Regulation of an Escherichia coli/mammalian chimeric carbamoyl-phosphate synthetase

Carbamoyl-phosphate synthetase (CPSase) consists of a 120-kDa synthetase domain (CPS) that makes carbamoyl phosphate from ATP, bicarbonate, and ammonia usually produced by a separate glutaminase domain. CPS is composed of two subdomains, CPS.A and CPS.B. Although CPS.A and CPS.B have specialized functions in intact CPSase, the separately cloned subdomains can catalyze carbamoyl phosphate synthesis. This report describes the construction of a 58-kDa chimeric CPSase composed of Escherichia coli CPS.A catalytic subdomains and the mammalian regulatory subdomain. The catalytic parameters are similar to those of the E. coli enzyme, but the activity is regulated by the mammalian effectors and protein kinase A phosphorylation. The chimera has a single site that binds phosphoribosyl 5'-pyrophosphate (PRPP) with a dissociation constant of 25 microM. The dissociation constant for UTP of 0.23 mM was inferred from its effect on PRPP binding. Thus, the regulatory subdomain is an exchangeable ligand binding module that can control both CPS.A and CPS.B domains, and the pathway for allosteric signal transmission is identical in E. coli and mammalian CPSase. A deletion mutant that truncates the polypeptide within a postulated regulatory sequence is as active as the parent chimera but is insensitive to effectors. PRPP and UTP bind to the mutant, suggesting that the carboxyl half of the subdomain is essential for transmitting the allosteric signal but not for ligand binding.     

Conceptualizing development in information and communication technology for development (ICT4D)

ABSTRACT

ICT4D research is faced with the challenge of rapidly changing technologies and increasingly complex social dynamics and development processes. We argue that ICT4D research requires a more acute sense of where our research is situated within a broader picture of development, e.g. with a better understanding of development processes, their ideological nature, the power structures and driving forces, and the mechanisms through which ICTs may be embedded in and shape these processes. Such a reflexivity is crucial not least in justifying our claims of contribution, but also in understanding the implications and potential impact of our research and practice. This editorial seeks to explore key conceptual components in ICT4D and their relationships, including dimensions of development, perspectives of development, conceptions of artefacts, and theory of change. A tentative conceptual schema is presented that connects these conceptual components.     

Electrospun Differential Wetting Membranes for Efficient Oil–Water Separation

Separation of low viscous oil from water has attracted immense attention in recent times due to the ever‐increasing amount of oily industrial wastewater discharge and frequent oil spill accidents. Hence, there is a persistent demand for the fabrication of robust oil–water separation membranes. Herein, robust oil–water separation membranes are successfully fabricated by direct electrospinning of poly(vinylidene fluoride‐co‐hexafluoropropylene) and fluorinated polyhedral oligomeric silsesquioxane composite mixture. These hybrid membranes exhibit differential wetting (highly hydrophobic/superoleophilic) behavior for water and oil. The contact angle made by water and low viscous oil (hexane) with the membrane are measured to be 145 and 0° respectively. The nanofiber membranes efficiently separate low viscous oil from water in a single‐step with separation efficiency of nearly 100%. Furthermore, the results demonstrate that the membranes are robust and durable exhibiting differential wettability even after several oil–water separation cycles. The results reveal the potential of their use for real‐time industrial wastewater treatment applications.

     

压榨毛布的生产、设计和应用

福伊特造纸织物在欧洲、美国、中国和印度拥有18个生产运行中心,是世界造纸织物制造业的龙头之一.本文介绍了压榨毛布的生产和适应纸机运行的毛布的设计和运用标准及根据压榨部的需要来设计毛布的方法.     

Effect of milk protein standardisation using buffalo milk protein co-precipitates on the texture,composition and yield of paneer

Buffalo milk was utilised for preparing paneer samples after standardisation of protein:fat ratio to 0.68 with the addition of buffalo milk protein co-precipitates (BMPC). These paneer samples along with control paneer (from buffalo milk) were analysed for yield, composition, microstructure, sensory, texture profile and protein loss in whey during manufacture. Paneer prepared using BMPC was considerably higher in yield and recovery of total solids, protein and calcium content than control paneer and could withstand the frying conditions in terms of retention of shape and integrity. Texture profile analysis and microstructure evaluation revealed the differences in textural properties of paneer samples prepared using BMPC with control paneer.     

HIV/AIDS reporting systems in Mozambique: The theoretical and empirical challenges of “representations”

Acquired immunodeficiency syndrome is a disease with profound effects on the global society, as it affects individual lives, communities, societies, and even nations. As governments try to gear up on the war against this pandemic, an issue of importance pertains to the use of information systems. The systems are used to collect data on the prevalence of the disease, and analyze and transmit the data from the lower levels of the health administration where the testing is done to the higher levels of national policy making where different kinds of interventions are designed. In this article, we argue that the manner in which the representation of the disease is constructed is an important area of concern as it shapes the picture of the disease prevalence and influences how these statistics then get used for the planning of interventions such as supplying drugs and pro-health campaigns. Drawing from the domain of Science and Technology Studies (STS), with a focus on Bruno Latour's (1999) ideas of “circulating reference” we first develop the theoretical notion of representation, and then apply it to an empirical analysis of the reporting systems, both paper- and computer-based, of HIV/AIDS in Mozambique. The successive movements of information about HIV/AIDS prevalence across the various administrative levels are seen as translations that are being constructed through the communication and work practices of the health care workers at different levels, and are shaped by the political interests of the different stakeholders involved, including international agencies and national health authorities. Latour's notion of circulating reference is drawn upon to analyze the question of what is lost, what is gained, and what remains invariant through the successive stages of translation in the construction and use of the representation. © 2005 Wiley Periodicals, Inc.     

Role of ICTs in participatory development: An Indian experience

Participation of local communities has been important at least in two domains: (a) rural development processes in developing countries and (b) information systems design. The issue of participation becomes especially important in the contemporary contexts in which the use of information and communication technologies (ICTs) is being integrated within rural development initiatives in developing countries, for example in e-governance. This article attempts to synthesize the issues around participation from both IS and development studies literature in order to identify four key problematic areas: viz., (a) who defines the participation agenda, (b) what capabilities do stakeholders have to participate and how can this be strengthened, (c) what is the role of institutional conditions in enabling effective participation, and (d) how do local participatory processes experiences get integrated into broader networks to become sustainable. These four themes provide a theoretical framework to analyze how the use of ICTs is reconfiguring the dynamics between participation, rural development, and ICTs. This framework is applied in the context of an ICT initiative for rural development in India. Implications for both theory and practice are developed based on the need to judiciously integrate both structural and behavioral approaches to participation. © 2007 Wiley Periodicals, Inc.     

Detection of Asian dust storms from geostationary satellite observations of the INSAT-3D imager

Asian dust storm outbreaks significantly influence air quality, weather, and climate. Therefore, it is desirable to have qualitative and quantitative information on the time, location, and coverage of these outbreaks at high spatial and temporal resolution. The imager on board the Indian metrological geostationary satellite INSAT-3D observes Asia at a temporal resolution of 30 min and a spatial resolution of 1, 4, 8, and 4 km in the visible, middle infrared (MIR), water vapour (WV), and thermal infrared (TIR) bands, respectively. In this article, an algorithm is described for detecting desert dust storms from INSAT-3D imager data. The algorithm described here is a combination of various pre-existing methods such as infrared split-window, MIR and TIR brightness temperature difference, and visible to MIR reflectance ratio, which are based on the fact that dust exhibits features of spectral dependence and contrast over the visible, MIR, and TIR spectrum that are different from clouds, surface, and clear-sky atmosphere. Using the Atmospheric Infrared Sounder (Aqua/AIRS) dust score as proxy, INSAT-3D dust storm products were tested under different scenarios such as dust storms and dust transport in Asia. TIR observations from the geostationary platform of INSAT-3D allows computation of the infrared difference dust index (IDDI), which gives a quantitative measure of dust loading relative to clear atmosphere. Moreover, due to the high temporal resolution (30 min) of INSAT-3D observations, INSAT-3D-derived dust products allow more precise monitoring of dust transportation as compared with dust products derived from polar satellite observations.     

Electrical characterization of interface states in Ni/n-Si(111) Schottky diodes from (C-V) characteristics

Experiments have been performed on Ni/n-Si(111) Schottky diodes fabricated by the vacuum vapor deposition of Ni at 10⁻⁵ Torr pressure on an n-type «111å oriented silicon wafer. Measured current-voltage and capacitance-voltage characteristics in range frequency range 10 kHz-1 MHz have been analysed. Interface states parameters have been extracted from (C-V) characteristics using a metal-thin interfacial layer-semiconduct (MIS) structure model. The interface states density has been found to be in the range of 10¹¹ cm⁻² eV⁻¹ with a peak in the band gap of Si at about 0·51 eV below the conduction band edge.     

Mirage formation in the thermal region

Formation of a mirage in the 8-12-μm band has been observed with a high-resolution thermal camera designed and developed by us. Thermal imagery recorded under actual field conditions is presented to illustrate the mirage phenomenon. Further analysis is in progress to estimate the effect of mirages in this waveband for civil and military applications.