Type-II p–n junction three-dimensional Ag2O/TiO2 microspheres have been fabricated by assembling p-type Ag2O nanoparticle on n-type TiO2 3D microsphere. Ag2O/TiO2 microsphere nanoheterojunctions were ...obtained by hydrothermal synthesis of TiO2 microspheres at 180 °C followed by photoreduction of AgNO3. The samples were carefully characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis (EDX). The photocatalytic activity toward degradation of methyl orange (MO) aqueous solution under UV light was investigated. The result showed that type-II p–n nanoheterojunctions Ag2O/TiO2 significantly enhanced the photocatalytic degradation compared to n-type TiO2 microsphere. It was found that the photocatalytic degradation followed the pseudo first-order reaction model. In particular, heterostructure with molar ratio of TiO2 and AgNO3 of 4:1 exhibited best photocatalytic activity and the corresponding apparent first-order rate constant of 0.138 min–1 which is 4 times than that of pure n-type microsphere.
Ab initio first-principles calculations were carried out to investigate lithium-dispersed two-dimensional carbon allotropes, viz. graphyne and graphdiyne, for their applications as lithium storage ...and hydrogen storage materials. The lithiation potentials (vs Li/Li+) and specific capacities in these materials are found to be enhanced considerably as compared to the conventional graphite-based electrode materials. Lithium metal binding to these carbon materials is found to be enhanced considerably and is more than the cohesive energy of lithium. Each lithium atom in these metal-dispersed materials is found to carry nearly one unit positive charge and bind molecular hydrogen with considerably improved adsorption energies. Our calculated hydrogen adsorption enthalpies (−3.5 to −2.8 kcal/mol) are very close to the optimum adsorption enthalpy proposed for ambient temperature hydrogen storage (−3.6 kcal/mol). We have also shown that the band gaps in these planar carbon allotropes can be tuned by varying the number of acetylenic bridging units which will have versatile applications in nanoelectronics.
BACE1 (β-secretase, memapsin 2, Asp2) has emerged as a promising target for the treatment of Alzheimer's disease. BACE1 is an aspartic protease which functions in the first step of the pathway ...leading to the production and deposition of amyloid-β peptide (Aβ). Its gene deletion showed only mild phenotypes. BACE1 inhibition has direct implications in the Alzheimer's disease pathology without largely affecting viability. However, inhibiting BACE1 selectively in vivo has presented many challenges to medicinal chemists. Since its identification in 2000, inhibitors covering many different structural classes have been designed and developed. These inhibitors can be largely classified as either peptidomimetic or non-peptidic inhibitors. Progress in these fields resulted in inhibitors that contain many targeted drug-like characteristics. In this review, we describe structure-based design strategies and evolution of a wide range of BACE1 inhibitors including compounds that have been shown to reduce brain Aβ, rescue the cognitive decline in transgenic AD mice and inhibitor drug candidates that are currently in clinical trials.
Conspectus Metal–organic frameworks (MOFs) have evolved to be next-generation utility materials because of their serviceability in a wide variety of applications. Built from organic ligands with ...multiple binding sites in conjunction with metal ions/clusters, these materials have found profound advantages over their other congeners in the domain of porous materials. The plethora of applications that these materials encompass has motivated material chemists to develop such novel materials, and the catalogue of MOFs is thus ever-escalating. One key feature that MOFs possess is their responsiveness toward incoming guest molecules, resulting in changes in their physical and chemical properties. Such uniqueness generally arises owing to the influenceable ligands and/or metal units that govern the formation of these ordered architectures. The suitable host–guest interactions play an important role in determining the specific responses of these materials and thus find important applications in sensing, catalysis, separation, conduction, etc. In this Account, we focus on the two most relevant applications based on the host–guest interactions that are carried out in our lab, viz., separation and sensing of small molecules. Separation of liquid-phase aromatic hydrocarbons by less energy-intensive adsorption processes has gained attention recently. Because of their tailored structures and functionalized pore surfaces, MOFs have become vital candidates in molecular separation. Prefunctionalization of MOFs by astute choice of ligands and/or metal centers results in targeted separation processes in which the molecular sieving effect plays a crucial role. In this view, separation of C6 and C8 liquid aromatic hydrocarbons, which are essential feedstock in various chemical industries, is one area of research that requires significant attention because of the gruesome separation techniques adopted in such industries. Also, from the environmental perspective, separation of oil/water mixtures demands significant attention because of the hazards of marine oil spillage. We have achieved successful separation of such by careful impregnation of hydrophobic moieties inside the nanochannels of MOFs, resulting in unprecedented efficiency in oil/water separation. Also, recognition of small molecules using optical methods (fluorescence, UV, etc.) has been extended to achieve sensing of various neutral species and anions that are important from environmental point of view. Incorporation of secondary functional groups has been utilized to sense nitroaromatic compounds (NACs) and other small molecules such as H2S, NO, and aromatic phenols. We have also utilized the postfunctionalization strategy via ion exchange to fabricate MOFs for sensing of environmentally toxic and perilous anionic species such as CN– and oxoanions. Our current endeavors to explore the applicability of MOFs in these two significant areas have widened the scope of research, and attempts to fabricate MOFs for real-time applications are underway.
HIV-1 protease inhibitors continue to play an important role in the treatment of HIV/AIDS, transforming this deadly ailment into a more manageable chronic infection. Over the years, intensive ...research has led to a variety of approved protease inhibitors for the treatment of HIV/AIDS. In this review, we outline current drug design and medicinal chemistry efforts toward the development of next-generation protease inhibitors beyond the currently approved drugs.
Organic solar cells (OSCs) are promising for low emissive photovoltaic technology. Excitonic absorption and charge generation to transport process OSC energy loss lessening are central. In this ...context, donor–acceptor barrier offset, related binding, and thermal effect on energy loss are the key challenge. Semitransparent organic solar cell visible band transmission and near infrared band absorption are anticipated. Near infrared band absorption in a Si material solar cell is higher that supports more energy conversion. Moreover, greater carrier selectivity and open circuit voltage (Voc) is incredible to increase the energy efficiency. OSC utmost absorption but carrier generation and charge transfer state donor–acceptor barrier offset increases carrier recombination loss. Upon analysis of small molecule donors and polymers along with non-fullerene and previously studied fullerene acceptors, it is realized that active material morphology, thickness, and interface design are impending to overcome the energy loss. For efficiency–transparency trade-off as well as stability problem lessening purpose thin active materials and interface, their absorption band tenability and carrier selectivity are main requisites. In this scope, very thin non-fullerene acceptors in ternary blend heterostructures and innovative-transparent hole transport layers can play a vital role. Therefore, recombination loss lessening and transparency purpose near infrared band absorbent thin active layer ternary blend and transparent electrodes of a thin hetero-interface predominant field effect over the thermal effect are reported in the efficiency and stability scope.
The 3D organization of chromosomes is crucial for regulating gene expression and cell function. Many experimental and polymer modeling efforts are dedicated to deciphering the mechanistic principles ...behind chromosome folding. Chromosomes are long and densely packed-topologically constrained-polymers. The main challenges are therefore to develop adequate models and simulation methods to investigate properly the multi spatio-temporal scales of such macromolecules. Here, we proposed a generic strategy to develop efficient coarse-grained models for self-avoiding polymers on a lattice. Accounting accurately for the polymer entanglement length and the volumic density, we show that our simulation scheme not only captures the steady-state structural and dynamical properties of the system but also tracks the same dynamics at different coarse-graining. This strategy allows a strong power-law gain in numerical efficiency and offers a systematic way to define reliable coarse-grained null models for chromosomes and to go beyond the current limitations by studying long chromosomes during an extended time period with good statistics. We use our formalism to investigate in details the time evolution of the 3D organization of chromosome 3R (20 Mbp) in drosophila during one cell cycle (20 hours). We show that a combination of our coarse-graining strategy with a one-parameter block copolymer model integrating epigenomic-driven interactions quantitatively reproduce experimental data at the chromosome-scale and predict that chromatin motion is very dynamic during the cell cycle.
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