Solubility of N2O and CO2 in n-Dodecane

The solubility of CO₂ and N₂O in a physical solvent, n-dodecane [C.A. Registry N° 124–18–5], has been measured at 40, 80 and 120°C at pressures up to 9.6 MPa. The experimental results were correlated by the Peng-Robinson (1976) equation of state, and the interaction parameters, the Henry's constants and the N₂O analogy parameters were obtained.     

MRI: A complementary tool for imaging cement pastes

This study examined the advantages and limitations of imaging cement paste with magnetic resonance imaging (MRI) using the single point imaging (SPI) sequence. Cement paste samples made with low water to cement (w/c) ratios were examined. The resolutions that could be attained in the images depended on the sizes of the samples. This technique, however, proved to be sensitive to water concentration gradients and allowed monitoring of water diffusion into the paste samples. In order to calibrate the features of the MR image, a comparison was made between electron micrographs and MR images of the same specimens. This revealed that the former could produce higher resolution images, however, considerable time was needed for sample preparation, the sample integrity was not guaranteed and only a small area of the sample could be viewed. In contrast, MRI offered in situ images which were three-dimensional and took less time to obtain than the electron micrographs but were of lower resolution. It is concluded that MRI could be a valuable tool for imaging cement pastes provided the features of the images have been “calibrated” by comparison with other, better known, techniques.     

Polyvinylidenefluoride/Poly(styrene-butadiene-styrene)/Silver Nanoparticle-grafted-Acid Chloride Functional MWCNTs-Based Nanocomposites: Preparation and Properties

A new type of nanofiltration membranes was synthesized using solution blending polyvinylidine fluoride (PVDF) and poly(styrene-butadiene-styrene) with acid chloride-modified multi-walled carbon nanotubes (MWNTs-COCl) and acid chloride-modified nanotbes-grafted-silver nanoparticles (MWNTs-COCl-Ag). SEM of PVDF/SBS-MWCNTs-COCl-Ag nanocomposite membranes showed polymer-coated Ag particles grafted on the surface. Tensile testing depicted the enhanced mechanical stability of PVDF/SBS-MWCNTs-COCl-Ag membranes around 18.8–22.4 MPa relative to PVDF/SBS-MWCNTs-COCl (10.1–13.3 MPa). 0.1 wt.% MWCNTs-COCl-Ag also enhanced the water permeability of membrane. Moreover, acid chloride-modified MWCNTs and Ag nanoparticles enhanced thermal properties to T₀ of 358°C, T₁₀ of 476°C and T_max around 599°C.     

Synthesis of BaWO4/NRGO‒g-C3N4 nanocomposites with excellent multifunctional catalytic performance via microwave approach

Novel barium tungstate/nitrogen-doped reduced graphene oxide?graphitic carbon nitride (BaWO₄/NRGO?g-C₃N₄) nanocomposite has been synthesized by a simple one-pot microwave technique. The synthesized nanocomposites are well characterized by diffraction, microscopic and spectroscopic techniques to study its crystal structure, elemental composition, morphological features and optical properties. The material prepared is tested for its performance as an electrocatalyst, photocatalyst and reduction catalyst. The nanocomposite catalyzed the photodegradation of methylene blue (MB) dye in 120 min, reduction of 4-nitro phenol (4-NP) to 4-amino phenol (4-AP) in 60 s, showed an impressive Tafel slope of 62 mV/dec for hydrogen evolution reaction (HER). The observed results suggest that the nanocomposite acts as an efficient multifunctional catalyst. The reported approach provides fundamental insights which can be extended to other metal tungstate-based ternary composites for applications in the field of clean energy and environment in the future.     

Histologic classification of ductal carcinoma in situ

Prior to the current mammographic era, ductal carcinoma in situ (DCIS) usually presented as a large mass, was classified morphologically by architecture, and treated by mastectomy. The introduction of screening mammography led to an increase in the incidence of DCIS, a decrease in the average size of DCIS, and an increased emphasis on its heterogeneous nature. Thus, a reproducible and prognostically relevant classification system for DCIS is necessary. The ultimate goal of this classification is proper selection of patients for whom lumpectomy would suffice rather than mastectomy. Features to evaluate include: extent and size of disease, adequacy of resection margins, and histology. While none of the proposed histological classification systems were endorsed at the recent Consensus Conference on the Classification of DCIS, nuclear grade was the most important feature common to most of them. Architecture was given secondary importance. By definition, DCIS is a non-invasive clonal proliferation of epithelial cells originating in the terminal duct lobular unit, which would be expected to be monomorphic; however, it is the degree of nuclear pleomorphism that is primarily used to separate DCIS into low, intermediate, and high grades. Architecturally, DCIS has been divided into the following types: comedo, solid, cribriform, micropapillary, and papillary. Different architectural patterns and grades may be present in a given particular case; however, some combinations of patterns occur more frequently than others. Interobserver studies have shown nuclear grading to be interpreted with greater consistency than architecture, and nuclear grading methods have correlated with biological and molecular marker studies.     

Experimental validation of numerical simulations of the kneading disc section in a twin screw extruder

A comparison of the results of a 3D model for the simulation of flow in the kneading disc region of a fully intermeshing twin screw extruder has been done against particle image velocimetry (PIV) experimental data. Experimental results using a geometry with an extended first and last kneading disc to capture the simplified inlet and outlet boundary conditions, are in good qualitative agreement for low flow rates. The results showed good agreement at flow rates less than 5 mL/s and rotation speeds of 60 rpm, while above that there was poor agreement. These results highlight the importance of the use of appropriate boundary conditions for the accurate prediction of the flow field. The flow field within the kneading discs with forward conveying elements placed before and after the kneading discs was also measured. For a flow rate of 8.5 mL/s and 60 rpm, results showed good agreement when conveying elements were deployed before and after the kneading blocks whereas for lower flow rates there was poor agreement.     

Adhesion, hardness and structure of thermal sprayed Al/SiC composite coat on graphite

Combustion powder spraying has been used in the coating of graphite by a layer of Al and SiC composite utilizing the Box-Wilson design that fixes the optimum spraying parameters of Al/SiC wt.% composition, substrate temperature and spraying distance. Graphite substrate surface was conditioned by subjecting to sand blast roughing and nitrogen flushed furnace treating. Under the spraying conditions considered, a single spraying pass attains a coating layer 65 ± 15 µm of average thickness. Two optimum spraying conditions that concern adhesion of coating to graphite and its hardness are obtained. Upon spraying for adhesion purpose, the coat/graphite adhesion strength is found to depend mainly on graphite surface conditioning, but for hardness purpose, it is found to depend mainly on SiC wt.% composition.Microstructure of transversal coating section indicates that adhesion efficiency is due to physical interlocking of molten sprayed materials on the roughened and treated graphite surface. Phases identified from fractured coatings by XRD analysis show individual phase of Al, SiC and graphite in addition to small amount of new extra phases that combine the three constituents such as Al₄C₃ and Al₄Si₂C₅. These phases play a role with the good physical interlocking in achieving adhesion strength that exceeds that of graphite.     

Sepiolite grafted polypyrrole: Influence of degree of grafting on structural,thermal, and impedance properties of nanohybrid

Conductive pyrrole monomer was grafted on vinyl modified sepiolite by surface initiated emulsion graft polymerization. Effect of process variables such as monomer, initiator, and surfactant on degree of grafting (%) were investigated. Maximum 745% degree of grafting was obtained at optimized grafting conditions. Structural changes in sepiolite by grafting of polypyrrole chains was confirmed by Fourier transform infrared spectroscopy and X-ray diffraction techniques. Surface morphology of the grafted nanohybrid was investigated by scanning electron microscopy (SEM). Thermal studies were carried out to acquire information concerning thermal stability of the synthesized materials and it was found increasing with the increase in grafting (%) of polypyrrole in sepiolite grafted polypyrrole (MS-g-PPy). Complex impedance spectroscopic analysis was carried out to study the effects of grafting of PPy on the ac electrical properties of synthesized nanohybrid composite at ambient temperature in the frequency range of 0.5–10⁷ Hz. The value of electrical conductivity was affected by degree of grafting (%) and maximum value of 0.85 × 10⁻⁴ S/cm was achieved. Both dielectric loss factor and permittivity increase with the decrease of frequency exhibiting strong interfacial polarization at low frequency.     

FTIR and thermodynamic study of Pakistani and international crude oils in 1,4-dioxane

This paper is the continuation of our previous paper, which concerned the viscosity of crude oils in 1,4-dioxane. In this paper, we present the Fourier Transform Infrared (FTIR) spectroscopy and thermodynamic study of Pakistani and International crude oils. Degree of branching, chain length, and degree of substitution in aromatic by FTIR data were calculated. Thermodynamic parameters viz., energy of activation (E_η), free energy change of activation (ΔG^*), latent heat of vaporization (L_v), and entropy change of activation (ΔS^*) have also been evaluated.     

Fabrication and evaluation studies of novel polyvinylpyrrolidone and 2-acrylamido-2-methylpropane sulphonic acid-based crosslinked matrices for controlled release of acyclovir

Polymer Bulletin - The aim of the present study was to fabricate chemically crosslinked matrix system of polyvinylpyrrolidone (PVP)-co-poly 2-acrylamido-2-methylpropane sulphonic acid (AMPS)...