Correlation of electron and proton-irradiation-induced damage in InP solar cells

The measured degradation of epitaxial shallow homojunction n⁺p InP solar cells under 1-MeV electron irradiation is correlated with that measured under 3-MeV proton irradiation based on ‘displacement damage dose’. The measured data are analyzed as a function of displacement damage dose from which an electron-to-proton dose equivalency ratio is determined which enables the electron and proton degradation data to be described by a single degradation curve. It is discussed how this single curve can be used to predict the cell degradation under irradiation by any particle energy. The degradation curve is used to compare the radiation response of InP and GaAs/Ge cells on an absolute damage energy scale. The comparison shows InP to be inherently more resistant to displacement damage deposition than the GaAs/Ge.     

Poly(N-isopropylacrylamide)/mesoporous silica thermosensitive composite hydrogels for drug loading and release

Temperature-sensitive hydrogels are attracting increasing attention for controlled drug delivery. However, achieving high drug loadings and sustained drug release remains challenging. Herein, we describe the successful synthesis of a series of novel temperature-sensitive poly(N-isopropylacrylamide) (PNIPA)/mesoporous silica nanoparticles (MSN) hydrogels by physical crosslinking of NIPA with MSN. The external and internal structures, temperature sensitivity, drug-loading capacity, and blood compatibility of the PNIPA/MSN composite hydrogels are studied. Results show that MSN addition improved the network structure and adjusted the size of the hole, MSN could also act as drug carrier, thereby enhancing the drug loading capacity. The composite hydrogels underwent a phase transition at 33.7 °C (at the lower critical solution temperature). The hemolysis rate of the composite hydrogels was less than 1%, thus they can be classified as a nonhemolytic materials with good biocompatibility. The composite hydrogels reported here thus have great potential in drug transport and temperature-activated drug release. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48391.     

Biodegradable Poly(butylene adipate-co-terephthalate) composites reinforced with bio-based nanochitin: Preparation,enhanced mechanical and thermal properties

The accumulation of nonbiodegradable petrochemical-based polymers in the environment motivates the development and use of low-cost, eco-friendly, and biodegradable polymers. A series of biodegradable poly(butylene adipate-co-terephthalate) composites reinforced by sustainably sourced nanochitin were successfully prepared using melt blending and compression molding methods. Structural, thermal, and mechanical characterizations of poly(butylene adipate-co-terephthalate) (PBAT)/nanochitin composites were performed. SEM revealed that the nanochitin was uniformly dispersed throughout the PBAT matrix at low contents (<2 wt %), while DSC analyses revealed a corresponding increase in the crystallinity (32.6% enhancement) of the PBAT matrix. The tensile strength and elongation at break of the PBAT/nanochitin composite containing 0.5 wt % nanochitin were higher by 82.5 and 64.2%, respectively, compared with pristine PBAT. The Chitin-0.5 composite also showed improved thermal stability compared with PBAT (the char yield improved by 8%) due to the uniform dispersion of nanochitin in the PBAT matrix. The enhanced performance of the PBAT/nanochitin composites, prepared without an added compatibilizer, informs the development of improved biodegradable PBAT-based polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48485.     

Circulating hormones and estrous stage predict cellular and stromal remodeling in murine uterus

The understanding of how estrogen and progesterone (P(4)) drive uterine remodeling in rodents has largely been based on studies involving administration of exogenous hormones, using steroid receptor-deficient mice, or relying on vaginal smears. In all these cases, the actual serum levels of 17beta-estradiol (E(2)) and P(4) are not directly measured, and the relationship between physiological levels of female sex hormones and uterine remodeling in cycling mice has not been fully explored. Here, we measured the circulating levels of E(2) and P(4) in cycling mice and performed correlation analysis between hormone levels and epithelial and stromal uterine parameters, irrespective of the estrous stage. In parallel, these parameters were analyzed in relation to the more conventional method of vaginal smear classification of estrous stage. We found that circulating P(4) inversely correlated with uterine width, luminal epithelial proliferation, stromal apoptosis, and degradation of luminal epithelial basement membrane collagen type-IV. Circulating E(2) positively correlated with uterine width, stromal cell proliferation, and collagen type-I content, while it negatively correlated with glandular epithelial proliferation, loss of collagen type-IV surrounding glandular epithelium, and apoptosis in luminal, glandular, and stromal compartments. Our findings indicate that measuring P(4) or E(2) levels can predict many concurrent cellular and stromal events in the mouse uterus, suggesting that in naturally cycling mice cellular responses to hormone changes are not delayed, but occur very rapidly.     

Neighborhood sociodemographics and change in built infrastructure

While increasing evidence suggests an association between physical infrastructure in neighborhoods and health outcomes, relatively little research examines how neighborhoods change physically over time and how these physical improvements are spatially distributed across populations. This paper describes the change over 25 years (1985–2010) in bicycle lanes, off-road trails, bus transit service and parks, and spatial clusters of changes in these domains relative to neighborhood sociodemographics in four US cities that are diverse in terms of geography, size, and population. Across all four cities we identified increases in bicycle lanes, off-road trails, and bus transit service, with spatial clustering in these changes that related to neighborhood sociodemographics. Overall, we found evidence of positive changes in physical infrastructure commonly identified as supportive of physical activity. However, the patterning of infrastructure change by sociodemographic change encourages attention to the equity in infrastructure improvements across neighborhoods.     

Oncogenes and the Origins of Leukemias

Self-maintaining hematopoietic stem cells are a cell population that is primarily ‘at risk’ to malignant transformation, and the cell-of-origin for some leukemias. Tissue-specific stem cells replenish the different types of functional cells within a particular tissue to meet the demands of an organism. For hematopoietic stem cells, this flexibility is important to satisfy the changing requirements for a certain type of immune cell, when needed. From studies of the natural history of childhood acute lymphoblastic leukemia, an initial oncogenic and prenatal insult gives rise to a preleukemic clone. At least a second genomic insult is needed that gives rise to a leukemia stem cell: this cell generates a hierarchy of leukemia cells. For some leukemias, there is evidence to support the concept that one of the genomic insults leads to dysregulation of the tissue homeostatic role of hematopoietic stem cells so that the hierarchy of differentiating leukemia cells belongs to just one cell lineage. Restricting the expression of particular oncogenes in transgenic mice to hematopoietic stem and progenitor cells led to different human-like lineage-restricted leukemias. Lineage restriction is seen for human leukemias by virtue of their sub-grouping with regard to a phenotypic relationship to just one cell lineage.     

High-Performance Work Systems and Organizational Performance in Emerging Economies: Evidence from MNEs in Turkey

This study examines the association between the usage of high-performance work systems (HPWS) by subsidiaries of multinational enterprises (MNEs) in Turkey and employee and subsidiary level outcomes. The study is based on a survey of 148 MNE subsidiaries operating in Turkey. The results show that the usage of HPWS has a significant positive impact on employee effectiveness. However, their impact on employee skills and development, and organizational financial performance are far less clear. Our findings highlight the extent to which HWPS need to be adapted to take account of context-specific institutional realities.     

A Self-aligning Interferometer Suitable for White or Monochromatic Light Consisting Solely of a Mirror and a Reflection Grating

Abstract

A simple interferometer constructed from a mirror and a reflection grating is described. This interferometer can operate with monochromatic or wideband light, and versions of it may be constructed to suit radiations other than light, such as sound waves or matter waves. A most unusual feature of the interferometer is its high tolerance to large misalignments of its optical elements.     

The economic consequences of mortgage debt

Unsurprisingly, a great deal of attention has been paid to the economic consequences of the credit crunch. However, this paper shows that the credit crunch was preceded by a strong build-up of mortgage debt internationally, which, in the long run, could turn out to be more significant than the credit crunch itself. Indeed, the debt build-up suggests that the credit crunch is more likely to reoccur, because highly-indebted households have weaker buffers to withstand unexpected shocks to their incomes or to interest rates. The paper presents a model that can explain the debt build-up and changes to the distribution of debt between existing owners and first-time buyers, which hinders access to home-ownership for the latter, even amongst those households who would be considered as credit-worthy.