Results 1 - 10 of 1231
Results 1 - 10 of 1231. Search took: 0.031 seconds
|Sort by: date | relevance|
[en] A theoretical method for investigating the inter-relation between the electronic and molecular structures of 3d configuration ions in a tetragonal ligand field is established on the basis of the 120 × 120 complete energy matrices. Using this method, the local structure parameters of two tetragonal Cr3+ centers in the NH4Cl:Cr3+ system are determined. Furthermore, the relations between the molecular symmetry and the ligand field symmetry are discussed. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
[en] Molecule-targeted therapy has become the research focus for hepatocellular carcinoma (HCC). Persistent PI3K-AKT activation is often detected in HCC, representing a valuable oncotarget for treatment. Here, we tested the anti-HCC activity by a potent AKT inhibitor: AKT inhibitor 1/2 (AKTi-1/2). In both established (HepG2 and Huh-7) and primary human HCC cells, treatment with AKTi-1/2 inhibited cell survival and proliferation, but induced cell apoptosis. AKTi-1/2 blocked AKT-mTOR activation, yet simultaneously provoked cytoprotective autophagy in HCC cells. The latter was evidenced by ATG-5 and Beclin-1 upregulation, p62 downregulation as well as LC3B-GFP puncta formation. Autophagy inhibition, via pharmacological inhibitors (3-methyladenine, ammonium chloride, and bafilomycin A1) or Beclin-1 siRNA knockdown, significantly potentiated AKTi-1/2-induced HepG2 cell death and apoptosis. In nude mice, AKTi-1/2 intraperitoneal injection inhibited HepG2 tumor growth. Significantly, its anti-tumor activity in vivo was further sensitized when combined with Beclin-1 shRNA knockdown in HepG2 tumors. Together, these results demonstrate that autophagy activation serves as a main resistance factor of AKTi-1/2 in HCC cells. Autophagy prevention therefore sensitizes AKTi-1/2-induced anti-HCC activity in vitro and in vivo. - Highlights: • AKTi-1/2 inhibits human HCC cells in vitro. • Autophagy inhibitors sensitize AKTi-1/2-induced HCC cell death and apoptosis. • Beclin-1 siRNA potentiates AKTi-1/2-induced HepG2 cell death and apoptosis. • Beclin-1 knockdown augments AKTi-1/2-induced anti-HepG2 tumor activity in vivo.
[en] Determination conditions of uranium mixture such as dissolve method of uranium, determination method and interference of matrix were studied. Interference on the determination of uranium was eliminated by coordinating matrix elements in solution with NH4F. The quantitative analysis method of uranium in uranium mixture was built by precision experiments. Relative standard uncertainty of this method was below 0.2% by determination of simulation samples. (authors)
[en] Ammonium chloride is a destructive agent of localized corrosion which poses devastating threat to refining structure integrity and the safety of the refinery processes. Ammonium chloride is an underdeposit corrosion commonly found in overhead equipment and piping for crude and hydroprocessing units. This form of insidious form of corrosion had caused severe fouling that posed negative impact on the operating reliability of various processing units. This review addresses the corrosion mechanism of ammonium chloride, affected materials and equipment, Environmental factors for its impact, thermodynamic behavior of a wet ammonium chloride system, some case studies of ammonium chloride and the preventive measures to mitigate its effect. (paper)
[en] Patterned silver nanoparticle (NP)-poly[2-(methacryloyloxy)ethyl] trimethyl ammonium chloride (AgNP-polyMETAC) composites were prepared by electrochemical lithography, surface-initiated atom-transfer radical polymerization (SI-ATRP) and NP growth inside the polymer brushes. For this purpose, polymer brushes of poly[2-(methacryloyloxy)ethyl] trimethyl ammonium chloride (polyMETAC) were utilized as strong electrolyte brush system. These were introduced in form of patterned polymer brushes to create pH-responsive surface enhanced Raman scattering SERS substrates. It is well-known that the charges of strong polyelectrolyte chains are usually insensitive to pH changes, hence, rarely strong polyelectrolyte brushes have been utilized so far to study pH-responsive properties of such films. Here pH-insensitive polyMETAC brushes exhibit pH-sensitive properties and can be used as pH-responsive surfaces for SERS applications due to the embedding of AgNPs into the polymer brushes. When increasing the pH, the assembly of the AgNPs transfers from quasi two-dimensional (2D) aggregates, attaching mainly to the polymer surface, into a three-dimensional (3D) assembly, where the particles are penetrating into the brushes. These changes result in significant alterations of the SERS efficiency of the polymer brush composite. At pH 5, the enhancement of the Raman scattering approaches its maximum. The fabricated SERS substrates show a high sensitivity as well as good experimental reliability at different pH values. Moreover, electrochemical lithography was utilized to fabricate patterned SERS substrate, which allows an easy combination of multiple other functionalities in hierarchical structuring steps. In addition, the microstructure is in our studies beneficial because of a simplified and reliable characterization of the polymer brushes at defined sample areas. The introduction of the microstructured brush system is regarded moreover attractive for the development of high-throughput platforms for rapid, automated screening and analysis applications. (paper)
[en] In this paper, superhydrophobic and antibacterial fabric is fabricated via the sequential deposition of polydopamine (PDA), quaternized nanosilica particles and hexadecyltrimethoxy silane (HDTMS). The epoxypropyl dodecyl dimethyl ammonium chloride (EPDDAC)-modified silica particles simultaneously contributed to the antibacterial activity and generated a rough surface on the textiles. According to the results, the obtained fabric showed excellent superhydrophobicity, good washability, and high antibacterial activity against Escherichia coli and Staphylococcus aureus.
[en] Highlights: • SNX7 has been proposed to be linked with Alzheimer's disease. • Overexpression of SNX7 reduces the production of Aβ and sAPPβ. • It also reduces the cellular level of APP. • The reduction of APP is reversed by inhibitors of lysosomal degradation. • Our results suggest that SNX7 takes part in directing APP for degradation. Abnormal production of amyloid-β peptides (Aβ) by proteolytic processing of amyloid precursor protein (APP) is thought to be central to the pathogenesis of Alzheimer's disease (AD). Although many efforts have been made to investigate mechanisms that regulate APP processing, many details remain incompletely understood. Sorting nexins (SNXs) are a family of proteins which are involved in many intracellular trafficking events. Several SNXs have been implicated in APP processing and Aβ production. In this study, we extended the investigation to SNX7. We found that overexpression of SNX7 in HEK293T cells reduces the levels of secreted Aβ and β-cleaved N-terminal APP fragments (sAPPβ). Moreover, SNX7 overexpression caused a significant reduction of the steady-state levels of APP as well as of the cell surface APP levels. By using NH4Cl and Bafilomycin A1 to inhibit the lysosomal degradative pathway, we found that the reduction of APP induced by SNX7 overexpression was prevented by such inhibition. No change in the cell surface distribution or steady-state levels of BACE1 was detected after overexpression of SNX7. Taken together, these results suggest that SNX7 regulates Aβ production by directing APP for degradation.
[en] Fluorination of metal oxide using NH4HF2 is one of the most convenient methods of preparing pure metal fluoride. In this paper, some interesting results are evident when NH4HF2 is reacted with various metal oxides and subsequently reducing the pure metal flourides to yield high pure metals. It may be noted that pure metal fluorides, even though expensive, are excellent starting intermediates for making pure metals. The fluorination of these metal oxides interestingly begins right at room temperature. Room temperature thermal analysis and phase evolution with time corroborates to the above fact. At room temperature, it can be seen that not only one but several reactions occurred in steps yielding to different ammonium metallo-fluorides. NH4F or NH3 is formed as the by-product of the reaction depending on the initial fluoride content of charge. Further thermal studies of room temperature reacted samples show that these ammonium metallo-fluorides, decomposes further leading to several other intermediates finally yielding pure metal fluoride. It can also be seen that substantial evaporation of NH4HF2 is possible even before it is able to participate in the reaction. This may result in disturbing the stoichiometry of the initial charge allowing unreacted oxides to remain, which gets converted to metal oxyfluorides (MxOyFz) by reacting with pure fluoride and can cause oxygen to remain in the final product as an oxyfluoride. Additionally, in certain metal oxides, there is a tendency of formation of ammonium metallo-oxy fluorides, which on decomposing can transform back to oxide, instead of a fluoride. Such interesting variations and different process modifications on how to make pure oxygen free metal fluorides will be discussed in the paper. Reduction of this pure fluorides to metal will also be discussed. Variation of “spot technique” commonly used for liquidus determination was used to determine the high temperature reduction steps. Determining the precise process steps helped in enhancing the overall yield and efficiency of the process. (author)