β-Amyloid Targeting with Two-Dimensional Covalent Organic Frameworks: Multi-Scale In-Silico Dissection of Nano-Biointerface

Cytotoxic aggregation of misfolded β-amyloid (Aβ) proteins is the main culprit suspected to be behind the development of Alzheimer's disease (AD). In this study, Aβ interactions with the novel two-dimensional (2D) covalent organic frameworks (COFs) as therapeutic options for avoiding β-amyloid aggregation have been investigated. The results from multi-scale atomistic simulations suggest that amine-functionalized COFs with a large surface area (more than 1000 m²/gr) have the potential to prevent Aβ aggregation. Gibb's free energy analysis confirmed that COFs could prevent protofibril self-assembly in addition to inhibiting β-amyloid aggregation. Additionally, it was observed that the amine functional group and high contact area could improve the inhibitory effect of COFs on Aβ aggregation and enhance the diffusivity of COFs through the blood-brain barrier (BBB). In addition, microsecond coarse-grained (CG) simulations with three hundred amyloids reveal that the presence of COFs creates instability in the structure of amyloids and consequently prevents the fibrillation. These results suggest promising applications of engineered COFs in the treatment of AD and provide a new perspective on future experimental research.     

The Crystal Size Effect of Nano-Sized ZSM-5 in the Catalytic Performance of Petrochemical Processes: A Review

The ZSM-5 catalyst has received significant attention in recent years due to its significant properties such as strong acidity and high surface area. Crystal size of the catalyst has been recognized as an important factor in its performance. This review investigates the effects of the crystal size of ZSM-5 on its catalytic performance—selectivity; conversion; lifetime, product distribution; and coke formation during methanol to hydrocarbons (MTH), methanol to dimethyl ether, ethanol to gasoline (ETG), ethylene to gasoline (ETG), acetone to gasoline (ATG), acetone to olefin (ATO), naphtha cracking, and and n-dodecane cracking processes. This study demonstrates that the reduction of crystal size leads to higher levels of activity, conversion, and stability in these various processes.     

Investigation on local and average static hold‐ups in liquid–liquid systems in a rotary disc contactor

A rotating disc contactor with inner diameter of 91 mm and 21 compartments was used to investigate local and average static hold‐ups in the column. Three chemical systems, including distilled water as stagnant continuous phase and toluene, kerosene, and butyl acetate as dispersed phase, in case of no mass transfer, were applied. Different parameters consisting of drop size and static hold‐up were measured experimentally under various operating conditions, and two dimensionless correlations for estimation of local static hold‐up as a function of average mother drop size, physical properties, rotor speed, and stage number were proposed in two cases: (1) immovable and (2) rotating rotor discs. Furthermore, two dimensionless correlations were presented to estimate average static hold‐up as a function of average mother drop size, physical properties, rotor speed, and number of stages in the column in the two aforementioned conditions.     

Growth of the Dysprosium–Barium–Copper Oxide Superconductor Nanoclusters in Biopolymer Gels

Clusters of DyBa₂Cu₃O_7?y high T_C type II nanosuperconductor were prepared by sol–gel method in the presence of biopolymer chitosan. At the first step, the precursor and biopolymer were aggregated into amorphous matrix and then hydrogels were formed by thermogelling. Nucleation and growth of discrete nanoparticles is controlled by the biopolymer gel owing to retention of the fibrous nature of the chitosan at high temperatures up to 500?°C. After heating to 900?°C and complete decomposition of BaCO₃, nanoparticles of DyBa₂Cu₃O_7?y superconductor with diameter of 10–20?nm in the form of nanoclusters are prepared. Critical temperature (T_c) of the nanoparticles was found to be above 83?K. Characterizations of specimens were performed using scanning electron microscopy and transmission electron microscopy, supported by other techniques including XRD diffraction, energy dispersive X-ray, FT-IR spectrum and magnetic susceptibility measurements.     

Tunable optical,electronic and magnetic properties of semiconductor nanoparticles induced by magnetic and nonmagnetic dopants: A comparative experimental and theoretical study

While combining semiconductor and magnetic properties at the nanoscale provides dilute magnetic semiconductor (DMS) nanomaterials with a wide range of applications in next-generation electronic devices, tuning DMS properties still presents a challenge. Here, the synthesis of pure ZnO and transition metal (TM)-doped ZnO nanoparticles (NPs) with different magnetic (Fe and Co) and nonmagnetic (Mn) dopant concentrations (ranging from 2% to 10%) is reported using a co-precipitation method. Introducing the TM-dopants into ZnO NPs with 35?nm wurtzite structure causes crystallite and mean NP sizes to decrease, as characterized by X-ray diffraction and field-emission scanning electron microscopic analyses. Room-temperature magnetic measurements indicate coexistence of paramagnetic and ferromagnetic phases with tunability in the resulting TM-doped NPs. The maximum ferromagnetic coercivity and saturation magnetization are found to be 89?Oe and 0.074?emu/g for 10% Fe-doped ZnO NPs. UV–visible spectra showed a blue shift with increasing the dopant concentration, being in agreement with increasing trend in band gap energy calculated from band structure and density of state of TM-doped ZnO nanocrystal systems.     

Meta-analysis of cognitive-behavioral interventions on HIV-positive persons' mental health and immune functioning.

Objective: To evaluate the efficacy of cognitive-behavioral interventions (CBIs) for improving the mental health and immune functioning of people living with HIV (PLWH). Design: Comprehensive searches of electronic databases from 1988 to 2005, hand searches of journals, reference lists of articles, and contacts with researchers. Meta-analytic approaches were used in synthesizing findings. Main Outcome Measures: Intervention effects on symptoms of depression, anxiety, and anger, stress, and CD4 cell counts were assessed. Results: Data from 15 controlled trials were analyzed. Significant intervention effects were observed for improving symptoms of depression (d = 0.33), anxiety (d = 0.30), anger (d = 1.00), and stress (d = 0.43). There is limited evidence suggesting intervention effects on CD4 cell counts (d = 0.08). The aggregated effect size estimates for depression and anxiety were statistically significant in trials that provided stress management skills training and had more than 10 intervention sessions. Conclusion: CBIs are efficacious in improving various psychological states of PLWH. Future research should examine the relationship among interventions, psychological states, medication adherence, and immune functions, and identify other relevant factors associated with intervention effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nanosheets Based Approach to Elevate the Proliferative and Differentiation Efficacy of Human Wharton’s Jelly Mesenchymal Stem Cells

Mesenchymal stem cell (MSC)-based therapy and tissue repair necessitate the use of an ideal clinical biomaterial capable of increasing cell proliferation and differentiation. Recently, MXenes 2D nanomaterials have shown remarkable potential for improving the functional properties of MSCs. In the present study, we elucidated the potential of Ti₂CTx MXene as a biomaterial through its primary biological response to human Wharton’s Jelly MSCs (hWJ-MSCs). A Ti₂CTx nanosheet was synthesized and thoroughly characterized using various microscopic and spectroscopic tools. Our findings suggest that Ti₂CTx MXene nanosheet exposure does not alter the morphology of the hWJ-MSCs; however, it causes a dose-dependent (10–200 µg/mL) increase in cell proliferation, and upon using it with conditional media, it also enhanced its tri-lineage differentiation potential, which is a novel finding of our study. A two-fold increase in cell viability was also noticed at the highest tested dose of the nanosheet. The treated hWJ-MSCs showed no sign of cellular stress or toxicity. Taken together, these findings suggest that the Ti₂CTx MXene nanosheet is capable of augmenting the proliferation and differentiation potential of the cells.