bluuebunny/crossref_metadata_2025 huggingface dataset:
САВРЕМЕНА ОСНОВНА ШКОЛА ИЗМЕЂУ ДРУШТВЕНИХ ОЧЕКИВАЊА И РЕАЛНОСТИ КРИЗЕ ТЕОРИЈЕ И ПРАКСЕ ВАСПИТАЊА И ОБРАЗОВАЊА
Authors: Спасојевић Перо , Цвјетковић Марица , Спасојевић Влатка
Published: January 2019

Очекивања од основне школе као институције друштва, безсваке сумње са најважнијом друштвеном мисијом васпитања и образовања,фундаменталног „животног оспособљавања“ и дјеловања на развој личности дјецеза „здраво друштво“, све више су у знаку сумњи и оспоравања, са посљедицама којеуказују на озбиљну кризу теорије и праксе школа. Узроци такве климе, којом се овакриза дуже вријеме само продубљује, посебно у односима између школе и породице,разноврсни су и комплексни, захтијевају брз и јасан одговор школске педагогије исвих научних дисциплина које се баве школом, захтијевају да се истражи, у којојмјери је одржив сасвим јасан апологетски однос према школском насљеђу итрадицији и какве су рефлексије бројних и вјероватно некритички и рђавоприпремљених промјена који ову кризу увећавају. Међу евидентне слабости школенајчешће се убрајају занемаривање статуса ученика у школском раду, са јасномдилемом да ли је он „актер школског рада“ или објекат на који су усмјерене мањевише ауторитарне педагошке мјере и поступци по избору одраслих, родитеља инаставника, прије свега, да ли се на „школске дужности“ гледа из перспективедјетета и његових аутентичних могућности, или школа покушава своју „немогућумисију“, да укине „неједнакост прилика“ (Груден, З. Груден, В., 2006.) у којима живеи са којима долазе у школу. Осим тога, указује се често на „изолованост родитељаод школе“, негирање њихових компетенција да се баве васпитањем и образовањемако дјеца већ иду у школу, што доводи до дисфункционалних односа, маргинализацијењихових објективних моћи дјеловања на квалитетнију школу, у којој се родитељиукључују са својим идејама, прије свега, са становишта користи за своје дијете ињегов развојни просперитет. Није ли, на тај начин, школа претјерано заснована на„мисији светости знања“, није ли криза генерисана инертношћу или непостојањемсигурне теорије школе и школске педагогије према овим појавама у пракси? Овај радпосвећен је могућим одговорима на ове изазове.
ПОЗИЦИЈЕ УЧИТЕЉА У КОМБИНОВАНИМ ОДЈЕЉЕЊИМА
Authors: Милић Сања , Пердан Маја
Published: January 2019

Комбинована одјељења стварају потешкоће у васпитно-образовном процесу, све је мање ученика који похађају наставу у овим одјељењимаа све више проблема који утичу на организацију и реализацију наставног рада. Подоласку у комбиновано одјељење, учитељ преузима велику одговорност јерпланирање и припремање васпитно-образовног рада спада у најважнијекомпетенције, и од његове организације и креативности зависи успјех ученика. Овајрад се бави истраживањем позицијe учитеља у комбинованим одјељењима, како ина који начин организују рад, да ли се стручно усавршавају, у каквим условима радеи да ли су задовољни.
РАЗВОЈ КРЕАТИВНОГ МИШЉЕЊА ПРЕДШКОЛАЦА У ПЕТЕРБУРГУ И БЕОГРАДУ – УПОРЕДНА АНАЛИЗА
Authors: Јањевић Поповић Весна , Филиповић Сања , Туник Елена
Published: January 2019

Један од начина да се скрене пажња на потребу систематског развијања креативног изражавања деце је да се анализира тренутна ситуација у овом региону. Примена Вилијамс теста креативности на популацију предшколске деце омогућила је нове методе праћења развоја деце. Циљ истраживања је да се упореде резултати тестирања деце из Београда и Петеребурга користећи Вилијамс тест креативности. Истраживање је показало статистички значајне разлике у резултатима између деце из Београда и деце из области Петербурга у корист деце из Београда. Остаје отворено питање даљег истраживања и поређења концепција програма рада предшколских установа.
ЕФИКАСНОСТ НАСТАВЕ У МЛАЂЕМ ШКОЛСКОМ УЗРАСТУ У СВЈЕТЛУ ИЗБОРА МЕТОДА И РАЗВОЈА КОМПЕТЕНЦИЈА УЧЕНИКА
Authors: Спасојевић Влатка
Published: January 2019

Почетком ХХI вијека постало је јасно да дидактицизиране школе не могу задовољити потребе и интересовања ученика, прије свега због форсирања трансмисивних и меморијско-репродуктивних функција наставе. У учећој цивилизацији таква школа почиње да губи примат у односу на друге видове учења и подршке развоја. Овај рад посвећен је анализи метода подстицања и спречавања, с циљем да се освијетле могућности јачања васпитне функције наставе. Ријеч је о истраживачкој провјери утицаја метода подстицања и спречавања на развој компетенција ученика за ХХI вијек, са намјером да се утврди постоји ли узрочнопосљедична повезаност између ставова ученика о томе које методе користе наставници и како се то одражава на ефикасност рада на наставном часу. Доминантне методе истраживања у раду су метода теоријске анализе и синтезе и сервеј метода, а значај истраживања је у освјетљавању нових начина педагошког рада и припремања ученика за стицање знања, вјештина и навика у виду компетенција за вријеме које долази.
САВРЕМЕНИ ПРИСТУП САДРЖАЈИМА СЛУШАЊА ИНСТРУМЕНТАЛНЕ МУЗИКЕ У МЛАЂИМ РАЗРЕДИМА ОСНОВНЕ ШКОЛЕ
Authors: Спасојевић-Стојановић Гордана
Published: January 2019

Савремено дијете окружено је разноврсним жанровима и врстама музике које често не садрже хуману компоненту потребну за правилан естетски развој личности. Настава музичке културе у млађим разредима основне школе, и поред добрих програмских садржаја слушања музике, не утиче довољно на развијање и његовање правилног музичког укуса и естетске културе. У овом раду бавимо се новим теоријским и практичним начинима презентације садржаја слушања инструменталне музике с циљем што боље мотивације ученика за слушање вриједних музичких остварења. Активно слушање програмске и апсолутне музике подстиче индивидуални емоционални доживљај, који ученици исказују кроз разноврсне видове стваралачког и креативног изражавања. Креативни приступ садржајима слушања музике допринијеће обогаћењу програмске и методичке концепције наставе музичке културе у млађим разредима основне школе. Тиме ће утицај наставе музике у подстицању интересовања и потреба савременог дјетета за музичку умјетност бити већи.
ПРОБЛЕМСКИ ЗАДАЦИ У ФУНКЦИЈИ ИНТЕГРАЦИЈЕ НАСТАВЕ МАТЕМАТИКЕ У КОМБИНОВАНИМ ОДЈЕЉЕЊИМА
Authors: Милинковић Драгица
Published: January 2019

Савремена настава математике базичног циклуса образовања,као један од темељних циљева поставља стицање практичних математичких знања,неопходних за разумијевање и успјешно коришћење свакодневних информација, и, ускладу с тим, активан стваралачки приступ проблемима из реалног живота. Имајућиу виду све већи број комбинованих oдјељења у Републици Српској у којима суинтегрисана два, три, четири или пет разреда, те захтјеве савремене школе у погледустицања цјеловитих знања, неопходно је, осим унутарподручне и међуподручнемеђупредметне интеграције на нивоу разреда, програмске садржаје математике,када год је могуће, интегрисати на нивоу одјељења. Тиме се успостављаматематичка комуникација међу ученицима свих разреда која доприноси усвајању,савладавању и примјени нових математичких концепата, блиских узрасном нивоу, урјешавању истих животних проблема. У том смислу, значајан фактор предметнеинтеграције у настави комбинованих одјељења представљају проблемски задаци којитематиком и садржајем одражавају актуелна друштвена догађања, аквантитативним подацима и језичком формулацијом се прилагођавају програмскимциљевима, задацима и очекиваним исходима учења интегрисаних разреда. Оваквимприступом настави математике у комбинованим одјељењима се остварујеистовремена активна комуникација математичким језиком свих учесника унаставном процесу, а блиским, интересантним и мотивишућим проблемскимситуацијама омогућава ученицима, развоју прилагођено, искуствено аутентичноучење.
Mycobacterium tuberculosis SatS is a chaperone for the SecA2 protein export pathway
Authors: Miller Brittany K , Hughes Ryan , Ligon Lauren S , Rigel Nathan W , Malik Seidu , Anjuwon-Foster Brandon R , Sacchettini James C , Braunstein Miriam
Published: January 2019

The SecA2 protein export system is critical for the virulence of Mycobacterium tuberculosis. However, the mechanism of this export pathway remains unclear. Through a screen for suppressors of a secA2 mutant, we identified a new player in the mycobacterial SecA2 pathway that we named SatS for SecA2 (two) Suppressor. In M. tuberculosis, SatS is required for the export of a subset of SecA2 substrates and for growth in macrophages. We further identify a role for SatS as a protein export chaperone. SatS exhibits multiple properties of a chaperone, including the ability to bind to and protect substrates from aggregation. Our structural studies of SatS reveal a distinct combination of a new fold and hydrophobic grooves resembling preprotein-binding sites of the SecB chaperone. These results are significant in better defining a molecular pathway for M. tuberculosis pathogenesis and in expanding our appreciation of the diversity among chaperones and protein export systems.
High-throughput synapse-resolving two-photon fluorescence microendoscopy for deep-brain volumetric imaging in vivo
Authors: Meng Guanghan , Liang Yajie , Sarsfield Sarah , Jiang Wan-chen , Lu Rongwen , Dudman Joshua Tate , Aponte Yeka , Ji Na
Published: January 2019

Optical imaging has become a powerful tool for studying brains in vivo. The opacity of adult brains makes microendoscopy, with an optical probe such as a gradient index (GRIN) lens embedded into brain tissue to provide optical relay, the method of choice for imaging neurons and neural activity in deeply buried brain structures. Incorporating a Bessel focus scanning module into two-photon fluorescence microendoscopy, we extended the excitation focus axially and improved its lateral resolution. Scanning the Bessel focus in 2D, we imaged volumes of neurons at high-throughput while resolving fine structures such as synaptic terminals. We applied this approach to the volumetric anatomical imaging of dendritic spines and axonal boutons in the mouse hippocampus, and functional imaging of GABAergic neurons in the mouse lateral hypothalamus in vivo.
A Tournaisian (earliest Carboniferous) conglomerate-preserved non-marine faunal assemblage and its environmental and sedimentological context
Authors: Clack Jennifer A. , Bennett Carys E. , Davies Sarah J. , Scott Andrew C. , Sherwin Janet E. , Smithson Timothy R.
Published: January 2019

A conglomerate bed from the Tournaisian Ballagan Formation of Scotland preserves a rich array of vertebrate and other nonmarine fossils providing an insight into the wider ecosystem and paleoenvironment that existed during this pivotal stage of Earth history. It challenges hypotheses of a long-lasting post-extinction trough following the end-Devonian extinction event. The fauna recovered includes a wide size range of tetrapods, rhizodonts, and dipnoans, from tiny juveniles or small-bodied taxa up to large adults, and more than one taxon of each group is likely. Some fauna, such as actinopterygians and chondrichthyans, are rare as macrofauna but are better represented in the microfossil assemblage. The fauna provides evidence of the largest Carboniferous lungfish ever found. The specimens are preserved in a localized, poorly-sorted conglomerate which was deposited in the deepest part of a river channel, the youngest of a group of channels. In addition to the fossils (micro- and macro-), the conglomerate includes locally-derived clasts of paleosols and other distinctive elements of the surrounding floodplains. Charcoal fragments represent small woody axes and possible larger trunk tissue from arborescent pteridosperms. Preservation of the fossils indicates some aerial exposure prior to transport, with abrasion from rolling. The findings presented here contrast with other published trends in vertebrate size that are used to interpret a reduction in maximum sizes during the Tournaisian. The richness of the fauna runs counter to the assumption of a depauperate nonmarine fauna following the end-Devonian Hangenberg event, and charcoal content highlights the occurrence of fire, with the requisite levels of atmospheric oxygen during that stage.
Isolation and identification of marine strains ofStenotrophomona maltophiliawith high chitinolytic activity
Authors: Salas-Ovilla Roger , Gálvez-López Didiana , Vázquez-Ovando Alfredo , Salvador-Figueroa Miguel , Rosas-Quijano Raymundo
Published: January 2019

Chitin is the second most abundant organic compound in nature and represents a rich carbon and nitrogen source that is primarily transformed by bacterial communities. Bacteria capable of gradually hydrolyzing chitin into N-acetylglucosamine monomers can have applications in the transformation of residues from shrimp and other crustaceans. The objective of the present study was to isolate, characterize and identify microorganisms with high chitinolytic activity. These microorganisms were isolated and characterized based on macro- and microscopic morphological traits. Strains were selected on colloidal chitin agar medium primarily based on a hydrolysis halo larger than 2 mm and a growing phase no longer than 6 days. Secondary selection consisted of semi-quantitative evaluation of chitinolytic activity with a drop dilution assay. From the above, ten strains were selected. Then, strain-specific activity was evaluated. The B4 strain showed the highest specific activity, which was 6,677.07 U/mg protein. Molecular identification indicated that the isolated strains belong to the speciesStenotrophomonas maltophilia.
The role of Central American barriers in shaping the evolutionary history of the northernmost glassfrog,Hyalinobatrachium fleischmanni(Anura: Centrolenidae)
Authors: Mendoza Angela M. , Bolívar-García Wilmar , Vázquez-Domínguez Ella , Ibáñez Roberto , Parra Olea Gabriela
Published: January 2019

The complex geological history of Central America has been useful for understanding the processes influencing the distribution and diversity of multiple groups of organisms. Anurans are an excellent choice for such studies because they typically exhibit site fidelity and reduced movement. The objective of this work was to identify the impact of recognized geographic barriers on the genetic structure, phylogeographic patterns and divergence times of a wide-ranging amphibian species,Hyalinobatrachium fleischmanni. We amplified three mitochondrial regions, two coding (COI and ND1) and one ribosomal (16S), in samples collected from the coasts of Veracruz and Guerrero in Mexico to the humid forests of Chocó in Ecuador. We examined the biogeographic history of the species through spatial clustering analyses (Geneland and sPCA), Bayesian and maximum likelihood reconstructions, and spatiotemporal diffusion analysis. Our data suggest a Central American origin ofH. fleischmanniand two posterior independent dispersals towards North and South American regions. The first clade comprises individuals from Colombia, Ecuador, Panama and the sister speciesHyalinobatrachium tatayoi; this clade shows little structure, despite the presence of the Andes mountain range and the long distances between sampling sites. The second clade consists of individuals from Costa Rica, Nicaragua, and eastern Honduras with no apparent structure. The third clade includes individuals from western Honduras, Guatemala, and Mexico and displays deep population structure. Herein, we synthesize the impact of known geographic areas that act as barriers to glassfrog dispersal and demonstrated their effect of differentiatingH. fleischmanniinto three markedly isolated clades. The observed genetic structure is associated with an initial dispersal event from Central America followed by vicariance that likely occurred during the Pliocene. The southern samples are characterized by a very recent population expansion, likely related to sea-level and climatic oscillations during the Pleistocene, whereas the structure of the northern clade has probably been driven by dispersal through the Isthmus of Tehuantepec and isolation by the Motagua–Polochic–Jocotán fault system and the Mexican highlands.
Analysis of the complete genome sequence of a marine-derived strainStreptomycessp. S063 CGMCC 14582 reveals its biosynthetic potential to produce novel anti-complement agents and peptides
Authors: Chen Liang-Yu , Cui Hao-Tian , Su Chun , Bai Feng-Wu , Zhao Xin-Qing
Published: January 2019

Genome sequences of marine streptomycetes are valuable for the discovery of useful enzymes and bioactive compounds by genome mining. However, publicly available complete genome sequences of marine streptomycetes are still limited. Here, we present the complete genome sequence of a marine streptomyceteStreptomycessp. S063 CGMCC 14582. Species delineation based on the pairwise digital DNA-DNA hybridization and genome comparison ANI (average nucleotide identity) value showed thatStreptomycessp. S063 CGMCC 14582 possesses a unique genome that is clearly different from all of the other available genomes. Bioactivity tests showed thatStreptomycessp. S063 CGMCC 14582 produces metabolites with anti-complement activities, which are useful for treatment of numerous diseases that arise from inappropriate activation of the human complement system. Analysis of the genome reveals no biosynthetic gene cluster (BGC) which shows even low similarity to that of the known anti-complement agents was detected in the genome, indicating thatStreptomycessp. S063 CGMCC 14582 may produce novel anti-complement agents of microbial origin. Four BGCs which are potentially involved in biosynthesis of non-ribosomal peptides were disrupted, but no decrease of anti-complement activities was observed, suggesting that these four BGCs are not involved in biosynthesis of the anti-complement agents. In addition, LC-MS/MS analysis and subsequent alignment through the Global Natural Products Social Molecular Networking (GNPS) platform led to the detection of novel peptides produced by the strain.Streptomycessp. S063 CGMCC 14582 grows rapidly and is salt tolerant, which benefits efficient secondary metabolite production via seawater-based fermentation. Our results indicate thatStreptomycessp. S063 has great potential to produce novel bioactive compounds, and also is a good host for heterologous production of useful secondary metabolites for drug discovery.
Polyphasic evaluation of key cyanobacteria in biocrusts from the most arid region in Europe
Authors: Roncero-Ramos Beatriz , Muñoz-Martín M. Ángeles , Chamizo Sonia , Fernández-Valbuena Lara , Mendoza Diego , Perona Elvira , Cantón Yolanda , Mateo Pilar
Published: January 2019

Cyanobacteria are key microbes in topsoil communities that have important roles in preventing soil erosion, carbon and nitrogen fixation, and influencing soil hydrology. However, little is known regarding the identity and distribution of the microbial components in the photosynthetic assemblages that form a cohesive biological soil crust (biocrust) in drylands of Europe. In this study, we investigated the cyanobacterial species colonizing biocrusts in three representative dryland ecosystems from the most arid region in Europe (SE Spain) that are characterized by different soil conditions. Isolated cyanobacterial cultures were identified by a polyphasic approach, including 16S rRNA gene sequencing, phylogenetic relationship determination, and morphological and ecological habitat assessments. Three well-differentiated groups were identified: heterocystous-cyanobacteria (Nostoc commune,Nostoc calcicola,Tolypothrix distortaandScytonema hyalinum), which play an important role in N and C cycling in soil; nonheterocystous bundle-forming cyanobacteria (Microcoleus steenstrupii,Trichocoleus desertorum, andSchizothrixcf. calcicola); and narrow filamentous cyanobacteria (Leptolyngbya frigidaandOculatella kazantipica), all of which are essential genera for initial biocrust formation. The results of this study contribute to our understanding of cyanobacterial species composition in biocrusts from important and understudied European habitats, such as the Mediterranean Basin, a hotspot of biodiversity, where these species are keystone pioneer organisms.
Highly Sensitive, Low Voltage Operation, and Low Power Consumption Resistive Strain Sensors Based on Vertically Oriented Graphene Nanosheets
Authors: Jiang Qianqing , Tang Chengchun , Wang Huaping , Yang Jie , Li Junjie , Gu Changzhi , Yu Gui
Published: January 2019

Flexible and stretchable electronics are essential module of mobile wearable devices, soft human–machine interfaces, and also e‐skin on biomedical prostheses and biorobotics. Strain sensors, as one of the major part of flexible electronics, have been extensively studied recently. When being used for mobile and long‐term applications, low power consumption and low operation voltage beside high sensitivity and fast response of the sensors are required. Easy integration is also an important aspect to build an internet of things. Here, resistive strain sensors with a maximum gauge factor of 150, a fast response time of about 10 ms, a low operation voltage of 20 mV, and a low power consumption of <8 µW, are demonstrated by introducing easily patternable vertically oriented graphene nanosheets (VGs film) as the sensing material. Ultrasmall strain of 0.07% can be detected with VGs film patterned into 200 µm × 200 µm square array. It is the special structure of the VGs film with a combination of an underlying buffer layer and vertically oriented nanosheets upon it that ensures both the high sensitivity and the low power consumption. To demonstrate the capacities of the sensor, the sensor was applied to monitor the human artery pulses.
Universal Scaling Law for Methane Capture Quantity in Metal–Organic Frameworks
Authors: Lin Haoxiang , Cai Shuhong , Zhu Xi
Published: January 2019

In this work, a universal scaling law for the methane gas capture quantity in metal–organic frameworks (MOFs) structure is provided. The methane–MOF adsorption events are catalogued into energy and space scenario individually. The energy factor includes three types of energy forces for both bonding and non‐bonding interactions in variant type of MOFs structures: that is, 1) metal–gas interactions, 2) heteroatom–gas bonds, and 3) non‐bonding interactions, including Van der Waals as well as Coulomb interactions. The subspace factor includes: 1) geometrical void fraction volume, 2) surface area, and 3) the limiting local pore size. Under this catalogue, more than 65 000 types of MOFs with relative high gas capture are studied; a linear scaling law can be approached via the group combination of the energy and space factor. Moreover, the decomposed scaling law indicates that for the exploring of high gas storage MOFs structure, the design of spatial geometry takes more importance than the chemical bonding of gas–MOFs interactions. The linear scaling works for other gases, like nitrogen and carbon dioxide as well. This work provides a qualitative understanding for the design of MOFs materials for the gas capture utility.
Efficient Bifunctional Polyalcohol Oxidation and Oxygen Reduction Electrocatalysts Enabled by Ultrathin PtPdM (M = Ni, Fe, Co) Nanosheets
Authors: Lai Jianping , Lin Fei , Tang Yonghua , Zhou Peng , Chao Yuguang , Zhang Yelong , Guo Shaojun
Published: January 2019

Despite intense research in past decades, the development of high‐performance bifunctional catalysts for direct ethylene glycol or glycerol oxidation reaction (EGOR or GOR) and oxygen reduction reaction (ORR) remains a grand challenge in realizing fuel‐cell technologies for portable electronic devices and fuel‐cell vehicle applications. Here, a general method is reported for controllable synthesis of a class of ultrathin multimetallic PtPdM (M = Ni, Fe, Co) nanosheets (NSs) with a thickness of only 1.4 nm by coreduction of metal precursors in the presence of CO and oleylamine. With the optimized composition and components, ultrathin Pt32Pd48Ni20 NSs exhibit the highest electrocatalytic activity for EGOR, GOR, and ORR among all different ultrathin PtPdM NSs, ultrathin PtPd NSs, and the commercial catalysts. The mass activities of ultrathin Pt32Pd48Ni20 NSs for EGOR, GOR, and ORR are 7.7, 5.4, and 7.7 times higher respectively than a commercial catalyst, and they are the most efficient nanocatalysts ever reported for EGOR/GOR. The ultrathin PtPdNi NSs are also very stable for EGOR/GOR/ORR. It is further demonstrated that these ultrathin multimetallic NSs can be readily generalized to other sensor‐related electrocatalysis system such as high‐sensitivity electrochemical detection of H2O2.
Differences in novel food response betweenPongoandPan
Authors: Forss Sofia Ingrid Fredrika , Motes‐Rodrigo Alba , Hrubesch Christine , Tennie Claudio
Published: January 2019

The diversity of great ape diets requires behavioral flexibility. Consequently, the exploration of potentially novel food sources is supposedly beneficial, but simultaneously, apes show high neophobia to prevent harmful and poisonous food intake. Social information, such as presence of group members or observations of non‐naïve, experienced individuals have been demonstrated to affect the acceptance of novel food items in primates. Sociality may have evolutionary effects on the response of apes to novel foods. Here we assess thesocial information hypothesis, which predicts that selection favors higher neophobia in species where social information is abundant. We report the results from 134 great apes housed in multiple facilities from four closely related species that naturally differ in their degree of sociality:Pongo pygmaeus,Pongo abelii,Pan troglodytesandPan paniscus. We examined individuals’ reactions to novel foods when alone, which enabled us to detect any inherent differences and revealed significant distinctions between species. Chimpanzees and bonobos, that are naturally exposed to higher amounts of social information, were less likely to consume novel foods alone (showed higher neophobia) than the two more solitary orangutan species. Chimpanzees were especially cautious and showed higher explorative behaviors before tasting novel food than other species. Age influenced neophobia as younger individuals of all species took longer to taste novel foods than adults did.
Inhibitor‐Induced Dimerization of an Essential Oxidoreductase from African Trypanosomes
Authors: Wagner Annika , Le Thien Anh , Brennich Martha , Klein Philipp , Bader Nicole , Diehl Erika , Paszek Daniel , Weickhmann A. Katharina , Dirdjaja Natalie , Krauth‐Siegel R. Luise , Engels Bernd , Opatz Till , Schindelin Hermann , Hellmich Ute A.
Published: January 2019

Trypanosomal and leishmanial infections claim tens of thousands of lives each year. The metabolism of these unicellular eukaryotic parasites differs from the human host and their enzymes thus constitute promising drug targets. Tryparedoxin (Tpx) from Trypanosoma brucei is the essential oxidoreductase in the parasite's hydroperoxide‐clearance cascade. In vitro and in vivo functional assays show that a small, selective inhibitor efficiently inhibits Tpx. With X‐ray crystallography, SAXS, analytical SEC, SEC‐MALS, MD simulations, ITC, and NMR spectroscopy, we show how covalent binding of this monofunctional inhibitor leads to Tpx dimerization. Intra‐ and intermolecular inhibitor–inhibitor, protein–protein, and inhibitor–protein interactions stabilize the dimer. The behavior of this efficient antitrypanosomal molecule thus constitutes an exquisite example of chemically induced dimerization with a small, monovalent ligand that can be exploited for future drug design.
Facile Access to an NHC‐Coordinated Silicon Ring Compound with a Si=N Group and a Two‐Coordinate Silicon Atom
Authors: Keuter Jan , Hepp Alexander , Mück‐Lichtenfeld Christian , Lips Felicitas
Published: January 2019

Reaction of the bicyclo[1.1.0]tetrasilatetraamide Si4{N(SiMe3)Dipp}4 1 (Dipp=2,6‐diisopropylphenyl) with 5 equiv of the N‐heterocyclic carbene NHCMe4 (1,3,4,5‐tetramethylimidazol‐2‐ylidene) affords a bifunctional carbene‐coordinated four‐membered‐ring compound with a Si=N group and a two‐coordinate silicon atom Si4{N(SiMe3)Dipp}2(NHCMe4)2(NDipp) 2. When 2 reacts with 0.25 equiv sulfur (S8), two sulfur atoms add to the divalent silicon atom in plane and perpendicular to the plane of the Si4 ring, which confirms the silylone character of the two‐coordinate silicon atom in 2.
Enhanced breakdown strength and electrical tree resistance properties of MMT/SiO2/LDPE multielement composites
Authors: Zhang Xiaohong , Shi Zexiang , Ma Lisha , Gao Junguo , Guo Ning
Published: January 2019

Montmorillonite (MMT)/low‐density polyethylene (LDPE) nanocomposites have excellent partial discharge resistance and electrical tree resistance compared with pure LDPE. However, the MMT/LDPE nanocomposites have low breakdown strength due to the poor compatibility between nano‐MMT and LDPE. In order to improve the breakdown strength of the MMT/LDPE composites without changing the LDPE matrix, an MMT/SiO2/LDPE multielement composite was prepared by melt blending, and its breakdown strength and electrical tree resistance properties were investigated. The results show that the MMT/SiO2/LDPE multielement composite has excellent breakdown strength and electrical tree resistance properties compared with the MMT/LDPE composite. The reasons for the excellent insulation properties of the MMT/SiO2/LDPE multielement composites were analyzed by exploring the effects of MMT and SiO2 on the microstructure and trap characteristics of LDPE. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47364.
Tuning the interphase adhesion in high‐density polyethylene–silica nanocomposites with ionic liquids
Authors: Donato Katarzyna Z. , Donato Ricardo K. , Zhigunov Alexander , Mauler Raquel S. , Schrekker Henri S.
Published: January 2019

This work addresses the use of ionic liquids (ILs) as multifunctional additives in the formation of high‐density polyethylene (HDPE)/sol–gel silica nanocomposites via the melt‐mixing process. Different approaches for nanocomposite formation were studied and compared, including (1) silica modification with ILs during the sol–gel process and further addition into the polymer matrix, (2) reactive mixing in which silica‐IL filler was formed in situ, and (3) direct IL application in the melt‐mixing chamber with nonmodified silica xerogel and HDPE. The nanocomposites were characterized by thermogravimetric analyses, differential scanning calorimetry, scanning electron microscopy, dynamic thermomechanical analyses, transmission electron microscopy, and contact angle analyses. To improve the silica compatibilization with HDPE, we investigated imidazolium ILs that presented at least one nonpolar ionic counterpart. This permitted control of the silica structure, morphology, dispersion, and interfacial interactions, providing enhancements in thermomechanical properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47366.
Doubly N‐Confused Calix[6]phyrin Bis‐Organopalladium Complexes: Photostable Triplet Sensitizers for Singlet Oxygen Generation
Authors: Pushpanandan Poornenth , Won Dong‐Hoon , Mori Shigeki , Yasutake Yuhsuke , Fukatsu Susumu , Ishida Masatoshi , Furuta Hiroyuki
Published: January 2019

Triplet photosensitizers that generate singlet oxygen efficiently are attractive for applications such as photodynamic therapy (PDT). Extending the absorption band to a near‐infrared (NIR) region (700 nm≈) with reasonable photostability is one of the major demands in the rational design of such sensitizers. We herein prepared a series of mono‐ and bis‐palladium complexes (1‐Pd‐H2, 2‐Pd‐H2, 1‐Pd‐Pd, and 2‐Pd‐Pd) based on modified calix[6]phyrins as photosensitizers for singlet oxygen generation. These palladium complexes showed intense absorption profiles in the visible‐to‐NIR region (500–750 nm) depending on the number of central metals. Upon photoirradiation in the presence of 1,5‐dihydroxynaphthalene (DHN) as a substrate for reactive oxygen species, the bis‐palladium complexes generated singlet oxygen with high efficiency and excellent photostability. Singlet oxygen generation was confirmed from the characteristic spectral feature of the spin trapped complex in the EPR spectrum and the intact 1O2 emission at 1270 nm.
Polymorphic Pure Organic Luminogens with Through‐Space Conjugation and Persistent Room‐Temperature Phosphorescence
Authors: Zhang Tingting , Zhao Zihao , Ma Huili , Zhang Yongming , Yuan Wang Zhang
Published: January 2019

Pure organic luminogens with persistent room‐temperature phosphorescence (p‐RTP) have attracted increasing attention owing to their vital significance and potential applications in security inks, bioimaging, and photodynamic therapy. Previously reported p‐RTP luminogens normally possessed through‐bond conjugation. In this work, we report a pure organic luminogen, AN‐MA, the Diels–Alder cycloaddition adduct of anthracene (AN) and maleic anhydride (MA), which possesses isolated phenyl groups and an anhydride moiety. AN‐MA exhibits aggregation‐enhanced emission (AEE) characteristics with efficiency of approximately 2 % and up to 8.5 % in solution and crystals, respectively. Two polymorphs of AN‐MA were readily obtained that were able to generate UV emission from individual phenyl rings together with bright blue emission owing to the effective through‐space conjugation. Moreover, p‐RTP with a lifetime of up to approximately 1.6 s was obtained in the crystals. These results not only reveal a new system with both fluorescence and RTP dual emission but also suggest an alternative through‐space conjugation strategy towards pure organic p‐RTP luminogens with tunable emissions.
Beryllium Halide Complexes Incorporating Neutral or Anionic Ligands: Potential Precursors for Beryllium Chemistry
Authors: Paparo Albert , Jones Cameron
Published: January 2019

Reactions of the beryllium dihalide complexes [BeX2(OEt2)2] (X=Br or I) with N,N,N′,N′‐tetramethylethylenediamine (TMEDA), a series of diazabutadienes, or bis(diphenylphosphino)methylene (DPPM) have yielded the chelated complexes, [BeX2(TMEDA)], [BeX2{(RN=CH)2}] (R=tBu, mesityl (Mes), 2,6‐diethylphenyl (Dep) or 2,6‐diisopropylphenyl (Dip)), and the non‐chelated system, [BeI2(κ1‐P‐DPPM)2]. Reactions of lithium or potassium salts of a variety of β‐diketiminates have given both three‐coordinate complexes, [{HC(RCNAr)2}BeX] (R=H or Me; Ar=Mes, Dep or Dip; X=Br or I); and four‐coordinate systems, [{HC(MeCNPh)2}BeBr(OEt2)] and [{HC(MeCNDip)(MeCNC2H4NMe2}BeI]. Alkali metal salts of ketiminate, guanidinate, boryl/phosphinosilyl amide, or terphenyl ligands, lead to dimeric [{BeI{μ‐[(OCMe)(DipNCMe)]CH}}2], and monomeric [{iPr2NC(NMes)2}BeI(OEt2)], [κ2‐N,P‐{(HCNDip)2B}(PPh2SiMe2)NBeI(OEt2)] and [{C6H3Ph2‐2,6}BeBr(OEt2)], respectively. Compound [{HC(MeCNPh)2}BeBr(OEt2)] undergoes a Schlenk redistribution reaction in solution, affording the homoleptic complex, [{HC(MeCNPh)2}2Be]. The majority of the prepared complexes have been characterized by X‐ray crystallography and multi‐nuclear NMR spectroscopy. The structures and stability of the complexes are discussed, as is their potential for use as precursors in poorly developed low oxidation state beryllium chemistry.
Effect of Surface Chemical Bonding States on Lithium Intercalation Properties of Surface‐Modified Lithium Cobalt Oxide
Authors: Hata Jun‐Ichi , Hirayama Masaaki , Suzuki Kota , Dupré Nicolas , Guyomard Dominique , Kanno Ryoji
Published: January 2019

Understanding interfacial reactions between surface‐modified lithium intercalation cathodes and organic electrolytes facilitates the design of highly functional cathodes for lithium‐ion batteries. Here, the chemical bonding state between a LiCoO2 cathode and a ZrO2−x surface layer is controlled by pulsed arc plasma deposition using different ion energies. The lithium intercalation properties and interfacial structure changes are subsequently analyzed. The Zr−O−Co‐modified surface formed by interaction between ZrO2−x and LiCoO2 provides superior cycle stability under high‐voltage operation (2.8–4.5 V). X‐ray photoemission spectroscopy clarifies that the Zr−O−Co surface forms highly adhesive ZrOxFy as a cathode electrolyte interphase (CEI). The chemical bonding state at the ZrO2−x/LiCoO2 interface affects the reactivity of ZrO2−x with electrolyte species as well as the architecture of the CEI, which may determine the cell performances of lithium intercalation cathodes.
Less willing to pay but more willing to buy: How the elicitation method impacts the valuation of a promotion
Authors: Lu Zoe Y. , Hsee Christopher K.
Published: January 2019

Willingness to pay (WTP—how much one is willing to pay for something) and willingness to buy (WTB—whether one is willing to buy something at a given price) are two common methods to elicit valuations and normatively should yield the same valuation order between two options. However, this research finds that WTP and WTB can yield opposite valuation orders between the regular offer and the promotional offer of a product. Specifically, it demonstrate that, (a) if the valuation of a product is only elicited with WTP, consumers value the product less when it is offered with a price promotion than when it is not; (b) if the valuation of a product is only elicited with WTB, consumers value the product more when it is offered with a price promotion than when it is not; and (c) if the valuation of a product is first elicited with WTP and then elicited with WTB, consumers always value the product less when it is offered with a price promotion than when it is not. A value‐inference account is proposed for the above findings, according to which, consumers infer the value of a promoted product differently when the valuation is elicited only with WTP or only with WTB. Theoretically, this research extends prior literature on sales promotion, showing that the valuation of a promotion is subject to the elicitation method. Practically, this research suggests how to help consumers manage their purchase intentions for promoted products.
Chemical Composition and Antioxidant Activity of Tuber indicum from Different Geographical Regions of China
Authors: Li Jia‐Mei , Liang Han‐Qiao , Qiao Peng , Su Kai‐Mei , Liu Pei‐Gui , Guo Shun‐Xing , Chen Juan
Published: January 2019

Tuber indicum, an endemic truffle species in eastern Asian, is an edible mushroom that is both an important export and widely distributed across China. Many existing studies on truffles focus on analyzing their taxonomy, population genetics, volatile organic compounds and artificial cultivation of the truffles, while little information is available about their nutrient composition and pharmacological activity, especially the relationship between chemical composition in ascocarps and their geographic distributions. This study presents a comprehensive investigation of the chemical composition of T. indicum, including free sugars, fatty acids, organic acids, phenolic acids, flavonoids, and polysaccharides, and tracks the antioxidant activity of T. indicum ascocarps collected from five geographical regions of four provinces in P. R. China: Hebei, Tibet, Yunnan, and Liaoning province. Our results showed that T. indicum collected from Qujing, Yunnan province, possessed the highest amount of free sugars (23.67 mg/g dw), total flavonoids (2.31 mg/g dw), total phenolics (4.46 mg/g dw) and the highest DPPH and ABTS radical‐scavenging activities. The amount of water‐soluble polysaccharides was the highest (115.24 mg/g dw) in ascocarps from Tibet, the total organic acids was the highest (22.073 mg/g dw) in ascocarps from Gongshan, and polyunsaturated fatty acids were most abundant in those from Hebei province. This study reveals that the quantity of chemical compounds in T. indicum varies by geographical origin. Detecting differences in chemical composition may provide important data for understanding the relationship between environmental factors and truffle formation, as well as quality evaluation of the commercial species T. indicum throughout China.
Bioinspired Design of Lysolytic Triterpenoid–Peptide Conjugates that Kill African Trypanosomes
Authors: Leeder W.‐Matthias , Giehler Fabian , Joswig Juliane , Göringer H. Ulrich
Published: January 2019

Humans have evolved a natural immunity against Trypanosoma brucei infections, which is executed by two serum (lipo)protein complexes known as trypanolytic factors (TLF). The active TLF ingredient is the primate‐specific apolipoprotein L1 (APOL1). The protein has a pore‐forming activity that kills parasites by lysosomal and mitochondrial membrane fenestration. Of the many trypanosome subspecies, only two are able to counteract the activity of APOL1; this illustrates its evolutionarily optimized design and trypanocidal potency. Herein, we ask whether a synthetic (syn) TLF can be synthesized by using the design principles of the natural TLF complexes but with different chemical building blocks. We demonstrate the stepwise development of triterpenoid–peptide conjugates, in which the triterpenoids act as a cell‐binding, uptake and lysosomal‐transport modules and the synthetic peptide GALA acts as a pH‐sensitive, pore‐forming lysolytic toxin. As designed, the conjugate kills infective‐stage African trypanosomes through lysosomal lysis thus demonstrating a proof‐of‐principle for the bioinspired, forward‐design of a synTLF.
Natural Voltage‐Gated Sodium Channel Ligands: Biosynthesis and Biology
Authors: Lukowski April L. , Narayan Alison R. H.
Published: January 2019

Natural product biosynthetic pathways are composed of enzymes that use powerful chemistry to assemble complex molecules. Small molecule neurotoxins are examples of natural products with intricate scaffolds which often have high affinities for their biological targets. The focus of this Minireview is small molecule neurotoxins targeting voltage‐gated sodium channels (VGSCs) and the state of knowledge on their associated biosynthetic pathways. There are three small molecule neurotoxin receptor sites on VGSCs associated with three different classes of molecules: guanidinium toxins, alkaloid toxins, and ladder polyethers. Each of these types of toxins have unique structural features which are assembled by biosynthetic enzymes and the extent of information known about these enzymes varies among each class. The biosynthetic enzymes involved in the formation of these toxins have the potential to become useful tools in the efficient synthesis of VGSC probes.
Probing Colocalization of N‐Ras and K‐Ras4B Lipoproteins in Model Biomembranes
Authors: Li Lei , Dwivedi Mridula , Patra Satyajit , Erwin Nelli , Möbitz Simone , Winter Roland
Published: January 2019

Signaling of N‐Ras and K‐Ras4B proteins depends strongly on their correct localization in the cell membrane. In vivo studies suggest that intermolecular interactions foster the self‐association of both N‐Ras and K‐Ras4B and the formation of nanoclusters in the cell membrane. As sites for effector binding, nanocluster formation is thought to be essential for effective signal transmission of both N‐Ras and K‐Ras4B. To shed more light on the spatial arrangement and mechanism underlying the proposed cross‐talk between spatially segregated Ras proteins, the simultaneous localization of N‐Ras and K‐Ras4B and their effect on the lateral organization of a heterogeneous model biomembrane has been studied by using AFM and FRET methodology. It is shown that, owing to the different natures of their membrane anchor systems, N‐Ras and K‐Ras4B not only avoid assembly in bulk solution and do not colocalize, but rather form individual nanoclusters that diffuse independently in the fluid membrane plane.
The Role of the Anode Material in Selective Penicillin G Oxidation in Urine
Authors: Cotillas Salvador , Lacasa Engracia , Herraiz Miguel , Sáez Cristina , Cañizares Pablo , Rodrigo Manuel A.
Published: January 2019

In this work, the removal of antibiotic penicillin G by electrolysis with boron doped diamond (BDD) and mixed metal oxide (MMO) anodes in urine media is evaluated. First, electrolysis in different water matrices (sulfate, chloride and urine) were carried out with diamond anodes to shed light on the contribution of mediated mechanisms. Results showed that penicillin G was completely removed by electrolysis for electric charges below 5 Ah dm−3, regardless of the water matrix and the current density applied (10‐100 mA cm−2). Then, the influence of the anode material was evaluated for the degradation of penicillin G in urine media. A complete removal of the antibiotic was attained, regardless of the tested anode material, although the BDD anode was found to be more efficient than MMO. Results also showed that, at the current charges in which the antibiotic is depleted, the removal of other organics was much lower and the formation of chlorates was negligible, especially operating at low current densities. Because of this selective oxidation of the pharmaceutical compound, electrolysis can be proposed to be used as a pre‐treatment technology for later and cheaper biological treatment.
Overview of Surrogate Modeling in Chemical Process Engineering
Authors: McBride Kevin , Sundmacher Kai
Published: January 2019

The ability to accurately model and simulate chemical processes has been paramount to the growing success and efficiency in process design and operation. These improvements usually come with increasing complexity of the underlying models leading to substantial computational effort in their use. It may also occur that the structure of the model is sometimes unknown making optimization and study difficult. To circumvent these issues, mathematically simpler models, commonly known as surrogate models, have been designed and used to successfully replace these complex, underlying models with much success. This technique has seen increasing use within the chemical process engineering field and this article summarizes some popular surrogates and their recent use in this area.
The Influence of the Amino Acid Side Chains on the Raman Optical Activity Spectra of Proteins
Authors: Mensch Carl , Johannessen Christian
Published: January 2019

The front cover artwork is provided by Dr. Carl Mensch and Prof. Christian Johannessen from the Molecular Spectroscopy group at the University of Antwerp and the Ghent Quantum Chemistry Group. The image shows the spectroscopic response to the conformational flexibility of protein side‐chains as probed by Raman optical activity. Read the full text of the Article at 10.1002/cphc.201800924.
Stock price prediction using k‐medoids clustering with indexing dynamic time warping
Authors: Nakagawa Kei , Imamura Mitsuyoshi , Yoshida Kenichi
Published: January 2019

Various methods to predict stock prices have been studied. In the field of empirical finance, feature values for prediction include “value” and “momentum”. In this research, we use the pattern of stock price fluctuations which has not been fully utilized in the financial market as the input feature of prediction. We extract the representative price fluctuation patterns with k‐Medoids Clustering with Indexing Dynamic Time Warping method. This method is k‐medoids clustering on dissimilarity matrix using IDTW which measures DTW distance between indexed time‐series. We can visualize and grasp a price fluctuation pattern effective for prediction with the proposed method. To demonstrate the advantages of the proposed method, we analyze its performance using TOPIX. Experimental results show that the proposed method is effective for predicting monthly stock price changes.
Effect of the Chirality of Counter Anions on the Vapochromic Behavior of Luminescent PtII Complexes
Authors: Shigeta Yasuhiro , Kobayashi Atsushi , Yoshida Masaki , Kato Masako
Published: January 2019

New luminescent PtII complexes with the chiral counter anions [PtCl(tpy)](l‐Hta) (1‐L) and [PtCl(tpy)](dl‐Hta) (1‐DL; tpy = 2,2′:6′,2′′‐terpyridine; l‐H2ta = l‐tartaric acid; dl‐H2ta = racemic tartaric acid) were synthesized and their vapochromic behavior was evaluated. Single crystal X‐ray analysis revealed that the stacked square‐planar PtII molecules in anhydrous 1‐DL formed a one‐dimensional columnar structure with weak intermolecular Pt···Pt interactions, while in anhydrous 1‐L the PtII molecules were dimerized with Pt···Pt interactions to form a zig‐zag stacked column. These differences were attributed to the different hydrogen bonding in the dl‐ and l‐Hta– ions. The dihydrates of 1‐DL and 1‐L displayed near‐identical crystal structures with comparable emission spectra derived from 3π–π* ligand emission. Both dihydrates exhibited MeOH‐vapor‐induced dehydration to form the anhydrous complexes. These presented broad 3MMLCT emission (549 and 565 nm, respectively), affected by the degree of intermolecular Pt···Pt interactions.