Confinement, composition, and spin-coating effects on the glass transition and stress relaxation of thin films of polystyrene and styrene-containing random copolymers: Sensing by intrinsic fluorescence

The glass transition temperatures (T_gs) of polystyrene (PS) and styrene/methyl methacrylate (S/MMA) random copolymer films are characterized by intrinsic fluorescence, i.e., monomer fluorescence from an excited-state phenyl ring and excimer fluorescence from an excited-state dimer of two phenyl rings. The T_g is determined from the intersection of the rubbery- and glassy-state temperature dependences of the integrated fluorescence intensity measured upon cooling from an equilibrated state. With PS, the effects of nanoconfinement on T_g and the transition strength agree with results from studies using probe fluorescence and ellipsometry. The T_g-nanoconfinement effect is “tuned” by copolymer composition. As S-content is reduced from 100 mol% to 22 mol%, the confinement effect changes from a reduction to an enhancement of T_g relative to bulk T_g. Intrinsic fluorescence is also a powerful tool for characterizing relaxation of residual stresses. Stresses induced by spin coating affect local conformations, which in turn affect excimer and monomer fluorescence and thereby integrated intensity. The heating protocol needed to achieve apparently equilibrated local conformations is determined by equivalence in the integrated intensities obtained upon heating and subsequent cooling. While partial stress relaxation occurs upon heating in the glassy state, full relaxation of local conformations requires that a film be heated above T_g for times that are long relative to the average cooperative segmental relaxation time. For example, in thin and ultrathin films, equilibration is achieved by heating slowly (∼1 K/min) to 15-20 K above T_g. Dilute solution fluorescence of PS and S/MMA copolymers is also characterized and compared to reports in the literature.     

Mechanisms of passivation and chloride-induced corrosion of mild steel in sulfide-containing alkaline solutions

Journal of Materials Science - The pore fluid within many concretes is highly alkaline and rich in reduced sulfur species, but the influence of such alkaline-sulfide solutions on the surface film...     

An environmentally sustainable manufacturing network model under an international ecosystem

Clean Technologies and Environmental Policy - There is a growing consensus that the increase in greenhouse gases results in unfavorable changes to the Earth’s climate and is responsible for...     

The Lithiation Reactivity and Selectivity of Differentially Branched Alkyldiphenylphosphine Oxides – A Simple and Versatile Approach to ortho‐Functionalized Arylphosphine Oxides

Alkyldiphenylphosphine oxides typically undergo α‐deprotonation with alkyllithium reagents. Here, the lithiation of differentially branched alkyldiphenylphosphine oxides was investigated and a diverse, but predictable reactivity was found. γ‐Branched derivatives undergo selective directed ortho‐metalation (DoM) using butyllithium and TMEDA as an additive. With decreasing degree of γ‐branching α‐lithiation becomes predominant. The ortho‐phosphinoyllithium intermediates are subject to functionalization and C C bond forming reactions, thus providing a convenient approach to new phosphine oxides and phosphine‐borane complexes, which have a good potential for an approach to new ligands for catalysis.

     

Low-fat sweet syrup cheese ball (Rosogolla) manufacturing and effect of lowering fat on quality

Low-fat sweet syrup cheese ball (Rosogolla) was manufactured by using low-fat cow milk and implementing six different combinations viz. type of chhana and two different concentrations (40 and 50o Brix) of cooking medium. Experimental Rosogolla samples and control were analysed for physico-chemical, textural and sensory properties. A 40o Brix concentration of sugar syrup as a cooking medium gave a highly acceptable low-fat Rosogolla. Average composition of low-fat Rosogolla is, moisture—49.83%, fat—4.66%, protein—11.85%, sorbitol—32.41% and ash—0.90%. Rheological properties of the most acceptable low-fat Rosogolla were hardness—6.78 N, springiness—5.72 mm, gumminess—3.2 N, chewiness—18.92 Nmm and stiffness—0.95 N/mm.     

Calculation of weld metal composition change in high-power conduction mode carbon dioxide laser-welded stainless steels

The use of high-power density laser beam for welding of many important alloys often leads to appreciable changes in the composition and properties of the weld metal. The main difficulties in the estimation of laser-induced vaporization rates and the resulting composition changes are the determination of the vapor condensation rates and the incorporation of the effect of the welding plasma in suppressing vaporization rates. In this article, a model is presented to predict the weld metal composition change during laser welding. The velocity and temperature fields in the weld pool are simulated through numerical solution of the Navier-Stokes equation and the equation of conservation of energy. The computed temperature fields are coupled with ve-locity distribution functions of the vapor molecules and the equations of conservation of mass, momentum, and the translational kinetic energy in the gas phase for the calculation of the evap-oration and the condensation rates. Results of carefully controlled physical modeling experi-ments are utilized to include the effect of plasma on the metal vaporization rate. The predicted area of cross section and the rates of vaporization are then used to compute the resulting com-position change. The calculated vaporization rates and the weld metal composition change for the welding of high-manganese 201 stainless steels are found to be in fair agreement with the corresponding experimental results.     

Design of nanocarriers for efficient cellular uptake and endosomal release of small molecule and nucleic acid drugs: learning from virus

There are many challenges in developing efficient and target specific delivery systems of small molecule and nucleic acid drugs. Cell membrane presents one of the major barriers for the penetration of hydrophilic macromolecules across the plasma membrane. Nanocarriers have been designed to enhance their cellular uptake via endocytosis but following their cellular uptake, endosomal escape is the rate limiting step which restricts the value associated with the enhanced uptake by nanocarriers. Viruses are an excellent model for efficient cytosolic delivery by nanocarriers. Viruses exploit intracellular cues to release the genome to cytosol. In this review, we first discuss different endocytic uptake pathways and endosomal escape mechanisms. We then summarize the existing tools for studying the intracellular trafficking of nanocarriers. Finally, we highlight the important design elements of recent virus-based nanocarriers for efficient cellular uptake and endosomal escape.     

Fabrication of Food Grade Vitamin E Nanoemulsion by Low Energy Approach,Characterization and Its Application

The present study was carried out to fabricate the food grade vitamin E acetate nanoemulsion using edible mustard oil and to evaluate its improved bioactivities. A food-grade vitamin E acetate nanoemulsion was fabricated using the edible mustard oil and surfactant Tween-80. Flocculation was not observed for 15 days. The nanoemulsion was characterized for droplet morphology and size distribution using atomic force microscope and zetasizer, respectively. We observe a stable nanoemulsion of spherical morphology and a size distribution of 86.45 ± 3.61 nm. Further, the high-performance liquid chromatography method was used to determine the vitamin E acetate concentration and encapsulation efficiency for the stable nanoemulsion. These nanoemulsions showed improved bioactivity, antioxidant, and antimicrobial activity and could be potentially used to increase the shelf life of fruit juice.     

Controlled Release of a Dual Zinc-Sensing and Gene Regulating Small Molecule from DNA Micelles

Intracellular zinc ions are essential for various biological cell processes and are often dysregulated in many diseases de-pending on their location, protein binding affinity, and concentration in the cell. Due to their prevalence in diseases, it is important to not only effectively sense but chelate the often excess amount of zinc in a cell to alleviate further disease progression. N, N, N′, N′-tetrakis (2-pyridinylmethyl)-1,2-ethanediamine (TPEN) is a selective zinc chelator but its water-insoluble nature and general cytotoxicity limit its therapeutic potential. To address these challenges, TPEN loaded nucleic acid nanocapsules (TL-NANs) were synthesized, and its dual ability to sense and suppress zinc levels intracellularly were evaluated. Additionally, TL-NANs were incubated in lung cells and shown to down regulate Eotaxin, a protein up-regulated during asthma, at significantly reduced concentrations of TPEN showcasing the therapeutic potential of this drug for asthma.     

Computational Investigation Identified Potential Chemical Scaffolds for Heparanase as Anticancer Therapeutics

Heparanase (Hpse) is an endo-β-D-glucuronidase capable of cleaving heparan sulfate side chains. Its upregulated expression is implicated in tumor growth, metastasis and angiogenesis, thus making it an attractive target in cancer therapeutics. Currently, a few small molecule inhibitors have been reported to inhibit Hpse, with promising oral administration and pharmacokinetic (PK) properties. In the present study, a ligand-based pharmacophore model was generated from a dataset of well-known active small molecule Hpse inhibitors which were observed to display favorable PK properties. The compounds from the InterBioScreen database of natural (69,034) and synthetic (195,469) molecules were first filtered for their drug-likeness and the pharmacophore model was used to screen the drug-like database. The compounds acquired from screening were subjected to molecular docking with Heparanase, where two molecules used in pharmacophore generation were used as reference. From the docking analysis, 33 compounds displayed higher docking scores than the reference and favorable interactions with the catalytic residues. Complex interactions were further evaluated by molecular dynamics simulations to assess their stability over a period of 50 ns. Furthermore, the binding free energies of the 33 compounds revealed 2 natural and 2 synthetic compounds, with better binding affinities than reference molecules, and were, therefore, deemed as hits. The hit compounds presented from this in silico investigation could act as potent Heparanase inhibitors and further serve as lead scaffolds to develop compounds targeting Heparanase upregulation in cancer.