Selective sorption of cesium using self-assembled monolayers on mesoporous supports

The synthesis of a novel nanocomposite sorbent material, copper ferrocyanide immobilized within a mesoporous ceramic matrix, and its use as a novel cesium sorbent material is reported in this paper. Complete removal of cesium was achieved in the presence of competing metal ions for solutions containing 2 ppm cesium under a variety conditions. Loading capacity of more than 1.35 mmol Cs per g of sorbent material has been achieved. The exceptionally fast binding kinetics and high loading capacity, resulting from the rigidly open pore structure and extremely high surface area of the sorbent materials, make them potentially very useful for the removal of cesium from nuclear wastes and contaminated groundwater.     

Recovery of surface bacteria from and surface sanitization of cantaloupes

Practical, effective methods that could be implemented in a food service establishment (restaurant or delicatessen) for the surface sanitization of cantaloupes were microbiologically evaluated. Cantaloupes (Cucumis melo L. var. reticulates) were immersed in an inoculum containing Salmonella enterica serovar Poona or Pantoea agglomerans at ca. 10(4) to 10(5) CFU/ml. An efficient method for the recovery of bacteria from the cantaloupe surface was developed and validated. The method consisted of washing the entire melon with Butterfield's buffer containing 1% Tween 80 in a plastic bag placed inside a plastic pail affixed to an orbital shaker. Levels of S. enterica Poona recovered by washing the entire melon were significantly higher than those recovered by the more common laboratory method of blending the rind. P. agglomerans can be used as a non-pathogenic proxy for S. enterica Poona. A three-compartment surface sanitization method consisting of washing with an antimicrobial soap solution, scrubbing with a brush in tap water, and immersion in 150 ppm of sodium hypochlorite reduced the initial level of recoverable viable bacteria by 99.8%. When examined separately, scrubbing with a vegetable brush in tap water, washing with soap, and dipping in chlorine were found to reduce the bacterial load by 70, 80, and 90%, respectively.     

Potentially pathogenic features of heterotrophic plate count bacteria isolated from treated and untreated drinking water

Heterotrophic plate counts (HPCs) are commonly used to assess the general microbiological quality of drinking water. Drinking water quality specifications worldwide recommend HPC limits from 100 to 500 cfu ml(-1). A number of recent studies revealed evidence that these bacteria may not be as harmless as generally accepted. It appears that immuno-compromised individuals are particularly at risk. This would include the very young and very old patients with diseases such as AIDS and patients on therapy for purposes such as organ transplantation and cancer treatment. In this study, 339 bacterial colonies were isolated at random from selected treated and untreated drinking water in South Africa using routine heterotrophic plate count tests. In a first step to screen for potentially pathogenic properties, 188 (55.5%) of the isolates showed alpha- or beta-haemolysis on human- and horse-blood agar media. Subsequent analysis of the haemolytic isolates for enzymatic properties associated with pathogenicity revealed the presence of chondroitinase in 5.3% of the isolates, coagulase in 16.0%, DNase in 60.6%, elastase in 33.0%, fibrinolysin in 53.7%, gelatinase in 62.2%, hyaluronidase in 21.3%, lecithinase in 47.9%, lipase in 54.8% and proteinase in 64.4%. Fluorescein and pyocyanin were not produced by any of the isolates. Among the haemolytic isolates, 77.7% were resistant to oxacillin 1 microg, 59.6% to penicillin G 2 units, 47.3% to penicillin G 10 units, 54.3% to ampicillin 10 microg and 43.1% to ampicillin 25 microg. Cell culture studies revealed that 96% of haemolytic isolates were cytotoxic to HEp-2 cells, and 98.9% of the 181 cytotoxic isolates adhered to HEp-2 or Caco-2 cells. HEp-2 cells were invaded by 43.6%, and Caco-2 cells by 49.7%, of the 181 cytotoxic isolates. The invasion index on HEp-2 cells ranged from 1.9 x 10(-1) to 8.9 x 10(-6), whereas the invasion index on Caco-2 cells varied between 7.7 x 10(-2) and 8.3 x 10(-6). The most commonly isolated genera with these potentially pathogenic features were Aeromonas, Acinetobacter, Aureobacterium, Bacillus, Chryseobacterium, Corynebacterium, Klebsiella, Moraxella, Pseudomonas, Staphylococcus, Tsukamurella and Vibrio. The results obtained in this study support earlier findings on potentially pathogenic features of bacteria detected by routine HPCs on drinking water. These findings are in agreement with some epidemiological studies, which indicated an association between HPCs in drinking water and the incidence of gastroenteritis in consumers. However, the extent of the health risk concerned needs to be defined in more detail for meaningful revision of quality guidelines for HPCs in drinking water.     

威海近海海葵附生异养菌的分离和多样性分析

对绿海葵的共附生异养菌群进行研究。从海葵的表面和匀浆液中分离到60株异养菌株,采用16SrRNA基因序列分析和部分生理生化试验,确定其中56株菌的种属情况。另外,对该类菌株所产胞外酶的情况以及与弧菌的拮抗情况进行测定。结果表明:这些可培养菌株的群落结构多样性较为丰富,其中的16株菌为假交替单胞菌属及其相关类群;其他菌株主要分布在其他19个属中。其中,17株菌可产胞外蛋白水解酶;20株菌可产胞外脂肪酶;菌株NQ8对一些弧菌具有较强的拮抗作用。     

Virulence and risk from drinking water of heterotrophic plate count bacteria in human population groups

Bacteria are natural inhabitants of all aqueous environments. The heterotrophic plate count is a means of assessing the concentration of these bacteria in foods, water, and water filtration systems. Methods vary, but are designed to enumerate bacteria that have evolved an environmental lifestyle. Most commonly, low nutrient, low ionic strength culture media are employed. The group of environmental bacteria enumerated depends on the media formulation and incubation conditions but are commonly known as heterotrophic plate count (HPC) bacteria; in Europe, this group is also referred to as autochthonous flora. While HPC inhabit an environmental niche, there has been concern that at some concentration they may be a human health risk. A review of the literature, including animal and human feeding studies, analysis of virulence factors, and outbreaks demonstrates that HPC bacteria as enumerated on HPC culture media have not been established as a human health threat at any concentration in drinking water or foods.     

利用响应面法优化海洋细菌YDX-1产纤维素酶的发酵条件

采用响应面法对海洋细菌YDX-1产纤维素酶的发酵条件进行了优化。首先用Plackett-Burman法从8个因子中筛选出3个主要影响YDX-1产酶的因素,然后进行最陡爬坡实验逼近最佳响应面区域,最后通过Box-Behnken响应面设计实验得到最适条件为温度31℃、羧甲基纤维素钠(CMC-Na)41g/L、(NH4)2SO44.7g/L。在最适条件下测得的酶活为273.20U/mL,较优化前的150.13U/mL提高了81.97%。     

响应面法优化厌氧细菌产纤维素酶发酵培养基

通过单因素试验确定了厌氧纤维素降解细菌—溶纤维丁酸弧菌WHQ产纤维素酶的最佳培养条件,结果表明,最适产酶条件为培养时间48h,接种量10％,初始pH值8.5,温度37℃.在此基础上,应用响应面法优化该菌株产纤维素酶培养基.在初期研究中,葡萄糖和尿素确定为最佳的碳氮源,利用Plackett-Burman设计从10种培养基成分中筛选出对WHQ产内切纤维素酶有重要性的因素,结果表明葡萄糖、NaHCO,和MgSO4·7H2O对WHQ产内切纤维素酶有重要影响,利用Box-Behnken设计研究这3种因素对WHQ产内切纤维素酶的综合效应,结果表明3种因素的最佳值为MgSO4·7H2O 0.14g/L、葡萄糖14.3g/L、NaHCO3 6.92g/L,此时的内切酶酶活力最大值为206.548μg/(mL.min),与实验值相接近199.324μg/(mL·min),比未优化前的内切纤维素酶活力71.254μg/(mL·min)提高179％.     

Experimental simulation of solar drying of garlic using an adsorbent energy storage bed

Solar drying of garlic with energy storage in silica gel is experimentally simulated in a closed system in which the air is continuously circulated between food and adsorbent. Kinetics of the drying process are studied and equilibrium data are predicted by a mathematical model developed from the experimental results. By comparing the end points of drying with equilibrium values the length of the drying process can be established.From sorption data, a garlic surface area of 63–188 m² g^?1 and a heat of adsorption in the first layer of 2548–2691 kJ kg^?1 have been calculated. A value of 746 kJ kg^?1 has been deduced for the activation energy for water removal.     

Effects of surface ageing on wettability, surface chemistry, and adhesion of wood

The effects of ageing on the surface chemistry, wettability and the surface free energy were determined according to the acid base theory using contact angle measurements and x-ray photoelectron spectroscopy. Time is a significant variable affecting wettability and adhesion. All measured surface parameters of the wood surface were storage time dependent. It could be demonstrated that the effect of ageing on the adhesion of a coating on the wood surface depends not only on the properties of the wood surface, but also on the chemical nature of the coating. Therefore, measurements on wettability without considering the time dependence of surface energy and, above all, its components, are not sufficient to assess effects of ageing on adhesion.     

Development of quantitative analysis for the micro-relief of the skin surface using a video microscope and its application to examination of skin surface texture

We developed a new analyzing method for characterizing a skin surface morphology image obtained easily by a video microscope. For the numerical analysis of various characteristics of the skin surface morphology, three parameters were invented; 'the width of the skin furrows,'the fineness of the skin ridges,' and 'the size of the skin pores.' The width of the skin furrows was calculated as mean width of the skin furrows. The fineness of the skin ridges was calculated as number of the skin ridges. The size of the skin pores was calculated as total area of skin pores. The analyzed parameters were compared with the clinical scores evaluated by trained experts, resulting in a high correlation (r = 0.54–0.72). Upon the age related changes in the parameters described above, the number of the skin ridges decreased at around the age of 20, and the size of the skin pores became large with aging during the teens through 40's. In the analysis of seasonal changes, the ridge parameter was high in summer, and the furrow parameter was high in winter. Upon the relationship between the images (the skin surface patterns) and the skin physiological parameters, the skin with a low barrier function (high TEWL) or that with high sebum content gave a low density of the skin ridges. From these results it seems that the image analysis of skin surface morphology using a video microscope is quite useful for an easy and simple evaluation of skin condition.     

Study of tensile properties of plain-woven fabrics in all-directional using energy method,Part I: theoretical study

Abstract

In the first part of this series, a new mechanical parameter, that is, “Comprehensive Tensile Modulus (CTM)” is introduced and modeled to show the tensile behavior of plain-woven fabrics in the initial linear elastic region of the force-elongation curve subjected to tensile load and extended it simultaneously in all directions. Considering the initial load-extension behavior of fabrics, a mathematical-mechanical model is presented to predict the CTM of fabrics in the initial linear elastic region using Castigliano’s theorem. Based on the generated model, the initial sample length, dimension of the load imposed region, the geometrical shape created in the plain-woven fabric sample during tensile, the structural specification of these fabrics such as yarns sett, yarns crimp in fabric and mechanical properties of yarns such as bending rigidity in both warp and weft yarns affect in the comprehensive tensile modulus of fabric. In order to verify the conformity and accuracy of the model, a preliminary test was conducted on the prepared samples based on a novel tensile test method developed to measure load-extension curve of the fabric samples under the proposed loading condition. A reasonable agreement was found between theoretical and experimental results.     

Experimental and theoretical analysis of air-inflated circular woven fabric deformation

In this study, a bulge tester is designed and constructed in order to simulate air-inflated fabric deformations. The shadow moiré method is used to analyze and reconstruct the 3-D profile of the deformed fabric. To verify the results of the shadow moiré method, front view photography is performed. Theoretical modeling of fabric deformation is carried out through uniform pressure and energy methods. The experimental results showed that the fabric deformation decreases as the angular distance from warp and weft directions increases. The fabric deformation increases nonlinearly with the air pressure in which the fabric with a higher density exhibits a slightly lower deformation. Theoretical results showed good agreement with the experimental results.     

Experimental investigation and theoretical modelling of absolute convective drying of starch

Starch is a granular, hygroscopic, capillary-porous material with an intricate structure. It is known that drying starch till 0% moisture is a physical treatment that modifies starch properties. However, depending upon the heat and mass transfer mechanisms prevalent in the drying system, starch properties are modified in a unique manner. Therefore, the drying operation itself needs to be thoroughly understood. Potato starch was treated in an oven at three high-temperature levels (110, 130 and 140 °C) and for three sample thicknesses (2.8, 5.6 and 11.2 mm). It was observed that drying of starch with moisture content in the hygroscopic range occurred only in the 2nd falling rate period. Two existing theoretical, drying models, one based upon the Krischer Theory and the other based upon the Percolation Approach, were considered apt for modelling the oven drying. Both models describe the experimentally measured moisture profiles well. During drying, transition from one water sub-population to another was smooth. The effective diffusion coefficient decreased with moisture content and increased with temperature, but did not follow Arrhenius’ Law above 130 °C.     

Enumeration of total heterotrophic and psychrotrophic bacteria using different types of agar to evaluate the microbial quality of blue mussels (Mytilus edulis) and sea scallops (Placopecten magellanicus)

Microbial quality of Fortune Harbor, NL, cultured blue mussels stored at three temperatures (−12, 2 and 9 °C) for 10 days was evaluated using aerobic plate count (APC) and psychrotrophic plate count (PPC) on plate count agar (PCA) and marine agar (MA). The relationship between bacterial counts in Fortune Harbor mussels on PCA and MA was established using linear regression analysis. The accuracy of selected linear models to predict bacterial count on MA using bacterial counts on PCA of wild and cultured mussels and scallops, stored at 2 °C, was examined. The shelf life of stored mussels and scallops was estimated based on bacterial counts, agar type and storage temperature. Results showed that bacterial counts (APC and PPC) in Fortune Harbor mussels on MA were significantly (p < 0.05) higher than their corresponding counts on PCA agar at all storage temperatures. A strong correlation (r > 0.7, p < 0.01) was observed between bacterial counts in mussels stored at 2 and 9 °C on PCA and MA. The accuracy of the linear models to predict bacterial counts of bivalves on MA using the counts on PCA ranged from 60% to 93%. Both temperature and agar type influenced microbial shelf life estimation while the type of bacteria (APC or PPC) had a lesser effect. Results of this study strongly suggest the use of MA to evaluate the general microbial quality of bivalves instead of PCA or PCA + 1% NaCl.     

Survival of lactic acid bacteria in the human stomach and adhesion to intestinal cells

The survival of four strains of lactic acid bacteria in human gastric juice, in vivo and in vitro, and in buffered saline, pH 1 to 5, has been investigated. The strains studied include two Lactobacillus acidophilus strains, Lactobacillus bulgaricus, and Streptococcus thermophilus. In addition, the adhesion of these strains to freshly collected human and pig small intestinal cells and to pig large intestinal cells has been studied and the effect of milk on both survival and adhesion tested. As a result of these investigations, an in vitro test system for screening potential cultures for use as human dietary adjuncts can be developed. The ability to survive in gastric juice and to adhere varied significantly for the strains tested; L. acidophilus ADH survived and adhered better than the others while S. thermophilus survived and adhered poorly. For all strains, both survival and adhesion was enhanced by milk. As all strains adhered to some extent to both human and pig intestinal cells, the adhesion mechanism is probably a nonspecific attachment as opposed to other reported specific Lactobacillus adhesion to gastric tissue. From the survival and adhesion data it seems feasible to obtain elevated levels of viable Lactobacillus sp. in human intestine by careful selection of the bacterial strains ingested. Furthermore, the in vitro methods used here should be valuable to screen potential strains. The data presented here can then be correlated with human in vivo studies monitoring the beneficial effect of ingestion of these Lactobacillus.     

禽蛋表面细菌污染及影响因素的调查分析

目的检测养殖场的禽蛋受细菌污染的情况,调查分析禽蛋表面细菌污染的主要影响因素。方法根据GB 4789.2-2010食品安全国家标准食品微生物学检验菌落总数测定对饲养场的蛋壳表面、饲料、垫草中的细菌菌落总数进行测定,采用沉降法测定饲养场空气中的细菌数,并进行统计分析。结果饲养场鸡蛋和鸭蛋表面的细菌菌落总数分别达到4~6和6~7个数量级,且饲养场的空气、饲料以及垫草中的细菌数越多,从蛋壳表面检测出来的细菌数也越多。结论养殖场的禽蛋均受到不同程度的细菌污染,且饲养场的空气、饲料、垫草是造成禽蛋表面细菌污染的主要原因,禽蛋生产过程中卫生管理非常重要。     

响应面法优化乳酸菌发酵胡萝卜原浆工艺及香气成分变化分析

以胡萝卜为原材料,以富含乳酸菌的发酵剂为菌种,利用响应面法对胡萝卜原浆的发酵工艺条件(发酵时间、发酵剂加量、发酵温度)进行优化。结果表明:经优化后,胡萝卜原浆最佳发酵工艺条件为发酵27 h、发酵剂加量0.16 g、发酵温度40℃,在该条件下测得胡萝卜发酵浆的总酸为5.5335 g/L、p H为3.99、总糖为0.1287 g/L、还原糖为0.1198 g/L、乳酸菌菌落总数为8.72 lg(cfu/m L),与预测值相接近。胡萝卜原液与发酵液分别检测出34、33种香气成分,其在发酵过程中变化明显,发酵液掩盖了胡萝卜原有的药腥味,因此可以作为一种新型健康的益生菌制品得到推广。      

Experimental and theoretical study of LDPE: Evaluation of different food simulants and temperatures

The mass transfer process of additives from plastic packaging to food is of great importance and interest because of the possible harmful effects on the human health. In this work the effect of different food simulants (EtOH 10–50%) and temperatures (28–60 °C) on the specific migration of Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (I-1076) from LDPE films is experimentally and theoretically studied, considering also the antioxidant stability in the food simulants studied at different temperatures.On the other hand, a phenomenological model based on a resistances-in-series which was resolved through the Regula Falsi algorithm according to a routine that considers the income of the structural parameters of the system and experimental conditions in which migration testing was performed. Diffusion coefficients of I-1076 in LDPE were ranged between 8.0E10–14 and 1.2E10–12 (m² s^{− 1}) for temperatures of 28 to 60 °C, respectively. The coupled effect of mass transfer and thermodynamical aspects was analyzed through the parameter Bi/K_P/FS proposed in this work, estimated in order to identify the combined contribution of the transport rate and the availability of the migrant compound in the food phase.     

Experimental and theoretical study of thermodynamics and transport properties of multilayer polymeric food packaging

The specific migration of Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (I-1076) from three-layer low-density polyethylene plastic films into a fatty food simulant was studied. The film samples, having a symmetrical structure with a contaminated core layer and virgin outer layers, were developed with a known amount of a selected migrant in the inner layer. A phenomenological model based on a resistances-in-series was resolved through the regula falsi algorithm according to a routine that considers the income of the structural parameters of the system and experimental conditions in which migration testing was performed. The model’s accuracy in predicting migration was demonstrated successfully by comparing simulated results to experimental data. The computer program, developed as a total solution package for migration problems, can be applied not only to multilayer structures made with the same type of plastics but also to structures with different plastics.