Solution Structure and Constrained Molecular Dynamics Study of Vitamin B12 Conjugates of the Anorectic Peptide PYY(3–36)

Vitamin B₁₂–peptide conjugates have considerable therapeutic potential through improved pharmacokinetic and/or pharmacodynamic properties imparted on the peptide upon covalent attachment to vitamin B₁₂ (B₁₂). There remains a lack of structural studies investigating the effects of B₁₂ conjugation on peptide secondary structure. Determining the solution structure of a B₁₂–peptide conjugate or conjugates and measuring functions of the conjugate(s) at the target peptide receptor may offer considerable insight concerning the future design of fully optimized conjugates. This methodology is especially useful in tandem with constrained molecular dynamics (MD) studies, such that predictions may be made about conjugates not yet synthesized. Focusing on two B₁₂ conjugates of the anorectic peptide PYY(3–36), one of which was previously demonstrated to have improved food intake reduction compared with PYY(3–36), we performed NMR structural analyses and used the information to conduct MD simulations. The study provides rare structural insight into vitamin B₁₂ conjugates and validates the fact that B₁₂ can be conjugated to a peptide without markedly affecting peptide secondary structure.     

Sustainability of biofuels in Latin America: Risks and opportunities

Several Latin American countries are setting up biofuel programmes to establish alternative markets for agricultural commodities. This is mainly triggered by the current success of Brazilian bioethanol production for the domestic market and for export. Furthermore, the global biofuel market is expected to increase due to ambitious biofuel programmes in the EU and in the USA. Colombia, Venezuela, Costa Rica and Guatemala are focusing on bioethanol production from sugarcane whereas biofuel production in Argentina is based on soy biodiesel. Recent developments of the biofuel sector take place extremely rapid especially in Argentina, which became one of the five largest biodiesel producers in the world in 2008. Till date no specific biofuel sustainability certification systems have been implemented in Latin American, as well as on global level. This fact and the predominant use of food crops for biofuel production raise concerns about the sustainability of biofuel production related to environmental and social aspects. This paper provides an overview of the hotspots of conflicts in biofuel production in Latin America. It investigates presently available sustainability tools and initiatives to ensure sustainable biofuel production in Latin America. Finally, it provides an outlook on how to integrate sustainability in the Latin American biofuel sector.     

Characterization of emissions from burning incense

The primary objective of this study was to improve the characterization of particulate matter emissions from burning incense. Emissions of particulate matter were measured for 23 different types of incense using a cyclone/filter method. Emission rates for PM2.5 (particulate matter less than 2.5 microm in aerodynamic diameter) ranged from 7 to 202 mg/h, and PM2.5 emission factors ranged from 5 to 56 mg/g of incense burned. Emission rates were also determined using an electrical low pressure impactor (ELPI) and a small electrostatic precipitator (ESP), and emission rates were compared to those determined using the cyclone/filter method. Emission rates determined by the ELPI method were consistently lower than those determined by the cyclone/filter method, and a linear regression correlation was found between emission rates determined by the two methods. Emission rates determined by the ESP method were consistently higher than those determined by the cyclone/filter method, indicating that the ESP may be a more effective method for measuring semivolatile particle emissions. A linear regression correlation was also found between emission rates determined by the ESP and cyclone/filter methods. Particle size distributions were measured with the ELPI, and distributions were found to be similar for most types of incense that were tested. Size distributions by mass typically ranged from approximately 0.06 to 2.5 microm in aerodynamic diameter, with peak values between 0.26 and 0.65 microm. Results indicated that burning incense emits fine particulate matter in large quantities compared to other indoor sources. An indoor air quality model showed that indoor concentrations of PM25 can far exceed the outdoor concentrations specified by the US EPA's National Ambient Air Quality Standards (NAAQS), so incense smoke can pose a health risk to people due to inhalation exposure of particulate matter. Emissions of carbon monoxide (CO), nitric oxide (NO), and sulfur dioxide (SO2) were also measured for seven types of incense. Emission rates of the gaseous pollutants were sufficient to cause indoor concentrations, estimated using the indoor air quality model, to exceed the outdoor concentrations specified by the NAAQS under certain conditions. However, the incense samples that were tested would fill a room with thick smoke under these conditions.     

A Bubble Propagation Model for Pipeline Performance

Pipelining is a very commonly used implementation technique whereby multiple operations are overlapped in their successive phases of execution. An identifiable phase of an operation execution constitutes a pipe stage. Ideally, the time required to complete any of the phases does not exceed 1 clock cycle. In practice, quite often one or more of the pipeline stages take longer than 1 cycle to process the data. Such a stage is considered stalled or frozen, and during this period, instead of transmitting some intermediate result to the following stage, the stalled stage is said to be transmitting bubbles. This paper proposes an analytical model for predicting pipeline performance based on reception, generation, and transmission of these bubbles. The model proposed is shown to be an effective tool for estimating overall performance of small pipelines (5 to 6 stages deep) using the delay distributions of individual stages. The proposed model is an order of magnitude faster than the corresponding simulations. It provides the complete delay distribution (instead of just the average) of the overall performance. Also, the model is considerably less computationally complex than alternative exact analytical approaches such as the discrete-time Markov model.     

Physicochemical properties of ready‐to‐eat extruded nixtamalized maize‐based snacks enriched with grasshopper

The aim of this research was to prepare an extruded snack based on nixtamalized maize flour (Zea mays L.) (NMF) enriched with grasshopper meal (Sphenarium purpurascens Ch.) (GM) using a single screw extruder with a compression screw ratio of 3:1. A central experimental design comprising three independent variables, namely, extrusion temperature (T = 120–180 °C), feed moisture content (FMC = 18–22 g/100 g) and the grasshopper meal proportion (GMP = 0–40 g/100 g), was used. Increasing T decreased (P < 0.05) the expansion index (EI), bulk density (BD) and hardness (H). Increasing the FMC increased (P < 0.05) the EI. Increasing the GMP decreased (P < 0.05) the EI, H and water absorption index (WAI) and increased (P < 0.05) the BD and total colour difference (ΔE). The treatments that resulted in better general acceptability were those that contained a lower GMP. An extruded snack acceptable to the consumer can be obtained from a blend of NMF and GM, and up to 8.11 g/100 g of GM can be incorporated without affecting the physicochemical properties and acceptance of the snack.     

Neutral beam deployment on DEMO and its influence on design

The demands on the neutral beam heating and current drive system of a DEMO device exceed those of existing fusion experiments by several orders of magnitude. By predicting possible power waveforms it is possible to analyse the technological advances necessary to achieve a system relevant to deployment on a power plant. Achieving the necessary efficiency will require simultaneous improvements in beam current density, neutralization efficiency and beam transmission. Considering the deployment on the tokamak vessel shows no major disruption to the tritium breeder blanket and no requirement to reach a high packing density of injectors. The thermal management of components subjected to low heat flux for many hours is considered and it is shown that radiation cooling can be exploited to control the temperature of such items.     

Friction stir welding of aluminium casting alloys

The results of testing friction stir welding quality in relation to EN AC-43200 (AK9) and EN AC-45000 (AK64) aluminium casting alloys are presented. The test joints were made with the use of a welding machine constructed on the basis of numerically controlled milling machines. The assessment of the joint quality was made based on visual inspection, mechanical testing, weldment structure analysis and hardness tests. The purpose of the investigation was to discover the possibility of friction stir welding of casting alloys and the influence of welding conditions on joint properties and structure. The test results show good weldability of aluminium casting alloys by the FSW method. Sound welds can be obtained in a relatively wide range of welding parameters while the weld strength is satisfactory. In order to obtain the highest quality joints, the workpieces must be pressed onto the other, while the welding process cannot run with excessively high speed. The best mechanical properties of the joints were achieved when the friction process was conducted at a rotational speed of the mixing tool of 900 rpm.     

Adaptive transform skipping for improved coding of motion compensated residuals

New generations of video compression algorithms, such as those included in the under development High Efficiency Video Coding (HEVC) standard, provide substantially higher compression compared to their ancestors. The gain is achieved by improved prediction of pixels, both within a frame and between frames. Novel coding tools that contribute to the gain provide highly uncorrelated prediction residuals for which classical frequency decomposition methods, such as the discrete cosine transform, may not be able to supply a compact representation with few significant coefficients. To further increase the compression gains, this paper proposes transform skip modes which allow skipping one or both 1-D constituent transforms (i.e., vertical and horizontal), which is more suitable for sparse residuals. The proposed transform skip mode is tested in the HEVC codec and is able to provide bitrate reductions of up to 10% at the same objective quality when compared with the application of 2-D block transforms only. Moreover, the proposed transform skip mode outperforms the full transform skip currently investigated for possible adoption in the HEVC standard.     

Resolution improvement in two-photon fluorescence microscopy with a single-mode fiber

The dependence of spectral broadening of an ultrashort-pulsed laser beam on the fiber length and the illumination power is experimentally characterized in order to deliver the laser for two-photon fluorescence microscopy. It is found that not only the spectral width but also the spectral blue shift increases with the fiber length and illumination power, owing to the nonlinear response in the fiber. For an illumination power of 400 mW in a 3-m-long single-mode fiber, the spectral blue shift is as large as 15 nm. Such a spectral blue shift enhances the contribution from the short-wavelength components within the pulsed beam and leads to an improvement in resolution under two-photon excitation, whereas the efficiency of two-photon excitation is slightly reduced because of the temporal broadening of the pulsed beam. The experimental measurement of the axial response to a two-photon fluorescence polymer block confirms this feature.