bluuebunny/crossref_metadata_2025 huggingface dataset:
History of Perforated Duodenal and Gastric Ulcers
Authors: Lau W.Y. , Leow C.K.
Published: August 2002

Perforated peptic ulcer as a disease entity has been known since 167 bc. Surgical and nonsurgical treatment strategies for perforated peptic ulcer disease were not developed until the latter half of the nineteenth century. The history of the gradual evolution of the various forms of treatment adopted for the conditions over the last century and a half is described.
Is Percutaneous Cholecystostomy the Optimal Treatment for Acute Cholecystitis in the Very Elderly?
Authors: Sugiyama Masanori , Tokuhara Makoto , Atomi Yutaka
Published: August 2002

In elderly patients emergent cholecystectomy for acute cholecystitis is a high risk procedure. We prospectively assessed the value of percutaneous cholecystostomy for acute cholecystitis in 38 consecutive elderly (≥ 80 years) patients. All 38 underwent percutaneous transhepatic cholecystostomy under ultrasonographic and fluoroscopic guidance for acute cholecystitis (25 calculous, 13 acalculous). Eight (21%) patients had acute severe medical problems, such as shock and respiratory distress. Thirty‐one (82%) patients had chronic severe underlying diseases, including cardiovascular and neurologic diseases. Cholecystostomy was successful in all 38 patients. Prompt clinical improvement was obtained in 36 (95%) patients. Morbidity and mortality rates were 3% and 3%, respectively. After cholecystostomy, 10 patients with cholelithiasis underwent elective cholecystectomy without serious complications. Two patients underwent percutaneous cholecystolithotomy, which produced complete resolution of symptoms. Four of 12 patients with and none of 12 without cholelithiasis had recurrent cholecystitis after catheter removal during a mean follow‐up of 1.8 years. A second cholecystostomy was successful in these four patients. Elderly patients are often poor surgical candidates because of severe cholecystitis or concomitant medical problems. Percutaneous cholecystostomy is a safe, effective treatment for acute cholecystitis even in elderly patients. For calculous cholecystitis, cholecystostomy can be followed by elective surgery, if possible, or by nonsurgical treatment or expectant conservative management in high‐risk patients. Cholecystostomy may be a definitive treatment for acalculous cholecystitis.
Expression of Inducible Nitric Oxide Synthase in Circulating Neutrophils of the Systemic Inflammatory Response Syndrome and Septic Patients
Authors: Tsukahara Yasuhiro , Morisaki Takashi , Horita Yoshiyuki , Torisu Motomichi , Tanaka Masao
Published: August 2002

There is increasing evidence that nitric oxide (NO) is an important factor in the pathogenesis of septic shock. It is known that polymorphonuclear neutrophils (PMNs) are activated during sepsis or after surgical stress, and they then release various toxic mediators including free radicals. It has not been clear whether NO synthesis can be induced in circulating PMNs. Blood samples were obtained from 11 patients with sepsis, 23 patients with systemic inflammatory response syndrome (SIRS), and 16 patients without SIRS (nonSIRS) who underwent operation. We examined mRNA expression of inducible NO synthase (iNOS) in circulating PMNs from those patients pre‐ and postoperatively using the reverse transcriptase polymerase chain reaction (RT‐PCR) method and measured their serum nitrate (NO2\‐) + nitrate (NO3\‐) concentration, peripheral blood white blood cell (WBC) count, and serum C‐reactive protein (CRP) level. The frequency of iNOS expression in PMNs increased in sepsis (100%) and SIRS (70%) patients compared to that in nonSIRS patients (18%) (p < 0.001). The peripheral WBC count and CRP level were significantly higher in iNOS‐positive patients than in iNOS‐negative patients (p < 0.05 andp < 0.01, respectively). Postoperatively, the serum NO2\‐+ NO3\‐ concentration increased in 87% of septic patients and in 56% of patients with SIRS (p < 0.05 for both). Our study indicated that iNOS mRNA expression is induced in human circulating PMNs of patients with postoperative sepsis and SIRS and may be involved in the pathogenesis of the sepsis syndrome.
Current Status of Indications for Surgery in Peptic Ulcer Disease
Authors: Jamieson Glyn G.
Published: August 2002

The eradication of Helicobacter pylori in patients with peptic ulcer disease has greatly diminished the need for antiulcer surgery. However, in societies where such drug therapy is considered too expensive and because occasional patients remain refractory to optimal medical therapy, elective surgery for duodenal ulcer disease is still carried out. If the required expertise is available, it can be undertaken laparoscopically. The advent of endoscopic therapies such as heater probe therapy and injection sclerotherapy has also greatly diminished the need for emergency surgery in bleeding peptic ulcer disease. Once again, however, when such therapy fails surgery is still indicated. Even with perforated peptic ulcer disease the role of surgery has receded somewhat, but here not because of changes in drug therapy. Nonoperative management of perforation is indicated in fit patients if the diagnosis is in doubt, in any patient when surgical facilities are unavailable (e.g., remote geographic areas, on board ship), or when a patient is extremely ill either because of co‐morbidity or late presentation of the disease. Operation should be considered in all patients when the perforation is established to be unsealed, particularly after a trial of conservative management, and in all patients who are otherwise fit.
Wound Healing Associated with Severe Surgical Illness
Authors: Clark Matthew A. , Plank Lindsay D. , Hill Graham L.
Published: August 2002

Severe injury or infection is associated with a hypermetabolic response that, when excessive, results in impaired wound healing and as a consequence increased morbidity and mortality. The objective examination of wound healing in humans is difficult and generally requires the use of models. Evidence is accumulating that nutritional and growth factors play important roles in improving the wound healing response, particularly after thermal injury and uncomplicated major surgery. The septic patient represents the biggest challenge to those seeking to optimize wound healing capacity. Advances in molecular biology have provided promising therapies in experimental studies of wound healing that await clinical investigation.
Current status of the threatened amphibians and reptiles of Japan
Authors: Ota H.
Published: August 2002

This article compares amphibian and reptile components of the original and revised versions of the Red List of Japan, and analyzes geographic patterns of, and major threats to, species and subspecies now assigned to the threatened categories. The numbers of both amphibians and reptiles categorized as threatened in the Red List of Japan have increased greatly through its revision as a result of recent progress in the taxonomy of these groups in Japan, the introduction of new criteria for risk assessment, and unexpectedly rapid declines in the status of several taxa. Threatened taxa of amphibians and reptiles in the revised list tend to be concentrated in the Ryukyu Archipelago, where deforestation seems to be the major ultimate cause of declines. Reduction in the quality and quantity of inland water environments seems to be the major cause of declines in several endemic amphibians from the main islands of Japan. The importance of conservation was emphasized in the revised list by progress in taxonomy, by new insights and data on the estimation of temporal dynamics of population density or habitat size for threatened taxa, and by the impacts of and need to prevent further deforestation in the Ryukyus and of the ongoing destruction of inland water habitats on the main islands of Japan.
Comparison of Skin Staples With Sutures for Anastomosis of the Small Intestine in Dogs
Authors: Coolman Bradley R. , Ehrhart Nicole , Pijanowski Gerald , Ehrhart E.J. , Coolman Shindok L.
Published: August 2002

Objectives—To develop a technique for approximation of end‐to‐end intestinal anastomoses by using a disposable skin stapler and to compare the stapling technique with an interrupted hand‐sewn approximating end‐to‐end anastomosis of the canine jejunum.

Study Design—In vitro evaluation of the stapling technique, followed by an in vivo study of healing and clinical response in dogs.

Animal Population—18 mixed‐breed adult dogs.

Methods—The anastomotic technique was developed and tested in fresh canine jejunum. Fourteen stapled approximating anastomoses (SAA) and 14 hand‐sewn approximating anastomoses (HAA) were performed in 6 cadavers under simulated surgical conditions. Anastomotic construction times, initial bursting strengths, initial lumen diameters, and gross appearance of the 2 techniques were compared. Healing and clinical response were evaluated in 12 purpose‐bred dogs assigned to 2 groups of 6 animals each. Each dog had 1 SAA and 1 HAA performed in the jejunum, 50 cm apart. Six dogs were killed on postoperative day 4, and 6 dogs were killed on postoperative day 21. Anastomotic construction time, gross and histological healing, bursting strength, lumen diameter, and circumference were compared between techniques.

Results—Mean construction time for SAA was significantly faster than for HAA (P= .0001). None of the anastomoses leaked, and there were no major clinical complications in any dog. Bursting strengths were not significantly different at any time for the 2 techniques. Initial bursting strength was 31% to 35% of the normal jejunum. A nonsignificant decrease in bursting strength was observed by postoperative day 4 (26% to 28% of normal), and a significant increase in bursting strength was observed by postoperative day 21 (100% to109% of normal). Neither technique decreased the initial lumen diameter. However, both techniques resulted in a similar degree of luminal stenosis as the anastomoses healed. Anastomotic lumen diameter was significantly decreased from normal in both groups at day 4 (86% to 88% of normal) and day 21 (90% to 91% of normal). There was no significant difference between the circumference of the anastomoses and normal jejunum at any time. Histological analysis showed similar healing for the hand‐sewn and stapled techniques at 4 and 21 days after surgery. For both surgical techniques, day 21 anastomoses had significantly less inflammation and necrosis, significantly more fibrosis, and significantly better continuity of histological layers when compared with day 4 anastomoses.

Conclusion—Approximating end‐to‐end intestinal anastomosis with a skin stapler is equivalent in bursting strength, lumen diameter, lumen circumference, and healing characteristics to the traditional hand‐sewn technique, but it can be performed in significantly less time.

Clinical Relevance—Skin stapling devices can be used to create technically simple, rapid, and safe end‐to‐end anastomoses in canine jejunum.
Clinical Experiences With Axial Deviation of the Aryepiglottic Folds in 52 Racehorses
Authors: King Dana S. , Tulleners Eric , Martin Benson B. , Parente Eric J. , Boston Ray
Published: August 2002

Objective—To describe the clinical findings in 52 racehorses with axial deviation of the aryepiglottic folds (ADAF) and to report outcome in 33 of these horses after either rest or transendoscopic laser excision of aryepiglottic fold tissue.

Study Design—Retrospective study.

Animal or Sample Population—Racehorses admitted for high‐speed treadmill (HST) evaluation of poor performance.

Methods—Medical records and videotapes of resting and exercising videoendoscopic examinations were reviewed. Racing performance records and owner or trainer interviews, at least 1 year after HST examination, were used to compare results after either surgical management or rest in 33 horses with ADAF and no other upper‐airway abnormalities.

Results—ADAF occurred in 6% of horses evaluated for poor performance. No breed or gender predisposition existed, but horses with ADAF were younger than the overall population evaluated on the HST. Of 52 horses with ADAF, 19 horses had at least one other upper‐airway abnormality. There was no apparent association between ADAF and other causes of dynamic upper‐respiratory obstruction. Surgical correction was successfully performed in standing or anesthetized horses without complications. When ADAF was the only upper‐airway obstruction, 75% of horses that had surgery and 50% of rested horses had objective improvement in performance. Owners and trainers also perceived greater improvement in performance in horses that had surgery.

Conclusions—Whereas surgical management of ADAF is recommended, clinical experience indicated that it is not required to resolve ADAF in all horses. However, owners and trainers of horses that had surgery were more satisfied with outcome than those with horses managed conservatively.

Clinical Relevance—Diagnosis of ADAF can only be made by videoendoscopic evaluation during high‐speed exercise. Transendoscopic laser excision of the collapsing portion of the aryepiglottic folds can be performed safely in standing horses and results in resolution of airway obstruction and rapid return to training.
Mutational Analysis of the Three Conserved Valine Residues of Insulin and a Proposal of “Isosteric Residue”
Authors: Guo Zhan‐Yun , Tang Yue‐Hua , Zhang Zhou , Feng You‐Min
Published: August 2002

To further understand the role of the three conserved Val residues in insulin, B12Val, B18Val, and A3Val, five insulin mutants‐‐[A3Ser]insulin, [B12Thr]insulin, (desB30)[B12Ser]insulin, [B18Thr] insulin, and [B18Leu]insulin‐‐were obtained by means of site‐directed mutagenesis and their receptor‐binding activities as well as in vivo biological potencies were measured. The two B18 mutants, [B18Thr]insulin and [B18Leu]insulin, both retained relatively high receptor‐binding activities (70% and 30% of native porcine insulin, respectively) as well as relatively high in vivo biological potencies. The receptor‐binding activities of [B12Thr]insulin and (desB30)[B12Ser]insulin were 5.1% and 0.2%, respectively. However the in vivo biological potency of [B12Thr]insulin was still about 50% of native insulin, whereas that of (desB30)[B12Ser]insulin decreased drastically. The [A3Ser]insulin retained 1.4% of the receptor‐binding activity and low in vivo biological potency. These results, together with previous reports showed that when the three conserved Val residues were replaced by residues containing a β‐branched side‐chain, such as Thr or Ile, the insulin mutants retained higher biological activities than those mutants replaced by other residues. Here we propose that Val, Thr, and Ile are “isosteric residues” because they all contain a β‐branched side‐chain. This proposal may have perhaps general significance in protein design and protein engineering.
Polyimide Foams for Aerospace Vehicles
Authors: Weiser Erik S , Johnson Theodore F , St Clair Terry L , Echigo Yoshiaki , Kaneshiro Hisayasu , Grimsley Brian W
Published: August 2002

Due to a demand by the aerospace industry, NASA has begun developing the next generation of polyimide foams which could be utilized to reduce vehicle weight for the X-33 and Reusable Launch Vehicle (RLV) programmes. The activity at NASA Langley Research Center focuses on developing polyimide foam and foam structures which are made using monomeric solutions or salt solutions formed from the reaction of a dianhydride and diamine dissolved in a mixture of foaming agents and alkyl alcohols. This process can produce polyimide foams with varying properties from a large number of monomers and monomer blends. The specific densities of these foams can range from 0.008 g cc−1 to 0.32 g cc−1.

Polyimide foams at densities of 0.032 g cc−1 and 0.08 g cc−1 were tested for a wide range of physical properties. The foams demonstrated excellent thermal stability at 321°C, a good thermal conductivity at 25°C of 0.03 W m−1 K−1, compressive strengths as high as 0.84 MPa at 10% deflection and a limiting oxygen index of 51%. Thermomechanical cyclic testing was also performed on these materials for 50 cycles at temperatures from −253°C to 204°C. The foams survived the cyclic testing without debonding or cracking. Thermal forming of the 0.032 g cc−1 foam was performed and a minimum radius curvature of 0.0711 m was achieved. The foams exhibited excellent properties overall and are shown to be viable for use as cryogenic insulation on the next generation RLV.
Excitonic Interactions in Covalently Linked Porphyrin Dimers with Rotational Freedom
Authors: STOMPHORST REGIEN G. , KOEHORST ROB B. M. , ZWAN GERT VAN DER , BENTHEM BERT , SCHAAFSMA TJEERD J.
Published: August 2002

Experimental and calculated absorption spectra are compared for four different porphyrin dimers covalently linked by alkyl- or phenyl bridges. The spectra of the corresponding monomers were used as a reference to determine the experimental exciton,ic shift(s) of the absorption spectrum in the Soret region. The excitonic interaction was calculated using the point dipole approximation and taking into account the restricted conformational freedom of the monomeric units in the dimers due to steric constraints. The constraints were independently verified by magnetic dipole-dipole broadening of the EPR spectra of several ( CuTPP )2-substituted dimers. The observed and calculated absorption spectra agree at least semiquantitatively.
Layoffs and violence revisited
Authors: Catalano Ralph , Novaco Raymond W. , McConnell William
Published: August 2002

Extension of frustration‐aggression theory suggests both the “provocation hypothesis” (laid‐off workers are at elevated risk of psychogenic violence) and the “inhibition hypothesis” (workers who fear job loss will be at reduced risk of such violence). Previous research found that both hypotheses were supported with data indexing layoffs and the incidence of civil commitment for danger to others in San Francisco County, California, for the 52 weeks beginning August 1, 1993. Whether those results generalize to other times and places has not been determined. We elaborated the theory and replicated the test in San Francisco for the 149 weeks beginning August 1, 1994, and ending June 7, 1997. We also replicated the test using data from Allegheny County, Pennsylvania, for the 111 weeks beginning January 1, 1996, and ending February 28, 1998. The original results from San Francisco County are replicated for men in both communities. The results for women are replicated for the new and more extended period in San Francisco County but not in Allegheny County. Scientific and social policy reasons for continued study of economic conditions on aggressive behavior are discussed.Aggr. Behav. 28:233–247, 2002. © 2002 Wiley‐Liss, Inc.
Achieving voice and security in colleges of education
Authors: Day Michael J. , Amstutz Donna D. , Whitson Donna L.
Published: August 2002

Finding a niche in teacher education programs in colleges of education can help adult educators secure their place in higher education while still maintaining integrity within the discipline.
Nurturing intuition through group learning
Authors: Weinberg Zelman Annette
Published: August 2002

The collaborative inquiry group on intuition met in a college setting to discuss what participants had acknowledged internally but not discussed openly. They validated intuition as a way of knowing and learned how to nurture it in themselves and others.
Municipal firefighter exposure groups, time spent at fires and use of self‐contained‐breathing‐apparatus
Authors: Austin C.C. , Dussault G. , Ecobichon D.J.
Published: August 2002

Background

Previous studies have found significant associations between firefighting and cancer.

Methods

Fires, vehicle movement, and firefighter job assignment were determined, and storage and distribution of self‐contained‐breathing‐apparatus (SCBAs) were tracked for 12 months. Time spent at fires and use of SCBAs were calculated.

Results

Only 66% of fire department personnel were 1st‐line combat firefighters. Number of runs was an unreliable surrogate for time spent at fires. Eight firefighter exposure groups were identified (based on job title, firehall assignment, and time spent at fires), ranging from no exposures to 3,244 min/year/firefighter. SCBAs appear to have been used for approximately 50% of the time at structural fires but for only 6% of the time at all fires.

Conclusions

Failure of previous studies to identify homogeneous exposure groups may have resulted in misclassification and underestimates of health risks. The approach used in this study may be used in epidemiological studies to identify exposure/response relationships. Am. J. Ind. Med. 40:683–692, 2001. © 2001 Wiley‐Liss, Inc
Significance of a prenatally diagnosed del(10)(q23)
Authors: Zaslav A.L. , Fox J.E. , Jacob J. , Kazi R. , Allan S. , Shklooskaya T. , Sohal D. , Kleyman S.M. , Verma R.S.
Published: August 2002

Structural chromosome mosaicism is rare. We report a case of prenatal mosaicism for a deletion of chromosome 10(q23). To our knowledge, there are only three reports of prenatally diagnosed cases of del(10)(q23). Two of these cases were due to an inherited fragile site. In the present case amniocentesis revealed 46,XY,del(10)(q23)[9]/46,XY[45]. Follow‐up chromosome analysis of peripheral blood and placental tissue from a phenotypically normal liveborn male revealed the del(10)(q23) in only 3/100 blood cells grown in low‐folate medium. It appears that prenatally diagnosed deleted (10q) mosaicism represents culture artifact and is not clinically significant. © 2002 Wiley‐Liss, Inc.
Clinical variability in mucolipidosis III (pseudo‐Hurler polydystrophy)
Authors: Tylki‐Szymańska Anna , Czartoryska Barbara , Groener Johanna E.M. , Ługowska Agnieszka
Published: August 2002

Mucolipidosis III (MLIII) is caused by a deficiency of UDP‐N‐acetylglucosamine:lysosomal enzyme N‐acetylglucosamine 1‐phosphotransferase (phosphotransferase) activity, an enzyme responsible for the formation of the recognition marker on most lysosomal enzymes. The consequences of this defect are impairment of many lysosomal catabolic processes. A deficiency of phosphotransferase activity causes two phenotypically different diseases: mucolipidosis II and a rare form, mucolipidosis III (pseudo‐Hurler polydystrophy). The purpose of this article is to report three patients with ML III, presenting quite different clinical courses: Patient 1 is a 13‐year‐old girl in whom the only symptoms of ML III were joint stiffness of the hands. Patients 2 and 3 are sibs: a 5‐year‐old boy with a severe form of ML III and his 2‐year‐old sister, who is less affected than her brother at the same age. A comparison of biochemical results and the clinical picture of our patients with cases in the literature is presented. © 2002 Wiley‐Liss, Inc.
Synthesis of a star‐shaped poly(ethylene‐co‐propylene) copolymer as a viscosity index improver for lubricants
Authors: Liou I‐Chun , Tsiang Raymond Chien‐Chao , Wu James , Liou Jin‐Shang , Sheu Hun‐Chang
Published: August 2002

A saturated star‐shaped poly(ethylene‐co‐propylene) copolymer, (EP)star, has been synthesized for use as a viscosity index improver in lubricants. Polyisoprene arms were first anionically synthesized using n‐butyllithium as the initiator, followed by a linking reaction with divinylbenzene at the optimum temperature of 60°C. The resulting star‐shaped polyisoprene, (I)star, was then hydrogenated to eliminate the double bonds of the polyisoprene forming the poly(ethylene‐co‐propylene) structure. The degree of branching (number of arms on each molecule) increases with increase in the mole ratio of divinylbenzene to n‐butyllithium. Increasing the arm length adversely affects the linking efficiency and a minimum amount of tetrahydrofuran (THF) at a THF:n‐butyllithium molar ratio of 1.12 was needed in order to achieve a maximum linking efficiency of approximately 85%. The Tg of poly(ethylene‐co‐propylene) is about 10°C higher than that of the original polyisoprene. Compared with (I)star, (EP)star has a thermal decomposition temperature that is 50°C higher but is independent of the arm length or the degree of branching. Viscosity measurement results for (EP)star reveal that intrinsic viscosity depends only on the arm length but not the degree of branching. Adding 1 wt % of (EP)star markedly increases the viscosity index of a LN base oil. The addition of 1 wt % of (EP)star increases the viscosity index (95 for base oil) up to a number between 111 and 145, with the exact number depending upon its arm length and degree of branching. With a fixed arm length, an (EP)star having a higher degree of branching increases the viscosity index more than one having a lower degree of branching. On the other hand, the viscosity index increases with increase in the arm length when the degree of branching is fixed. Adding 1 wt % of (EP)star also causes a change in the pour point of the lubricant with the pour point decreasing with increase in the degree of branching. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1911–1918, 2002
Different parameters controlling the initial solubility of two thermoplastics in epoxy reactive solvents
Authors: Bonnaud L. , Bonnet A. , Pascault J. P. , Sautereau H. , Riccardi C. C.
Published: August 2002

The influence of different factors on the miscibility of diglycidyl ether of bisphenol A (DGEBA)/thermoplastic blends was studied. DGEBA/poly(ether imide) (PEI) blends exhibited upper critical solution temperature behavior. The addition of a trifunctional epoxy [triglycidyl para‐amino phenol (TGpAP)] increased the miscibility window. The addition of diamines as hardeners could also increase [4,4′‐methylene‐bis(3‐chloro‐2,6‐diethylaniline) (MCDEA)] or decrease (4,4′‐diaminodiphenylsulfone) the miscibility window. DGEBA/poly(ether sulfone) (PES) blends showed lower critical solution temperature behavior. The addition of TGpAP had an effect similar to that for PEI blends, but the presence of MCDEA as a hardener decreased the miscibility of epoxy/PES blends. The modeling of the cloud‐point curves was performed with the Flory–Huggins equation (Flory, P. J. Principles of Polymer Chemistry; Cornell University Press: Ithaca, NY, 1953; p 672) according to the procedure developed by K. Kamide, S. Matsuada, and H. Shirataki (Eur Polym J 1990, 26, 379), with the interaction parameter used as the fitting parameter. A phenomenological model that takes into account the molar mass of DGEBA and the amount of TGpAP is proposed and is found to predict the cloud‐point temperature of any TGpAP/DGEBA/PEI blend. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1385–1396, 2002
Mechanical and dynamic mechanical properties of rice husk ash–filled natural rubber compounds
Authors: Da Costa H. M. , Visconte L. L. Y. , Nunes R. C. R. , Furtado C. R. G.
Published: August 2002

A laboratory‐sized two‐roll mill was used to incorporate rice husk ash into natural rubber (NR). A conventional vulcanization system was used for curing and cure studies were carried out on a Monsanto rheometer. Physical testing of the NR vulcanizates involved determining tensile and tear resistances and hardness. Swelling behavior of NR compounds and scanning electron microscopy were used to investigate the interaction between rice husk ash and natural rubber. Also, dynamical mechanical thermal analysis was used to assess filler–rubber interactions in terms of storage modulus (E′) and loss tangent (tan δ). For comparison purposes, two commercial fillers, precipitated silica (Zeosil‐175) and carbon black (N774), were also used. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2331–2346, 2002
Novel dibutyltin oxide‐tributyl phosphate condensate as accelerator for the curing of the epoxy resin/4,4′‐diamino diphenyl sulfone system. II. Toughening of the resin with hydroxyl‐terminated poly(tetramethylene) glycols
Authors: Wu Qi , Xu Jianjun , Yu Yunzhao
Published: August 2002

When a crystalline Bu2SnO‐Bu3PO4 condensate was used as a catalyst for the curing of the Epon 828/DDS system, the addition of hydroxyl group to epoxy group took place. On the basis of this reaction, direct employment of poly(tetramethylene) glycols (PTMG) as toughener for the epoxy resin system was successful. Morphology of the modified resin depended on the molecular weight and the concentration of PTMG. With the incorporation of a small amount of PTMG, the critical fracture energy of the cured resin was improved greatly, while the flexural strength and the modulus were less influenced. A slight enhancement in glass transition temperature (Tg) of the modified resin was found up to the PTMG concentration of 5 phr; further increase of the PTMG concentration caused a significant lowering of Tg. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1237–1242, 2001
Effect of polymer compositions on the fabrication of poly(ortho‐ester) microspheres for controlled release of protein
Authors: Bai Xin‐Lai , Yang Yi‐Yan , Chung Tai‐Shung , Ng Steve , Heller Jorge
Published: August 2002

Eight kinds of self‐catalyzed poly(ortho‐esters) (POEs) are used to fabricate bovine serum albumin (BSA)‐containing microspheres using a W/O/W double‐emulsion solvent extraction/evaporation method. All eight kinds of POE polymers used in this study are shown able to form microspheres under proposed fabrication conditions. The surface morphology and inner structure of the microspheres are analyzed using scanning electron microscopy (SEM). The microspheres have a size range from 64.7 to 120.2 μm. POE with a higher viscosity leads to bigger microspheres. It was found that the POE composition has a significant effect on BSA release profiles. POEs, which are more hydrophilic and contain a greater amount of glycolide or lactate (latent acid), yield higher BSA release rates. Specifically, POE containing 1,6‐hexanediol diglycolide (HD‐diGL) microspheres have the highest BSA release rate after a 20‐day test through a combination of surface erosion and diffusion mechanisms. POE containing a high percentage of the trans‐cyclohexanedimethanol (CDM) segment tends to yield microspheres with a lower release rate because of its hydrophobic nature. It was also found that the BSA release rate is more rapid at 37°C than at 22°C because of faster polymer degradation and water penetration at 37°C. Experimental results suggest that various protein release rates can be achieved by using different compositions of POEs. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1630–1642, 2001
Characterization of structure of comblike polymer by pyrolysis gas chromatography and Fourier transform infrared spectroscopy
Authors: Yang Rui , Li Guoping , Wang Kunhua
Published: August 2002

The characterization of branching in comblike polymers using high‐resolution pyrolysis gas chromatography (HRPGC) and Fourier transform infrared spectroscopy (FTIR) is investigated. The branching type can be identified from characteristic peaks of monomer and a group of dimers in pyrograms derived from α‐ and β‐scission of branched atoms. By resolving the overlapping bands between 2800–3000 cm−1, the relative absorbance of CH2 can be used to calculate the average branch length L. This method is helpful in evaluating the property of drag‐reduction agents. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 359–363, 2001
Creep enhanced adsorbtion of water or aqueous zinc chloride solution increases the creep rate of nylon 6,6
Authors: Nair S. V. , Donovan J. A.
Published: August 2002

The creep behavior of nylon 6,6 at 21°C was significantly altered when the local “dry” environment was changed to water mist or an aqueous zinc chloride mist. Nylon 6,6 was found to exhibit logarithmic creep because the relation between the log of the strain rate and the creep strain was linear with a negative slope. The effect of changing the creep environment from dry to wet, with the addition of moisture from an ultrasonic humidifier was to decrease the negative slope by 50–70% within 5–10 min. This effect could be interpreted as a decrease in modulus, which allowed for easier creep deformation. Based on the stress‐free diffusivity of water in nylon and the dimensions of the test sample the time to saturate the sample was estimated to be about 100 h. Therefore, there appeared to be synergism between the creep deformation and the environment that dramatically enhanced the rate of saturation and slowed the decrease in the creep rate. The tentative explanation provided is that the aqueous solutions, by binding to the hydrogen bonds in nylon, are dragged into the sample during creep deformation, and the dragged‐in aqueous solution then plasticizes nylon. This is analogous to the conclusion in another recent study that showed that deformation, during a hardness test, in the presence of aqueous zinc chloride, transported the solution species deeper into the sample than could be reasonably explained by ordinary diffusion processes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 494–497, 2001
Modeling of particle growth and morphology in the gas phase polymerization of butadiene. I. Model and its solution method
Authors: Zhao Junzi , Sun Jianzhong , Zhou Qiyun , Pan Zuren
Published: August 2002

An improved multigrain model designed to simulate the polymeric particle growth and morphology in the gas phase polymerization of butadiene was developed. In the model, the effects of intraparticle heat and mass transfers, heat and mass transfer resistances at the particle boundary layer, sorption of 1,3‐butadiene in 1,4‐cis‐polybutadiene, and intrinsic kinetics on the polymeric particle growth and morphology were considered. An improved numerical method was also proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 719–729, 2001
Three‐site mechanism and molecular weight: Time dependency in liquid propylene batch polymerization using a MgCl2‐supported Ziegler‐Natta catalyst
Authors: Shimizu Fumihiko , Pater Jochem T. M. , Weickert Günter
Published: August 2002

This article demonstrates that the molecular weight of propylene homopolymer decreases with time, and that the molecular weight distribution (MWD) narrows when a highly active MgCl2‐supported catalyst is used in a liquid pool polymerization at constant H2 concentration and temperature. To track the change in molecular weight and its distribution during polymerization, small portions of homo polymer samples were taken during the reaction. These samples were analyzed by Cross Fractionation Chromatograph (CFC), and the resulting data were treated with a three‐site model. These analyses clearly showed that the high molecular weight fraction of the distribution decreases as a function of time. At the same time, the MWD narrows because the weight‐average molecular weight decreases faster than the number‐average molecular weight. A probable mechanism based on the reaction of an external donor with AlEt3 is proposed to explain these phenomena. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1035–1047, 2001
Silane‐modified PVC pervaporation membranes for bromoform/water separation
Authors: Sluszny Ariel , Silverstein Michael S. , Narkis Nava , Narkis Moshe
Published: August 2002

The transport properties of a unique family of silane‐modified poly(vinyl chloride) (PVC) pervaporation membranes for the separation of halogenated hydrocarbons from water were investigated. The PVC was modified by using a vinyl silane to improve its resistance to attack by halogenated hydrocarbons and to increase the flux. Two preparation routes were used: Route i included an initiator to promote the vinyl reaction before the hydrolysis and condensation of the methoxy silane group, whereas Route ni did not. The structures of the membranes were characterized and related to the transport properties, as derived from batch pervaporation experiments. The permeability of unmodified PVC membranes increases with exposure to haloorganics at low concentrations. Initially, the modified membranes exhibited a higher permeability than PVC and a lower selectivity. At long pervaporation times, the silane‐modified membranes exhibited a higher selectivity than PVC. The different preparation routes led to different morphologies, which affected the performance of the membranes; Route ni membranes exhibited higher permeabilities and selectivity than Route i membranes. Rubbery polydimethylsiloxane membranes were resistant to haloorganics but their high water permeability and low selectivity make them unsuitable for this pervaporative separation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1429–1438, 2001
Influence of cure treatment on extent of reaction and glassy modulus for BADGE‐DDM epoxy resin
Authors: Ellis B. , Found M. S. , Bell J. R.
Published: August 2002

The extent of conversion of epoxy groups cured with diaminodiphenyl methane, a diamine, at 100°C was approximately 100%, and the glass‐transition temperature (T) was found to be an increasing function of cure time with very large increases with extended postcure treatments at 180°C. However, this considerable increase in the Tg with postcure at 180°C was not due to the reactions of epoxy and amine groups. The specific volume reduced with the Tg to a minimum at 103° for the cured samples but showed a very slight increase with the Tg for the postcured samples. It was also found that the glassy modulus (Eg) was a linear decreasing function of the Tg. There were two separate relationships between the Eg and the rubbery modulus that depended on the cure conditions and suggested that the “structure” formed due to cure at a temperature of 100°C was different than that at postcure, which was 180°C. The most sensitive structural parameter for these cured epoxy resins was their T. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1265–1276, 2001
Immobilization of lipase on poly(N‐vinyl‐2‐pyrrolidone‐co‐styrene) hydrogel
Authors: Basri M. , Harun A. , Ahmad M. B. , Razak C. N. A. , Salleh A. B.
Published: August 2002

Lipase from Candida rugosa was immobilized by entrapment while polymerizing a poly(N‐vinyl‐2‐pyrrolidone‐co‐styrene) [poly(VP‐co‐ST)] hydrogel using ethylene dimethacrylate (EDMA) as the crosslinking agent. The immobilized enzymes were used in the esterification reaction of oleic acid and butanol in hexane. The activities of the immobilized enzymes and the leaching ability of the enzyme from the support with respect to the different compositions of the hydrogels were investigated. The thermal, solvent, and storage stability of the immobilized lipases were also determined. The activities were relatively higher when the percent compositions of VP(%):ST(%) were 50:50 and 30:70. The lipase immobilized on VP(%):ST(%) 50:50 showed the highest thermal stability, while lipase immobilized on VP(%):ST(%) 30:70 exhibited the highest solvent stability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1404–1409, 2001
Three‐group type mechanism in the curing behavior of polyacrylate and blocked toluene diisocyanate
Authors: Xiao Dequan , Chen Deben , Zhou Zonghua , Zhong Anyong
Published: August 2002

Abstract:

The curing behavior of two resins, five blocked toluene diisocyanate (TDI) crosslinkers and polyacrylate, was studied using Torsional Braid Analysis (TBA) to examine their dynamic mechanical properties. The curing process was clearly divided into two stages. Associated with data from in situ FTIR at the molecular level, the first stage was the reaction of deblocked NCO and hydroxyl in polyacrylate. In the second stage, the deblocked NCO attacked the hydrogen in NH group of the urethane bond to conduct deep curing. Computer modeling was used to investigate the lowest‐energy configuration of the crosslinker molecule. The space hindrance effect in the molecule causes this type of three‐group crosslinking curing mechanism in the blocked TDI crosslinker. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 83: 112–120, 2002
Physical properties of twisted structures. II. Industrial yarns, cords, and ropes
Authors: Pan Ning , Brookstein David
Published: August 2002

In this article, we review the progress made in the area of industrial twisted fibrous structures. First, we focus on the general geometrical description of the structures, and then move to issues including the tensile behavior and fracture process. The effects of fiber bending and torsion, strain rate, and viscoelasticity are also discussed. The influences of both dynamic and fatigue loadings are studied as well. Discussion on the fiber blending and on the behavior of blended hybrid structures is provided. Further, a special section is included in which six specific topical areas, their significance toward textile science, and the progress made in these areas are introduced and summarized. Finally, experimental issues are discussed. Although this article is intended to serve as a complete review of the subject, because of the limit of both time and space, we can only focus on the areas in which we are most familiar. This article, therefore, is by no means exhaustive or authoritative in every topic discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 610–630, 2002
Super‐osteons (remodeling clusters) in the cortex of the femoral shaft: Influence of age and gender
Authors: Bell Karen L. , Loveridge Nigel , Reeve Jonathan , Thomas Christopher D.L. , Feik Sophie A. , Clement John G.
Published: August 2002

Previous studies of cortical remodeling in the fractured femoral neck indicated that the merging of spatially clustered remodeling osteons could result in the formation of deleteriously large cavities associated with femoral neck fracture. This study aimed to identify whether remodeling osteons in the femoral shaft were also clustered and to assess the influence of age and gender. Microradiographic images of femoral mid‐shaft cross‐sections from 66 subjects over 21 years of age were analyzed to determine the number, size and location of all Haversian canals. Those most recently remodeled were identified using an edge‐detection algorithm highlighting the most marked differential gradients in grey levels. Cluster analysis (JMP software) of these osteons identified the proportion of recently remodeled osteons that were within 0.75mm clusters. As in the femoral neck, remodeling osteons were significantly more clustered than could occur by chance (real, 59.4%; random, 39.4%; P < 0.0001). The density of these clusters (number/mm2) was not significantly associated with subject age or gender but was greatest near the periosteum and decreased toward the marrow cavity (periosteal 0.043 ± 0.004; mid‐cortex 0.028 ± 0.003; endosteal 0.017 ± 0.002). Cortical porosity increased with age. The presence of giant canals (diameter >385μm) was inversely related to the presence of clusters (R2 = 0.237, P < 0.0001). This data suggest that remodeling osteons tend to be spatially colocalized in the shaft as they are in the neck of the femur and their presence is independent of age or gender. We propose that these remodeling clusters be termed super‐osteons. The negative relationship between super‐osteons and giant canals raises the intriguing possibility that loss of the control of remodeling depth results in the merging of osteonal systems to form deleteriously large cortical cavities with a marked reduction in bone strength. Anat Rec 264:378–386, 2001. © 2001 Wiley‐Liss, Inc.
Luminal morphology of the avian lower intestine: Evidence supporting the importance of retrograde peristalsis for water conservation
Authors: Casotti Giovanni
Published: August 2002

Tissue from the lower intestine of two species of sparrow, the house sparrow Passer domesticus and savannah sparrow Passerculus sandwichensis was sectioned in an unbiased manner and examined quantitatively using stereology. The tissue was processed for light microscopy, and scanning and transmission electron microscopy to examine the extent to which microvilli enhanced the epithelial surface area of the cecae, rectum, and coprodeum. Parameters measured included individual microvillus surface area, microvilli packing density, and absolute surface area. In both species, the average surface area, packing density, and absolute surface area of microvilli decreased distally along the rectum and coprodeum. All three measured variables were not statistically significant (P > 0.05) between species. Surface area amplification on the cecae due to microvilli was low, and approximated values equivalent to distal regions of the rectum and coprodeum. In the cecae, microvilli within the savannah sparrow had a significantly higher (P < 0.05) individual surface area, packing density, and absolute surface area than in the house sparrow. The functional implications of a change in microvilli population are discussed in relation to retrograde peristalsis within the lower intestine of birds. Anat Rec 263:289–296, 2001. © 2001 Wiley‐Liss, Inc.
Reappraisal of the vomeronasal system of catarrhine primates: Ontogeny, morphology, functionality, and persisting questions
Authors: Smith Timothy D. , Siegel Michael I. , Bhatnagar Kunwar P.
Published: August 2002

The vomeronasal organ (VNO) is a chemosensory organ that functions in sociosexual communication in many vertebrates. In strepsirhine primates and New World monkeys, the bilateral VNOs are traditionally understood to exist as a well‐developed chemosensory epithelial unit. In contrast, the VNOs of catarrhine primates are thought to be absent or exist only as reduced epithelial tubes of uncertain function. However, the VNO of New World monkeys shows substantial variation in the extent of sensory epithelium. Recent findings that the chimpanzee (Pan troglodytes) possesses a VNO similar to humans suggest the variability of the VNO among haplorhine primates may be more extensive than previously thought, and perhaps more at par with that observed in chiropterans. The atypical histologic structure and location of the human/chimpanzee VNO suggest accessory glandular secretion and transport functions. Other catarrhine primates (e.g., Macaca spp.), may truly be characterized by VNO absence. Unique aspects of facial growth and development in catarrhine primates may influence the position or even presence of the VNO in adults. These recent findings demonstrate that previous investigations on some catarrhine primates may have missed the VNO and underestimated the extent of variability. As an understanding of this variation increases, our view of VNO functionality and associated terminology is changing. Further investigations are needed to consider phylogenetic implications of VNO variability and the association of craniofacial form and VNO anatomic position in primates. Anat Rec (New Anat) 265:176–192, 2001. © 2001 Wiley‐Liss, Inc.
Introduction
Authors: Stanley David W.
Published: August 2002

Colleagues,

It is a pleasure to introduce a group of three papers on insect G protein‐coupled receptors, from a symposium organized by Professor Jozef Vanden Broeck. This symposium, held August, 2000 at the XXI International Congress of Entomology in Brazil, represents one of the frontiers of biology and insect science. Professor Vanden Broeck has agreed to serve as Guest Editor for these papers, in which the contributors illuminate that frontier.

Study of signal transduction mechanisms is a unifying, multidisiplinary activity that links many traditional fields of biology. Extracellular signals influence events within cells through a number of signal transduction mechanisms. G protein‐coupled receptors is one of the mechanisms. Many ligands, including hormones, prostaglandins and biogenic amines to name just a few, exert their cellular actions by interacting with specific G protein‐coupled receptors. Appreciating the broad variety of these receptors and the associated signal transducton mechanisms is a major advance in our field. We invite you to share in the insights and excitement of this advance.
XML and free text
Authors: Roger Riggs Ken
Published: August 2002

We show several problems with marking free text, text that is either natural language or semigrammatical but unstructured. These problems prevent well‐formed XML from marking text for readily available meaning. A solution is proposed to mark meaning in free text that is consistent with the intended simplicity of XML versus SGML.