The effect of increased extraction of forest harvest residues on soil organic carbon accumulation in Sweden

The demand and potential for increasing the use of bioenergy from harvest residues in Sweden are large. However, harvest residue (branches and tops) and stump extraction negatively affect soil organic carbon (SOC) accumulation. The main objective of this study was to assess the effects of increased harvest residue extraction on soil organic carbon (SOC) accumulation at national level. Further, the reduction in CO2 by substituting coal with biofuel from harvest residues and stumps was assessed. Several scenarios with increased harvest residue extraction were simulated with the forest management system HUGIN and the SOC decomposition model Q and the effects on SOC accumulation in Swedish coniferous forest soils were assessed. All scenarios resulted in decreased SOC accumulation. The decrease in SOC accumulation was largest for stump extraction, with 0.15 Mg C ha⁻¹ y⁻¹ loss on average over a 100-year simulation period. In all scenarios, the short-term effects on SOC accumulation were greater than the long-term effects. The effect of substituting coal with bioenergy was an immediate reduction of net CO₂ emissions. An increase in the use of forest residues leads to CO₂ mitigation in the atmosphere, even when SOC losses are accounted for.     

Bio-oil production via fast pyrolysis of shrub residues in a fluidized-bed reactor

In this article, the shrub residues as raw materials were produced to fast pyrolysis oil (called bio-oil) in a 5-kg/h fluidized-bed reactor. The optimum conditions were obtained at 500°C, flow rate of fluidizing gas of 4 m³/h, and feed rate of 3 kg/h. The liquid yield was up to 60% at the optimum conditions. The bio-oil was easy to divide into two phases: oil phase and aqueous phase. The high heat value of the oil phase was up to 18.55 MJ/kg, but the high heat value of the aqueous phase was only 0.72 MJ/kg. The oil phase and aqueous phase both have lower pH values. The oxygen content was up to 50%, while the sulfur and nitrogen content were very low. Owing to the higher oxygen content and lower pH value in liquid products, it must be further upgraded to bio-oil before application.     

Use of solid residue from olive kernel pyrolysis for polymer matrix composite manufacturing: Physical and mechanical characterization

This study is aiming at the production of carbon material from agricultural residues by pyrolysis and their further use for the production of green polymeric composites. The development of an agricultural‐based polymer matrix compatible with olive pits and consequently a fully biodegradable composite system is the future and ultimate goal of the undertaken research. In this study, pyrolysis of olive kernels was conducted at 800°C for 1 h. Furthermore, elemental, proximate, and metal analyses were performed for to the raw material and the produced char. The analyses showed that the pyrolytic char from olive kernel is a carbon rich material with significant concentration in metals, which can be further studied as additive for the production of green materials. For that purpose, samples made out of epoxy matrix, reinforced with pyrolytic char from olive kernel at different concentrations, were manufactured and mechanically characterized at three point bending conditions. A maximum increase of 60% in bending modulus in comparison to the net matrix modulus was achieved. The new material developed in the present investigation is a green composite with an elastic modulus 60% higher than that of the pure matrix. Results were also compared with predictions derived by the application of a theoretical model previously developed by the first author for the evaluation of the elastic modulus in particulate composites taking into account not only the effect of filler‐matrix adhesion but also the degree of dispersion of fillers into the matrix. It was found that predicted values as derived from the application of the model were in very good agreement with experimental findings. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

碘化钾-淀粉体系分光光度法测定食品中亚硝酸钠含量

在酸性氯化钠介质中,碘化钾与亚硝酸钠反应析出碘,加入淀粉后形成最大吸收波长为581 nm的蓝色配合物。结果表明,亚硝酸钠浓度范围为0.05~0.50μg/m L时,加入的亚硝酸钠含量(x/(μg·m L-1))与溶液在581 nm处的吸光度(y)呈良好的线性关系,线性回归方程y=1.627 5x+0.000 9,线性相关系数r=0.999 6。该方法用于火腿肠中亚硝酸钠含量的测定,结果与国家标准的盐酸萘乙二胺分光光度法相近。     

Optimisation of bio-oil production by hydrothermal liquefaction of agro-industrial residues: Blackcurrant pomace (Ribes nigrum L.) as an example

This work reports bio-oil production by hydrothermal liquefaction of blackcurrant pomace (Ribes nigrum L.), a fruit residue obtained after berry pressing. The bio-oil has a higher heating value of 35.9 MJ kg⁻¹ and low ash content, which makes it suitable for energy applications. We report the influence of process parameters on yields and carbon distribution between products: temperature (563–608 K), holding time (0–240 min), mass fraction of dry biomass in the slurry (0.05–0.29), and initial pH (3.1–12.8) by adding sodium hydroxide (NaOH). Depending on the experiments, the bio-oil accounts for at least 24% mass fraction of the initial dry biomass, while char yields ranges from 24 to 40%. A temperature of 583 K enhances the bio-oil yield, up to 30%, while holding time does not have a significant influence on the results. Increasing biomass concentrations decreases bio-oil yields from 29% to 24%. Adding sodium hydroxide decreases the char yield from 35% at pH = 3.1 (without NaOH) to 24% at pH = 12.8. It also increases the bio-oil yield and carbon transfer to the aqueous phase. Thermogravimetric analysis shows that a 43% mass fraction of the bio-oil boils in the medium naphtha petroleum fraction range. The bio-oil is highly acidic and unsaturated, and its dynamic viscosity is high (1.7 Pa s at 298 K), underlining the need for further upgrading before any use for fuel applications.     

Domain Motions and Functionally-Key Residues of l-Alanine Dehydrogenase Revealed by an Elastic Network Model

Mycobacterium tuberculosis l-alanine dehydrogenase (l-MtAlaDH) plays an important role in catalyzing l-alanine to ammonia and pyruvate, which has been considered to be a potential target for tuberculosis treatment. In the present work, the functional domain motions encoded in the structure of l-MtAlaDH were investigated by using the Gaussian network model (GNM) and the anisotropy network model (ANM). The slowest modes for the open-apo and closed-holo structures of the enzyme show that the domain motions have a common hinge axis centered in residues Met133 and Met301. Accompanying the conformational transition, both the 1,4-dihydronicotinamide adenine dinucleotide (NAD)-binding domain (NBD) and the substrate-binding domain (SBD) move in a highly coupled way. The first three slowest modes of ANM exhibit the open-closed, rotation and twist motions of l-MtAlaDH, respectively. The calculation of the fast modes reveals the residues responsible for the stability of the protein, and some of them are involved in the interaction with the ligand. Then, the functionally-important residues relevant to the binding of the ligand were identified by using a thermodynamic method. Our computational results are consistent with the experimental data, which will help us to understand the physical mechanism for the function of l-MtAlaDH.     

抗生素和其他兽药残留的危害

本文较为详细地介绍了动物性食品抗生素残留的危害，如细菌耐药性的普遍产生，易导致二重感染，扰乱机体微生态，药物对机体的直接不良反应、直接毒性作用，各种变态反应等等，本文也简要描述了其他兽药非抗生素兽药和激素的毒副作用，列举了我国违禁兽药清单。     

Detection of 3-amino-2-oxazolidinone (AOZ), a tissue-bound metabolite of the nitrofuran furazolidone, in prawn tissue by enzyme immunoassay

Furazolidone, a nitrofuran antibiotic, is banned from use in food animal production within the European Union. Increasingly, compliance with this ban is monitored by use of analytical methods to detect a stable tissue-bound metabolite, 3-amino-2-oxazolidinone (AOZ). Widespread use of furazolidone in poultry and prawns imported into Europe highlighted the urgent need for development of nitrofuran immunoassay screening tests. The first enzyme-linked immunoabsorbant assay for detection of AOZ residues in prawns (shrimps) is now described. Prawn samples were derivatized with o-nitrobenzaldehyde, extracted into ethyl acetate, washed with hexane and applied to a competitive enzyme immunoassay based on a rabbit polyclonal antiserum. Assay limit of detection (LOD) (mean + 3 s) calculated from the analysis of 20 known negative cold and warm water prawn samples was 0.1 µg kg^-1. Intra- and interassay relative standard deviations were determined as 18.8 and 38.2%, respectively, using a negative prawn fortified at 0.7 µg kg^-1. The detection capability (CC_β), defined as the concentration of AOZ at which 20 different fortified samples yielded results above the LOD, was achieved at fortification between 0.4 and 0.7 µg kg^-1. Incurred prawn samples (n = 8) confirmed by liquid chromatography coupled with tandem mass spectrometry detection to contain AOZ concentrations between 0.4 and 12.7 µg kg^-1 were all screened positive by this enzyme-linked immunoabsorbant assay. Further data are presented and discussed with regard to calculating assay LOD based on accepting a 5% false-positive rate with representative negative prawn samples. Such an acceptance improves the sensitivity of an ELISA and in this case permitted an LOD of 0.05 µg kg^-1 and a CC_β of below 0.4 µg kg^-1.     

Aflatoxin and its metabolites in tissues from laying hens and broiler chickens fed a contaminated diet

Two groups of 32 hens and broiler chickens were contaminated with 2.5 and 5 mg of aflatoxin (AF) kg^?1 feed for a period of 32 days. During this contamination 16 birds were sacrificed and aflatoxin and its metabolites were detected using thin-layer chrotnatography and fluorescence densisometry. The tissues analysed (liver, muscle, kidney, gizzard and eggs) gave a wide range of concentrations, the lowest was found in ben muscle (0.05 μg kg^?1 of AFB₁) and the highest in gizzards from the 5 mg kg^?1 group of the hens (9.01 μg kg^?1 of AFB₁). Metabolites of AFB₁, AFM, and AFB_2a appeared in the liver but not in other tissues. In broiler's tissues, the following metabolities were isolated: AFM₁ and AFB_2a, in liver, aflatoxicol in muscle and AFM₁ and AFB_2a in kidneys, all having concentrations lower than AFB₁. Aflatoxicol was isolated from one egg sample (0.32 μg kg^?1). For both types of birds, aflatoxin clearance time was only 24 h for muscle and kidneys. In livers from the 5 mg kg^?1 group, AFM₁ and AFB_2a were still found 4 days after removal of the contaminated feed. In eggs and gizzards, aflatoxin residue was still detected on the 8th day of the clearance period although in low quantities. In the broiler's gizzards, clearance time was only 24 h. These results suggest that aflatoxin transfer to edible tissues is very small and the danger of contaminations to humans is also very small, except in the case of gizzards.     

河北省梨主产区梨果农药残留风险研究

目的掌握河北省梨果中农药残留分布情况及污染风险程度,为河北省梨果的质量安全监管提供基础数据。方法采集河北省2013~2014年11个梨主产县(市)的85份梨果样品,采用气相色谱和超高效液相色谱-串联质谱法对梨果中110种农药残留状况进行检测,检测结果与国家规定的梨果中农药最大残留限量进行比对分析,并运用污染指数法对农药残留水平进行风险评价。结果 85个样品共检出24种农药残留,每种样品均检测出农药残留,农药品种1~8种不等,检出率100%,但均不存在农药残留超标现象。检测出的24种农药中以农药杀虫剂为主,其中多菌灵和吡虫啉的检出率分别为69%和62%,明显高于其他种类农药。1个样品检测出禁用农药克百威。此次采样的十一个县或县级市中,石家庄赵县和沧州泊头市的样品达到1级安全水平的比率为100%,其余县市1级安全水平样本比率在40%~90%不等,肃宁、阜城、深州和河间等县(市)的样本综合污染指数在2级(相对安全)的样本比率较高,风险程度高于其他县市。结论河北省梨果农药残留水平低,总体上处于安全范围内,风险程度小,但不同县(市)的农药残留风险程度存在地域差异性。