Ligand-induced structural changes in maltose binding proteins measured by atomic force microscopy

We use atomic force microscopy (AFM) based force-compression measurements to probe the ligand-induced functional conformational changes in surface-immobilized dicysteine-terminated maltose binding proteins (dicys-MBPs). The proteins are immobilized at well-defined locations directly on Au substrates using the previously reported technique of nanografting. By measuring the difference between the ligand-free and ligand-bound mechanical work performed by the AFM-tip during the protein compression, we determine the open-closed transition energy for dicys-MBPs to be DeltaE0 = (8 +/- 4) Kcal/mol. We also compare the binding kinetics of two different ligands (maltose and maltotriose) to dicys-MBPs by performing AFM-friction measurements. We show that our results are consistent with a simple model for the surface-immobilized dicys-MBPs: the protein consists of two rigid lateral lobes connected by a hinge-loaded spring.     

Modelling of photonic bandgap devices by the leaky mode propagation method

Main modelling approaches used for investigating the Photonic bandgap (PBG) devices are reviewed. In particular, the model based on Leaky Mode Propagation (LMP) method is described. A complete analysis of the propagation characteristics, including the determination of modal propagation constants, electromagnetic field harmonics and total field distribution, transmission and reflection coefficients, total forward and backward power flow in the structure, guided and radiated power, and total losses, can be carried out by a computer program based on the LMP approach. The numerical results have been validated by comparisons with those obtained by using other more complex and expensive models. The new model shows some significant advantages in terms of very low computational time, absence of any a priori theoretical assumptions and approximations, capability of simulating the actual physical behaviour of the device and fast determination of the bandgap position.Copyright © 2003 John Wiley & Sons, Ltd.     

Analytical modelling of multilayer structure electronic devices for electrothermal layout optimisation

In this paper, an analytical model for the electrothermal solution to the non‐linear 3‐D heat flow equation for multilayer structure electronic devices is proposed. Compared with previous models presented in literature, it is general and can be easily applied to a large variety of integrated devices, provided that their structure can be represented as an arbitrary number of superimposed layers with a 2‐D embedded thermal source, so as to include the effect of the package. The proposed method is independent of the specific physical properties of the layers, hence GaAs MESFETs and HEMTs as well as silicon and silicon‐on‐insulator MOSFETs and heterostructure LASERs can be analysed. Moreover, it takes into account the dependence of the thermal conductivity of all the layers on the temperature; the heat equation is solved coupled with the device current–voltage relation in order to give physical consistence to the experimental evidence that a temperature increase causes a degradation of the electrical performances and that the electrical power is not uniformly distributed. Copyright © 2001 John Wiley & Sons, Ltd.     

Evaluating energy security performance from 1990 to 2010 for eighteen countries

This study provides an index for evaluating national energy security policies and performance among the United States, European Union, Australia, New Zealand, China, India, Japan, South Korea, and the ten countries comprising the Association of Southeast Asian Nations (ASEAN). Drawn from research interviews, a survey instrument, and a focused workshop, the article first argues that energy security ought to be comprised of five dimensions related to availability, affordability, technology development, sustainability, and regulation. The article then breaks these dimensions down into 20 components and correlates them with 20 metrics that constitute a comprehensive energy security index. We find that the top three performers of our index for all data points and times are Japan, Brunei, and the United States and the worst performers Vietnam, India, and Myanmar. Malaysia, Australia, and Brunei saw their energy security improve the most from 1990 to 2010 whereas Laos, Cambodia, and Myanmar saw it decline the most. The article concludes by calling for more research on various aspects of our index and its results.     

Influence of space allowance and housing conditions on the welfare, immune response and production performance of dairy ewes

The experiment used 45 Comisana ewes, divided into 3 groups of 15. The aim was to determine the effects of two different stocking densities and two different housing conditions on welfare, and on production performance of dairy ewes. The stocking densities tested were: high stocking density (1 x 5 m2/ewe, HD group) and low stocking density (3 m2/ewe, LD group); the two housing conditions tested were: ewes housed indoors (LD group, 3 m2/ewe) and ewes allowed to use an outdoor area (LDP group, 3 m2/ewe divided into 1 x 5 m2/ewe indoors and 1 x 5 m2/ewe outdoors). At the beginning of the experiment, and then every 2 months, the cell-mediated immune status of sheep was evaluated. One month after the beginning of the experiment, and 20 d later, the ewes were injected with chicken egg albumin (OVA) to assess their humoural immune responses. Starting from the beginning of the experiment and then monthly, behavioural activities of ewes were monitored using 15-min scans. After lamb weaning, milk yield from individual ewes was measured and milk composition analysed weekly. Housing conditions (low density reared ewes indoors v. low density reared ewes with free access to an outdoor area) affected cell-mediated response, which was higher in LDP than in LD ewes. Concentrations of anti-OVA IgG were mainly influenced by space allowance, with higher antibody titres in LD than in HD ewes throughout the experiment. Both housing conditions and space allowance affected sheep behavioural activities: a greater proportion of LDP ewes displayed standing and drinking behaviours than LD ewes, and a greater proportion of LD ewes was observed walking than HD ewes. Ewes allowed access to the outdoor area had a higher protein content and lower somatic cell count in their milk, whereas reduced space allowance led to a reduction in milk yield and an increase in somatic cell count of milk. Results indicate that both increased space allowance and availability of outdoor area can improve the welfare and production performance of the lactating ewe.     

Experimental tests of a new hysteretic damper made of buckling inhibited shear panels

Metal shear panels represent a highly performing anti seismic system for medium–high rise buildings located in strong earthquake prone zones. A new configuration of dissipative shear panel is presented in the current paper. The base shear plate is made of a low-strength material, namely the heath treated EN-AW-1050A aluminium alloy, which has been already used by the authors for other types of dissipative shear panels. In this proposed new system, the main buckling modes are inhibited by the application of external devices placed in parallel to the base plate and not directly loaded by the external forces. Two shear panel samples are tested as prototypes, which are based on two different plate buckling inhibition strategies. In the former the out-of-plane displacements of only some parts of the base plate are restrained, whereas in the latter the restraining action of the external device is extended to the whole base plate. Experimental tests are presented in order to prove the performance of the proposed devices in terms of dissipative capacity and stiffness. In addition, the obtained results are compared with the ones related to other more conventional shear panel typologies, characterized by the same geometry and material, but in which buckling phenomena were mitigated by means of welded stiffeners, according to a more traditional practice.     

Process simulation of natural gas steam reforming: Fuel distribution optimisation in the furnace

This paper describes a two-step method to simulate the natural gas steam reforming for hydrogen production. The first step is to calculate reforming tube length and fuel distribution with equilibrium approach associated with heat transfer. The second step is to calculate and validate reforming performance with kinetic model. A short-cut simulation of hydrogen plant has also been performed to calculate inputs for the reformer model, such as total flow rate and composition of mixed fuel burning in the furnace chamber. Heat transfer, especially radiative heat transfer, is the key role in the steam reforming technology, due to the high heat fluxes involved. For this reason, energy modelling of the furnace chamber has been performed. The simulation evaluates the most important design variables, as tubes height, maximum tube-wall temperature, and tube pressure drop. The heat flux profile can be selected to have suitable metal temperatures to lengthen the reformer tube life. The model calculates the design parameters for reforming tube and fuel distribution among burners.     

Determination of Deoxynivalenol in Wheat Bran and Whole-Wheat Flour by Fluorescence Polarization Immunoassay

A rapid and accurate fluorescence polarization (FP) immunoassay has been optimized for the determination of deoxynivalenol (DON) in wheat bran and whole-wheat flour. A preliminary treatment with activated charcoal was used to eliminate the strong matrix effect due to highly colored interfering compounds present in raw wheat bran extracts. In particular, matrix effect was removed by adding activated charcoal to the wheat bran extract (3.5 mg/mL) and mixing for 3 min of incubation time prior to the FP immunoassay analysis. No preliminary treatment was necessary for whole-wheat flour. Average recoveries from samples spiked with DON at levels of 500, 1,000, and 1,500 μg/kg were 95 % for wheat bran and 94 % for whole-wheat flour, with relative standard deviation generally lower than 13 %. Limits of quantification of the optimized FP immunoassay were 120 μg/kg for both matrices. The overall time of analysis was lower than 15 min for wheat bran and 10 min for whole-wheat flour. Good correlations (r?>?0.971) were observed between DON contents obtained by both FP immunoassay and high-performance liquid chromatography with immunoaffinity cleanup for 37 and 23 samples of naturally contaminated wheat bran and whole-wheat flour, respectively. These results show that the FP immunoassay is suitable for high-throughput screening as well as for quantitative determination of DON in wheat bran and whole-wheat flour.     

Quality of milk and of Canestrato Pugliese cheese from ewes exposed to different ventilation regimens

Effects of ventilation regimen on the quality of ewes' milk and on proteolysis in Canestrato Pugliese cheese during ripening were studied. Cheeses were manufactured from the bulk milk of Comisana ewes subjected to three different ventilation regimens, which were designated low (LOV, 23 m3/h per ewe), moderate (MOV, 47 m3/h per ewe) and programmed ventilation regimen (PROV, 73 m3/h per ewe; fan set to maintain 70% relative humidity). Bulk milk was analysed for chemical and microbial composition, renneting parameters and plasmin-plasminogen activities. At 1, 15, 30 and 45 d of ripening, the cheeses were analysed for gross chemical composition, nitrogen fractions, and plasmin and plasminogen activities. The pH 4.6-insoluble nitrogen fractions were analysed by urea-PAGE. Free amino acid content was determined at the end of ripening. Lower concentrations of bulk milk somatic cell count (BMSCC) and of mesophilic bacteria were found in the MOV group than in the LOV and the PROV groups. A lower plasminogen (PG) to plasmin (PL) ratio (PG/PL) was observed in the MOV and PROV than in the LOV cheeses. Irrespective of treatment, PL activity in cheeses was higher at 15d of ripening, while a sudden decrease of PL and PG activities was observed at 30 d, which was associated with a marked increase in non-protein nitrogen. The peptide profile characterized in the urea-PAGE showed a greater intensity of alpha- and beta-CN hydrolysis in the MOV than in the PROV and LOV cheeses. The results provide evidence that a proper ventilation regimen is critical for optimizing the hygienic quality of milk and the proteolysis of Canestrato Pugliese cheese during ripening.