bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrikas «Provodņik» darbība Rīgā un tās darbinieki – Rīgas Politehnikuma / Rīgas Politehniskā institūta absolventi
Authors: Zigmunde Alīda , Šapovalovs Oļegs
Published: May 2019

Rakstā dots pārskats par 1888. gada jūnijā Rīgā, Sarkandaugavā, nodibinātā krievu un franču kopuzņēmuma – gumijas, gutaperčas un telegrāfa piederumu fabriku sabiedrības «Provodņik» darbību. Pirms Pirmā pasaules kara «Provodņik» kļuva par vienu no četrām lielākajām gumijas fabrikām pasaulē. 1915. gadā fabriku evakuēja uz Maskavu, 1918. gadā uzņēmumu nacionalizēja.  1921.   gadā  akcionāri  nolēma  fabrikas  bijušajās  telpās atjaunot «Provodņik» darbību, bet situācija bija mainījusies. Tā vairākus gadus darbojās kā kokapstrādes rūpnīca (1925–1935), bet nekad nesasniedza tādu uzplaukumu kā 19. gadsimta beigās un 20. gadsimta sākumā. 20. gadsimta 30. gadu beigās likvidēta. Nozīmīgu ieguldījumu «Provodņik» darbā un attīstībā devuši Rīgas Politehnikuma (RP) un Rīgas Politehniskā institūta (RPI) absolventi, kuri apzināti, veicot dokumentos balstītu pētījumu.
Arhitekta Indriķa Blankenburga (1887–1944) dzimta un projekti laikmetu griežos
Authors: Zvaigzne Māris , Zigmunde Alīda , Gudro Ilze
Published: May 2019

Аrhitekts Indriķis Blankenburgs (1887–1944), Rīgas Politehniskā institūta (RPI) Arhitektūras nodaļas absolvents (1913), ir viens no pazīstamākajiem skolu ēku projektētajiem Latvijā starpkaru laikā. Vairums no viņa vairāk nekā 30 projektēto skolu un citu celtņu joprojām tiek izmantotas arhitekta sākotnēji paredzētajiem mērķiem. Izmantojot Latvijas Valsts vēstures arhīva dokumentus un bibliotēku krājumus, rakstā izsekots Blankenburgu dzimtai, kā arī ieskicēts I. Blankenburga devums skolu arhitektūrā, sastādīts arhitekta projektēto skolu saraksts.
Arhitekta Indriķa Blankenburga projektētā Ļaudonas lauksaimniecības skolas ēka
Authors: Zvirgzdiņš Indulis
Published: May 2019

Ļaudonas divgadīgās lauksaimniecības skolas būvplāns (1923), jādomā, ir pirmais Rīgas Politehniskā institūta 1913. gada absolventa arhitekta Indriķa Blankenburga (1877–1944) darbs mācību iestāžu projektēšanā. Tā gan nebija jaunceltne, bet nama rekonstrukcija, pārbūve pēc ugunsgrēka, tomēr te varam atrast atsevišķus elementus, kas izmantoti arī vēlākās jaunbūvēs. Izglītībai ēka kalpoja vairāk nekā pusgadsimtu. Raksts veltīts celtnes vēsturei, pieminēti arī daži citi I. Blankenburga būvplāni Madonā.
Rīgas Tehniskās universitātes svarīgāko notikumu hronoloģija
Authors: Zigmunde Alīda , Lapsa Rūta , Gudro Ilze
Published: May 2019

2017./2018. STUDIJU GADS 1. septembrī Uz rektora tradicionālo tikšanos ar mācībspēkiem un darbiniekiem ierodas Ministru prezidents Māris Kučinskis, kurš rektoram akadēmiķim Leonīdam Ribickim pasniedz Ministru prezidenta Pateicības rakstu «Par mūža ieguldījumu Latvijas zinātnes attīstībā un neatlaidīgiem centieniem pilnveidot eksakto zinātņu studijas, inovāciju radīšanu un tehnoloģiju pārnesi, veicinot izglītības līmeņa paaugstināšanu un tautsaimniecības attīstību valstī».
Live cell imaging of meiosis in Arabidopsis thaliana
Authors: Prusicki Maria A , Keizer Emma M , van Rosmalen Rik P , Komaki Shinichiro , Seifert Felix , Müller Katja , Wijnker Erik , Fleck Christian , Schnittger Arp
Published: May 2019

To follow the dynamics of meiosis in the model plant Arabidopsis, we have established a live cell imaging setup to observe male meiocytes. Our method is based on the concomitant visualization of microtubules (MTs) and a meiotic cohesin subunit that allows following five cellular parameters: cell shape, MT array, nucleus position, nucleolus position, and chromatin condensation. We find that the states of these parameters are not randomly associated and identify 11 cellular states, referred to as landmarks, which occur much more frequently than closely related ones, indicating that they are convergence points during meiotic progression. As a first application of our system, we revisited a previously identified mutant in the meiotic A-type cyclin TARDY ASYNCHRONOUS MEIOSIS (TAM). Our imaging system enabled us to reveal both qualitatively and quantitatively altered landmarks in tam, foremost the formation of previously not recognized ectopic spindle- or phragmoplast-like structures that arise without attachment to chromosomes.
Cysteine dioxygenase 1 is a metabolic liability for non-small cell lung cancer
Authors: Kang Yun Pyo , Torrente Laura , Falzone Aimee , Elkins Cody M , Liu Min , Asara John M , Dibble Christian C , DeNicola Gina M
Published: May 2019

NRF2 is emerging as a major regulator of cellular metabolism. However, most studies have been performed in cancer cells, where co-occurring mutations and tumor selective pressures complicate the influence of NRF2 on metabolism. Here we use genetically engineered, non-transformed primary murine cells to isolate the most immediate effects of NRF2 on cellular metabolism. We find that NRF2 promotes the accumulation of intracellular cysteine and engages the cysteine homeostatic control mechanism mediated by cysteine dioxygenase 1 (CDO1), which catalyzes the irreversible metabolism of cysteine to cysteine sulfinic acid (CSA). Notably, CDO1 is preferentially silenced by promoter methylation in human non-small cell lung cancers (NSCLC) harboring mutations in KEAP1, the negative regulator of NRF2. CDO1 silencing promotes proliferation of NSCLC by limiting the futile metabolism of cysteine to the wasteful and toxic byproducts CSA and sulfite (SO32-), and depletion of cellular NADPH. Thus, CDO1 is a metabolic liability for NSCLC cells with high intracellular cysteine, particularly NRF2/KEAP1 mutant cells.
Light-Controlled Polarization of MM-Waves with Photo-Excited Gratings in a Resonant Semiconductor Slab
Authors: Yurchenko V. , Navruz T. , Ciydem M. , Altintas A.
Published: May 2019

We investigated photoconductive gratings in the resonant semiconductor layers as light-controlled polarizers for the millimeter (MM) waves. We compared the effects of strip-like, wire-like, and fin-like gratings excited by the red light and the IR radiation in Silicon wafers, respectively. The fin-like gratings are shown to be the preferred structures that can operate at the limited light intensity. The light-sensitive shift of maxima of transmitted power and polarizing efficiency towards the lower frequency band is observed. The effect makes photoconductive gratings and similar patterns potentially suitable for the design of light-controlled frequency-tuning and frequency-modulating components of resonant quasi-optical devices.
Food Derived Bioactive Peptides for Health Enhancement and Management of Some Chronic Diseases
Authors: Ogori A. F. , Girgih A. T. , Abu J. O. , Eke M. O.
Published: May 2019

The bioactive peptides produced by enzymatic hydrolysis, acid hydrolysis and fermentation approach have been identified and used widely in research. These methods are important in enhancement or prevention and management of chronic diseases that are ravaging the world such as type -2-diabetes, hypertension, oxidative stress, cancer, and obesity. Sources of bioactive peptides have been established ranging from plant to animal and marine foods that have pharmacological effects; however these effects are dependent on target cells and peptides structure and conformations.  Plants such as hemp and animal source such as milk among others validate the findings of In vitro and In-vivo studies and the efficiency of these bioactive peptides in the management of certain chronic diseases. This article reviews the literature on bioactive peptides with concern on food sources, production and bioactive peptides application in enhancement of health and management of hypertension, diabetes and oxidative stress.  Future research efforts on bioactive peptides should be directed towards elucidating specific sequenced bioactive peptides and their molecular mechanisms, through In-vivo and In-vitro studies for specific health condition in human using nutrigenomics and peptideomic approaches.
Functional Analysis Evolution History of Gonadal Soma-derived Factor (gsdf) in Black Rockfish, Sebastes schlegelii
Authors: Xuemei Li. , Wang Xuliang , Wang Zhigang
Published: May 2019

As a teleost- and gonad-specific growth factor, gsdf has been indicated to play an important role in sex differentiation and determination. In this study, the complete open reading frame (ORF) of gsdf was isolated from black rockfish, Sebastes schlegelii. Bioinformatics analysis showed that there is a conserved transforming growth factor-β (TGF-β) domain located on the C-terminus of Gsdf. Multiple sequence alignments revealed that fish gsdf were highly conserved in TGF-β domain which suggested their functional conservatism. Synteny analysis provided evidence for the hypothesis that gsdf was originated from fish-specific genome duplication (FSGD). To further explore its function, the expression pattern was examined based on the RNA-seq data and the result showed that significantly sexually dimorphic expression existing between male and female individuals. These results suggested that gsdf might play an important role in maintenance of male characteristics in Sebastes schlegelii.
Reducing Salinity Stress in Murcott Mandarin Orchards Using Different Soil Amendments
Authors: Abou-Baker Nesreen H. , Hamed Nadia A. , Abdel-Aziz R. A. , Salem A. S.
Published: May 2019

Aims: The response of “Murcott” mandarin trees budded on Volkamer Lemon rootstock grown in salt-affected soil to different alleviating salinity stress additions was studied.

Study Design: This research was designed to fit The complete randomize block design (CRBD).

Place and Duration of Study: The present study was carried out in a private “Murcott” mandarin orchard located in “El-Adlia Association”, El-Sharqia Governorate, Egypt, during two successive seasons 2014/2015 and 2016/2017.

Methodology: Eight different treatments were used as follow: 1) Control, 2) Magnetite at 138 kg/ha (Mag, knowing that ha = 10000 m2), 3) Effective microorganisms at the rate of 12 L/ha. (EM), 4) Biotic at the rate of 12 L/ha. (B), 5) Mag+B, 6) Mag+EM, 7) B+EM and 8) Mag+B+EM.

Results: These different treatments mitigated salinity stress, reduced leaves osmotic pressure, thus increased fruit set, fruit yield, fruit quality, root distribution, photosynthetic pigments and mineral concentrations in leaves of Murcott trees compared with the control. Proline accumulations in fresh leaves, as well as soil pH and EC at the end of the two seasons also were recorded.

Conclusion: The combination between B and EM in the presence or absence of Mag enhanced the ability of mandarin to alleviate salt stress and produced the highest yield and fruit quality.
Factors Militating against Effective Teaching and Learning of Computer in Secondary Schools in Enugu State Nigeria
Authors: N Ogbonna Mercy.
Published: May 2019

The teaching and learning of computers in secondary schools is very beneficial for preparation of students for more challenging education in the University. However, many factors militate against the effective computer education in the schools. This study sought to assess these factors in Enugu State Nigeria. Specifically it sought to assess teachers-related factors; students-related factors; government-related factors and school administrative factors that militate against effective teaching and learning of computer in the State. The study adopted survey research method and hundred questionnaires were used for the study.  Data were analysed with the use of descriptive statistics (mean) in SPSS. Respondents agreed that teachers based factors that contribute to ineffective teaching and learning of computers in secondary schools included that teachers of the subject were unqualified (=2.9) and lack experience (=2.6). Students based included absenteeism by students (=2.7) and lack of interest by students (=2.7). Government based factors included that government provide voluminous curriculum (=2.9) and do not provide funds (=3.2). School administration based factors were that mismanagement of procured instructional materials (=2.9) and mis-use of provided funds (=2.9). This study concludes that students, teachers, government and school administration have important roles to play for effective teaching and learning of computer in secondary schools. For a way forward, the study recommends that government and individuals should encourage in and out of school computer education by establishing learning centres in the State. Computer teachers should always be provided with on-the-job training or re-training programmes. Government and school administration should as a matter of priority provide computer systems and other lacking instructional materials in their schools. Students should attend to classes and improve their interest in computer education.
Recent Advances in Applications of Sorted Single‐Walled Carbon Nanotubes
Authors: Bati Abdulaziz S. R. , Yu LePing , Batmunkh Munkhbayar , Shapter Joseph G.
Published: May 2019

Single‐walled carbon nanotubes (SWCNTs) exhibit outstanding properties that make them appealing in a wide range of applications. However, their properties are variable depending on the tube helicity (chirality), which has been a challenge for a long time and needs to be effectively controlled. In recent years, tremendous efforts have been made to control the electrical type/chirality of nanotubes through both direct controlled synthesis and postsynthesis separation methods. Driven by these breakthroughs, the applications of separated families of SWCNTs in various fields have emerged as a new topic of research. In this Review, an overview of recent advances in the use of highly purified and well‐separated SWCNTs in a comprehensive range of applications is presented including photovoltaics, transistors, batteries, sensors, light emitters, biological/medical fields, and others. Finally, important future directions for the utilization of separated SWCNTs in these fields are provided.
Properties of Excitons and Photogenerated Charge Carriers in Metal Halide Perovskites
Authors: Jiang Ying , Wang Xiao , Pan Anlian
Published: May 2019

Metal halide perovskites (MHPs) have recently attracted great attention from the scientific community due to their excellent photovoltaic performance as well as their tremendous potential for other optoelectronic applications such as light‐emitting diodes, lasers, and photodetectors. Despite the rapid progress in device applications, a solid understanding of the photophysical properties behind the device performance is highly desirable for MHPs. Here, the properties of excitons and photogenerated charge carriers in MHPs are explored. The unique dielectric constant properties, crystal–liquid duality, and fundamental optical processes of MHPs are first discussed. The properties of excitons and related phenomena in MHPs are then detailed, including the exciton binding energy determined by various methods and their influence factors, exciton dynamics, exciton–photon coupling and related applications, and exciton–phonon coupling in MHPs. The properties of photogenerated free charge carriers in MHPs such as the carrier diffusion length, mobility, and recombination are described. Recent progress in various applications is also demonstrated. Finally, a conclusion and perspectives of future studies for MHPs are presented.
Defect‐Rich Heterogeneous MoS2/NiS2 Nanosheets Electrocatalysts for Efficient Overall Water Splitting
Authors: Lin Jinghuang , Wang Pengcheng , Wang Haohan , Li Chun , Si Xiaoqing , Qi Junlei , Cao Jian , Zhong Zhengxiang , Fei Weidong , Feng Jicai
Published: May 2019

Designing and constructing bifunctional electrocatalysts is vital for water splitting. Particularly, the rational interface engineering can effectively modify the active sites and promote the electronic transfer, leading to the improved splitting efficiency. Herein, free‐standing and defect‐rich heterogeneous MoS2/NiS2 nanosheets for overall water splitting are designed. The abundant heterogeneous interfaces in MoS2/NiS2 can not only provide rich electroactive sites but also facilitate the electron transfer, which further cooperate synergistically toward electrocatalytic reactions. Consequently, the optimal MoS2/NiS2 nanosheets show the enhanced electrocatalytic performances as bifunctional electrocatalysts for overall water splitting. This study may open up a new route for rationally constructing heterogeneous interfaces to maximize their electrochemical performances, which may help to accelerate the development of nonprecious electrocatalysts for overall water splitting.
Nanoionic Resistive‐Switching Devices
Authors: Zhu Xiaojian , Lee Seung Hwan , Lu Wei D.
Published: May 2019

Advances in the understanding of nanoscale ionic processes in solid‐state thin films have led to the rapid development of devices based on coupled ionic–electronic effects. For example, ion‐driven resistive‐switching (RS) devices have been extensively studied for future memory applications due to their excellent performance in terms of switching speed, endurance, retention, and scalability. Recent studies further suggest that RS devices are more than just resistors with tunable resistance; instead, they exhibit rich and complex internal ionic dynamics that equip them with native information‐processing capabilities, particularly in the temporal domain. RS effects induced by the migration of different types of ions, often driven by an electric field, are discussed. It is shown that, by taking advantage of the different state variables controlled by the ionic processes, important synaptic functions can be faithfully implemented in solid‐state devices and networks. Recent efforts on improving the controllability of ionic processes to optimize device performance are also discussed, along with new opportunities for material design and engineering enabled by the ability to control ionic processes at the atomic scale.
Highly Sensitive, Stretchable Strain Sensor Based on Ag@COOH‐Functionalized CNTs for Stroke and Pronunciation Recognition
Authors: Pei Zhen , Liu Yan , Zhang Qiang , Zhao Dong , Wang Jie , Yuan Zhongyun , Zhang Wendong , Sang Shengbo
Published: May 2019

Combining metal and carbon nanomaterials is an effective way to significantly enhance the performance of soft strain sensors. The role of carbon nanotubes (CNTs) functionalized with different chemical groups in improving the properties of nanosilver‐coated carbon nanotubes (Ag@CNT) is investigated. The functionalized CNTs are first calculated with different chemical groups combined with the silver atoms. Ag@COOH‐functionalized CNTs exhibit greater binding energy and a smaller bandgap, which leads to better hydrophilicity, stability, and stronger bonding. Ag@CNTs are then synthesized using pristine CNT, OH‐functionalized CNT, and COOH‐functionalized CNT. Strain sensors are fabricated by wrapping the sensing material with polydimethylsiloxane (PDMS) to form a sandwich structure. Tests of these sensors are consistent with the simulation results; that is, COOH‐functionalized CNTs can greatly enhance the performance of Ag@CNT. In particular, Ag@COOH‐functionalized CNT sensors exhibit a strain range of nearly 40%, an initial resistance of 6.83 Ω, and excellent sensitivity, with a GF of 172. They can be applied in stroke detection and pronunciation recognition. This system also has great potential for foldable phones and flexible writing pads.
Protecting‐Group‐Controlled Enzymatic Glycosylation of Oligo‐N‐Acetyllactosamine Derivatives
Authors: Gagarinov Ivan A. , Li Tiehai , Wei Na , Sastre Toraño Javier , de Vries Robert P. , Wolfert Margreet A. , Boons Geert‐Jan
Published: May 2019

We describe a chemoenzymatic strategy that can give a library of differentially fucosylated and sialylated oligosaccharides starting from a single chemically synthesized tri‐N‐acetyllactosamine derivative. The common precursor could easily be converted into 6 different hexasaccharides in which the glucosamine moieties are either acetylated (GlcNAc) or modified as a free amine (GlcNH2) or Boc (GlcNHBoc). Fucosylation of the resulting compounds by a recombinant fucosyl transferase resulted in only modification of the natural GlcNAc moieties, providing access to 6 selectively mono‐ and bis‐fucosylated oligosaccharides. Conversion of the GlcNH2 or GlcNHBoc moieties into the natural GlcNAc, followed by sialylation by sialyl transferases gave 12 differently fucosylated and sialylated compounds. The oligosaccharides were printed as a microarray that was probed by several glycan‐binding proteins, demonstrating that complex patterns of fucosylation can modulate glycan recognition.
Ultrathin Metal–Organic Framework Nanosheets with Ultrahigh Loading of Single Pt Atoms for Efficient Visible‐Light‐Driven Photocatalytic H2 Evolution
Authors: Zuo Quan , Liu Tingting , Chen Chuanshuang , Ji Yi , Gong Xueqing , Mai Yiyong , Zhou Yongfeng
Published: May 2019

A surfactant‐stabilized coordination strategy is used to make two‐dimensional (2D) single‐atom catalysts (SACs) with an ultrahigh Pt loading of 12.0 wt %, by assembly of pre‐formed single Pt atom coordinated porphyrin precursors into free‐standing metal–organic framework (MOF) nanosheets with an ultrathin thickness of 2.4±0.9 nm. This is the first example of 2D MOF‐based SACs. Remarkably, the 2D SACs exhibit a record‐high photocatalytic H2 evolution rate of 11 320 μmol g−1 h−1 via water splitting under visible light irradiation (λ>420 nm) compared with those of reported MOF‐based photocatalysts. Moreover, the MOF nanosheets can be readily drop‐casted onto solid substrates, forming thin films while still retaining their photocatalytic activity, which is highly desirable for practical solar H2 production.
Hydrogen by Deuterium Substitution in an Aldehyde Tunes the Regioselectivity by a Nonheme Manganese(III)–Peroxo Complex
Authors: Barman Prasenjit , Cantú Reinhard Fabián G. , Bagha Umesh Kumar , Kumar Devesh , Sastri Chivukula V. , de Visser Sam P.
Published: May 2019

Mononuclear nonheme MnIII‐peroxo complexes are important intermediates in biology, and take part in oxygen activation by photosystem II. Herein, we present work on two isomeric biomimetic side‐on MnIII‐peroxo intermediates with bispidine ligand system and reactivity patterns with aldehydes. The complexes are characterized with UV/Vis and mass spectrometric techniques and reaction rates with cyclohexane carboxaldehyde (CCA) are measured. The reaction gives an unusual regioselectivity switch from aliphatic to aldehyde hydrogen atom abstraction upon deuteration of the substrate, leading to the corresponding carboxylic acid product for the latter, while the former gives a deformylation reaction. Mechanistic details are established from kinetic isotope effect studies and density functional theory calculations. Thus, replacement of C−H by C−D raises the hydrogen atom abstraction barriers and enables a regioselectivity switch to a competitive pathway that is slightly higher in energy.
Wall‐ and Hybridisation‐Selective Synthesis of Nitrogen‐Doped Double‐Walled Carbon Nanotubes
Authors: Carini Marco , Shi Lei , Chamberlain Thomas W. , Liu Meng , Valenti Giovanni , Melle‐Franco Manuel , Paolucci Francesco , Khlobystov Andrei N. , Pichler Thomas , Mateo‐Alonso Aurelio
Published: May 2019

Controlled nitrogen‐doping is a powerful methodology to modify the properties of carbon nanostructures and produce functional materials for electrocatalysis, energy conversion and storage, and sensing, among others. Herein, we report a wall‐ and hybridisation‐selective synthetic methodology to produce double‐walled carbon nanotubes with an inner tube doped exclusively with graphitic sp2‐nitrogen atoms. Our measurements shed light on the fundamental properties of nitrogen‐doped nanocarbons opening the door for developing their potential applications.
Isostructural Three‐Dimensional Covalent Organic Frameworks
Authors: Gao Chao , Li Jian , Yin Sheng , Lin Guiqing , Ma Tianqiong , Meng Yi , Sun Junliang , Wang Cheng
Published: May 2019

Herein, we reported the designed synthesis of three isostructural three‐dimensional covalent organic frameworks (3D COFs) with ‐H, ‐Me, or ‐F substituents, which have similar crystallinity and topology. Their crystal structures were determined by continuous rotation electron diffraction (cRED), and all three 3D COFs were found to adopt a fivefold interpenetrated pts topology. More importantly, the resolution of these cRED datasets reached up to 0.9–1.0 Å, enabling the localization of all non‐hydrogen atomic positions in a COF framework directly by 3D ED techniques for the first time. In addition, the precise control of the pore environments through the use of different functional groups led to different selectivities for CO2 over N2. We have thus confirmed that polycrystalline COFs can be definitely studied to the atomic level as other materials, and this study should also inspire the design and synthesis of 3D COFs with tailored pore environments for interesting applications.
Charge Polarization from Atomic Metals on Adjacent Graphitic Layers for Enhancing the Hydrogen Evolution Reaction
Authors: Zhang Longzhou , Jia Yi , Liu Hongli , Zhuang Linzhou , Yan Xuecheng , Lang Chengguang , Wang Xin , Yang Dongjiang , Huang Keke , Feng Shouhua , Yao Xiangdong
Published: May 2019

Atomic metal species‐based catalysts (AMCs) show remarkable possibilities in various catalytic reactions. The coordination configuration of the metal atoms has been widely recognized as the determining factor to the electronic structure and the catalytic activity. However, the synergistic effect between the adjacent layers of the multilayered AMCs is always neglected. We reported an atomic Co and Pt co‐trapped carbon catalyst, which exhibits a ultrahigh activity for HER in the wide range of pH (η10=27 and 50 mV in acidic and alkaline media, respectively) with ultralow metal loadings (1.72 and 0.16 wt % for Co and Pt, respectively), which is much superior to the commercial Pt/C. Theoretical analysis reveals that the atomic metals on the inner graphitic layers significantly alter the electronic structure of the outmost layer, thus tailoring the HER activity. This finding arouses a re‐thinking of the intrinsic activity origins of AMCs and suggests a new avenue in the structure design of AMCs.
Reversible Switching of Catalytic Activity by Shuttling an Atom into and out of Gold Nanoclusters
Authors: Cai Xiao , Saranya Govindarajan , Shen Kangqi , Chen Mingyang , Si Rui , Ding Weiping , Zhu Yan
Published: May 2019

It is challenging to control the catalyst activation and deactivation by removal and addition of only one central atom, as it is almost impossible to precisely abstract an atom from a conventional catalyst and analyze its catalysis. Here we report that the loss of one central atom in Au25 (resulting in Au24) enhances the catalytic activity in the oxidation of methane compared to the original Au25. More importantly, the activity can be readily switched through shuttling the central atom into Au24 and out of Au25. This work will serve as a starting point for design rules on how to control catalytic performance of a catalyst by an atom alteration.
Effect of the formation of silver nano‐binuclear complex on the refinement of cytotoxic and antibacterial potency of coumarin Schiff base: Spectroscopy, thermal, X‐ray diffraction analyses and density functional theory calculations
Authors: El‐Ansary Aida L. , Moustafa Hussein , Abdel‐Kader Nora S. , Farghaly Aya M.
Published: May 2019

A new Schiff base (SCH) was prepared using 8‐acetyl‐7‐hydroxy‐4‐methylcoumarin and sulfaclozine. Its silver complex was also synthesized. These compounds were subjected to elemental and spectral analyses. The silver complex was also subjected to thermogravimetric analysis, molar conductance measurements, scanning electron microscopy, energy‐dispersive X‐ray analysis and X‐ray diffraction measurements. The formula of the complex was determined as [(Ag2SCH(NO3)2]. The molar conductance indicates its non‐electrolyte character. The electronic structure and nonlinear optical parameters of SCH and its complex were investigated theoretically at the B3LYP/GENECP level. The geometry of the studied complex is non‐planar as indicated from the dihedral angles between central Ag metal ion and coordinated centres of SCH. Density functional theory calculations were also carried out to calculate the global properties of hardness, global softness and electronegativity. The calculated energy gap between HOMO and LUMO energies shows that charge transfer occurs within the studied complex. The total static dipole moment, the mean polarizability, the anisotropy of the polarizability and the mean first‐order hyperpolarizability were calculated and compared with those of urea as a reference material. The results of the mean first‐order hyperpolarizability showed that SCH and its silver complex are excellent candidates as nonlinear optical materials. The compounds were screened for their antimicrobial effect against various species of bacteria and fungi. Their anticancer activities were evaluated in vitro against the human cancer cell line MCF‐7 (human breast adenocarcinoma).
Synthesis and characterization of indium and thallium immobilized on isonicotinamide‐functionalized mesoporous MCM‐41: Two novel and highly active heterogeneous catalysts for selective oxidation of sulfides and thiols to their corresponding sulfoxides and disulfides
Authors: Molaei Somayeh , Ghadermazi Mohammad
Published: May 2019

Two highly ordered isonicotinamide (INA)‐functionalized mesoporous MCM‐41 materials supporting indium and thallium (MCM‐41‐INA‐In and MCM‐41‐INA‐Tl) have been developed using a covalent grafting method. A surface functionalization method has been applied to prepare Cl‐modified mesoporous MCM‐41 material. Condensation of this Cl‐functionalized MCM‐41 with INA leads to the formation of MCM‐41‐INA. The reaction of MCM‐41‐INA with In(NO3)3 or Tl(NO3)3 leads to the formation of MCM‐41‐INA‐In and MCM‐41‐INA‐Tl catalysts. The resulting materials were characterized using various techniques. These MCM‐41‐INA‐In and MCM‐41‐INA‐Tl catalysts show excellent catalytic performance in the selective oxidation of sulfides and thiols to their corresponding sulfoxides and disulfides. Finally, it is found that the anchored indium and thallium do not leach out from the surface of the mesoporous catalysts during reaction and the catalysts can be reused for seven repeat reaction runs without considerable loss of catalytic performance.
Highly efficient ring‐opening polymerization of tetrahydrofuran by anhydrous ferric chloride
Authors: Yang Hee Jung , Yoon Seok Won , Park Hee Sun , Lee Kyu Hyung , Hur Nam Hwi
Published: May 2019

Poly(tetramethylene ether glycol) (PTMG), widely used as a precursor in the fabrication of commodity polymers, is typically produced byacid‐catalyzed polymerization of tetrahydrofuran (THF). Herein, we report a detailed investigation of the cationic ring‐opening polymerization of THF catalyzed by ferric chloride (FeCl3), which can be considered as a strong Lewisacid. The polymerization reactions were performed in the presence of acetic anhydride at 20°C with FeCl3, which readily produced poly(tetramethylene ether glycol diester) (PTMG_DE). A maximum yield of 79.2% was obtained within 30 min using a FeCl3 to acetic anhydride molar ratio of 5:4. The resulting polymers generally exhibited low molecular weights and a narrow polydispersity index and could be easily converted into PTMG using aqueous NaOH. In contrast with the FeCl3‐acetic anhydride system, other iron‐based catalysts such as FeCl2 and FeCl3·6H2O did not show any noticeable activity in the polymerization of THF. The proposed mechanism involves initiation of the acetyl cation generated by FeCl3, propagation by nucleophilic addition of THF, and termination by the acetate anion, accounting for the high activity of the FeCl3 catalyst for THF polymerization. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47999.
N‐[2‐[(3‐Chlorophenyl)amino]‐phenyl]‐3‐(difluoromethyl)‐1‐methyl‐1H‐pyrazole‐4‐carboxamide: Synthesis, Crystal Structure, Molecular Docking and Biological Activities
Authors: Zhang Aigui , Yang Yihua , Yue Ying , Tao Ke , Hou Taiping , Jin Hong
Published: May 2019

In continuation of our previous research on the development of novel pyrazole‐4‐carboxamide with potential antifungal activity, compound SCU2028, namely N‐[2‐[(3‐chlorophenyl)amino]phenyl]‐3‐(difluoromethyl)‐1‐methyl‐1H‐pyrazole‐4‐carboxamide, was synthesized by new method, structurally characterized by IR, HR‐ESI‐MS, 1H‐ and 13C‐NMR spectra and further identified by single‐crystal X‐ray diffraction. In pot tests, compound SCU2028 showed good in vivo antifungal activity against Rhizoctonia solani (R. solani) and IC50 value of it was 7.48 mg L−1. In field trials, control efficacy of compound SCU2028 at 200 g.a.i. ha−1 was 42.30 % on the 7th day after the first spraying and 68.10 % on the 14th day after the second spraying, only slightly lower than that of thifluzamide (57.20 % and 71.40 %, respectively). Further in vitro inhibitory activity showed inhibitory ability of compound SCU2028 was 45‐fold higher than that of bixafen and molecular docking of compound SCU2028 to SDH predicted its binding orientation in the active site of the target protein SDH. These results suggested that compound SCU2028 was a potential fungicide for control of rice sheath blight.
Pulmonary lobectomy in two multitrauma patients under extracorporeal circulation placed preoperatively in an intensive care unit: A case report
Authors: Faidherbe Clément , De Kock Marc , Simonet Olivier , Vallot Frédéric , Ndjekembo Shango Didier
Published: May 2019

The clinical course of our two patients highlights the feasibility of using venovenous extracorporeal membrane oxygenation (ECMO) with heparin for multitraumatic patients needing thoracic surgery. Further research is required to determine if surgery can be performed with totally heparin‐free vv‐ECMO. All ICU teams should become familiar with this technique.
Kinetics of Furfural Hydrogenation over Bimetallic Overlayer Catalysts and the Effect of Oxygen Vacancy Concentration on Product Selectivity
Authors: Liu Ping , Qiu Weinan , Zhang Chunyang , Tan Qiqi , Zhang Chen , Zhang Wei , Song Yongji , Wang Hong , Li Cuiqing
Published: May 2019

Furfural hydrogenation over silica‐supported Co@Pd and Cu@Pd bimetallic overlayer catalysts was studied in this work. Both overlayer catalysts showed enhanced reactivity compared to pure Pd in furfural hydrogenation. Langmuir‐Hinshelwood kinetic study revealed that this enhanced reactivity could be attributed to the decreased hydrogen surface coverage on catalyst surface of overlayer catalysts compared to pure Pd during reaction, releasing more available active sites for surface reaction or furfural adsorption to take place. The effect of oxygen vacancy concentration on furfural hydrogenation product selectivity was also studied. It is proposed that oxygen vacancies were crucial for both furfural hydrodeoxygenation and aromatic ring hydrogenation, depending on the concentration of oxygen vacancies. This work provides new perspective for tuning the furfural hydrogenation product selectivity by altering the oxygen vacancy concentration.
Helicene Monomers and Dimers: Chiral Chromophores Featuring Strong Circularly Polarized Luminescence
Authors: Schaack Cédric , Arrico Lorenzo , Sidler Eric , Górecki Marcin , Di Bari Lorenzo , Diederich François
Published: May 2019

The synthesis and chiroptical properties of a series of enantiomerically pure, C2‐symmetrical carbo[6]helicene dimers are reported. Two helicene cores are connected through a buta‐1,3‐diyne‐1,4‐diyl linker or a heteroaromatic bridge and bear arylethynyl substituents at their 15‐positions. This ensures the possibility of extended electronic communication throughout the whole molecule. The new chromophores exhibit intense ECD spectra with strong bands in the UV/Vis region well above 400 nm. The anisotropy factor gabs (defined as Δϵ/ϵ) reaches values up to 0.047, which are unusually large for single organic molecules. They also display blue fluorescence, with good quantum yields (Φf∼0.25). The emitted light is circularly polarized to an outstanding extent: in some cases, the luminescence dissymmetry factor glum=2(IL−IR)/(IL+IR) attains values of |0.025|. To the best of our knowledge, such values are among the highest ever reported for non‐aggregated organic fluorophores.
Transition‐Metal Oxides/Carbides@Carbon Nanotube Composites as Multifunctional Electrocatalysts for Challenging Oxidations and Reductions
Authors: Xing Xiaolin , Liu Rongji , Cao Kecheng , Kaiser Ute , Streb Carsten
Published: May 2019

The rapid development of renewable‐energy technologies such as water splitting, rechargeable metal–air batteries, and fuel cells requires highly efficient electrocatalysts capable of the oxygen‐reduction reaction (ORR) and the oxygen‐evolution reaction (OER). Herein, we report a facile sonication‐driven synthesis to deposit the molecular manganese vanadium oxide precursor [Mn4V4O17(OAc)3]3− on multiwalled carbon nanotubes (MWCNTs). Thermal conversion of this composite at 900 °C gives nanostructured manganese vanadium oxides/carbides, which are stably linked to the MWCNTs. The resulting composites show excellent electrochemical reactivity for ORR and OER, and significant reactivity enhancements compared with the precursors and a Pt/C reference are reported. Notably, even under harsh acidic conditions, long‐term OER activity at low overpotential is reported. In addition, we report exceptional activity of the composites for the industrially important Cl2 evolution from an aqueous HCl electrolyte. The new composite material shows how molecular deposition routes leading to highly active and stable multifunctional electrocatalysts can be developed. The facile design could in principle be extended to multiple catalyst classes by tuning of the molecular metal oxide precursor employed.
A DFT Study of the Modulation of the Antiaromatic and Open‐Shell Character of Dibenzo[a,f]pentalene by Employing Three Strategies: Additional Benzoannulation, BN/CC Isosterism, and Substitution
Authors: Baranac‐Stojanović Marija
Published: May 2019

Dibenzo[a,f]pentalene ([a,f]DBP) is a highly antiaromatic molecule having appreciable open‐shell singlet character in its ground state. In this work, DFT calculations at the B3LYP/6‐311+G(d,p) level of theory were performed to explore the efficiency of three strategies, that is, BN/CC isosterism, substitution, and (di)benzoannulation of [a,f]DBP, in controlling its electronic state and (anti)aromaticity. To evaluate the type and extent of the latter, the harmonic oscillator model of aromaticity (HOMA) and aromatic fluctuation (FLU) indices were used, along with the nucleus‐independent chemical shift NICS‐XY‐scan procedure. The results suggest that all three strategies could be employed to produce either the closed‐shell system or open‐shell species, which may be in the singlet or triplet ground state. Triplet states have been characterized as aromatic, which is in accordance with Baird's rule. All the singlet states were found to have weaker global paratropicity than [a,f]DBP. Additional (di)benzo fusion adds local aromatic subunit(s) and mainly retains the topology of the paratropic ring currents of the basic molecule. The substitution of two carbon atoms by the isoelectronic BN pair, or the introduction of substituents, results either in the same type and very similar topology of ring currents as in the parent compound, or leads to (anti)aromatic and nonaromatic subunits. The triplet states of all the examined compounds are also discussed.
Thiolated Graphene Oxide Nanoribbons as Templates for Anchoring Gold Nanoparticles: Two‐Dimensional Nanostructures for SERS
Authors: González‐Domínguez Jose M. , Colusso Andrea , Litti Lucio , Ostric Adrian , Meneghetti Moreno , Da Ros Tatiana
Published: May 2019

Graphene oxide nanoribbons (GONRs), obtained from the oxidative unzipping of carbon nanotubes, have been investigated as building blocks towards reaching active platforms in surface‐enhanced Raman scattering (SERS). The complete development of carbon nanomaterials is strongly related to the exploitation of their chemical versatility, so this work is focused on the positive effect that a specific chemical functionalization provides to the SERS effect when gold nanoparticles are used. The covalent derivatization of GONRs with terminal thiol groups boosts their interaction with different types of gold nanoparticles (namely, ‘naked’ or citrate‐stabilized), and the resulting two‐dimensional aggregates show an intense enhancement of the Raman scattering from the carbon nanostructures because of their two‐dimensional extended aggregation pattern. The SERS effect has been corroborated by theoretical calculations and a conceptual proof of SERS‐based sensing.
Learn lessons from a powerful provost
Authors: Hodges Dawn Z.
Published: May 2019

As a junior undergraduate student, I transferred to a private liberal arts college. When I was sitting in the upper‐class transfer students’ orientation, a young man who introduced himself to me as Charlie said, “See the man at the stage with the grey suit? When he turns around, he's going to be wearing a bow tie.” Well, Charlie was right. I later found out that Dr. Joe always wore bow ties.
It's all about process!
Authors: Sullivan Linda , Hall Enjie
Published: May 2019

Grievance, complaint, appeal … words that make a disability services provider's blood pressure rise. As students become more aware of their rights and the availability of academic accommodations, complaints at colleges and universities around the country have increased substantially. This is particularly true for health science programs due to the high‐stakes nature of these programs.
Research shows ‘new epidemic’ of students with anxiety
Authors: Sutton Halley
Published: May 2019

Reported rates of anxiety among college students have doubled since 2008, according to preliminary findings released by a team of researchers at the University of California, Berkeley. According to findings from the research team led by Richard Scheffler, a professor at the Goldman School of Public Policy and School of Public Health, the percentage of students aged 18 to 26 diagnosed with anxiety has increased from 10 percent in 2008 to 20 percent in 2018.
Harvest selection on multiple traits in the wild revealed by aquatic animal telemetry
Authors: Moland Even , Carlson Stephanie M. , Villegas‐Ríos David , Ree Wiig Jørgen , Moland Olsen Esben
Published: May 2019

Harvesting can have profound impacts on the ecology and evolution of marine populations. However, little is known about the strength and direction of fisheries‐induced selection acting on multiple traits in the wild. Here, we used acoustic telemetry to directly monitor individual behavior and fate in an intensively harvested species, the European lobster (Homarus gammarus, n = 100), in southern Norway. Overall, 24% of the tracked lobsters survived the two‐month harvest season within the study area. Our results indicated that local survival was not random with respect to phenotype. We found no clear support for fisheries‐induced selection acting directly on body size. However, lobsters with large crusher claws relative to their body size, typical of socially dominant individuals, appeared at higher risk of being captured in the conventional trap fishery. We also detected a fine‐scale spatial gradient in survival. After accounting for this gradient, individuals displaying larger home ranges were more likely to survive the harvest season. Finally, we found significant repeatabilities for lobster behavior on a monthly timescale, indicating that individual behavioral attributes tended to persist and may reflect personality. Our study therefore provides empirical support for the need to consider an evolutionary enlightened approach to fisheries management that considers the influence of harvest on multiple traits of target species.
Maxent modeling for predicting the spatial distribution of three raptors in the Sanjiangyuan National Park, China
Authors: Zhang Jingjie , Jiang Feng , Li Guangying , Qin Wen , Li Shengqing , Gao Hongmei , Cai Zhenyuan , Lin Gonghua , Zhang Tongzuo
Published: May 2019

Upland buzzard (Buteo hemilasius), Saker falcon (Falco cherrug), and Himalayan vulture (Gyps himalayensis) are three common large raptors in the Sanjiangyuan National Park (SNP), China's first national park. Among them, Upland buzzard and Saker falcon play a significant role in controlling plateau rodent populations and reducing the transmission of pathogens carried by rodents. The Himalayan vulture can provide services for the redistribution and recycling of nutrients in the ecosystem, and play an irreplaceable role in the celestial burial culture of Tibetans in China. Exploring their habitat suitability is important for the protection of the three raptors. Our research was based on the current distribution of Upland buzzard, Saker falcon, and Himalayan vulture that we had extensively surveyed in the Sanjiangyuan National Park from 2016 to 2017. Combined with the correlation analysis of environmental variables, we utilized maximum entropy model (MaxEnt) to evaluate and compare the habitat suitability of the three species in the Sanjiangyuan National Park. Elevation, climate, and human disturbance factors, which had direct or indirect effects on species survival and reproduction, were all included in the model. Among them, elevation was the most important environmental variables affecting the suitability of habitats of three species. Temperature‐related factor was another important predictor. The high (>60%) suitable habitat areas for Upland buzzard, Saker falcon, and Himalayan vulture were 73,017.63, 40,732.78, and 61,654.33 km2, respectively, accounted for 59.32%, 33.09%, and 50.08% of the Sanjiangyuan National Park and their total suitable area (i.e., the sum area of high and moderate habitats) reached 96.07%, 60.59%, and 93.70%, respectively. Besides, the three species have overlapping areas for the suitable habitats, which means that overlapping areas should be highly valued and protected. Therefore, understanding the distribution of suitable habitats of the three raptors can provide useful information and reasonable reference for us to put forward suggestions for their protection and regional management.
Synthesis of Thiazinoimidazoles by Lewis Acid–Catalyzed [3+3] Cycloaddition Reactions of Propargyl Alcohols with 2‐Mercaptoimidazoles
Authors: Mishima Naoya , Ogawa Takahiro , Tanabe Genzoh , Muraoka Osamu , Wasada Hiroaki , Hatae Noriyuki , Yoshimatsu Mitsuhiro
Published: May 2019

The unique ytterbium‐catalyzed generation of sulfur‐ and selenium‐substituted propargylic and allenic cations and their reactions with 2‐mercaptoimidazole derivatives were described. The regioselective [3+3] annulation reactions proceeded to give a wide variety of S,N‐acetal‐containing bicyclic and tricyclic thiazinoimidazoles in good to high yields. Treatment of thiazinoimidazoles with LDA readily underwent ring contraction to afford thiazolobenzimidazoles. Deselenenylation and successive functionalization broaden the scope of accessible thiazinoimidazoles.
Chemical Insights into the Anchinopeptolide Series
Authors: Bastos Lemos Silva Siguara , Beniddir Mehdi A. , Gallard Jean‐François , Poupon Erwan , Thomas Olivier P. , Evanno Laurent
Published: May 2019

The chemical composition of the marine sponge Phorbas tenacior was investigated in depth. The anchinopeptolides A–D bearing a central pyrrolidinone were isolated together with a new congener named anchinopeptolide E corresponding to an epimer of anchinopeptolide C. The relative configuration of the central core of anchinopeptolide E was determined by extensive NMR analyses. Additionally, the previously isolated cyclobutane derivative cycloanchinopeptolide C was not detected from the sponge extract but could be synthesised by a photoinduced intramolecular [2+2] cycloaddition giving convincing evidence for its artefactual origin.
Palladium‐Catalyzed Carbonylative Synthesis of Benzyl Benzoates Employing Benzyl Formates as Both CO Surrogates and Benzyl Alcohol Sources
Authors: Lai Ming , Qi Xinxin , Wu Xiao‐Feng
Published: May 2019

An efficient and convenient palladium‐catalyzed carbonylation reaction for the synthesis of benzyl benzoates from aryl bromides has been developed. Benzyl formates have been explored as a new type of efficient and useful CO sources and also reaction partners. A wide range of benzyl benzoates was obtained in good to excellent yields.