Design,Synthesis, and Self-Assembly Studies of a Suite of Monodisperse,Facially Amphiphilic,Protein–Dendron Conjugates

The custom design of protein–dendron amphiphilic macromolecules is at the forefront of macromolecular engineering. Macromolecules with this architecture are very interesting because of their ability to self-assemble into various biomimetic nanoscopic structures. However, to date, there are no reports on this concept due to technical challenges associated with the chemical synthesis. Towards that end, herein, a new chemical methodology for the modular synthesis of a suite of monodisperse, facially amphiphilic, protein–dendron bioconjugates is reported. Benzyl ether dendrons of different generations (G1–G4) are coupled to monodisperse cetyl ethylene glycol to form macromolecular amphiphilic activity-based probes (AABPs) with a single protein reactive functionality. Micelle-assisted protein labeling technology is utilized for site-specific conjugation of macromolecular AABPs to globular proteins to make monodisperse, facially amphiphilic, protein–dendron bioconjugates. These biohybrid conjugates have the ability to self-assemble into supramolecular protein nanoassemblies. Self-assembly is primarily mediated by strong hydrophobic interactions of the benzyl ether dendron domain. The size, surface charge, and oligomeric state of protein nanoassemblies could be systematically tuned by choosing an appropriate dendron or protein of interest. This chemical method discloses a new way to custom-make monodisperse, facially amphiphilic, protein–dendron bioconjugates.     

Ocular recognition databases and competitions: a survey

The use of the iris and periocular region as biometric traits has been extensively investigated, mainly due to the singularity of the iris features and the use of the periocular region when the image resolution is not sufficient to extract iris information. In addition to providing information about an individual’s identity, features extracted from these traits can also be explored to obtain other information such as the individual’s gender, the influence of drug use, the use of contact lenses, spoofing, among others. This work presents a survey of the databases created for ocular recognition, detailing their protocols and how their images were acquired. We also describe and discuss the most popular ocular recognition competitions (contests), highlighting the submitted algorithms that achieved the best results using only iris trait and also fusing iris and periocular region information. Finally, we describe some relevant works applying deep learning techniques to ocular recognition and point out new challenges and future directions. Considering that there are a large number of ocular databases, and each one is usually designed for a specific problem, we believe this survey can provide a broad overview of the challenges in ocular biometrics.

     

Various strategies for reducing Nox emissions of biodiesel fuel used in conventional diesel engines: A review

Energy demand, decreasing fossil fuel reserves, and health-related issues about pollutants have led researchers to search for renewable alternative fuels to either partially or fully replace fossil fuels. Among many alternative fuels, biodiesel became one of the most popular choices due to similar properties to that of conventional diesel. Biodiesel produces slightly lower brake thermal efficiency compared to that of conventional biodiesel, but has an advantage of reduced emissions of CO₂, CO, HC, and smoke. However, biodiesel shows higher NOx emission which, when used in increased biodiesel market, may become a serious problem. Various strategies were attempted by different researcher to reduce NOx emissions. In this paper, various strategies, adapted for reducing NOx emissions of biodiesel fuel used in diesel engines for automobile applications, are reviewed and discussed. The strategies are grouped into three major groups, namely combustion treatments, exhaust after-treatments, and fuel treatments. Among various strategies discussed, fuel treatments, such as low temperature combustion, mixing fuel additives and reformulating fuel composition, reduce NOx emission without compromising other emission and performance characteristics and they seem to be promising for future biodiesel fuel.     

Studies on the effect of temperature and time on the SS 304 surface for the properties degradation of the solar collector

The properties of emissivity (?) and absorptivity (α) of the surface of the material is an essential output for the solar collector. This paper highlights the work based on the RSM design expert, to study the effect of parameters’ temperature and time when the surface is exposed to sunlight and absorbing the properties of emissivity and absorptivity of the material SS 304. The temperature range of the SS 304 varied from 20°C to 356°C for various time intervals from 90 to 1100?h. From this experimental work, it is clearly seen that the emissivity rate increased when the surface is focused onto sunlight beyond the saturated level. The absorptivity of the surface of SS 304 increases till the optimum level and reaches the saturated level. As a result, after the optimum level, emissivity rate of the surface increases, and absorptivity of the surface decreases when it is focused onto sunlight.     

Optimisation of process parameters for electroless nickel plating on SS316L for refrigeration systems

Nowadays, refrigeration systems are important for industrial and domestic applications. The coefficient of performance of a vapour compression refrigeration system can be improved if a reduction in the work of compression can be achieved by a suitable technique for a specified heat removal rate. The present study investigates the effect of material coating of electroless nickel (EN) plating. The friction and wear experiments were performed using a four-ball machine tribo tester. Controlling the EN plating parameters plays an important role in the quality of coating. It depends on the wear scar rate of the coated material. So it is necessary to optimise the process parameters of EN plating. The experimental studies have been conducted under varying pressure, load and time on quality characteristics. In this paper, optimisation of process parameters using response surface methodology technique for EN plating was discussed.     

N,N,N-trimethyl chitosan nanoparticles as a vitamin carrier system

There is considerable interest in incorporating stabilized vitamins into biopolymeric nanoparticles, especially in the development of carriers and active systems for pharmaceutical and food applications. Amongst biopolymer, chitosan is highly desirable owing to its good biocompatibility, biodegradability and ability to be chemically modified. In this paper, nanoparticles from three kinds of water-soluble derivative chitosan (N,N,N-trimethyl chitosan, TMC) have successfully been synthesized by ionic gelation with tripolyphosphate (TPP) anions. Combinations of concentrations of TMC and TPP have resulted in nanoparticles with varying sizes for which the capability for loading with vitamins was investigated. Zeta potential measurement and particle size analysis demonstrated that the size of the nanoparticles was optimized (196 ± 8 nm) when the lowest TMC and TPP amounts were used, i.e., 0.86 mg mL⁻¹ and 0.114 mg mL⁻¹ respectively. As the TMC and/or the TPP concentrations increase, the resulting size of the nanoparticles increases considerably. Three different vitamins (B9, B12 and C) were tested as additives and the final system characterized in relation to size, morphology, spectroscopic and zeta potential properties. In general, the incorporation of vitamins increased all the TMC–TPP original nanoparticle sizes, reaching a maximum diameter of 534 ± 20 nm when loaded with vitamin C. The presence of vitamins also decreases the zeta potential, with one exception observed when using vitamin C. The preliminary results of this study suggested that all TMC/TPP nanoparticles can be successfully used as a stable medium to incorporate and transport vitamins, with potential applications in foodstuffs.     

Evaluation of incremental learning algorithms for HMM in the recognition of alphanumeric characters

We present an evaluation of incremental learning algorithms for the estimation of hidden Markov model (HMM) parameters. The main goal is to investigate incremental learning algorithms that can provide as good performances as traditional batch learning techniques, but incorporating the advantages of incremental learning for designing complex pattern recognition systems. Experiments on handwritten characters have shown that a proposed variant of the ensemble training algorithm, employing ensembles of HMMs, can lead to very promising performances. Furthermore, the use of a validation dataset demonstrated that it is possible to reach better performances than the ones presented by batch learning.     

Classical tone-shock conditioning induces zenk expression in the pigeon (Columba livia) hippocampus.

The hippocampus is involved in fear conditioning, although the molecular events underlying this function are still under investigation. The authors analyzed the expression of the Zenk proto-oncogene product within the pigeon (Columba livia) hippocampus after training with a classical aversive conditioning protocol using tone-shock associations. Control groups were trained with shock or tone alone or were only exposed to the experimental chamber and manipulated. Experimental pigeons showed significant increases of Zenk expression in the ventromedial region of the hippocampus, whereas both the experimental and shock groups had increased Zenk expression in the dorsal region. The expression of Zenk in specific neuronal populations within the pigeon hippocampus may be indicative of plasticity-associated aversive classical conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)