bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rubber Hydrocarbon in Freshly Tapped Latex
Authors: Bloomfield G. F. 
Published: February 2011

Abstract
Investigations carried out in Malaya have shown that rubber hydrocarbon in fresh latex is already a high molecular material but of considerable heterogeneity. Latex is separable into non-rubber constituents and rubber hydrocarbon, which is itself separable into microgel, soluble fractions covering a wide range of molecular weight, and low-molecular oxygenated fractions. The molecular weight distribution of the soluble hydrocarbon material is weighted heavily in the higher molecular weight range of half million to five million, with an average around one million. Coagulated rubber contains macrogel in addition to the microgel component of the latex. The microgel component of latex hydrocarbon has been used as a “marker” to indicate from what regions of a tree rubber is withdrawn on tapping.
Dispersion of Fillers in Rubber
Authors: Ecker Ruprecht 
Published: February 2011

Abstract
The activity of a filler in rubber depends on the size and geometrical shape of the particles, and on their chemical constitution. The smaller a particle is, the larger is the total surface area of the filler per unit weight. If, for example, the diameter of a particle of an active carbon black is 30 mµ, the total surface area is about 100 sq. m. per gram. If the particle diverges from spherical shape and has a crystalline form, the surface area is greater, as the relation of the area of a sphere to that of a cube of equal volume clearly shows (surface area of sphere: surface area of cube = 12.5:15.6). Furthermore, corners and edges are present on a particle of crystalline shape, which are particularly active according to the experimental results of interface physics. By means of this phenomenon, the differing activity of various fillers of equal particle diameter can be explained.
Polymerization Phenomena in the Vulcanization Process
Authors: Dogadkin B. , Feldstein M. , Dobromyslova A. , Shkurina V. , Kalpunov M. 
Published: February 2011

Abstract
According to theories developed by the authors, vulcanization consists essentially in the formation of local chemical van der Waals bonds (polarization, orientation bonds) and hydrogen bonds between the molecular chains of rubber. These bonds are formed as a result of the chemical reaction of the rubber with the vulcanizing agent, oxygen, and accelerators, and with other components of the vulcanizing system which contain functional groups. The essential type of chemical bonds consists of atomic groups of the vulcanizing agent (in the case of sulfur vulcanizates, “bridge” sulfur). Hypotheses were advanced concerning the course during vulcanization of the polymerization processes, initiated by the free radicals which are formed by the vulcanizing agent, and leading to the formation of —C — C—bonds between the molecular chains of the rubber. However, no proof of the existence of such processes has been obtained ; furthermore, certain data, for example, data obtained by spectral analysis, contradict such an assumption. The present paper is devoted to a description of experiments which show the existence of polymerization processes involving free radicals in vulcanized systems which contain accelerators of the disulfide and sulfenamide type.
Effect of the Molecular Weight of Rubber on the Kinetics of Vulcanization and on the Formation of a Spatial Network
Authors: Novikov A. S. , Bartenev G. M. , Galil-Ogly F. A. 
Published: February 2011

Abstract
From scientific literature it is known that the rate of vulcanization and the mechanical properties of rubbers depend on the value of the initial molecular weight of the rubber. However, the cause of the slow vulcanization of olw molecular rubbers and the effect of the molecular weight of the rubber on the formation of a spatial network and the structure of the vulcanizate remain unclear. In the present work the kinetics of vulcanization of separate fractions of butadiene rubber SKS-30A of molecular weight from 100,000 to 1,170,000 was studied by measurements of the equilibrium modulus and the proportion of combined sulfur. The SKS-30A rubber was divided into five fractions of molecular weights: I 1,170,000; II 700,000; III 500,000; IV 140,000; and V 100,000. The molecular weights were calculated from viscometric data according to the formula previously established for this rubber by the authors: [η]=2.96×10−4 M0.71. In order to keep the molecular weight of the rubber constant, sheets for vulcanization were prepared from a dispersion of the ingredients in a benzene-rubber solution. The composition of the mixture was the same for all the fractions, i.e., 100 parts by weight of rubber, 3 parts of sulfur, 1 part of mercapto-benzothiazole, 5 parts of zinc oxide, 2 parts of stearic acid, and 1 part of phenyl-β-naphthylamine. The sheets were vulcanized in a hydraulic press at 143° C for various periods. The amount of sulfur combined with the rubber was determined by Bolotnikov's method, specially adapted to small batches of vulcanizate. The rubber specimens, weighing 0.2–0.3 gram, were extracted in 50 cc. of sodium sulfide, and titrated with 0.01N iodine solution.
Dependence of the Fundamental Properties of Unvulcanized and Vulcanized Butadiene-Styrene Rubber Mixtures on the Initial Molecular Weight
Authors: Novikov A. S. , Khaikina M. B. , Dorokhina T. V. , Arkhangelskaya M. I. 
Published: February 2011

Abstract
1. The relation of the basic properties of unvulcanized and vulcanized SKS-30A rubber-carbon black mixtures to the initial molecular weight of the rubber was studied. 2. Fractions having molecular weights up to 300,000 possess the best technical properties in their behavior during mill mixing. However, the best dispersion of carbon black is found in the still higher molecular fractions. 3. In the mill mixing of rubber with carbon black, it is principally the highest molecular fractions of the rubber which become bound, with the formation of an insoluble carbon black-rubber gel. It is shown that the thermoplastic properties of rubber-carbon black mixtures depend basically on the molecular weight and, probably, on the structure and quantity of carbon black-rubber gel formed. 4. The basic properties of vulcanizates, viz., tensile strength, relative elongation, heat resistance, and resistance to repeated deformations increase with increase of the molecular weight up to 300,000, but change little with further increase of the molecular weight. 5. The greatest reduction of the properties of vulcanizates is observed at a molecular weight of 80,000 and lower. Addition of a low-molecular fraction to a high-molecular fraction in the proportion of 1:1 greatly decreases the tensile strength and resistance to repeated deformation. 6. The range of molecular weights from 100,000 to 300,000 is, for SKS-30A rubber, the most satisfactory from the viewpoint of obtaining, throughout this range, satisfactory technical properties of mixtures before vulcanization and physical and mechanical properties after vulcanization. 7. The relation which has been established of the basic properties of a vulcanizate to its molecular weight is explained: (1) by the formation of a more regularly constructed network in a vulcanizate of the high-molecular fractions of rubber, which is distinguished from that of the low-molecular fractions by a smaller number of terminal groups not entering into the chain ; and (2) by the different nature of the reaction between carbon black and the high-molecular fractions, resulting in the latter case in a higher value of the energy of inter-molecular reaction.
The Microstructure of Diene Polymers. II. Polyisoprenes and Polybutadienes Prepared at High Pressures
Authors: Richardson W. S. 
Published: February 2011

Abstract
The rapid bulk polymerization of isoprene at room temperature under high hydrostatic pressure was apparently first observed by Bridgman and Conant. A more extensive investigation by Conant and Tongberg established the free radical nature of the polymerization (peroxide catalysis and hydroquinone inhibition). The latter workers also noted the solubility and elasticity of polymers made to moderate conversion and the insoluble crumbly nature (gelation) of the polymers made to very high conversion. In view of the well known effect of increased pressure in driving chemical reactions in the direction of the products of least specific volume, it is of interest to consider the possibility that diene polymers made at high pressures may be different in microstructure from polymers made at comparable temperatures but near atmospheric pressure.
The Effect of Masterbatching, Compounding, and Testing Variables on Constant-Slip Abrasion Results
Authors: Howland L. H. , White W. W. , Messer W. E. 
Published: February 2011

Abstract
A study of factors which affect the results obtained with the constant slip abrader in evaluation of abrasion resistance properties of GR-S vulcanizates has revealed the following : 1. As might be expected, abrasion losses decrease with increase in 300 per cent modulus. 2. Losses increase approximately logarithmically as the amount of slip between the test and abrasive wheels increases. 3. The abrasion losses decrease with increase in talcing rate, due to “lubrication” of the abrasive wheel by the talc as long as the rate is sufficient to keep the wheel free of loose abraded material. 4. Indications are that abrasion losses may increase with increase of coefficients of friction of test wheels against the abrasion wheel. 5. In a study of the effect of ambient temperature on constant slip abrasion losses, the losses increased as the temperature was raised from −10 to 30° C for GR-S 1500, GR-S 1503, and for high Mooney-viscosity GR-S 1500 extended with a naphthenic extender oil, and the losses remained essentially constant for the Resin-731 extended high Mooney viscosity GR-S 1500. The Resin-731 extended stock changed only slightly with temperature and, consequently, its comparative rating increased rapidly with rise of temperature. It was noted in photomicrographs of the wheel surfaces that the abrasion pattern which was evident at normal temperatures was absent or at best poorly defined at the lower temperatures, indicating a possible difference in kind of abrasion at low temperatures than at normal temperatures. 6. Latex masterbatches of oil and black that had been premixed by several different methods gave vulcanizates with constant-slip abrasion resistance superior to similar masterbatches prepared in the usual manner. 7. The constant-slip abrader was found to be useful in evaluating new SAF blacks and in the evaluation of the effect of using dispersing agents in carbon black and extender-carbon black masterbatching by the latex procedure.
Air Permeability of Elastomers by Diffusion Tests
Authors: Czuha M. 
Published: February 2011

Abstract
The permeability of various tread compounds to air was measured in a modified Warburg diffusion apparatus. Measurements were made at 30° C, with air applied at 48 psi. pressure, on molded disks approximately 0.025 inch thick and an area of 12.57 sq. in. The tests were reproducible within 4 per cent on control specimens. The compounds investigated showed permeabilities intermediate between the low values for Butyl and the high values for natural rubber. The permeability decreased with increasing combined styrene contents and with a decrease of temperature of polymerization for polybutadiene and low-styrene copolymers. It was unaffected by variation over a large range in polymer Mooney viscosity, gel content, and dilute-solution viscosity. A slight and almost linear decrease of permeability was found with increases in time of cure and carbon black loading for the stocks. In terms of the 300 per cent modulus, an increase of 100 psi. was accompanied by a 2 per cent decrease in permeability. Processing oil in the polymer had only a slight effect on permeability, when compared to the effects of compositional and structural modifications. Alfin and sodium, 75/25 BD/S, copolymers showed the lowest air permeability of the tread type of compounds that were studied.
The Role of Molecular Forces in the Mechanism of Swelling of High Polymers. II. Kinetics of Swelling
Authors: Gul V. E. 
Published: February 2011

Abstract
1. The rate of swelling of high-molecular compounds is a function of the chemical nature and geometric structure of the components of the mixture. 2. In an investigation of the molecular mechanism of swelling of high polymers having highly developed spatial structures, theoretical variations of the rate of swelling with the degree of swelling and molecular characteristics of the components of the mixture were derived for cases where the limiting rate is that of three-dimensional deformation of the specimen in the swelling process, and for the case where the slowest process is the diffusion penetration of the solvent. 3. It is shown that, in both the above-mentioned cases, the rate of swelling depends essentially on the values of the specific cohesion energies of the components of the mixture.
Effect of Low-Dose Aspirin on the Course of Age-Related Macular Degeneration
Authors: Robman Liubov D. , Wolfe Rory , Woods Robyn L. , Thao Le Thi Phuong , Makeyeva Galina A. , Hodgson Lauren A. B. , Lepham Y-Anh , Jachno Kim , Phung James , Maguire Emily , Luong Henry , Trevaks Ruth E. , Ward Stephanie A. , Fitzgerald Sharyn M. , Orchard Suzanne G. , Lacaze Paul , Storey Elsdon , Abhayaratna Walter P. , Nelson Mark R. , Guymer Robyn H. , McNeil John J. 
Published: May 2024

ImportanceAge-related macular degeneration (AMD) is the leading cause of irreversible vision loss in old age. There is no proven intervention to prevent AMD and, apart from lifestyle, nutritional, and supplement advice, there is no intervention to delay its progression.ObjectiveTo determine the impact of long-term low-dose aspirin on the incidence and progression of AMD.Design, Setting and ParticipantsThe Aspirin in Reducing Events in the Elderly–AMD (ASPREE-AMD) study was an Australian-based substudy of the ASPREE trial, a multicenter, international, randomized, double-masked, placebo-clinical trial investigating the efficacy of low-dose aspirin in prolonging disability-free survival among older individuals. Retinal photography was conducted at baseline from March 2010 to January 2015, then 3 and 5 years after randomization. AMD status was determined using color retinal images and treatment records. Australian participants in ASPREE aged 70 years and older without dementia, independence-limiting physical disability, cardiovascular disease, or chronic illness limiting 5-year survival and with gradable retinal images at baseline were included. Data were analyzed from December 2022 to December 2023.InterventionsAspirin (100 mg daily, enteric coated) or placebo.Main Outcomes and MeasuresIncidence of AMD and progression from early/intermediate to late AMD. Outcomes were analyzed by modified intention-to-treat analysis.ResultsA total of 4993 participants were enrolled in this substudy. Baseline characteristics were similar between groups. At the time of sponsor-determined trial termination, retinal follow-up data were available for 3208 participants, 3171 of whom were analyzed for AMD incidence and progression, with a median (IQR) age of 73.5 (71.5-76.4) years and even sex distribution (1619 [51%] female). Median (IQR) follow-up time was 3.1 (3.0-3.5) years. Cumulative AMD incidence was 195 of 1004 (19.4%) in the aspirin group and 187 of 979 (19.1%) in the placebo group (relative risk [RR], 1.02; 95% CI, 0.85-1.22; P = .86). Cumulative progression from early/intermediate AMD to late AMD was observed in 14 of 615 (2.3%) participants in the aspirin group and 18 of 573 (3.1%) in the placebo group (RR, 0.72; 95% CI, 0.36-1.44; P = .36).Conclusions and RelevanceIn this trial, low-dose aspirin administered for 3 years did not affect the incidence of AMD. The evidence was weaker for progression of AMD due to low number of progressed cases. Overall, these results do not support suggestion that low-dose daily aspirin prevents the development or progression of AMD.Trial Registrationanzctr.org Identifier: ACTRN12613000755730
Accuracy of Salivary Circulating Tumor Human Papillomavirus DNA in Detecting Oropharyngeal Cancer
Authors: Lakshmipathy Deepak , Prasad Aman , Fritz Christian G. , Go Beatrice C. , Rajasekaran Karthik 
Published: May 2024

ImportanceCirculating tumor human papillomavirus DNA (ctHPV DNA) has shown potential as a biomarker capable of improving outcomes in patients with HPV-related oropharyngeal (OP) cancer. It can be isolated from plasma or saliva, with the latter offering reduced invasiveness and theoretic reduction of lead time.ObjectiveTo perform a systematic review and meta-analysis on the accuracy of salivary ctHPV DNA for detecting HPV-associated OP cancer.Data SourcesCochrane Library, Embase, PubMed, and Web of Science databases were searched from inception through October 2023.Study SelectionAll patients who underwent salivary ctHPV DNA testing at presentation for possible or diagnosed HPV-related OP cancer were included. Non-English and review publications were excluded. Two authors independently voted on article inclusion with a third resolving conflicting votes.Data Extraction and SynthesisFollowing Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines, multiple authors independently abstracted data and assessed bias of included articles. Bivariate random-effects meta-analysis was performed with I2 to assess for study heterogeneity.Main Outcomes and MeasuresSensitivities, specificities, positive likelihood ratios (PLR), negative likelihood ratios (NLR), and diagnostic odds ratios (DOR) with 95% CIs alongside area under the curve (AUC) of a summary receiver operating characteristic (SROC) curve were calculated. The initial analysis took place throughout December 2023.ResultsOf 440 initially identified articles, 6 met inclusion criteria and demonstrated moderate heterogeneity (I2 = 36%) with low risk of bias and low applicability concerns. Overall, 263 total patients were included with a median (range) age of 58 (39-86) years, and 228 (87%) were male patients. Per updated prognostic staging criteria, localized tumors (ie, stages 1 or 2) comprised most cancers at 139 (77%), whereas advanced ones (ie, stages 3 or 4) comprised the remaining 41 (23%). Pooled sensitivity, specificity, PLR, NLR, and DOR values were 64% (95% CI, 36%-85%), 89% (95% CI, 46%-99%), 11.70 (95% CI, 0.37-77.00), 1.21 (95% CI, 0.08-7.00), and 139.00 (95% CI, 0.05-837.00), respectively. The AUC of the SROC curve was 0.80.Conclusions and RelevanceThis study supports salivary ctHPV DNA as an acceptably specific test in detecting HPV-associated OP cancer that would benefit from testing in clinical trials prior to real-time implementation.
Relative cost of ginning cotton using saw, conventional roller, and high‐speed roller gins in the United States
Authors: Acharya Ram N. , Sapkota Sushil C. , Bhandari Pratima , Armijo Carlos , Whitelock Derek 
Published: May 2024

AbstractThe primary objective of this study was to investigate whether the cost of processing cotton using high‐speed roller gins is comparable to saw gins. The results from a “true” random effect model estimated using proprietary data voluntarily shared by cotton gins operating in Arizona and California showed that the average cost inefficiency for the sample gins analyzed in this study was 13.5%. Moreover, the cost of ginning using conventional roller gins and high‐speed roller gins was 24.42% and 14.18% higher than saw gins, respectively, and roller ginning costs were 10% lower for high‐speed roller gins than conventional roller gins. [EconLit Citations: D24; O14; Q16].
Anomalous Structural Transformation of Cu(I) Clusters into Multifunctional CuAg Nanoclusters
Authors: Yao Yuqing , Hao Wei , Tang Jin , Kirschbaum Kristin , Gianopoulos Christopher G. , Ren An , Ma Liang , Zheng Letian , Li Hanying , Li Qi 
Published: May 2024

AbstractWe report an anomalous structural transformation of a Cu(I) cluster into two different types of copper‐silver (CuAg) alloy nanoclusters. Different from previous reports, we demonstrate that under specifically designed reaction conditions, the Ag‐doping could induce a substantial growth of the starting Cu15 and a Ag13Cu20 nanocluster was obtained via the unexpected insertion of an Ag13 kernel inside the Cu(I)‐S shell. Ag13Cu20 demonstrates high activity to initiate the photopolymerization of previously hard‐to‐print inorganic polymers in 3D laser microprinting. Interestingly, a slight modification of the reaction condition leads to the formation of another Ag18‐xCuxS (8≤x) nanocluster templated by a central S2− anion, which possesses a unique electronic structure compared to conventional template‐free CuAg nanoclusters. Overall, this work unveils the intriguing doping chemistry of Cu clusters, as well as their capability to create different types of alloy nanoclusters with previously unobtainable structures and multifunctionality.
Redox Engineering of Myoglobin by Cofactor Substitution to Enhance Cyclopropanation Reactivity
Authors: Kagawa Yoshiyuki , Oohora Koji , Himiyama Tomoki , Suzuki Akihiro , Hayashi Takashi 
Published: May 2024

AbstractDesign of metal cofactor ligands is essential for controlling the reactivity of metalloenzymes. We investigated a carbene transfer reaction catalyzed by myoglobins containing iron porphyrin cofactors with one and two trifluoromethyl groups at peripheral sites (FePorCF3 and FePor(CF3)2, respectively), native heme and iron porphycene (FePc). These four myoglobins show a wide range of Fe(II)/Fe(III) redox potentials in the protein of +147 mV, +87 mV, +42 mV and −198 mV vs. NHE, respectively. Myoglobin reconstituted with FePor(CF3)2 has a more positive potential, which enhances the reactivity of a carbene intermediate with alkenes, and demonstrates superior cyclopropanation of inert alkenes, such as aliphatic and internal alkenes. In contrast, engineered myoglobin reconstituted with FePc has a more negative redox potential, which accelerates the formation of the intermediate, but has low reactivity for inert alkenes. Mechanistic studies indicate that myoglobin with FePor(CF3)2 generates an undetectable active intermediate with a radical character. In contrast, this reaction catalyzed by myoglobin with FePc includes a detectable iron–carbene species with electrophilic character. This finding highlights the importance of redox‐focused design of the iron porphyrinoid cofactor in hemoproteins to tune the reactivity of the carbene transfer reaction.