Metal-organic vapor-phase epitaxy growth and characterization of thick (100) CdTe layers on (100) GaAs and (100) GaAs/Si substrates

The growth characteristics and crystalline quality of thick (100) CdTe-epitaxial layers grown on (100) GaAs and (100) GaAs/Si substrates in a metal-organic vapor-phase epitaxy (MOVPE) system for possible applications in x-ray imaging detectors were investigated. High-crystalline-quality epitaxial layers of thickness greater than 100 μm could be readily obtained on both types of substrates. The full width at half maximum (FWHM) values of the x-ray double-crystal rocking curve (DCRC) decreased rapidly with increasing layer thickness, and remained around 50–70 arcsec for layers thicker than 30 μm on both types of substrates. Photoluminescence (PL) measurement showed high-intensity excitonic emission with very small defect-related peaks from both types of epilayers. Stress analysis carried out by performing PL as a function of layer thickness showed the layers were strained and a small amount of residual stress, compressive in CdTe/GaAs and tensile in CdTe/GaAs/Si, remained even in the thick layers. Furthermore, the resistivity of the layers on the GaAs substrate was found to be lower than that of layers on GaAs/Si possibly because of the difference of the activation of incorporated impurity from the substrates because of the different kinds of stress existing on them. A heterojunction diode was then fabricated by growing a CdTe epilayer on an n⁺-GaAs substrate, which exhibited a good rectification property with a low value of reverse-bias leakage current even at high applied biases.     

Immobilization of hospital waste incineration ashes in glass-ceramic composites

In the paper process of sintering of hospital incineration ash as a counterpart of low-level active waste with borosilicate glass frit is presented. It is shown that low porosity glass-ceramic waste-form can be obtained at a temperature range of 850–900 °C. In the sinter, the main crystal phases are wollastonite and aegirine-augite pyroxenes which have a large isomorphous capacity of binding hazardous elements. The crystal phases are fully encapsulated by the glass that provides additional protection against environmental influence. Thus, multibarrier material can be obtained at a temperature considerably lower than vitrification. This, in turn, can improve the economics of immobilization process.     

Psychological Determinants of Using Facebook: A Research Review

In recent years, Facebook has become the most popular of social networking sites (SNSs). Due to its increasing popularity and rising number of its users, the phenomenon of Facebook has aroused academic interest as well. There has been a growing number of studies on this subject. The aim of this article is to present the main trends in Facebook research and to provide an overview of major empirical findings. Among the most intensively explored topics in Facebook research, studies that concentrate on personality and individual differences among users, the role of self-efficacy, and motivation for using that specific SNS were identified. There is also a growing trend in empirical studies that focuses on testing advanced theoretical models of Facebook usage determinants. Technology acceptance model, presented in this article, is one of the most often used among them. This kind of approach may serve as a suggestion for a methodological conceptualization in the future confirmatory research on Facebook.     

Foliate-Targeting Quantum Dots-β-Cyclodextrin Nanocarrier for Efficient Delivery of Unsymmetrical Bisacridines to Lung and Prostate Cancer Cells

Targeted drug delivery by nanocarriers molecules can increase the efficiency of cancer treatment. One of the targeting ligands is folic acid (FA), which has a high affinity for the folic acid receptors, which are overexpressed in many cancers. Herein, we describe the preparation of the nanoconjugates containing quantum dots (QDs) and β-cyclodextrin (β-CD) with foliate-targeting properties for the delivery of anticancer compound C-2028. C-2028 was bound to the nanoconjugate via an inclusion complex with β-CD. The effect of using FA in QDs-β-CD(C-2028)-FA nanoconjugates on cytotoxicity, cellular uptake, and the mechanism of internalization in cancer (H460, Du-145, and LNCaP) and normal (MRC-5 and PNT1A) cells was investigated. The QDs-β-CD(C-2028)-FA were characterized using DLS (dynamic light scattering), ZP (zeta potential), quartz crystal microbalance with dissipation (QCM-D), and UV-vis spectroscopy. The conjugation of C-2028 with non-toxic QDs or QDs-β-CD-FA did not change the cytotoxicity of this compound. Confocal microscopy studies proved that the use of FA in nanoconjugates significantly increased the amount of delivered compound, especially to cancer cells. QD_green-β-CD(C-2028)-FA enters the cells through multiple endocytosis pathways in different levels, depending on the cell line. To conclude, the use of FA is a good self-navigating molecule in the QDs platform for drug delivery to cancer cells.     

Heme Oxygenase Modulation Drives Ferroptosis in TNBC Cells

The term ferroptosis refers to a peculiar type of programmed cell death (PCD) mainly characterized by extensive iron-dependent lipid peroxidation. Recently, ferroptosis has been suggested as a potential new strategy for the treatment of several cancers, including breast cancer (BC). In particular, among the BC subtypes, triple negative breast cancer (TNBC) is considered the most aggressive, and conventional drugs fail to provide long-term efficacy. In this context, our study’s purpose was to investigate the mechanism of ferroptosis in breast cancer cell lines and reveal the significance of heme oxygenase (HO) modulation in the process, providing new biochemical approaches. HO’s effect on BC was evaluated by MTT tests, gene silencing, Western blot analysis, and measurement of reactive oxygen species (ROS), glutathione (GSH) and lipid hydroperoxide (LOOH) levels. In order to assess HO’s implication, different approaches were exploited, using two distinct HO-1 inducers (hemin and curcumin), a well-known HO inhibitor (SnMP) and a selective HO-2 inhibitor. The data obtained showed HO’s contribution to the onset of ferroptosis; in particular, HO-1 induction seemed to accelerate the process. Moreover, our results suggest a potential role of HO-2 in erastin-induced ferroptosis. In view of the above, HO modulation in ferroptosis can offer a novel approach for breast cancer treatment.     

Surface Chemical and Morphological Analysis of Chitosan/1,3-β-d-Glucan Polysaccharide Films Cross-Linked at 90 °C

The cross-linking temperature of polymers may affect the surface characteristics and molecular arrangement, which are responsible for their mechanical and physico-chemical properties. The aim of this research was to determine and explain in detail the mechanism of unit interlinkage of two-component chitosan/1,3-β-d-glucan matrices gelled at 90 °C. This required identifying functional groups interacting with each other and assessing surface topography providing material chemical composition. For this purpose, various spectroscopic and microscopic approaches, such as attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), were applied. The results indicate the involvement mainly of the C-C and C-H groups and C=O⋯HN moieties in the process of biomaterial polymerization. Strong chemical interactions and ionocovalent bonds between the N-glucosamine moieties of chitosan and 1,3-β-d-glucan units were demonstrated, which was also reflected in the uniform surface of the sample without segregation. These unique properties, hybrid character and proper cell response may imply the potential application of studied biomaterial as biocompatible scaffolds used in regenerative medicine, especially in bone restoration and/or wound healing.     

Mu and Delta Opioid Receptor Targeting Reduces Connexin 43-Based Heterocellular Coupling during Neuropathic Pain

Chronic neuropathic pain emerges from either central or peripheral lesions inducing spontaneous or amplified responses to non-noxious stimuli. Despite different pharmacological approaches to treat such a chronic disease, neuropathic pain still represents an unmet clinical need, due to long-term therapeutic regimens and severe side effects that limit application of currently available drugs. A critical phenomenon involved in central sensitization is the exchange of signalling molecules and cytokines, between glia and neurons, driving the chronicization process. Herein, using a chronic constriction injury (CCI) model of neuropathic pain, we evaluated the efficacy of the mu (M-) and delta (D-) opioid receptor (-OR) targeting agent LP2 in modulating connexin-based heterocellular coupling and cytokine levels. We found that long-term efficacy of LP2 is consequent to MOR-DOR targeting resulting in the reduction of CCI-induced astrocyte-to-microglia heterocellular coupling mediated by connexin 43. We also found that single targeting of DOR reduces TNF and IL-6 levels in the chronic phase of the disease, but the peripheral and central discharge as the primary source of excitotoxic stimulation in the spinal cord requires a simultaneous MOR-DOR targeting to reduce CCI-induced neuropathic pain.     

The Benefits of Using Saccharose for Photocatalytic Water Disinfection

In this work, the characteristics of saccharose (sucrose)-modified TiO₂ (C/TiO₂) photocatalysts obtained using a hydrothermal method at low temperature (100 °C) are presented. The influence of C/TiO₂ on survivability and enzyme activity (catalase and superoxide dismutase) of Gram-negative bacteria Escherichia coli (ATCC 29425) and Gram-positive bacteria Staphylococcus epidermidis (ATCC 49461) under UV-A and artificial solar light (ASL) were examined. The obtained TiO₂-1%-S-100 photocatalysts were capable of total E. coli and S. epidermidis inactivation under ASL irradiation in less than 1 h. In addition, the impacts of sugars on the photocatalytic activity and disinfection performance are discussed.     

Influence of laminate type on tin whisker growth in tin-rich lead-free solder alloys

This paper describes variations in whisker growth on the surface of tin-rich, lead-free alloys soldered on a Cu layer depending on the laminate used for the printed circuit board, which can be either glass-epoxy or paper-phenol. The structure of the glass-epoxy laminate surface is characterized by spatial nonuniformity caused by the regular structure formed by regions of glass fibers and resin in the top layer of the laminate. The higher value of thermal expansion of the resin than of the glass fiber means that the area of the resin expands more than that of the glass fiber. This causes local compressive stress in the solder layer and as a result promotes whisker growth in the area of the alloy soldered on the Cu layer over the glass fiber. This effect does not occur on the surface of an alloy soldered on Cu layer over a paper-phenol laminate.     

K‐12 Outreach: Identifying the Broader Impacts of Four Outreach Projects

Over the last four years, a series of outreach programs have been offered through the Colorado School of Mines to middle school teachers from eleven school districts in the State of Colorado in the United States. Each of these programs is designed to illustrate through hands‐on activities the application of mathematics to science and engineering. Each also has an academic year follow‐up such that a faculty member, an expert teacher, or a graduate student assists the teachers in the classroom. An expected outcome of this effort is the improvement of instruction in mathematics and science in the participating middle schools; an unexpected outcome has been the impact of these projects on the culture of the participating schools, both middle schools and university. Based on our assessment efforts, this article describes the qualitative and quantitative outcomes of this sequence of projects on middle school students, teachers, graduate students, professors, and college curriculum.