A review of natural convection and heat transfer in attic-shaped space

This paper presents a review of studies on natural convection heat transfer in the triangular enclosure namely, in attic-shaped space. Much research activity has been devoted to this topic over the last three decades with a view to providing thermal comfort to the occupants in attic-shaped buildings and to minimising the energy costs associated with heating and air-conditioning. Two basic thermal boundary conditions of attic are considered to represent hot and cold climates or day and night time. This paper also reports on a significant number of studies which have been performed recently on other topics related to the attic space, for example, attics subject to localized heating and attics filled with porous media.     

Experimental investigation and empirical modeling of the dry electric discharge machining process

Dry electric discharge machining (EDM) is an environment-friendly modification of the oil EDM process in which liquid dielectric is replaced by a gaseous medium. In the current work, parametric analysis of the process has been performed with tubular copper tool electrode and mild steel workpiece. Experiments have been conducted using air as the dielectric medium to study the effect of gap voltage, discharge current, pulse-on time, duty factor, air pressure and spindle speed on material removal rate (MRR), surface roughness (R_a) and tool wear rate (TWR). First, a set of exploratory experiments has been performed to identify the optimum tool design and to select input parameters and their levels for later stage experiments. Empirical models for MRR, R_a and TWR have then been developed by performing a designed experiment based on the central composite design of experiments. Response surface analysis has been done using the developed models. Analysis of variance (ANOVA) tests were performed to identify the significant parameters. Current, duty factor, air pressure and spindle speed were found to have significant effects on MRR and R_a. However, TWR was found to be very small and independent of the input parameters.     

Enzymatic hydrolysis and fermentation of lime pretreated wheat straw to ethanol

BACKGROUND: The objective of this work is to develop an efficient pretreatment method that can help enzymes break down the complex carbohydrates present in wheat straw to sugars, and to then ferment of all these sugars to ethanol. RESULTS: The yield of sugars from wheat straw (8.6%, w/v) by lime pretreatment (100 mg g^?1 straw, 121 °C, 1 h) and enzymatic hydrolysis (45 °C, pH 5.0, 120 h) using a cocktail of three commercial enzyme preparations (cellulase, β‐glucosidase, and xylanase) at the dose level of 0.15 mL of each enzyme preparation g^?1 straw was 568 ± 13 mg g^?1 (82% yield). The concentration of ethanol from lime pretreated enzyme saccharified wheat straw (78 g) hydrolyzate by recombinant Escherichia coli strain FBR5 at pH 6.5 and 35 °C in 24 h was 22.5 ± 0.6 g L^?1 with a yield of 0.50 g g^?1 available sugars (0.29 g g^?1 straw). The ethanol concentration was 20.6 ± 0.4 g L^?1 with a yield of 0.26 g g^?1 straw in the case of simultaneous saccharification and fermentation by the E. coli strain at pH 6.0 and 35 °C in 72 h. CONCLUSION: The results are important in choosing a suitable pretreatment option for developing bioprocess technologies for conversion of wheat straw to fuel ethanol. Copyright © 2007 Society of Chemical Industry     

Influence of two apo A4 polymorphisms at codons 347 and 360 on non-fasting plasma lipoprotein-lipids and apolipoproteins in Asian Indians

The spi gene of Streptococcus pneumoniae was cloned and its nucleotide sequence was determined. It encodes a protein of 204 amino acids that is homologous to bacterial signal peptidase I proteins. The S. pneumoniae protein contains all of the conserved amino acid sequence motifs previously identified in this enzyme from both prokaryotic and eukaryotic sources. Sequence comparisons revealed several additional motifs characteristic of the enzyme. The cloned S. pneumoniae gene complemented an Escherichia coli mutant defective in its leader peptidase gene. Expression of the spi gene in S. pneumoniae appeared to be essential for viability. The cloned gene was shown to produce a polypeptide of approximately 20 kDa. Overproduction of the S. pneumoniae spi gene in an E. coli expression system gave a native protein product, soluble in the presence of a non-ionic detergent, which should be amenable to structural determination.     

Validation of caregiver interviews to diagnose common causes of severe neonatal illness

The objective of this study was to validate retrospective caregiver interviews for diagnosing major causes of severe neonatal illness and death. A convenience sample of 149 infants aged < 28 days with one or more suspected diagnoses of interest (low birthweight/severe malnutrition, preterm birth, birth asphyxia, birth trauma, neonatal tetanus, pneumonia, meningitis, septicaemia, diarrhoea, congenital malformation or injury) was taken from patients admitted to two hospitals in Dhaka, Bangladesh. Study paediatricians performed a standardised history and physical examination and ordered laboratory and radiographic tests according to study criteria. With a median interval of 64.5 days after death or hospital discharge, caregivers of 118 (79%) infants were interviewed about their child's illness. Using reference diagnoses based on predefined clinical and laboratory criteria, the sensitivity and specificity of particular combinations of signs (algorithms) reported by the caregivers were ascertained. Sufficient numbers of children with five reference standard diagnoses were studied to validate caregiver reports. Algorithms with sensitivity and specificity > 80% were identified for neonatal tetanus, low birthweight/severe malnutrition and preterm delivery. Algorithms with specificities > 80% for birth asphyxia and pneumonia had sensitivities < 70%, or alternatively had high sensitivity with lower specificity. In settings with limited access to medical care, retrospective caregiver interviews provide a valid means of diagnosing several of the most common causes of severe neonatal illness and death.     

A self-organizing fuzzy logic based protective relay-an applicationto power transformer protection

In the paper the fuzzy logic based multi-criteria protective relay for a three-phase power transformer is presented. Twelve criteria used to stabilize the relay are introduced and integrated by means of multi-objective decision-making methods. The introduced protection scheme contains several internal functions and coefficients which are subject to off-line pre-installation self-setting. Three unique procedures are delivered for self-adjusting the relay, and thus, making it self-organized. The results of testing show significant gains in both sensitivity and selectivity of the self-organized relay compared with traditional approaches     

Meniscal allograft transplantation for unicompartmental arthritis of the knee

Sixty-seven meniscal allografts were transplanted in the knees of 63 patients between 1988 and 1994. Before surgery, all patients experienced refractory disabling knee pain secondary to a prior total meniscectomy with advanced unicompartmental osteoarthritic changes as verified by arthroscopy. At a mean followup of 31 months (range, 1.0-5.5 years), 58 knees (86.6%) attained a good to excellent results-Twenty-one knees received isolated meniscal allografts, with 19 achieving good to excellent results (90.5%). Five knees received a medial or lateral meniscal allograft with an anterior cruciate ligament reconstruction, and 4 (80.0%) obtained good to excellent results. Thirty-four knees received a meniscal allograft in combination with either a valgus high tibial osteotomy, varus high tibial osteotomy, or varus distal femoral osteotomy to correct for preoperative varus or valgus deformities, with 29 (85.3%) attaining good to excellent results. The remaining 7 knees underwent a combined medial meniscal allograft, valgus high tibial osteotomy, and anterior cruciate ligament reconstruction with 6 (85.7%) attaining good to excellent results. The most frequent complication was a traumatic posterior horn tear in 6 knees at a mean of 21 months after surgery (range, 9-43 months), most likely the consequence of unsuccessful healing of the posterior horn of the graft.     

Processing blackcurrants dramatically reduces the content and does not enhance the urinary yield of anthocyanins in human subjects

Blackcurrant (BC) fruits are a rich source of biologically active anthocyanins but little is known of the anthocyanin content of commonly consumed BC products or how processing affects the absorption. We report that whereas fresh and frozen whole BC were a rich source of anthocyanins, containing 897 and 642 mg (100 g FW)⁻¹ of total anthocyanins the levels in all other products were substantially lower (0.05–10.3% of the levels in fresh fruit). Further, when the absorption and excretion of BC was assessed in volunteers consuming a portion (100 g) of frozen whole BC (642 mg total anthocyanins) and, 300 g of a BC drink made by diluting concentrated syrup (33.6 mg total anthocyanins), only small quantities of BC anthocyanins were excreted in urine (fruit, 0.053 ± 0.022%; drink, 0.036 ± 0.043%; mean percent urinary yield ± SD) and they were not detected in plasma. These data indicate that fresh and frozen BC, but not processed products, are rich sources of anthocyanins but, regardless of the food source, these anthocyanins are poorly bioavailable.     

Thermodynamically Stable SiwCxNyOz Polymer-Like, Amorphous Ceramics Made from Organic Precursors

This communication reports new results on the enthalpy of formation of pseudo-amorphous ceramic compounds constituted from silicon, carbon, oxygen, and nitrogen (SiCNO), made from the polymer route. Again, like the SiCO materials, although with one exception, the enthalpy of formation from crystalline components (SiO₂ cristobalite, β-Si₃N₄, SiC, and excess C) is negative. Some of the alloyed oxygen–nitrogen compositions yield enthalpies that are much more negative (∼100 kJ/g·atom) in comparison with compositions that contain mainly oxygen or nitrogen (∼20 kJ/g·atom). The exception, having a N/O ratio near 2, has a positive value for the enthalpy. This may reflect the presence of nanoclusters of stoichiometric Si₂N₂O instead of the pseudo-amorphous nanodomain structure seen for the other samples.     

A simplification of a real‐time verification problem

We revisit the problem of real‐time verification with dense‐time dynamics using timeout and calendar‐based models and simplify this to a finite state verification problem. We introduce a specification formalism for these models and capture their behaviour in terms of semantics of timed transition systems. We discuss a technique, which reduces the problem of verification of qualitative temporal properties on infinite state space of a large fragment of these timeout and calender‐based transition systems into that on clock‐less finite state models through a two‐step process comprising of digitization and finitary reduction. This technique enables us to verify safety invariants for real‐time systems using finite state model checking avoiding the complexity of infinite state (bounded) model checking and scale up models without applying techniques from induction‐based proof methodology. In the same manner, we verify timeliness properties. Moreover, we can verify liveness for real‐time systems, which are not possible by using induction with infinite state model checkers. Copyright © 2016 John Wiley & Sons, Ltd.