter-containing fluorine wastewater, flow through pipe 726A for entry into raw water tank 735. Then, the wastewater is pumped by a raw water tank pump 736 to flow through pipe 726B for being introduced upward into a fluorine removal unit 770. A treating tank 733 of the fluorine removal unit 770 is packed with calcium carbonate mineral. In treating tank 733, therefore, fluorine in the wastewater reacts with the calcium carbonate mineral to form calcium fluoride. Therefore, by separating calcium fluoride from the wastewater it is possible to remove fluorine present in the wastewater.
Aforesaid fluorine removal unit 770 is almost incapable of removing organic matter, such as surfactant and organic solvents. The wastewater which has been treated in the fluorine removal unit 770 is caused to flow into a precipitation tank 713 through a pipe 727. The concentration of fluorine in the precipitation tank 713 is detected by a fluorine concentration meter 715. Organic matter concentration in the settling tank 713 is comparatively high. Therefore, the wastewater is introduced from the precipitation tank 713 into a typical biological treatment unit 740 for biological treatment of organic matter, such as surfactant and organic solvents.
In FIG. 17, acid type exhaust gases from the etching device 737 are treated by acid scrubber 734, while organic exhaust gases from organic solvent consumption device 732 are treated in activated carbon adsorption columns 738A, 738B.
Next, description is given of a conventional wastewater treatment apparatus for treating hydrogen peroxide wastewater from semiconductor and/or liquid crystal plants which contains organic matter, such as surface active agents and organic solvents.
In case where wastewater contains, in addition to hydrogen peroxide, organic substances, such as surfactant and organic solvent, both the hydrogen peroxide and the organic substances cause an increase in COD (chemical oxygen demand) in the wastewater. Therefore, it is necessary that hydrogen peroxide and organic matter, such as surfactant and organic solvent, in the wastewater must be surely removed. In the past, such organic matter-containing hydrogen peroxide wastewater has been treated in such a way that first, hydrogen peroxide is catalytically treated with activated carbon or the like and then organic matter, such as surfactant and organic solvent, are treated in a separate tank.
Hitherto, a hydrogen peroxide removal apparatus for removing hydrogen peroxide in wastewater of the type shown in FIG. 19 has been known wherein hydrogen peroxide is catalytically treated with granular activated carbon (Japanese Patent Application Laid-Open No. 6-91258). This hydrogen peroxide removal apparatus 870 includes a treating tank 833 comprising a catalytic zone 911 partitioned by a bottom wire mesh 905 and a peripheral wall 906 and open upward, and a sedimentation zone 912 surrounding the outer side of the catalytic zone 911 with the peripheral wall 906 placed therebetween. At lower peripheral locations there are provided an opening 904 which allows the sedimentation zone 912 to be kept in communication with the catalytic zone 911, and a feed port 903 for enabling wastewater to horizontally flow into the catalytic portion 911. In operation, granular activated carbon is previously placed into the catalytic zone 911 in a quantity range of 1 to 35% of the effective tank capacity of the catalytic zone 911.
In that condition, hydrogen peroxide-containing wastewater from a pipe 807A is introduced into the treating tank 833 through the feed port 903 at the tank bottom. The hydrogen peroxide-containing wastewater flows into the catalytic zone 911 through the wire mesh 905 to fill the catalytic zone 911. Meanwhile, from a branched pipe 807B and through the horizontal feed port 904 is introduced hydrogen peroxide-containing wastewater (the flow rate of which is adjustable by a valve 920) into the catalytic zone 911. As a consequence, within the catalytic zone 911 there occurs an eddy current along with an upward current so that the granular activated carbon comes in contact with the hydrogen peroxide-containing wastewater, whereby the hydrogen peroxide in the wastewater is decomposed into water and hydrogen by the catalytic action of the activated carbon. The wastewater which has undergone such treatment overflows the edge of the catalytic zone 911 into the sedimentation zone 912 and is discharged from a discharge port 918 provided behind a baffle plate 917 via a pipe 827. In this case, some part of the granular activated carbon may overflow along with post-treatment wastewater into the sedimentation zone 912, but the so overflown granular activated carbon is allowed to be detained and precipitated for a while, being then returned to the catalytic zone 911 through the opening 907. Therefore, only supernatant is discharged from a discharge port 918 of the sedimentation zone 912.
A hydrogen peroxide removal apparatus is often incorporated in a wastewater treatment system 1080, as illustrated in FIG. 18, for example, for treating organic matter-containing hydrogen peroxide wastewater generated at a production room 1031 of a semiconductor plant.
Generally, in a production room 1031 of a semiconductor plant which manufactures ICs (integrated circuits) and the like, a large number of manufacturing units are installed, including RCA cleaning unit 1037 which performs so-called RCA cleaning process, and organic solvent utilization unit 1032 for use of organic solvents, such as acetone and isopropyl alcohol. Aforesaid RCA cleaning process is a cleaning technique developed by RCA Consumer Electronics and typically comprises a first step of removing organic matter by using NH.sub.4 OH, HCl, and H.sub.2 O, and a second step of removing alkali metal and/or heavy metal by using HCl, H.sub.2 O.sub.2, and H.sub.2 O. With recent microstructure oriented development in the manufacture of ICs, there has been an increased tendency toward inclusion of surface active agents in above said NH.sub.4 OH and HCl. Organic matter-mixed wastewater from RCA cleaning unit 1037 or the like which contains hydrogen peroxide and organic substances, such as surfactant and organic solvent, flows through a pipe 1026 into a raw water tank 1035 in which the wastewater is adjusted in both quantity and quality to a certain measure.
On the other hand, organic matter-containing wastewater from the organic solvent utilization unit 1032 flows into the raw water tank 1035 through a pipe 1026A. Therefore, the hydrogen peroxide-containing wastewater and the organic matter-containing wastewater meet into a combined stream in the pipe 1026A so that they are present as organic matter-containing hydrogen peroxide wastewater in the raw water tank 1035.
Next, the wastewater is introduced by a raw water pump 1036 into a hydrogen peroxide removal unit 1070 via a pipe 1026B. Hydrogen peroxide in the wastewater is decomposed into oxygen and water within a tank 1033 of the hydrogen peroxide removal unit 1070. In this hydrogen peroxide removal unit 1070, however, it is almost impossible to remove organic matter, such as surfactant and organic solvent. As such, the wastewater which has undergone aforesaid treatment is introduced into the treating tank 1028 through a pipe 1027. The concentration of hydrogen peroxide in the treating tank 1028 is detected by a oxidation-reduction potentiometer 1034. In case that the wastewater in the treating tank has a high concentration of hydrogen peroxide, the wastewater is introduced into a biological treatment unit (not shown) for treatment of organic matter.
Meanwhile, as FIG. 18 shows, exhaust gas emitted from RCA cleaning unit 1037 and/or organic solvent utilization unit 1032 which contains organic substances (organic matter-containing exhaust gas) is treated by a treating system 1090 for organic matter-containing exhaust gas as provided separately from the treating system 1080 for organic matter-containing hydrogen peroxide wastewater.
Reference characters 1038A and 1038B designate activated carbon adsorption columns.
As earlier stated, at contemporary semiconductor plants where fabrication of ICs is becoming more and more microstructure-oriented, there is a growing tendency that organic matter such as surfactant and organic solvent get mixed in fluorine wastewater. The reason is that as ICs go more microstructural, greater need does exist for improvement of cleaning technique and, therefore, that it is a recent practice to mix organic matter, such as surface active agents, into cleaning agents and/or etching agents in order to obtain increased cleaning effect and/or etching effect.
Therefore, it is necessary that fluorine wastewater and organic matter-mixed wastewater containing surfactant, organic solvent, etc. must be treated in economical and rational way.
However, as already mentioned, in the past, fluorine and organic matter, such as surfactant in wastewater have been treated in separate tanks. More specifically, in the above described prior art treating arrangement, two separate apparatuses are required, namely, fluorine removal apparatus and biological treatment apparatus for treatment of organic matter. Where two different treatment tanks are separately installed, the problem is that high initial cost is required.
As FIG. 17 illustrates, at production room 731 of a semiconductor plant, etching unit 737 and other production units, and organic solvent utilization unit 732 are installed in large numbers. Along with recent trend that the fabrication of ICs is becoming more microstructure-oriented, it is now general practice that organic matter, such as surface active agent, is mixed into an etching agent which contains fluorine, and/or that chemicals containing an organic solvent are used in cleaning and drying operations. Therefore, in mixed types of wastewater which contain these chemicals (fluorine and organic substances, such as surfactant and organic solvents), organic substances present in wastewater are on the increase with time in quantity.
However, with prior art fluorine removal devices shown in FIGS. 15 and 16, and another prior art fluorine removal device 770 shown in FIG. 17, the problem is that such device, itself alone, is almost incapable of dealing with organic matter, such as surfactant and organic solvents.
The reason is that any of the prior art fluorine removal devices is unfit for microbial propagation and has no function to perform biological treatment, the device being operated in such a condition that no effect could be expected of the device for treatment of organic matter such as surfactant and organic solvents.
With reference to hydrogen peroxide wastewater, there is also a growing tendency that, at contemporary semiconductor plants, organic substances, such as surface active agents and organic solvents, mix into such wastewater. In view of the fact that microstructure-oriented IC production becomes more and more prominent, it is necessary to improve the cleaning technique accordingly. As such, there is a growing need for rational treatment of organic matter-mixed hydrogen peroxide wastewater of the kind generated at production room 1031 of a semiconductor plant as shown in FIG. 18, that is, hydrogen peroxide wastewater containing organic substances, such as surface active agents and organic solvents.
However, as already mentioned, it has hitherto been common practice that hydrogen peroxide is exclusively treated in one decomposition tank (hydrogen peroxide removal unit 1070) in which the hydrogen peroxide is catalytically decomposed with activated carbon into water and oxygen gas. Meanwhile, organic matter, such as surface active agent and organic solvent, are biologically treated alone, or subjected to physical adsorption treatment in an activated carbon adsorption column. Anyway, organic substances, such as surface active agent and organic solvent, in wastewater are treated separately from hydrogen peroxide. Therefore, two types of apparatuses are required, namely, apparatus for removal of hydrogen peroxide and apparatus for biological treatment of organic substances. This involves the problem of high initial cost.
As FIG. 18 illustrates, at production room 1031 of a semiconductor plant, there are present production related units including RCA cleaning unit 1037, and organic solvent utilization unit 1032 in large numbers. Further, for the convenience of productive operations, hydrogen peroxide and other chemicals containing organic matter, such as surfactant and organic solvent, are used for cleaning purposes. Therefore, production room 1031 generates wastewater of the sort in which hydrogen peroxide and organic matter, such as surfactant and organic solvent, are mixed together.
However, the above described conventional hydrogen peroxide removal unit 1070 involves the problem that it is almost incapable of independently performing the task of treating organic matter, such as surfactant and organic solvent. The reason is that the hydrogen peroxide removal unit 1070 does not permit propagation of microorganisms on the granular activated carbon because of the sterilizing action of hydrogen peroxide and, therefore, cannot be utilized for microbial treatment through propagation of microorganisms on the activated carbon.

Method and apparatus for wastewater treatment by chemical reaction of reactive filler and propagated microorganisms


A bearing arrangement includes a carrier device and a bearing socket for rotatably supporting a component. The bearing socket includes a sleeve fixed in a recess of the carrier device. A peripheral wall of the sleeve delimits an inner space for receiving a bearing journal of a component. The sleeve includes at least a first, inner catch element securing the bearing journal in the sleeve and a second, outer catch element securing the sleeve in the recess of the carrier device. The second catch element is formed from a catch tongue which is a portion of the peripheral wall of the sleeve and which has a hooked portion for engagement in a catch receiving member of the recess of the carrier device.

In practice, it is known to pivotably support components on a carrier device by means of a bearing socket. For example, in the case of folding roofs of cabriolet vehicles, it may be necessary to pivotably support a rigid rear window on a rear window connection rod of a roof rod assembly. In this instance, a rear window frame forms a carrier device in which an end-face bearing journal of the rear window connection rod rotatably or pivotably engages. For support, it is possible to use a flanged socket which is arranged in a recess of the rear window frame. The resulting bearing shaft may be secured by means of a securing plate or a screw. It is also known to clip-fit components in a blind hole. However, this involves the risk that the clip-fitting becomes disengaged in an undesirable manner as a result of any forces which may occur so that the bearing journal can be pulled out of the recess again. There is also the risk of the clip-fitting breaking.
In order to secure bearing locations, there is further known a securing clip, by means of which the rotatably supported component is secured in the bearing location.
It is further known to secure bearing locations by means of a rivet. However, this has the disadvantage that destruction-free disassembly is not possible.

Bearing arrangement having a bearing socket