Rapid and label-free classification of pathogens based on light scattering,reduced power spectral features and support vector machine

The rapid identification of pathogens is crucial in controlling the food quality and safety. The proposed system for the rapid and label-free identification of pathogens is based on the principle of laser scattering from the bacterial microbes. The clinical prototype consists of three parts: the laser beam, photodetectors, and the data acquisition system. The bacterial testing sample was mixed with 10 mL distilled water and placed inside the machine chamber. When the bacterial microbes pass by the laser beam, the scattering of light occurs due to variation in size, shape, and morphology. Due to this reason, different types of pathogens show their unique light scattering patterns. The photo-detectors were arranged at the surroundings of the sample at different angles to collect the scattered light. The photodetectors convert the scattered light intensity into a voltage waveform. The waveform features were acquired by using the power spectral characteristics, and the dimensionality of extracted features was reduced by applying minimal-redundancy-maximal-relevance criterion (mRMR). A support vector machine (SVM) classifier was developed by training the selected power spectral features for the classification of three different bacterial microbes. The resulting average identification accuracies of E. faecalis,E. coli and S. aureus were 99%, 87%, and 94%, respectively. The overall experimental results yield a higher accuracy of 93.6%, indicating that the proposed device has the potential for label-free identification of pathogens with simplicity, rapidity, and cost-effectiveness.     

Conversion of E4 (E4=P4, As4, AsP3) by Ni(0) and Ni(I) Synthons – A Comparative Study

The reactivity of white phosphorus and yellow arsenic towards two different nickel nacnac complexes is investigated. The nickel complexes [(L¹Ni)₂tol] ( 1 , L¹=[{N(C₆H₃ⁱPr₂-2,6)C(Me)}₂CH]⁻) and [K₂][(L¹Ni)₂(μ,η^{1 : 1}-N₂)] ( 6 ) were reacted with P₄, As₄ and the interpnictogen compound AsP₃, respectively, yielding the homobimetallic complexes [(L¹Ni)₂(μ-η²,κ¹:η²,κ¹-E₄)] (E=P ( 2 a ), As ( 2 b ), AsP₃ ( 2 c )), [(L¹Ni)₂(μ,η^{3 : 3}-E₃)] (E=P ( 3 a ), As ( 3 b )) and [K@18-c-6(thf)₂][L¹Ni(η^{1 : 1}-E₄)] (E=P ( 7 a ), As ( 7 b )), respectively. Heating of 2 a , 2 b or 2 c also leads to the formation of 3 a or 3 b . Furthermore, the reactivity of these compounds towards reduction agents was investigated, leading to [K₂][(L¹Ni)₂(μ,η^{2 : 2}-P₄)] ( 4 ) and [K@18-c-6(thf)₃][(L¹Ni)₂(μ,η^{3 : 3}-E₃)] (E=P ( 5 a ), As ( 5 b )), respectively. Compound 4 shows an unusual planarization of the initial Ni₂P₄-prism. All products were comprehensively characterized by crystallographic and spectroscopic methods.     

硫鸟嘌呤修饰的Mn:ZnS QDs磷光探针检测铂(Ⅲ)

通过水相合成法制备了硫鸟嘌呤(TG)修饰的锰掺杂硫化锌量子点(TG-Mn:ZnS QDs)。加入Pt⁴⁺后,Pt⁴⁺会与硫鸟嘌呤上的氮原子结合形成N-Pt⁴⁺配位结构附着在TG-Mn:ZnS QDs的表面,随着Pt⁴⁺浓度的增加,TG-Mn:ZnS QDs-Pt⁴⁺体系发生电子转移而导致磷光逐渐被猝灭,基于此构建了检测Pt⁴⁺的磷光探针。实验中考察了p H、时间对Pt⁴⁺猝灭TG-Mn:ZnS QDs磷光强度的影响。在最佳实验条件下,Pt⁴⁺浓度在0.06~2.4μg/mL范围内与TG-Mn:ZnS QDs的磷光强度呈良好的线性关系y=0.0884x+0.2319,R²=0.991,方法检出限(3σ/n)为1.3μg/mL。该磷光探针适用于实际样品中Pt⁴⁺含量的测定。     

高力学强度细菌纤维素气凝胶纤维的连续化制备

气凝胶纤维因其高外表面积和高柔韧性在能量管理系统中具有潜在应用而引起了广泛关注.但是,目前制备的气凝胶纤维力学强度较低,限制了其实际应用.为提高气凝胶纤维力学性能,在始终保持细菌纤维素(BC)纳米纤维处于湿态下,利用NaOH/尿素/硫脲复合溶剂直接低温溶解原生BC,获得透明的BC纺丝原液;通过湿法纺丝制备了BC水凝胶纤维,经过水洗和冷冻干燥后处理,制得BC气凝胶纤维.采用偏光显微镜(POM)、13C核磁共振(13C-NMR)和高级旋转流变仪研究BC在复合溶剂中的溶解过程与状态;利用全反射傅里叶变换红外吸收光谱(ATR-FTIR)、X射线衍射(XRD)和热失重(TG)研究BC溶解前后结构与性能变化;利用场发射扫描电镜(FESEM)、全自动比表面积和孔径分布分析仪、单丝强力仪对获得的BC气凝胶纤维结构与性能进行表征.结果表明,复合溶剂在?15℃条件下可以直接溶解原生湿态BC,最高溶解浓度为3 wt%;采用湿法纺丝制得高度多孔的连续BC气凝胶纤维,比表面积高达192 m^2/g且具有优异的力学性能,断裂强度和杨氏模量高达(9.36±1.68)MPa和(176±17.55)MPa,如0.4 mg BC气凝胶纤维可以支撑高于其本身质量5×10^4倍的重物.     

混合熔盐法低温合成Sm2Ti2S2O5及其光催化分解水产氢

以TiO2、TiS2及Sm2O3为前驱体,分别加入LiCl-KCl与LiCl-CsCl的最低共熔混合物作为熔盐,在较低温度下成功合成了Sm2Ti2S2O5(STSO)颗粒。通过对比不同温度下所制备产物的X射线衍射图,首次表明STSO的热力学结晶温度在520℃左右,远低于之前报道的650℃的最低合成温度。扫描电子显微镜照片显示,采用2种混合熔盐制备的STSO都呈片状形貌;同一合成温度下,采用LiCl-CsCl熔盐制备的STSO的厚度小于LiCl-KCl所得产物。采用出射光波长大于420 nm的氙灯作为光源,在含有Na2S-Na2SO3空穴牺牲剂的溶液中,所制备的STSO颗粒表现出最高35μmol·h-1的光催化分解水产氢活性以及20 h以上的产氢稳定性。     

Ag@硅氧倍半聚合物的合成及其对对硝基苯酚的催化还原性能

以氨丙基三乙氧基硅烷和草酰氯为原料,合成得到链上含亚氨基和羰基官能团的硅氧倍半聚合物。以此聚合物为载体,通过配位吸附和还原得到银纳米粒子（平均粒径约为15 nm）高度分散于硅氧烷聚合物表面的复合物。研究结果表明,复合物中银负载量（质量分数）约为13.66%,在水溶液中25℃、6 min内可将对硝基苯酚（4-NP）完全催化还原为对氨基苯酚（4-AP）,且7次循环使用后依然保持95%以上的催化活性。在常温常压条件下,催化剂的最高活性达到33.0 g_4-AP·g_Ag^-1,表现出优异的催化还原性能。     

A purely organic D-π-A-π-D emitter with thermally activated delayed fluorescence and room temperature phosphorescence for near-white OLED

A purely organic D-π-A-π-D type emitter showing thermally activated delayed fluorescence(TADF) and room temperature phosphorescence(RTP) was designed and synthesized by utilizing the benzophenone as an acceptor and the N-phenyl-2-napthylamine as a donor moiety.It exhibits considerable TADF character in doped PMMA film and room temperature phosphorescence with a long lifetime of 74 ms at466 nm in solid state.The devices with the configuration of ITO/Mo_2 O_3(4 nm)/mCP(30 nm)/mCP:x wt%NP2 BP/TmTyPB(60 nm)/LiF(1.5 nm)/AI(100 nm) were prepared by vacuum evaporation to explore their electroluminescent performance.Intere stingly,the non-doped device has obtained near-white emission with a fluorescence emission peak at 475 nm and a phosphore scence emission peak at 563 nm having the CIE coordinate of(0.23,0.32) and the maximum external quantum efficiency of 1.09%.     

Cu/Cu_2O nanoparticles co-regulated carbon catalyst for alkaline Al-air batteries

Developing high-efficiency,inexpensive,and steady non-precious metal oxygen reduction reaction(ORR) catalysts to displace Pt-based catalysts is significant for commercial applications of Al-air battery.Here,we have prepared the Cu/Cu_2 O-NC catalyst with excellent ORR performance and high stability,due to the synergistic effect of Cu and Cu_2 O nanoparticles.The half-wave potential(0.8 V) and the limiting-current density(5.20 mA/cm~2) of the Cu/Cu_2 O-NC are very close to those of the 20% Pt/C catalyst(0.82 V,5.10 mA/cm~2).Besides,it exhibits excellent performance with a maximal power density of 250 mW/cm~2 and a stable continuous discharge for more than 90 h in the Al-air battery test The promoting effects of Cu_2 O towards Cu-based ORR catalysts are illustrated as follows:(ⅰ) Cu_2 O is the major ORR active site by the redox of Cu(Ⅱ)/Cu(Ⅰ),which provides excellent ORR activities;(ⅱ) Cu can stabilize the location of Cu_2 O by assisting the electron transfer to Cu(Ⅱ)/Cu(Ⅰ) redox,which is conducive to the high stability of the catalyst.This work provides a useful strategy for enhancing the ORR performance of Cu-based catalysts.     

Visible light induced tandem reactions: An efficient one pot strategy for constructing quinazolinones using in-situ formed aldehydes under photocatalyst-free and room-temperature conditions

A facile tandem route has been developed for constructing quinazolinones from various aminobenzamides and in-situ generated aldehydes. Visible light was found to play a dual role: first oxidizes the alcohol to the aldehyde and then facilitates its cyclization with o-substituted aniline. Furthermore, alcohols are perfect alternatives to aldehydes because they are greener, more available, more economical, more stable, and less toxic than aldehydes. The first reaction step continuously provides material for the second step, which effectively reduces loss through volatilization, oxidation, and polymerization of the aldehyde, while avoiding its toxicity. A variety of quinazolinones can be prepared in the presence of visible light without any additional photocatalyst. The developed synthesis protocol proceeds with the merits of mild conditions, broad substrate scope, operational simplicity, and high atom efficiency, with an eco-energy source under metal-free, photocatalyst-free, and ambient conditions.     

极性晶体膜中强耦合激子的性质

在强耦合极化子模型基础上,采用Lee-Low-Pines(LLP)变分法研究了极性晶体膜中激子与表面光学(SO)声子强耦合、与体纵光学(LO)声子弱耦合体系的性质.讨论了极性晶体膜中激子的诱生势与膜厚度和温度的变化关系.结果表明:激子的诱生势不仅与电子-空穴间距离有关,而且与极性晶体膜厚度有关,同时温度对激子诱生势的影响十分显著.