The Evaluation of Mechanical,Thermal, Optical and Microstructural Properties of Edible Films with Solid Lipid Nanoparticles-Xanthan Gum Stored at Different Temperatures and Relative Humidities

Solid lipid nanoparticles (SLN) were obtained using the hot homogenization method and incorporated into a xanthan gum matrix (XG) to prepare edible films. The effects of SLN content (60, 65, 70, and 75 g/L) on the mechanical, color, thermal and microstructural properties, and water vapor permeability (WVP) were studied. The SLN film-forming systems remained stable for 7 weeks. Particle size was in the range of 222–257 nm. The mechanical properties of the films improved significantly when the SLN were introduced into the polymeric network to provide greater strength and flexibility with elongation at breaking of 2–9 %, affected by temperature (4–25 °C), SLN concentration (60–75 g/L), and relative humidity (60–90 %). WVP was lower when edible films based on XG were incorporated with SLN at values of 0.50–0.70 g m-2 h-1 kPa^?1. The distribution of the SLN in the XG matrix was observed under scanning electron microscopy and showed changes in the arrangement as a function of SLN concentration. This explains the positive effect on the properties of the film of SLN-XG at 60 and 65 g/L. Total color difference (ΔE) increased with SLN content at values of 3.5–14. Thermal analysis showed that higher SLN content increased the melting temperature, while the plasticizer reduced it.     

Toxicity of silver, zinc, copper, and nickel to the copepod Acartia tonsa exposed via a phytoplankton diet

Toxicity tests were conducted with the marine copepod Acartia tonsa to assess the effects of dietary metal exposure. The diatom Thalassiosira pseudonana was cultured with Ag, Zn, Cu, or Ni and used as diets for adult A. tonsa over a 7-d exposure, and copepod survival and reproduction were measured throughout the exposure period. For all metals, reproduction was the most sensitive endpoint, with 20% effect concentrations (EC(20)s) corresponding to exposures of T. pseudonana to 0.64, 0.3, 1.2, and 2.4 microg/L for Ag, Zn, Cu, and Ni, respectively. The corresponding metal concentrations in the algae added to copepod test solutions (EC(20)s) were 5.44, 0.55, 22.3, and 15.3 microg/g for Ag, Zn, Cu, and Ni, respectively. None of the applied metal concentrations influenced algal growth. The results of this study have potential implications for water quality criteria considering that the estimated EC(20)s fall below the current criteria of 3, 86, 3, and 8.3 microg/L for Ag, Zn, Cu, and Ni, respectively.     

重金属Cd与Cu在克氏原螯虾体内富集与释放规律

研究克氏原螯虾分别在Cd2+质量浓度为0、0.05、0.10 mg/L和Cu2+质量浓度为0、0.5、1.0 mg/L的单一水环境中暴露时,肝胰腺、鳃和肌肉对Cd和Cu的生物富集和释放特性。通过非线性拟合得到克氏原螯虾对Cd和Cu的生物富集动力学参数：富集速率常数k1、排出速率常数k2、生物富集系数（bioconcentration factors,BCF）和生物半衰期（T1/2）,并得出理论富集平衡状态时生物体内Cd和Cu富集量（ρAmax）。结果表明：克氏原螯虾的肝胰腺和鳃对水体中Cd2+和Cu2+都有很强的富集特性,且富集量与富集时间、水体中Cd2+和Cu2+的质量浓度成正相关;肌肉组织中富集规律则不明显。同种重金属在不同组织中的富集量不同,即重金属富集具有组织选择性：在分别含Cd2+和Cu2+的水体中暴露实验9 d后,3 种组织对Cd的富集量顺序为鳃＞肝胰腺＞肌肉;对Cu的富集量顺序为肝胰腺＞鳃＞肌肉。克氏原螯虾对Cu和Cd的富集代谢都较缓慢,暴露9 d仍未达到稳定。克氏原螯虾体内Cd和Cu的BCF范围分别约为2～207、3～226;T1/2分别约为3～29、7～36 d;在理论平衡状态下,鳃、肝胰腺和肌肉中Cu和Cd的ρAmax随着环境中Cu2+和Cd2+质量浓度的增大而增大,且呈正相关。     

Intracellular silver accumulation in Chlamydomonas reinhardtii upon exposure to carbonate coated silver nanoparticles and silver nitrate

The intracellular silver accumulation ({Ag}(in)) upon exposure to carbonate coated silver nanoparticles (AgNP, 0.5-10 μM, average diameter 29 nm) and silver nitrate (20-500 nM) was examined in the wild type and in the cell wall free mutant of the green alga Chlamydomonas reinhardtii at pH 7.5. The {Ag}(in) was measured over time up to 1 h after a wash procedure to remove silver ions (Ag(+)) and AgNP from the algal cell surface. The {Ag}(in) increased with increasing exposure time and with increasing AgNP and AgNO(3) concentrations in the exposure media, reaching steady-state concentrations between 10(-5) and 10(-3) mol L(cell)(-1). According to estimated kinetic parameters, high Ag(+) bioconcentration factors were calculated (>10(3) L L(cell)(-1)). Higher accumulation rate constants were assessed in the cell wall free mutant, indicating a protective role of the cell wall in limiting Ag(+) uptake. The bioavailability of AgNP was calculated to be low in both strains relative to Ag(+), suggesting that AgNP internalization across the cell membrane was limited.     

Evaluation of the Genotoxicity of Chitosan Nanoparticles for Use in Food Packaging Films

Abstract: The use of nanoparticles in food packaging has been proposed on the basis that it could improve protection of foods by, for example, reducing permeation of gases, minimizing odor loss, and increasing mechanical strength and thermal stability. Consequently, the impacts of such nanoparticles on organisms and on the environment need to be investigated to ensure their safe use. In an earlier study, Moura and others (2008a) described the effect of addition of chitosan (CS) and poly(methacrylic acid) (PMAA) nanoparticles on the mechanical properties, water vapor, and oxygen permeability of hydroxypropyl methylcellulose films used in food packaging. Here, the genotoxicity of different polymeric CS/PMAA nanoparticles (size 60, 82, and 111 nm) was evaluated at different concentration levels, using the Allium cepa chromosome damage test as well as cytogenetic tests employing human lymphocyte cultures. Test substrates were exposed to solutions containing nanoparticles at polymer mass concentrations of 1.8, 18, and 180 mg/L. Results showed no evidence of DNA damage caused by the nanoparticles (no significant numerical or structural changes were observed), however the 82 and 111 nm nanoparticles reduced mitotic index values at the highest concentration tested (180 mg/L), indicating that the nanoparticles were toxic to the cells used at this concentration. In the case of the 60 nm CS/PMAA nanoparticles, no significant changes in the mitotic index were observed at the concentration levels tested, indicating that these particles were not toxic. The techniques used show promising potential for application in tests of nanoparticle safety envisaging the future use of these materials in food packaging.     

First-milking colostrum mineral concentrations and yields: Comparison to second milking and associations with serum mineral concentrations,parity, and yield in multiparous Jersey cows

This observational study described first-milking colostrum mineral concentrations and total yields, and evaluated its associations with cow serum mineral concentrations, parity, and first postpartum milking yield in 100 multiparous Jersey cows from a single herd fed a negative dietary cation-anion difference diet prepartum. Additionally, first- and second-milking colostrum mineral concentrations and total yields were compared in a subset of 65 cows. Serum minerals (Ca, P, Mg, Na, K, Zn, Fe, Cu) were assessed before first milking. Cows were milked at 9 h and 4 min ± 3 h and 32 min and at 21 h and 11 min ± 3 h and 43 min postpartum (± standard deviation); yields were recorded and samples collected for mineral concentrations assessment (Ca, P, Mg, Na, K, Zn, Fe, Cu). Linear regression was used to evaluate the associations between first-milking colostrum mineral concentrations and total yields and cows' serum mineral concentrations, parity, first-milking colostrum yield, and calving-to-milking interval. The most abundant minerals in first-milking colostrum were (least squares mean ± standard error of the mean) Ca (55.71 ± 13.52 mmol/L; 8.75 ± 5.74 g) and P (41.91 ± 13.01 mmol/L; 5.26 ± 3.72 g), followed by Na (39.65 ± 13.23 mmol/L; 3.08 ± 1.77 g), K (36.47 ± 7.57 mmol/L; 5.79 ± 4.20 g), Mg (13.43 ± 3.09 mmol/L; 1.25 ± 0.78 g), Zn (272.12 ± 113.34 μmol/L; 71.98 ± 55.34 mg), Fe (12.51 ± 3.79 μmol/L; 2.56 ± 1.55 mg), and Cu (3.34 ± 1.22 μmol/L; 0.77 ± 0.56 mg). Higher concentrations of Ca, Mg, Na, Zn, Fe, and Cu, and total yields of Mg, Zn, Fe, and Cu were observed at first- compared with second-milking colostrum. Serum and first-milking colostrum Cu concentrations were positively associated, but no significant associations were observed between other minerals' serum and first-milking colostrum concentrations or total yields. Parity was associated with first-milking colostrum Ca, P, K, and Fe concentrations and yields; younger multiparous cows had higher concentrations and total yields of these minerals. Linear (Fe), quadratic (P, Na, and K), and cubic (Mg, Zn, and Cu) associations were observed between first-milking colostrum mineral concentrations and yield. In all cases, mineral total yields were linearly associated with first-milking colostrum yield. In conclusion, variation in first-milking colostrum mineral concentrations and total yields across cows could be partially explained by cow parity and colostrum yield. Further research including primiparous and cows under different management settings is needed to expand the knowledge and understanding of colostrum mineral concentrations and total yields in dairy cows.     

Effects of copper nanoparticles exposure in the mussel Mytilus galloprovincialis

CuO NPs are widely used in various industrial and commercial applications. However, little is known about their potential toxicity or fate in the environment. In this study the effects of copper nanoparticles were investigated in the gills of mussels Mytilus galloprovincialis, comparative to Cu(2+). Mussels were exposed to 10 μg Cu·L(-1) of CuO NPs and Cu(2+) for 15 days, and biomarkers of oxidative stress, metal exposure and neurotoxicity evaluated. Results show that mussels accumulated copper in gills and responded differently to CuO NPs and Cu(2+), suggesting distinct modes of action. CuO NPs induced oxidative stress in mussels by overwhelming gills antioxidant defense system, while for Cu(2+) enzymatic activities remained unchanged or increased. CuO NPs and Cu(2+) originated lipid peroxidation in mussels despite different antioxidant efficiency. Moreover, an induction of MT was detected throughout the exposure in mussels exposed to nano and ionic Cu, more evident in CuO NPs exposure. Neurotoxic effects reflected as AChE inhibition were only detected at the end of the exposure period for both forms of copper. In overall, these findings show that filter-feeding organisms are significant targets for nanoparticle exposure and need to be included when evaluating the overall toxicological impact of nanoparticles in the aquatic environment.     

Inhibition and inactivation of Listeria monocytogenes and Escherichia coli O157:H7 colony biofilms by micellar-encapsulated eugenol and carvacrol

The antimicrobial efficacy of carvacrol and eugenol, two essential oil compounds, encapsulated in a micellar nonionic surfactant solution on four strains of Listeria monocytogenes (Scott A, 101, 108, and 310) and four strains of Escherichia coli O157:H7 (H1730, E0019, F4546, and 932) growing as colony biofilms was investigated. Carvacrol and eugenol were encapsulated in Surfynol 485W at concentrations ranging from 0.3 to 0.9% (wt/wt) at a surfactant concentration of 5% (wt/wt). Colony biofilms were grown on polycarbonate membranes resting on agar plates containing antimicrobial formulations. Cells were enumerated after 0, 3, 6, 9, 24, 48, and 72 h of incubation. Colony biofilms of all E. coli O157:H7 strains were more sensitive to both antimicrobial systems than L. monocytogenes strains. Surface-grown E. coli O157:H7 viable cell numbers decreased below detectable levels after exposure to encapsulated essential oil compounds for > 3 h at all tested concentrations, except for E. coli O157:H7 F4546, which grew slowly in the presence of < 0.5% (wt/wt) eugenol. L. monocytogenes Scott A and 101 were more resistant to eugenol than carvacrol at sublethal concentrations (< 0.5% [wt/wt]). Carvacrol was effective at any concentration against L. monocytogenes 108, whereas concentrations of > 0.5% (wt/wt) eugenol were required for inactivation. L. monocytogenes 310 was equally sensitive to both essential oil compounds. Results suggest that surfactant-encapsulated generally recognized as safe essential oil compounds may offer a new means to control the growth of food pathogens such as E. coli O157:H7 and L. monocytogenes on food contact surfaces.     

In-cabin commuter exposure to ultrafine particles on Los Angeles freeways

Worldwide people are exposed to toxic ultrafine particles (UFP, with diameters (dp) less than 100 nm) and nanoparticles (NP, dp < 50 nm) under a variety of circumstances. To date, very limited information is available on human exposure to freshly emitted UFP and NP while traveling on major roads and freeways. We report in-cabin and outdoor measurements of particle number concentration and size distributions while driving three vehicles on Los Angeles freeways. Particle number concentrations and size distributions were measured under different vehicle ventilation settings. When the circulation fan was set to on, with substantial external air intake, outside changes in particle counts caused corresponding in-cabin changes approximately 30-60 s later, indicating an maximal air exchange rate of about 120-60 h(-1). Maximum in-cabin protection (approximately 85%) was obtained when both fan and recirculation were on. In-cabin and outdoor particle size distributions in the 7.9-217 nm range were observed to be mostly bimodal, with the primary peak occurring at 10-30 nm and the secondary at 50-70 nm. The vehicle's manufacture-installed particle filter offered an in-cabin protection of about 50% for particles in the 7-40 nm size range and 20-30% for particles in the 40 to approximately 200 nm size range. For an hour daily commute exposure, the in-vehicle microenvironment contributes approximately 10-50% of people's daily exposure to UFP from traffic.     

Stable metal isotopes reveal copper accumulation and loss dynamics in the freshwater bivalve Corbicula

Characterization of uptake and loss dynamics is critical to understanding risks associated with contaminant exposure in aquatic animals. Dynamics are especially important in addressing questions such as why coexisting species in nature accumulate different levels of a contaminant. Here we manipulated copper (Cu) stable isotopic ratios (as an alternative to radioisotopes) to describe for the first time Cu dynamics in a freshwater invertebrate, the bivalve Corbicula fluminea. In the laboratory, Corbicula uptake and loss rate constants were determined from an environmentally realistic waterborne exposure to 65Cu (5.7 microg L(-1)). That is, we spiked deionized water with Cu that was 99.4% 65Cu. Net tracer uptake was detectable after 1 day and strongly evident after 4 days. Thus, short-term exposures necessary to determine uptake dynamics are feasible with stable isotopes of Cu. In Corbicula, 65Cu depuration was biphasic. An unusually low rate constant of loss (0.0038 d(-1)) characterized the slow component of efflux, explaining why Corbicula strongly accumulates copper in nature. We incorporated our estimates of rate constants for dissolved 65Cu uptake and physiological efflux into a bioaccumulation model and showed that dietary exposure to Cu is likely an important bioaccumulation pathway for Corbicula.     

黑果枸杞花色苷纳米颗粒的制备及其对氧化低密度脂蛋白诱导的人脐静脉融合细胞氧化损伤的保护作用

为了提高黑果枸杞花色苷的稳定性和活性,利用壳聚糖（chitosan,CS）与酪蛋白磷酸肽（casein phosphopeptide,CPP）复合凝胶体系制备CS-CPP黑果枸杞花色苷纳米颗粒。所得最佳制备条件为：pH?4、室温条件下搅拌,2?mg/mL黑果枸杞花色苷溶液等体积添加到质量分数0.5%?CPP溶液中,然后添加等体积0.20～0.30?mg/mL?CS溶液至上述花色苷-CPP溶液中,由离子凝胶机制自发形成CS-CPP黑果枸杞花色苷纳米颗粒。所得CS-CPP黑果枸杞花色苷纳米颗粒粒径为215.3?nm,表面电势为36?mV,包封率为65.0%～72.2%;体外释放实验结果表明,在pH?7.0时该CS-CPP黑果枸杞花色苷纳米颗粒的释放率为24.3%～64.2%。体外细胞实验结果表明,黑果枸杞花色苷质量浓度为100～200?μg/L的CS-CPP黑果枸杞花色苷纳米颗粒能够显著提高氧化低密度脂蛋白诱导的氧化损伤人脐静脉融合EAhy926细胞的存活率（P＜0.05）。因此,CS-CPP复合凝胶体系能够包封黑果枸杞花色苷,其制备的CS-CPP黑果枸杞花色苷纳米颗粒具有较好的体外抗氧化能力。     

Copper--alumina--organic matter mixed systems: alumina transformation and copper speciation as revealed by EPR spectroscopy

The chemical forms and solubility of Cu in alumina-organic matter systems were studied separately (Cu/Al and Cu/OM) and in mixtures (Cu/Al/OM) during long-term (up to 8 years) equilibrations at pH 6 and 7.5. The transformation of alumina was monitored by XRD, while the chemical forms of Cu were probed by EPR spectroscopy. Total dissolved Cu was determined by voltammetry. Alumina transformation to gibbsite was more rapid and complete in the Cu/Al system equilibrated at pH 7.5 than at pH 6. The presence of colloidal organic matter (Cu/Al/OM) retarded the transformation of alumina. This effect was more pronounced in the system aged at pH 7.5, likely due to the higher pH that promotes formation of Al3+--organic matter coordination complexes. As expected, the systems at pH 7.5 resulted in lower dissolved Cu concentrations than corresponding systems at pH 6. After long-term equilibrations (8 and 5 years) at pH 6 and 7.5, however, the alumina-containing coprecipitates resulted in the lowest concentrations of Cu in solution (Cu/Al < Cu/Al/OM < Cu/OM). Analyses by EPR spectroscopy indicated that Cu forms inner-sphere complexes in all systems at both pH values. Changes in the chemical forms of coprecipitated Cu (Cu/Al and Cu/Al/OM systems) occurred with time and included Cu occupying discrete sites where Cu-O-Al bond formation was dominant followed by formation of clusters (Cu-O-Cu associations) and in some cases precipitates. The anisotropic EPR parameters of the Cu/OM systems suggested that stronger interactions exist between Cu and organic matter functional groups as compared to Cu interactions with alumina-containing coprecipitates; yet, Cu solubility was highest in the Cu/OM systems. The geochemical processes described in this investigation may be effective in forest soils and wastewater treatment plants where Al and Fe salts are used as flocculation agents and to remove metal contaminants from solution.     

Waterborne versus dietary zinc accumulation and toxicity in Daphnia magna: a synchrotron radiation based X-ray fluorescence imaging approach

Recent studies have suggested that exposure of the freshwater invertebrate Daphnia magna to dietary Zn may selectively affect reproduction without an associated increase of whole body bioaccumulation of Zn. The aim of the current research was therefore to investigate the hypothesis that dietary Zn toxicity is the result of selective accumulation in tissues that are directly involved in reproduction. Since under field conditions simultaneous exposure to both waterborne and dietary Zn is likely to occur, it was also tested if accumulation and toxicity under combined waterborne and dietary Zn exposure is the result of interactive effects. To this purpose, D. magna was exposed during a 16-day reproduction assay to Zn following a 5 × 2 factorial design, comprising five waterborne concentrations (12, 65, 137, 207, and 281 μg Zn/L) and two dietary Zn levels (49.6 and 495.9 μg Zn/g dry wt.). Tissue-specific Zn distribution was quantified by synchrotron radiation based confocal X-ray fluorescence (XRF). It was observed that the occurrence of reproductive inhibition due to increasing waterborne Zn exposure (from 65 μg/L to 281 μg/L) was accompanied by a relative increase of the Zn burdens which was similar in all tissues considered (i.e., the carapax, eggs, thoracic appendages with gills and the cluster comprising gut epithelium, storage cells and ovaries). In contrast, the impairment of reproduction during dietary Zn exposure was accompanied by a clearly discernible Zn accumulation in the eggs only (at 65 μg/L of waterborne Zn). During simultaneous exposure, bioaccumulation and toxicity were the result of interaction, which implies that the tissue-specific bioaccumulation and toxicity following dietary Zn exposure are dependent on the Zn concentration in the water. Our findings emphasize that (i) effects of dietary Zn exposure should preferably not be investigated in isolation from waterborne Zn exposure, and that (ii) XRF enabled us to provide possible links between tissue-specific bioaccumulation and reproductive effects of Zn.     

铬黑T光度法测定粮食中的微量铜

建立光度法测定粮食中微量铜(Ⅱ)的新方法。研究表明,pH 10.0硼酸-氯化钾-氢氧化钠缓冲介质中,铜(Ⅱ)与铬黑T发生灵敏的显色反应,生成桃红色的配合物,当显色时间20min,显色剂用量达2.5mL时为最佳条件。配合物最大吸收波长为540nm,表观摩尔吸光系数(ε)为2.99×104L/(mol·cm),铜(Ⅱ) 在0～1.2μg/mL范围内遵循比尔定律。样品测定结果与原子吸收分光光度法的测定结果一致。     

Effect of humic and fulvic acid concentrations and ionic strength on copper and lead binding

We investigated the influence of humic and fulvic acid concentration (in the range of 1-1000 mg/L) on the binding of the two trace metals Cu(II) and Pb(II). The ability of the non-ideal competitive adsorption (NICA)-Donnan model to correctly predict Cu and Pb binding at low humic or fulvic acid concentration and lower ionic strength (0.01 M NaNO3), based on model parameters obtained from experiments conducted at high humic or fulvic acid concentrations (approximately 1000 mg/L) and higher ionic strength (0.1 M NaNO3), was tested. The binding of Cu and Pb to humic and fulvic acid in 0.01 M NaNO3 was determined over wide ranges in proton and metal ion activities using three different methods: ligand exchange-adsorptive differential pulse cathodic stripping voltammetry at low humic or fulvic acid concentrations (1-3 mg/L), differential pulse anodic stripping voltammetry at intermediate humic or fulvic acid concentrations (10-20 mg/L), and ion-selective electrodes at high humic or fulvic acid concentrations (approximately 1000 mg/L). The results demonstrate that binding isotherms for Cu and Pb can be measured at low humic or fulvic acid concentration using suitable voltammetric techniques. The binding isotherms for Cu and Pb to humic and fulvic acid obtained at constant pH values in the range of pH 4-8 are shown to be independent of humic and fulvic acid concentration. The NICA-Donnan model, calibrated for Cu and Pb binding using data measured at high humic and fulvic acid concentrations and an ionic strength of 0.1 M, accurately predicts Cu and Pb binding at low humic and fulvic acid concentrations and lower ionic strength (0.01 M). We conclude that NICA-Donnan parameters obtained by fitting experimental data measured with ion-selective electrodes at high humic or fulvic acid concentrations can be used for geochemical modeling of soils and aquatic environments with much lower concentrations of humic or fulvic acids.     

Nano-CeO2 exhibits adverse effects at environmental relevant concentrations

Ceria nanoparticles (nano-CeO(2)), due to their widespread applications, have attracted a lot of concern about their toxic effects on both human health and the environment. The present work aimed to evaluate the in vivo effects of nano-CeO(2) (8.5 nm) on Caenorhabditis elegans (C. elegans) at environmental relevant concentrations (molar concentrations ranging from 1 nM to 100 nM). The results indicate that nano-CeO(2) could induce ROS accumulation and oxidative damage in C. elegans, and finally lead to a decreased lifespan. The most surprising thing is that the mean lifespan of nematodes was significantly decreased by 12% even at the exposure level of 1 nM (p < 0.01). In vitro tests suggest that the ability of nano-CeO(2) to catalyze ROS generation was involved in the mechanism for its toxicity to C. elegans. To our best knowledge, this is the first case in which nanoparticles exhibit adverse effects on organisms at such low concentrations (1nM-100 nM). So, our findings indicate the importance of nanotoxicological investigations at environmentally relevant concentrations and will attract more attentions on the risks of NPs exposure.     

基于表面增强拉曼光谱快速检测苹果汁中亚胺硫磷

利用种子生长法合成出不同大小(35～91nm,金核19nm;66～127nm,金核43nm)的金核银壳纳米粒子(Au-Ag NPs),对其形貌和光学特性进行表征,并将其作为表面增强拉曼散射(SERS)基底,探究不同粒径和金银比例对亚胺硫磷检测的影响。试验结果显示:42nm Au-Ag NPs(金核19nm)和78nm Au-Ag NPs(金核43nm)对亚胺硫磷标准溶液具有最佳的SERS增强效果,最低检出浓度可低至0.05mg/L。但Au-Ag NPs基底应用于苹果汁中亚胺硫磷的SERS快速检测效果存在较大差异,以42,78nm Au-Ag NPs作为增强基底时,苹果汁中的亚胺硫磷最低检出浓度分别为5.0,0.5 mg/L。研究表明通过筛选出合适的粒径及金银比例的Au-Ag NPs有望实现对果汁中亚胺硫磷的现场快速检测。     

Perfluorinated compounds in fish and blood of anglers at Lake Möhne, Sauerland area, Germany

Perfluorinated compounds (PFCs) were measured in fish samples and blood plasma of anglers in a cross-sectional study at Lake Mo?hne, Sauerland area, Germany. Human plasma and drinking water samples were analyzed by solid phase extraction, high-performance liquid chromatography (HPLC), and tandem mass spectrometry (MS/MS). PFCs in fish fillet were measured by ion pair extraction followed by HPLC and MS/MS. PFOS concentrations in 44 fish samples of Lake Mo?hne ranged between 4.5 and 150 ng/g. The highest median PFOS concentrations have been observed in perches (median: 96 ng/g) and eels (77 ng/g), followed by pikes (37 ng/g), whitefish (34 ng/g), and roaches (6.1 ng/g). In contrast, in a food surveillance program only 11% of fishes at retail sale contained PFOS at detectable concentrations. One hundred five anglers (99 men, 6 women; 14-88 years old; median 50.6 years) participated in the human biomonitoring study. PFOS concentrations in blood plasma ranged from 1.1 to 650 μg/L (PFOA: 2.1-170 μg/L; PFHxS: 0.4-17 μg/L; LOD: 0.1 μg/L). A distinct dose-dependent relationship between fish consumption and internal exposure to PFOS was observed. PFOS concentrations in blood plasma of anglers consuming fish 2-3 times per month were 7 times higher compared to those without any fish consumption from Lake Mo?hne. The study results strongly suggest that human internal exposure to PFC is distinctly increased by consumption of fish from PFC-contaminated sites.     

Preparation of nano‐ZnO using sonication method and its antibacterial characteristics

The antibacterial activity of zinc oxide nanoparticles prepared by sonication method was evaluated in this paper. Effect of calcination conditions on the size and antibacterial activity of zinc oxide nanoparticles was investigated. Zinc oxide nanoparticles were characterised for purity (Thermo Gravimetric Analyzer), crystallinity and crystal size (XRD), particle size and morphology (TEM), etc. Results showed that the smallest size 8 nm could be obtained. The lethal experiments of nanocrystalline zinc oxide were evaluated on Lactobacillus plantarum. All L. Plantarum were killed after 24‐h exposure at 1000 ppm. With the increase in calcination time, the lethal effect of ZnO nanoparticles was increased after 6‐h exposure at 100 or 1000 ppm.     

Formation of Biocompatible Nanoparticles via the Self-Assembly of Chitosan and Modified Lecithin

ABSTRACT:  The formation of biocompatible nanoparticles via the self-assembly of chitosan (CHI) and modified lecithin (ML) was studied. Stable nanoparticles in the size range of 123 to 350 nm were formed at over a wide molar mixing ratios of CHI/ML solutions (amino group/phosphate group) (NH₃⁺/PO₃⁻) and total polyelectrolyte (PE) concentrations (0.1 to 1 wt%) except at intermediate molar ratios when the surface charge was close to neutrality. Zeta-potentials of the nanoparticles were found to be independent of the total PE concentrations. Nanoparticles exhibited excellent stability at over an extended pH (pHs 3 to 6) and ionic strength range (≤ 500 mM NaCl concentration). The particle size and zeta-potential of the nanoparticles increased with the molecular weight of CHI. Transmission electron microscopy suggested that nanoparticles were generally spherical in shape with CHI constituting the exterior of its surface at high molar mixing ratios. Dextran-fluorescein isothiocyanate, bovine serum albumin, and Coomassie brilliant blue as models of nonionic, positively and negatively charged compounds were encapsulated within the nanoparticles at between 8.7% and 62.7% efficiency. The ability of the nanoparticle suspensions to be converted to lyophilized powder or concentrated suspension was also demonstrated.