一种基于深度森林的恶意代码分类方法

针对当前恶意代码静态分析方法精度不足的问题，将恶意代码映射为无压缩的灰度图像，然后根据图像变换方法将图像变换为恒定大小的图像，使用方向梯度直方图提取图像的特征，最后提出一种基于深度森林的恶意代码分类方法.实验中选择不同家族的多个恶意代码样本进行分类，验证了该方法的有效性，并且实验结果优于近期提出的SPAM-GIST方法.     

The use of seed texture features for discriminating different cultivars of stored apples

The aim of this study was to identify the textural features of apple seeds with the highest discriminatory power for distinguishing the seeds of different apple cultivars with the use of discriminative classifiers. The seeds of apple cvs. Gala, Jonagold and Idared were scanned with the use of a flatbed scanner, and the acquired images were processed to calculate textural features from color channels: L, a, b, R, G, B, Y, U, V, H, S, I, X, Y and Z. The selected textures were used to develop discriminative models and distinguish the seeds of the examined apple cultivars. The analyses were performed for color spaces and color channels. The seeds of apple cvs. Gala and Idared were discriminated with 100% accuracy in models based on the textures from Lab and YUV color spaces and color channel L for the Naive Bayes, Multilayer Perceptron and Multi Class classifiers. The discriminatory accuracies of the seeds of all analyzed apple cultivars (Gala, Idared and Jonagold) ranged from 72% to 85%. The discriminatory accuracy of the textures selected from Lab color space for the Naive Bayes classifier reached 85%. The seeds of apple cvs. Gala and Jonagold were discriminated with 78–90% accuracy, and the discriminatory accuracy of the textures from Lab color space and color channel b for the Naive Bayes classifier reached 90%. The seeds of apple cvs. Idared and Jonagold were distinguished with 80–94% accuracy. The models based on textures from Lab color space and color channel b for the Naive Bayes classifier were characterized by 94% discriminatory accuracy. The study demonstrated that textural features are useful for discriminating the seeds of different apple cultivars.     

Detecting Cysteine in Bioimaging with a Near-Infrared Probe Based on a Novel Fluorescence Quenching Mechanism

Near-infrared (NIR) fluorescent probes are very significant for detecting cysteine in biological systems. Herein, we report a highly selective and sensitive NIR turn-on fluorescent probe (BDP-NIR) based on BODIPY with large Stokes shift (105 nm) for detecting Cys. We clarified the sensing mechanism based on the different thiol-induced S_NAr substitution/rearrangement reaction of the probe with cysteine and homocysteine/glutathione, which leads to the corresponding amino- and thiol-BODIPY dyes with distinct photophysical properties. Moreover, a novel mechanism of fluorescence quenching was demonstrated by density functional theory calculation. The reason for the fluorescence quenching of the probe might be intersystem crossing (from singlet to triplet excited state). Moreover, BDP-NIR had a high linear dynamic range of 0–500 μM, which was promising for detecting cysteine quantificationally. Significantly, BDP-NIR was capable of sensing endogenous cysteine in living cells and in vivo.     

Effects of red beet extracts on protein and lipid oxidation,colour, microbial,sensory properties and storage stability of Turkish pastırma

Lipid oxidation and discoloration are two important problems in the storage of pastırma, a meat product. In this research, the usability of lyophilized red beet water extract (LRBWE) in cemen paste and its effects on the pastırma quality (especially colour, protein and lipid oxidation, microbial and sensory properties) were investigated during storage. Two trials were conducted; in trial 1, LRBWE was obtained, its various properties were designated and effects on the cemen paste of these extracts (0.0%, 0.4%, 0.6%, 0.8% 1.0% and 1.2%) were determined. In trial 2, pastırma with cemen paste containing 0.8%, 1.0% and 1.2% LRBWE were produced and stored at 4 ± 1 °C for 150 days. The LRBWE did not influence protein oxidation of pastırma, whereas increasing LRBWE level led to a decrease in lipid oxidation (P < 0.01), and an increase in redness (a1) value (P < 0.01) and sensory properties (P < 0.01) of sliced pastırma compared with control pastırma. These results revealed that the addition of 1.0% or 1.2% LRBWE to cemen paste was effective to improve the colour stability, lipid oxidation, microbial and sensory quality of pastırma during storage.     

Reinforcement and toughening mechanisms in polymer nanocomposites – Carbon nanotubes and aluminum oxide

The addition of nanoparticles has been reported as an option to increase the fracture toughness of thermosetting polymers without compromising the stiffness. In this paper, alumina or carbon nanotubes (CNTs), in three different concentrations, were dispersed in an epoxy resin. Mechanical properties were measured through tensile test and the results indicate increases for all nanocomposites, with a maximum for the addition of 0.5% of CNTs (17% in elastic modulus and 22% in ultimate stress). Using TEM images, it was possible to identify the nanostructures and mechanisms that lead to improved stiffness. Fracture toughness tests and SEM images showed that cavitation – shear yielding (for epoxy/alumina nanocomposites) and crack bridging – pull-out (for epoxy/CNTs nanocomposites) are the predominant mechanisms.     

Simulation and experimental study of the NOx reduction by unburned H2 in TWC for a hydrogen engine

The unburned H₂ can be used to reduce NO emission in conventional TWC (three-way catalyst) for a hydrogen internal combustion engine when it works at equivalence ratio marginally higher than the stoichiometric ratio. To explore the effects and feasibility of this reaction, a Perfectly Stirred Reactor simulation model of TWC has been built with simplified mechanisms. Experiments on a 2.3 L turbocharged hydrogen engine are used to verify the conclusion. It shows that rising initial temperature accelerates the reduction of NO and the maximum reaction rate occurs at 400 °C temperature. The conversion efficiency of NO remains approximately 0 when temperatures below 300 °C. The efficiency reaches a peak value of approximately 98% with 400 °C and declines gradually. The unburned H₂ to NO mixing ratio greater than 1.5 in TWC guarantees 100% NO conversion efficiency. The experiments indicate that the NOx concentration decreases from 2056 ppm to 41 ppm at the stoichiometric ratio after the treatment of TWC and NOx reaches 0 ppm with a rich ratio. Results also demonstrate that the suitable reaction temperatures for TWC locate in the range of 400 °C–500 °C. Therefore, if the temperature and the mixing ratio are appropriate, it can achieve zero emissions with NOx reduction by unburned H₂ in conventional TWC for a hydrogen engine.     

Evaluating hydrogen detection performance of an electrospun CuZnFe2O4 nanofiber sensor

CuZnFe₂O₄ nanoparticles (<50 nm) are successfully synthesized and incorporated in polyvinyl alcohol (PVA) to fabricate nanofibers via electrospinning technique followed by calcination process under various temperatures. Scanning electron microscopy (SEM) is used to observe the morphological characteristics of both nanoparticles and nanofibers. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermo-gravimetric (TG) analyses along with energy dispersive X-ray spectrometer (EDX) analysis are conducted to evaluate structure and composition of the nanofibers, respectively. The results exhibit that the calcination temperature is substantially effective on nanofiber morphology and sensing performance in the context of forming grains (beads) on the nanofibers. The highest response and recovery performance values (response and recovery time of about 6.5 s) are obtained at the calcination temperature of 500 °C and sensor working temperature of 250 °C at 500 ppm of H2 gas concentration which also corresponds to 30% increment in detection performance compared to 300 °C-calcined nanofiber sensor. The sensor selectivity against various gases is also analyzed to compare the detection performance in air.     

Facile one pot sonochemical synthesis of CoFe2O4/MWCNTs hybrids with well-dispersed MWCNTs for asymmetric hybrid supercapacitor applications

In this study, a facile sonochemical strategy is used for the fabrication of CoFe₂O₄/MWCNTs hybrids as an electrode material for supercapacitor applications. FE-SEM image demonstrates the uniformly well-distributed MWCNTs as well as porous structures in the prepared CoFe₂O₄/MWCNTs hybrids, suggesting 3D network formation of conductive pathway, which can enhance the charge and mass transport properties between the electrodes and electrolytes during the faradic redox reactions. The as-fabricated CoFe₂O₄/MWCNTs hybrids with the MWCNTs concentration of 15 mg (CFC15) delivers maximum specific capacitance of 390 F g⁻¹ at a current density of 1 mA cm⁻², excellent rate capability (275 F g⁻¹ at 10 mA cm⁻²), and outstanding cycling stability (86.9% capacitance retention after 2000 cycles at 3 mA cm⁻²). Furthermore, the electrochemical performance of the CFC15 is superior to those of pure CoFe₂O₄ and other CoFe₂O₄/MWCNTs hybrids (CFC5, CFC10 and CFC20), indicating well-dispersion MWCNTs and uniform porous structures. Also, as-fabricated asymmetric supercapacitor device using the CoFe₂O₄/MWCNTs hybrids as the positive electrode and activated carbon as the negative electrode materials shows the outstanding supercapacitive performance (high specific capacitance, superior cycling stability and good rate capability) for energy storage devices. It delivers a capacitance value of 81 F g⁻¹ at 3 mA cm⁻², ca. 92% retention of its initial capacitance value after 2000 charge-discharge cycles and excellent energy density (26.67 W h kg⁻¹) at high power density (~319 W kg⁻¹).     

One-step synthesis of CuCo2O4-Sm0.2Ce0.8O1.9 nanofibers as high performance composite cathodes of intermediate-temperature solid oxide fuel cells

One-dimensional nanostructured CuCo₂O₄-Sm_0.2Ce_0.8O_1.9 (SDC) nanofibers are prepared by the electrospinning method and one step sintering as a cathode with low polarization resistance for intermediate temperature solid oxide fuel cells (IT-SOFC). The CuCo₂O₄-SDC nanofibers cathodes form a porous network structure and have large triple-phase boundaries. Correspondingly, the electrochemical performance of the CuCo₂O₄-SDC nanofibers composite cathodes shows significantly improve, achieving the polarization resistance of 0.061 Ω cm² and the maximum power densities of 976 mW·cm⁻² at 750 °C. Thus, these results suggest that CuCo₂O₄-SDC nanofiber could be a highly active cathode material for IT-SOFCs.     

Biochemical changes in groundnut pods due to infestation of bruchid Caryedon serratus (Olivier) under stored conditions

A study on the “Biochemical changes in groundnut pods due to infestation of bruchid, Caryedon serratus (Olivier) under stored conditions” was conducted at Department of Entomology, College of Agriculture, SVPUA&T, Meerut during August 2018 to February 2019. Results of the study showed that there was significant increase in weight loss of the groundnut pods (test varieties) with the increase in storage period i.e. 30, 90, and 150 DAS (days after storage). This significant increase in weight loss was due to infestation of groundnut bruchid. In addition to the weight loss, distinct differences in the biochemical components such as sugars, proteins, tannins, phenols were found in between infested and uninfested groundnut pods. A significant reduction in sugars, tannins, phenol whereas increase in protein content was noticed with the increase in the storage period i.e. 30, 90 and 150 DAS. Correlation studies relating weight loss and biochemical components from different groundnut varieties (resistant and susceptible) due to bruchid infestation were also worked out in the study. Pod sugar and pod protein content showed significant positive correlation with weight loss (positive effect on the development of the bruchid). While, pod tannins and pod phenols content showed significant negative correlation with weight loss (exerted a negative effect on the development of the bruchid).