Graphene and derivatives – Synthesis techniques, properties and their energy applications

2D nanomaterials with exceptional electrical, mechanical and thermal properties are promising reinforcing materials for fabricating high-performance composite materials. Rapid developments in nanotechnology in recent years have facilitated the development of advanced materials for functional devices. In particular, this review is focussed on the application of graphene nanoparticle-based composites (GNP's) and graphene derivatives in the fields of energy storage and conversion devices. This review focuses on these recent developments including the synthesis of graphene-based materials and its derivative, as well as the related achieved electrical, mechanical and thermal properties

Parametric study for graphene reinforced aluminum matrix composites production using Box Behnken design

The production of graphene reinforced aluminum matrix composite through powder metallurgical route requires optimization of process parameters to obtain better performance characteristics. One of the advanced method available for statistical analysis of parameters is Response Surface Methodology (RSM). The statistical analysis was carried out with three parameters, weight percentage of graphene reinforcement Wg (0.05%, 0.1% and 0.2%), stirring time ST(1h, 2h and 3h) and compaction pressure Pc(16T, 17T and 19T) while sintering temperature T kept constant. The performance of the Box Behnken design was analyzed and optimized using Design Expert software for the effective production of composites. From the results obtained from the analysis, the best set of parameters were considered for the future production of composites

Topoisomerase IB: a relaxing enzyme for stressed DNA

DNA topoisomerase I enzymes relieve the torsional strain in DNA; they are essential for fundamental molecular processes such as DNA replication, transcription, recombination, and chromosome condensation; and act by cleaving and then religating DNA strands. Over the past few decades, scientists have focused on the DNA topoisomerases biological functions and established a unique role of Type I DNA topoisomerases in regulating gene expression and DNA chromosome condensation. Moreover, the human enzyme is being investigated as a target for cancer chemotherapy. The active site tyrosine is responsible for initiating two transesterification reactions to cleave and then religate the DNA backbone, allowing the release of superhelical tension. The different steps of the catalytic mechanism are affected by various inhibitors; some of them prevent the interaction between the enzyme and the DNA while others act as poisons, leading to TopI-D NA lesions, breakage of DNA, and eventually cellular death. In this review, our goal is to provide an overview of mechanism of human topoisomerase IB action together with the different types of inhibitors and their effect on the enzyme functionality

Mechanical properties of graphene oxide reinforced aluminium matrix composites

In this paper, the properties of powder metallurgy produced samples of GO reinforced aluminium composites were examined. Discs of 20 mm diameter and 0.5 mm thickness were made from pure Al powder of 35 μm particle size and with GO reinforcement at different GO wt% (0.05, 0.1 and 0.2). The mixture of Al/GO powders prepared through liquid infiltration were cold compacted and then sintered. The GO reinforced Al matrix composites were characterised using the scanning e lectron microscope with energy dispersion spectroscopy (SEM/ EDX ) for investigation of the homogeneous dispersion of GO into the matrix. X - ray diffraction (XRD) analysis for crystallographic phase and micro - Raman spectroscopy w as used to identify the phases inside the composite matrix after the sintering process. Micro hardness and the strength values from the produced Al/GO composites were recorded. It is evident from the results obtained that where uniform mixing is achieved, GO reinforced Al composites ca n be produced with similar hardness values as for those produced from rGO reinforced Al composites

In vitro and in silico characterization of an antimalarial compound with antitumor activity targeting human DNA topoisomerase IB

Human DNA topoisomerase IB controls the topological state of supercoiled DNA through a complex catalytic cycle that consists of cleavage and religation reactions, allowing the progression of fundamental DNA metabolism. The catalytic steps of human DNA topoisomerase IB were analyzed in the presence of a drug, obtained by the open-access drug bank Medicines for Malaria Venture. The experiments indicate that the compound strongly and irreversibly inhibits the cleavage step of the enzyme reaction and reduces the cell viability of three different cancer cell lines. Molecular docking and molecular dynamics simulations suggest that the drug binds to the human DNA topoisomerase IB-DNA complex sitting inside the catalytic site of the enzyme, providing a molecular explanation for the cleavage-inhibition effect. For all these reasons, the aforementioned drug could be a possible lead compound for the development of an efficient anti-tumor molecule targeting human DNA topoisomerase IB

Is routine hepaticojejunostomy at the time of unplanned surgical bypass required in the era of self-expanding metal stents?

Background: Hepaticojejunostomy is routinely performed in patients when inoperable disease is found at planned pancreatoduodenectomy; however, in the presence of self-expanding metal stent (SEMS) hepaticojejunostomy may not be required. The aim of this study was to assess biliary complications and outcomes in patients with unresectable disease at time of planned pancreaticoduodenectomy stratified by the management of the biliary tract.Material and methods: Retrospective analysis of patients undergoing surgery in January 2010-December 2015. Complications were measured using the Clavien-Dindo scale.Results: Of 149 patients, 111 (75%) received gastrojejunostomy and hepaticojejunostomy (double bypass group) and 38 (26%) received a single bypass in the presence of SEMS (single bypass group). Post-operative non-biliary [7 (18%) vs 43 (38%), (p = 0.028)] and biliary [0% vs 12 (11%), (p = 0.037)] complications were lower in the single bypass group. Hospital readmissions were significantly higher in the double bypass group (p = 0.021). Overall survival and the time to start chemotherapy were equivalent (p = n.s.).Conclusions: Complications are more common following double bypass compared to single bypass with SEMS suggesting that gastric bypass is adequate surgical palliation in presence of SEMS. This study adds further evidence that preoperative SEMS should be used in preference to plastic stents for suspected periampullary malignancy

Pancreas exocrine replacement therapy is associated with increased survival following pancreatoduodenectomy for periampullary malignancy

Background: Although many patients undergoing pancreatoduodenectomy (PD) for cancer have pancreatic exocrine insufficiency, pancreatic enzyme replacement therapy (PERT) is not routinely used, and effects upon post-operative survival are unclear.Methods: This review of patients undergoing PD for periampullary malignancy sought to test for an association between PERT and overall survival, with post-hoc subgroup analysis performed after stratifying patients by the year of surgery, pancreatic duct width and tumour type.Results: Some 202/469 (43.1%) patients received PERT. After accounting for pathological variables and chemotherapy, PERT use was found to be independently associated with improved survival on multivariable analysis [HR 0.72 (95% CI: 0.52-0.99), p = 0.044] and on propensity matched analysis (p = 0.009). The effect of PERT upon improved survival was predominantly observed amongst patients with a dilated pancreatic duct (>= 3 mm).Discussion: PERT use was independently associated with improved survival following PD for cancer. The validity of this observation is supported by an effect largely confined to those patients with a dilated pancreatic duct. The nutritional status of patients undergoing PD for cancer needs further investigation and the effects of PERT require verification in further clinical studies