Molecular dynamic simulation studies of adsorption and diffusion behaviors of methanol and ethanol through ZSM-5 zeolite.

Due to the importance of synthesis gas's entire conversion to methanol, the separation of methanol from unconverted synthesis gas is an industrial challenge. In this work, the influence of temperature, guest molecules concentrations (methanol and ethanol), and acid site density (Si/Al) of zeolites on the diffusion of methanol and ethanol, pure and binary mixture (80% methanol and 20% ethanol) in silicalite-1 and HZSM-5 (Si/Al = 47 and 23) were studied by using of the COMPASS force-field molecular dynamics method. Also, the adsorption of pure methanol and ethanol and binary mixture through these zeolites has been studied by using the Grand Canonical Monte Carlo (GCMC) method. The calculated adsorption rate and isosteric heat of adsorption for ethanol are lower and higher than methanol, respectively. The results of the binary mixture show that HZSM-5 (Si/Al = 23) has the lowest adsorption selectivity and most diffusion selectivity. The calculated diffusion coefficients of methanol and ethanol guest molecules decreased with rising guest molecule concentration and Si/Al-ratios. The effect of both agents was investigated by analysis of mean square displacement (MSD) and RDF diagram.

Function of arteries and veins in conditions of simulated cardiac arrest.

Introduction: The study examined the behavior of vasculature in conditions of eliminated cardiac function using mathematical modeling. In addition, we addressed the question of whether the stretch-recoil capability of veins, at least in part accounts for the slower response to simulated cardiac arrest. Methods: In the first set of computational experiments, blood flow and pressure patterns in veins and arteries during the first few seconds after cardiac arrest were assessed via a validated multi-scale mathematical model of the whole cardiovascular system, comprising cardiac dynamics, arterial and venous blood flow dynamics, and microcirculation. In the second set of experiments, the effects of stretch-recoil zones of venous vessels with different diameters and velocities on blood velocity and dynamic pressure analyzed using computational fluid dynamics (CFD) modeling. Results: In the first set of experiments, measurement of changes in velocity, dynamic pressure, and fluid flow revealed that the venous system responded to cardiac arrest more slowly compared to the arteries. This disparity might be due to the intrinsic characteristics of the venous system, including stretch-recoil and elastic fiber composition. In the second set of experiments, we attempted to determine the role of the stretch-recoil capability of veins in the slower response to cardiac arrest. During the second set of experiments, we found that this recoil behavior increased dynamic pressure, velocity, and blood flow. The enhancement in dynamic pressure through combining the results from both experiments yielded a 15-40% increase in maximum dynamic pressure due to stretch-recoil, depending on vein diameter under normal conditions. Conclusion: In the situation of cardiac arrest, the vein geometry changes continue, promoting smooth responses of the venous system. Moreover, the importance of such vein behavior in blood displacement may grow as the pressure on the venous side gradually decreases with time. Our experiments suggest that the driving force for venous return is the pressure difference that remains within the venous system after the energy coming from every ventricular systole spent to overcome the resistance created by arterial and capillary systems.

Interdependency of influential parameters in therapeutic nanomedicine.

Introduction:Current challenges to successful clinical translation of therapeutic nanomedicine have discouraged many stakeholders, including patients. Significant effort has been devoted to uncovering the reasons behind the less-than-expected success, beyond failures or ineffectiveness, of therapeutic nanomedicine products (e.g. cancer nanomedicine). Until we understand and address the factors that limit the safety and efficacy of NPs, both individually and in combination, successful clinical development will lag.Areas covered:This review highlights the critical roles of interdependent factors affecting the safety and therapeutic efficacy of therapeutic NPs for drug delivery applications.Expert opinion:Deep analysis of the current nanomedical literature reveals ahistory of unanticipated complexity by awide range of stakeholders including researchers. In the manufacture of nanomedicines themselves, there have been persistent difficulties with reproducibility and batch-to-batch variation. The unanticipated complexity and interdependency of nano-bio parameters has delayed our recognition of important factors affecting the safety and therapeutic efficacy of nanomedicine products. These missteps have had many factors including our lack of understanding of the interdependency of various factors affecting the biological identity and fate of NPs and biased interpretation of data. All these issues could raise significant concern regarding the reproducibility- or even the validity- of past publications that in turn formed the basis of many clinical trials of therapeutic nanomedicines. Therefore, the individual and combined effects of previously overlooked factors on the safety and therapeutic efficacy of NPs need to be fully considered in nanomedicine reports and product development.

Nanoscale Technologies for Prevention and Treatment of Heart Failure: Challenges and Opportunities.

The adult myocardium has a limited regenerative capacity following heart injury, and the lost cells are primarily replaced by fibrotic scar tissue. Suboptimal efficiency of current clinical therapies to resurrect the infarcted heart results in injured heart enlargement and remodeling to maintain its physiological functions. These remodeling processes ultimately leads to ischemic cardiomyopathy and heart failure (HF). Recent therapeutic approaches (e.g., regenerative and nanomedicine) have shown promise to prevent HF postmyocardial infarction in animal models. However, these preclinical, clinical, and technological advancements have yet to yield substantial enhancements in the survival rate and quality of life of patients with severe ischemic injuries. This could be attributed largely to the considerable gap in knowledge between clinicians and nanobioengineers. Development of highly effective cardiac regenerative therapies requires connecting and coordinating multiple fields, including cardiology, cellular and molecular biology, biochemistry and chemistry, and mechanical and materials sciences, among others. This review is particularly intended to bridge the knowledge gap between cardiologists and regenerative nanomedicine experts. Establishing this multidisciplinary knowledge base may help pave the way for developing novel, safer, and more effective approaches that will enable the medical community to reduce morbidity and mortality in HF patients.

Probing fibronectin conformation on a protein corona layer around nanoparticles.

Protein unfolding induced by nanoparticles (NPs) can lead to exposure of cryptic epitopes that might dictate biological identity and affect NP biological fate (e.g., blood circulation time, biodistribution, and tumor accumulation). Here, we monitor the conformation of fluorescence resonance energy transfer (FRET)-labelled fibronectin (FN) on corona-coated gold NPs. We found that the labelled FN proteins, which directly accessed the gold NP surface, underwent more pronounced conformational changes than those associated with the protein corona via protein-protein interactions. FRET and liquid chromatography-mass spectrometry analyses demonstrated that NP size/concentration, pH change, and the level of surface coverage by the corona can tune the accessibility of labelled FN to the gold NP surface. Although some subsequently adsorbing proteins accessed the NP surface thanks to incomplete surface coverage and protein exchange (the Vroman effect), most outer-layer proteins could not directly bind to the NP surface, blocked by pre-adsorbed corona layers. This finding was also partially confirmed by isothermal titration calorimetry (ITC) analysis. These results suggest the proof-of-concept that outermost-layer proteins with modestly changed conformation rather than unfolded proteins at the gold NP surface effectively create the NPs' biological identity, which might have important implications on biological fates of gold NPs.