Effect of epoxidized natural rubber on thermal properties,fatigue life,and natural weathering test of styrene butadiene rubber/recycled acrylonitrile‐butadiene rubber (SBR/NBRr) blends

The utilization of waste rubber powder in polymer matrices provides an attractive strategy for polymer waste disposal. Addition of recycled acrylonitrile‐butadiene rubber (NBRr) in rubber compounds gives economic (lowering the cost of rubber compounds) as well as processing advantages. In this study, the properties of styrene butadiene rubber (SBR)/NBRr blends with and without epoxidized natural rubber (ENR‐50) as a compatibilizer were determined. The results such as thermal gravimetric analysis (TGA), fatigue life, and natural weathering test of SBR/NBRr blends with and without ENR‐50 were carried out. Results showed that TG thermograms of SBR/NBRr blends with ENR‐50 show lower thermal stability compared blends without ENR‐50. The incorporation of ENR‐50 into SBR/NBRr blends has reduced char residue compared SBR/NBRr blends without ENR‐50. The incorporation of ENR‐50 in SBR/NBRr blends has increased the rigidity of the blends thus lowering the fatigue life. The increment in tensile properties retention of SBR/NBRr blends with ENR‐50 indicated the enhancement on weathering resistant. The surfaces of SBR/NBRr blends with ENR‐50 after 6 months exposure showed a minimal severity of crack compared with SBR/NBRr blends without ENR‐50. It revealed that the scale of cracks has reduced indicating well‐retaining interfacial adhesion between SBR and NBRr with the presence of ENR‐50 as a compatibilizer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Tensile and Impact Properties of Thermoplastic Natural Rubber Reinforced Short Glass Fiber and Empty Fruit Bunch Hybrid Composites

Thermoplastic natural rubber (TPNR) hybrid composite with short glass fiber (GF) and empty fruit bunch (EFB) fiber were prepared via the melt blending method using an internal mixer type Thermo Haake 600p. The TPNR were prepared from natural rubber (NR), liquid natural rubber (LNR) and polypropylene (PP) thermoplastic, with a ratio of 20:10:70. The hybrid composites were prepared at various ratios of GF/EFB with 20% volume fraction. Premixture was performed before the material was discharged into the machine. The study also focused on the effect of fiber (glass and EFB) treatment using silane and maleic anhydride grafted polypropylene (MAgPP) as a coupling agent. In general, composite that contains 10% EFB/10% glass fiber gave an optimum tensile and impact strength for treated and untreated hybrid composites. Tensile properties increase with addition of a coupling agent because of the existence of adherence as shown in the scanning electron microscopy (SEM) micrograph. Further addition of EFB exceeding 10% reduced the Young's modulus and impact strength. However, the hardness increases with the addition of EFB fiber for the untreated composite and decreases for the treated composite.     

Underwater-laser drilling of aluminum

Pulsed-laser ablation of an aluminum bulk sample was performed both in water and air with a Q-switched Nd:YAG 1,064-nm laser over a range of high-output energies from 100 to 500 mJ. The effect of laser drilling in terms of produced crater volumes as a function of water-layer thickness was studied. The water-layer thickness was varied from 1 to 20 mm. In a special case, water droplets were added to the ablation region of the dry target in order to support ablation. Water-layer thickness in that case was estimated to be 0.5 mm. A comparison of the results obtained in air and underwater was performed. It is found that the aluminum target may be drilled more efficiently under the confinement of water compared to drilling in air environment. Further drilling efficiency can be achieved by varying the thickness of water. The optimized water thickness under the conditions of our experiment was found to be 3 mm. In that case, a 28-fold increase in crater volume and 18-fold increase in crater depth was achieved as compared to ablation in air. In underwater ablation, the formation of irregular surface structures of re-deposited material around the crater (rim) is avoided and the crater surface is smoother. In an air environment, the drilling is suppressed due to an immediate re-solidification and re-deposition of ablated material. This leads to a better characteristics of craters obtained underwater in terms of roughness, shape, volumes, and reproducibility.     

Removal of Cr(VI) and As(V) from aqueous solutions by HDTMA-modified zeolite Y

The synthesized zeolite NaY from rice husk ash (RHA) and the commercial zeolite NaY both modified with surfactants in amounts equal to 50%, 100% and 200% of their external cation exchange capacity (ECEC) were used to remove chromate and arsenate anions from aqueous solutions. While the unmodified zeolite Y had little or no affinity for the Cr(VI) and As(V) anionic species, the surfactant-modified zeolite Y (SMZY) showed significant ability to remove of these anions from the aqueous solutions. The highest chromates and arsenates adsorption efficiency was observed from solutions of pH values 3 and 8, respectively because of the dominance of the univalent species of both anions. The adsorption equilibrium data were best fitted with the Langmuir isotherm model with the highest removal capacities observed for the SMZY initially prepared considering the hexadecyltrimethyl ammonium (HDTMA) amount equal to the 100% of the ECEC of zeolite Y. Synthesized SMZY remove Cr(VI) and As(V) more than the corresponding commercial one due to its lower silica to alumina ratio. Thus, the HDTMA-covered modified zeolite Y synthesized using RHA can be used to remove Cr(VI) and As(V) from water.     

COVID-19 hospitalization rates rise exponentially with age,inversely proportional to thymic T-cell production

Here, we report that COVID-19 hospitalization rates follow an exponential relationship with age, doubling for every 16 years of age or equivalently increasing by 4.5% per year of life (R² = 0.98). This mirrors the well-studied exponential decline of both thymus volume and T-cell production, which halve every 16 years. COVID-19 can therefore be added to the list of other diseases with this property, including those caused by methicillin-resistant Staphylococcus aureus, MERS-CoV, West Nile virus, Streptococcus pneumoniae and certain cancers, such as chronic myeloid leukaemia and brain cancers. In addition, the incidence of severe disease and mortality due to COVID-19 are both higher in men, consistent with the degree to which thymic involution (and the decrease in T-cell production with age) is more severe in men compared to women. Since these properties are shared with some non-contagious diseases, we hypothesized that the age dependence does not come from social-mixing patterns, i.e. that the probability of hospitalization given infection rises exponentially, doubling every 16 years. A Bayesian analysis of daily hospitalizations, incorporating contact matrices, found that this relationship holds for every age group except for the under 20s. While older adults have fewer contacts than young adults, our analysis suggests that there is an approximate cancellation between the effects of fewer contacts for the elderly and higher infectiousness due to a higher probability of developing severe disease. Our model fitting suggests under 20s have 49–75% additional immune protection beyond that predicted by strong thymus function alone, consistent with increased juvenile cross-immunity from other viruses. We found no evidence for differences between age groups in susceptibility to infection or infectiousness to others (given disease state), i.e. the only important factor in the age dependence of hospitalization rates is the probability of hospitalization given infection. These findings suggest the existence of a T-cell exhaustion threshold, proportional to thymic output and that clonal expansion of peripheral T-cells does not affect disease risk. The strikingly simple inverse relationship between risk and thymic T-cell output adds to the evidence that thymic involution is an important factor in the decline of the immune system with age and may also be an important clue in understanding disease progression, not just for COVID-19 but other diseases as well.     

An ecophysiological model of plant–pest interactions: the role of nutrient and water availability

Empirical studies have shown that particular irrigation/fertilization regimes can reduce pest populations in agroecosystems. This appears to promise that the ecological concept of bottom-up control can be applied to pest management. However, a conceptual framework is necessary to develop a mechanistic basis for empirical evidence. Here, we couple a mechanistic plant growth model with a pest population model. We demonstrate its utility by applying it to the peach–green aphid system. Aphids are herbivores which feed on the plant phloem, deplete plants’ resources and (potentially) transmit viral diseases. The model reproduces system properties observed in field studies and shows under which conditions the diametrically opposed plant vigour and plant stress hypotheses find support. We show that the effect of fertilization/irrigation on the pest population cannot be simply reduced as positive or negative. In fact, the magnitude and direction of any effect depend on the precise level of fertilization/irrigation and on the date of observation. We show that a new synthesis of experimental data can emerge by embedding a mechanistic plant growth model, widely studied in agronomy, in a consumer–resource modelling framework, widely studied in ecology. The future challenge is to use this insight to inform practical decision making by farmers and growers.     

Investigation of the potential for a simplified exposure tool in medical nutrition (SETIM) to minimise exposures to sweeteners in young patients aged 1–3 years with PKU and CMPA

Children with phenylketonuria (PKU) and severe cow’s milk protein allergy (CMPA) consume prescribed, specially formulated, foods for special medical purposes (FSMPs) in addition to having restricted intake of normal foods. These vulnerable patients are exposed to artificial sweeteners from the consumption of a combination of both free and prescribed foods. Young patients with PKU and CMPA aged from 1 to 3 years have a higher risk of exceeding the acceptable daily intake (ADI) for sweeteners than age-matched healthy children. A probabilistic modelling approach has been adapted successfully to assess the exposure of young patients with PKU and CMPA to low-calorie sweeteners. To assist professionals in the screening and formulation of foods containing food additives for such patients, a simplified exposure method/tool has been developed. The tool is intended to ensure that total dietary exposure can be considered. The simplified tool is not intended to replace the probabilistic model but may be used as a screening tool to determine if further investigation on exposure is warranted. The aim of this study was to develop and validate this simplified exposure tool to support those currently used by healthcare professionals (HCPs) using data available from the probabilistic modelling of exposure in young children with PKU and CMPA. The probabilistic model does not allow for swift screening of exposure scenarios nor is the present EFSA Food Additive Intake Assessment Model (FAIM) fully suitable for application to medical foods. The simplified exposure tool in medical nutrition (SETIM) reported here is both reliable and consistent and provides additive usage levels which minimise regular exposure above the ADI in patients. In addition to the usefulness of SETIM for the medical nutrition industry, the tool has the potential to enhance the practice of evidence-based medical nutrition by official risk assessment bodies, registration authorities and healthcare professionals.     

Low‐temperature crystallization of La0.15Sr0.775TiO3 using ionic liquids

The n‐type thermoelectric oxide La_0.15Sr_0.775TiO₃ (LST) has been synthesized at 600°C using an ionic liquid method. The method uses the ionic liquid 1‐ethyl 3‐methylimidazolium acetate as the sole complexing agent: the lack of a second, carbon‐rich template decreases the quantity of reduced intermediate phases which form during heating. By suppressing these phases, greatly reduced temperatures can be used to crystallize the perovskite LST phase, on the nanoscale. These nanoparticles have the potential to be used to increase the figure of merit in n‐type thermoelectric oxide devices.     

Study of microalgae cultivation systems based on integrated analytic hierarchy process–life cycle optimization

Optimization of sustainable process plant configurations requires the use of systematic assessment methods based on the usage of natural resources, release of pollutants and generation of environmental impact. This paper presents an integrated life cycle optimization framework for the synthesis of microalgae cultivation systems, using a multiple objective linear program formulation; in the model, individual objective functions are aggregated and weighted using the analytic hierarchy process. Four different cultivation alternatives were used as case study to demonstrate the capability of this formulated integrated model. The model takes into account three main environmental criteria in assessing different cultivation alternatives, namely energy, water (direct and indirect water) and carbon footprints. It is determined in the case study that the open pond cultivation system is preferred compared to other alternatives.