次氯酸光照分解实验研究

现行高中化学课本中的次氯酸光照分解实验,装置复杂,光照长,分解速度慢,产生的氧气少,难于检查,笔者从改进装置着手,对影响本实验的因素作了研究。改进后的装置简单,现象明显,适合课堂演示。     

Increased mitochondrial palmitoylcarnitine/carnitine countertransport by flavone causes oxidative stress and apoptosis in colon cancer cells

Cancer cell metabolism is characterized by limited oxidative phosphorylation in order to minimize oxidative stress. We have previously shown that the flavonoid flavone in HT-29 colon cancer cells increases the uptake of pyruvate or lactate into mitochondria, which is followed by an increase in O₂^−.. production that finally leads to apoptosis. Similarly, a supply of palmitoylcarnitine in combination with carnitine induces apoptosis in HT-29 cells by increasing the mitochondrial respiration rate. Here we show that flavone-induced apoptosis is increased more than twofold in the presence of palmitoylcarnitine due to increased mitochondrial fatty acid transport and the subsequent metabolic generation of O₂^−. in mitochondria is the initiating factor for the execution of apoptosis. Received 12 August 2005; received after revision 12 October 2005; accepted 14 October 2005     

外源视黄酸对小鼠早期胚胎形态及Otx2基因表达的影响

以全反式视黄酸（ａｌｌｔｒａｎｓ－ｒｅｔｉｎｏｉｃａｃｉｄ，ＲＡ）体外处理ＥＢ（ｅａｒｌｙａｌｌａｎｔｏｉｃｂｕｄ）期和ＬＢ（Ｌａｔｅａｌｌａｎｔｏｉｃａｃｉｄ）期的小鼠胚胎，然后用洋地黄毒苷（ｄｉｇｏｘｉｇｅｎｉｎ）标记的Ｏｔｘ２反意义ＲＮＡ探针对整体胚胎进行原位杂交．０．５×１０－６ｍｏｌ～２×１０－６ｍｏｌ的ＲＡ处理ＥＢ和ＬＢ期胚胎１２ｈ后对其形态学和Ｏｔｘ２表达都没有影响；以４×１０－６ｍｏｌ的ＲＡ处理，抑制或减少了胚胎的前肠形成，经处理的胚胎的头褶没有对照的那样明显向腹面突出，其神经沟也不整齐；以４×１０－６ｍｏｌ的ＲＡ处理ＥＢ期的胚胎，其ＯｔＸ２表达范围剧烈地向前退缩或只有很微弱的表达；但以同样浓度处理ＬＢ期胚胎时，与对照胚胎相比，ＯｔＸ２的表达除了在极少数胚胎中变得弱一些外，在绝大多数胚胎中其表达模式没有变化．     

桉木抽出物的主要化学组成及结构类型的初步研究

采用化学分析和光谱和分析相结合的方法，对不同树种和树龄桉木抽出物的主要化学组成及结构类型进行初步研究，结果表明：桉木出物主要集中于心材；树龄越大，抽出物越多；幼龄材的抽出物较少，适宜于制浆造纸桉木的颜色主要是由多酚类化合物引起的。存放过久的桉木中的抽出物大变成黄粉，既不溶于水，也不溶于丙酮，只溶于稀碱或亚硫酸钠。在制浆前采用稀碱或亚硫酸钠预处理桉木是必要的。桉木多酚类化合物以水单宁为主，属鞣花酚类     

A pyruvate kinase variant in different mouse transplanted tumors

Summary Mouse transplanted tumors, in contrast to normal tissues, contain a pyruvate kinase (PK) variant sensitive to the inhibitory action of L-cysteine and less sensitive to saturated fatty acids than the normal enzyme. In selected normal and tumor materials two fractions of PK were separated. Fraction A (20–30% (NH₄)₂SO₄ saturation) dominated in normal liver, and fraction B (50–60% (NH₄)₂SO₄ saturation) in skeletal muscles and Ehrlich ascites tumor. Only this fraction B from tumor material was sensitive to L-cysteine, and seems to contain a tumor-specific PK variant which might be considered as a marker of neoplastic transformation in a broad spectrum of mouse experimental tumors.     

ZnL2Cl4的晶体结构、荧光性质及标准摩尔反应焓变

在无水乙醇中,用1-氨基-4-甲基哌嗪缩水杨醛（L）与ZnCl2合成了希夫碱配合物ZnL2Cl4,对其进行了元素分析及固体荧光袁征,并用Xn射线衍射测定了其单晶结构．结果表明,Zn^2＋与4个Cl-形成配位键,并与配体以分子间氢键形式联接成三维超分子结构．晶体属于单斜晶系,空间群为C2／c,晶胞参数α=12．0757（12）nm,b-8．9859（8）nm,c-27．435（3）nm,β=98．9450（10）°,V=2940．8（5）nm3,Z=4,F（000）=1344,Dc=1．463g／cm3,μ=1．231mm^-1．该L及ZnL2Ck均有较好的发光性质,发出蓝色荧光．298．15K下,ZnCl2和L在无水乙醇中的溶解焓及配合物液相反应生成焓分别为（7．150±0．022）,（-32．587±0．307）,（3．745±0．035）kJ／tool,热化学循环求得固相标准摩尔反应焓变为（-54．279±0．671）kJ／m01．     

竹炭基固体酸加压催化高酸值油脂的降酸效果

 选取4年生的慈竹和浓硫酸为原料制备竹炭基固体酸催化剂,考察用该催化剂催化油酸和甲醇酯化反应,以模拟高酸值油脂的酯化降酸效果,并研究了醇油比、催化剂用量、反应温度、反应时间及重复利用性等因素对转化率的影响.通过单因素试验确定甲醇和油酸体积比为1∶1,催化剂用量为2%,反应温度为120 ℃,反应时间为4 h的条件下,其油酸转化率为94.70%,通过和无催化剂对照试验对比,油酸转化率提高50%,催化剂重复使用到第5次时,油酸转化率仍可达到72.47%.