Crystal structure of an inulosucrase from Halalkalicoccus jeotgali B3T-a halophilic archaeal strain

Several archaea harbour genes that code for fructosyltransferase (FTF) enzymes. These enzymes have not been characterized yet at structure-function level, but are of extreme interest in view of their potential role in the synthesis of novel compounds for food, nutrition and pharmaceutical applications. In this study, 3D structure of an inulin-type fructan producing enzyme, inulosucrase (InuHj), from the archaeon Halalkalicoccus jeotgali was resolved in its apo form as well as with bound substrate (sucrose) molecule and first transglycosylation product (1-kestose). This is the first crystal structure of an FTF from halophilic archaea. Its overall five-bladed β-propeller fold is conserved with previously reported FTFs, but also shows some unique features. The InuHj structure is closer to those of Gram-negative bacteria, with exceptions such as residue E266, which is conserved in FTFs of Gram-positive bacteria and has possible role in fructan polymer synthesis in these bacteria as compared to fructooligosaccharide (FOS) production by FTFs of Gram-negative bacteria. Highly negative electrostatic surface potential of InuHj, due to a large amount of acidic residues, likely contributes to its halophilicity. The complex of InuHj with 1-kestose indicates that the residues D287 in the 4B-4C loop, Y330 in 4D-5A and D361 in the unique α2 helix may interact with longer FOSs and facilitate the binding of longer FOS chains during synthesis. The outcome of this work will provide targets for future structure-function studies of FTF enzymes, particularly those from archaea

An investigation into the effects of variable valve actuation on combustion and emissions in an SI engine

The work reported in this thesis was conducted to study the effects of variable valve actuation on combustion, emissions, and fuel economy in a modern design of 4-valve per cylinder SI engine. The use of statistically-based procedures for the design of experiments allowed a limited number of tests to be used to explore a wide region of each of the experimental variables. A series of steady-flow tests was conducted to assess the effects of valve lift on flow past the valves and the nature of any in-cylinder motion generated. Results from the former were incorporated into a filling and emptying model that allowed levels of trapped residuals and pumping work to be estimated for different valve strategies. The in-cylinder motion tests explored asymmetric valve lifts, that is to say where the two valves were opened by a different amount. These results allowed a pair of response surfaces to be established to model the intensity of both axial and barrel swirl within the cylinder over the range of valve lifts. Engine tests were conducted in two parts. The first explored the effects of changes in exhaust event phasing, intake event phasing, intake event duration, and peak intake valve lift. The design of the experiment allowed linear, quadratic, and interactions between the variables to be modelled using regression analysis. Statistical analysis allowed the most influential factors (both main effects and interactions) to be identified. Contour plots of the modelled response were used to draw conclusions about the nature of the response surface and to isolate the effects of valve opening and closure angles as well as overlap. The results were correlated with those from the steady-flow tests and from the computer model. The strategy for the second phase of tests was chosen after considering the previous results. The steady-flow tests indicated that there was considerable potential for enhancing in-cylinder motion by adopting a valve deactivation strategy and combining it with a low lift of the active intake valve. The second phase investigated the use of such a technique in conjunction with large overlaps over a range of duration of the intake valve event. The results from both phases of engine tests indicated possible strategies to reduce emissions from future engines

Hybrid sensors using laser targeting

Proposed, to the best of our knowledge, is the first extreme environment wireless all-in-one hybrid temperature plus pressure sensor using a remoted thick single crystal Silicon Carbide chip within a pressurized capsule. Analysis and experiments are reported for the pressure aspect of the sensor for pressures up to 40 atms

Wireless pressure sensor using laser targeting of silicon carbide

To the best of our knowledge, proposed is the first extreme-environment wireless pressure sensor design using a remoted single-crystal SiC chip within a pressurized capsule. A detailed theoretical analysis of the sensor system is performed, including the SiC chip's mechanical response within the pressure capsule and the pressure measurement technique's optical response based on image demagnification. The remote sensor was experimentally tested at room temperature for pressures up to 41 atm, and the sensor response is consistent with the theoretical analysis. The demonstrated sensor has a current experimental resolution of 1.17 atm with a designed maximum pressure range of 140 atm. Improved sensing resolution and range can be achieved via optimal selection of the SiC chip's dimensions and its seating in the pressure capsule. Applications for this sensor include extreme environments involving hot gases and corrosive fluids, as in power generation systems, oil field operations, and aerospace systems

Process optimization and mechanistic studies of lead (II): Aspergillus caespitosus interaction for industrial effluent treatment

The lead (II) accumulation potential of various biosorbent had been widely studied in the last few years, but an outstanding Pb(II) accumulating biomass still seems crucial for bringing the process to a successful application stage. This investigation describes the use of non-living biomass of Aspergillus caespitosus for removal of Pb from Pb(NO3)2 solution in a batch system under different experimental conditions. The highest Pb(II) sorption (351.7 ± 5.7 mg/g biomass) was observed at 600 µg/ml initial Pb concentration. Biosorption data were well defined by pseudo-second order, saturation mixed order and Langmuir isotherm models. The thermodynamic parameters: G (303 K), H and S were determined to be 4.64 kJ/mol, 75.4 kJ/mol and 26.2 J/mol-K respectively. The Pb uptake from binary solution was inhibited in the order of copper > nickel > zinc > manganese. Fourier transform infrared spectroscopy (FT-IR) characterization of Pb biosorption revealed the involvement of –SO3 and –CN groups along with other groups. The biosorbed Pb was stripped out (85.5%) using 0.01 M HCl and about 12% loss in Pb(II) sorption capacity was observed after five sorption-desorption cycles. High Pb (II) uptake (351.7 ± 5.7 mg/g biomass) by A. caespitosus proved it to be an outstanding biomaterial until now reported in literature for accumulating from solutions.Key words: Aspergillus caespitosus, Pb, Langmuir isotherm, pseudo-second-order kinetic model, FTIR, SEM, EDAX

Super high-performance MEMS fiber optic variable optical attenuator (VOA) for aerospace and commercial applications.

Fiber-optic variable optical attenuators (VOAs) are required for light power control in numerous applications such as test and instrumentation, optical fiber telecommunications, industrial fiber-optic sensing, biomedical imaging and sensing, and photonic signal processing for antennas and radar systems. The requirements for the VOA, such as dynamic range and resolution, vary depending on the application. A VOA can demonstrate high end performance when it possesses critical attributes like super resolution precision and high dynamic range. Reported in this paper is the demonstration of a hybrid analog-digital fiber-optic VOA design that employs microelectromechanical systems (MEMS) technology. The VOA demonstrates simultaneously a super high controlled dynamic range of 81 dB as well as super 0.1 dB resolution attenuation controls. Proof-of-concept experiments exhibit an optical loss of 2.5 dB and C-band operations.Fiber-optic variable optical attenuators (VOAs) are required for light power control in numerous applications such as test and instrumentation, optical fiber telecommunications, industrial fiber-optic sensing, biomedical imaging and sensing, and photonic signal processing for antennas and radar systems. The requirements for the VOA, such as dynamic range and resolution, vary depending on the application. A VOA can demonstrate high end performance when it possesses critical attributes like super resolution precision and high dynamic range. Reported in this paper is the demonstration of a hybrid analog-digital fiber-optic VOA design that employs microelectromechanical systems (MEMS) technology. The VOA demonstrates simultaneously a super high controlled dynamic range of 81 dB as well as super 0.1 dB resolution attenuation controls. Proof-of-concept experiments exhibit an optical loss of 2.5 dB and C-band operations

Super-resolution variable fiber optic attenuator instrument using digital micromirror device (DMD (TM))

Demonstrated is a super resolution, low loss, 100% repeatable and fast response digital variable fiber-optic attenuator instrument using a digital micromirror device. The attenuator design exploits beam expansion optics and a retroreflective architecture to achieve super-resolution with digital repeatability. The proof-of-concept attenuator at 1550 nm demonstrates a 41.5 dB optical attenuation range, optical insertion loss of 3.8 dB, a 1 ms maximum attenuation reset time, an optical polarization dependant loss of less than 0.07 dB, and an optical resolution range of 2.9-0.0517 mdB. The demonstrated attenuator is appropriate for fiber-optic test and instrumentation applications.Demonstrated is a super resolution, low loss, 100% repeatable and fast response digital variable fiber-optic attenuator instrument using a digital micromirror device. The attenuator design exploits beam expansion optics and a retroreflective architecture to achieve super-resolution with digital repeatability. The proof-of-concept attenuator at 1550 nm demonstrates a 41.5 dB optical attenuation range, optical insertion loss of 3.8 dB, a 1 ms maximum attenuation reset time, an optical polarization dependant loss of less than 0.07 dB, and an optical resolution range of 2.9-0.0517 mdB. The demonstrated attenuator is appropriate for fiber-optic test and instrumentation applications

Performance as a classification criterion of tourist origins and destinations

The definition of performance variables, which can be used as indicators of the results obtained/to be obtained, is a fundamental prerequisite in the carrying out of any evaluation process. Portfolio analysis has been used as a tool for the study of market segments, namely of tourist destinations. However, a review of the literature did not identify a single case where the performance variable is adjusted to the nature of the object. In fact, contrary to many other situations, the use of performance variables in absolute terms does not appear to be the most recommendable solution given that the total volume is conditioned by the size of the territory and, above all, by the number of inhabitants. In other words, for a certain level of socio-economic development, larger countries (in terms of size and number of inhabitants) will tend to have higher absolute values. Besides this, the empirical studies reviewed contain little, or no, information about competition, being temporally static. Although in some cases growth rate is used as a variable, thus presupposing the consideration of two magnitudes in two different moments in time, more than one register per object is never considered, meaning that evolutive analyses are not viable. Consequently, a performance proxy was developed which enables a direct comparison between generating countries (origins) and between destinations, regardless of the number of inhabitants. The selection of the performance proxy can depend on the object of study. In any case, it should always permit the evaluation, in general terms, of the results obtained by the destination for the set of origins under analysis and the results generated by the origin for the set of destinations under study. The proposed tool is a component of a model for the identification of priority market segments, and is constituted by a system of orthogonal axes which produces four quadrants that are distinct in terms of intensity (axis OY) and growth (axis OX) of tourist flows. The tool, like the model, can be applied to any type of destination (city, region or country) and to any market segmentation criterion (geographic, demographic, behavioural, psychographic or other). In the study reported here, the instrument is applied to the 15 Member States of the European Union (before its expansion on May 1st 2004), for the period from 1996 to 2001. Eurostat was the sole source of data for the study. The UK and Ireland are the countries classified as ‘Progressing Origins’. With 16.8% of the population, they increased their contribution from 17.7% to 21.9% and are responsible for 38.7% of the growth that occurred between 1996 and 2001. Spain, Greece and Ireland are the countries classified as ‘Progressing Destinations’. With 14.4% of the population, they increased their share of the market from 21.5% to 24.2%, capturing 35.1% of the growth that occurred between 1996 and 2001

GATA transcription factors drive initial Xist upregulation after fertilization through direct activation of a distal enhancer element

To ensure dosage compensation for X-linked genes between the sexes, one X chromosome is silenced during early embryonic development of female mammals. This process of X-chromosome inactivation (XCI) is initiated through upregulation of the RNA Xist from one X chromosome shortly after fertilization. Xist then mediates chromosome-wide gene silencing in cis and remains expressed in all cell types except the germ line and the pluripotent state, where XCI is reversed. The factors that drive Xist upregulation and thereby initiate XCI remain however unknown. We identify GATA transcription factors as potent Xist activators and demonstrate that they are essential for the activation of Xist in mice following fertilization. Through a pooled CRISPR activation screen we find that GATA1 can drive ectopic Xist expression in murine embryonic stem cells (mESCs). We demonstrate that all GATA factors can activate Xist directly via a GATA-responsive regulatory element (RE79) positioned 100 kb upstream of the Xist promoter. Additionally, GATA factors are essential for the induction of XCI in mouse preimplantation embryos, as simultaneous deletion of three members of the GATA family (GATA1/4/6) in mouse zygotes effectively prevents Xist upregulation. Thus, initiation of XCI and possibly its maintenance in distinct lineages of the preimplantation embryo is ensured by the combined activity of different GATA family members, and the absence of GATA factors in the pluripotent state likely contributes to X reactivation. We thus describe a form of regulation in which the combined action of numerous tissue-specific factors can achieve near-ubiquitous expression of a target gene