bluuebunny/crossref_metadata_2025 huggingface dataset:
Satisfying End User Constraints in Service Composition by Applying Stochastic Search Methods
Authors: Lecue Freddy , Mehandjiev Nikolay
Published: February 2011

Semantic web service compositions must be aligned with requirements from the target users in terms of quality requirements. Given a set of quality requirements, one can choose to either find the optimal composition or a “good enough” composition, which satisfies these requirements. Since optimizing compositions of semantic services under quality constraints is known to be NP-hard, it is unsuitable for realistic problems within large search spaces. The authors address the issue by using the “good enough” approach, selecting the first composition that passes their quality threshold. Firstly, this paper defines quality constraints within an innovative and extensible model designed to balance semantic fit (or functional quality) with quality of service (QoS) metrics. The semantic fit criterion evaluates the quality of semantic links between the semantic descriptions of Web services parameters, while QoS focuses on non-functional criteria of services. User quality requirements are met by selecting a valid composition. To allow the use of this model with a large number of candidate services as foreseen by the strategic EC-funded project SOA4All the authors formulate the selection problem as a Constraint Satisfaction Problem and test the use of a stochastic search method.
Mediation Spaces for Similarity-Based Semantic Web Services Selection
Authors: Dietze Stefan , Gugliotta Alessio , Domingue John , Mrissa Michael
Published: February 2011

Semantic Web Services (SWS) aim at the automated discovery, selection and orchestration of Web services based on comprehensive, machine-interpretable semantic descriptions. The latter are, in principle, deployed by multiple possible actors (i.e., service providers and service consumers); thus, a high level of heterogeneity between distinct SWS annotations is expected. Therefore, mediation between concurrent semantic representations of services is a key requirement to fully implement the SWS vision. In this paper, the authors argue that “semantic-level mediation” is necessary to identify semantic similarities across distinct SWS representations. The authors formalize and implement a mediation approach based on “Mediation Spaces” (MS), which enables the implicit representation of semantic similarities among distinct SWS descriptions. As a result, given a specific SWS approach and the proposed MS, a general purpose algorithm is implemented to empower SWS selection with the automatic computation of semantic similarities between a given SWS request and a set of SWS offers. A prototypical application illustrates the approach and highlights the benefits w.r.t. current mediation approaches.
A Polymorphism in the Coding Region ofIl12bPromotes IL-12p70 and IL-23 Heterodimer Formation
Authors: Zwiers Antonie , Fuss Ivan J. , Seegers Diana , Konijn Tanja , Garcia-Vallejo Juan J. , Samsom Janneke N. , Strober Warren , Kraal Georg , Bouma Gerd
Published: February 2011

IL-12 and IL-23 are heterodimeric cytokines involved in the induction of Th1 and Th17 immune responses. Previous work indicated that a region on chromosome 11 encoding the IL-12p40 subunit regulates strain differences in susceptibility to murine trinitrobenzene sulfonic acid-induced colitis. In addition, this region determines strain differences in LPS-induced IL-12 responses. In this study, we investigated how polymorphisms in the coding region of murine Il12b influence IL-12 and IL-23 heterodimer formation. Transfection studies using constructs containing IL-12p35 linked to IL-12p40 from the colitis-resistant C57BL/6 strain or to the polymorphic p40 variant from the colitis-susceptible SJL/J strain demonstrated that SJL/J-derived p40 constructs synthesized significantly more IL-12p70 than did constructs harboring the C57BL/6-p40 variant. This could not be attributed to differences in synthesis rate or secretion, implicating a greater affinity of SJL/J-derived IL-12p40 for its IL-12p35 subunit. This greater affinity is also associated with increased IL-23 synthesis. In addition, C57BL/6 mice transgenic for the SJL/J 40 variant synthesized significantly more IL-12p70 upon LPS challenge and were more prone to develop colonic inflammation than did C57BL/6 mice transgenic for the C57BL/6-p40 variant. The more efficient binding of the polymorphic Il12b variant to p35 and p19 is most likely due to conformational changes following differential glycosylation as a consequence of the polymorphism. The high synthesis rate of the mature cytokines resulting from this efficient binding can lead to rapid proinflammatory skewing of immune responses and distortion of the homeostatic balance underlying the greater susceptibility for colitis.
TCR Bias of In Vivo Expanded T Cells in Pancreatic Islets and Spleen at the Onset in Human Type 1 Diabetes
Authors: Codina-Busqueta Eva , Scholz Erika , Muñoz-Torres Pau M. , Roura-Mir Carme , Costa Manuela , Xufré Cristina , Planas Raquel , Vives-Pi Marta , Jaraquemada Dolores , Martí Mercè
Published: February 2011

Autoreactive T cells, responsible for the destruction of pancreatic β cells in type 1 diabetes, are known to have a skewed TCR repertoire in the NOD mouse. To define the autoreactive T cell repertoire in human diabetes, we searched for intraislet monoclonal expansions from a recent onset in human pancreas to then trace them down to the patient’s peripheral blood and spleen. Islet infiltration was diverse, but five monoclonal TCR β-chain variable expansions were detected for Vβ1, Vβ7, Vβ11, Vβ17, and Vβ22 families. To identify any sequence bias in the TCRs from intrapancreatic T cells, we analyzed 139 different CDR3 sequences. We observed amino acid preferences in the NDN region that suggested a skewed TCR repertoire within infiltrating T cells. The monoclonal expanded TCR sequences contained amino acid combinations that fit the observed bias. Using these CDR3 sequences as a marker, we traced some of these expansions in the spleen. There, we identified a Vβ22 monoclonal expansion with identical CDR3 sequence to that found in the islets within a polyclonal TCR β-chain variable repertoire. The same Vβ22 TCR was detected in the patient’s PBMCs, making a cross talk between the pancreas and spleen that was reflected in peripheral blood evident. No other pancreatic monoclonal expansions were found in peripheral blood or the spleen, suggesting that the Vβ22 clone may have expanded or accumulated in situ by an autoantigen present in both the spleen and pancreas. Thus, the patient’s spleen might be contributing to disease perpetuation by expanding or retaining some autoreactive T cells.
Ocular Neovascularization Caused by Herpes Simplex Virus Type 1 Infection Results from Breakdown of Binding between Vascular Endothelial Growth Factor A and Its Soluble Receptor
Authors: Suryawanshi Amol , Mulik Sachin , Sharma Shalini , Reddy Pradeep B. J. , Sehrawat Sharvan , Rouse Barry T.
Published: February 2011

The normal cornea is transparent, which is essential for normal vision, and although the angiogenic factor vascular endothelial growth factor A (VEGF-A) is present in the cornea, its angiogenic activity is impeded by being bound to a soluble form of the VEGF receptor-1 (sVR-1). This report investigates the effect on the balance between VEGF-A and sVR-1 that occurs after ocular infection with HSV, which causes prominent neovascularization, an essential step in the pathogenesis of the vision-impairing lesion, stromal keratitis. We demonstrate that HSV-1 infection causes increased production of VEGF-A but reduces sVR-1 levels, resulting in an imbalance of VEGF-A and sVR-1 levels in ocular tissues. Moreover, the sVR-1 protein made was degraded by the metalloproteinase (MMP) enzymes MMP-2, -7, and -9 produced by infiltrating inflammatory cells that were principally neutrophils. Inhibition of neutrophils, inhibition of sVR-1 breakdown with the MMP inhibitor marimastat, and the provision of exogenous recombinant sVR-1 protein all resulted in reduced angiogenesis. Our results make the novel observation that ocular neovascularization resulting from HSV infection involves a change in the balance between VEGF-A and its soluble inhibitory receptor. Future therapies aimed to increase the production and activity of sVR-1 protein could benefit the management of stromal keratitis, an important cause of human blindness.
A Meningococcal Factor H Binding Protein Mutant That Eliminates Factor H Binding Enhances Protective Antibody Responses to Vaccination
Authors: Beernink Peter T. , Shaughnessy Jutamas , Braga Emily M. , Liu Qin , Rice Peter A. , Ram Sanjay , Granoff Dan M.
Published: February 2011

Certain pathogens recruit host complement inhibitors such as factor H (fH) to evade the immune system. Microbial complement inhibitor-binding molecules can be promising vaccine targets by eliciting Abs that neutralize this microbial defense mechanism. One such Ag, meningococcal factor H-binding protein (fHbp), was used in clinical trials before the protein was discovered to bind fH. The potential effect of fH binding on vaccine immunogenicity had not been assessed in experimental animals because fHbp binds human fH specifically. In this study, we developed a human fH transgenic mouse model. Transgenic mice immunized with fHbp vaccine had 4- to 8-fold lower serum bactericidal Ab responses than those of control mice whose native fH did not bind the vaccine. In contrast, Ab responses were unimpaired in transgenic mice immunized with a control meningococcal group C polysaccharide–protein conjugate vaccine. In transgenic mice, immunization with an fH nonbinding mutant of fHbp elicited Abs with higher bactericidal activity than that of fHbp vaccination itself. Abs elicited by the mutant fHbp more effectively blocked fH binding to wild-type fHbp than Abs elicited by fHbp that bound fH. Thus, a mutant fHbp vaccine that does not bind fH but that retains immunogenicity is predicted to be superior in humans to an fHbp vaccine that binds human fH. In the case of mutant fHbp vaccination, the resultant Ab responses may be directed more at epitopes in or near the fH binding site, which result in greater complement-mediated serum bactericidal activity; these epitopes may be obscured when human fH is bound to the wild-type fHbp vaccine.
Cutting Edge: Mast Cells Regulate Disease Severity in a Relapsing–Remitting Model of Multiple Sclerosis
Authors: Sayed Blayne A. , Walker Margaret E. , Brown Melissa A.
Published: February 2011

Mast cells (MCs) exert a significant pathologic influence on disease severity in C57BL/6 (B6) strain-dependent experimental allergic encephalomyelitis (EAE), a model of primary progressive multiple sclerosis (MS). However, relapsing–remitting MS, which is modeled in SJL mice, is the more prevalent form. Given genetically determined heterogeneity in numbers and responsiveness of MCs from various strains of mice, we asked whether these cells also influence this more clinically relevant MS model using SJL-KitW/W-v mice. Similar to the commercially available WBB6F1-KitW/W-v mice, SJL-KitW/W-v mice are MC-deficient, anemic, and neutropenic and have normal T cell compartments. They exhibit significantly reduced disease severity, but retain the relapsing–remitting course, a phenotype reversed by selective MC reconstitution. These data confirm that MC influence is not confined to an isolated model of EAE and reveal a new system to study the effects of MC heterogeneity on relapsing–remitting EAE and other SJL strain-specific diseases.
The Role of the Mitochondrial Genome in Ageing and Carcinogenesis
Authors: Czarnecka Anna M. , Bartnik Ewa
Published: February 2011

Mitochondrial DNA mutations and polymorphisms have been the focus of intensive investigations for well over a decade in an attempt to understand how they affect fundamental processes such as cancer and aging. Initial interest in mutations occurring in mitochondrial DNA of cancer cells diminished when most were found to be the same mutations which occurred during the evolution of human mitochondrial haplogroups. However, increasingly correlations are being found between various mitochondrial haplogroups and susceptibility to cancer or diseases in some cases and successful aging in others.
A severe case of tetracycline-induced intracranial hypertension
Authors: Holst Anders Vedel , Danielsen Patricia Louise , Romner Bertil
Published: February 2011

Tetracykline is a first-line treatment of the common skin disorder acne vulgaris. A rare side effect of tetracycline treatment is intracranial hypertension also called pseudotumor cerebri (PTC). We report a severe case of PTC with cranial nerve palsy and visual loss in a 16 year old girl following acne vulgaris treatment with tetracycline.
Excess granulation tissue and hair loss following acitretin
Authors: Gaudiello Francesca , Scalvenzi Massimiliano , Gallo Lucia , Balato Nicola
Published: February 2011

Retinoids are routinely used in dermatology for various clinical entities including acne vulgaris, rosacea, hypertrophic scars, strie distensae, psoriasis, disorders of dyskeratinization, cancer prevention and other chronic hyperkeratotic disorders. Oral acitretin therapy is effective in the treatment of psoriasis normalizing cellular differentiation and maturation but clinical side-effects are reported. We describe the occurrence of excess granulation tissue in the nails sulcus and noncicatricial universal alopecia in a psoriatic patient receiving oral acitretin.
Clinical Case of Acute Myeloblastic Leukemia with t(8;21)(q22;q22) in a Patient with Klinefelter’s Syndrome
Authors: Slavcheva Vanya , Lukanov Tzvetan , Balatsenko Gueorgui , Angelova Svetlana , Antonov Antonio , Bogdanov Lachezar , Tsvetkov Nikolay
Published: February 2011

Klinefelter’s syndrome is characterized by abnormal karyotype 47, XXY and a phenotype associated with hypogonadism and gynecomastia. Often the disease can be diagnosed accidentally, when carrying out cytogenetic analysis in cases of a malignant blood disease. We present the clinical case of a patient diagnosed with acute myelomonoblastic leukemia- M4 Eo (AML- M4), where by means of classic cytogenetics a karyotype was found corre-sponding to Klinefelter’s syndrome. Three induction courses of polychemotherapy wermade, which led to remission of the disease, documented both flowcytometrically and cytogenetically.
Treatment Relapsed Subcutaneous Panniculitis-like T-Cell Lymphoma together HPS by Cyclosporin A
Authors: Chen Ren'an , Liu Li , Liang Yinmin
Published: February 2011

A 25-year-old man was diagnosised subcutaneous panniculitis-like T-cell lymphoma (SPTCL) through biopsy of a nodule from the anterior chest. After the treatment with prednisone 90 mg 3 weeks and tapered off in 1 month, the disease released, but relapsed together with symptions of hemophagocytic syndrome eight months after the termination of prednisone. CHOEP recipe was given but with unsatisfactory result until cyclosporine was prescribed. Cyclosporine was removed 6 months later. There is no evidence of clinical relapse 1 year later. This case suggest that cyclosporine could be a selectable treatment even in relapsed SPTCL.
Geology, Precambrian geology of northern Boothia Peninsula and Somerset Island, Nunavut
Authors: Frisch T
Published: February 2011

The map area lies in the central part of the Boothia Uplift, a linear, positive structural feature extending northward more than 900 km from southern Boothia Peninsula through Somerset Island to the central Arctic Archipelago. The southern two-thirds of the
uplift comprises a crystalline core (a salient of the Precambrian Shield) and flanking unmetamorphosed, Proterozoic to Devonian sedimentary strata. The salient is bordered on the west (Prince of Wales Island) by a Silurian-Devonian clastic wedge. Uplift largely occurred along steeply east-dipping
thrust faults during the Siluro-Devonian, the movement possibly being related to Caledonian orogeny far to the east (Okulitch et al., 1986). The crystalline core between 71° and 74°N, some 80 km wide and consisting of high-grade metamorphic rocks of the Churchill Structural Province, was
the focus of the mapping project.
In silico Analysis of Combinatorial microRNA Activity Reveals Target Genes and Pathways Associated with Breast Cancer Metastasis
Authors: Dombkowski Alan A. , Sultana Zakia , Craig Douglas B. , Jamil Hasan
Published: February 2011

Aberrant microRNA activity has been reported in many diseases, and studies often find numerous microRNAs concurrently dysregulated. Most target genes have binding sites for multiple microRNAs, and mounting evidence indicates that it is important to consider their combinatorial effect on target gene repression. A recent study associated the coincident loss of expression of six microRNAs with metastatic potential in breast cancer. Here, we used a new computational method, miR-AT!, to investigate combinatorial activity among this group of microRNAs. We found that the set of transcripts having multiple target sites for these microRNAs was significantly enriched with genes involved in cellular processes commonly perturbed in metastatic tumors: cell cycle regulation, cytoskeleton organization, and cell adhesion. Network analysis revealed numerous target genes upstream of cyclin D1 and c-Myc, indicating that the collective loss of the six microRNAs may have a focal effect on these two key regulatory nodes. A number of genes previously implicated in cancer metastasis are among the predicted combinatorial targets, including TGFB1, ARPC3, and RANKL. In summary, our analysis reveals extensive combinatorial interactions that have notable implications for their potential role in breast cancer metastasis and in therapeutic development.
Sub-unit Specific Regulation of Type-A GABAergic Receptors during Post-Natal Development of the Auditory Cortex
Authors: Tremere Liisa A.
Published: February 2011

The GABA-A receptor has been strongly implicated in the organization and function of cortical sensory circuits in the adult mammal. In the present work, changes in the expression patterns of select GABA-A subunits were examined as a function of development. The RNA expression profiles for three subunit types were studied, α1, β2/3 and δ at four developmental time points, (p0, p15, p30 and p90). The o1, β2/3 subunits were present at birth and following a modest increase early in life; mRNA expression for these subunits were found at stable levels throughout life. The expression pattern for the δ subunit showed the most dramatic changes in the number of positive cells as a function of age. In early life, p0 through p15 expression of mRNA for the δ subunit was quite low but increased in later life, p30 and p90. Together these data suggest that much of the potential for inhibitory connectivity is laid down in the pre and early post-natal periods.
H2 vertical profiles in the continental boundary layer: measurements at the Cabauw tall tower in the Netherlands
Authors: Popa M. E. , Vermeulen A. T. , van den Bulk W. C. M. , Jongejan P. A. C. , Batenburg A. M. , Zahorowski W. , Röckmann T.
Published: February 2011

Abstract. In-situ, quasi-continuous measurements of atmospheric hydrogen (H2) have been performed since 2007 at the Cabauw tall tower station in the Netherlands. Mole fractions of H2, CO and several greenhouse gases are determined simultaneously in air sampled successively at four heights, between 20 and 200 m above ground level. 222Rn measurements are performed in air sampled at 20 and 200 m. This H2 dataset represents the first in-situ, quasi-continuous measurement series of vertical profiles of H2 in the lower continental boundary layer. From the three-year long time series, we characterize the main features and variability patterns of H2 and CO on various time scales; the time series is too short to justify an attempt to determine multi-annual trends. Seasonal cycles are present in both H2 and CO, and their amplitude varies with the sampling height. The seasonality is evident in both the "baseline" values and in the short term (diurnal to synoptic time scales) variability, the latter being significantly larger during winter. The observed H2 short term signals and vertical gradients are in many cases well correlated to other species, especially to CO. On the other hand, H2 has at times a behaviour which differentiates it from all the other species measured, due to its particular distribution of sources and sinks, that is, with the main source in our area (anthropogenic emissions) and the main sink (soil uptake) both near ground level. The local to regional soil sink of H2 is observable as H2 depletion at the lower sampling levels in some of the stable nights, although the signals at Cabauw are smaller than observed at other stations. Positive vertical gradients are another consequence of the soil uptake. Our estimation for the regional H2 soil uptake flux, using the radon tracer method, is (−1.89 ± 0.26) × 10−5 g/(m2h), significantly smaller than other recent results from Europe. Local soil and weather characteristics might be responsible for the very low soil uptake of H2. Our result could also be biased by the absence of radon flux estimates that could reliably approximate the fluxes during the relevant time intervals in our study domain. H2/CO ratios of the traffic emissions computed from our data, with an average of 0.54 ± 0.07 mol:mol, are larger and more scattered than estimated in some of the previous studies in Europe. This difference can be explained by a different driving regime, due to the frequent traffic jams in the influence area of Cabauw. In contrast, the H2/CO ratios of the large scale pollution events, with an average of 0.36 ± 0.05 mol:mol, are very similar to results of previous studies; these ratios were observed to slightly increase with sampling height, possibly due to a stronger influence of soil uptake at the lower sampling heights.
Multiple magnetic dipolarizations observed by THEMIS during a substorm
Authors: Duan S. P. , Liu Z. X. , Liang J. , Zhang Y. C. , Chen T.
Published: February 2011

Abstract. The magnetic field dipolarization in the vicinity of substorm onset and during substorm expansion phase during the period of 06:00–06:40 UT on 15 February 2008 is investigated with observations from multiple probes of THEMIS. It is found that the magnetic dipolarization at the substorm onset (the onset time was about 06:14 UT) was not accompanied by obvious magnetic disturbance and ion bulk speed variation. The magnetic dipolarizations taking place during the substorm expansion phase observed by P4~(−10.97, 2.04, −3.03) RE and P3~(−11.32, 1.15, −3.10) RE were mostly accompanied by high speed earthward ion bulk flow, but the magnetic dipolarizations occurring during the substorm expansion phase observed by P5~(−9.45, 1.07, −2.85) RE were not accompanied by high speed earthward ion bulk flow. Before substorm onset THEMIS P3, P4, P5 all observed the Bx component fluctuation with a period of about 300 s. After substorm onset earthward high speed ion bulk flow and significant magnetic disturbances both occurred at P3 and P4 locations. These results indicate that there is no one-to-one relationship between the near-Earth magnetic dipolarization and the earthward ion bulk flow. In particular, the magnetic dipolarization occurring on the earthward side of the inner near-Earth plasma sheet is not accompanied by high speed earthward ion bulk flow. The dipolarization at substorm onset is a local and small scale phenomenon. There are multiple magnetic dipolarizations occurring during the substorm expansion phase. The dipolarization process is very complex and is not simply an MHD process. It is accompanied by some kinds of plasma instabilities, the plasma sheet azimuthal expansion not only by earthward ion bulk flow during substorm. A sharp increase of the AE index does not always give an accurate substorm onset time for substorm analysis.
Fate of patients treated in emergency department non-hospital
Authors: Pedreira Larissa Chaves , Reis Virginia Ramos dos Santos Souza , Oliveira Yara Santos
Published: February 2011

ABSTRACTObjective: to identify the fate of critically ill patients admitted to a hospital unit is not an emergency. Method: this is a quantitative study documentary and retrospective. Results: among the patients involved in the study, 41.01% and 30.12% were defined in the same destination or the next date, respectively. The output of the unit was 68.1% with high medical, transferred 24.56% and 3.79% died. Final considerations: patients with high complexity remained for long periods, does not respect the hierarchy of the system and the unit meets the specification of the legislation that regulates acute resolving less complex and assisting the patient more complex to define the destination. Descriptors: nursing; emergency nursing; emergency medical Services; emergency reatment; prehospital care ; critical care; health policy.RESUMOObjetivo: identificar o destino dos pacientes graves admitidos numa unidade não hospitalar de emergência. Método: trata-se de um estudo documental quantitativo e retrospectivo. Resultados: dentre os pacientes relacionados no estudo, 41,01% e 30,12% obtiveram destino definido na mesma ou na data seguinte, respectivamente. A saída da unidade ocorreu 68,1% através de alta médica, 24,56% transferidos e 3,79% evoluíram para óbito. Considerações finais: pacientes de alta complexidade permaneceram por períodos longos, não respeitando a hierarquização do sistema, assim a unidade atende a especificação da legislação que a normatiza resolvendo quadros agudos de menor complexidade e assistindo o paciente de maior complexidade até a definição do destino deste. Descritores: enfermagem; enfermagem em emergência; tratamento de emergência; serviços médicos de emergência; assistência pré-hospitalar; cuidados críticos; política de saúde.RESUMENObjetivo: identificar el destino de los pacientes graves admitidos en una unidad no hospitalaria de emergencia. Métodos: estudio cuantitativo documental y retrospectivo. Resultados: los datos fueron colectados en los históricos médicos de los pacientes atendidos, obedeciendo criterios de inclusión y exclusión. Entre los pacientes relacionados, 41,01% y 30,12% obtuvieron, respectivamente, destino definido en la misma fecha o en fecha siguiente. La salida de la unidad através de alta médica fue de un 68,1%, transferidos, 24,56 % y un 3,79% evoluyeron para óbito. Consideraciones finales: pacientes de alta complejidad permanecieron por largos períodos, no respetando la jerarquización del sistema. De este modo, la unidad atiende la especificación de la legislación que la normatiza, resolviendo cuadros agudos de menor complejidad, y asistiendo al paciente de mayor complejidad hasta la definición del destino de éste. Descriptores: enfermería; enfermería de urgencia; tratamiento de urgencia;  servicios médicos de urgencia; atención prehospitalaria; cuidados intensivos; política de salud.
Sorption of GR-S Type of Polymer on Carbon Black. III. Sorption by Commercial Blacks
Authors: Kolthoff I. M. , Gutmacher R. G.
Published: February 2011

The sorption capacities toward GR-S five commercial carbon blacks are in decreasing order: Spheron-6, Vulcan-1, Philblack-0, Sterling-105, Philblack-A. Apparently, the sorption is not related to surface area. The sorption on Vulcan-1 of GR-S from its solutions in seven different solvents or mixtures of solvents increases with decreasing solvent power for the rubber. The sorption curves of two “cold rubbers,” polymerized at −10 and +5° respectively, showed little difference from that of 50° GR-S. Previous heating of carbon black in nitrogen at 500 or 1100° increased the sorption by about 20 per cent over unheated carbon. Air-heating of carbon black at 425° did not cause a difference in the sorption from benzene solution, but produced an increase in the sorption of rubber from n-heptane solution. In the range 75% butadiene-25% styrene to 5% butadiene-95% styrene, there is practically no effect of the degree of unsaturation on the sorption. Polystyrene of high intrinsic viscosity exhibits a peculiar behavior with furnace blacks. Vulcan-1 sorbed microgel as well as the sol fraction from n-heptane solutions of GR-S containing microgel (conversion 74.7 and 81.5 per cent). There was no appreciable difference in the amount of sorption of rubber fractions having average molecular weights varying from 433,000 to 85,000. There is little change in the amount sorbed after two hours of shaking, but the intrinsic viscosity of the residual rubber decreases with time. The low molecular-weight rubber is sorbed more rapidly, but is slowly replaced by the more tightly sorbed high molecular weight fraction. Partial fractionation of a rubber sample can be achieved by allowing the rubber solution to flow through a column of weakly sorbing carbon black. A large portion of the sorbed rubber can be recovered from the column by washing it with a good solvent such as xylene. Bound rubber is produced by intimate mixing of equal parts of carbon black and rubber swollen in chloroform, when the mixture is dried in vacuum at 80° or at room temperature. Milling is not essential to get bound rubber.
The Effect of Softeners in Rubber
Authors: Williams Ira
Published: February 2011

The use of oils and liquid softeners to assist in the mastication and processing of rubber or to produce softer vulcanized stocks has been standard practice since the early commercial use of rubber. More recently certain synthetic rubbers, polymerized under special conditions, have been treated with rather large amounts of mineral oils, with a resulting decrease in the cost of the rubber and apparently with no unfavorable effect on the rubber in most instances. A number of investigators have reported the effect of swelling agents on the properties of vulcanized rubber. Busse discusses the effect of solvents in a general way. Tiltman and Porritt conclude that the decrease in modulus caused by swelling in benzene is caused by a “loosening of cohesive forces.” Tire treads of natural rubber containing such softeners as pine tar and mineral rubber decrease in wear resistance in proportion to the softener content. Well vulcanized rubber of high modulus is most resistant to swelling in oils. Naunton, Jones, and Smith find that unaccelerated stocks lose the most tensile strength after being swollen, that milling of the raw rubber increases swelling, and that the presence of softeners in the rubber during vulcanization reduces the oil resistance. A limited amount of swelling has been reported to have little effect on the tensile strength of vulcanized natural rubber. Bourbon points out that separating the rubber molecules with solvent decreases the rate of vulcanization.
Abrasion Pattern on Rubber
Authors: Schallamach A.
Published: February 2011

It has been observed that an array of nearly parallel ridges is often produced by abrasion on rubber surfaces. This array is called the “abrasion pattern.” The ridges run at right angles to the direction of abrasion, and their profile is asymmetrical with respect to the direction of abrasion. Various properties of the abrasion pattern are described, and its use in the elucidation of the mode of abrasion of tires is discussed.
Quantitative Determination of Copper in Natural Rubber
Authors: Milliken Lewis T.
Published: February 2011

A procedure is recommended in which small amounts of copper in rubber can be measured quantitatively by determining the depth of color of a copper carbamate complex in a carbon tetrachloride solution. The complex is formed in an alkaline solution prepared from an acid extract of the rubber ashed at 550° C. This procedure yields results which are as reliable as those obtained by the more tedious and time-consuming procedures involving the wet-oxidation process which are at present recommended by standardizing organizations. The use of an organic solution rather than an aqueous suspension gives better reproducibility, permits easier use of a photometer, and reduces the interference due to iron by a factor of ten.
Small Amounts of Copper in Dyes and Rubber Chemicals. Colorimetric Determination with Zinc Dibenzyldithiocarbamate
Authors: Martens R. I. , Githens R. E.
Published: February 2011

This work was undertaken to provide a more specific method for the routine determination of small amounts of copper in rubber chemicals, dyes, and dyed fabrics. A dithiocarbamate type of reagent—a 0.01 per cent solution of zinc dibenzyldithiocarbamate in carbon tetrachloride—will selectively extract copper from acid solutions containing relatively large amounts of most other metals. The method is accurate and reproducible to about 0.5 microgram in the range of 0.5 to 40 micrograms of copper. No precipitations or filtrations are required. The reagent is commercially available, the reagent solution and the color of the extracted copper dibenzyldithiocarbamate are stable, and the acid solution remaining after extraction may be used to determine other metals. Because copper dibenzyldithiocarbamate is selectively extracted from solutions containing relatively large amounts of many other metallic ions, the reagent may be used to determine small amounts of copper in metals and their salts.
The Effect of Elongation on the Time of Relaxation T2 of Natural Rubber
Authors: Cohen-Hadria Armand , Gabillard Robert
Published: February 2011

An experimental study, first, of the relaxation time T2 of natural rubber as a function of temperature and, in turn, of the influence of elongation on these changes of T2 has proved that, within the temperature range of −15° and 5° C, the gradient ΔT2/Δθ of the T2=ƒ(θ) curve decreases in proportion to the elongation.
Investigation of Fractionated Polybutadienes by a Dynamic-Optical Method
Authors: Tzvetkov V. N. , Petrova A. I. , Poddubny I. Y.
Published: February 2011

Data obtained by a study of the dynamic-optical double refraction of solutions of various fractions of polybutadienes which had been prepared at various polymerization temperatures are presented. The relation between double refraction and the rate gradient generally has the form of a curve. However, the halos and the sign of the curvature vary for the same sample in different solvents, as well as for samples polymerized at different temperatures in the same solvent, and the time of deformation relaxation of the macromolecules of polymer in solution is measured by the curvature of these curves. On the basis of these data, conclusions are drawn regarding the shape of the macromolecules in various solvents and the influence of the temperature of polymerization on the configuration of the molecules.
Chromatography of Rubber Accelerators and Antioxidants on Silica Gel
Authors: Parker C. A.
Published: February 2011

The Chromatographic separation on alumina columns of certain components from the acetone extracts of vulcanized rubbers has been reported by Bellamy and coworkers and by Mann. As an adsorbent for such materials, alumina suffers from certain disadvantages, in particular, its tendency to favor chemical change in labile adsorbates. The successful use of silica gel/Celite for the chromatographic separation of a variety of ingredients from propellants and high explosives' suggested that this adsorbent might prove equally useful for the separation of the ingredients of vulcanized rubbers, and this has, in fact, been borne out by recent work in this laboratory. The procedure adopted for the qualitative examination of a rubber extract is as follows. A number of separate portions of the extract (each equivalent to 0.2–0.4 gram of the rubber) are chromatographed on columns of 1 cm. diameter, using a series of different binary solvent mixtures as developers. When the extruded columns have been streaked with appropriate reagents, the positions of the zones, together with the colors of the streaks, give a reasonably unambiguous identification, which can be further confirmed by ultraviolet absorption measurements.
Preparing Crude Rubber Test-Specimens for Oxygen-Absorption Measurements
Authors: Gowans William J.
Published: February 2011

Recent investigations have shown the advantages of using a volumetric oxygen-absorption apparatus for accelerated aging tests on crude rubber. Current work in this laboratory has confirmed the advantages of this apparatus as a rapid means for determining the storage stability of a given crude rubber stock. Unfortunately, crude rubber test-specimens cannot be placed in the oxygen-absorption apparatus in the same manner as can test-specimens of vulcanizates. The tendency of crude rubber to flow, particularly during the more advanced stages of oxidation, may cause errors in oxygen-absorption measurements by limiting the diffusion of oxygen into the test-specimen. For this reason it was necessary to devise a method of preparing rubber test-specimens for oxygen-absorption measurements which is applicable to crude rubber. Test-specimens of crude rubber suitable for oxygen-absorption measurements can be readily prepared with the aid of an aluminum mold and a vulcanizing press. The method of pressing the crude rubber into a sheet from which the specimens are taken is a slight modification of that used by McPherson and Cummings in preparing samples for refractive-index measurements. Oxygen-absorption data were obtained in an apparatus similar to the one described by Shelton and Winn'. The results indicate several important advantages of the present hot-press method of sample preparation, compared with the test tube-film method used by Glazer and coworkers in preparing crude GR-S samples for oxygen-absorption studies.
Products of Oxidation of an Olefin Structurally Related to GR-S
Authors: Mitchell G. R. , Shelton J. Reid
Published: February 2011

The fields of rubber, plastics, surface coatings, and petroleum include a considerable portion of the industrial activity of the world, and in each of these industries oxidation is an important factor in product processing and in the properties of the final product. Information regarding the nature of the oxidation reactions observed in any of these fields can be applied in part to the others. Because of the complexity of the materials involved, it is frequently desirable to study pattern molecules of comparable structure and to seek to apply the knowledge obtained in this way to the more complex systems. This investigation is a part of a research program on the nature of the oxidation of natural and synthetic rubber and related materials. It is confined to the study of an olefin, 5-phenyl-2-pentene, which represents one of the possible repeating structural units of GR-S rubber. There is considerable information in the literature regarding the probable mechanism of oxidation of hydrocarbons, both saturated and unsaturated. The oxidation of olefins, for example, has been studied extensively by workers in the laboratory of the British Rubber Producers' Research Association and the following sequence of reactions for either thermal or photoxidation with molecular oxygen was proposed:
Polymerization and Copolymerization Reactions with Alfin Catalysts. In Relation to Masterbatch Preparation
Authors: Stewart R. A. , Williams H. Leverne
Published: February 2011

Alfin catalysts, as developed by Morton, have been used for a study of the polymerization reactions of butadiene-styrene, and other monomers. Catalyst activity was affected by minor variations in the method of preparation and increased during the first few days of storage of the catalyst. Water, alcohols, and ketones acted as catalyst poisons. Technical pentane and crude propylene streams can replace the normally pure materials used in the preparation of the catalyst. Copolymers of butadiene with styrene or α-methylstyrene were slightly richer in the styrene than the corresponding emulsion copolymers, except when Circosol-2XH was present in the medium. This resulted in polymers less rich in styrene. Attempts to induce cross-linking by incorporation of vinyl crotonate or divinylbenzene into the polymers did not result in a tighter gel. In the polymerization of butadiene, there is a threshold concentration of catalyst below which no reaction occurs and above which the final conversion obtained rises rapidly to 100 per cent with increased catalyst concentration. The lower the concentration of inert diluents in the reaction system, the lower the threshold value. The intrinsic viscosity of the polymer increases as reaction temperature is raised and decreases as conversion proceeds. Intrinsic viscosities over 20 can be otained. In contrast, butadiene-styrene copolymers increase in intrinsic viscosity as conversion is increased and have a lower gel content. The intrinsic viscosity of the copolymers is much lower than for the polybutadiene samples and the catalyst requirement is higher. Polymerization will occur in the presence of butanes and butylenes, hydrocarbon oils such as Circosol-2XH, carbon black, and stearic acid although the catalyst requirements are thereby increased. Incorporation of such materials before or immediately after polymerization markedly improves the processability of the polymers. Physical evaluation of resulting masterbatches has indicated retention of desirable properties.
Structure and Properties of Loaded Rubber Mixtures. VIII. Tensile Strength of Loaded Rubber Mixtures Prepared Directly from Latex
Authors: Uzina R. , Dostian M.
Published: February 2011

1. The change of physical properties of loaded films of natural latex with the degree of loading is related to a change of distribution of the filler; when the filler content is small a loose structure is formed, which possesses a lower density and strength. 2. Mastication destroys the loose structure which forms in the range of small loadings, and leads to a disappearance of the minima on the corresponding concentration-strength and concentration-density curves. In synthetic-latex mixtures, there is no minimum strength or density for a particular degree of loading, since no loose structure is formed. This is still true after mastication. 4. In natural latex, bentonite clay is an active filler; channel carbon black hardly reinforces such latex mixtures. In synthetic latex (Igetex S-3), channel carbon black shows significant reinforcing properties. 5. Mastication of dried latex mixtures does not change the action of fillers. 6. Mastication of coagulated natural-latex mixtures causes channel carbon black to become an active filler; the behavior of fillers in synthetic latex mixtures is not changed by mastication. 7. The above mentioned phenomena are the result of the action of surface-active substances present in latex and adsorbed on the surface of its globules.
Characterization of Cord Fatigue in Tires
Authors: Williams K. R. , Hannell J. W. , Swanson J. M.
Published: February 2011

Fatigue in tire cords causes a linear loss of cord tensile strength with mileage and an increased fiber torsional stiffness. The loss in cord strength is centered mainly in the flex zone. The loss of cord strength stems from broken filaments and from a small loss of fiber strength throughout the tire. The lowered fiber strength is attributed to a lowered D.P., and does not appear to be connected with the broken filaments observed in the flex zone. The cause of the broken filaments has not been resolved. However, studies show that it is not due to abrasion or heat degradation. It was found possible to duplicate tire fatigue characteristics in the laboratory by causing cords to go through an extension-compression cycle approximately equivalent to the one in tires. Under these conditions, the Goodrich disk-type tester showed the same relative rate of strength loss for rayon and cotton cords as was found in a passenger tire fleet test.
Effect of Severity of Service on the Relative Abrasion Resistance of Natural Rubber, GR-S-10, and GR-S-100
Authors: Biard C. C. , Svetlik J. F.
Published: February 2011

The data in this report show that the rate of wear is affected very greatly by the severity of the test. Both laboratory and actual road wear performance data show that synthetic rubber and natural rubber are fairly similar in rate of wear under mild conditions of testing, but in severe service the synthetic polymers are vastly superior to natural rubber. It therefore becomes evident that, in order to correlate laboratory data with road test results, the severity of service must be known, and a laboratory test conducted under one set of conditions would not necessarily be expected to correlate with all road test results.
Thermal Decomposition of Vulcanized Structures of Deformed Vulcanizates Containing Various Accelerators
Authors: Dogadkin B. , Tarasova Z.
Published: February 2011

According to the hypotheses developed by the authors, vulcanized rubber is a system in which the molecular chains are united by local molecular and chemical bonds of varying intensity. The concentration, distribution, and strength of these bonds determine the principal physical and mechanical properties of the vulcanizates. Consequently the study of the structure of the vulcanizate is of primary practical value. The explanation of the nature of the bonds in a vulcanizate by chemical methods is very difficult, mainly because of the impossibility of distinguishing the specific chemical groups which enter into the composition of the different molecular chains from those bonds between the chains which are responsible for the development of spatial structures. From this view point, the thermo-mechanical method described below, which is based on the study of stress relaxation at different temperatures, is of great significance. As was shown by Dogadkin and Reznikovskii˘, the delayed stress relaxation in a vulcanizate at temperatures up to 70° C is caused by rupture of the local intermolecular bonds and the regrouping of the structural elements of the polymeric chains without destruction of the chemical bonds between them. Accordingly, after some time at these temperatures, a practically balanced stress is established, which depends on the number of the stronger bonds remaining. At temperatures above 70° C, rupture of the chemical bonds between the chains takes place; its speed increases with decrease of the energy activating the rupture of the given type of bond. Particularly in the case of sulfur vulcanizates, we can assume that the following types of bonds exist between the chains of the rubber: (1) —C—C—, which develop as a result of the polymerizationprocesses; (2) —C—S—C— monosulfide; (3) —C—S—S—C— disulfide, and (4) —C—Sn—C— polysulfide, formed as a result of the direct participation of the vulcanizing agent, sulfur, in the process of joining of the molecular chains. The energy of these chains can be estimated as 62.7 kcal, per mole for C—C, 54.5 kcal. per mole for C—S, and 27.5 kcal. per mole for the —S—S bond. Naturally, the heat stability of a vulcanizate will depend on which of the indicated types of bonds predominates.
Rapid Plastometry
Authors: Scott J. R.
Published: February 2011

The uses of plasticity tests, especially rapid simple tests, are discussed, with particular reference to the limitations imposed by the complex plastic behavior of unvulcanized rubbers and stocks, leading to the conclusion that simple tests are likely to be of use only for routine control of repeat, nominally identical batches. A summary is given of information collected from the industry to show under what conditions a plasticity test is required to be used in factory control. The efficiency of a plasticity test is defined, and a discussion given on how the type of instrument (rotation, extrusion or compression) and the conditions of a compression test affect both efficiency and rapidity, thus showing what conditions furnish the best form of test. It is concluded that the parallel-plate compression test is the most suitable, provided the test-piece is precompressed to a small thickness so that it can be quickly heated to the test temperature before applying the load; other factors considered are the size of compression plates and of test-piece, use of release medium (e.g., thin paper), degree of precompression, preheat period, load, compression period, and temperature. Existing rapid plastometers are described, including full details of the new Wallace modification of the Hoekstra instrument, which embodies the recommended conditions of test.