Disparities in esophageal cancer care: a population-based study.

BACKGROUND: Vulnerable populations potentially have a worse prognosis for cancer. The present study aimed to identify individual and municipal characteristics of access to health, including education, use of health insurance, gross domestic product per capita (GDPpc), and urban aspects, which could impact the prognosis of patients with esophageal cancer. METHODS: Data on urban concentration, administrative hierarchy, GDPpc, individual patient characteristics, and access to healthcare were collected from national and state public databases spanning between 2013 and 2022. The study included cities in the state of Sao Paulo, Brazil. Independent variables such as GDPpc, urban concentration, municipal administrative hierarchy, health insurance status, education level, and individual cancer and patient characteristics were evaluated against the outcomes of overall survival (OS), likelihood of undergoing surgical treatment, and time-to-treatment initiation. RESULTS: A total of 9280 patients with esophageal cancer (85% squamous cell carcinoma and 15% adenocarcinoma) treated in 42 cities were included in the study. In univariate analysis, higher education (hazard ratio [HR] = 0.6; P < .001), female gender (HR = 0.85; P < .001), and having private health insurance (HR = 0.65; P < .001) were identified as protective factors for OS in esophageal cancer. After adjusting for other variables in multivariate analysis, higher education (HR = 0.77; P = .009), female gender (HR = 0.82; P < .001), and private insurance (HR = 0.65; P < .001) remained protective factors. GDPpc was not associated with OS. Urban concentration and hierarchy influenced the likelihood of receiving surgical treatment. Patients from high urban concentrations had shorter time-to-treatment initiation intervals. CONCLUSION: Populations at risk, particularly those with limited access to education and healthcare, face a worse prognosis for esophageal cancer.

Discriminative value of pulse wave velocity for arterial stiffness and cardiac injury in prediabetic patients.

Background: Prediabetes (PD) is defined as impaired fasting glucose and/or impaired glucose tolerance (IGT) and may be associated with high risk of cardiovascular injury. It is recommended that PD patients be screened for signs of arterial stiffness and cardiovascular injury to reinforce therapeutic strategies. Objectives: To identify pulse wave velocity values discriminative for arterial stiffness and cardiovascular injury in PD patients. Methods: A cross-sectional study was conducted with PD (N=43) and normoglycemic (N=37) patients who underwent clinical evaluation, arterial stiffness assessment by carotid-femoral pulse wave velocity (cfPWV) using SphygmoCor, laboratory blood analysis, investigation of morphological and functional cardiac variables by transthoracic echocardiogram, and assessment of carotid intima-media-thickness (CIMT) by carotid ultrasonography. A statistical analysis was performed using SPSS software and values of p<0.05 were considered significant. Results: A cfPWV cut-off value of 6.9 m/s was identified for IGT (Sensitivity [SE]: 74% and Specificity [SP]: 51%). Comparison of general data and risk factors between subsets with values above and below this cutoff value revealed higher rates of fasting glucose (p=0.02), obesity (p=0.03), dyslipidemia (p=0.004), early signs of left ventricle (p=0.017) and right ventricle (p=0.03) impaired diastolic function, and elevated CIMT in subjects with cfPWV ≥ 6.9m/s (p=0.04). Conclusions: In PD patients, a cfPWV cutoff of 6.9 m/s was considered a discriminative value for arterial stiffness. These findings highlight the value of early investigation of cardiovascular injury and aggressive therapy strategies with good control of risk factors in PD.

Contexto: O pré-diabetes (PD) é definido como glicemia de jejum alterada e/ou tolerância à glicose alterada (TGA) e pode estar associado a alto risco de lesão cardiovascular. Recomenda-se discriminar quais pacientes com PD podem apresentar sinais de rigidez arterial e lesão cardiovascular para reforçar as estratégias terapêuticas. Objetivos: Identificar os valores discriminativos da velocidade de onda de pulso determinantes de rigidez arterial e lesão cardiovascular em pacientes com PD. Métodos: Estudo transversal em pacientes com PD (N=43) e normoglicêmicos (N=37) submetidos a avaliação clínica, avaliação da rigidez arterial pela velocidade da onda de pulso carótido-femoral (cfPWV) utilizando SphygmoCor, análise laboratorial de sangue, investigação de alterações morfológicas e variáveis cardíacas funcionais por ecocardiograma transtorácico e avaliação da espessura íntima-média carotídea (EIMC) pela ultrassonografia da carótida. A análise estatística foi realizada no software SPSS, e valores de p<0,05 foram considerados significativos. Resultados: Foi identificado um valor de corte cfPWV de 6,9 m/s para TGA (sensibilidade 74% e especificidade 51%). A comparação dos dados e fatores de risco entre valores acima e abaixo do valor de corte estabelecido revelou glicemia de jejum elevada (p=0,02), obesidade (p=0,03), dislipidemia (p=0,004), sinais precoces de função diastólica prejudicada do ventrículo esquerdo (p=0,017) e ventrículo direito (p=0,03) e maior EIMC em cfPWV ≥6,9m/s (p=0,04). Conclusões: Em pacientes com PD, o cfPWV de 6,9 m/s foi considerado um valor discriminativo de rigidez arterial. Esses achados reforçam que a investigação precoce da lesão cardiovascular e uma estratégia com terapia agressiva são valiosas no controle dos fatores de risco na PD.

Discriminative value of pulse wave velocity for arterial stiffness and cardiac injury in prediabetic patients / Valor discriminativo da velocidade da onda de pulso para rigidez arterial e lesão cardíaca em pacientes pré-diabéticos

Abstract Background Prediabetes (PD) is defined as impaired fasting glucose and/or impaired glucose tolerance (IGT) and may be associated with high risk of cardiovascular injury. It is recommended that PD patients be screened for signs of arterial stiffness and cardiovascular injury to reinforce therapeutic strategies. Objectives To identify pulse wave velocity values discriminative for arterial stiffness and cardiovascular injury in PD patients. Methods A cross-sectional study was conducted with PD (N=43) and normoglycemic (N=37) patients who underwent clinical evaluation, arterial stiffness assessment by carotid-femoral pulse wave velocity (cfPWV) using SphygmoCor, laboratory blood analysis, investigation of morphological and functional cardiac variables by transthoracic echocardiogram, and assessment of carotid intima-media-thickness (CIMT) by carotid ultrasonography. A statistical analysis was performed using SPSS software and values of p<0.05 were considered significant. Results A cfPWV cut-off value of 6.9 m/s was identified for IGT (Sensitivity [SE]: 74% and Specificity [SP]: 51%). Comparison of general data and risk factors between subsets with values above and below this cutoff value revealed higher rates of fasting glucose (p=0.02), obesity (p=0.03), dyslipidemia (p=0.004), early signs of left ventricle (p=0.017) and right ventricle (p=0.03) impaired diastolic function, and elevated CIMT in subjects with cfPWV ≥ 6.9m/s (p=0.04). Conclusions In PD patients, a cfPWV cutoff of 6.9 m/s was considered a discriminative value for arterial stiffness. These findings highlight the value of early investigation of cardiovascular injury and aggressive therapy strategies with good control of risk factors in PD.

Resumo Contexto O pré-diabetes (PD) é definido como glicemia de jejum alterada e/ou tolerância à glicose alterada (TGA) e pode estar associado a alto risco de lesão cardiovascular. Recomenda-se discriminar quais pacientes com PD podem apresentar sinais de rigidez arterial e lesão cardiovascular para reforçar as estratégias terapêuticas. Objetivos Identificar os valores discriminativos da velocidade de onda de pulso determinantes de rigidez arterial e lesão cardiovascular em pacientes com PD. Métodos Estudo transversal em pacientes com PD (N=43) e normoglicêmicos (N=37) submetidos a avaliação clínica, avaliação da rigidez arterial pela velocidade da onda de pulso carótido-femoral (cfPWV) utilizando SphygmoCor, análise laboratorial de sangue, investigação de alterações morfológicas e variáveis cardíacas funcionais por ecocardiograma transtorácico e avaliação da espessura íntima-média carotídea (EIMC) pela ultrassonografia da carótida. A análise estatística foi realizada no software SPSS, e valores de p<0,05 foram considerados significativos. Resultados Foi identificado um valor de corte cfPWV de 6,9 m/s para TGA (sensibilidade 74% e especificidade 51%). A comparação dos dados e fatores de risco entre valores acima e abaixo do valor de corte estabelecido revelou glicemia de jejum elevada (p=0,02), obesidade (p=0,03), dislipidemia (p=0,004), sinais precoces de função diastólica prejudicada do ventrículo esquerdo (p=0,017) e ventrículo direito (p=0,03) e maior EIMC em cfPWV ≥6,9m/s (p=0,04). Conclusões Em pacientes com PD, o cfPWV de 6,9 m/s foi considerado um valor discriminativo de rigidez arterial. Esses achados reforçam que a investigação precoce da lesão cardiovascular e uma estratégia com terapia agressiva são valiosas no controle dos fatores de risco na PD.

Ferric Ions Crosslinked Epoxidized Natural Rubber Filled with Carbon Nanotubes and Conductive Carbon Black Hybrid Fillers.

Natural rubber with 50 mol % epoxidation (ENR-50) was filled with carbon nanotubes (CNTs) and conductive carbon black (CCB) hybrid fillers with various CCB loadings of 2.5, 5.0, 7.0, 10.0 and 15.0 phr, and the compounds were mixed with ferric ion (Fe3+) as a crosslinking agent. The ENRs filled exclusively with CNTs, and CNT-CCB hybrid fillers exhibited typical curing curves at different CCB loadings, i.e., increasing torque with time and thus crosslinked networks. Furthermore, the incorporation of CNT-CCB hybrid fillers and increasing CCB loadings caused an enhancement of tensile properties (modulus and tensile strength) and crosslink densities, which are indicated by the increasing torque difference and the crosslink densities. The crosslink densities are determined by swelling and temperature scanning stress relaxation (TSSR). Increasing CCB loadings also caused a significant improvement in bound rubber content, filler-rubber interactions, thermal resistance, glass transition temperature (Tg) and electrical conductivity. A combination of 7 phr CNT and CCB with loading higher than 2.5 phr gave superior properties to ENR vulcanizates. Furthermore, the secondary CCB filler contributes to the improvement of CNT dispersion in the ENR matrix by networking the CNT capsules and forming CNT-CCB-CNT pathways and thus strong CNT-CCB networks, indicating the improvement in the tensile properties, bound rubber content and dynamic properties of the ENR composites. Moreover, higher electrical conductivity with a comparatively low percolation threshold of the hybrid composites was found as compared to the ENR filled with CNTs without CCB composite. The superior mechanical and other properties are due to the finer dispersion and even distribution of CNT-CCB hybrid fillers in the ENR matrix.

Infiltration of the Hoffa's fat pad with stromal vascular fraction in patients with osteoarthritis of the knee -Results after one year of follow-up.

Objectives: Cell therapy using multipotential stromal cells (MSCs) is being used in a variety of clinical settings to induce tissue regeneration. Promising results have also been achieved in the therapy of osteoarthritis. MSCs have been demonstrated to be safe (Borakati et al., 2018). They can be used in a one step procedure as minimally manipulated mesenchymal stem cells or after in vitro expansion. The in vitro step allows for the selection of a more homogeneous cell population, meeting the standard criteria for MSC identification (Lv et al., 2014). In vitro expansion of MSCs is cost intensive, time consuming and furthermore associated with gradual accumulation of senescent cells (Wagner et al., 2008), telomere erosion (Baxter et al., 2004), and changing phenotypes (Jones et al., 2010; Halfon et al., 2011). These disadvantages could be surpassed by the use of "minimally manipulated mesenchymal stem cells" from bone marrow or adipose tissue (Di Matteo et al., 2019) such as the adipogenic stromal-vascular fraction (SVF).The study investigates whether infiltration of the Hoffa fat pad with autologous SVF is an effective and safe treatment option for patients with gonarthrosis. Furthermore, the number and vitality of the injected cells as well as the clinical efficacy will be evaluated. Materials and methods: We conduct a prospective study. Patients with osteoarthritis of the knee receive infiltration of SVF into the Hoffa fat pad. The number and vitality of the cells are measured with a cell counter. The clinical outcome is checked using VAS, KOOS and SF12 questionnaires with a follow-up period of 1 year. Results: A total of 33 patients and 36 knees were included in this Study. An average of 45 million cells were injected with a standard deviation of 2,5 million Cells. After 6 months a significant improvement of the VAS and the respective subscales of the KOOS could be observed compared to the baseline. After one year of follow-up, a significant improvement in all KOOS subscales compared to baseline was still observed. A significant correlation between reduced knee pain on the VAS and the number of injected cells could be observed as well. Thus, patients injected with a higher number of cells seem to have a better outcome. The average viability of the cells was 64,4% with a standard deviation of 15,9%. A correlation between higher cell viability and better outcome on the QOL subscale of the KOOS was observed. There were no major complications or side effects. Discussion: These initial results indicate that treatment with SVF is a safe therapeutic option that has the potential to relieve joint pain and significantly improved function. The cell number and vitality of the injected cells appear to be important factors influencing the success of the therapy.

Development of Liquid Diene Rubber Based Highly Deformable Interactive Fiber-Elastomer Composites.

The preparation of intelligent structures for multiple smart applications such as soft-robotics, artificial limbs, etc., is a rapidly evolving research topic. In the present work, the preparation of a functional fabric, and its integration into a soft elastomeric matrix to develop an adaptive fiber-elastomer composite structure, is presented. Functional fabric, with the implementation of the shape memory effect, was combined with liquid polybutadiene rubber by means of a low-temperature vulcanization process. A detailed investigation on the crosslinking behavior of liquid polybutadiene rubber was performed to develop a rubber formulation that is capable of crosslinking liquid rubber at 75 °C, a temperature that is much lower than the phase transformation temperature of SMA wires (90-110 °C). By utilizing the unique low-temperature crosslinking protocol for liquid polybutadiene rubber, soft intelligent structures containing functional fabric were developed. The adaptive structures were successfully activated by Joule heating. The deformation behavior of the smart structures was experimentally demonstrated by reaching a 120 mm bending distance at an activation voltage of 8 V without an additional load, whereas 90 mm, 70 mm, 65 mm, 57 mm bending distances were achieved with attached weights of 5 g, 10 g, 20 g, 30 g, respectively.

A Comprehensive Study about the Role of Crosslink Density on the Tribological Behavior of DLC Coated Rubber.

The friction and wear behavior of coated rubber components is strongly dependent on the substrate properties. This work deals with the impact of the crosslink density, i.e., the hardness of the rubber substrate on the tribological performance of uncoated and coated rubber. The hardness of nitrile butadiene rubber (NBR) is varied altering the sulfur content. Both the uncoated and coated rubber samples are characterized in terms of surface and mechanical properties. Tribological tests comprise the examination of the macroscopic contact area and the temperature in the contact zone. It was found that the functional layer enhances the wear resistance significantly. Apparently, the wear and friction behavior of the coated rubber correlates with the hardness and the bulk properties of the substrate material.

Effect of Prestrain on the Actuation Characteristics of Dielectric Elastomers.

Dielectric elastomers (DEs) represent a class of electroactive polymers that deform due to electrostatic attraction between oppositely charged electrodes under a varying electric field. Over the last couple of decades, DEs have garnered considerable attention due to their much-coveted actuation properties. As far as the precise measurement systems are concerned, however, there is no standard instrument or interface to quantify various related parameters, e.g., actuation stress, strain, voltage and creeping etc. In this communication, we present an in-depth study of dielectric actuation behavior of dielectric rubbers by the state-of-the-art "Dresden Smart Rubber Analyzer" (DSRA), designed and developed in-house. The instrument allowed us to elucidate various factors that could influence the output efficiency of the DEs. Herein, several non-conventional DEs such as hydrogenated nitrile rubber, nitrile rubber with different acrylonitrile contents, were employed as an electro-active matrix. The effect of viscoelastic creeping on the prestrain, molecular architecture of the matrices, e.g., nitrile content of nitrile-butadiene rubber (NBR) etc., are also discussed in detail.

Poly(acrylonitrile-co-butadiene) as polymeric crosslinking accelerator for sulphur network formation.

The major controlling factors that determine the various mechanical properties of an elastomer system are type of chemical crosslinking and crosslink density of the polymer network. In this study, a catalytic amount of acrylonitrile butadiene copolymer (NBR) was used as a co-accelerator for the curing of polybutadiene (BR) elastomer. After the addition of this copolymer along with other conventional sulphur ingredients in polybutadiene compounds, a clear and distinct effect on the curing and other physical characteristics was noticed. The crosslinking density of BR was increased, as evidenced by rheometric properties, solid-state NMR and swelling studies. The vulcanization kinetics study revealed a substantial lowering of the activation energy of the sulphur crosslinking process when acrylonitrile butadiene copolymer was used in the formulation. The compounds were also prepared in the presence of carbon black and silica, and it was found that in the carbon black filled system the catalytic effect of the NBR was eminent. The effect was not only reflected in the mechanical performance but also the low-temperature crystallization behavior of BR systems was altered.

Friction, Abrasion and Crack Growth Behavior of In-Situ and Ex-Situ Silica Filled Rubber Composites.

The article focuses on comparing the friction, abrasion, and crack growth behavior of two different kinds of silica-filled tire tread compounds loaded with (a) in-situ generated alkoxide silica and (b) commercial precipitated silica-filled compounds. The rubber matrix consists of solution styrene butadiene rubber polymers (SSBR). The in-situ generated particles are entirely different in filler morphology, i.e., in terms of size and physical structure, when compared to the precipitated silica. However, both types of the silicas were identified as amorphous in nature. Influence of filler morphology and surface modification of silica on the end performances of the rubbers like dynamic friction, abrasion index, and fatigue crack propagation were investigated. Compared to precipitated silica composites, in-situ derived silica composites offer better abrasion behavior and improved crack propagation with and without admixture of silane coupling agents. Silane modification, particle morphology, and crosslink density were identified as further vital parameters influencing the investigated rubber properties.

Water-Responsive and Mechanically Adaptive Natural Rubber Composites by in Situ Modification of Mineral Filler Structures.

A new biomimetic stimuli-responsive adaptive elastomeric material, whose mechanical properties are altered by a water treatment is reported in this paper. This material is a calcium sulphate (CaSO4) filled composite with an epoxidized natural rubber (ENR) matrix. By exploiting various phase transformation processes that arise when CaSO4 is hydrated, several different crystal structures of CaSO4· xH2O can be developed in the cross-linked ENR matrix. Significant improvements in the mechanical and thermal properties are then observed in the water-treated composites. When compared with the untreated sample, there is approximately 100% increase in the dynamic modulus. The thermal stability of the composites is also improved by increasing the maximum degradation rate temperature by about 20 °C. This change in behavior results from an in situ development of hydrated crystal structures of the nanosized CaSO4 particles in the ENR matrix, which has been verified using Raman spectroscopy, transmission electron microscopy, atomic force microscopy, and X-ray scattering. This work provides a promising and relatively simple pathway for the development of next generation of mechanically adaptive elastomeric materials by an eco-friendly route, which may eventually also be developed into an innovative biodegradable and biocompatible smart polymeric material.

Blending In Situ Polyurethane-Urea with Different Kinds of Rubber: Performance and Compatibility Aspects.

Specific physical and reactive compatibilization strategies are applied to enhance the interfacial adhesion and mechanical properties of heterogeneous polymer blends. Another pertinent challenge is the need of energy-intensive blending methods to blend high-tech polymers such as the blending of a pre-made hard polyurethane (-urea) with rubbers. We developed and investigated a reactive blending method to prepare the outstanding blends based on polyurethane-urea and rubbers at a low blending temperature and without any interfacial compatibilizing agent. In this study, the polyurethane-urea (PUU) was synthesized via the methylene diphenyl diisocyanate end-capped prepolymer and m-phenylene diamine based precursor route during blending at 100 °C with polar (carboxylated nitrile rubber (XNBR) and chloroprene rubber (CR)) and non-polar (natural rubber (NR), styrene butadiene rubber (sSBR), and ethylene propylene butadiene rubber (EPDM)) rubbers. We found that the in situ PUU reinforces the tensile response at low strain region and the dynamic-mechanical response up to 150 °C in the case of all used rubbers. Scanning electron microscopy reveals a stronger rubber/PUU interface, which promotes an effective stress transfer between the blend phases. Furthermore, energy filtered transmission electron microscopy (EFTEM) based elemental carbon map identifies an interphase region along the interface between the nitrile rubber and in situ PUU phases of this exemplary blend type.

In Situ Polymorphic Alteration of Filler Structures for Biomimetic Mechanically Adaptive Elastomer Nanocomposites.

A mechanically adaptable elastomer composite is prepared with reversible soft-stiff properties that can be easily controlled. By the exploitation of different morphological structures of calcium sulfate, which acts as the active filler in a soft elastomer matrix, the magnitude of filler reinforcement can be reversibly altered, which will be reflected in changes of the final stiffness of the material. The higher stiffness, in other words, the higher modulus of the composites, is realized by the in situ development of fine nanostructured calcium sulfate dihydrate crystals, which are formed during exposure to water and, further, these highly reinforcing crystals can be transformed to a nonreinforcing hemihydrate mesocrystalline structure by simply heating the system in a controlled way. The Young's modulus of the developed material can be reversibly altered from ∼6 to ∼17 MPa, and the dynamic stiffness (storage modulus at room temperature and 10 Hz frequency) alters its value in the order of 1000%. As the transformation is related to the presence of water molecules in the crystallites, a hydrophilic elastomer matrix was selected, which is a blend of two hydrophilic polymers, namely, epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer and a terpolymer of ethylene oxide-propylene oxide-allyl glycidyl ether. For the first time, this method also provides a route to regulate the morphology and structure of calcium sulfate nanocrystals in a confined ambient of cross-linked polymer chains.

Entrapped Styrene Butadiene Polymer Chains by Sol-Gel-Derived Silica Nanoparticles with Hierarchical Raspberry Structures.

A sol-gel transformation of liquid silica precursor to solid silica particles was carried out in a one-pot synthesis way, where a solution of styrene butadiene elastomer was present. The composites, thus produced, offered remarkable improvements of mechanical and dynamic mechanical performances compared to precipitated silica. The morphological analysis reveals that the alkoxy-based silica particles resemble a raspberry structure when the synthesis of the silica was carried out in the presence of polymer molecules and represent a much more open silica-network structure. However, in the absence of the polymer, the morphology of the silica particles is found to be different. It is envisaged that the special morphology of the in situ synthesized silica particles contributes to the superior reinforcement effects, which are associated with a strong silica-rubber interaction by rubber chains trapped inside the raspberry-like silica aggregates. Therefore, the interfaces are characterized in detail by low-field solid-state 1H NMR spectroscopy, 29Si solid-state NMR spectroscopy, and energy-dispersive X-ray spectroscopy. Low-field 1H NMR-based double-quantum experiments provide a quantitative information about the cross-link density of the silica-filled rubber composites and about the influence of silane coupling agent on the chemical cross-link density of the network and correlates well with equilibrium swelling measurements. The special microstructure of the alkoxy-based silica was found to be associated with the interaction between alkoxy-based silica and rubber chains as a consequence of particle growth in the presence of rubber chains.

Temperature Scanning Stress Relaxation of an Autonomous Self-Healing Elastomer Containing Non-Covalent Reversible Network Junctions.

In this work, we report about the mechanical relaxation characteristics of an intrinsically self-healable imidazole modified commercial rubber. This kind of self-healing rubber was prepared by melt mixing of 1-butyl imidazole with bromo-butyl rubber (bromine modified isoprene-isobutylene copolymer, BIIR). By this melt mixing process, the reactive allylic bromine of bromo-butyl rubber was converted into imidazole bromide salt. The resulting development of an ionic character to the polymer backbone leads to an ionic association of the groups which ultimately results to the formation of a network structure of the rubber chains. The modified BIIR thus behaves like a robust crosslinked rubber and shows unusual self-healing properties. The non-covalent reversible network has been studied in detail with respect to stress relaxation experiments, scanning electron microscopic and X-ray scattering.

Few-mode fiber, splice and SDM component characterization by spatially-diverse optical vector network analysis.

This paper discusses spatially diverse optical vector network analysis for space division multiplexing (SDM) component and system characterization, which is becoming essential as SDM is widely considered to increase the capacity of optical communication systems. Characterization of a 108-channel photonic lantern spatial multiplexer, coupled to a 36-core 3-mode fiber, is experimentally demonstrated, extracting the full impulse response and complex transfer function matrices as well as insertion loss (IL) and mode-dependent loss (MDL) data. Moreover, the mode-mixing behavior of fiber splices in the few-mode multi-core fiber and their impact on system IL and MDL are analyzed, finding splices to cause significant mode-mixing and to be non-negligible in system capacity analysis.

Strong Strain Sensing Performance of Natural Rubber Nanocomposites.

A detail study concerning the strain (tensile) dependent electrical conductivity of elastomeric composites is reported in this present paper. Multiwall carbon nanotubes (CNT), conducting carbon black (CB), and their combinations were considered as conducting filler in cross-linked natural rubber matrix. The loadings of the fillers were considered from 3 to 11 phr (filler concentration close to their percolation threshold). Without hindering the elastic nature of the composite (reversible stretchability up to several 100%), the change of relative resistance, ΔR/R0 (ΔR is the change in the resistance with respect to strain and R0 is the initial resistance of the sample) of the CB filled composites was found to be as much as ∼1300 at around 120% elongation. This value is much higher than any other reported values obtained from conducting polymeric composites. It was found that CNT offered a strong strain dependent character in the regime 100% to 150% elongation, whereas, the carbon black filled natural rubber showed strong strain dependencies at 50% to 100% elongation strain. The combination of two different fillers could be exploited to tailor and manipulate the sensing operating regime from 50% to 150% strain depending on the ratios of the two filler system. Additionally, after several loading-unloading cycles, the conductivity of the sample was very stable for CB filled system but for CNT filled system the conductivity of the sample was altered. This type of elastic materials could be used in structural health monitoring, sensors in different dynamic elastomeric parts like tires, valves, gaskets, engine mounts, etc.

Temperature-Dependent Reinforcement of Hydrophilic Rubber Using Ice Crystals.

This is the first study on the impact of ice crystals on glass transition and mechanical behavior of soft cross-linked elastomers. A hydrophilic elastomer such as epichlorohydrin-ethylene oxide-allyl glycidyl ether can absorb about ∼40 wt % of water. The water-swollen cross-linked network exhibits elastic properties with more than 1500% stretchability at room temperature. Coincidently, the phase transition of water into solid ice crystals inside of the composites allows the reinforcement of the soft elastomer mechanically at lower temperatures. Young's modulus of the composites measured at -20 °C remarkably increased from 1.45 to 3.14 MPa, whereas at +20 °C, the effect was opposite and the Young's modulus decreased from 0.6 to 0.03 MPa after 20 days of water treatment. It was found that a part of the absorbed water, ∼74% of the total absorbed water, is freezable and occupies nearly 26 vol % of the composites. Simultaneously, these solid ice crystals are found to be acting as a reinforcing filler at lower temperatures. The size of these ice crystals is distributed in a relatively narrow range of 400-600 nm. The storage modulus (E') of the ice crystal-filled composites increased from 3 to 13 MPa at -20 °C. The glass transition temperature (-37 °C) of the soft cross-linked elastomer was not altered by the absorption of water. However, a special transition (melting of ice) occurred at temperatures close to 0 °C as observed in the dynamic mechanical analysis of the water-swollen elastomers. The direct polymer/filler (ice crystals) interaction was demonstrated by strain sweep experiments and investigated using Fourier transform infrared spectroscopy. This type of cross-linked rubber could be integrated into a smart rubber application such as in adaptable mechanics, where the stiffness of the rubber can be altered as a function of temperature without affecting the mechanical stretchability either below or above 0 °C (above the glass temperature region) of the rubber.

Complete lymph node dissection versus no dissection in patients with sentinel lymph node biopsy positive melanoma (DeCOG-SLT): a multicentre, randomised, phase 3 trial.

BACKGROUND: Complete lymph node dissection is recommended in patients with positive sentinel lymph node biopsy results. To date, the effect of complete lymph node dissection on prognosis is controversial. In the DeCOG-SLT trial, we assessed whether complete lymph node dissection resulted in increased survival compared with observation. METHODS: In this multicentre, randomised, phase 3 trial, we enrolled patients with cutaneous melanoma of the torso, arms, or legs from 41 German skin cancer centres. Patients with positive sentinel lymph node biopsy results were eligible. Patients were randomly assigned (1:1) to undergo complete lymph node dissection or observation with permuted blocks of variable size and stratified by primary tumour thickness, ulceration of primary tumour, and intended adjuvant interferon therapy. Treatment assignment was not masked. The primary endpoint was distant metastasis-free survival and analysed by intention to treat. All patients in the intention-to-treat population of the complete lymph node dissection group were included in the safety analysis. This trial is registered with ClinicalTrials.gov, number NCT02434107. Follow-up is ongoing, but the trial no longer recruiting patients. FINDINGS: Between Jan 1, 2006, and Dec 1, 2014, 5547 patients were screened with sentinel lymph node biopsy and 1269 (23%) patients were positive for micrometastasis. Of these, 483 (39%) agreed to randomisation into the clinical trial; due to difficulties enrolling and a low event rate the trial closed early on Dec 1, 2014. 241 patients were randomly assigned to the observation group and 242 to the complete lymph node dissection group. Ten patients did not meet the inclusion criteria, so 233 patients were analysed in the observation group and 240 patients were analysed in the complete lymph node dissection group, as the intention-to-treat population. 311 (66%) patients (158 in the observation group and 153 in the dissection group) had sentinel lymph node metastases of 1 mm or less. Median follow-up was 35 months (IQR 20-54). Distant metastasis-free survival at 3 years was 77·0% (90% CI 71·9-82·1; 55 events) in the observation group and 74·9% (69·5-80·3; 54 events) in the complete lymph node dissection group. In the complete lymph node dissection group, grade 3 and 4 events occurred in 15 patients (6%) and 19 patients (8%) patients, respectively. Adverse events included lymph oedema (grade 3 in seven patients, grade 4 in 13 patients), lymph fistula (grade 3 in one patient, grade 4 in two patients), seroma (grade 3 in three patients, no grade 4), infection (grade 3 in three patients, no grade 4), and delayed wound healing (grade 3 in one patient, grade 4 in four patients); no serious adverse events were reported. INTERPRETATION: Although we did not achieve the required number of events, leading to the trial being underpowered, our results showed no difference in survival in patients treated with complete lymph node dissection compared with observation only. Consequently, complete lymph node dissection should not be recommended in patients with melanoma with lymph node micrometastases of at least a diameter of 1 mm or smaller. FUNDING: German Cancer Aid.

Ionic Modification Turns Commercial Rubber into a Self-Healing Material.

Invented by Charles Goodyear, chemical cross-linking of rubbers by sulfur vulcanization is the only method by which modern automobile tires are manufactured. The formation of these cross-linked network structures leads to highly elastic properties, which substantially reduces the viscous properties of these materials. Here, we describe a simple approach to converting commercially available and widely used bromobutyl rubber (BIIR) into a highly elastic material with extraordinary self-healing properties without using conventional cross-linking or vulcanising agents. Transformation of the bromine functionalities of BIIR into ionic imidazolium bromide groups results in the formation of reversible ionic associates that exhibit physical cross-linking ability. The reversibility of the ionic association facilitates the healing processes by temperature- or stress-induced rearrangements, thereby enabling a fully cut sample to retain its original properties after application of the self-healing process. Other mechanical properties, such as the elastic modulus, tensile strength, ductility, and hysteresis loss, were found to be superior to those of conventionally sulfur-cured BIIR. This simple and easy approach to preparing a commercial rubber with self-healing properties offers unique development opportunities in the field of highly engineered materials, such as tires, for which safety, performance, and longer fatigue life are crucial factors.