Study of accumulation behaviour of tungsten based composite using electron probe micro analyser for the application in bone tissue engineering

In this research, a proto-type study we have conducted, where we have synthesized tungsten based composite materials which are tungsten along with combined oxides of other elements like calcium, scandium, barium, and aluminium in the form of powder with bones powder of mice devised by high energy ball mill and later on fabricating high dense pellets by sintering by spark plasma. The particle sizes of the composite materials are found to be 1–2 µm, as evidenced by the electron microscope, suggesting synthesized materials are of micron size. The quantitative and qualitative analysis of sintered pellets are well confirmed by electron probe micro analyzer (EPMA) and energy dispersive X-ray spectrometer (EDS) which illustrate the greater percentage of tungsten presents in the profound scan areas with other elements of the composite. The absence of pores across the 3D geometry suggesting dense sample, which is quite revealed by the X-ray tomography inspection. The prepared sintered pellets from the tungsten based composites are found to be ≈ 99.5% density with the observation of tungsten to be accumulated uniformly across the scan regions along with focussed hot spots as implied by EPMA. This study paves the way, to examine how the tungsten accumulation and the distribution with the other elements for future understanding in bone tissue engineering application and the in vivo specification of tungsten.     

Computer modeling of substrate binding to lipases from Rhizomucor miehei, Humicola lanuginosa, and Candida rugosa.

The substrate-binding sites of the triacyl glyceride lipases from Rhizomucor miehei, Humicola lanuginosa, and Candida rugosa were studied by means of computer modeling methods. The space around the active site was mapped by different probes. These calculations suggested 2 separate regions within the binding site. One region showed high affinity for aliphatic groups, whereas the other region was hydrophilic. The aliphatic site should be a binding cavity for fatty acid chains. Water molecules are required for the hydrolysis of the acyl enzyme, but are probably not readily accessible in the hydrophobic interface, in which lipases are acting. Therefore, the hydrophilic site should be important for the hydrolytic activity of the enzyme. Lipases from R. miehei and H. lanuginosa are excellent catalysts for enantioselective resolutions of many secondary alcohols. We used molecular mechanics and dynamics calculations of enzyme-substrate transition-state complexes, which provided information about molecular interactions important for the enantioselectivities of these reactions.     

Combination of dual-energy computed tomography and iterative metal artefact reduction to increase general quality of imaging for radiotherapy patients with high dense materials. Phantom study

PurposeTo evaluate the use of pseudo-monoenergetic reconstructions (PMR) from dual-energy computed tomography, combined with the iterative metal artefact reduction (iMAR) method.MethodsPseudo-monoenergetic CT images were obtained using the dual-energy mode on the Siemens Somatom Definition AS scanner. A range of PMR combinations (70–130 keV) were used with and without iMAR. A Virtual Water™ phantom was used for quantitative assessment of error in the presence of high density materials: titanium, alloys 330 and 600. The absolute values of CT number differences (AD) and normalised standard deviations (NSD) were calculated for different phantom positions. Image quality was assessed using an anthropomorphic pelvic phantom with an embedded hip prosthesis. Image quality was scored blindly by five observers.ResultsAD and NSD values revealed differences in CT number errors between tested sets. AD and NSD were reduced in the vicinity of metal for images with iMAR (p < 0.001 for AD/NSD). For ROIs away from metal, with and without iMAR, 70 keV PMR and pCT AD values were lower than for the other reconstructions (p = 0.039). Similarly, iMAR NSD values measured away from metal were lower for 130 keV and 70 keV PMR (p = 0.002). Image quality scores were higher for 70 keV and 130 keV PMR with iMAR (p = 0.034).ConclusionThe use of 70 keV PMR with iMAR allows for significant metal artefact reduction and low CT number errors observed in the vicinity of dense materials. It is therefore an attractive alternative to high keV imaging when imaging patients with metallic implants, especially in the context of radiotherapy planning.     

Evaluating regional water security through a freshwater ecosystem service flow model: A case study in Beijing-Tianjian-Hebei region,China

Freshwater ecosystem service is essential to human’s survival and development. Many studies have documented the spatial differences in the supply and demand of ecosystem services and proposed the concept of ecosystem services flows. However, few studies characterize freshwater ecosystem service flow quantitatively. Therefore, our paper aims to quantify the effects of freshwater ecosystem service flow on downstream areas. We developed a freshwater ecosystem service flow model and applied it in the Beijing–Tianjin–Hebei (BTH) region, China, for the year of 2000, 2005, and 2010. We assessed the regional water security with an improved freshwater security index by integrating freshwater service provision, consumption and flow; and found that most areas of the BTH region (69.2%) were affected by upstream freshwater flows. The areas achieving water security in the region also expanded to 66.9%, 66.1%, and 71.3%, which were 6.4%, 6.8% and 5.7% increments compared to no-flow situation, in 2000, 2005 and 2010, respectively. Setting quota for human water consumption is suggested to further improve water security. These results highlight the need to fully understand the connections between distant freshwater ecosystem service provision and local freshwater ecosystem service consumption. This approach may also help managers to choose more sustainable strategies for critical freshwater resource management across different regions.     

Rechargeable Dual‐Ion Batteries with Graphite as a Cathode: Key Challenges and Opportunities

Rechargeable graphite dual‐ion batteries (GDIBs) have attracted the attention of electrochemists and material scientists in recent years due to their low cost and high‐performance metrics, such as high power density (≈3–175 kW kg^?1), energy efficiency (≈80–90%), long cycling life, and high energy density (up to 200 Wh kg^?1), suited for grid‐level stationary storage of electricity. The key feature of GDIBs is the exploitation of the reversible oxidation of the graphite network with concomitant and highly efficient intercalation/deintercalation of bulky anionic species between graphene layers. In this review, historical and current research aspects of GDIBs are discussed, along with key challenges in their development and practical deployment. Specific emphasis is given to the operational mechanism of GDIBs and to unbiased and correct reporting of theoretical cell‐level energy densities.     

Encapsulating Trogtalite CoSe2 Nanobuds into BCN Nanotubes as High Storage Capacity Sodium Ion Battery Anodes

Trogtalite CoSe₂ nanobuds encapsulated into boron and nitrogen codoped graphene (BCN) nanotubes (CoSe₂@BCN‐750) are synthesized via a concurrent thermal decomposition and selenization processes. The CoSe₂@BCN‐750 nanotubes deliver an excellent storage capacity of 580 mA h g^?1 at current density of 100 mA g^?1 at 100th cycle, as the anode of a sodium ion battery. The CoSe₂@BCN‐750 nanotubes exhibit a significant rate capability (100–2000 mA g^?1 current density) and high stability (almost 98% storage retention after 4000 cycles at large current density of 8000 mA g^?1). The reasons for these excellent storage properties are illuminated by theoretical calculations of the relevant models, and various possible Na⁺ ion storage sites are identified through first‐principles calculations. These results demonstrate that the insertion of heteroatoms, B–C, N–C as well as CoSe₂, into BCN tubes, enables the observed excellent adsorption energy of Na⁺ ions in high energy storage devices, which supports the experimental results.     

Energy Metabolism in Rhizomes of Acorus calamus (L.) and in Tubers of Solanum tuberosum (L.) With Regard to their Anoxia Tolerance

Rhizomes of the marsh plant Acorus calamus (L.) and tubers of the flooding-intolerant Solanum tuberosum (L.) var. Bintje, both kept under strict anoxia, differ markedly in their fermentation properties. The fermentation capacities as measured by ADH and LDH activities and their respective product concentrations were estimated. While rhizomes of Acorus calamus, having high ADH and low LDH activities, accumulate mainly ethanol, tubers of Solanum tuberosum tend towards lactic acid fermentation. The total amount of adenine nucleotides is quite stable in Acorus calamus, whereas they show a sharp decline in S. tuberosum during the first 6h of anoxia. The adenylate energy charge of A. calamus recovers after a short initial drop (AEC > 0.8). AEC values of S. tuberosum decrease rapidly and remain at very low values (AEC ～ 0.3). Tuber tissues became soft and lost viability after about 48–72 h of anoxia at 25 °C. This might be due to tissue acidification and impaired energy metabolism, but not to the lack of energy reserves. Energy metabolism of A. calamus is well adapted to anoxia.     

The effect of exercise intensity and duration on the oxygen deficit and excess post-exercise oxygen consumption

Nine males with mean maximal oxygen consumption (VO2max) = 63.0 ml.kg-1.min-1, SD 5.7 and mean body fat = 10.6%, SD 3.1 each completed nine counterbalanced treatments comprising 20, 50 and 80 min of treadmill exercise at 30, 50 and 70% VO2max. The O2 deficit, 8 h excess post-exercise oxygen consumption (EPOC) and EPOC:O2 deficit ratio were calculated for all subjects relative to mean values obtained from 2 control days each lasting 9.3 h. The O2 deficit, which was essentially independent of exercise duration, increased significantly (P less than 0.05) with intensity such that the overall mean values for the three 30%, 50% and 70% VO2max workloads were 0.83, 1.89 and 3.09 l, respectively. While there were no significant differences (P greater than 0.05) between the three EPOCs after walking at 30% VO2max for 20 (1.01 l), 50 (1.43 l) and 80 min (1.04 l), respectively, the EPOC thereafter increased (P less than 0.05) with both intensity and duration such that the increments were much greater for the three 70% VO2max workloads (EPOC: 20 min = 5.68 l; 50 min = 10.04 l; 80 min = 14.59 l) than for the three 50% VO2max workloads (EPOC: 20 min = 3.14 l; 50 min = 5.19 l; 80 min = 6.10 l). An analysis of variance indicated that exercise intensity was the major determinant of the EPOC since it explained five times more of the EPOC variance than either exercise duration or the intensity times duration interaction. The mean EPOC:O2 deficit ratio ranged from 0.8 to 4.5 and generally increased with both exercise intensity and duration.(ABSTRACT TRUNCATED AT 250 WORDS)