α-氨基丁酸对映异构体在DMF+水混合溶剂中的焓对作用

利用等温滴定微量热法(ITC)分别测定了298.15K时L-α-氨基丁酸和D-α-氨基丁酸两种对映异构体在不同组成的二甲基甲酰胺(DMF)+水混合溶剂中的稀释焓.根据统计热力学的McMillan-Mayer理论计算各溶剂组成下的同系焓对作用系数(hxx).从溶质-溶质和溶质-溶剂相互作用的观点出发探讨了三元水溶液中疏水-疏水、疏水-亲水和亲水-亲水作用的竞争平衡.实验发现,在所研究的混合溶剂组成范围内(wDMF=0-0.3),α-氨基丁酸两种对映体的hxx都是较大的正值,且都随wDMF的增大而逐渐减小,而有趣的是L型对映体的hxx值普遍比D型的大(hLLhDD),说明ITC可以区分对映异构体的同手性焓对作用.结果表明:在α-氨基丁酸+水+DMF三元溶液体系中,疏水-疏水和疏水-亲水作用在分子对作用过程中占优势;在α-氨基丁酸的同种对映体发生分子对作用时,L-L分子对比D-D分子对在构型上更有利于α-碳上疏水侧链(CH3CH2-)的靠拢,疏水基团的水合壳层发生交盖,局部破坏而释放出部分结构化的水,过程自发、吸热且伴随显著熵增(ΔG0,ΔH0,ΔS=(ΔH-ΔG)/T0),因而在稀释时释放出更多热量,hxx具有较大的正值.     

Surfactant-assisted hollowing of Cu nanoparticles involving halide-induced corrosion-oxidation processes

We have demonstrated a simple fabrication of hollow nanoparticles by halide-induced corrosion oxidation with the aid of surfactants. Cuprous oxide Cu2O nanoshells can be generated by simply mixing Cu nanoparticles with alkyltrimethylammonium halides at 55 degrees C for 16 min. The hollowing mechanism proposed is that absorption of surfactants onto the Cu surface facilitates the formation of the void interior through an oxidative etching process. Upon extending the reaction up to 4 h, fragmentation, oxidation, and self-assembly were observed and the CuO ellipsoidal structures were formed. The headgroup lengths of the surfactants influenced the degree of CuO ellipsoidal formation, whereby longer surfactants favored the generation of ellipsoids. Optical absorption measured by UV-visible spectroscopy was used to monitor both oxidation courses of Cu-->Cu2O and Cu2O-->CuO and to determine the band-gap energies as 2.4 eV for Cu2O nanoshells and 1.89 eV for CuO ellipsoids. For the contact-angle measurements, the wettability changed from hydrophilicity (18 degrees) to hydrophobicity (140 degrees) as the Cu2O nanoshells shifted to CuO ellipsoids.     

Comparison of the applicability of rule-based and self-organizing fuzzy logic controllers for sedation control of intracranial pressure pattern in a neurosurgical intensive care unit

This paper assesses the controller performance of a self-organizing fuzzy logic controller (SOFLC) in comparison with a routine clinical rule-base controller (RBC) for sedation control of intracranial pressure (ICP) pattern. Eleven patients with severe head injury undergoing different neurosurgeries in a neurosurgical intensive care unit (NICU) were divided into two groups. In all cases the sedation control periods lasted 1 h and assessments of propofol infusion rates were made at a frequency of once per 30 s. In the control group of 10 cases selected from 5 patients, a RBC was used, and in the experimental group of 10 cases selected from 6 patients, a self-organizing fuzzy logic controller was used. A SOFLC was derived from a fuzzy logic controller and allowed to generate new rules via self-learning beyond the initial fuzzy rule-base obtained from experts (i.e., neurosurgeons). The performance of the controllers was analyzed using the ICP pattern of sedation for 1 h of control. The results show that a SOFLC can provide a more stable ICP pattern by administering more propofol and changing the rate of delivery more often when rule-base modifications have been considered.     

X射线烧蚀泡沫-固体靶增压机理研究

X射线烧蚀泡沫-固体靶时界面失配会使得泡沫与固体靶中压力增加, 这一现象可用于研究高压下物质的状态方程. 本文以CH泡沫-Al固体靶为例, 研究了X射线烧蚀双层靶时的增压现象. 提出仅当泡沫中有冲击波产生时, 在固体靶中才会有增压现象出现. 文中基于冲击波强波近似, 理论分析了冲击波过界面情况与冲击波、稀疏波作用过程, 得到增压倍数与材料密度, 多方气体指数的近似表达式. 同时表明固体靶中增压产生的冲击波为高压脉冲, 会被紧跟热波的稀疏波追赶并稀疏. MULTI一维计算结果验证了该结论.     

ICF实验软X射线能谱仪对辐射能流时间关联测量的时标系统

介绍了时标系统的构成、原理和数据处理方法,并对时间关联的不确定度进行了分析.该时标系统成功将软X射线能谱仪 自身多个探测通道的信号以及三台不同位置处的谱仪的时间信号关联起来,关联精度约为70 ps.在神光III原型激光装置上进行的实验中用软X射线能谱仪从不同方向测得辐射源和辐射输运管末端口辐射能流随时间的演化曲线,反映了输运管内热波沿轴向传输以及软X射线辐射流衰减的物理过程.     

A non-selenization technology by co-sputtering deposition for solar cell applications

This work presents a novel method to form polycrystalline Cu(In(1-x)Ga(x))Se(2) (CIGS) thin film by co-sputtering of In─Se and Cu─Ga alloy targets without an additional selenization process. An attempt was also made to thoroughly elucidate the surface morphology, crystalline phases, physical properties, and chemical properties of the CIGS films by using material analysis methods. Experimental results indicate that CIGS thin films featured densely packed grains and chalcopyrite phase peaks of (112), (220), (204), (312), and (116). Raman spectroscopy analysis revealed chalcopyrite CIGS phase with Raman shift at 175 cm(-1), while no signal at 258 cm(-1) indicated the exclusion of Cu(2-x)Se phase. Hall effect measurements confirmed the polycrystalline Cu(In,Ga)Se₂ thin film to be of p type semiconductor with a film resistivity and mobility of 2.19×10(2) Ω cm and 88 cm(2)/V s, respectively.     

Adlay Seed (Coix lacryma-jobi L. var. Ma-yuen Stapf.) Ethanolic Extract Fractions and Subfractions Induce Cell Cycle Arrest and Apoptosis in Human Breast and Cervical Cancer Cell Lines

The antitumor effects of Coix lacryma-jobi L. var. ma-yuen Stapf. (adlay seed) ethanolic extract have been increasingly shown. This study aimed to investigate the beneficial effects of both the fractions and subfractions of adlay seed ethanolic extract on the human breast (MCF-7) and cervical (HeLa) cancer cell lines, as well as exploring their possible mechanisms of action. The ethanolic extracts were obtained from different parts of adlay seed, including AHE (adlay hull extract), ATE (adlay testa extract), ABE (adlay bran extract) and PAE (polished adlay extract). The results of a 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl- tetrazolium bromide (MTT) assay showed that AHE-Ea and ATE-Ea showed significant growth inhibitory effects in a dose-dependent manner. The results also showed that the AHE-Ea-K, AHE-Ea-L, ATE-Ea-E and ATE-Ea-F subfractions inhibited cell proliferation, induced cell cycle arrest in the G0/G1 phase and decreased CDK4/Cyclin D1 protein expression. Finally, the extract activated caspase-3 activity and PARP protein expression, which induced MCF-7 and HeLa cell apoptosis. We then used liquid chromatography–mass spectrometry (LC/MS) to identify the potential active components., Quercetin showed an anticancer capacity. In conclusion, the AHE-Ea-K, AHE-Ea-L, ATE-Ea-E and ATE-Ea-F subfractions showed antitumor effects through the inhibition of MCF-7 and HeLa cell line viability, as well as inducing apoptosis and cell cycle arrest.     

FETCH: A cloud-native searchable encryption scheme enabling efficient pattern search on encrypted data within cloud services

Searchable encryption (SE) is considered important as it provides both confidentiality and searchability for the data stored in semi-trusted environments such as cloud. However, it is rarely deployed because most SE schemes are not native to cloud services as they require database modifications. In this paper, we present an SE scheme called Frequency-Eliminated Trapdoor-Character Hopping (FETCH) that, based on novel common-conditioned-subsequence-preserving (CCSP) techniques, is able to work natively with off-the-shelf databases and supports wildcard-based pattern search on encrypted data thereof. In fact, with the CCSP techniques, we transform the problem of wildcard SE searching into a problem of subsequence searching, which is solved fast in most databases and thus fits well with cloud services in general. Although in our security analysis, CCSP removes the possibility of obtaining theoretical indistinguishability between indexed items, we show that FETCH does provide adequate confidentiality protection and fares much better than other existing wildcard SE schemes in terms of query performance, storage overhead, and deployment complexity. In particular, FETCH is able to efficiently handle data sets whose size is multiple orders of magnitude larger than those that existing schemes can comfortably support.     

Structure–property relationship of dipyridyl−Cu polymers containing inorganic clusters Te/SeFe3(CO)9

This mini-review covers a novel series of 1D and 2D Te/SeFe₃(CO)₉-incorporated (Te, 1a ; Se, 1b ) Cu-based coordination polymers synthesized by the liquid-assisted grinding (LAG) method using predesigned compound [TeFe₃(CO)₉Cu₂(MeCN)₂] ( 1a-Cu ₂ (MeCN) ₂ ) with rigid or flexible dipyridyl ligands, or three components of [SeFe₃(CO)₉]²⁻ ( 1b ), [Cu(MeCN)₄]⁺, and dipyridyls. These polymers displayed various cluster coordination modes, including cluster-blocked [EFe₃(CO)₉Cu₂(L)]_n (E = Te, 1a-L-1D , Se, 1b-L-1D ; L = 1,2-bis(4-pyridyl)ethylene (bpee), 1,2-bis(4-pyridyl)ethane (bpea)), cluster-pendant [SeFe₃(CO)₉Cu₂(dpy)₃]_n ( 1b-dpy-1D , dpy = 4,4′-dipyridyl) and [EFe₃(CO)₉Cu₂(L)_2.5]_n (E = Te, 1a-L-2D , Se, 1b-L-2D ; L = bpee, bpea), cluster-linked [SeFe₃(CO)₉Cu₂(MeCN)(dpy)_1.5]_n ( 1b-dpy-2D ) and [SeFe₃(CO)₉Cu₂(bpp)₂]_n ( 1b-bpp-2D , bpp = 1,3-bis(4-pyridyl)propane), as well as the unique cation-anion polymer [{Cu₂(bpp)₄}{(TeFe₃(CO)₉Cu)₂(bpp)}]_n ( 1a-bpp-CA ). Their dimensionality expansions and reversible transformations accompanied with bonding pattern changes were achieved upon the addition of stoichiometric amounts of appropriate agents. These polymers exhibited pronounced semiconducting properties with tunable energy gaps and optical (dc) or electrical conductivities. The trend of their semiconductivities can be related to bonding patterns, where efficient electron communications were proved to stem from the existence of carbonyl ligands and electron-rich clusters 1a and 1b . In particular, water−/light-stable 1b -based polymers exhibited excellent photodegradation activities toward nitroaromatics and organic dyes, where the efficiency was further rationalized by their structural features and narrow energy gaps.