Moderate concentration of citric acid for the formation of LaMnO3 and LaCoO3 nano-perovskites

Stoichiometric LaMnO3 and LaCoO3 nanoparticles were synthesized via calcination of a dried solution, containing molar ratio of La(NO3)3·6H2O/[Mn(NO3)2·4H2O or Co(NO3)2·6H2O]=1 and citric acid as disper...     

Investigating the microstructure and composition of cold gas-dynamic spray (CGDS) Ti powder deposited on Al 6063 substrate

The compositional variation, morphology and microstructure of cold gas-dynamic spray are of great importance for its proper application. This study investigates titanium powder deposition on an Al 6063 substrate using light optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composition was examined using energy dispersive X-ray spectroscopy (EDX), X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF SIMS). Optical and electron microscopy revealed heavily deformed Ti powder particles penetrating 10 to 30 μm into the Al substrate. Examination using TEM did not reveal any evidence of second phases at the interface suggesting a sharp transition between the two metals. The presence of nanocrystals and grain refinement of both the coating and the substrate suggest the formation of a partial hetero-epitaxy condition near the interface. EDX results from a dedicated high-resolution scanning transmission electron microscope showed a sharp compositional change with a maximum inter-diffusion region of about 5 nm. Bonding of the coating to the substrate is therefore thought to be achieved by the particle/substrate interlocking and direct metal to metal bonding. However, it is most likely that the refine crystalline structure near the interface will be beneficial to the adhesion of the coating. XPS and ToF SIMS provided evidence of nitrogen pick-up during the spray process in the form of N and TiN even when utilizing Helium as the gas carrier. The presence of TiN suggests reaction of the Ti with the entrained air during spraying which explains the occurrence of flashing jet outside the nozzle. Investigation of the material properties using nanoindentation showed reasonably consistent hardness and elastic modulus values throughout the titanium coating and at the transition region. The hardness was slightly higher than typical commercially available bulk Ti.     

Moderate concentration of citric acid for the formation of LaMn03 and LaCo03 nano-perovskites

Stoichiometric LaMnO3 and LaCoO3 nanoparticles were synthesized via calcination of a dried solution, containing molar ratio of La（NO3）3＋6H20/[Mn（NO3）2-4H20 or Co（NO3）2-6H20]=1 and citric acid as disperser at temperature range of 600-900 ℃for 5 h. The role of organic additive concentration, which was 0.0, 1.0, 2.5 and 5 times of the total number of moles of the nitrate ions, was investigated on phase formation, morphology, extent of crystallization and particle size of the products. Products were characterized by X-ray diffraction （XRD）, Fourier-transform infrared spectroscopy （FT-IR）, scanning electron microscopy （SEM） and Wansmission elec- tron microscopy （TEM） analysis. The tendency of lanthanum ion toward manganese cation was observed to be more than to cobalt cation for the formation of LaBO3 （B： Mn or Co） perovskite phase. A spongy product was formed on perovskite phase formation or in the pres- ence of citric acid. A constructive or destructive effect was observed for the organic disperser on perovskite phase formation, which de- pended on mole of the citric acid.     

Repression of MUC1 Promotes Expansion and Suppressive Function of Myeloid-Derived Suppressor Cells in Pancreatic and Breast Cancer Murine Models

Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells that are responsible for immunosuppression in tumor microenvironment. Here we report the impact of mucin 1 (MUC1), a transmembrane glycoprotein, on proliferation and functional activity of MDSCs. To determine the role of MUC1 in MDSC phenotype, we analyzed MDSCs derived from wild type (WT) and MUC1-knockout (MUC1KO) mice bearing syngeneic pancreatic (KCKO) or breast (C57MG) tumors. We observed enhanced tumor growth of pancreatic and breast tumors in the MUC1KO mice compared to the WT mice. Enhanced tumor growth in the MUC1KO mice was associated with increased numbers of suppressive MDSCs and T regulatory (Tregs) cells in the tumor microenvironment. Compared to the WT host, MUC1KO host showed higher levels of iNOS, ARG1, and TGF-β, thus promoting proliferation of MDSCs with an immature and immune suppressive phenotype. When co-cultured with effector T cells, MDSCs from MUC1KO mice led to higher repression of IL-2 and IFN-γ production by T cells as compared to MDSCs from WT mice. Lastly, MDSCs from MUC1KO mice showed higher levels of c-Myc and activated pSTAT3 as compared to MDSCs from WT mice, suggesting increased survival, proliferation, and prevention of maturation of MDSCs in the MUC1KO host. We report diminished T cell function in the KO versus WT mice. In summary, the data suggest that MUC1 may regulate signaling pathways that are critical to maintain the immunosuppressive properties of MDSCs.     

Polymerization initiation by N-p-tolylglycine: Free-radical reactions studied by pulse and steady-state radiolysis

The extensive use of N-p-tolylglycine (NTG) and analogous compounds in adhesive bonding technologies requires a better understanding of their role in initiating free-radical polymerization. The fast oxidation and reduction reactions of NTG proceed via the formation of various free radicals and radical cation and anion intermediates. These intermediates were identified and their reactivity with oxygen, to produce the corresponding peroxyl radicals, was measured. Hydroxyl radicals (?H) were used to initiate oxidation reactions of NTG, while the reduction reactions were initiated with hydrated electrons (e). OH radicals react with NTG predominately by addition to the aromatic ring followed by OHÞ elimination to produce NTG⁺· radical cations. In the presence of oxygen, the OH–NTG^? adduct also reacts with oxygen to produce peroxyl radicals. The reaction of NTG with e forms the radical anion, which subsequently protonates on the aromatic ring to produce cyclohexadienyl radicals, or undergoes an amine elimination to yield an acetic acid free radical and 4-methylaniline. Hydroperoxyl radicals (HO) abstract hydrogen from the α position of NTG to form the corresponding alkyl free radical. © 1994 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Quality Management in Pakistan's Readymade Garments' Industry

Pakistan's readymade garments' industry is a key player in Pakistan's industry in general, and its textile industrial output and exports in particular. In a liberalizing international trade regime, quality will be a critical success factor in the international competitiveness of Pakistan's readymade garments. Research in quality management in Pakistan's readymade garments' industry was undertaken. To gain further information, a postal self-completion questionnaire was mailed to 101 members of the Pakistan Readymade Garments' and Exporters' Association (PRGMEA). The response rate was 32%. It was found that while this industrial segment was in various stages of development, it needs to graduate fast to advanced quality management concepts of Kaizen and total quality management in order to maintain its competitive advantage in an environment that will soon be liberalized fully.     

Fabrication and Characterization of SiO2/(3-Aminopropyl)triethoxysilane-Coated Magnetite Nanoparticles for Lead(II) Removal from Aqueous Solution

A novel nano-adsorbent SiO₂/(3-aminopropyl)triethoxysilane-coated magnetite nanoparticles was synthesized for the adsorption of lead ions from water samples. Its structure and magnetic characteristics were characterized, by FTIR, powder X-ray diffraction, scanning electron microscope (SEM), transmission electron microscope (TEM) and vibrating sample magnetometry (VSM). Amino-functionalized SiO₂ coated Fe₃O₄ magnetite nano-adsorbent exhibited superparamagnetic behavior and strong magnetization at room temperature. The efficiency of the nano-adsorbent in separation of the metals was evaluated by adsorption technique. Kinetic data were analyzed using the pseudo-first-order and pseudo-second-order equations. The data fitted very well to the pseudo-second-order kinetic model.The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms and Langmuir model fitted well. The monolayer adsorption capacity was found as 17.65 mg/g at pH 4.0. Thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were also calculated. These parameters showed that the adsorption of Pb(II) onto nano-adsorbent was feasible, spontaneous and endothermic. The amino-functionalized SiO₂ coated Fe₃O₄ magnetic nano-adsorbent shows high adsorption capability for metal ions from aqueous solutions via the chelation mechanisms. The Pb(II) loaded nano-adsorbent can be easily recovered from aqueous solution with magnetic separation and regenerated readily by acid treatment. The product of this work can be used as an effective and recyclable nano-adsorbent for the removal of metal ions in wastewater treatment.