nBu4NI-catalyzed oxidative amidation of aldehydes with tertiary amines

An efficient oxidative coupling protocol for amide formation has been developed. Various tertiary amines and aromatic aldehydes were oxidized to their corresponding tertiary amides in moderate to good yields in the presence of a simple nBu₄NI-catalyst.     

Tunable nano Peltier cooling device from geometric effects using a single graphene nanoribbon

Based on the phenomenon of curvature-induced doping in graphene we propose a class of Peltier cooling devices, produced by geometrical effects, without gating. We show how a graphene nanorib- bon laid on an array of curved nano cylinders can be used to create a targeted and tunable cooling device. Using two different approaches, the Nonequilibrium Green＇s Function （NEGF） method and experimental inputs, we predict that the cooling kW/cm2, on par with the best known techniques power of such a device can approach the order of using standard superlattice structures. The structure proposed here helps pave the way toward designing graphene electronics which use geometry rather than gating to control devices.     

Simple spectrophotometric assessment of the trans-/cis-resveratrol ratio in aqueous solutions

The solubility and molar absorptivity of trans- and cis-resveratrol isomers in aqueous solvents are poorly described. This study aimed to develop and describe a new simple method for the determination of trans- and cis-resveratrol concentrations in aqueous solutions. Up to 300 μM trans-resveratrol was dissolved in water by sonication for 2 h. Cis-resveratrol was obtained by exposing a 100-μM trans-resveratrol aqueous solution to sunlight for 8 h, followed by HPLC separation and analysis by mass spectrometry (resveratrol oxidation products were absent). Accurate values for UV absorbance in water were ελmax=ε304 nm=30 335 M−1 cm−1, ?_286 nm = 23 400 M⁻¹ cm⁻¹ for trans-resveratrol and ελmax=ε286 nm=14 986 M−1 cm−1, ?_304 nm = 9515 M⁻¹ cm⁻¹ for cis-resveratrol. These values allowed us to propose formulae to assess the trans-/cis-resveratrol ratio in water, using a simple and reliable UV-vis spectrophotometric method. Statistical analysis revealed no significant difference between our UV method and the commonly used HPLC method. All these data are transferable to 150 mM NaCl and 10 mM phosphate buffer solutions, which could be particularly useful for cell culture, ex vivo and in vivo studies.     

Transition metal free oxidative esterification of alcohols with toluene

Using Bu₄NI as the catalyst and tert-butyl hydroperoxide as the oxidant, direct esterification of alcohols with toluene derivatives was achieved. Mechanistic investigations indicate that the alcohols are sequentially oxidized to aldehydes, carboxylic acids, and then to benzyl esters. Bu₄N⁺ functions as a phasetransfer reagent and iodide catalyzes the reaction.     

Divalent NI Compounds: Identifying new Carbocyclic Carbenes to Design Nitreones using Quantum Chemical Methods

Nitreones are compounds with oxidation state 1 at the nitrogen, these compounds carry formal positive charge as well as two lone pairs of electrons at nitrogen center. These compounds are also known as divalent N^I compounds and can be represented with the general formula L → N⁺ ← L, where L is an electron donating ligand. In the recent past, several divalent N^I compounds have been reported with L = N-heterocyclic carbene (NHC), remote N-heterocyclic carbene (rNHC), carbocyclic carbene (CCC) and diaminocarbene. Recently, our group reported that a novel six-membered CCC (cyclohexa-2,5-diene-4-[diaminomethynyl]-1-ylidene) can stabilize N⁺ center in nitreones. As an independent carbene, this species is very unstable. In this work, modulation of this CCC using (a) annulation, (b) heterocyclic ring modification, (c) substitutions adjacent to the carbenic carbon, (d) exocyclic double bond insertion and (e) ring contraction, has been reported. These modulations and quantum chemical analyses helped in the identification of five new six-membered CCCs which carry improved donation and stability properties. Further, these CCCs were employed in the design of new divalent N^I compounds (nitreones) which carry coordination bonds between ligands and N⁺ center. The molecular and electronic structure properties, and the donor→acceptor coordination interactions present in the resultant low oxidation state divalent N^I compounds have been explored.     

Rings Whose Nilpotent Elements form a Levitzki Radical Ring

In this article, we first discuss the relations among JH^r = 0, JH^r?1·H = 0, and JH^r·x = 0. Then we give a counterexample to the question mentioned in the Remarks of [3 Cheng, C. C., Sakkalis, T., Wang, S. S. S. (1994). A case of the Jacobian conjecture. J. Pure and Applied Algebra 96:15–18.[Crossref], [Web of Science ®] , [Google Scholar]] and prove the equivalence among JH(x⁽¹⁾)JH(x⁽²⁾)…JH(x^(r)) = 0, JH(x⁽¹⁾)JH(x⁽²⁾)…JH(x^(r?1))·H(x^(r)) = 0, and JH(x⁽¹⁾)JH(x⁽²⁾)…JH(x^(r))·x^(r) = 0. Finally, we give partial answer to Conjecture 2 in [4 Connell, E., Zweibel, J. (1991). Exact and coexact matrices. J. Algebra 142:110–117.[Crossref], [Web of Science ®] , [Google Scholar]].     

基于NI WSN的智能家居监控系统设计

随着物联网和计算机技术的不断发展,智能化、网络化、信息化是现代家居系统的必然发展趋势。将NI无线传感器网络(WSN)技术引入到智能家居监控系统的设计中,基于NI WSN系列产品进行了无线智能家居系统的总体框架、硬件型号和软件流程设计。系统的传感器节点分别采集盗情、烟雾、温湿度等参数,以无线形式通过网关将数据传输至上位机PC,在PC端利用Labview软件实现了智能家居防盗系统、火灾报警系统、环境舒适度等参数的实时在线监控,取得了良好的人机交互界面,并具有远程终端监控功能。该智能家居监控系统具备低功耗、实时性好、易扩展及可现实远程监控等优点,在智能家居领域具有广阔的市场前景和推广应用价值。     

航电设备通用检测维护台的设计

为了适应机载武器装备系统的多样化以及通用性要求,搭建了基于PXI总线的航电设备通用检测维护台,在系统架构、硬件设计以及软件开发等各方面进行了通用性设计。该航电设备通用检测维护台基于PXI构架,挂装不同种类的适配器,操作通用平台上的人机接口,可满足多种设备的检测、测试任务。航电设备通用检测维护台在一个机柜内实现了人机交互操作,大功率、高精度、多种类通用电源及PXI智能测试平台等的高度集成。该通用平台具有良好的通用性和扩展性,适用多种机型、多种航电设备。通用平台已在某型航电设备的检测维护中完成了工程验证,系统性能稳定,适用性强,可实现多种航电设备的检测维护工作,也可推广至海军舰艇、兵器车载装备等。