Some remarks concerning kissing numbers,blocking numbers and covering numbers

This article shows an inequality concerning blocking numbers and Hadwiger's covering numbers and presents a strange phenomenon concerning kissing numbers and blocking numbers. As a simple corollary, we can improve the known upper bounds for Hadwiger's covering numbers ford-dimensional centrally symmetric convex bodies to 3 ^d –1.     

IRIS/AP-ICP-AES法同时测定地表水中的Cu、Pb、 Zn、Mn和Cd

采用铜试剂富集和IRIS／AP－ICP－AES法同时测定地表水中的Cu、Pb、Zn、Mn和Cd。优选出最佳仪器工作条件和被测元素分析谱线。讨论了水样中主量元素的干扰，实验结果表明本法精密度高，检出限低，回收效果好，结果准确，适用于地表水的日常监测。     

纳米载体固定化酶的最新研究进展

催化剂是化学工业的重要基础,其中酶是重要的高效天然催化剂。近年来,酶被越来越多地应用于工业领域,如精细化工、食品工业、制药工业、纺织业和制浆造纸。然而,由于游离酶存在价格昂贵及操作稳定性(特别是回收与重复使用性能)低等缺点,其在工业上的进一步应用受到一定限制。对酶进行固定化是解决上述问题的有效途径。一个理想的酶固定化技术需要载体具有良好的生物相容性和高比表面积,能够负载适量的酶并且具有很好的重复使用性能,固定化酶的过程简单温和,所得到的固定化酶制剂具有良好的催化性能、稳定性以及工业应用价值。尽管固定化酶技术经过了多年的发展,但仍需进一步研究。近几年,人们研究了基于纤维素纳米晶类、聚多巴胺类纳米载体以及生物相容性合成有机物纳米胶等新型载体对酶的固定化,取得了较好的成果。本文综述了这些新型纳米载体的制备以及酶的固定化过程,阐述了纳米载体固定化酶的结构和催化性能,并展望了发展前景。纤维素是全球产量最高、来源最广的生物聚合物。纤维素经过一定的酸(常用硫酸和盐酸)水解处理后,剩下的是具有高结晶度的纤维素纳米晶。它具有高比表面积、高机械强度和高长径比等优异性能。因此,研究者利用纤维素纳米晶作为载体进行酶固定化,获得了高负载量、高催化性能的固定化酶制剂。基于仿生矿化法制备的聚多巴胺类材料近年来获得研究者越来越多的关注。多巴胺具有良好的自聚合能力,可以对无机、有机等各种材料进行表面修饰。同时,聚多巴胺中含有的活性官能团可以与酶发生交联,从而达到固定化酶的效果。基于合成性聚合物纳米胶载体的固定化酶技术同样是一个新兴的、有意义的研究领域。相关的固定化过程可分为两大类：(1)在酶分子表面通过原位聚合生成纳米胶(growing-from过程);(2)将酶与预先合成的纳米胶进行交联(grafting-to过程)。其中, growing-from过程是先将酶分子丙烯酰化,再进行原位聚合。而原位聚合又可分为自由基聚合、原子转移自由基聚合(ATRP)和可逆加成-断裂链转移聚合(RAFT)。其中, ATRP和 RAFT主要用于制备环境响应型的酶-聚合物纳米凝胶。     

Design,Synthesis, and Biological Screening of Novel Anthranilic Diamides

Three series of new anthranilic diamide derivatives containing sulfide, N‐cyanomethylsulfilimine, and N‐cyanomethylsulfoximine groups were designed and synthesized by combining the active substructures of anthranilic diamides and sulfoxaflor. The structures of all newly synthesized compounds were confirmed by IR and ¹H/¹³C‐NMR, and some of them were confirmed by elemental analysis or HRMS too. The synthesized compounds were screened for their insecticidal and fungicidal activities. Bioasssay results indicated that some of the synthesized compounds possessed certain degrees of insecticidal activity against Mythimna separata. However, some compounds exhibited good fungicidal activity against Sclerotinia sclerotiorum.     

The Translative Kissing Number of Cartesian Product of two Convex Bodies, one of which is Two-Dimensional

This article discusses the relation between the translative kissing numbers of convex bodies K ₁, K ₂ and K ₁ K ₂. As an application of the main theorem, we find that the translative kissing number of B Q, where B is a 24-dimensional ball and Q is a two-dimensional non-parallelogram convex domain, is 1375926.     

The strongly irreducible operators in nest algebras

An operatorT on is called strongly irreducible ifT does not commute with any nontrivial idempotent operator. In this paper, we first show that each nest algebra ( ) has strongly irreducible operators. Secondly, we obtain a characterization of operators which can be uniquely written as a direct sum of finitely many strongly irreducible operators. Finally, we characterize the strongly irreducibility of operators in a nest algebra ( ).This project was partially supported by National Natural Science Foundation of China.     

相转移催化羰基化合成丙二酸二乙酯的研究

在相转移催化剂存在下，使用原位制备的钴催化剂实现了氯乙酸乙酯的常压羰基化，丙二酸二乙酯收率达８０％以上。讨论了溶剂、相转移催化剂等对反应的影响。     

马来酸酐—醋酸乙烯酯梳状聚合物单阳离子导体的制备及表征

马来酸酐－醋酸乙烯酯交替共聚物以聚乙二醇单醚醇解，得到带有不同长度的聚醚氧侧链的羧酸型梳状聚合物，其碱金属盐在加入适当增塑剂成膜后，可作为聚合物单阳离子导体，其结构以非晶态为主，具有较低的玻璃化转变温度及较好的热稳定性，增塑后的室温电导率最高可达１０－５Ｓ／ｃｍ．研究发现，适当增加侧链的长度有利于提高聚合物膜的离子电导率．此外，还详细探讨了增塑剂、阳离子半径、温度及外加频率等因素对电导率的影响．     

LiCoO2的固相配位化学合成

目前商品化的锂离子电池大都采用ＬｉＣｏＯ2作为正极材料[1],工业上锂钴氧化物(ＬｉＣｏＯ2)多采用高温固相合成法生产,烧结时间长达24-48ｈ,制得的粉末粒度大分布范围广,形貌不规整[2]。溶胶 凝胶法前驱体的制备比较麻烦[3]。我们用固相配位化学反应法合成锂钴氧化物Ｌｉ ＣｏＯ2,操作简便兼具反应温度低、反应时间短、粒度分布均匀的优点[4,5]。本文采用氢氧化锂、乙酸钴和柠檬酸为原料,通过低热固相反应合成了Ｌｉ+与Ｃｏ2+达到分子级混合水平的前驱体、在400-800℃焙烧得ＬｉＣｏＯ2产品,通过热重/差热、Ｘ射线衍射、扫描电镜和粒…     

Traceless liquid-phase synthesis of 3-alkylamino-4,5-disubstituted-1,2,4-triazoles on polyethylene glycol (PEG)

A liquid-phase route to 3-alkylamino-4,5-disubstituted-1,2,4-triazoles has been developed, which permits the incorporation of three elements of diversity. The heterocycle was constructed upon PEG6000 (soluble polymer) modified by 4-hydroxy-2-methoxybenzaldehyde, from which a traceless cleavage could be realized with TFA/CH₂Cl₂. This method provided a library of 3-alkylamino-4,5-disubstituted-1,2,4-triazoles with reasonable yields and excellent purity.