PRKAR1B-AS2 Long Noncoding RNA Promotes Tumorigenesis,Survival, and Chemoresistance via the PI3K/AKT/mTOR Pathway

Many long noncoding RNAs have been implicated in tumorigenesis and chemoresistance; however, the underlying mechanisms are not well understood. We investigated the role of PRKAR1B-AS2 long noncoding RNA in ovarian cancer (OC) and chemoresistance and identified potential downstream molecular circuitry underlying its action. Analysis of The Cancer Genome Atlas OC dataset, in vitro experiments, proteomic analysis, and a xenograft OC mouse model were implemented. Our findings indicated that overexpression of PRKAR1B-AS2 is negatively correlated with overall survival in OC patients. Furthermore, PRKAR1B-AS2 knockdown-attenuated proliferation, migration, and invasion of OC cells and ameliorated cisplatin and alpelisib resistance in vitro. In proteomic analysis, silencing PRKAR1B-AS2 markedly inhibited protein expression of PI3K-110α and abrogated the phosphorylation of PDK1, AKT, and mTOR, with no significant effect on PTEN. The RNA immunoprecipitation detected a physical interaction between PRKAR1B-AS2 and PI3K-110α. Moreover, PRKAR1B-AS2 knockdown by systemic administration of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine nanoparticles loaded with PRKAR1B-AS2–specific small interfering RNA enhanced cisplatin sensitivity in a xenograft OC mouse model. In conclusion, PRKAR1B-AS2 promotes tumor growth and confers chemoresistance by modulating the PI3K/AKT/mTOR pathway. Thus, targeting PRKAR1B-AS2 may represent a novel therapeutic approach for the treatment of OC patients.     

New Schiff Base Cationic Surfactants: Surface and Thermodynamic Properties and Applicability in Bacterial Growth and Metal Corrosion Prevention

A new series of cationic Schiff bases was synthesized and their chemical structures were confirmed using elemental analysis, infrared spectra and nuclear magnetic resonance. The surface properties of the surfactant solutions including surface tension, effectiveness, efficiency, critical micelle concentration, maximum surface excess and minimum surface area were calculated using surface tension-log concentration profiles. The surface parameters were strongly dependent on the hydrophobic chain length. The thermodynamic properties of the surfactants in their solutions showed the spontaneous behavior of both adsorption and micellization processes. The thermodynamic data revealed that the adsorption of the surfactant molecules at the air/water interface was more favorable than the micellization in the bulk of their solutions. The synthesized surfactants were evaluated with regard to their preventing the corrosion reaction of carbon steel in acidic media and also their acting as antibacterial biocides to inhibit bacterial growth. The data of corrosion and antibacterial evaluations showed the high efficiency and applicability of these compounds in these uses.     

Efficient hydrogen storage in defective graphene and its mechanical stability: A combined density functional theory and molecular dynamics simulation study

A combined density functional theory and molecular dynamics approach is employed to study modifications of graphene at atomistic level for better H₂ storage. The study reveals H₂ desorption from hydrogenated defective graphene structure, V₂₂₂, to be exothermic. H₂ adsorption and desorption processes are found to be more reversible for V₂₂₂ as compared to pristine graphene. Our study shows that V₂₂₂ undergoes brittle fracture under tensile loading similar to the case of pristine graphene. The tensile strength of V₂₂₂ shows slight reduction with respect to their pristine counterpart, which is attributed to the transition of sp² to sp³-like hybridization. The study also shows that the V₂₂₂ structure is mechanically more stable than the defective graphene structure without chemically adsorbed hydrogen atoms. The current fundamental study, thus, reveals the efficient recovery mechanism of adsorbed hydrogen from V₂₂₂ and paves the way for the engineering of structural defects in graphene for H₂ storage.     

Thermo-mechanical finite element model of friction stir welding of dissimilar alloys

A thermo-mechanical finite element model is developed based on Coupled Eulerian Lagrangian method to simulate the friction stir welding of dissimilar Al6061-T6 and Al5083-O aluminum alloys using different tool pin profiles. The model is validated using published measured temperatures and weld microstructure. The finite element results show that maximum temperatures at the weld joint were below the materials’ melting point. Placing the harder alloy (Al6061-T6) at advancing side led to a decrease in maximum process temperature and strain rate, but increased tool reaction loads. Featured tool pin produced better material mixing resulting in enhanced joint quality with reduced volumetric defects.     

Latency hiding on COMA multiprocessors

Cache-only memory access (COMA) multiprocessors support scalable coherent shared memory with a uniform memory access programming model. The local portion of shared memory associated with a processor is organized as a cache. This cache-based organization of memory results in long remote memory access latencies. Latency-hiding mechanisms can reduce effective remote memory access latency by making data present in a processor's local memory by the time the data are needed. In this paper we study the effectiveness of latency-hiding mechanisms on the KSR2 multiprocessor in improving the performance of three programs. The communication patterns of each program are analyzed and the mechanisms for latency hiding are applied. Results from a 52-processor system indicate that these mechanisms hide a significant portion of the latency of remote memory accesses. The results also quantify benefits in overall application performance.An earlier version of this paper was presented at the 1995 International Conference on Parallel Processing Techniques and Applications.     

Along-wind gust effect on elevated structures

The interest in the evaluation of the dynamic response of elevated structures to wind force has increased considerably in recent years. This paper introduces a random process approach and its application to these special structures. As an example, a skylight structure is analysed by random approach in regard to the gust effect. For comparison, the same effects are also evaluated by using some of the current available building codes.Results show that the effect due to the gust is greater than that due to the steady wind. Wind pressure obtained through the random approach are quite comparable with those obtained by using the building codes. However, the random approach presented in this paper provides more detailed procedure than the building code approach for evaluating gust effect on elevuated structures.     

Numerical investigation & comparison of a tandem-bladed turbocharger centrifugal compressor stage with conventional design

Extensive numerical investigations of the performance and flow structure in an unshrouded tandem-bladed centrifugal compressor are presented in comparison to a conventional compressor. Stage characteristics are explored for various tip clearance levels, axial spacings and circumferential clockings. Conventional impeller was modified to tandem-bladed design with no modifications in backsweep angle, meridional gas passage and camber distributions in order to have a true comparison with conventional design. Performance degradation is observed for both the conventional and tandem designs with increase in tip clearance. Linear-equation models for correlating stage characteristics with tip clearance are proposed. Comparing two designs, it is clearly evident that the conventional design shows better performance at moderate flow rates. However; near choke flow, tandem design gives better results primarily because of the increase in throat area. Surge point flow rate also seems to drop for tandem compressor resulting in increased range of operation.     

Co-solvent ethanolysis of chicken waste: Optimization of parameters and characterization of biodiesel

Fatty acid ethyl ester (FAEE) was developed from chicken waste. A blend of chicken fat and waste chicken oil was used as a feedstock for FAEE preparation via alkali-catalyzed transesterification with ethanol assisted by a co-solvent. Hexane was used as the co-solvent. The influences of alkali catalyst type and concentration, ethanol/blend molar ratio, hexane/ethanol volume ratio, temperature, time, and type of co-solvent on the yield of FAEE were investigated. The best yield of FAEE (96.94%~96.78% w/w ester content) was obtained at 0.75% KOH w/w, 8:1 ethanol/blend molar ratio, 1.5:1 hexane/ethanol volume ratio, 60°C temperature, and 60 min of reaction. The fuel properties of FAEE produced as well as its blends with petro diesel were within the range of those prescribed by ASTM D 6751 standards, indicating its suitability as fuel for combustion engines. It was concluded that the presence of co-solvent increased the yield of FAEE and enhanced its properties compared to FAEE produced via non-solvent processes. The process was found to follow first-order kinetics, and the activation energy was found to be 13.31 kJ/mol.