Optical Spectroscopic Analysis of High Density Lead Borosilicate Glasses

Lead borosilicate glasses, of chemical composition 20SiO₂-xPbO-(15 + x)B₂O₃-5WO₂-10ZnO-(50-2x) Na₂O (where x = 5, 10, 15, 20, 25) were prepared using the normal melt-quenching technique. The samples were examined using a Philips Analytical X-ray diffraction system in order to check their amorphous nature. The effect of increasing B₂O₃ and PbO content on glass transition temperature was examined using Differential Thermal Analysis measurements (DTA). The results of DTA showed that both melting and glass transition temperatures decrease with increase of lead and boron oxides. Density and its related parameters have been determined to study the effect of lead-boron content on the structural properties of the prepared samples. Based on the density and DTA results, the network forming role of Pb and B ions was proved. The optical properties of the glass samples have been obtained using UV-VIS measurements. The optical parameters, such as optical band gap, Urbach energy, refractive index, and electronic polarizability were deduced based on the optical data. The observed increase in optical band gap and decrease in Urbach energy as well as the red shift in the absorption spectra arise due to the formation of non-bridging oxygen.     

Expression of DDX11 and DNM1L at the 12p11 Locus Modulates Systemic Lupus Erythematosus Susceptibility

Objectives: This study employed genetic and functional analyses using OASIS meta-analysis of multiple existing GWAS and gene-expression datasets to identify novel SLE genes. Methods: Four hundred and ten genes were mapped using SNIPPER to 30 SLE GWAS loci and investigated for expression in three SLE GEO-datasets and the Cordoba {"type":"entrez-geo","attrs":{"text":"GSE50395","term_id":"50395"}}GSE50395-dataset. Blood eQTL for significant SNPs in SLE loci and STRING for functional pathways of differentially expressed genes were used. Confirmatory qPCR on SLE monocytes was performed. The entire 12p11 locus was investigated for genetic association using two additional GWAS. Expression of 150 genes at this locus was assessed. Based on this significance, qPCRs for DNM1L and KRAS were performed. Results: Fifty genes were differentially expressed in at least two SLE GEO-datasets, with all probes directionally aligned. DDX11, an RNA helicase involved in genome stability, was downregulated in both GEO and Cordoba datasets. The most significant SNP, rs3741869 in OASIS locus 12p11.21, containing DDX11, was a cis-eQTL regulating DDX11 expression. DDX11 was found repressed. The entire 12p11 locus showed three association peaks. Gene expression in GEO datasets identified DNM1L and KRAS, besides DDX11. Confirmatory qPCR validated DNM1L as an SLE susceptibility gene. DDX11, DNM1L and KRAS interact with each other and multiple known SLE genes including STAT1/STAT4 and major components of IFN-dependent gene expression, and are responsible for signal transduction of cytokines, hormones, and growth-factors, deregulation of which is involved in SLE-development. Conclusion: A genomic convergence approach with OASIS analysis of multiple GWAS and expression datasets identified DDX11 and DNM1L as novel SLE-genes, the expression of which is altered in monocytes from SLE patients. This study lays the foundation for understanding the pathogenic involvement of DDX11 and DNM1L in SLE by identifying them using a systems-biology approach, while the 12p11 locus harboring these genes was previously missed by four independent GWAS.     

Utilization of ZSM-5/MCM-41 composite as FCC catalyst additive for enhancing propylene yield from VGO cracking

A micro-mesoporous ZSM-5/MCM-41 composite molecular sieve (ZM13) was synthesized and tested as an FCC catalyst additive to enhance the yield of propylene from catalytic cracking of vacuum gas oil (VGO). The catalytic performance of the additive was assessed using a commercial equilibrium USY FCC catalyst (E-Cat) in a fixed-bed micro-activity test unit (MAT) at 520?°C and various catalyst/oil ratios. MCM-41, ZSM-5 and two ZSM-5/MCM-41 composites were systematically characterized by complementary techniques such as XRD, BET, FTIR and SEM. The characterization results showed that the composites contained secondary building unit with different textural properties compared to pure ZSM-5 and MCM-41. MAT results showed that the VGO cracking activity of E-Cat did not decrease by using these additives. The highest propylene yield of 12.2 wt% was achieved over steamed ZSM-5/MCM-41 composite additive (ZM13) compared with 8.6 wt% over conventional ZSM-5 additive at similar gasoline yield penalty. The enhanced production of propylene over composite additive was attributed to its mesopores that suppressed secondary and hydrogen transfer reactions and offered easier transport and accessibility to active sites. Gasoline quality was improved by the use of all additives except MCM-41, as octane rating increased by 6?C12 numbers.     

Physical and mechanical properties of a poly-3-hydroxybutyrate-coated nanocrystalline hydroxyapatite scaffold for bone tissue engineering

A major challenge for tissue engineers is the design of scaffolds with appropriate physical and mechanical properties. The present research discusses the formation of ceramic scaffolding in tissue engineering. Hydroxyapatite (HAp) powder was made from bovine bone by thermal treatment at 900?°C; 40, 50 and 60%wt porous HAp was then produced using the polyurethane sponge replication method. Scaffolds were coated with poly-3-hydroxybutyrate (P3HB) for 30?s and 1?min in order to increase the scaffold??s mechanical properties. XRD, SEM and FT-IR were used to study phase structure, morphology and agent groups, respectively. In XRD and FT-IR data, established hydrogen bands between polymer and ceramic matrix confirm that the scaffold is formed as a composite. The scaffold obtained with 50%wt HAp and a 30?s coating was 90% porous, with an average diameter of 100?C400???m, and demonstrated a compressive strength and modulus of 1.46 and 21.27?MPa, respectively. Based on these results, this scaffold is optimised for the aforementioned properties and can be utilised in bone tissue engineering.     

AlBr3 impact on the thermal degradation of P(S-co-MMA): a study performed by contemporary techniques

Pyrolysis of copolymer, [P(S-co-MMA)], in the presence of AlBr₃ was inspected in an inert atmosphere. Five different proportions (copolymer/additive) were chosen. Films were cast from common solvent. It was noticed that copolymer showed more stability on the basis of T _0, however, regions of stability were also observed for the blends. Copolymer showed T ₀ at 260?°C, whereas blends started degrading around 70?°C. T _max was the same for the copolymer and the blends. Low-temperature decompositions of blends were attributed to the generation of free radicals (Br^?) and the zones of stabilizations were assigned to the formation of a ??complex type?? structure between Al and the carbonyl oxygens of MMA units. Degradation products were collected and identified employing Py-GC?CMS technique. Intermediates (solid) at different temperatures (300, 350 and 400?°C) were examined through FTIR spectroscopy. In the light of gathered data, a degradation mechanism was proposed. New products were encountered, viz., bromobenzene, ??brominated?? anhydride ring, etc., which established the chemical interactions between the constituents of the blends, i.e., copolymer and additive. Anhydride rings were absent when poly (methyl methacrylate) was pyrolyzed in the presence of AlBr₃. Oligomers of styrene were not found hinting at the involvement of additive in ??targeting?? the degrading styrene units. The blends indicate 2?C7% residue of original mass; the additive exhibits 9% while the copolymer does not leave residue at the completion of the TG run. The presence of char in the residues of blends suggests that the additive imparts stability to the copolymer. Horizontal burning rate was lowest (6 times less than that of neat copolymer) for [P(S-co-MMA):AlBr₃, 87.5:12.5%], thereby revealing the efficiency of the additive as thermal stabilizer. The highest activation energy was calculated for the copolymer (169.46?kJ/mol) and the range of this parameter for the blends was found from 52.72 to 27.14?kJ/mol.     

Modification of poly(propylene) by grafted polyester‐amide‐based dendritic nanostructures with the aim of improving its dyeability

Fiber‐graded poly(propylene) was modified by polyester‐amide‐based dendritic nanostructures with the aim of improving its dyeability. Two different dendritic polymers were used and the dendritic nanostructures were formed in situ via reactive blending with maleic anhydride‐modified poly(propylene). Samples were chosen exploiting a 4‐component mixture design. Thermal, morphological, and rheological characterizations showed domains with different size and distribution were formed and primary properties of the dendritics determined the characteristics of the resulted domains. Morphological parameters were quantified by digital analysis of scanning electron microscope images. Thermal and rheological behavior also demonstrated good agreements with the inferred morphology of the formed dendritic domains. The modified samples were then dyed with dispersed dyestuffs. A variety of substantivities were obtained, and some of the modified samples showed a significant enhancement in dyeing properties. A predictive model was developed for K/S ratio, where K and S are absorption and scattering coefficients of the Kubelka‐Munk one constant theory, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

<Emphasis Type="SmallCaps">l</Emphasis>-Aspartic acid incorporated optically active poly(amide-imide)s: synthesis and characterization

N-trimelliticimido-l-aspartic acid (1) was prepared from the reaction of trimellitic anhydride with l-aspartic acid in a mixture of glacial acetic acid and pyridine solution (3/2 ratio) under refluxing conditions. The solution polycondensation of the corresponding activated monomer with eight aromatic diamines were carried out in DMAc. The resulting poly(amide-imide)s were obtained in quantitative yields, showed admirable inherent viscosities (0.20–0.36 dl g⁻¹), good optical activity (+7.32o to +15.24o), and were readily soluble in polar aprotic solvents. They start to decompose (T _10%) above 170 °C and display glass-transition temperatures at 120–237 °C. All of the above polymers were fully characterized by UV, FT–IR, and ¹HNMR spectroscopy, elemental analysis, thermogravimetric analyses, DSC, inherent viscosity measurement, and specific rotation.     

Comparison of Canola and Soy Flour with Added Isocyanate as Wood Adhesives

Canola is widely grown in the northern latitudes for its vegetable oil, generating large quantities of residual, low value canola flour used as animal feed. The common wood adhesive poly(diphenylmethylene diisocyanate) (pMDI) should react with the wide variety of functional groups in proteins. Therefore, it would seem that canola flour with added pMDI could be an effective adhesive. Two main questions are addressed in this study: How do the wood adhesive properties of canola flour compare to the better-studied soy flour? How well do proteins, which contain an abundance of functional groups, cure with the very reactive pMDI? These questions were addressed using the small-scale adhesive strength test ASTM D-7998, with various adhesive formulations and bonding conditions for canola flour plus pMDI compared to soy adhesives. The more challenging wet cohesive bond strength was emphasized because the dry strengths were usually very good. Generally, soy adhesives were better than canola ones, as was the polyamidoamine-epichlorohydrin cross-linker compared to pMDI, but these generalizations can be altered by the conditions selected. Three-ply plywood tests supported the small-scale test results.     

In situ emulsion polymerization and characterization of PVAc nanocomposites including colloidal silica nanoparticles for wood specimens bonding

Polyvinyl acetate (PVAc) nanocomposites for wood adhesives containing different amounts of colloidal silica nanoparticles (CSNs) were synthesized via in situ one-step emulsion polymerization. The adhesion strength of wood specimens bonded by PVAc nanocomposites was investigated by the tensile test. Thermal properties of PVAc nanocomposites were also characterized by differential scanning calorimetry and thermogravimetric analysis. Rheological and morphological properties of the PVAc nanocomposites were investigated using rheometric mechanical spectrometry and field emission scanning electron microscopy (FESEM), respectively. The obtaining results showed that the shear strength of PVAc nanocomposite including 1 wt. % CSNs has the highest shear and tensile strength about 4.7 and 3.2 MPa, respectively. A small increment of T_g (~3 °C) and considerable increment of the ash content proved the enhancement of PVAc thermal characterization in the presence of CSNs. FESEM results showed uniform dispersion of nanoparticles throughout the PVAc matrix due to using the in situ emulsion polymerization process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48570.