Mixed Precision Iterative Refinement with Adaptive Precision Sparse Approximate Inverse Preconditioning

Hardware trends have motivated the development of mixed precision algo-rithms in numerical linear algebra, which aim to decrease runtime while maintaining acceptable accuracy. One recent development is the development of an adaptive precision sparse matrix-vector produce routine, which may be used to accelerate the solution of sparse linear systems by iterative methods. This approach is also applicable to the application of inexact preconditioners, such as sparse approximate inverse preconditioners used in Krylov subspace methods. In this work, we develop an adaptive precision sparse approximate inverse preconditioner and demonstrate its use within a five-precision GMRES-based iterative refinement method. We call this algorithm variant BSPAI-GMRES-IR. We then analyze the conditions for the convergence of BSPAI-GMRES-IR, and determine settings under which BSPAI-GMRES-IR will produce similar backward and forward errors as the existing SPAI-GMRES-IR method, the latter of which does not use adaptive precision in preconditioning. Our numerical experiments show that this approach can potentially lead to a reduction in the cost of storing and applying sparse approximate inverse preconditioners, although a significant reduction in cost may comes at the expense of increasing the number of GMRES iterations required for convergence

Comprehensive comparison of hetero-homogeneous catalysts for fatty acid methyl ester production from non-edible jatropha curcas oil

The synthesis of biodiesel from Jatropha curcas by transesterification is kinetically controlled. It depends on the molar ratio, reaction time, and temperature, as well as the catalyst nature and quantity. The aim of this study was to explore the transesterification of low-cost, inedible J. curcas seed oil utilizing both homogenous (potassium hydroxide; KOH) and heterogenous (calcium oxide; CaO) catalysis. In this effort, two steps were used. First, free fatty acids in J. curcas oil were reduced from 12.4 to less than 1 wt.% with sulfuric acid-catalyzed pretreatment. Transesterification subsequently converted the oil to biodiesel. The yield of fatty acid methyl esters was optimized by varying the reaction time, catalyst load, and methanol-to-oil molar ratio. A maximum yield of 96% was obtained from CaO nanoparticles at a reaction time of 5.5 h with 4 wt.% of the catalyst and an 18:1 methanol-to-oil molar ratio. The optimum conditions for KOH were a molar ratio of methanol to oil of 9:1, 5 wt.% of the catalyst, and a reaction time of 3.5 h, and this returned a yield of 92%. The fuel properties of the optimized biodiesel were within the limits specified in ASTM D6751, the American biodiesel standard. In addition, the 5% blends in petroleum diesel were within the ranges prescribed in ASTM D975, the American diesel fuel standard

Colorimetric sensing of uric acid based on sawdust-deposited silver nanoparticles via an eco-friendly and cost-effective approach

Uric acid is directly linked to gout, arthritis, neurological, cardiovascular, and kidney-related disorders. It is a byproduct obtained from the breakdown of purines and a significant indicator of hyperuricemia observed in both urine and blood. In the absence of any enzyme, it's quite difficult to develop a novel, cost-effective, and clinical method for uric acid detection. Herein, we report a very simple, low-cost, and non-enzymatic method for the selective identification and quantification of uric acid using green synthesized silver nanoparticles (Ag NPs). The desired Ag NPs were synthesized by the hydrothermal method using Erythrina suberosa sawdust as a deagglomeration agent and Psidium guajava extract as a reductant. The synthesis of the sensing platform, i.e., sawdust-deposited Ag NPs, was confirmed through different techniques such as UV-Vis spectrophotometer, FTIR, XRD, EDX, and scanning electron microscopy (SEM). Sawdust can offer a good, environmentally friendly, and cost-effective strategy to overcome the problem of agglomeration in nanoparticles. The enzyme mimic, with the help of H2O2, oxidizes the colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to oxidized TMB with a blue-green color. The addition of uric acid reduces the oxidized TMB to a colorless product, resulting in a colorimetric change. For quality improvement, different reaction parameters, including pH, time, TMB, and NPs concentration, were optimized. Our proposed sensor responds in linear ranges of 0.04–0.360 μM, with a limit of quantification of 0.01 μM and a limit of detection of 0.004 μM. The suggested enzyme mimic detected uric acid in blood samples, with particular specificity in the presence of competitive analytes

Synthesis and in vitro bioactivity evaluation of new galactose and fructose ester derivatives of 5-aminosalicylic acid

Inflammatory bowel disease (IBD) is the main risk factor for developing colorectal cancer which is common in patients of all ages. 5-Aminosalicylic acid (5-ASA), structurally relat ed to the salicylates, is highly active in the treatment of IBD with minor side effects. In this study, the synthesis of galactose and fructose esters of 5-ASA was planned to evaluate the role of glycoconjugation on the bioactivity of the parent drug. The antibacterial activity of the new compounds were evaluated against two Gram-negative and two Gram-positive species of bacteria, with a notable effect observed against Staphylococcus aureus and Escherichia coli in comparisons with the 5-ASA. Cytotoxicity testing over HT-29 and 3T3 cell lines indicated that the toxicity of the new products against normal cells was significantly reduced compared with the original drug, whereas their activity against cancerous cells was slightly decreased. The anti-inflammatory activity test in RAW264.7 macrophage cells indicated that the inhibition of nitric oxide by both of the monosaccharide conjugated derivatives was slight ly improved in comparison with the non-conjugated drug

Postoperative outcomes in oesophagectomy with trainee involvement

BACKGROUND: The complexity of oesophageal surgery and the significant risk of morbidity necessitates that oesophagectomy is predominantly performed by a consultant surgeon, or a senior trainee under their supervision. The aim of this study was to determine the impact of trainee involvement in oesophagectomy on postoperative outcomes in an international multicentre setting. METHODS: Data from the multicentre Oesophago-Gastric Anastomosis Study Group (OGAA) cohort study were analysed, which comprised prospectively collected data from patients undergoing oesophagectomy for oesophageal cancer between April 2018 and December 2018. Procedures were grouped by the level of trainee involvement, and univariable and multivariable analyses were performed to compare patient outcomes across groups. RESULTS: Of 2232 oesophagectomies from 137 centres in 41 countries, trainees were involved in 29.1 per cent of them (n = 650), performing only the abdominal phase in 230, only the chest and/or neck phases in 130, and all phases in 315 procedures. For procedures with a chest anastomosis, those with trainee involvement had similar 90-day mortality, complication and reoperation rates to consultant-performed oesophagectomies (P = 0.451, P = 0.318, and P = 0.382, respectively), while anastomotic leak rates were significantly lower in the trainee groups (P = 0.030). Procedures with a neck anastomosis had equivalent complication, anastomotic leak, and reoperation rates (P = 0.150, P = 0.430, and P = 0.632, respectively) in trainee-involved versus consultant-performed oesophagectomies, with significantly lower 90-day mortality in the trainee groups (P = 0.005). CONCLUSION: Trainee involvement was not found to be associated with significantly inferior postoperative outcomes for selected patients undergoing oesophagectomy. The results support continued supervised trainee involvement in oesophageal cancer surgery

Enhancing Abiotic Stress Tolerance in Cereals Through Breeding and Transgenic Interventions

The success of plant breeding in the 20th century led to new cultivars that, to date, have provided enough food for an increasing world population (Conway and Toenniessen 1999; Mifflin 2000). The results of the Green Revolution-led in the 1960s by Henry M. Beachell andNormanE. Dotlaug—resulted in a dramatic increase in rice and wheal grain yields (Milford and Runge 2007; Ortiz et al. 2007). However, abiotic stresses and climate change are becoming increasingly serious threats to crop production worldwide at a time when food staple supply will need to be significantly higher to meet the demand of the growing human population. Water scarcity (Rockstrom et al. 2007], salinity (Rengasamy 2006). and low soil fertility (Sanchez and Swaminathan 2005) rank among the moat important abiotic stresses worldwide. Similarly, increased climatic disturbances due to global warming are causing the major stresses that necessitate crop improvements to safeguard grain supply, particularly in the developing world (Kumar 2006). Hence, genetic enhancement of cereal crops with respect to abiotic stress tolerance will be essential far ensuring grain yields in water-limited, increasingly hotter agricultural zones, particularly If these conditions combine with poor and saline soils, conditions that prevail in parts of the developing world. Crop breeding for adaptation to abiotic stress-prone environments remains a challenging task, not least because of the complexity of the stress-adaptive mechanisms in plants and particularly cereal crops, which are the staple of most of the world's population (Reynolds et al. 2005}

Transient Stability Enhancement of Power System Using UPFC (Unified Power Flow Controller)

International audienceIn the power grid system, the prime subjects are to transmit power with supreme power factor and high power quality, supreme transient stability, economical and minimum risk of system failure. The constantly growth of electrical power demands and loads, particularly non-linear loads making the power system network become more obscure to operate and the system becomes unstable with large power flows without proper control and operation. The development in power system with time have brings new challenges and sometimes it is tough to operate system in stable condition due to complex system network. Though, on the other side there is vast development been made in power electronics, which helps the power system to continue in stable condition during most horrible condition occurred due to fault. One of the creation of power electronics is FACTS technology. FACTS (Flexible Alternating Current Transmission Systems) devices are created on power electronics and other dynamic controllers that provide control of one or more AC transmission system parameters to enhance controllability and growth power transfer capability. One way to enhance the power system control is by applying FACTS controller such UPFC (Unified Power Flow Controller). UPFC can control voltage, impedance and phase at alike time. The UPFC control scheme for the grid connected power system is simulated by MATLAB/PSAT in power system block set. By means of IEEE 9 bus power system network, the effectiveness of UPFC are tested by applying the 3-phase fault at dissimilar buses and evaluated the performance of FACTS devices in IEEE nine bus power system during fault condition

SYNTHETIC APERTURE RADAR: PRINCIPLES AND APPLICATIONS

In this paper an introduction to synthetic aperture radar is presented. Synthetic aperture radar is a relatively new remote sensing platform and the technology has matured a lot in the last two decades. This paper introduces the concepts behind SAR principles as well as the major areas where this new technology has shown additional information

Experimental investigations of the interface between steam and water two phase flows

Hydrodynamic instabilities play an important role in the design of those systems operated at high temperature and pressure. The creation and propagation of Kelvin–Helmholtz (KH) instabilities has been experimentally investigated here for the first time in condensable fluids i.e. steam and water. Generally, in case of these condensable fluids the instabilities are so much short lived that it’s very difficult to record them. Here the instabilities occurred in the close vicinity of the steam–water interface, were attributed mainly to the temperature fluctuations of micro scale or less. Supersonic steam was injected inside the subcooled water at inlet pressure varying from 1.5 bar to 3.0 bar by using a specially designed supersonic nozzle, whereas temperature of water inside the vessel was raised from 30 �C to 60 �C at an increment of 50 each. Kelvin–Helmholtz instabilities in the form of minor as well as amplified transient temperature fluctuations were recorded using a specially designed apparatus that uses LM35 sensors and data acquisition system. This system is capable to record temperatures at a rate of one millisecond and was also capable to record the temperatures anywhere inside the vessel. It was also found out that the instabilities created at the interface propagated towards the axis of the geometry as well as these instabilities were strongly affected by change in tank water temperature and inlet pressur