Assisted ultrasound applications for the production of safe foods

Ultrasound requires high power and longer treatment times to inactivate micro‐organisms when compared to ultrasound combined with other technologies. Previous reports have shown that the effectiveness of ultrasound as a decontamination technology can be increased by combining it with another treatment such as pressure, heat and antimicrobial solutions. Assisted ultrasound, the combination of ultrasound with another technology, is more energy efficient, and it has less impact on the food properties. In this review paper, the power ultrasound antimicrobial mechanisms of action, the antimicrobial effects of ultrasound in combination with other physical processes and antimicrobial solutions are comprehensively discussed. Furthermore, the present interest on using these technologies as alternative processing and decontamination methods is presented. Research outputs on the application of ultrasound combined with physical processes are showcased including applications of thermosonication, manosonication, manothermosonication and osmosonication. Antimicrobial efficacy, energy requirements and optimal operation conditions of the different assisted ultrasound technologies are critically discussed, and their impact on the food industry for future applications is presented. Overall, this review paper highlights the importance and recent developments of assisted ultrasound for enhancing food safety.     

Solvent interaction analysis as a proteomic approach to structure-based biomarker discovery and clinical diagnostics

Proteins have several measurable features in biological fluids that may change under pathological conditions. The current disease biomarker discovery is mostly based on protein concentration in the sample as the measurable feature. Changes in protein structures, such as post-translational modifications and in protein–partner interactions are known to accompany pathological processes. Changes in glycosylation profiles are well-established for many plasma proteins in various types of cancer and other diseases. The solvent interaction analysis method is based on protein partitioning in aqueous two-phase systems and is highly sensitive to changes in protein structure and protein–protein- and protein–partner interactions while independent of the protein concentration in the biological sample. It provides quantitative index: partition coefficient representing changes in protein structure and interactions with partners. The fundamentals of the method are presented with multiple examples of applications of the method to discover and monitor structural protein biomarkers as disease-specific diagnostic indicators.     

小蓬草水浸液对2种花卉种子萌发及幼苗生长的化感作用北大核心CSCD

为揭示入侵杂草与草本花卉之间的竞争关系,以入侵植物小蓬草为供体材料,常用的花卉波斯菊、观赏油菜为受体材料,研究了小蓬草根、叶水浸提液对受体植物种子萌发、幼苗生长、抗氧化酶活性(SOD、POD和CAT)以及丙二醛(MDA)含量的化感效应差异。结果表明,(1)小蓬草浸提液对受体植物的种子萌发均具有显著化感效应,基本表现为“低促高抑”的趋势,且波斯菊、观赏油菜的种子萌发率在根、叶浸提液浓度为25 g/L时最高,在浸提液浓度为100 g/L时最低。(2)小蓬草浸提液对受体植物幼苗上下胚轴生长具有“低促高抑”的浓度效应,且浓度越大抑制作用越显著。(3)在小蓬草根、叶浸提液处理下,观赏油菜的SOD和POD活性大多显著高于对照,波斯菊SOD和POD活性则大多显著低于对照;波斯菊、观赏油菜CAT活性整体呈先缓慢升高后降低的趋势。(4)波斯菊幼苗MDA含量随小蓬草根、叶浸提液浓度的增加均呈现逐渐升高的趋势,并大多高于对照水平,而观赏油菜幼苗MDA含量随着根浸提液浓度增加而逐渐升高,却随着叶浸提液浓度的增加而降低,但大多显著低于对照水平。研究发现,小蓬草浸提液对2种花卉种子萌发和幼苗生长均表现出“低促高抑”化感作用,且综合效应强弱表现为观赏油菜大于波斯菊,根浸提液处理大于叶浸提液。     

On the Accuracy of Numerical Solutions for Some Stereological Problems such as the Wicksell Corpuscle Problem

Two stereological problems—the estimation of sphere diameter distributions and the estimation of sheet thickness distributions from linear or plane sections—are considered. Their numerical solution consists in the solution of linear equation systems. To compare the quality of various methods theoretically, not only by experiments, the condition numbers of the matrices of the corresponding equation systems are determined.     

带饱和项的互惠交错扩散模型整体解的存在性和稳定性

应用能量估计方法和Gagliardo-Nirenberg型不等式证明了带饱和项的Shigesada-Kawasaki-Teramoto两种群互惠模型在齐次Neumann边值条件下整体解的存在唯一性和一致有界性.通过构造Lyapunov函数给出了该模型正平衡点全局渐近稳定的条件.     

Fluorescence Detection of Carbon-Centered Radicals in Aqueous Solution

A simple, highly sensitive method for the simultaneous determination of arrays of carbon-centered radicals in aqueous systems is described. Radicals are efficiently trapped by an amino-nitroxide to form stable products which are then reacted with fluorescamine to produce highly fluorescent adducts. The adducts are easily separated by reversed-phase high performance liquid chromatography. The detection limit for individual radical adducts (0.5 to 2nM) is two to three orders of magnitude lower than those of current methods employing electron paramagnetic resonance detection. Results on the photolysis of ketones and z-keto acids demonstrate the potential of this technique. This approach should be widely applicable to the study of radical processes in biological and chemical systems.     

The Influence of External Real and White Noise on the LOTKA-VOLTERRA Model

The behaviour of a marginally stable predator-prey system, the LOTKA -VOLTERRA model is analyzed under the influence of parameter fluctuations. The cases of white and real noise are studied separately. It is shown that for white noise no stationary solution exists, but even for time tending to infinity explosion occurs only with zero probability. In the case of real noise the class of noise processes that permit a stationary solution is characterized by their spectral density. It turns out that this class consists of all stationary processes that do not contain the eigenfrequencies of the LOTKA -VOLTERRA system. It is shown that for all other real noise processes a resonance phenomenon occurs and the solutions grow unboundedly.     

Association with HeLa cells of LPS mutants ofSalmonella typhimurium andSalmonella minnesota in relation to their physicochemical surface properties

Different LPS mutants ofSalmonella typhimurium andSalmonella minnesota have been investigated with respect to (1) their tendency to associate, with HeLa cell monolayers, and (2) their physicochemical surface properties. Aqueous biphasic partitioning, hydrophobic interaction chromatography, and ion exchange chromatography have been used to characterize the bacterial cell surface properties with respect to charge and hydrophobicity. Liability to hydrophobic interaction was defined either by the change of partition in a dextran-polyethylene-glycol (PEG) system by the addition of PEG-palmitate (P-PEG), or by the elution pattern from Octyl-Sepharose. Accordingly, charge was assessed by the effect of positively charged trimethylamino-PEG (TMA-PEG) on the partition, and by the elution from DEAE-Sephacel. Bacterial being negatively charged and liable to hydrophobic interaction had the highest tendency to associate with HeLa cells. In some cases the methods for surface analysis gave conflicting results on charge and/or liability to hydrophobic interaction of the same LPS mutant. Possible reasons for these differences and the role of bacterial cell surface structures contributing to physicochemical character are discussed.     

Towards a suitable antigen for diagnosis of Gnathostoma spinigerum infection.

, , , and 1992. Towards a suitable antigen for diagnosis of Gnathostoma spinigerum infection. International Journal for Parasitology 22: 1151–1156. Advanced third-stage larvae of G. spinigerum were obtained from two separate sources, namely from cysts in the livers of naturally infected eels (L3E) and from experimentally infected mice (L3M). Morphology of the L3E was studied microscopically. The larvae were homogenized in distilled water, 1% Triton X-100 or 1% sodium deoxycholate containing protease inhibitors. Protein compositions of the three crude extracts were compared, on the same weight basis, by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Coomassie brilliant blue staining while their antigenicities were studied by Western blot analysis using serum of a patient with parasitologically confirmed gnathostomiasis. Distilled water was found to be the best extraction solution in solubilizing proteins especially the diagnostic antigen, namely the 24,000 (24 kDa) mol. wt component from the larvae. The L3E and L3M contained relatively equal amounts of the 24 kDa antigen. This diagnostic component was anatomically located in the body fluid, oesophagus and intestine of the larva.     

On the stiffness of chitosan hydrochloride in acid-free aqueous solutions

Chitosan hydrochlorides (F_A=0.226, i.e. DA=22.6%) were randomly degraded by ultrasonication and characterized by viscosity measurements in aqueous acid-free solutions. It is shown that acid-free aqueous solutions of chitosan hydrochloride of variable ionic strengths (0.06 M≤μ≤0.3 M) are free of aggregation as evaluated by the values of the Huggins constants (0.31≤k≤0.63). These solutions were employed to study the solution properties of chitosan hydrochloride at different ionic strengths, which allowed the determination of its salt tolerance as well as its characteristic stiffness parameter. Following Smidsrod's approach chitosan hydrochloride gave a stiffness parameter B=0.06, in agreement with the value reported by Rinaudo et al. It is suggested that the higher values of B reported for chitosan in the literature may be attributed to aggregation.