"十二五"期间广西酸雨污染变化特征分析

为了解"十二五"期间广西酸雨污染特征及变化趋势情况,利用"十二五"期间广西全区14个市的大气降水监测数据,通过pH值、酸雨频率、降水离子组分3方面数据统计并分析其变化趋势。"十二五"期间广西酸雨污染主要为弱酸性酸雨,其次为酸性酸雨,重酸性酸雨污染占比不足20%,较少有严重酸性酸雨;降水酸度总体呈减弱趋势,酸雨频率呈波动下降趋势,5年期间城市酸雨污染整体呈减轻趋势;酸雨区域主要集中在桂北、桂西部地区,东南部由酸雨区域变为非酸雨区域,酸雨区域面积有所减少;降水中SO24-离子当量浓度逐年下降,NO3-离子当量浓度呈上升趋势,SO24-/NO3-的比值呈现显著下降趋势,广西酸雨污染特征由硫酸型向硫酸与硝酸混合型酸雨过渡。广西的酸雨污染略有减轻趋势,这与广西近年来的环境治理取得的成效有关。     

冬季海水养殖水域环境因子的变化对养殖海参的影响研究

2016年和2017年两个结冰期内对渤海某海水人工养殖池塘冰厚度的变化和冰盖下水体的温度、盐度、p H和溶解氧进行连续观测。冰厚采用超声测距仪定时测量,冰温、水温、盐度、溶解氧和p H分层观测。研究发现,盐度的变化与冰的生长密切相关,而冰厚度的变化主要受气温的控制,p H和溶解氧的变化与水温和光合作用相关,冰融化时p H和溶解氧变化浮动较大,冰融水起到了稀释作用,溶解氧浓度降低。可见,气温影响冰厚和水温,进而间接影响了盐度、p H和溶解氧。观测的养殖池塘水体溶氧含量一直大于8 mg·L-1,没有出现缺氧的情况。p H范围在7. 7～9. 0之间,没有出现异常。养殖池塘内的海参对盐度的耐受范围是20～35,而其栖息的水体底层的盐度,主要是在29. 022 7～34. 028 6间,仅当冰融化时,盐度最低值降到21. 074 8,但在之后再3～5 d内上升至29,可见,盐度的变化是在其可承受范围内。综上分析,温度是决定冬季海水养殖生物存活率的限制因素。     

P型和N型Cu_2O薄膜的电化学制备

以FTO玻片为基底,在不同pH值下采用恒电位电化学沉积法制备Cu2O样品.利用XRD、SEM、EDS对样品的相组成、晶体结构、微观形貌和化学成分进行了表征,并对Cu2O薄膜的光电性质和载流子类型进行了测量和分析.结果表明Cu2O薄膜的半导体性质与所用电解液的酸碱度有关,在酸性条件下,如pH=4,5时制备的Cu2O薄膜为N型半导体,在中性和碱性条件下,如pH=6,7,8,9,10,11时,制备的Cu2O薄膜为P型半导体.实验结果对制备N型Cu2O以及Cu2O的PN型同质结提供了一种有效方法.     

pH-Compensation Effect of Lysine on the Acidic Degradation of Electrospun Poly（ lactide-co-glycolide） Fibers in PBS

Electrospun aligned ultrafine fibers of poly（ lactide-coglycolide）（ PLGA） can be used to construct biomimetic scaffolds for engineering those structurally anisotropic and dense tissues（ e. g.,tendon,ligament,etc.）. But the acidic degradation products of the PLGA could result in p H decrease in the vicinity of the scaffolds,which may give rise to biocompatibility concerns. To address the noted problem, this study was designed to evaluate the p Hcompensation capacity of using Lysine（ Lys） —a kind of basic amino acid on the acidic degradation products of PLGA. Ultrafine PLGA（ 50∶ 50） fibers with 0,10%,20%,and 30% by weight of Lys loadings were prepared by a stable jet electrospinning（ SJES）approach. The morphology,structure,and mechanical properties of the electrospun aligned fibrous mats of Lys-incorporated PLGA（ 50∶50） were characterized by scanning electron microscope（ SEM）,Fourier transform infrared spectroscopy（ FTIR）,and tensile testing,respectively. Thereafter,the fibrous PLGA（ 50 ∶50） scaffolds were subjected to degradation by being immersed in phosphate buffered saline（ PBS,p H 6. 86） solution at 37 ℃ for 5weeks. Our results show that the formed Lys / PLGA composite ultrafine fibers have a well-aligned and uniform morphology with a fineness of ca. 1 #m in diameter. Introduction of Lys led to increased mechanical performance; that is,when the Lys loading is less than 30%,tensile strength and Young＇s modulus of the aligned Lys / PLGA fibers reached up to the impressive values of 84. 5 MPa and 2. 4 GPa,respectively. Degradation results show that the p H of the PLGA group fell to 5. 6 in 5 weeks while the p H of the Lys /PLGA groups with 10%,20%, and 30% of Lys loadings was maintained at 6. 3, 6. 5 and 6. 7, respectively. This work demonstrated that incorporation of Lys into electrospun PLGA fibers could be an effective approach in mediating the p H decrease caused by the acidic degradation products of the PLGA.     

KBrO_3-Na_2SO_3-K_4Fe(CN)_6体系pH振荡影响因素研究

研究影响KBrO3-Na2SO3-K4Fe(CN)6(BSF)体系pH振荡行为的各种因素。通过测试BSF体系在封闭条件下和在连续流动搅拌反应器(CSTR)中反应的pH-时间曲线,考察温度、流速、酸度、搅拌速率等因素对BSF体系pH振荡行为的影响。测得振荡反应的正反馈、负反馈及周期的表观活化能分别为57.21 kJ/mol、78.63 kJ/mol和32.08 kJ/mol。在CSTR条件下,温度、流速、酸度、搅拌速率等皆对振幅和周期有较明显的影响,且在一定范围内皆与周期和振幅的变化存在一定的线性关系。该研究建立了多因素与振荡行为之间的规律,对于研究其他振荡体系有一定的参考价值,同时为以pH振荡为刺激源的智能材料选择适当的振荡条件提供了理论依据。     

壳聚糖固定化云芝漆酶的制备及特性

以壳聚糖为载体,戊二醛为交联剂制备固定化漆酶,测定了不同戊二醛浓度、交联时间、给酶量以及固定化时间对固定化漆酶活性的影响.结果表明,固定化反应的最佳条件为戊二醛浓度5%,交联时间8 h,给酶量20 mg/g载体,固定化时间6 h,在此条件下制备的固定化漆酶酶活性保持率为52.2%.此固定化漆酶具有最大活性时的溶液pH值在4.5,相比于自由漆酶的最佳pH值5.0,其向酸性偏移;与自由漆酶相比,固定化酶有很好的稳定性和可重复使用性.     

In fl uence of HEPES buffer on the local pH and formation of surface layer during in vitro degradation tests of magnesium in DMEM

The human body is a buffered environment where p H is effectively maintained. HEPES is a biological buffer often used to mimic the buffering activity of the body in in vitro studies on the degradation behavior of magnesium. However, the influence of HEPES on the degradation behavior of magnesium in the DMEM pseudo-physiological solution has not yet been determined. The research aimed at elucidating the degradation mechanisms of magnesium in DMEM with and without HEPES. The morphologies and compositions of surface layers formed during in vitro degradation tests for 15–3600 s were characterized. The effect of HEPES on the electrochemical behavior and corrosion tendency was determined by performing electrochemical tests. HEPES indeed retained the local p H, leading to intense intergranular/interparticle corrosion of magnesium made from powder and an increased degradation rate. This was attributed to an interconnected network of cracks formed at the original powder particle boundaries and grain boundaries in the surface layer, which provided pathways for the corrosive medium to interact continuously with the internal surfaces and promoted further dissolution. Surface analysis revealed significantly reduced amounts of precipitated calcium phosphates due to the buffering activity of HEPES so that magnesium became less well protected in the buffered environment.     

河南省三门峡市大气降水酸碱度变化分析及对策探讨

利用三门峡市2007—2011年5年酸雨测量资料及其他有关资料,采用气候倾向率、加权平均法等统计学方法,分析了三门峡市大气降水酸碱度的变化特征及酸雨与降水量、风速、风向、云状、雾等气象条件的关系,并对酸雨影响因素进行分析.结果表明:近5年三门峡市降水的平均pH值为5.2;pH5.6的酸性降水出现比率为57.2%;采暖期的11月—3月pH值较低,平均为5.10,其中12月最低,只有4.39,达到了4.5≤pH5.6的弱酸性降水标准;非采暖期的4月—10月pH值较高,平均为5.21,其中6月份最高为6.13.根据分析结果,提出相应的对策.     

针型复合钨/氧化钨微型pH复合电极的研制及应用

利用自制的钨/氧化钨为p H指示电极,以Ag/Ag Cl电极为参比电极,组装于不锈钢针头内,制成针型钨/氧化钨微型p H复合传感器.该复合p H电极对H+的响应范围为p H=2.0~11.0,能斯特响应斜率为-53.83 m V/p H,响应时间小于1 min.该电极具有机械强度高、响应快、重现性好、制作简单等优点,并已应用于水果原位微区测量,具有较好的效果.     

对皖北地区白酒曲粉中酵母菌的分离筛选

本研究针对皖北地区某酿酒企业提供的中温大曲进行了分离、纯化,采用涂布法、划线法对微生物菌群进行恒温培养并对其中的酵母菌进行形态学和生理学的测定后,得到两株酵母菌F1与F2。将得到的菌株F1、F2转接至液体发酵瓶中摇床培养,在此发酵周期中提取发酵液进行各项生化指标的测定,数据分析后得知F1酵母菌的适宜生长p H范围为4.0~6.0,F2酵母菌在发酵过程中p H值呈现上升趋势;在发酵第3d时,两种酵母菌发酵液中残糖含量开始迅速减少,在实际生产过程中则需要及时填补料液以保证发酵过程的顺利进行,该研究为企业生产提供了有效的数据支撑,具有一定的现实指导意义。