Activated Biochar Prepared by Pomelo Peel Using H<Subscript>3</Subscript>PO<Subscript>4</Subscript> for the Adsorption of Hexavalent Chromium: Performance and Mechanism

Adsorption of hexavalent chromium (Cr(VI)) using pomelo peel activated biochar (PPAB) as a adsorbent was investigated. The characterization of the adsorbent was studied by Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and zeta potentials analysis. The results showed that the PPAB had a high microporous structure and the existence of organic compounds such as hemicellulose, cellulose, and lignin. Various parameters including initial Cr(VI) concentration, pH, and adsorbent dosage were studied. The results indicated that the adsorption process was pH dependent and maximum adsorption capacity of Cr(VI) was 57.637 mg/g at pH 2.0 and 35 °C with PPAB dosage of 0.05 g. The adsorption kinetics fitted well to the pseudo-second-order model and the correlation coefficients were greater than 0.999. The adsorption isotherm data could be better described with the Langmuir model, suggesting the homogeneous and monolayer adsorption. Moreover, the scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and Fourier transform infrared spectrum (FTIR) results showed that the surface of PPAB had plenty of developed pores after activation and the modification process was deemed to proceed between the O–H groups from pomelo peel and H₃PO₄ molecules. The main adsorption mechanism was attributed electrostatic interaction and ion exchange between the surface of PPAB and Cr(VI).     

基于时序Landsat遥感数据的新疆开孔河流域农作物类型识别

快速、准确地获取农作物类别信息对农业部门的生产管理、政策制定具有重要作用。目前基于时间序列数据进行农作物分类主要是采用长时间序列的中低分辨率影像,大量的混合像元限制了农作物的分类精度。在农作物分类的特征选择方面主要是采用归一化植被指数(normalized differential vegetation index, NDVI),而其他特征量的应用还相对较少。该文以新疆开孔河农业区为研究区域,利用2016年的Landsat7 ETM+、Landsat8 OLI影像数据集,基于时间加权的动态时间规整(time weighted dynamic time warping,TWDTW)方法开展农作物类型识别研究,主要包括香梨、小麦、辣椒、棉花等。根据野外采集的样本点构建主要农作物的NDVI和第一主成分(principal component analysis 1,PCA1)时间序列,以反映不同农作物间的物候差异。基于NDVI数据分别利用DTW和TWDTW算法计算各未知像元序列与标准序列间的相似性程度,得到农作物的分类结果,2种方法的分类精度分别为65.69%、82.68%,表明时间权重的加入提高了DTW算法识别不同农作物的能力。结合NDVI与PCA1后,TWDTW的分类精度又提高了2.61个百分点,部分农作物的误分现象明显减少,说明PCA1能够进一步扩大作物间的差异性,提高分类精度。同时,还通过选取有限时相的影像组合进行分类,试验结果表明TWDTW算法在中高分辨率数据较少的情况下能够得到较为满意的分类结果,说明TWDTW算法在中高分辨率影像越来越丰富的时代具有应用潜力。     

扰动方式对典型草原区路域植被和土壤的影响

[目的] 分析不同扰动方式对内蒙古典型草原区土壤理化性质及植被特征的影响,为探索路域生态环境恢复规律,采用合理的恢复措施提供科学依据。[方法] 以锡林郭勒草原区3条公路(G303锡市—阿巴嘎旗段、G207锡市—西乌珠穆沁旗段、G207锡市—乌日图塔拉苏木段)为研究对象,采用空间代替时间的方法,调查研究了不同恢复年限(1,5,15 a)与不同扰动方式(碾压、路堑、取土场、路堤)路域土壤和植被特征。[结果] ①扰动方式对土壤理化性质有显著影响,其中土壤容重表现为：碾压＞路堤＞路堑＞取土场。随恢复年限增加,土壤容重表现为向未扰动区容重靠近趋势。土壤含水率表现为：碾压＜路堑＜取土场＜路堤,总体呈随恢复年限延长而增大趋势。土壤有机碳、全磷和全钾含量皆表现出碾压样地最差,路堤样地最优。②植物群落丰富度指数随恢复年限的增加显先增高后降低最终趋于稳定趋势,其中恢复5 a物种多样性指数相比于恢复15 a高。③主成分分析得出,恢复15 a的路堤、路堑、取土场扰动综合排名较高,其综合得分分别达到了2.33,1.42,1.32,碾压扰动的综合得分均处在最低水平,得分相比于未扰动区有明显差距,说明对生态系统破坏较为严重。[结论] 受到扰动的土壤理化性质及植被指数与未扰动土壤对比有很大差异,填方的土壤养分含量较高,而挖方土壤与未扰动区域相比,养分含量有明显缺失,需加强对该扰动区域的生态保护力度。     

滇池流域半湿润常绿阔叶林的特征研究

2020年8月至2021年6月,采用典型选样法,对滇池流域半湿润常绿阔叶林进行了全面系统的调查,共设置31个样方,从群落学特征、物种组成以及分布特征等方面对流域内半湿润常绿阔叶林的特征进行研究。结果表明：流域内现存半湿润常绿阔叶林少,主要分布在流域的北部和西部,群落退化严重,表现为片段化突出、高度降低,呈萌生丛状,特有植物比例低,区系次生度高,群落建群种自然更新困难。调查样方明显分为5个类型（群系）,按分布点多少及面积大小排序为滇青冈林、滇石栎林、黄毛青冈林、元江栲林和高山栲林。5个群系间的Jaccard相似性指数介于0.1111～0.2566,整体表现为极不相似和中等不相似,反映了群系间界限明显。31个样方内有野生维管植物454种,隶属于106科266属。群落物种较丰富,但区系次生度达到48.92%,其中草本层受干扰后响应最显著,以下依次是灌木层、层间层、乔木层。研究结果可以为滇池流域半湿润常绿阔叶林的保护和管理提供参考依据。     

Improved bread-baking process using Saccharomyces cerevisiae displayed with engineered cyclodextrin glucanotransferase

A bread-baking process was developed using a potential novel enzyme, cyclodextrin glucanotransferase[3-18] (CGTase[3-18]), that had previously been engineered to have enhanced hydrolyzing activity with little cyclodextrin (CD) formation activity toward starch. CGTase[3-18] was primarily manipulated to be displayed on the cell surface of Saccharomyces cerevisiae. S. cerevisiae carrying pdeltaCGT integrated into the chromosome exhibited starch-hydrolyzing activity at the same optimal pH and temperature as the free enzyme. Volumes of the bread loaves and rice cakes prepared using S. cerevisiae/pdeltaCGT increased by 20% and 45%, respectively, with no detectable CD. Retrogradation rates of the bread and rice cakes decreased significantly during storage. In comparison to the wild type, S. cerevisiae/pdeltaCGT showed improved viability during four freeze-thaw cycles. The results indicated that CGTase[3-18] displayed on the surface of yeast hydrolyzed starch to glucose and maltose that can be used more efficiently for yeast fermentation. Therefore, display of an antistaling enzyme on the cell surface of yeast has potential for enhancing the baking process.     

Previous infection with virulent strains of Newcastle disease virus reduces highly pathogenic avian influenza virus replication,disease, and mortality in chickens

Highly pathogenic avian influenza virus (HPAIV) and Newcastle disease virus (NDV) are two of the most important viruses affecting poultry worldwide and produce co-infections especially in areas of the world where both viruses are endemic; but little is known about the interactions between these two viruses. The objective of this study was to determine if co-infection with NDV affects HPAIV replication in chickens. Only infections with virulent NDV strains (mesogenic Pigeon/1984 or velogenic CA/2002), and not a lentogenic NDV strain (LaSota), interfered with the replication of HPAIV A/chicken/Queretaro/14588-19/95 (H5N2) when the H5N2 was given at a high dose (10^6.9 EID₅₀) two days after the NDV inoculation, but despite this interference, mortality was still observed. However, chickens infected with the less virulent mesogenic NDV Pigeon/1984 strain three days prior to being infected with a lower dose (10^5.3–5.5 EID₅₀) of the same or a different HPAIV, A/chicken/Jalisco/CPA-12283-12/2012 (H7N3), had reduced HPAIV replication and increased survival rates. In conclusion, previous infection of chickens with virulent NDV strains can reduce HPAIV replication, and consequently disease and mortality. This interference depends on the titer of the viruses used, the virulence of the NDV, and the timing of the infections. The information obtained from these studies helps to understand the possible interactions and outcomes of infection (disease and virus shedding) when HPAIV and NDV co-infect chickens in the field.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-015-0237-5) contains supplementary material, which is available to authorized users.     

不同氮肥品种对砖红壤中铵态氮淋溶特征的影响

通过室内盆栽试验研究不同氮肥品种对砖红壤中铵态氮淋溶特征的影响.结果表明,渗漏液中NH4+-N累计淋溶量大小依次为:尿素>复混肥>碳铵>复合肥;不同氮肥品种处理的渗漏液中,NH4+-N浓度大小依次为:尿素>碳铵≈复混肥>复合肥;对各处理渗漏液中NH4+-N淋溶量Yt随时间t的变化,对照可以用对数方程lnY1=a+blnt来描述,施肥处理以抛物线方程Yt1/2=a+bt拟合效果最好;土壤剖面中NH4+-N含量表现为:各处理NH4+-N含量在20cm土层内无明显变化,而后随土层的增加呈近直线增加.种植玉米能显著减少NH4+-N累计淋溶量,降低各土层土壤的NH4+-N含量.     

10%世高水分散粒剂防治大蒜叶枯病

冬春早熟大蒜的种植在云南大理州已过1万hm2，由于受大蒜叶枯病( Pleospora herbarum )的危害，每年都造成较大的经济损失。在防治药剂的选择上，笔者先后筛选出了大生、山德山等代森锰锌类药剂对大蒜叶枯病有较好的预防效果〔1〕，而施保功、施保克等咪唑类药剂对大蒜叶枯病有较好的治疗效果〔2〕。1999年10月至2000年3月笔者对瑞士诺华公司最新研制的三唑类药剂10%世高水分散粒剂进行了防治大蒜叶枯病的田间试验，现将结果小结如下。1 材料与方法1.1 供试药剂 10%世高水分散粒剂(有效成分Score，瑞士诺华公司)，25%施保克乳油(有效成分P…     

Induction of protective immune responses against challenge of Actinobacillus pleuropneumoniae by oral administration with Saccharomyces cerevisiae expressing Apx toxins in pigs

Actinobacillus pleuropneumoniae is a causative agent of porcine pleuropneumonia, a highly contagious endemic disease of pigs worldwide, inducing significant economic losses worldwide. Apx toxins, which are correlated with the virulence of A. pleuropneumoniae, were expressed in Saccharomyces cerevisiae and its possible use as an oral vaccine has been confirmed in our previous studies using a murine model. The present study was undertaken to test the hypothesis that oral immunization using S. cerevisiae expressing either ApxI or ApxII could protect pigs against A. pleuropneumoniae as an effective way of inducing both mucosal and systemic immune responses. The surface-displayed ApxIIA#5 expressing S. cerevisiae was selected as an oral vaccine candidate by finding on induction of higher immune responses in mice after oral vaccination. The surface-displayed ApxIIA#5 expressing S. cerevisiae and the ApxIA expressing S. cerevisiae were developed to serve as an oral vaccine in pigs. The vaccinated pigs showed higher specific IgG- and IgA-related antibody activities than the non-treated control and vector control pigs. Additionally, the induced immune responses were found to protect pigs infected with A. pleuropneumoniae according to the analysis of clinical signs and the gross and microscopic pulmonary lesions. These results suggested that the surface-displayed ApxIIA#5 and ApxIA in S. cerevisiae might be a potential oral vaccine to protect pigs against porcine pleuropneumonia. Thus the present study is expected to contribute to the development of a live oral vaccine against porcine pleuropneumonia as an alternative to current conventional vaccines.     

Effects of short-term sodium chlorate exposure on pigs

The present study evaluated the effects of exposure to different doses of sodium chlorate in 10-week-old pigs. Twenty pigs were divided into four equal groups and treated with different doses of sodium chlorate: 0, 125, 250 and 500 mg kg-1 body weight per day via the drinking water for 7 consecutive days. The results showed a significant decrease (P < 0.05) in red blood cell and white blood cell counts, packed cell volume, haemoglobin, blood urea nitrogen (P < 0.001) and creatinine levels, and an increase in aspartate aminotransferase and alanine aminotransferase (P < 0.05) activities in swine administered sodium chlorate at a dose of 500 mg kg-1 body weight per day. The histopathological study revealed increased numbers of vacuoles in the convoluted tubules, tubular necrosis and degeneration of the renal tubular epithelial cells, depletion of nuclei and lobular necrosis of the liver in all pigs treated with sodium chlorate at 500 mg kg-1 body weight per day. Thus, 7-day administration of sodium chlorate at 500 mg kg-1 body weight per day to pigs affects the liver and kidney tissues as well as the haematologic and serum biochemical parameters.