bluuebunny/crossref_metadata_2025_split huggingface dataset:
EVOH/clay nanocomposites produced by dynamic melt mixing
Authors: Artzi N. , Narkis M. , Siegmann A. 
Published: July 2004

AbstractEthylene‐vinyl alcohol copolymer (EVOH)/clay nanocomposites were prepared via a dynamic melt‐intercalation process using a Brabender Plastograph or extruder. The phase morphology and the crystallization behavior of the nanocomposites were investigated, using differential scanning calorimetry (DSC), X‐ray diffraction (XRD), and transmission electron microscopy (TEM). Mechanical properties were determined using an Instron machine. It was found that the viscosity of EVOH/clay mixtures increases with processing time. Thermal analysis of the EVOH/clay nanocomposites showed that the melting temperature, crystallization temperature, and heat of fusion of the EVOH matrix sharply decrease when clay is added. XRD verified an increased gallery height for the clay in the composites. Maleic anhydride–grafted ethylene vinyl acetate (EVA‐g‐MA) or maleic anhydride–grafted linear low‐density polyethylene (LLDPE‐g‐MA) were added as compatibilizers of EVOH with clay, in various concentrations (1, 5 and 10 wt%). Significantly higher viscosity levels were obtained for the compatibilized systems as the torque dramatically increased when processed in the Brabender machine. Enhanced intercalation within the galleries was obtained. EVOH crystallinity decreased with increasing compatibilizer content, until at a certain content no crystallization took place. EVOH/clay composites were also processed in an extruder, showing improved mechanical properties for as low as 1 wt% clay. The strong EVOH/clay interactions are responsible for the unique behavior of their nanocomposites. Polym. Eng. Sci. 44:1019–1026, 2004. © 2004 Society of Plastics Engineers.
Cure kinetics of epoxy systems modified with block copolymers
Authors: Larrañaga M , Martín MD , Gabilondo N , Kortaberria G , Corcuera MA , Riccardi CC , Mondragon I 
Published: July 2004

AbstractThe kinetics pathway of a 4,4′‐diaminodiphenylmethane‐cured diglycidyl ether of bisphenol‐A (DGEBA) epoxy system modified with a PEO–PPO–PEO block copolymer has been investigated by differential scanning calorimetry. The curing progress of this system has also been studied by dielectric relaxation spectrometry following changes in the main α‐relaxation. An interesting finding is the change in rate constant with copolymer content. Infrared spectroscopy shows that this change is due to interactions between the hydroxyl groups of the growing epoxy thermoset and the ether bonds of the block copolymer. The proposed phenomenological autocatalytic model provides a good description of the cure behaviour of this epoxy/copolymer system for all cure cycles used. Copyright © 2004 Society of Chemical Industry
Electric self‐heating behavior of acetylene carbon black filled high‐density polyethylene composites
Authors: Song Yihu , Zheng Qiang 
Published: July 2004

AbstractThe electric self‐heating behavior of carbon black (CB) filled high‐density polyethylene (HDPE) was studied in relation to the time‐dependent current and surface temperature under various voltages and to the voltage‐dependent surface temperature at electric–thermal equilibrium. The resistance increase due to self‐heating restricts the current flow through the sample and thus stabilizes the electric power and the self‐heating temperature to their saturation values, which vary with the voltage. A simple phenomenological model shows that self‐heating at electric‐thermal equilibrium is involved in the initial resistance, the electric field induced positive temperature coefficient (PTC) transition and the heat dissipation. The influences of annealing and irradiation crosslinking on the self‐heating behavior are discussed. Copyright © 2004 Society of Chemical Industry
Urea and formamide as a mixed plasticizer for thermoplastic starch
Authors: Xiaofei Ma , Jiugao Yu , Jin Feng 
Published: July 2004

AbstractMixtures of urea and formamide were tested as plasticizers for thermoplastic starch (TPS). The hydrogen bonding interactions between urea/formamide and starch were investigated by using Fourier‐transform infrared spectroscopy (FT‐IR). The thermal stability, mechanical properties and starch retrogradation behavior were also studied by thermogravimetric analysis (TGA), tensile testing and X‐ray diffraction (XRD), respectively. TPS plasticized by urea (20 wt%) and formamide (10 wt%) showed better thermal stability and water resistance than conventional TPS plasticized by glycerol. Moreover, the tensile stress, strain and energy at break, respectively, reached 4.83 MPa, 104.6 % and 2.17 N m after storing in an atmosphere of relative humidity (RH) of 33 % for one week. At the same time, this mixed plasticizer could effectively restrain the retrogradation of starch. Copyright © 2004 Society of Chemical Industry
Fast, contactless and spatially resolved measurement of sheet resistance by an infrared method
Authors: Isenberg Joerg , Biro Daniel , Warta Wilhelm 
Published: July 2004

AbstractThe principle of free carrier absorption in combination with a CCD camera sensitive in the infrared is used to establish a measurement method for the emitter sheet resistance of silicon solar cells. This combination allows for extremely fast measurements. For example a 100 × 100 mm wafer may be measured with a spatial resolution of 350 μm within less than 10 s.An additional advantage of the optical measurement of emitter sheet resistance is the ability to measure inhomogeneities with an extremely good spatial resolution without errors due to size and orientation of the probe, which occur regularly in electrical measurements as, e.g., four‐point probing if a spatial resolution of the order of or below the size of the probe is required. In the set‐up presented spatial resolutions as low as 50 μm were realized, but even higher resolutions would be attainable with an appropriate lens system. The measurement requires a solar cell precursor after emitter diffusion, but before metalization. Additionally a reference without emitter, but with identical surface properties is needed.The high spatial resolution facilitates a detailed investigation of selective emitters and a comparison of the results obtained by four‐point probing. It is shown that the method developed here allows a considerably better quantitative evaluation of these structures than electrical measurements. Additionally the technique is used to test and optimize the homogeneity of a diffusion furnace. Copyright © 2004 John Wiley & Sons, Ltd.
Childhood‐onset schizophrenia: An overview
Authors: Gonthier Misty , Lyon Mark A. 
Published: July 2004

AbstractChildhood‐onset schizophrenia (COS), particularly when diagnosed prior to the age of 13, is considered to be especially rare and severe. This article provides an in‐depth look into its symptomatology, general course, long‐term functioning, diagnostic criteria, and methods of assessing the disorder. It also includes discussions of the various treatments used with patients having COS, including psychopharmalogical treatments, cognitive therapy, family interventions, educational interventions, and environmental manipulations. Particular attention is paid to the educational implications of the disorder and the role of school psychologists in working with this population. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 803–811, 2004.
Crisis prevention and intervention: A survey of school psychologists
Authors: Nickerson Amanda B. , Zhe Elizabeth J. 
Published: July 2004

AbstractA random sample of 197 practicing school psychologists who were members of the National Association of School Psychologists (NASP) completed a survey questionnaire on experiences and perceptions with regard to school crisis preparedness, prevention, and intervention. Respondents indicated having the most direct experience with student–student physical assaults, serious illness or injury of students, unexpected students deaths, suicide attempts, and guns or other weapons at school. School psychologists reported that their schools used a wide variety of prevention and intervention strategies, most of which have been advocated in the literature. Respondents reported being most involved in the implementation of crisis prevention and intervention strategies and less involved in development and evaluation. Results and implications are discussed within the context of empirically supported practices and school psychologists' readiness to assume larger roles in crisis prevention and intervention. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 777–788, 2004.
The early assessment conundrum: Lessons from the past, implications for the future
Authors: Bordignon Catherine M. , Lam Tony C.M. 
Published: July 2004

AbstractThe early childhood educational field has garnered attention with initiatives to foster skill acquisition in young children prior to kindergarten entry. These initiatives, in conjunction with the rigorous demands of curricular reform and a burgeoning accountability movement, invoke questions regarding the adequacy of the instruments used to assess young children and the inherent difficulties in conducting such assessments. Because the effectiveness of education relies critically on the sound diagnoses of children's readiness for learning and the measurement of their subsequent progression throughout the schooling process, critical issues in early assessment must be addressed. An examination of past practices was synthesized with recent research to focus awareness on the insufficient content domain, restrictive context, adverse timing and questionable psychometric properties, specifically the inappropriate norms and low predictive validity, of many instruments. Both the implications of and compensatory strategies for each issue are considered. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 737–749, 2004.
Syntheses of bisazo‐containing polymethacrylates using atom transfer radical polymerization and the photoalignment behavior
Authors: Jin Ming , Xin Yang Qing , Lu Ran , Hua Xu Ting , Ying Zhao Ying 
Published: July 2004

AbstractThree kinds of photoresponsive polymethacrylates containing different bisazo chromophores were prepared with atom transfer radical polymerization and characterized with proton nuclear magnetic resonance, gel permeation chromatography, and ultraviolet–visible spectra. These polymers had similar molecular weights, molecular weight distributions, glass‐transition temperatures, and absorption coefficients. The irradiation of these polymer films with a linearly polarized laser could induce birefringence because of the reorientation of the bisazo chromophores through trans–cis–trans isomerization cycles of double azo bonds, and the corresponding mechanism was also examined. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4237–4247, 2004
Science as a map in technological search
Authors: Fleming Lee , Sorenson Olav 
Published: July 2004

AbstractA large body of work argues that scientific research increases the rate of technological advance, and with it economic growth. The precise mechanism through which science accelerates the rate of invention, however, remains an open question. Conceptualizing invention as a combinatorial search process, this paper argues that science alters inventors' search processes, by leading them more directly to useful combinations, eliminating fruitless paths of research, and motivating them to continue even in the face of negative feedback. These mechanisms prove most useful when inventors attempt to combine highly coupled components; therefore, the value of scientific research to invention varies systematically across applications. Empirical analyses of patent data support this thesis. Copyright © 2004 John Wiley & Sons, Ltd.
Subsidiaries and knowledge creation: the influence of the MNC and host country on innovation
Authors: Almeida Paul , Phene Anupama 
Published: July 2004

AbstractThis paper studies the influence of external knowledge on innovation in subsidiaries of multinational firms. The focus on subsidiaries is especially interesting since they are simultaneously embedded in two knowledge contexts: (a) the internal multinational corporation (MNC) comprised of the headquarters and other subsidiaries; and (b) an external environment of regional or host country firms. We develop hypotheses to suggest that the extent of influences of these contexts on subsidiary technological innovation depends on the characteristics of the knowledge network (technological richness and diversity) and the knowledge linkages of the subsidiary with other entities. The study uses patent citation data pertaining to innovations by foreign subsidiaries of U.S. semiconductor firms to test these hypotheses. The paper finds that (a) the technological richness of the MNC, (b) the subsidiary's knowledge linkages to host country firms, and (c) the technological diversity within the host country have a positive impact on innovation. Copyright © 2004 John Wiley & Sons, Ltd.
Usefulness of Known Computed Tomography and Clinical Criteria for Diagnosing Strangulation in Small‐Bowel Obstruction: Analysis of True and False Interpretation Groups in Computed Tomography
Authors: Kim Jung Hoon , Ha Hyun Kwon , Kim Jeong Kon , Eun Hyo Won , Park Kwang Bo , Kim Bong Soo , Kim Tae Kyoung , Kim Jin Chen , Auh Yong Ho 
Published: July 2004

AbstractComputed tomography (CT) criteria have proven useful, but not sufficient, for diagnosis of bowel strangulation. The purpose of the present study was to evaluate the useof clinical criteria in the interpretation of CT scans as a means of improving the diagnostic accuracy of CT, especially in patients whose CT scans are equivocal for distinguishing simple obstruction from strangulated obstruction. We analyzed the CT scans of 136 patients with simple (n = 70) or strangulated (n = 66) small‐bowel obstruction. Three radiologists interpreted the CT scans independently for the presence of intestinal strangulation. According to their interpretation, 136 patients were divided into two groups, i.e., a false and a true interpretation group. The diagnostic value of known CT and four clinical criteria (tenderness, tachycardia, fever, and leukocytosis) were compared in the two groups. The diagnostic accuracy of CT criteria for distinguishing simple obstructions from strangulated small‐bowel obstructions ranged between 73% and 80%. Of the 136 patients, 31 belonged to the false group and 105 to the true group. The CT criteria that were highly specific in both groups included severe mesenteric haziness, serrated beak, and poor bowel wall enhancement. Among the clinical criteria, both tachycardia and leukocytosis were highly specific in both groups. The number of positive clinical criteria was helpful in making a diagnosis; none or one clinical criterion indicated a simple obstruction, whereas three or four criteria indicated a strangulated obstruction; when this result was applied retrospectively to the false group, the CT diagnostic accuracy improved in 19 of the 31 patients. The use of clinical criteria when CT findings are equivocal, may overcome the inherent limitations of CT for diagnosing strangulated small‐bowel obstruction.
Hydatid Cysts of the Adrenal Gland: Review of Nine Patients
Authors: Akçay Müfide Nuran , Akçay Güngör , Balik A. Ahmet , Böyük Abdullah 
Published: July 2004

AbstractAdrenal cysts are very rare lesions, especially with parasitic origin. But with the wider application of ultrasonography (US) and computed tomography (CT) more adrenal cysts are detected incidentally. To gain more insight into this entity, the records of nine patients with hydatid cysts of adrenal gland seen at our department from January 1980 till January 2002 are reviewed. There were four men and five women, and their ages ranged from 15 to 80 years (median: 41 years). All of the patients had unilateral cysts. Seven cysts were located on the right and two on the left side. Five of the cysts were primary and four were secondary. In three patients the cysts were found incidentally. The most common presenting symptom was pain, which was present in six patients. An indirect hemagglutination (IHA) test was positive in six cases. In all patients, US and CT successfully imaged all cysts, but the definitive diagnosis was made by macroscopic and microscopic examination of the cyst’s content. The patients were treated surgically. In all patients adrenal glands with the cystic masses were removed. The median follow‐up period was 16 months (range: 6–64 months). No evidence of recurrence was found in any patient. It should not be forgotten that cystic masses of the upper abdomen might also originate from the adrenal gland. The etiology and nature of the cyst should be well researched, and appropriate treatment should be given as soon as possible. Surgical excision of the gland, including the cyst is the treatment of choice.
Gallbladder Cancer in the Twentieth Century: Single Institution’s Experience
Authors: Grobmyer Stephen R. , Lieberman Michael D. , Daly John M. 
Published: July 2004

AbstractThe purpose of this study was to understand trends in the presentation, management, and outcome of patients of patients with gallbladder cancer treated over a period of 85 years at a single institution. We analyzed patients with gallbladder carcinoma treated at our institution between 1990 and 2000 (n = 66). Data from this series were analyzed in the context of previously reported series from our institution (beginning in 1915) to understand trends in the presentation, management, and outcome of patients with gallbladder carcinoma. The mean age of patients has increased from 53.6 years (1915–1932) to 65.0 years (1990–2000). The gender (73% female) distribution of patients and most the common presenting symptoms (abdominal pain, weight loss, jaundice, nausea, abdominal mass) have not changed over the 85 years. More extensive surgery is being performed on patients with gallbladder carcinoma. The mean survival of patients with gallbladder cancer has increased from 3.6 months (1915–1932) to 10.0 months (1990–2000). The presentation of patients with gallbladder cancer has not changed over the 85 years. Most patients still present with advanced disease. The overall survival of patients with gallbladder cancer is poor, but it has improved since 1915.
Acute Respiratory Distress Syndrome in the Septic Surgical Patient
Authors: Balibrea Jose L. , Arias‐Díaz Javier 
Published: July 2004

AbstractThe acute respiratory distress syndrome (ARDS) is a process of acute inflammatory lung injury that affects a diverse array of surgical and medical patients. The syndrome is mediated by a complex and interacting system of chemical mediators produced by several types of pulmonary cells. Regardless of the predisposing causes, activation of the nuclear factor kappa B seems to be, at the molecular level, a signature event of ARDS, leading to the rapid activation of intracellular signaling pathways, which coordinate the induction of multiple genes encoding inflammatory mediators. There are at least two compelling reasons for promoting an understanding of these interactions and their molecular mediators and second messengers: new therapies intended to modulate these factors continue to be developed, and the levels of some of these molecules, most notably cytokines, may serve as early indicators of the onset of ARDS.
Presence and localization of epidermal growth factor (EGF)‐ and EGF‐receptor‐like immunoreactivity in Tetrahymena
Authors: Csaba G. , Kovács P. , Pállinger Éva 
Published: July 2004

AbstractThe presence of EGF‐ and EGF‐receptor‐like immunoreactivity in Tetrahymena was studied with the help of FITC‐labelled monoclonal antibodies, using flow cytometry and confocal microscopy. Tetrahymena has endogeneous EGF and treatment with it significantly increases the hormone content of the cells. The hormone is diffusely localized, particularly in the cytopharynx, where it forms a structure larger than 10 μm. EGF‐receptors are also demonstrable, particularly in the cortical region in connection with cilia, and EGF treatment significantly enhances cortical fluorescence. The relationships between these observations and literary data on the effects of EGF in Tetrahymena are discussed.
Cell division induced by mechanical stimulation in starved Tetrahymena thermophila: cell cycle without synthesis of macronuclear DNA
Authors: Iwamoto Masaaki , Sugai Toshiro , Nakaoka Yasuo 
Published: July 2004

AbstractStarved Tetrahymena thermophila cells underwent synchronous cell division 2 h after a mechanical stimulation. The macronucleus showed no obvious increase in DNA content before the cell division in the starvation medium, and the DNA content was decreased after the cell division. On the other hand, when the starved cells were given nutrient‐supplied medium immediately after the mechanical stimulation, cell division was delayed for 3 h. This period was almost the same as that for G1 cells in the stationary culture to first division after transfer to fresh nutrient medium. These results suggest that the mechanical stimulation induces an early division of starved cells, skipping the macronuclear S‐phase with the starved cells probably becoming trapped in G1. Starved cells that had finished division soon formed mating pairs with cells of the opposite type. These observations lead us to propose that cell division in starvation conditions may be necessary to reduce macronuclear DNA content prior to the mating of T. thermophila.
Effect of stress‐induced lipid peroxidation on functions of rat peritoneal macrophages
Authors: Nimet İzgüt‐Uysal V. , Tan Ruken , Bülbül Mehmet , Derin Narin 
Published: July 2004

AbstractThe aim of the present study was to investigate the effects of stress‐induced lipid peroxidation on macrophages' functions. Animals were subjected to 4 h immobilization at 4 °C in restraining devices. The peritoneal macrophages obtained from rats exposed to cold and restraint stress exhibited an increase in lipid peroxidation and a decline of chemotaxis and phagocytosis compared with control rats. After supplementation with vitamin E, the increment in thiobarbituric acid reactive substances (TBARS) content as the oxidative stress marker and the decline of chemotaxis and phagocytosis in peritoneal macrophages observed during cold‐restraint stress was significantly removed. No significant change in catalase activity of peritoneal macrophages was observed in groups exposed to cold‐restraint stress and treated with vitamin E. These findings indicate that phagocytic and chemotactic capacities of peritoneal macrophages are decreased by cold‐restraint stress and this effect of stress may be related to lipid peroxidation.
Enrichment and characterization of mouse putative epidermal stem cells
Authors: Zhou Jia‐xi , Jia Li‐wei , Yang Yong‐jun , Peng Sha , Cao Yu‐jing , Duan En‐kui 
Published: July 2004

AbstractEpidermis, a continuously renewing tissue, is maintained by stem cells that proliferate and replenish worn out or damaged cells in the tissue during life. Cultured epidermal stem cells have great potential in scientific research and clinical application. However, isolating a pure and viable population of epidermal stem cells and culturing them has been challenging. In this study, putative epidermal stem cells of mouse were isolated by combining Hoechst 33342 and propidium iodide staining with fluorescence‐activated cell sorting. Molecular markers expression pattern analysis showed that cytokeratin 14, integrin β1 and p63 are expressed in the sorted putative stem cells, but not active β‐catenin, nestin and involucrin. Our results provide further supporting data that mouse putative epidermal stem cells could be successfully isolated by combining Hoechst dye staining with fluorescence‐activated cell sorting and cultured in vitro. The cultured mouse putative epidermal stem cells could be used as a potent tool for studying stem cell biology and testing stem cell therapy.