Silver nanoparticle incorporated poly(l‐lactide‐co‐glycolide) nanofibers: Evaluation of their biocompatibility and antibacterial properties

The objective of this work is the fabrication of poly(l ‐lactide‐co‐glycolide) or PLGA (with LA/GA ratios of 50/50 and 75/25) nanofibers containing silver nanoparticles (AgNPs) by the method of electrospinning. The incorporation of AgNPs in PLGA was carried out in three different concentrations (1, 3, 6 w/w %).The electrospun nanofibers were evaluated for their morphology by scanning electron microscopy and their fiber diameters ranged between 487 and 781 nm. Integration of AgNPs within the fibers was verified by spectroscopy studies, while the mechanical properties of the developed fibers were found comparable to the mechanical properties of the human skin. Proliferation of human dermal fibroblasts (HDF) demonstrated minimal cytotoxicity on fibers containing 1 wt % and 3 wt % of AgNPs, while 6 wt % of AgNPs inhibited cell proliferation. Antimicrobial activity was studied using three different strains of Gram‐positive and Gram‐negative bacteria. Results of the HDF proliferation and antimicrobial studies showed that the electrospun PLGA75/25 containing 3 wt % AgNP can function as a suitable substrate for wound dressing, compared to the other scaffolds of this study. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42686.     

3‐Deazaneplanocin A and Neplanocin A Analogues and Their Effects on Apoptotic Cell Death

3‐Deazaneplanocin A (DzNep) is a potential epigenetic drug for the treatment of various cancers. DzNep has been reported to deplete histone methylations, including oncogenic EZH2 complex, giving rise to epigenetic modifications that reactivate many silenced tumor suppressors in cancer cells. Despite its promise as an anticancer drug, little is known about the structure–activity relationships of DzNep in the context of epigenetic modifications and apoptosis induction. In this study, a number of analogues of DzNep were examined for DzNep‐like ability to induce synergistic apoptosis in cancer cells in combination with trichostatin A, a known histone deacetylase (HDAC) inhibitor. The structure–activity relationship data thus obtained provide valuable information on the structural requirements for biological activity. The studies identified three compounds that show similar activities to DzNep. Two of these compounds show good pharmacokinetics and safety profiles. Attempts to correlate the observed synergistic apoptotic activities with measured S‐adenosylhomocysteine hydrolase (SAHH) inhibitory activities suggest that the apoptotic activity of DzNep might not be directly due to its inhibition of SAHH.     

Examination of Exopolysaccharide Produced by Lactobacillus delbrueckii subsp. bulgaricus Using Confocal Laser Scanning and Scanning Electron Microscopy Techniques

ABSTRACT: Exopolysaccharide (EPS) produced by Lactobacillus delbrueckii subsp. bulgaricus NCFB 2483 (2483) was examined using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) techniques. These microscopy techniques were used to probe the location and distribution of EPS in milk permeate-based media. In CLSM, lectin (SBA) (from Glycine max ) Alexa Fluor 488 conjugate was used to stain the EPS. The EPS appeared randomly distributed as aggregates in the culture media. The CLSM technique was simple to perform with minimal sample preparation, was nonintrusive, and allowed in-situ examination of EPS. At high magnifications using SEM, the EPS aggregates appeared as web-like structures distributed through the interstices of the protein matrix. The web-like structures were apparent, especially in the sample treated with Flavourzyme, which hydrolyzed the milk proteins. The formation of the intricate web-like structures could be attributed to the dehydration of the EPS during the critical point drying process of the SEM specimens. The present investigation also found that the 2483 EPS network remained intact at neutral or low pH (approximately 3.9). However, the 2483 EPS was highly susceptible under alkaline pH conditions. Increasing the pH from 8 to 10 appeared to destroy EPS structure as indicated by a loss of its "ropy" characteristics as well as the EPS levels.     

Planning the Green New Deal: Climate Justice and the Politics of Sites and Scales

Abstract

Climate change and the rise of a grassroots–legislative political–environmental movement in the United States should change how urban planners think and act on spatial change and social justice. After the 2018?U.S. elections, organizing movements and progressive legislators endorsed the Green New Deal. In this Viewpoint I look at the Green New Deal’s potential implications for urban planning. I analyze it in reference to the 1930s’ New Deal inspirations and current climate and urban challenges, and illustrate the contradictions between large-scale spatial change and community-scale social justice. I explain how the imperatives of the Green New Deal, in conjunction with the shifting sites, scales, and politics of planning for climate change, should encourage planners to reframe their spaces and politics of practice toward a reconceptualized urban regional scale and a new politics of more public participation.     

Formation of Sn–Bi solder alloys by sequential electrodeposition and reflow

Eutectic Sn–Bi alloy is gaining considerable attention in the electronic packaging industry because of its favorable properties such as low melting temperature, good wettability, and good mechanical properties. Miniaturization of electronic devices requires small solder bumps, a few tens of micrometers in diameter. Electrodeposition is a reliable technique for the deposition of small volume of solder. This work focuses on the formation of eutectic Sn–Bi solder by reflowing a metal stack containing sequentially electrodeposited Sn and Bi layers. The effects of layering sequence on the composition and microstructure of the resulting alloy is investigated. Irrespective of the layering sequence, a homogeneous microstructure is achieved after reflow. The microstructure of the reflowed samples is the same as that of a metallurgically processed Sn–Bi alloy. Near-eutectic alloy with the composition Sn–54.6 wt% Bi is obtained by the sequential electrodeposition method.     

The Relationship between COVID-19 and Hypothalamic–Pituitary–Adrenal Axis: A Large Spectrum from Glucocorticoid Insufficiency to Excess—The CAPISCO International Expert Panel

Coronavirus disease 2019 (COVID-19) is a highly heterogeneous disease regarding severity, vulnerability to infection due to comorbidities, and treatment approaches. The hypothalamic–pituitary–adrenal (HPA) axis has been identified as one of the most critical endocrine targets of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that might significantly impact outcomes after infection. Herein we review the rationale for glucocorticoid use in the setting of COVID-19 and emphasize the need to have a low index of suspicion for glucocorticoid-induced adrenal insufficiency, adjusting for the glucocorticoid formulation used, dose, treatment duration, and underlying health problems. We also address several additional mechanisms that may cause HPA axis dysfunction, including critical illness-related corticosteroid insufficiency, the direct cytopathic impacts of SARS-CoV-2 infection on the adrenals, pituitary, and hypothalamus, immune-mediated inflammations, small vessel vasculitis, microthrombotic events, the resistance of cortisol receptors, and impaired post-receptor signaling, as well as the dissociation of ACTH and cortisol regulation. We also discuss the increased risk of infection and more severe illness in COVID-19 patients with pre-existing disorders of the HPA axis, from insufficiency to excess. These insights into the complex regulation of the HPA axis reveal how well the body performs in its adaptive survival mechanism during a severe infection, such as SARS-CoV-2, and how many parameters might disbalance the outcomes of this adaptation.     

Application of central composite design for optimization of bio-oil production using peat moss

Most nations have concentrated on reducing greenhouse gas emissions since global warming is such a serious problem. Due to land use changes, the harvesting of peat for use as fuel in homes, and the gardening industry, peat moss from peat bogs or peat fields may cause smoldering fires and release quantities of carbon dioxide. Bio-fuel is one of the alternative renewable sources created from organic materials. Pyrolysis, a thermochemical process that converts organic materials into substitutes for fossil fuels and used to create biofuel because it is readily available, straightforward, and inexpensive to implement. The feedstock utilized in this experiment was peat moss. Proximate and ultimate analyses were performed using thermogravimetric analysis and elemental analyzer to determine thermal breakdown and elemental characteristics. Pyrolysis was carried out in this work using a prototype lab scale fixed-bed pyrolysis. Based on prior study, the parameters used are pyrolysis temperature, nitrogen flow rate and reaction time to create the central composite design model. According to the analysis of variance results, pyrolysis temperature and flow rate were significant, however reaction time was not. The effect of flow rate and reaction time on response was explored. The actual bio-oil yield achieved utilizing the optimal parameters was 10.02 %. The presence of chemical compounds in bio-oil was measured.     

Thermal Performance Simulation of Eco-Friendly Lightweight Foamed Concrete Incorporating Palm Oil Fuel ash and Eggshell Powder Using ABAQUS

Silicon - The need for thermal insulating building material due to increase in Urban Heat Island effect and the carbon footprint associated with concrete due to its binder, cement, has caused...