Fluxional behavior in dimeric tetraorganodicarboxylato stannoxanes

The mechanism of the fluxional process occurring in dimeric tetraorganodicarboxylato stannoxanes is presented on the basis of multinuclear NMR studies carried out in noncoordinating solvents. This fluxional process is a consequence of rapid migration of carboxylate groups from one tin atom to the other. It has been proposed that larger carboxylates will also execute this behavior. The effect of cis and trans positions on the fluxional process is discussed. The fluxional process is very fast and could not be stopped even at low temperatures, as measured on the NMR time scale. © 1996 John Wiley & Sons, Inc.     

Optimization of Graphene Layers Grown on Pt/Ti/SiO2 by Hot Filament Chemical Vapor Deposition

Large area single and bilayer graphene are grown on Pt/Ti/SiO₂ substrates by hot filament chemical vapor deposition (HFCVD) with and without the assistance of Cu foil. The quality and number of graphene layers deposited on the substrate are assessed by Raman Spectroscopy. Atomic Force Microscopy (AFM) is used for assessing the surface topography of the graphene films grown on the Pt/Ti/SiO₂ substrates. The microstructure and elemental analyses are performed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The results show that bilayer graphene growth is facilitated by a copper foil placed nearby Pt/Ti/SiO2 substrate and by a high filament temperature in the HFCVD reactor. Monolayer graphene grows only when no copper foil is placed near the Pt/Ti/SiO₂ substrate at a low filament temperature. The approach paves a novel pathway towards the layer-controlled growth of graphene on Pt/Ti/SiO₂ substrates by HFCVD for frontier applications.     

Ultrafiltration polyanionic poly (3-sulfopropyl methacrylate) membranes with enhanced antifouling and water flux

Polyethersulfone (PES) membranes are prevalent in the field of water treatment owing to their exceptional separation efficiency, robust mechanical properties, and resistance to chemical degradation. Nevertheless, these membranes are prone to fouling, resulting in a decrease in both flux and ultrafiltration efficiency. In the present study, PES membranes are blended with poly (3-Sulfopropyl Methacrylate) (PSPMA) in various weight percentages (0%–3%) to improve their antifouling and ultrafiltration properties. The physicochemical properties of the blended membranes, including surface morphology, contact angle, hydrophilicity and surface energy are evaluated. The findings indicate that incorporation PSPMA results in an enhancement of the hydrophilic properties and surface charge of the PES membranes, assessed by employing Bovine Serum Albumin (BSA) as a representative protein. Modified blended membranes display greater Flux Recovery Ratio (FRR%) and exhibit superior fouling resistance. Under the same experimental conditions (0.2 MPa applied pressure), a pure water flux of 154.18 L·m⁻²·h⁻¹ for PES/PSPMA membrane found substantially greater than pure PES membrane (103.52 L·m⁻²·h⁻¹) along with Total Fouling Ratio (TFR) of 36% and 64.9% respectively. Exceptional antimicrobial efficacy for modified membranes is revealed against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) using disc diffusion technique rendering them well-suited for water treatment applications.     

Static anti-windup compensator design for nonlinear time-delay systems subjected to input saturation

Nonlinear Dynamics - In this paper, a novel technique for synthesizing static anti-windup compensator (AWC) is explored for dynamic nonlinear plants with state interval time-delays, exogenous input...     

Structure engineering of small molecules for organic solar cells

Abstract

Two 1,3-bis(thiophen-2-yl)?5,7-bis(2-ehtylhexyl)benzo-[1,2-c:4,5-c]-dithiophene-4,8-dione (BDD) based small molecules, SM1 and SM2 are designed and synthesized by incorporating benzodithiophene (BDT) central core, BDD dual accepting units and 3-ethyl rhodamine as endcap group with various number of BDT units. We systematically investigated the synthesis, optical and electrochemical properties, and photovoltaic characteristics of these donor materials. The number of BDT units have a significant influence on Jsc due to interconnected structure and results in a broader absorption on thin film. The inverted devices employed for both small molecules exhibited power conversion efficiencies of 0.41% for SM1 and 0.82% for SM2.     

Linking Morphology of Porous Media to Their Macroscopic Permeability by Deep Learning

Flow, transport, mechanical, and fracture properties of porous media depend on their morphology and are usually estimated by experimental and/or computational methods. The precision of the computational approaches depends on the accuracy of the model that represents the morphology. If high accuracy is required, the computations and even experiments can be quite time-consuming. At the same time, linking the morphology directly to the permeability, as well as other important flow and transport properties, has been a long-standing problem. In this paper, we develop a new network that utilizes a deep learning (DL) algorithm to link the morphology of porous media to their permeability. The network is neither a purely traditional artificial neural network (ANN), nor is it a purely DL algorithm, but, rather, it is a hybrid of both. The input data include three-dimensional images of sandstones, hundreds of their stochastic realizations generated by a reconstruction method, and synthetic unconsolidated porous media produced by a Boolean method. To develop the network, we first extract important features of the images using a DL algorithm and then feed them to an ANN to estimate the permeabilities. We demonstrate that the network is successfully trained, such that it can develop accurate correlations between the morphology of porous media and their effective permeability. The high accuracy of the network is demonstrated by its predictions for the permeability of a variety of porous media.

     

Structure Determination of Cellulose Esters via Subsequent Functionalization and NMR Spectroscopy

New paths for the fast and reliable analysis of cellulose esters (CE) via subsequent functionalization and ¹H NMR spectroscopy were studied. Perpropionylation of the CE is an inexpensive and efficient method. For cellulose diacetates used as representative ester well resolved ¹H NMR spectra were obtained, which can be used for the calculation of the over all degree of substitution (DS) and the partial DS values at position 2, 3, and 6. No transesterification occurs during the subsequent acylation and a standard deviation of S² = 1.32 x 10⁻⁴ was found for a series of experiments. In case of more complex ester structures especially with extended aliphatic moieties per-4-nitrobenzoylation need to be applied prior to NMR measurements. The spectra obtained can be completely assigned and applied for the calculation of DS values.     

Hyperon-Neutron Elastic Scattering

It is shown that the Chou-Yang model can be extended to hyperon-neutron elastic reactions at high energies by assuming that the hadronic form factor of neutron is proportional to its magnetic form factor. It is also predicted that the scaling of magnetic form factor of neutron with charge as well as magnetic form factors of proton implies that the differential cross sections of corresponding hyperon-proton and hyperon-neutron reactions should be equal.     

Cavity dynamics of water drop impact onto immiscible oil pool with different viscosity

Acta Mechanica Sinica - In this work, we numerically study the impact of a water droplet onto a deep oil pool. Two fluids are immiscible and the viscosity of the pool liquid is changed...