Human–seat interface analysis of upper and lower body weight distribution

The human–seat interfaces were analyzed to determine the differential distribution of the body weight to the components of seat. Fifteen volunteers were tested on a simulated seat system with two piezoelectric force platforms, one placed as chair seat pan and the other placed on the floor surface as footrest. The seated configurations included back inclines (75° and 80°), upright (90°) and reclines (95°, 105° and 115°), absence or presence of armrest (adjusted at 62–68 cm of height), forward and backward sloping of the seat pan, and supported and unsupported back. The armrest and backrest assemblies were isolated from the force platforms. The difference in the body weight (kgf) to the sum of forces recorded at seat pan and feet yielded the extent of weight transferred to other features (e.g., backrest and armrest). The weight distributed at seat was 10–12% less at back inclines (p<0.01) as compared to upright unsupported sitting. With the backrest reclined beyond 95°, the weight at seat gradually decreased by 9% at 115° recline. The load distributed at feet varied narrowly; however, it was significantly greater (p<0.01) at upright supported back, compared to unsupported back. The height of the armrest was optimized at 68 cm, since the weight distribution at seat pan consistently reduced by 12% at that height, as compared to the absence of armrest (F_(4,524)=8.80, p<0.05). The suggested height of the armrest corresponded to 40% of the body stature of the selected volunteers. The load distributed at feet was 18% greater with the presence of armrest, indicating that a part of the weight of the upper leg fell on the seat pan, when the armrest was absent. The weight fell on the seat in slouch posture was 5% less than in upright sitting, while the weight at feet was marginally higher in slouch than in upright posture. The study maintained that the horizontal as well as 5° forward slope of the seat might be the preferred choice, since the load distributed at seat was highest at backward sloping seat for all conditions of supported and unsupported back. The study reaffirms that the backrest and armrest have conjoint influence in reducing the load distributed at seat, which in turn might help in mitigating stress on the spinal and other paraspinal structures.

Relevance to Industry

The human–seat interface analysis and understanding of body weight distribution to the components of seat may be beneficial for ergo-design application in optimizing parameters for chair configurations that provide comfort and safety to the user.     

Coarsening kinetics of γ′ precipitates in cobalt-base alloys

The expeditious development of novel cobalt-base γ–γ′ alloys as possible next generation superalloys critically depends on achieving a comprehensive understanding of the coarsening kinetics of ordered γ′ precipitates. This paper discusses the coarsening of L1₂ ordered Co₃(W, Al) precipitates in a model ternary Co–10Al–10W (at.%) alloy during isothermal annealing at 800 and 900 °C. The experimentally determined temporal evolution of average size of the γ′ precipitates suggests classical matrix diffusion limited Lifshitz–Slyozov–Wagner coarsening at both temperatures. The γ′ coarsening rate constants have been determined using a modified coarsening rate equation for non-dilute solutions. Furthermore, using the Cahn–Hilliard formulation for interfacial energy, the γ/γ′ interfacial energies at the respective annealing temperatures have been correlated to the concentration profile across the interface that has been experimentally determined using atom probe tomography. The calculated interfacial energies are in comparable range with those observed in nickel-base superalloys. Additionally, this analysis has permitted, for the first time, the determination of the gradient energy coefficient for γ/γ′ interfaces in Co-base alloys, a critical input for phase-field and other simulation models for microstructural evolution.     

Identification and screening of antimalarial phytochemical reservoir from northeastern Indian plants to develop PfRIO-2 kinase inhibitor

Every year, malaria caused by Plasmodium falciparum leads to 1 million deaths. Disease condition is alarming due to acquired resistance in parasite against antimalarial drugs in circulation. It brings the necessity to design novel inhibitors against newly identified drug targets. RIO-2 kinase regulates ribosome biogenesis and represents a promising drug target. Northeastern region of India is a biodiversity hub with a rich source of medicinal plants. Medicinal plants represent a source of phytochemical library to be screened to develop an inhibitor against the PfRIO-2 kinase. In current report, we selected plants with known antimalarial activity and performed in silico screening with phytochemicals against PfRIO-2 as a target. The majority of antimalarial phytochemicals docked very well into the ATP binding pocket of the PfRIO-2 kinase. A competition assay with substrate ATP indicates that a total of 5 phytochemicals, rutin, bebeerines, isochondrodendrine, nimbin and punicalagin, share similar interactions with protein residues within the ATP binding pocket and have potential to inhibit ATP binding. A significant relationship was found between docking energy and experimentally determined antimalarial values of rutin, bebeerines, isochondrodendrine, nimbin and punicalagin (R ² = 0.91, p < 0.001). Docking and virtual screening has identified lead phytochemicals, namely rutin, bebeerines, isochondrodendrine, nimbin and punicalagin, as a potent PfRIO-2 inhibitor, but cannot replace experimental verification. We are hopeful that the current study will help to understand the antimalarial action of the phytochemicals and design effective chemotherapy against malaria.     

Influence of cobalt doping on the crystalline structure, optical and mechanical properties of ZnO thin films

Uniform and transparent thin films of Zn_1 − xCo_xO (0 ≤ x ≤ 0.10) were fabricated by sol-gel spin coating technique. Co addition up to x = 0.075, led to refinement in structure and improvement in film quality together with average grain size reduction from 17 nm in undoped ZnO to 15 nm with x = 0.05 and 12 nm with x = 0.10 Co additions. For x ≥ 0.035, CoO (cubic) was detected as the secondary phase. Influence of Co addition on the volume fraction of grain boundaries has been interpreted. Increase in Co content in the range 0 ≤ x ≤ 0.10 led to quenching of near-band edge and blue emissions, decrease in band gap energy (E_g) from 3.36 eV to 3.26 eV, decrease in film thickness and refractive index and an increase in extinction coefficient of Zn_1 − xCo_xO thin films. The change in nature of stress from compressive to tensile with lower to higher doping of Co is corroborative with the angular peak shift of (002) plane of ZnO lattice. An overall increase in microhardness of Zn_1 − xCo_xO thin films up to x = 0.05 is attributed to change in microstructure and evolution of secondary phase and as the secondary phase separates out the overall stress is released leading to lowering of hardness after this concentration. Hall-Petch behavior is also studied and found to obey until x = 0.05, however, considerable deviation after this dopant concentration is attributed to the increase in the volume fraction of grain boundaries, which results from the secondary phase separation from this dopant concentration.     

Recent trends on the development of photobiological processes and photobioreactors for the improvement of hydrogen production

Hydrogen production through biological routes is promising because they are environmentally friendly. Hydrogen production through biophotolysis or photofermentation is usually a two stage process. In the first stage CO₂ is utilized for biomass production which is followed by hydrogen production in the second stage in anaerobic/sulfur-deprived conditions. In addition, one-stage photobiological hydrogen production process can be achieved using selected cyanobacterial strains. The major challenges confronting the large scale production of biomass/hydrogen are limited not only on the performance of the photobioreactors in which light penetration in dense cultures is a major bottleneck but also on the characteristics of the organisms. Other dependable factors include area/volume (A/V) ratio, mode of agitation, temperature and gas exchange. Photobioreactors of different geometries are reported for biohydrogen production: Tubular, Flat plate, Fermentor type etc. Every reactor has its own advantages and disadvantages. Airlift, helical tubular and flat plate reactors are found most suitable with respect to biomass production. These bioreactors may be employed for hydrogen production with necessary modifications to overcome the existing bottlenecks like gas hold up, oxygen toxicity and poor agitation. This review article attempts to focus on existing photobioreactors with respect to biomass generation and hydrogen production and the steps taken to improve its performance through engineering innovation that definitely help in the future design and construction of photobioreactors.     

The Influence of Precipitation of Alpha2 on Properties and Microstructure in TIMETAL 6-4

Samples of Hot Isostatically Pressed (HIPped) powder of TIMETAL 6-4 (Ti-6Al-4V, compositions in wt pct unless indicated), which was HIPped at 1203 K (930 °C), and of forged bar stock, which was slowly cooled from above the beta transus, were both subsequently held at 773 K (500 °C) for times up to 5 weeks and analyzed using scanning and transmission electron microscopy and atom probe analysis. It has been shown that in the samples aged for 5 weeks at 773 K (500 °C), there is a high density of alpha2 (α₂, an ordered phase based on the composition Ti₃Al) precipitates, which are typically 5 nm in size, and a significantly smaller density was present in the slowly cooled samples. The fatigue and tensile properties of samples aged for 5 weeks at 773 K (500 °C) have been compared with those of the HIPped powder and of the forged samples which were slowly cooled from just above the transus, and although no significant difference was found between the fatigue properties, the tensile strength of the aged samples was 5 pct higher than that of the as-HIPped and slowly cooled forged samples. The ductility of the forged samples did not decrease after aging at 773 K (500 °C) despite the strength increase. Transmission electron microscopy has been used to assess the nature of dislocations generated during tensile and fatigue deformation and it has been found that not just is planar slip observed, but dislocation pairs are not uncommon in samples aged at 773 K (500 °C) and some are seen in slowly cooled Ti6Al4V.     

ESOM: An expert system for multicriteria scheduling

There exist situations in operations scheduling where the parameters of the scheduling decision are nonquantifiable, or appear as nonnumerical entries in a database. Scheduling techniques based on numerical algorithms may be difficult to use in such situations. In many service industries, the nonnumerical character arises from constraints or preference parameters associated with service tasks, service agents, and the business operation itself. The agent to task assignment problem is one of satisfying multiple objectives, by taking into account the various constraints and preferences inherent in such problems. In this paper, we describe the development of an expert system prototype called ESOM, that aims to automate the assignment decision process of a childcare referral agency. We discuss some key research issues pertaining to service scheduling in general, and to the childcare assignment problem in particular. ESOM provides useful guidelines to future researchers and practitioners interested in building expert systems for service scheduling. We demonstrate assignments made by our prototype through an application scenario.     

Hot electron transport in In (0·53) Ga (0·47) As

Monte Carlo results on the hot-electron transport coefficients of In(0·53) Ga (0·47) As are presented. The material parameters were selected by analysing the experimental hot-electron velocity-field characteristics and calculations were made by including all the relevant scattering mechanisms. Results are presented for the bulk drift velocity and diffusion coefficient and also for the velocity-field characteristics of submicron samples and 2 DEG.