bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Theory of the Calender Effect in Rubberlike Materials
Authors: Bilmes L. 
Published: February 2011

Abstract
The facts relating to the calender effected are briefly stated and illustrated by experimental data obtained with calendered plasticized polyvinyl chloride sheet. The nature of rubberlike deformation is outlined. A theory of the calender effect is proposed in terms of a mechanical model whose relation to molecular structure is indicated. The theory postulates that temperature-dependent yield values be associated with the mechanisms of high elastic deformation and plastic flow.
The State of Polydispersion of Hevea Latex. I
Authors: Hessels J. H. E. 
Published: February 2011

Abstract
The rubber particles in the latex of Hevea brasiliensis are present in the form of a polydispersion, and their diameters lie within the range of 0.1 to 3 microns. The rubber hydrocarbon itself is composed of a mixture of macromolecules of different degrees of polymerization. Rubber latex is, therefore, a system which is at the same time both polydispersed and polymolecular. It is well known that the degree of dispersion of a substance governs to a great extent certain properties of the substance. Moreover, astonishing as it may seem, in the great number of investigations which have been made of the composition and properties of latex and crude rubber, almost no attention has been paid to the part which may be played by the dimensions of the latex particles. However, in an investigation concerned with the centrifugation of latex, Loomis and Stump have called attention to this possibility, and in a study of latex obtained by fractionation, and in which the majority of the latex particles were of large dimensions, McGavack came to the conclusion that the protein content is proportional to the surface area of the globules. This limited knowledge of the subject seemed to warrant a more thorough study of the problem, which is of fundamental importance both from the theoretical and practical points of view. The investigation as a whole divided itself into three essential parts: (1) separation of latex into fractions containing particles of different sizes, and measurement of the state of dispersion in these fractions, (2) a study of the relation of these fractions to the composition of the rubber, i.e., the relation between the content of nonrubber components and the size of the latex particles, and (3) a study of the changes in the properties of the rubber hydrocarbon with change in the size of the latex particles. The latex used in this investigation was ordinary latex, containing 38–40 per cent dry-rubber content and preserved with ammonia. For the most important points, a concentrated latex (creamed latex containing 60 per cent dry-rubber content) was also tested. These two latices were about two years old when the investigation was started, and they gave results which were in good agreement with each other. In the present paper, only the data obtained with the first of the two latices are presented.
Extraction of Rubber from Cryptostegia Grandiflora
Authors: Bhatnagar S. S. , Shankar Karimullah , Shankar Uma 
Published: February 2011

Abstract
In an earlier communication on the subject, it was.stated that an improved method for the extraction of rubber from harvested partially dry twigs of Cryptostegia grandiflora, which has assumed considerable importance as a secondary source of rubber, has been worked out in these laboratories. The facts that (1) its latex is distributed throughout the plant (unlike Hevea, in which the latex cells are localized in a definite region in the cortex), and (2) its latex does not ooze out in a continuous stream, but coagulates very soon at the cut surface, rendered it necessary to develop either a modified tapping technique involving decapitation of shoots and collection of “plugs,” or a process in which the entire plant or the harvested shoots are suitably treated to release their rubber. The Rubber Directorate, it is understood, are experimenting with modified tapping methods, which have proved to be somewhat cumbersome and uneconomical. At the instance of the Supply Department, investigations were undertaken in these laboratories to develop a more convenient and economical process for the extraction of rubber from the plant.
Control of Elongation in Highly Stretched Cotton Tire Cord
Authors: Philipp Howard J. , Conrad Carl M. 
Published: February 2011

Abstract
1. Cotton tire cords, differing with regard to gauge, construction, and variety of cotton, were subjected to stretching treatments involving various combinations of tension, heat, and moisture. It was found that all these treatments increased the strength of the cords but reduced their gauge and elongation at 10 pounds. The greatest increase in strength was obtained when tire cord was stretched in a swollen condition and in the presence of heat. Increases in count-strength product from 48 to 83 per cent were observed. 2. Experiments showed a reciprocal relationship between the strength and the elongation at 10 pounds obtainable by single-stretching treatments of tire cord, which makes impossible the control of elongation, independently of strength. Bone-dry elongations of about 6 per cent at 10 pounds could be obtained only with negligible increase in strength. 3. The original elongation was restored by treating highly stretched tire cord with water at room temperature for 30 minutes or with boiling water for 3 minutes, while most of the increase in strength resulting from stretching was retained. A hot-wet-stretched tire cord after treating with water had equal elongation but greater strength as compared with the untreated cord. 4. A dual-stretching method was devised which makes possible the control of elongation at 10 pounds independently of strength. The treatment consists of two phases : the first imparts to the cord the maximum potential breaking strength and the second serves to adjust the elongation at 10 pounds to a predetermined controlled value while maintaining over 90 per cent of the maximum count-strength product. Control of the elongation is achieved by proper selection of tension and degree of swelling during the second phase of the dual-stretching treatment.
The Nature of the Dynamic Double Refraction of Rubber Solutions and the Shape of Rubber Molecules
Authors: Tsvetkov V. , Petrova A. 
Published: February 2011

Abstract
The work which is described in the present paper is concerned with the development of a method for measuring the double refraction of a flowing liquid, with particular attention to a study of the structure of polymers. The dependence of double refraction and of the angle of extinction on the velocity of flow of solutions of thirty samples of synthetic rubber through a wide range of velocities was studied. For linear polymers having high molecular weights, the relation: Δn=ƒ(g), shows, when represented graphically, an ascending concave curve. This relation is rectilinear for all polymers whose molecular weights lie within the usual range. In all cases investigated, the angle of extinction lay within the limits of 45° and 0°. The dynamic optical constant which characterizes the double refraction of rubber was established experimentally. This dynamic optical constant was calculated for all samples of rubbers which were studied. Three effects on the double refraction of a solution of a polymer during flow were distinguished experimentally: (1) the effect of the shape of the particles; (2) the effect of the anisotropy of the particles ; and (3) the elastic effect. The double refraction of solutions of synthetic rubbers in an electric field was investigated with a view to determining the anisotropy of the molecules of the polymers. On the basis of the experimental data it is concluded that the double refraction of a flowing rubber solution is fundamentally influenced by the effect of tension. The theory of Kuhn and the experimental data obtained in the present work were utilized to calculate the relation between the transverse and longitudinal dimensions of all the rubbers which were studied.
Weathering of Soft Vulcanized Rubber
Authors: Crabtree James , Kemp A. R. 
Published: February 2011

Abstract
When rubber goods are exposed to the agencies which constitute “weather”, they undergo profound changes. The rubber may lose elasticity, it may split or crack, or the surface may take on a crinkled appearance in a wide variety of designs. Figure 1 shows a small selection of such weathered rubbers. The course of deterioration, or the ultimate condition of any particular rubber specimen, moreover, is not always the same, but depends to a considerable extent on the kind of weather encountered which, in turn, depends on geography, topography, and season. The components of weather are air, heat, water, and sunlight, each varying in quantity and quality so that infinite combinations are possible. Among the major (nitrogen and oxygen), minor (carbon dioxide, argon, helium, neon, krypton, xenon), and trace (ozone, nitrogen oxides, ammonia, sulfur dioxide, sulfuric acid, hydrogen sulfide, carbon monoxide, hydrocarbons, hydrogen, mineral salts, hydrogen peroxide, organic peroxides) components of the atmosphere, only oxygen, ozone, and nitrogen oxides are capable of reacting with rubber. Trial shows steadily that, of these, only oxygen and ozone produce any perceptible effect at the concentrations in which they are present.
Early Cannulation Prosthetic Graft (Flixene™) for Arteriovenous Access
Authors: Schild A. Frederick , Schuman Earl S. , Noicely Karlene , Kaufman Joyce , Gillaspie Erin , Fuller Joseph , Collier Patrick , Ronfeld Amy , Nair Rakesh Ravikumaran 
Published: February 2011

Purpose Preferred hemodialysis (HD) access is an autologous fistula. Vascular grafts are used in patients with vessels unsuitable to accomplish an arteriovenous fistula (AVF). It is recommended that most current grafts mature in situ for 2–3 weeks before being accessed. Graft complications occur because the structure was not designed for the trauma of repeated cannulation. This study graft has a different structure that enables early use. Its design minimizes weeping through the graft walls and is meant to endure repeated access, thus minimizing the use of HD catheters. The purpose of this study was to show that the Flixene™ graft can be safely placed in patients where fistulas have failed and can be cannulated in 24–72 hr, while maintaining patency rates similar to other polytetrafluoroethylene (PTFE) grafts on the market. Flixene™ configuration should also reduce the incidence of pseudoaneurysms and seromas. Methods A prospective two-center study placed 33 grafts in 33 patients; graft efficacy, post-operative complications, and patency were evaluated. Ease of cannulation and dialysis center complications related to early cannulation were documented. Six month follow-up data was analyzed. Results Successful access was achieved in all 33 patients within 72 hr (29 patients within 24 hr). Overall primary patency at 6 months was 49%; primary-assisted patency at 6 months was 80%. No pseudoaneurysms or seromas were documented at 6 months. Complications were typical of graft access. Conclusion Early cannulation was successful in all patients. Primary and secondary patency rates at 6–months were equivalent to other data reported on PTFE grafts. Flixene™ successfully prevented pseudoaneurysm and seroma formation at 6 months of prospective follow-up. This graft is a better last-resort option for patients who cannot receive a fistula, compared to double-lumen cuffed catheters.
Caco‐2 Cells as a Model for Intestinal Absorption
Authors: Angelis Isabella De , Turco Laura 
Published: February 2011

AbstractThe Caco‐2 cell system, a well characterized intestinal in vitro model, makes it possible to evaluate the ability of chemicals to cross the intestinal barrier, as well as to study their transport mechanisms. Permeability values estimated with this model correlate well with human in vivo absorption data for many drugs and chemicals. As a consequence, the use of the Caco‐2 cellular model as a permeability assay to predict oral absorption in humans is growing, and its importance is increasing as a screening tool in drug‐discovery strategies for the prediction of intestinal drug permeability. Strict observance of the experimental conditions, coupled with careful control of the cell‐culture procedures, are crucial for obtaining a meaningful correlation with in vivo data. Because of the intrinsic variability of this absorption model, it is important to highlight that each experimental system must be calibrated with internal reference compounds, to permit data sharing between different laboratories.Curr. Protoc. Toxicol. 47:20.6.1‐20.6.15. © 2011 by John Wiley & Sons, Inc.
On stable simultaneous input and state estimation for discrete‐time linear systems
Authors: Fang Huazhen , Shi Yang , Yi Jingang 
Published: February 2011

AbstractThis work is devoted to solving simultaneous input and state estimation (SISE) problem for discrete‐time linear systems. Our aim is to develop stable SISE algorithms. By applying the minimum variance unbiased estimation technique, we derive two SISE algorithms in the presence or absence of direct feedthrough, respectively. Riccati‐like equations are formulated and presented to analyze the stability conditions of the proposed algorithms. Simulation examples are provided to further illustrate the effectiveness of the proposed algorithms and support the theoretical findings. Copyright © 2011 John Wiley & Sons, Ltd.
Inborn errors of cobalamin absorption and metabolism
Authors: Watkins David , Rosenblatt David S. 
Published: February 2011

AbstractDerivatives of cobalamin (vitamin B12) are required for activity of two enzymes in humans. Adenosylcobalamin is required for activity of mitochondrial methylmalonylCoA mutase and methylcobalamin is required for activity of cytoplasmic methionine synthase. Deficiency in cobalamin, or inability to absorb cobalamin normally, can result in accumulation of methylmalonic acid and homocysteine in blood and urine. Methylmalonic acidemia can result in metabolic acidosis which in severe cases may be fatal. Hyperhomocysteinemia along with hypomethioninemia can result in hematologic (megaloblastic anemia, neutropenia, thrombocytopenia) and neurologic (subacute combined degeneration of the cord, dementia, psychosis) defects. Inborn errors affecting cobalamin absorption (inherited intrinsic factor deficiency, Imerslund–Gräsbeck syndrome) and transport (transcobalamin deficiency) have been described. A series of inborn errors of intracellular cobalamin metabolism, designated cblA‐cblG, have been differentiated by complementation analysis. These can give rise to isolated methylmalonic acidemia (cblA, cblB, cblD variant 2), isolated hyperhomocysteinemia (cblD variant 1, cblE, cblG) or combined methylmalonic acidemia and hyperhomocysteinemia (cblC, classic cblD, cblF). All these disorders are inherited as autosomal recessive traits. The genes underlying each of these disorders have been identified. Two other disorders, haptocorrin deficiency and transcobalamin receptor deficiency, have been described, but it is not clear that they have any consistent clinical phenotype. © 2011 Wiley‐Liss, Inc.
What lies beneath? An evaluation of lower molar trigonid crest patterns based on both dentine and enamel expression
Authors: Bailey Shara E. , Skinner Matthew M. , Hublin Jean‐Jacques 
Published: February 2011

AbstractThe nearly ubiquitous presence of a continuous crest connecting the protoconid and metaconid of the lower molars (often referred to as the middle trigonid crest), is one of several dental traits that distinguish Homo neanderthalensis from Homo sapiens. This study examined variation in trigonid crest patterns on the enamel and dentine surfaces to (1) evaluate the concordance between the morphology of trigonid crests at the inner dentine and the outer enamel surfaces; (2) examine their developmental origin(s); and (3) examine trait polarity through comparison with Australopithecus africanus and Pan. The sample included 73 H. neanderthalensis, 67 contemporary H. sapiens, 5 A. africanus, and 24 Pan lower molars. Results indicate general agreement in the morphology observed on the dentine and enamel surfaces. All but one H. neanderthalensis molar shows some trigonid crest development, whereas trigonid crests occur in low frequency in contemporary humans. Pan and A. africanus both also show high frequencies of a continuous trigonid crest. However, the origin of the trigonid crest differs among groups. H. neanderthalensis uniquely possesses a ‘middle’ trigonid crest that originates from the mesial accessory ridge of one or both cusps. Based on our results we suggest that presence of a continuous middle trigonid crest at the dentine surface is primitive and the lack of any trigonid crest is derived. Genetic drift may explain the high frequency of trigonid crests in H.neanderthalensis. However, H. neanderthalensis still appears to be derived relative to Pan and A. africanus in its high frequency of the mesial‐mesial trigonid crestconfiguration. Am J Phys Anthropol, 2011. © 2011 Wiley‐Liss, Inc.
Mitochondrial DNA structure in North Africa reveals a genetic discontinuity in the Nile Valley
Authors: Fadhlaoui‐Zid Karima , Rodríguez‐Botigué Laura , Naoui Nejib , Benammar‐Elgaaied Amel , Calafell Francesc , Comas David 
Published: February 2011

AbstractHuman population movements in North Africa have been mostly restricted to an east‐west direction due to the geographical barriers imposed by the Sahara Desert and the Mediterranean Sea. Although these barriers have not completely impeded human migrations, genetic studies have shown that an east‐west genetic gradient exists. However, the lack of genetic information of certain geographical areas and the focus of some studies in parts of the North African landscape have limited the global view of the genetic pool of North African populations. To provide a global view of the North African genetic landscape and population structure, we have analyzed ∼2,300 North African mitochondrial DNA lineages (including 269 new sequences from Libya, in the first mtDNA study of the general Libyan population). Our results show a clinal distribution of certain haplogroups, some of them more frequent in Western (H, HV0, L1b, L3b, U6) or Eastern populations (L0a, R0a, N1b, I, J) that might be the result of human migrations from the Middle East, sub‐Saharan Africa, and Europe. Despite this clinal pattern, a genetic discontinuity is found in the Libyan/Egyptian border, suggesting a differential gene flow in the Nile River Valley. Finally, frequency of the post‐LGM subclades H1 and H3 is predominant in Libya within the H sequences, highlighting the magnitude of the LGM expansion in North Africa. Am J Phys Anthropol, 2011. © 2011 Wiley‐Liss, Inc.
Preparation and characterization of mesoporous activated carbons from waste tyre
Authors: Song X. H. , Xu R. , Lai A. , Lo H. L. , Neo F. L. , Wang K. 
Published: February 2011

ABSTRACTMesoporous activated carbon was prepared from waste tyres via acid wash and steam activation. The effect of synthetic conditions was studied and the surface texture of the tyre carbon was characterized. The optimally obtained carbon sample presents a surface area of ∼1200 m2 g−1 and is predominantly mesoporous. Acid wash was found to play an important role in the structural development of carbon. The advantage of the mesoporous carbon was demonstrated by its excellent sorption capacity towards the bulky molecule of a basic dye (methylene blue). © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.
Cluster analysis of arterial involvement in Takayasu arteritis reveals symmetric extension of the lesions in paired arterial beds
Authors: Arnaud Laurent , Haroche Julien , Toledano Dan , Cacoub Patrice , Mathian Alexis , Costedoat‐Chalumeau Nathalie , Le Thi Huong‐Boutin Du , Cluzel Philippe , Gorochov Guy , Amoura Zahir 
Published: February 2011

AbstractObjectiveThe determinants of vessel targeting are largely unknown in vasculitides. This study was undertaken to identify patterns of vascular involvement in Takayasu arteritis (TA), using objective classification of vascular beds. We postulated that cluster analysis could unveil preferential associations between vascular beds commonly affected by TA.MethodsPeripheral vascular Doppler, computed tomography angiography, and angio–magnetic resonance imaging data from 82 patients with TA (according to the American College of Rheumatology criteria) were studied between January 1995 and May 2006. Cross‐relationships of involvement between 24 main arteries were assessed using the phi correlation coefficient. Identification of patterns of vascular involvement was performed using agglomerative hierarchical cluster analysis.ResultsData were obtained from 82 patients (68 women [82.9%] and 14 men [17.1%]). The median duration of followup was 5.1 years (range 1 month to 30 years). For 16 (80%) of 20 paired arteries, the highest correlation of involvement was observed with the contralateral artery. Conversely, disease extension was contiguous in the aorta. Cluster analysis further confirmed that all paired arterial beds, except for the internal and external carotid arteries, clustered with their contralateral counterpart and that the aortic arch, the descending thoracic aorta, and the abdominal aorta clustered together.ConclusionOur findings reveal that TA lesions mostly develop in a symmetric manner in paired vascular territories and that disease extension is contiguous in the aorta. This may prove useful for improving the radiologic followup of patients with TA and for providing a pattern for further investigations focusing on the mechanisms of vessel specificity in vasculitides.
The effectiveness of pulsed electrical stimulation in the management of osteoarthritis of the knee: Results of a double‐blind, randomized, placebo‐controlled, repeated‐measures trial
Authors: Fary Robyn E. , Carroll Graeme J. , Briffa Tom G. , Briffa N. K. 
Published: February 2011

AbstractObjectiveTo determine the effectiveness of subsensory, pulsed electrical stimulation (PES) in the symptomatic management of osteoarthritis (OA) of the knee.MethodsThis was a double‐blind, randomized, placebo‐controlled, repeated‐measures trial in 70 participants with clinical and radiographically diagnosed OA of the knee who were randomized to either PES or placebo. The primary outcome was change in pain score over 26 weeks measured on a 100‐mm visual analog scale (VAS). Other measures included pain on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), function on the WOMAC, patient's global assessment of disease activity (on a 100‐mm VAS), joint stiffness on the WOMAC, quality of life on the Medical Outcomes Study Short‐Form 36 (SF‐36) health survey, physical activity (using the Human Activity Profile and an accelerometer), and global perceived effect (on an 11‐point scale).ResultsThirty‐four participants were randomized to PES and 36 to placebo. Intent‐to‐treat analysis showed a statistically significant improvement in VAS pain score over 26 weeks in both groups, but no difference between groups (mean change difference 0.9 mm [95% confidence interval −11.7, 13.4]). Similarly, there were no differences between groups for changes in WOMAC pain, function, and stiffness scores (−5.6 [95% confidence interval −14.9, 3.6], −1.9 [95% confidence interval −9.7, 5.9], and 3.7 [95% confidence interval −6.0, 13.5], respectively), SF‐36 physical and mental component summary scores (1.7 [95% confidence interval −1.5, 4.8] and 1.2 [95% confidence interval −2.9, 5.4], respectively), patient's global assessment of disease activity (−2.8 [95% confidence interval −13.9, 8.4]), or activity measures. Fifty‐six percent of the PES‐treated group achieved a clinically relevant 20‐mm improvement in VAS pain score at 26 weeks compared with 44% of controls (12% [95% confidence interval −11%, 33%]).ConclusionIn this sample of subjects with mild‐to‐moderate symptoms and moderate‐to‐severe radiographic OA of the knee, 26 weeks of PES was no more effective than placebo.