Aflatoxin and fumonisin contamination of yam flour from markets in Nigeria

The natural occurrence of aflatoxins (AFs) and fumonisins (FBs) in yam flour samples (n = 100) obtained in south-western Nigeria was evaluated. AFs were determined by HPLC with fluorescence detection and FBs by HPLC coupled with mass spectrometry. Aflatoxin B₁ (AFB₁) and aflatoxin G₁ (AFG₁) were found in 57% and 21% of flours from white yam with concentrations ranging from <0.02 (limit of detection, LOD) to 3.2 μg kg⁻¹ (mean = 0.4 μg kg⁻¹) and from <0.05 to 3.5 μg kg⁻¹, respectively. AFB₁ was the only aflatoxin detected in samples from water yam, contaminating 32% of the samples with values ranging from <LOD to 0.6 μg kg⁻¹ (mean = 0.1 μg kg⁻¹). Fumonisin B₁ was found in 32% of the white yam samples (<0.5 (LOD) to 91 μg kg⁻¹; mean = 5 μg kg⁻¹) and in 5% of water yam samples (<LOD to 2 μg kg⁻¹). AFs and FBs were significantly higher (P < 0.05) in white yam flours compared to water yam flours. Preparation of amala from naturally-contaminated yam flour resulted in reduction of AFB₁ and AFG₁ by 44% and 51% respectively. From this study, only 7% of the samples contained AFs above the European standard limits for cereals intended for direct human consumption, while all the FBs-positive samples were well below the limits. The occurrence of ochratoxin A, zearalenone and deoxynivalenol was also evaluated in 20 samples; these mycotoxins were never detected.     

Comparison study of three rapid test kits for histamine in fish: BiooScientific MaxSignal enzymatic assay, Neogen Veratox ELISA, and the Neogen Reveal Histamine Screening test

Two new test kits for quantifying histamine in fish are investigated and compared to the Neogen Veratox ELISA. One of the kits is based on selective enzymatic conversion of histamine by histamine dehydrogenase (MaxSignal, BIOO Scientific, Austin, Texas) and the other is dipstick based on lateral flow immuno-chromatography (LFIC). These new kits are compared to Veratox using spiked and naturally contaminated fresh and frozen yellowfin tuna and mahi mahi, as well as canned mackerel in broth and canned tuna in oil and in broth. Histamine levels determined using the MaxSignal enzymatic kit in spiked and naturally contaminated fish were strongly correlated with levels detected with the Veratox ELISA. Comparing both new kits and also using the AOAC performance tested Veratox, spiking at 0 and 50 mg/kg, no false negatives or false positives were found over a wide range of concentrations of histamine. In contrast to competitive ELISA kits, which give a sigmoidal (logistics curve) color response that decreases with increasing analyte, the enzymatic kit gives a linear response, increasing with histamine concentration. Linearity is excellent and samples can be analyzed without further dilution using the included standards to quantify up to 70 mg/kg histamine free base. The 450 nm endpoint color develops rapidly, and using a reaction time of 30 min, recoveries in canned tuna and mackerel were greater than 90% and apparent histamine levels reach a plateau versus time. In contrast, recoveries using the manufacturer’s recommended reaction time of 10 min were low, and further study supported the presence of naturally occurring inhibitors of histamine dehydrogenase in fish. Using an extended (30 min) reaction time, the enzymatic kit performed well and was still rapid. The simplicity of the procedure results in a kit more easily mastered and potentially more rugged than competitive ELISA assays, which require multiple incubations, a wash step, additional dilution steps, and twice as many pipetting steps. The LFIC kit Reveal was also found to be simpler and easier to use than ELISA kits, having only one critical pipetting step, requiring no acylation, and only minimal sample manipulation. If accelerated sample removal and grinding could be implemented and validated, the LFIC kit Reveal appears to have excellent potential for onsite testing.     

中美海相页岩气地质特征对比研究

通过中国海相页岩气详细研究和美国典型页岩气区带解剖,对比研究了中美页岩气地质特征的异同,这些研究对指导我国四川盆地海相页岩气的研究具有重要理论和实践意义。 ①美国Barnett页岩、Marcellus页岩和Haynesville页岩气区带的盆地类型为前陆盆地,中国四川早古生代盆地为克拉通。沉积环境均为深水陆棚,岩石类型以硅质和硅质钙质页岩为主,脆性矿物含量高。②Barnett页岩TOC值为3%~13%,平均为4.5%,Marcellus页岩TOC值为3%~12%,平均为4.0%,Haynesville页岩TOC值为0.5%~4%。四川盆地五峰组-龙马溪组和筇竹寺组页岩TOC值分别为1.5%~3%和2.5%~4.5%。③美国三大页岩成熟度适中,四川盆地海相页岩处于过成熟阶段。Barnett页岩、Marcellus页岩和Haynesville页岩R_O值分别为0.5%~2.1%、1.2%～3.5%和1.2%~3%。四川盆地筇竹寺组页岩R_O值一般为2.5%~4.5%,平均为3.5%,龙马溪组页岩R_O值为1.5%~3%。 ④Barnett页岩核心区厚度为30~180m,总孔隙度为4%~5%,基质渗透率小于1×10^-3μm²,Marcellus页岩厚度为 15～60m,孔隙度平均为10%,渗透率小于1×10^-3μm², Haynesville页岩厚度为70~100m,孔隙度为8%~9%,渗透率小于5×10^-3μm²,四川盆地五峰组-龙马溪组页岩厚度为25~120m,孔隙度为3%~10%,渗透率为(0.01~)×10^-3μm²,筇竹寺组页岩厚度为40~100m,孔隙度为0.1%~3%,渗透率为(0.01~42)×10^-3μm²。⑤Barnett页岩、Marcellus页岩和Haynesville页岩含气量分别为4.2~9.9m³/t、1.70～2.83m³/t和2.5~9m³/t。四川盆地五峰组-龙马溪组和筇竹寺组页岩含气量分别为1.7~4.5m³/t和0.55~1.2m³/t。中国海相页岩吸附气含量大于美国。⑥美国海相页岩埋深为1 220~3 990m,中国海相页岩埋深可高达5 000m,一般为1 500~4 000m;Barnett页岩和筇竹寺组页岩为正常地层压力,压力系数分别为0.99~1.01和1,Marcellus页岩,Haynesville页岩和五峰组-龙马溪组为异常高压,地层压力系数分别为0.9~1.4、1.61~2.07和1~2.3。⑦除四川盆地筇竹寺组页岩外,其他4套页岩均具有良好封盖层,有利于天然气保存。⑧美国地表条件更有利,多以平原为主,而四川多为丘陵。 ⑨四川盆地五峰组-龙马溪组页岩气地质资源量为17.5×10¹²m³,技术可采资源量为1.77×10¹²m³,筇竹寺组页岩气地质资源量为8.86×10¹²m³,技术可采资源量为0.886×10¹²m³。     

An initial characterization of aflatoxin B1 contamination of maize sold in the principal retail markets of Kigali,Rwanda

Food security considerations have shifted in recent years, with the recognition that available food should also be nutritious and safe. There is a growing evidence base for contamination of maize and other crops by fungal toxins in the tropics and sub-tropics. As an initial snapshot of contamination by one of these toxins in Rwanda, Aflatoxin B1 (AFB1) was analyzed in 684 samples of maize flour collected in seven principal retail markets of Kigali and in 21 samples of animal feed from seven feed vendors. Two rounds of sample collections were carried out, the first in September 2014 and the second in January 2015. A questionnaire given to vendors was used to determine if gender and education level of vendors, origin of maize and awareness of aflatoxins had any significant effect on AFB1 level in collected samples. Enzyme-Linked Immunosorbent Assay (ELISA) and Immuno-affinity fluorimetery were used to analyze samples. Only markets had a significant effect on AFB1 level; for the two collections, differences were inconsistent among markets. In the first round, market means of AFB1 varied between 8.0 ± 5.57 μg/kg and 24.7 ± 23.74 μg/kg and for the second round, between 10.4 ± 8.4 μg/kg and 25.7 ± 25.85 μg/kg. In most animal feed samples AFB1 was >100 μg/kg. None of the vendors interviewed was aware of the risk of mycotoxin contamination in their maize-based flours and feed. Limits set by the United States Food and Drug Administration (20 μg/kg) for total aflatoxins and European Commission (2 μg/kg) for AFB1 for maize flour imports, were varied between 2–35% and 66–100% of samples, respectively. The implications of this study for human and animal health in Rwanda suggest that expanded surveys are needed to understand the scope of contamination, given the influence of environment and other factors on aflatoxin accumulation. Available options to mitigate and monitor aflatoxin contamination can be further deployed to reduce contamination.     

Industry-level changes in microbial contamination on market hog and broiler chicken carcasses between two locations in the slaughter process

Pork and poultry products have been implicated in a substantial proportion of microbial foodborne illnesses such as salmonellosis and campylobacteriosis. Understanding the similarities and differences between the effectiveness of interventions applied during slaughter to the two commodities can help identify opportunities to reduce the risk of foodborne illness. This study uses data from two national surveys and censored data techniques to assess the concentrations of microbial contamination on broiler chickens and market hogs at two points in the slaughter process. Statistical distributions are fitted to estimate the average concentrations of microbial contamination, the variability in these concentrations, and the average reduction in contamination between the two locations for pork and chicken produced in the United States. The concentrations of Salmonella and generic Escherichia coli (GEC) are estimated for hog carcasses; the concentrations of Salmonella, GEC, and Campylobacter are estimated for chicken carcasses. These datasets are also used to study the magnitude of seasonal changes in concentrations of microbial contamination and to demonstrate the potential utility of using the reduction in the average aerobic plate count between the pre-evisceration and post-chill stages of the slaughter process as an indicator of the corresponding reduction in other species of bacteria. The study finds interventions for hog carcasses achieve much larger reductions in contamination than those applied to chicken. However, the variability in the concentration of Salmonella contamination on pork is significantly higher, suggesting an opportunity to decrease risk by ensuring more consistent reductions across the industry. The study also finds, for both commodities, that the log₁₀ reductions in the concentrations of GEC are similar to the log₁₀ reductions in Salmonella, while the log reduction in Campylobacter on chicken was substantially greater than for both GEC and Salmonella. Additional analyses demonstrate modest seasonal increases in contamination only on hog carcasses as well as demonstrating that reductions in APC are indicative of reductions in all other organisms, suggesting its potential as an effective indicator organism.     

Comparative study of imported food control systems of Taiwan,Japan, the United States,and the European Union

The growth of the global food trade has increased significantly over the last two decades. The purpose of this review paper is to compare imported food safety controls in Taiwan, Japan, the United States, and the European Union. Our key findings are: 1) imported food of animal and non-animal origin is by separate, competent authorities in Taiwan, Japan, and the US, whereas it is controlled by a single authority in the EU, 2) foreign facilities require registration in the US and Japan, 3) importing high-risk food in the EU, Taiwan and Japan requires the competent authority to inspect the food chain process and facilities in the third country, whereas a US FDA’s accredited third party auditor can do so in the US, 4) an advanced developed support systems for enabling the effectiveness and efficiency of imported food control can only be found in the EU and US. These findings may help the competent authorities responsible for imported food safety in Taiwan and the other countries to develop and enhance their own systems, not only to meet the international standards but importantly for the sake of public health protection.     

Air Emissions of Sulphur Dioxide From Gasoline and Diesel Consumption in the Southwestern States of Nigeria

The contribution of SO₂ emissions from the consumption of petroleum products to Nigerian airshed has been of great concern over the years because of the resulting adverse environmental and health effects. It is in the light of this that air emissions of SO₂ from gasoline and diesel consumed in the Southwestern States of Nigeria were estimated in this study. Lagos state being the highest consumer of gasoline and diesel in Southwestern Nigeria emitted the highest quantity.     

美国致密油开发现状及启示

美国页岩气勘探开发目前已进入快速发展阶段,同时也带动了页岩地层内致密油的开发。文中所指的致密油,是指以吸附或游离状态赋存于渗透率极低的暗色页岩、泥质粉砂岩和砂岩夹层系统中的自生自储、连续分布的石油聚集。目前,美国致密油的开发集中在Bakken,Eagle Ford和Barnett页岩区带内。其中Bakken致密油资源量为230×108t,可采资源量为5.9×108t,待发现资源量为3.7×108t油及相近数量的伴生气,2000年至今累计产油约2800×104t;Eagle Ford致密油赋存于区带北部,年产油约20×104t;Barnett待发现石油平均资源量为1400×104t,待发现致密油资源量为480×104t,其北区主要产油、南区主要产气,目前拥有8000余口生产井,截至2009年底,＂致密油带＂累计产油量达770×104t。我国广泛发育富有机质页岩,致密油的勘探潜力较大。     

Concentration of ochratoxin A in breakfast cereals and snacks consumed in the United States

A total of 144 breakfast cereal and snack samples collected from six areas in the United States (U.S.) were surveyed for the presence of ochratoxin A (OTA). All samples are the processed products including mainly corn, oat, wheat, and rice. The analytical methods in this study were immunoaffinity columns (IAC) and high performance liquid chromatography (HPLC) with fluorescence detection (FLD). The method provided recoveries of OTA from all sample matrices in the range of 95–100%. The limits of detection and limits of quantification for OTA were 0.032 and 0.10 ng/g for corn, wheat, and rice based samples; 0.038 and 0.12 ng/g for oat based samples, respectively. Analytical results showed that 75 samples (52%) were contaminated with OTA in the range of 0.10 and 7.43 ng/g. Among the OTA contaminated samples, 40% were labeled as organic and 60% were conventional with mean concentrations of 1.21 and 1.07 ng/g, respectively. There were ten contaminated samples, all from oat based products, exceeding the maximum limits for OTA by European Commission Regulation (3 ng/g) in cereal based products.     

Geochemical investigation of trace elements in crude oils from two different depobelts in the Niger Delta basin,Nigeria

The concentrations of trace elements in crude oil samples from the Northern and Central swamps depobelts in the Niger Delta basin were investigated using Flame Atomic Absorption Spectrometer. The origin, source facies, and depositional environment of organic matter that produced the oils were determined based on the trace elements concentrations. The concentrations of the trace elements (Cr, Cu, Fe, Mn, Ni and V) ranged from 0.04 to 5.71 ppm. Iron is the most abundant element in the samples while Cr has the least concentration. The results from trace metal geochemistry showed that the Niger Delta oils were derived predominantly from terrestrial organic matter deposited in the oxic depositional environment. The concentrations and ratios of nickel and vanadium grouped the oils into two distinct families reflecting the depobelt the oils belong. This observation indicates that the source rocks in the two depobelts were formed from organic matter of different source facies.     

Development of lateral flow immunoassay for rapid control and quantification of the presence of the colorant Sudan I in spices and seafood

The lateral flow immunoassay for colorant Sudan I detection was developed using the monoclonal antibody to Sudan I conjugated with gold nanoparticles. Conditions of the assay were optimized for both qualitative control and quantification of Sudan I in food matrixes with minimal dilution of the extracting media (final content of methanol – 50%). In the case of photometric registration, the limit of Sudan I detection in extracts was 2.5 ng/mL (which corresponds to 10 μg/kg of food and spices), and the working range of determined concentrations was 13–240 ng/mL. The average error of measurements varied from 5.5 to 16.9%. The visual limit of detection, which is the minimum concentration causing absence of visible coloration at the test zone, was 1 μg/mL. The assay efficiency was confirmed by its application to determine Sudan I content in highly colored spices (turmeric, curry) and seafood (caviar, mussels, fish). Thus, the developed assay is suitable as a rapid, inexpensive tool for revealing Sudan I quantification by mobile laboratories and in out-of-laboratory conditions.     

美国老油气区“挖潜”的有效措施

美国老油气区的“挖潜”富有成效。据统计，１９７８￣１９９１年美国老油气田的储量增长量占全美总探明储量增长量的９０％以上。     

中美页岩气勘探开发历程、地质特征和开发利用条件对比及启示

分析美国"页岩气革命"的成功经验对促进中国页岩气产业发展具有重要意义。对比研究中美两国页岩气的勘探开发历程、成藏地质条件、开发利用条件以及资源开发现状,结果表明:中美两国均拥有丰富的页岩气资源,但中国的页岩气勘探开发起步晚,资源探明率低,开发程度低,产量远低于美国,尚处于早期快速发展阶段。美国拥有得天独厚的页岩气成藏地质条件,优越的开发地质条件,完备的开发基础设施;美国在页岩气勘探开发方面的技术创新能力强,工艺技术全球领先,加上产业政策扶持等多种因素,共同促成了其页岩气产量的飞跃。与美国相比,中国的地质构造演化期次多,沉积盆地类型多,发育海相、海陆过渡相和陆相3种类型页岩,不同类型页岩的品质差异大;加之受晚期构造改造强烈,不同构造单元的页岩气保存条件差异大。中国页岩气主要分布区的地形地貌、地下地质条件复杂,开发基础设施相对薄弱,目前在立体高效开发等关键技术和工艺方面与美国存在较大差距。页岩气是中美天然气未来产量增长的主体,也是中国天然气产量增长的重要力量。建议:①进一步加快四川盆地五峰组—龙马溪组页岩气的勘探开发,实现增储上产;②进一步发挥公益性油气地质调查的引领作用,加强新区、新层系页岩气的地质调查和评价工作,开辟新的页岩气产能基地;③加强自主创新,强化成藏理论研究,攻关适合中国地表地质特点的关键技术工艺,促进深层、常压、陆相和海陆过渡相页岩气的低成本有效开发;④继续从政策方面给予扶持,促进页岩气产业快速发展。     

Origin and occurrence of crude oil in the Niger delta, Nigeria

Ten crude oils samples from onshore and offshore Niger delta were characterized based on their biomarkers and isotopic composition by Gas chromatography–Mass spectrometry and Isotope mass spectrometry. Abundance of pentacyclic triterpanes of hopane and oleanane skeletons and C₂₇–C₂₉ steranes in the oils indicates that they were formed from a mixed source (marine and terrestrial kerogen). The oleanane concentrations permit source grouping of the oils into three families.Various maturity parameters computed for the oils, especially those of aromatic biomarkers and aromatic sulfur compounds (thiophenes) to some extent reveal an increasing thermal maturity with increasing reservoir depths. The carbon isotope values lacked sufficient variation to distinguish maturity differences in the oils. This observation is quite revealing in that oils whose associate gases had earlier revealed a consistent increase in maturity with increasing depths, also have similar maturity values.The implication of this is that the oils and associated gases might have been formed at different levels of thermal maturity before being pooled together during migration into their present habitat.     

欧美清洁汽油的发展历程及对我国的启示

综述了美国、欧洲汽油质量标准变化历程以及清洁汽油质量升级采用的主要技术,分析了上述国家和地区汽油质量升级的路线和特点,总结了其汽油质量升级对我国清洁燃料发展的启示,提出了我国清洁汽油质量升级的建议及发展思路。     

Effect of UV-C treatment on the microbial population of white and red wines,as revealed by conventional plating and PMA-qPCR methods

Ultraviolet C (UV-C) irradiation is one of the emerging techniques for the inactivation of microorganisms in liquid food products, and it holds considerable promise also for treatment of wine. This application can be of particular interest to reduce or even eliminate the use of sulphur dioxide as a preservative in winemaking, given its potential health risks.In this study, UV-C light treatment was applied to ten different white and red wines during winemaking, for the first time at industrial scale, using a commercial turbulent flow system. The effect of 1.0 kJ/l dosage treatment on the viability of the natural microbial population, i.e., total yeasts, lactic acid bacteria and acetic acid bacteria, was investigated both with conventional plating and optimized specific propidium monoazide (PMA)-qPCR. Results of the two methods were mainly concordant for control and UV-C treated samples, and, in some cases, PMA-qPCR was able to detect small amounts of viable cells, probably in the VBNC state. Remarkably, PMA-qPCR allowed to obtain reliable results much faster than conventional plating methods.Data indicated that the UV-C irradiation was effective in reducing microbial counts for up to five log CFU/ml, depending on the wine (white or red) and on the microbial load of the sample. The treatment was much more effective in white wines: a statistically significant decrease was observed for putative spoilage-related bacteria, besides the most pronounced effect on yeast cells.Outcomes strongly support the applicability of UV-C treatment for white wine production, thanks to its efficacy towards all the microbial groups considered.     

Temporal patterns in the occurrence of Salmonella in raw meat and poultry products and their relationship to human illnesses in the United States

The prevalence and level of microbial pathogens on various commodities often exhibit seasonal patterns. As a consequence, the incidence of foodborne illness tends to follow these trends. Of the various product classes, the occurrence of microbial contamination can be high on raw meat and poultry products, with Salmonella potentially occurring in all meat and poultry product classes. Since 1999, the Food Safety and Inspection Service in the United States has collected samples of meat and poultry products and analyzed them for the presence of Salmonella. This study uses a common modeling approach to estimate the seasonal change in the proportion of test-positive samples for seven classes of raw meat and poultry products. The results generally support the hypothesis of a seasonal increase of Salmonella during the summer months. The proportions of test-positive samples decrease rapidly in the late fall for all product classes except chicken and ground turkey, which remain somewhat elevated through late winter. A comparison of the pathogens' seasonal pattern in meat and poultry with human cases reveals that the seasonal increase in human cases precedes the seasonal increase in meat and poultry by between one and three months. These results suggest that while contaminated meat and poultry products may be responsible for a substantial number of human cases, they are not necessarily the primary driver of the seasonal pattern in human salmonellosis.     

海上油气水多相管流中沿程摩阻因数分析

沿程摩阻因数是制约多相管流发展的关键,摩阻因数是压降计算的重要内容之一,其计算的准确性直接决定了压降计算的准确性。基于Xiao等人的流型判别法,将流型分为分层流、段塞流、环状流和分散泡状流等4种流型。分散泡状流仅需用到气体或液体与管壁之间的相互作用;分层流、环状流和段塞流不仅用到气体或液体与管壁之间的相互作用,还要用到气液界面之间的相互作用。气体或液体与管壁之间的沿程摩阻因数可以采用单相流体的沿程摩阻因数方法计算。对于不同的流型,气液界面的摩阻因数计算方法也不同。     

鄂尔多斯盆地三叠系延长组7段深水碎屑流沉积特征及成因

为了明确不同类型深水碎屑流沉积特征及其成因,以鄂尔多斯盆地三叠系延长组7段深水重力流沉积为研究对象,综合测录井资料、岩心观察分析、薄片分析和定量统计,分析碎屑流沉积特征、总结沉积序列和探讨成因机制。研究表明：研究区的深水碎屑流主要发育砂质碎屑流、泥质碎屑流和泥流3种类型。砂质碎屑流沉积以块状砂岩最为常见,漂浮状泥质碎屑发育,单层厚度分布在0.24~1.10 m,平均厚度为0.55 m。泥质碎屑流沉积包含孤立块状沉积和与下伏块状砂岩成对产出两种类型,前者内部大量发育漂浮状泥岩撕裂屑及软沉积物变形构造,后者富含漂浮状泥质碎屑与砂质团块,单层厚度分布在0.21~1.29 m,平均厚度为0.60 m。泥流沉积包含孤立块状沉积和与下伏块状砂岩成对产出两种类型,前者整体为泥质砂岩或砂质泥岩,后者内部可见漂浮状成层排列的毫米级泥质碎片,单层厚度分布在0.20~0.60 m,平均厚度为0.30 m。高浓度砂质沉积物或泥质沉积物搬运过程中环境水体卷入导致的流体转化是形成砂质碎屑流、孤立块状泥质碎屑流和泥流沉积的主要原因。与下部块状砂岩相伴生的泥质碎屑流沉积多为流体侵蚀成因或砂体液化成因;与下部块状砂岩相伴生的泥流沉积包含流体减速膨胀导致的流体转化和碎屑颗粒的差异沉降等成因。     

Oil-source Rock Correlation and Distributions of Pyrrolic Nitrogen Compounds in Oils From the Niger Delta,Nigeria

The occurrence and distributions of carbazole compounds were investigated in crude oils from Niger Delta, Nigeria, by gas chromatography-mass spectrometry-mass spectrometry. Geochemical characterization of the oils and the available source rocks based on saturate and aromatic biomarkers showed that the oils have higher thermal maturity than the source rocks. All the oils are isotopically related and might have originated from the same source rocks. However, subtle maturity differences exist among the oils from the same field. C₂- carbazoles are the dominant components of the crude oils. 4-methylcarbazole is the most abundant of the methylcarbazoles isomers while 1,5-dimethylcarbazole occurs as the most abundant among the dimethylcarbazoles. The abundance of benzocarbazoles are low compared to the alkylcarbazoles. Cross plots of the methylcarbazoles and dimethylcarbazoles against Pr/Ph ratio showed that carbazoles distributions in the oils are not affected by source facies. However, the cross plots of C₁- carbazoles and C₂- carbazoles against the calculated vitrinite reflectance indicated that the carbazoles concentrations increase with increasing maturity.