On the application of proper orthogonal decomposition (POD) for in-cylinder flow analysis

Proper orthogonal decomposition (POD) is a coherent structure identification technique based on either measured or computed data sets. Recently, POD has been adopted for the analysis of the in-cylinder flows inside internal combustion engines. In this study, stereoscopic particle image velocimetry (Stereo-PIV) measurements were carried out at the central vertical tumble plane inside an engine cylinder to acquire the velocity vector fields for the in-cylinder flow under different experimental conditions. Afterwards, the POD analysis were performed firstly on synthetic velocity vector fields with known characteristics in order to extract some fundamental properties of the POD technique. These data were used to reveal how the physical properties of coherent structures were captured and distributed among the POD modes, in addition to illustrate the difference between subtracting and non-subtracting the ensemble average prior to conducting POD on datasets. Moreover, two case studies for the in-cylinder flow at different valve lifts and different pressure differences across the air intake valves were presented and discussed as the effect of both valve lifts and pressure difference have not been investigated before using phase-invariant POD analysis. The results demonstrated that for repeatable flow pattern, only the first mode was sufficient to reconstruct the physical properties of the flow. Furthermore, POD analysis confirmed the negligible effect of pressure difference and subsequently the effect of engine speed on flow structures

The mechanism of catalysis by type-II NADH : quinone oxidoreductases

Type II NADH:quinone oxidoreductase (NDH-2) is central to the respiratory chains of many organisms. It is not present in mammals so may be exploited as an antimicrobial drug target or used as a substitute for dysfunctional respiratory complex I in neuromuscular disorders. NDH-2 is a single-subunit monotopic membrane protein with just a flavin cofactor, yet no consensus exists on its mechanism. Here, we use steady-state and pre-steady-state kinetics combined with mutagenesis and structural studies to determine the mechanism of NDH-2 from Caldalkalibacillus thermarum. We show that the two substrate reactions occur independently, at different sites, and regardless of the occupancy of the partner site. We conclude that the reaction pathway is determined stochastically, by the substrate/product concentrations and dissociation constants, and can follow either a ping-pong or ternary mechanism. This mechanistic versatility provides a unified explanation for all extant data and a new foundation for the development of therapeutic strategies

The stabilisation of purified, reconstituted P-glycoprotein by freeze drying with disaccharides

The drug efflux pump P-glycoprotein (P-gp) (ABCB1) confers multidrug resistance, a major cause of failure in the chemotherapy of tumours, exacerbated by a shortage of potent and selective inhibitors. A high throughput assay using purified P-gp to screen and characterise potential inhibitors would greatly accelerate their development. However, long-term stability of purified reconstituted ABCB1 can only be reliably achieved with storage at -80 °C. For example, at 20 °C, the activity of ABCB1 was abrogated with a half-life of <1 day. The aim of this investigation was to stabilise purified, reconstituted ABCB1 to enable storage at higher temperatures and thereby enable design of a high throughput assay system. The ABCB1 purification procedure was optimised to allow successful freeze drying by substitution of glycerol with the disaccharides trehalose or maltose. Addition of disaccharides resulted in ATPase activity being retained immediately following lyophilisation with no significant difference between the two disaccharides. However, during storage trehalose preserved ATPase activity for several months regardless of the temperature (e.g. 60% retention at 150 days), whereas ATPase activity in maltose purified P-gp was affected by both storage time and temperature. The data provide an effective mechanism for the production of resilient purified, reconstituted ABCB1

Development of catalyst complexes for upgrading biomass into ester-based biolubricants for automotive applications: a review

Biomass-derived oils are recognised as the most promising renewable resources for the production of ester-based biolubricants due to their biodegradable, non-toxic and metal adhering properties. Homogeneous acid catalysts have been conventionally used in catalytic esterification and transesterification for the synthesis of ester-based biolubricants. Although homogeneous acid catalysts encounter difficulty during phase separation, they exhibit superior selectivity and good stereochemistry and regiochemistry control in the reaction. Consequently, transition metal complex catalysts (also known as homogeneous organometallic catalysts) are proposed for biolubricant synthesis in order to achieve a higher selectivity and conversion. Herein, the potential of both homogeneous transition metal complexes and heterogeneous supported metal complexes towards the synthesis of biolubricants, particularly, in esterification and transesterification, as well as the upgrading process, including hydrogenation and in situ hydrogenation–esterification, is critically reviewed

Annotated compound data for modulators of detergent-solubilised or lipid-reconstituted respiratory type II NADH dehydrogenase activity obtained by compound library screening

The energy-generating membrane protein NADH dehydrogenase (NDH-2), a proposed antibacterial drug target (see “Inhibitors of type II NADH:menaquinone oxidoreductase represent a class of antitubercular drugs” Weinstein et al. 2005 [1]), was screened for modulators of activity in either detergent-solublised or lipid reconstituted (proteolipsome) form. Here we present an annotated list of compounds identified in a small-scale screen against NDH-2. The dataset contains information regarding the libraries screened, the identities of hit compounds and the physicochemical properties governing solubility and permeability. The implications of these data for future antibiotic discovery are discussed in our associated report, “Comparison of lipid and detergent enzyme environments for identifying inhibitors of membrane-bound energy-transducing proteins” [2]

Performance and Emission Analysis of Rubber Seed Methyl Ester and Antioxidant in a Multicylinder Diesel Engine

In this study, the potential of using a nonedible biodiesel source (rubber seed oil) was explored. Rubber seed oil (RSO) is a promising nonedible source for producing a sustainable biodiesel in Malaysia. However, due to the lower oxidation stability of the produced biodiesel, which is the result of its higher unsaturation content (78.73%), an oxidation inhibitor is required. This paper examines the effect of antioxidants addition to rubber seed biodiesel (RB) on the combustion, engine performance, and emissions. Four antioxidants, namely, N,N′-diphenyl-1,4-phenylenediamine (DPPD), 2-tert-butylbenzene-1,4- diol (TBHQ), N-phenyl-1,4-phenylenediamine (NPPD), and 2(3)-tert-butyl-4-methoxyphenol (BHA), were added at concentrations of 1000 and 2000 ppm to 20% RB (RB20). The results showed that TBHQ had the greatest ability to increase the stability of RB20 followed by BHA, DPPD, and NPPD, respectively, without a significant effect on physical properties. The experiments were conducted in a 55 kW multicylinder diesel engine at full load conditions. The results showed that RB20 produced a lower brake power (BP) of 3.07%, higher brake specific fuel consumption (BSFC) of 3.68%, and higher maximum in-cylinder pressure of 6.7% compared to neat diesel. Antioxidants addition reduced the NO, heat release rate (HRR), and maximum in cylinder pressure by an average of 0.85− 4.12%, 5.78−14.74%, and 1.77−3.97%, respectively, compared to RB20. All antioxidant fuels showed a similar start of combustion (−12 °CA BTDC), but for diesel and RB20 the values were −10 and −13 °CA BTDC, respectively. However, carbon monoxide (CO) and hydrocarbon (HC) emissions increased by 10.17− 15.25% and 13.35−19.68%, respectively, compared to RB20. It can be concluded that the RB20 blend treated with antioxidants can be used in diesel engines without any further modifications

Optimization of Performance and Emissions of a Diesel Engine Fuelled with Rubber Seed-Palm Biodiesel Blends using Response Surface Method

The effects of engine speed and load, and fuel blend ratio on the emissions and performance of an IDI (indirect injection) diesel engine were investigated. A 50:50 vol. blend of rubber seed and palm oils was used for the biodiesel production to reduce costs and enhance properties. Oil acid was reduced from 33.4 to 1.42 mg KOH/g oil by esterification followed by a transesterification in a hydrodynamic cavitation reactor. Blends of 0- 40 vol. % biodiesel to a diesel with 10% increments were prepared. Statistical tool, BBD (Box-Behnken design) based on a RSM (response surface methodology) was used to assess the combined effects of variables on parameters such as BT (torque), BP (power), BSFC (brake specific fuel consumption), BTE (brake thermal efficiency), CO, CO2, NOx, EGT (exhaust gas temperature) and O2. The engine load was found to be the most influential parameter compared to the engine speed and fuel blend. The engine speed was found to have a strong effect on performance and emissions except on BT and O2. The fuel blend effect was less significant except for BSFC, BTE, CO and CO2. On average biodiesel blends showed lower BT (0.97- 1.6%), BP (0.94- 1.4%), BTE (0.76-1.5%) and CO (0.93-6.7%) but higher BSFC (0.93- 1.7%), CO2 (0.95- 1.1%), NOx (0.97- 1.2%), EGT (1.1- 1.3%) and O2 (0.3- 1.2%) compared to diesel fuel. An optimum desirability value of 0.96 was achieved with fuel blend of 18 % (biodiesel to diesel), engine speed of 2320 rpm and engine load of 82% for the tested IDI engine

Complete Genome Sequence of Pseudomonas aeruginosa K34-7, a Carbapenem-Resistant Isolate of the High-Risk Sequence Type 233

Carbapenem-resistant Pseudomonas aeruginosa is defined as a “critical” priority pathogen for the development of new antibiotics. Here we report the complete genome sequence of an extensively drug-resistant, Verona integron-encoded metallo-- lactamase-expressing isolate belonging to the high-risk sequence type 233