bluuebunny/crossref_metadata_2025 huggingface dataset:
Multipoint Nanolaser Array in an Individual Core–Shell CdS Branched Nanostructure
Authors: Hao Yan , Ding Chunjie , Lu Tianqi , Xie Lingling , Nan Pengfei , Guo Shuai , Wang Xianshuang , Li Angze , Xu Xiangjun , Zou Bingsuo , Liu Ruibin
Published: March 2020

Nanoscale laser arrays are attractive for their potential applications in highly integrated nanodevices, which are always obtained by nanowire arrays with complicated fabrication techniques. Here, a quite different nanolaser array is successfully realized based on a highly ordered core–shell CdS branched nanostructure with implanted Sn nanoparticles in junctions that split the individual multichannel nanostructures to various microcavities with effective light confinement and oscillation, thus to achieve a multipoint nanolaser array. Under the excitation of an ultraviolet laser, the strong band‐edge emission can be well reflected between Sn nanoparticles at junctions and effectively scattered into branch segments due to Sn nanoparticles existence in junctions, furthermore oscillating in various microcavities along trunks or branches to form multipoint lasing from Fabry‐Pérot (F‐P) mode with a quality factor up to 990 and the low threshold at around 3.78 MW cm−2. The corresponding fluorescent microscope images further demonstrate the formation of multipoint F‐P lasing at various segments. The theoretical simulation indicates that implanted Sn nanoparticles work as hot point to enhance the confinement of light around the Sn centers. The existence of surface plasmon from the Sn metal particles is further confirmed by the polarization dependent photoluminescence measurement. The results provide a new way to realize nanolaser arrays.
Single White‐Emitting Polymers with High Efficiency, Low Roll‐Off, and Enhanced Device Stability by Using Through‐Space Charge Transfer Polymer with Blue Delayed Fluorescence as Host for Yellow Phosphor
Authors: Hu Jun , Li Qiang , Shao Shiyang , Wang Lixiang , Jing Xiabin , Wang Fosong
Published: March 2020

White‐emitting polymers hold great promise for the production of low‐cost and large‐area light sources via solution process. However, the development of efficient and stable white‐emitting polymers has been a formidable challenge yet. Here a strategy for single white‐emitting polymers is demonstrated with high efficiency, low roll‐off, and enhanced device stability by using through‐space charge transfer (TSCT) polymer with small singlet‐triplet energy splitting and blue thermally activated delayed fluorescence as host for yellow phosphor. This strategy not only combines delayed fluorescence and phosphorescence in one polymer to make full use of excitons but also enables the long‐range Förster resonant energy transfer from polymer host to phosphor for suppressing triplet quenching at high luminance, leading to state‐of‐the‐art luminous efficiency of 50.9 cd A−1 at 1000 cd m−2 (corresponding to a low roll‐off of 1.9%) for white‐emitting polymers, together with a tenfold increase in device lifetime over the control polymers based on a conventional polymer host. These results shed light on the prospect of using TSCT polymer with delayed fluorescence as host for developing efficient and stable white‐emitting polymers for solution‐processed white organic light‐emitting diodes.
Rhodium(III)‐Catalyzed Oxidative C(sp3)−H Alkenylation of 8‐Methylquinolines with Maleimides Under Aerobic Conditions
Authors: Shan Baode , Kang Baotao , Song Mingyue , Wang Rui , Chen Guozhu , Li Cuncheng , Zhao Huaiqing
Published: March 2020

A rhodium(III)‐catalyzed C(sp3)−H alkenylation of 8‐methylquinolines with electron‐deficient maleimides has been accomplished with the combination of copper acetate, 2,2,6,6‐tetramethylpiperidine‐1‐oxyl and oxygen as the oxidant. A variety of maleimides react with various 8‐methylquinolines to furnish the corresponding alkenylated products in moderate to good yields.

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The invasive plant Solidago canadensis exhibits partial local adaptation to low salinity at germination but not at later life‐history stages
Authors: Jin Huifei , Yuan Yongge , Gao Fanglei , Oduor Ayub M.O. , Li Junmin
Published: March 2020

Premise

Evolutionary adaptation may enable plants to inhabit a broad range of environments. However, germination and early life‐history stages have seldom been considered in estimates of evolutionary adaptation. Moreover, whether soil microbial communities can influence evolutionary adaptation in plants remains little explored.

Methods

We used reciprocal transplant experiments to investigate whether two populations of an invasive plant Solidago canadensis that occur in contrasting habitats of low versus high salinity expressed adaptation to the respective salinity levels. We germinated S. canadensis seeds collected from low‐and high‐salinity habitats under low‐ and high‐salt treatments. We also raised S. canadensis seedlings from the two salinity habitats under low‐ and high‐salt treatments and in the presence versus absence of microbial communities from the two habitats.

Results

Genotypes from a low‐salinity habitat had higher germination rates under low‐salt treatment than genotypes from a high‐salinity habitat. However, both genotypes had similar germination rates under a high‐salt treatment. The two genotypes also had similar seedling survival and biomass responses to low‐ and high‐salt treatments. Nevertheless, seedling biomass was significantly higher under low salt treatment. Soil microbial communities did not influence biomass of S. canadensis under the two salt treatments.

Conclusions

The results on germination rates suggest partial local adaptation to low salinity. However, there was no evidence of local adaptation to salinity at the seedling survival and growth stages. The finding that germination and seedling biomass responded to different salt treatments suggests that the two traits are important for salt tolerance.
Playback point counts and N‐mixture models suggest higher than expected abundance of the critically endangered blond titi monkey in northeastern Brazil
Authors: Coelho Igor P. , Collins Sara J. , Santos Júnior Eduardo M. , Valença‐Montenegro Mônica M. , Jerusalinsky Leandro , Alonso André C.
Published: March 2020

Effective management of threatened species requires accurate population size estimation and monitoring. However, reliable population size estimates are lacking for many endangered species. The critically endangered blond titi monkey (Callicebus barbarabrownae) is an endemic primate of the Caatinga biome in Northeastern Brazil. A previous assessment based on presence‐only data estimated a minimum population size of 260 mature individuals in 2,636 km2, and studies based on visual records suggested very low local relative abundance. However, this cryptic species is known to be difficult to visually detect. We played back recordings of C. barbarabrownae loud calls to count the number of responding groups in 34 sampling sites during 9 consecutive days in a 221‐km2 study area. Repeated group counts at sites were used in N‐mixture models, which account for imperfect detection, to estimate the number of groups in relation to dry forest area and distance to villages. We estimated a total of 91 groups in the study area. Considering the mean number of adults per group as three, we estimated a population of 273 adult individuals, resulting in a density of 2.3 individuals/km2 in the dry forest habitat. Detection probability was four times higher for surveys conducted between sunrise to midmorning than between midmorning to sunset. We also found that C. barbarabrownae abundance increases with increasing dry forest area and increasing distance to the nearest village, indicating the need to promote dry forest restoration in the Caatinga. As our results suggest a larger population of C. barbarabrownae than had been previously estimated for its entire distribution, our results suggest a need for similar assessments in other areas to reliably estimate the total population size. This study demonstrates how playback surveys coupled with N‐mixture models can be used to estimate population sizes of acoustically‐responsive primates, and thus contribute to more effective conservation management.
Schein's Remand Decision Goes Back To the Supreme Court. What's Next?
Authors: Loree Philip J.
Published: March 2020

In what has become protracted—but necessary—Federal Arbitration Act litigation, Henry Schein Inc., a Melville, N.Y.‐based dental equipment distributor (the “petitioner”) seeking to arbitrate disputes pursuant to a written agreement has for the second time petitioned the U.S. Supreme Court for review.
Tribunals, Providers, and Courts Must Help Protect Reasoned Awards
Authors: McArthur John Burritt
Published: March 2020

The first two articles in this Alternatives series addressed first and foremost the parties, and, indirectly, their counsel. See “Parties, Beware: Current Practices and Judicial Standards Threaten Your Right to Truly Reasoned Awards,” 38 Alternatives 19 (February 2020) (available at http://bit.ly/2uacjmq), and “Parties Usually Benefit Most from Reasoned Awards, Not Standard Awards,” 38 Alternatives 44 (March 2020) (available at http://bit.ly/2Iv6xPQ).
Age‐related rhesus macaque models of COVID‐19
Authors: Yu Pin , Qi Feifei , Xu Yanfeng , Li Fengdi , Liu Peipei , Liu Jiayi , Bao Linlin , Deng Wei , Gao Hong , Xiang Zhiguang , Xiao Chong , Lv Qi , Gong Shuran , Liu Jiangning , Song Zhiqi , Qu Yajin , Xue Jing , Wei Qiang , Liu Mingya , Wang Guanpeng , Wang Shunyi , Yu Haisheng , Liu Xing , Huang Baoying , Wang Wenling , Zhao Li , Wang Huijuan , Ye Fei , Zhou Weimin , Zhen Wei , Han Jun , Wu Guizhen , Jin Qi , Wang Jianwei , Tan Wenjie , Qin Chuan
Published: March 2020

Background

Since December 2019, an outbreak of the Corona Virus disease 2019 (COVID‐19) caused by severe acute respiratory syndrome coronavirus (SARS‐CoV‐2) in Wuhan, China, has become a public health emergency of international concern. The high fatality of aged cases caused by SARS‐CoV‐2 was a need to explore the possible age‐related phenomena with non‐human primate models.

Methods

Three 3‐5 years old and two 15 years old rhesus macaques were intratracheally infected with SARS‐CoV‐2, and then analyzed by clinical signs, viral replication, chest X‐ray, histopathological changes and immune response.

Results

Viral replication of nasopharyngeal swabs, anal swabs and lung in old monkeys was more active than that in young monkeys for 14 days after SARS‐CoV‐2 challenge. Monkeys developed typical interstitial pneumonia characterized by thickened alveolar septum accompanied with inflammation and edema, notably, old monkeys exhibited diffuse severe interstitial pneumonia. Viral antigens were detected mainly in alveolar epithelial cells and macrophages.

Conclusion

SARS‐CoV‐2 caused more severe interstitial pneumonia in old monkeys than that in young monkeys. Rhesus macaque models infected with SARS‐CoV‐2 provided insight into the pathogenic mechanism and facilitated the development of vaccines and therapeutics against SARS‐CoV‐2 infection.
Secondary Amino Alcohols: Traceless Cleavable Linkers for Use in Affinity Capture and Release
Authors: Pomplun Sebastian , Shugrue Christopher R. , Schmitt Adeline M. , Schissel Carly K. , Farquhar Charlotte E. , Pentelute Bradley L.
Published: March 2020

Capture and release of peptides is often a critical operation in the pathway to discovering materials with novel functions. However, the best methods for efficient capture impede facile release. To overcome this challenge, we report linkers based on secondary amino alcohols for the release of peptides after capture. These amino alcohols are based on serine (seramox) or isoserine (isoseramox) and can be incorporated into peptides during solid‐phase peptide synthesis through reductive amination. Both linkers are quantitatively cleaved within minutes under NaIO4 treatment. Cleavage of isoseramox produced a native peptide N‐terminus. This linker also showed broad substrate compatibility; incorporation into a synthetic peptide library resulted in the identification of all sequences by nanoLC‐MS/MS. The linkers are cell compatible; a cell‐penetrating peptide that contained this linker was efficiently captured and identified after uptake into cells. These findings suggest that such secondary amino alcohol based linkers might be suitable tools for peptide‐discovery platforms.
Distance Synergy of MoS2‐Confined Rhodium Atoms for Highly Efficient Hydrogen Evolution
Authors: Meng Xiangyu , Ma Chao , Jiang Luozhen , Si Rui , Meng Xianguang , Tu Yunchuan , Yu Liang , Bao Xinhe , Deng Dehui
Published: March 2020

Perturbing the electronic structure of the MoS2 basal plane by confining heteroatoms offers the opportunity to trigger in‐plane activity for the hydrogen evolution reaction (HER). The key challenge consists of inducing the optimum HER activity by controlling the type and distribution of confined atoms. A distance synergy of MoS2‐confined single‐atom rhodium is presented, leading to an ultra‐high HER activity at the in‐plane S sites adjacent to the rhodium. By optimizing the distance between the confined Rh atoms, an ultra‐low overpotential of 67 mV is achieved at a current density of 10 mA cm−2 in acidic solution. Experiments and first‐principles calculations demonstrate a unique distance synergy between the confined rhodium atoms in tuning the reactivity of neighboring in‐plane S atoms, which presents a volcanic trend with the inter‐rhodium distance. This study provides a new strategy to tailor the activity of MoS2 surface via modulating the distance between confined single atoms.
Organobor‐Funktionalisierung ermöglicht die hierarchische Aggregation gigantischer Polyoxometallat‐Nanokapseln
Authors: Li Shujun , Zhou Yanfang , Ma Nana , Zhang Jie , Zheng Zhiping , Streb Carsten , Chen Xuenian
Published: March 2020

Die Aggregation molekularer Metalloxide in größere Superstrukturen kann die Lücke zwischen molekularen Verbindungen und Festkörperstrukturen überbrücken. Hier berichten wir über die Funktionalisierung von Polyoxowolframaten mit Organobor‐Substituenten, was zur Bildung gigantischer Polyoxometallat‐Nanokapseln mit Dimensionen von bis zu vier Nanometern führt. Ein Schlüssel‐Schloss‐Mechanismus erlaubt das regiospezifische Verankern aromatischer Boronsäuren an Metall‐funktionalisierten Dawson‐Anionen [M3P2W15O62]9− (M=TaV oder NbV). Dies führt zu neuartigen Nanokapseln bestehend aus bis zu 12 POM‐Enheiten. Experimentelle und theoretische Studien geben erste Einblicke in die Funktion der Organobor‐Einheiten sowie der metallfunktionalisierten POMs für die Aggregation der Kapseln. Die Studie legt den Grundstein für die Entwicklung organo‐POM‐basierter funktioneller Nanostrukturen.
Enhanced CO2 Electroreduction on Neighboring Zn/Co Monomers by Electronic Effect
Authors: Zhu Wenjin , Zhang Lei , Liu Sihang , Li Ang , Yuan Xintong , Hu Congling , Zhang Gong , Deng Wanyu , Zang Ketao , Luo Jun , Zhu Yuanmin , Gu Meng , Zhao Zhi‐Jian , Gong Jinlong
Published: March 2020

It is of great significance to reveal the detailed mechanism of neighboring effects between monomers, as they could not only affect the intermediate bonding but also change the reaction pathway. This paper describes the electronic effect between neighboring Zn/Co monomers effectively promoting CO2 electroreduction to CO. Zn and Co atoms coordinated on N doped carbon (ZnCoNC) show a CO faradaic efficiency of 93.2 % at −0.5 V versus RHE during a 30‐hours test. Extended X‐ray absorption fine structure measurements (EXAFS) indicated no direct metal–metal bonding and X‐ray absorption near‐edge structure (XANES) showed the electronic effect between Zn/Co monomers. In situ attenuated total reflection‐infrared spectroscopy (ATR‐IR) and density functional theory (DFT) calculations further revealed that the electronic effect between Zn/Co enhanced the *COOH intermediate bonding on Zn sites and thus promoted CO production. This work could act as a promising way to reveal the mechanism of neighboring monomers and to influence catalysis.
Efficient Hydrogen Oxidation Catalyzed by Strain‐Engineered Nickel Nanoparticles
Authors: Ni Weiyan , Wang Teng , Schouwink Pascal Alexander , Chuang Yu‐Chun , Chen Hao Ming , Hu Xile
Published: March 2020

The hydroxide‐exchange membrane fuel cell (HEMFC) is a promising energy conversion device. However, the development of HEMFC is hampered by the lack of platinum‐group‐metal‐free (PGM‐free) electrocatalysts for the hydrogen oxidation reaction (HOR). Now, a Ni catalyst is reported that exhibits the highest mass activity in HOR for a PGM‐free catalyst as well as excellent activity in the hydrogen evolution reaction (HER). This catalyst, Ni‐H2‐2 %, was optimized through pyrolysis of a Ni‐containing metal‐organic framework precursor under a mixed N2/H2 atmosphere, which yielded carbon‐supported Ni nanoparticles with different levels of strains. The Ni‐H2‐2 % catalyst has an optimal level of strain, which leads to an optimal hydrogen binding energy and a high number of active sites.
Label‐Free Nanoimaging of Neuromelanin in the Brain by Soft X‐ray Spectromicroscopy
Authors: Brooks Jake , Everett James , Lermyte Frederik , Tjhin Vindy Tjendana , Banerjee Samya , O'Connor Peter B. , Morris Christopher M. , Sadler Peter J. , Telling Neil D. , Collingwood Joanna F.
Published: March 2020

A hallmark of Parkinson's disease is the death of neuromelanin‐pigmented neurons, but the role of neuromelanin is unclear. The in situ characterization of neuromelanin remains dependent on detectable pigmentation, rather than direct quantification of neuromelanin. We show that direct, label‐free nanoscale visualization of neuromelanin and associated metal ions in human brain tissue can be achieved using synchrotron scanning transmission x‐ray microscopy (STXM), through a characteristic feature in the neuromelanin x‐ray absorption spectrum at 287.4 eV that is also present in iron‐free and iron‐laden synthetic neuromelanin. This is confirmed in consecutive brain sections by correlating STXM neuromelanin imaging with silver nitrate‐stained neuromelanin. Analysis suggests that the 1s–σ* (C−S) transition in benzothiazine groups accounts for this feature. This method illustrates the wider potential of STXM as a label‐free spectromicroscopy technique applicable to both organic and inorganic materials.
Catalytic Hydroetherification of Unactivated Alkenes Enabled by Proton‐Coupled Electron Transfer
Authors: Tsui Elaine , Metrano Anthony J. , Tsuchiya Yuto , Knowles Robert R.
Published: March 2020

We report a catalytic, light‐driven method for the intramolecular hydroetherification of unactivated alkenols to furnish cyclic ether products. These reactions occur under visible‐light irradiation in the presence of an IrIII‐based photoredox catalyst, a Brønsted base catalyst, and a hydrogen‐atom transfer (HAT) co‐catalyst. Reactive alkoxy radicals are proposed as key intermediates, generated by direct homolytic activation of alcohol O−H bonds through a proton‐coupled electron‐transfer mechanism. This method exhibits a broad substrate scope and high functional‐group tolerance, and it accommodates a diverse range of alkene substitution patterns. Results demonstrating the extension of this catalytic system to carboetherification reactions are also presented.
Good extrusion foaming performance of long‐chain branched PET induced by its enhanced crystallization property
Authors: Yao Shun , Guo Tianhao , Liu Tao , Xi Zhenhao , Xu Zhimei , Zhao Ling
Published: March 2020

Poly(ethylene terephthalate) (PET) was modified by regulating different contents of branching agent epoxy‐based multifunctional oligomer and chain extender pyromellitic dianhydride in reactive extrusion process. The modified PET with better long‐chain branched (LCB) structure boosted its rheological properties, and its enhancement of melt viscoelasticity resulted in excellent foamability in molten‐state foaming process using supercritical CO2 as blowing agent. More importantly, the branched structures acted as crystal sites to accelerate the crystallization kinetic of LCB PET whether under atmospheric pressure or high‐pressure CO2. The shear and elongation flow inside die further quickly induced the crystallization of LCB PET. The rapidly generated fine crystals could both introduce heterogeneous cell nucleation and suppress CO2 escape, so the cell morphology of LCB PET in continuous extrusion foaming process exhibited a three‐fold increase in cell density and smaller uniform cell size with respect to those of other foam‐grade PET with long‐chain structure.
Optimized Fluorescent Probe for Specific Imaging of Glutathione S‐Transferases in Living Cells and Mice
Authors: Song Aiguo , Shen Xin , Feng Tian , Gai Shouchang , Wei Haiqing , Li Xinxin , Chen Hui
Published: March 2020

GSTP1 has been considered to be a marker for malignancy in many tissues. However, the existing GST fluorescent probes are unfavorable for in vivo imaging because of the limited emission wavelength or insufficient fluorescence enhancement (six‐fold). The limited fluorescence enhancement of GST fluorescent probes is mainly ascribed to the high background signals resulting from the spontaneous reaction between GSH and the probes. In this work, a highly specific GST probe with NIR emission has been successfully developed through optimization of the essential unit of the probe to repress the spontaneous reaction. The novel GST probe exhibits over 100‐fold fluorescence enhancement upon incubation with GSTP1/GSH and high selectivity over other potential interference. In addition, the probe has been proved to be capable of tracking endogenous GST in A549 cells. Finally, the in vivo imaging results demonstrate that the probe can be used for effective imaging of endogenous GST activity in subcutaneous tumor mouse with high contrast.
Self‐Supported FeP‐CoMoP Hierarchical Nanostructures for Efficient Hydrogen Evolution
Authors: Wang Qin , Wang Zhiying , Zhao Yue , Li Fumin , Xu Ling , Wang Xiaoming , Jiao Huan , Chen Yu
Published: March 2020

Fabricating highly efficient electrocatalysts for electrochemical hydrogen generation is a top priority to relief the global energy crisis and environmental contamination. Herein, a rational synthetic strategy is developed for constructing well‐defined FeP−CoMoP hierarchical nanostructures (HNSs). In general terms, the self‐supported Co nanorods (NRs) are grown on conductive carbon cloth and directly serve as a self‐sacrificing template. After solvothermal treatment, Co NRs are converted into well‐ordered Co−Mo nanotubes (NTs). Subsequently, the small‐sized Fe oxyhydroxide nanorods arrays are hydrothermally grown on the surface of Co−Mo NTs to form Fe−Co−Mo HNSs, which are then converted into FeP−CoMoP HNSs through a facile phosphorization treatment. FeP−CoMoP HNSs display high activity for hydrogen evolution reaction (HER) with an ultralow cathodic overpotential of 33 mV at 10 mA cm−2 and a Tafel slope of 51 mV dec−1. Moreover, FeP−CoMoP HNSs also possess an excellent electrochemical durability in alkaline media. First‐principles density functional theory (DFT) calculations demonstrate that the remarkable HER activitiy of FeP−CoMoP HNSs originates from the synergistic effect between FeP and CoMoP.
Bimetal‐organic Framework‐derived Co9S8/ZnS@NC Heterostructures for Superior Lithium‐ion Storage
Authors: Duan Junfei , Wang Yongkang , Li Hongxing , Wei Donghai , Wen Fang , Zhang Guanhua , Liu Piao , Li Lingjun , Zhang Wei‐bing , Chen Zhaoyong
Published: March 2020

Heterostructure engineering of electrode materials, which is expected to accelerate the ion/electron transport rates driven by a built‐in internal electric field at the heterointerface, offers unprecedented promise in improving their cycling stability and rate performance. Herein, carbon nanotubes with Co9S8/ZnS heterostructures embedded in a N‐doped carbon framework (Co9S8/ZnS@NC) have been rationally designed via an in‐situ vapor chemical transformation strategy with the aid of thiophene, which not only acted as carbon source for the growth of carbon nanotubes but also as sulfur source for the sulfurization of metal Zn and Co. Density functional theory (DFT) calculation shows an about 3.24 eV electrostatic potential difference between ZnS and Co9S8, which results in a strong electrostatic field across the interface that makes electrons transfer from Co9S8 to the ZnS side. As expected, a stable cycling performance with reversible capacity of 411.2 mAh g−1 at 1000 mA g−1 after 300 cycles, excellent rate capability (324 mAh g−1 at 2000 A g−1) and a high percentage of pseudocapacitance contribution (87.5% at 2.2 mv/s) for lithium‐ion batteries (LIBs) are achieved. This work provides a possible strategy for designing multicomponent heterostructural materials for application in energy storage and conversion fields.
Combining particle tracking microrheology and viscometry for the study of DNA aqueous solutions
Authors: Stefanopoulou Evdokia , Papagiannopoulos Aristeidis
Published: March 2020

We use video particle tracking microrheology (VPTMR) in order to investigate the viscoelasticity of salmon DNA and correlate it to its steady‐flow shear‐thinning viscosity. Aqueous solutions of DNA are tested in a wide concentration range from the dilute to the semidilute unentangled concentration regime. The observed mean squared displacement shows power‐law scaling with lag‐time which is equivalent to power‐law behavior of the complex modulus as a function of frequency that is, |G*(ω)| = S ∙ ω
α. The relaxation exponent
α changes abruptly with concentration in the semidilute regime from about 1 to about 0.5 which is the exponent predicted by the Rouse model. The quasi‐property
S follows the scaling of viscosity for uncharged polymers near θ‐conditions in the semidilute regime that is, with
νeff = 0.50 − 0.51. The shear‐thinning exponent observed by viscometry increases gradually towards the value of 0.5 which has been predicted for Rouse chains under flow. Our findings are in agreement with recent studies of DNA solutions where DNA is treated as a model polymer and addresses the low‐molar mass regime of DNA viscoelasticity. This work demonstrates that the combination of passive particle tracking with viscometry can provide a complete picture on the viscoelasticity of DNA‐based biopolymer materials.
High‐level production of 3‐hydroxypropionic acid from glycerol as a sole carbon source using metabolically engineered Escherichia coli
Authors: Kim Je Woong , Ko Yoo‐Sung , Chae Tong Un , Lee Sang Yup
Published: March 2020

As climate change is an important environmental issue, the conventional petrochemical‐based processes to produce valuable chemicals are being shifted toward eco‐friendly biological‐based processes. In this study, 3‐hydroxypropionic acid (3‐HP), an industrially important three carbon (C3) chemical, was overproduced by metabolically engineered Escherichia coli using glycerol as a sole carbon source. As the first step to construct a glycerol‐dependent 3‐HP biosynthetic pathway, the dhaB1234 and gdrAB genes from Klebsiella pneumoniae encoding glycerol dehydratase and glycerol reactivase, respectively, were introduced into E. coli to convert glycerol into 3‐hydroxypropionaldehyde (3‐HPA). In addition, the ydcW gene from K. pneumoniae encoding γ‐aminobutyraldehyde dehydrogenase, among five aldehyde dehydrogenases examined, was selected to further convert 3‐HPA to 3‐HP. Increasing the expression level of the ydcW gene enhanced 3‐HP production titer and reduced 1,3‐propanediol production. To enhance 3‐HP production, fed‐batch fermentation conditions were optimized by controlling dissolved oxygen (DO) level and employing different feeding strategies including intermittent feeding, pH‐stat feeding, and continuous feeding strategies. Fed‐batch culture of the final engineered E. coli strain with DO control and continuous feeding strategy produced 76.2 g/L of 3‐HP with the yield and productivity of 0.457 g/g glycerol and 1.89 g·L−1·h−1, respectively. To the best of our knowledge, this is the highest 3‐HP productivity achieved by any microorganism reported to date.
The role of intellectual and financial capital in competitiveness and performance: A study of emerging small and medium enterprises
Authors: Khattak Muhammad S. , Shah Syed Z. A.
Published: March 2020

The present research scrutinizes the influence of intellectual capital and financial capital (FC) on the small and medium enterprises' (SMEs) performance with a competitive advantage (CA) as a mediator. A plethora of research has been carried out to test the relationships among intellectual capital (IC), FC, and firm performance (FP) across the globe. However, studies on the CA as a mediator among these variables are rare in SMEs. Moreover, none of the studies of this landscape could be traced in developing countries particularly in Pakistan. This research examines the mediating role of CA between IC and FP as well as between FC and FP. A self‐administered survey was used to gather information from 178 registered ventures located in Rawalpindi and Islamabad Regions. The findings of this study display that IC and FC have a significant positive impact on the performance of SMEs, also significant and positive association exists between CA and FP. The path between IC and SMEs performance as well as between FC and SMEs performance is significantly mediated by the CA. The results recommend that SMEs should give attention to both IC and FC to sustain their position in the competitive markets.
The Selectivity of Fosfosal for STAT5b over STAT5a is Mediated by Arg566 in the Linker Domain
Authors: Gräb Julian , Berg Thorsten
Published: March 2020

Fosfosal is the O‐phosphorylated derivative of salicylic acid, with documented clinical use as a prodrug for the treatment of inflammatory diseases. We recently discovered that fosfosal itself inhibits the protein‐protein interaction domain, the SH2 domain, of the tumor‐related transcription factor STAT5b. Here, we demonstrate that fosfosal is selective for STAT5b over its close homologue STAT5a. This selectivity is mediated by the STAT5b residue Arg566, located in the SH2 domain‐adjacent linker domain. Our data provide further evidence for the role of the STAT linker domain in determining the activity of small molecules against the SH2 domain. We present a refined binding model for fosfosal and STAT5b, which can serve as the basis for the development of fosfosal‐based STAT5b inhibitors.
Optochemical Control of Protein Degradation
Authors: Wu Peng , Manna Debasish
Published: March 2020

Optochemical approach has been successfully utilized to regulate cellular protein degradation with a high resolution of spatiotemporal control. In this highlight, we discuss two recent developments of combining reversible optochemical functionalities with the bifunctional proteolysis targeting chimeras, or PROTACs to achieve light‐controlled degradation of protein targets of interest. PHOTACs are azobeneze‐containing molecules that are inactive as trans forms and active as cis forms, switchable upon pulse‐irradiation with either an activating 390 nm light or a deactivating 525 nm light. In contrast, photoPROTACs are o‐F4‐azobenzene‐containing molecules that can be switched between active trans isomers and inactive cis isomers by a single irradiation event using 415 or 530 nm light. Combining these two optochemically controlled PROTAC systems has the potential to achieve orthogonal control on protein degradation.
Fluorophore‐Labeled Cyclic Nucleotides as Potent Agonists of Cyclic Nucleotide‐Regulated Ion Channels
Authors: Lelle Marco , Otte Maik , Bonus Michele , Gohlke Holger , Benndorf Klaus
Published: March 2020

High‐affinity fluorescent derivatives of cyclic adenosine and guanosine monophosphate are powerful tools for investigating their natural targets. Cyclic nucleotide‐regulated ion channels belong to these targets and are vital for many signal transduction processes, such as vision and olfaction. The relation of ligand binding to activation gating is still challenging, and there is a need for fluorescent probes that enable the process to be broken down to the single‐molecule level. This inspired us to prepare fluorophore‐labeled cyclic nucleotides, which are composed of a bright dye and a nucleotide derivative with a thiophenol motif at position 8 that has already been shown to enable superior binding affinity. These bioconjugates were prepared by a novel cross‐linking strategy that involves substitution of the nucleobase with a modified thiophenolate in good yield. Both fluorescent nucleotides are potent activators of different cyclic nucleotide‐regulated ion channels with respect to the natural ligand and previously reported substances. Molecular docking of the probes excluding the fluorophore reveals that the high potency can be attributed to additional hydrophobic and cation‐π interactions between the ligand and the protein. Moreover, the introduced substances have the potential to investigate related target proteins, such as cAMP‐ and cGMP‐dependent protein kinases, exchange proteins directly activated by cAMP or phosphodiesterases.
Autoimmune hemolytic anemia in a patient with chronic lymphocytic leukemia
Authors: Al Hadidi Samer , Udden Mark
Published: March 2020

Peripheral blood smear for patients with CLL and AIHA usually shows lymphoid cells with scant cytoplasm and small round nuclei with condensed chromatin, smudge cells and spherocytes.
Evaluation of Transport Phenomena for Removing Vanadium from Petrochemical Industry Solid Waste
Authors: Deniz Amanda Broska da Cruz , Valt Renata Bachmann Guimarães , Ponte Maria José Jerônimo de Santana , Ponte Haroldo de Araújo
Published: March 2020

Transport phenomena are investigated which are involved in the electrokinetic remediation process used for removing vanadium from deactivated catalysts from oil catalytic cracking that are currently allotted to cement plants and class‐I landfills. Variables such as the concentration of electrolyte, electric potential, and applied electric current were evaluated in order to determine the effects produced by electroosmosis, diffusion, hydraulic gradient, and electromigration on the removal of vanadium from the catalyst. It was observed that migration is the most relevant phenomenon in the remediation tests, and for the best remediation condition, the migratory flow accounted for about 87 % of the vanadium removal.
Guest‐Dependent Pressure‐Induced Spin Crossover in FeII4[MIV(CN)8]2 (M=Mo, W) Cluster‐Based Material Showing Persistent Solvent‐Driven Structural Transformations
Authors: Jankowski Robert , Reczyński Mateusz , Chorazy Szymon , Zychowicz Mikołaj , Arczyński Mirosław , Kozieł Marcin , Ogorzały Karolina , Makowski Wacław , Pinkowicz Dawid , Sieklucka Barbara
Published: March 2020

Discrete molecular species that can perform certain functions in response to multiple external stimuli constitute a special class of multifunctional molecular materials called smart molecules. Herein, cyanido‐bridged coordination clusters {[FeII(2‐pyrpy)2]4[MIV(CN)8]2}⋅4 MeOH⋅6 H2O (M=Mo (1 solv), M=W (2 solv) and 2‐pyrpy=2‐(1‐pyrazolyl)pyridine are presented, which show persistent solvent driven single‐crystal‐to‐single‐crystal transformations upon sorption/desorption of water and methanol molecules. Three full desolvation–resolvation cycles with the concomitant change of the host molecules do not damage the single crystals. More importantly, the Fe4M2 molecules constitute a unique example where the presence of the guests directly affects the pressure‐induced thermal spin crossover (SCO) phenomenon occurring at the FeII centres. The hydrated phases show a partial SCO with approximately two out‐of‐four FeII centres undergoing a gradual thermal SCO at 1 GPa, while in the anhydrous form the pressure‐induced SCO effect is almost quenched with only 15 % of the FeII centres undergoing high‐spin to low‐spin transition at 1 GPa.
Amorphous/Crystalline Hetero‐Phase TiO2‐Coated α‐Fe2O3 Core–Shell Nanospindles: A High‐Performance Artificial Nitrogen Fixation Electrocatalyst
Authors: Qiu Weibin , Luo Yu‐Xi , Liang Ru‐Ping , Qiu Jian‐Ding
Published: March 2020

Electrochemical nitrogen fixation techniques have emerged as a promisingly sustainable approach to face the challenge associated with nitrogen activation of ammonia synthesis by the Haber–Bosch process under ambient conditions. Herein, the performance of electrocatalytic nitrogen reduction for the production of α‐Fe2O3 nanospindles coated with mesoporous TiO2 with different crystallinity [denoted as α‐Fe2O3@mTiO2‐X (X=300, 400, and 500 °C)] were investigated. The as‐prepared α‐Fe2O3@mTiO2‐400 composite exhibits a large NH3 yield (27.2 μg h−1 mgcat.−1) at −0. 5 V vs. the reversible hydrogen electrode and a high Faradaic efficiency (13.3 %) in 0.1 m Na2SO4, with excellent electrochemical durability. This work presents a novel avenue for the rational design of efficient unique hetero‐phase nanocatalysts toward sustainable electrocatalytic N2 fixation.
Assessing Crystallisation Kinetics of Zr Metal–Organic Frameworks through Turbidity Measurements to Inform Rapid Microwave‐Assisted Synthesis
Authors: Griffin Sarah L. , Briuglia Maria L. , ter Horst Joop H. , Forgan Ross S.
Published: March 2020

Controlling the crystallisation of metal‐organic frameworks (MOFs), network solids of metal ions or clusters connected by organic ligands, is often hindered by the significant number of synthetic variables inherent to their synthesis. Coordination modulation, the addition of monotopic competing ligands to solvothermal syntheses, can allow tuning of physical properties (particle size, porosity, surface chemistry), enhance crystallinity, and select desired phases, by modifying the kinetics of self‐assembly, but its mechanism(s) are poorly understood. Herein, turbidity measurements were used to assess the effects of modulation on the solvothermal synthesis of the prototypical Zr terephthalate MOF UiO‐66 and the knowledge gained was applied to its rapid microwave synthesis. The studied experimental parameters—temperature, reagent concentration, reagent aging, metal precursor, water content, and modulator addition—all influence the time taken for onset of nucleation, and subsequently allow microwave synthesis of UiO‐66 in as little as one minute. The simple, low cost turbidity measurements align closely with previously reported in situ synchrotron X‐ray diffraction studies, proving their simplicity and utility for probing the nucleation of complex materials while offering significant insights to the synthetic chemist.
Multimeric Presentation of RGD Peptidomimetics Enhances Integrin Binding and Tumor Cell Uptake
Authors: Pina Arianna , Kadri Malika , Arosio Daniela , Dal Corso Alberto , Coll Jean‐Luc , Gennari Cesare , Boturyn Didier
Published: March 2020

The use of multimeric ligands is considered as a promising strategy to improve tumor targeting for diagnosis and therapy. Herein, tetrameric RGD (Arg‐Gly‐Asp) peptidomimetics were designed to target αvβ3 integrin‐expressing tumor cells. These compounds were prepared by an oxime chemoselective assembly of cyclo(DKP‐RGD) ligands and a cyclodecapeptide scaffold, which allows a tetrameric presentation. The resulting tetrameric RGD peptidomimetics were shown to improve αvβ3 integrin binding compared with the monomeric form. Interestingly, these compounds were also able to enhance tumor cell endocytosis in the same way as tetrameric RGD peptides. Altogether, the results show the potential of the tetrameric cyclo(DKP‐RGD) ligands for in vivo imaging and drug delivery.
Stereoselective Formation of Facial Tris‐Cyclometalated PtIV Complexes: Dual Phosphorescence from Heteroleptic Derivatives
Authors: López‐López Juan Carlos , Bautista Delia , González‐Herrero Pablo
Published: March 2020

A stereoselective synthetic route to homo‐ and heteroleptic facial tris‐cyclometalated PtIV complexes is reported, involving the oxidative addition of 2‐(2‐pyridyl)‐ or 2‐(1‐isoquinolinyl)benzenediazonium salts to cis‐[Pt(C^N)2] precursors, with C^N=cyclometalated 2‐(p‐tolyl)pyridine (tpy), 2‐phenylquinoline (pq), 2‐(2‐thienyl)pyridine or 1‐phenylisoquinoline (piq), to produce labile diazenide intermediates that undergo photochemical or thermal elimination of N2. The method allows the preparation of derivatives bearing cyclometalated ligands of low π–π* transition energies. The new complexes exhibit phosphorescence in fluid solution at room temperature arising from triplet ligand‐centered (3LC) excited states, which, in the cases of the heteroleptic derivatives, involve the ligand with the lowest π–π* gap. The heteroleptic piq derivatives exhibit fluorescence and dual phosphorescence from different ligand‐centered excited states in rigid media, demonstrating the potential of cyclometalated PtIV complexes as multi‐emissive materials.
Dicht‐ und Klebstoffe auf Silikonbasis
Authors: Wolf Andreas T.
Published: March 2020

Aufgrund ihrer außergewöhnlichen Eigenschaften und den daraus resultierenden, vielseitigen Anwendungsmöglichkeiten sind Dicht‐ und Klebstoffe auf Silikonbasis mittlerweile aus unserem Alltag nicht mehr wegzudenken. Dieser Teil der Artikelserie diskutiert die physikalischen und chemischen Verfestigungsmechanismen, die den anwendungsfertigen Dicht‐ oder Klebstoff in das funktionsfähige Fugenmaterial überführen. Bei den elastischen Dicht‐ und Klebstoffen stehen für die Verfestigung verschiedene chemische Vernetzungsmechanismen zur Verfügung, die zum Teil auch untereinander kombiniert werden können. Dabei kann jeder dieser Vernetzungsmechanismen – Polykondensation, Polyaddition und radikalische Kettenreaktion – durch verschiedene Vernetzertypen realisiert werden. Dieses breite Repertoire an chemischen Reaktionen ermöglicht es, maßgeschneiderte Produkte für eine Vielzahl von Marktsegmenten und Anwendungen zu entwickeln.
Response surface optimization of the photocatalytic degradation of atenolol using immobilized graphene‐TiO2 composite
Authors: Bhatia Vibhu , Manoli Kyriakos , Dhir Amit , Ray Ajay K.
Published: March 2020

Photocatalytic processes using semiconductors have been widely explored due to their fascinating benefits in environmental remediation. In this study, a four‐factor three‐level Box‐Benkhen design (BBD) was employed to assess the photocatalytic degradation of atenolol (ATL) using immobilized graphene‐TiO2 as a photocatalyst. The four variables that were considered in the BBD model were the photocatalyst concentration (10%‐20%), pH (4‐9), ATL concentration (10‐30 mg/L), and light intensity (60‐260 W/m2). A monolithic‐type swirl‐flow reactor, which allowed the immobilization of the photocatalyst, was employed in a semi‐batch system to study the photocatalytic degradation kinetics of ATL. The optimum conditions where the highest rate constant (0.667 min−1) was observed were graphene‐TiO2 concentration of 10%, pH of 6.5, ATL concentration of 30 mg/L, and light intensity of 160 W/m2. The developed model well predicted the observed values indicated by a high R2 of 0.897. Reaction rate constants obtained herein using graphene‐TiO2 in immobilized form were compared with slurry system and TiO2.
Modification of Hole Transport Layers for Fabricating High Performance Non‐fullerene Polymer Solar Cells
Authors: Babu B. Hari , Lyu Chengkun , Zhang Hongwei , Chen Zhihao , Li Fenghong , Feng Lin , Hao Xiao‐Tao
Published: March 2020

Summary of main observation and conclusion

Interfacial engineering is expected to be a feasible strategy to improve the charge transport properties of the hole transport layer (HTL), which is of crucial importance to boost the device performance of organic solar cells (OSCs). In this study, two types of alcohol soluble materials, 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ) and di‐tetrabutylammoniumcis–bis(isothiocyanato)bis (2,2’‐bipyridyl‐4,4’‐dicarboxylato) ruthenium(II) (N719) dye were selected as the dopant for HTL. The doping of F4‐TCNQ and N719 dye in poly (ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) with and without integrating a graphene quantum‐dots (G‐QDs) layer has been explored in poly[[2,6′‐4‐8‐di(5‐ethylhexylthienyl)benzo[1,2‐b:3,3‐b]dithiophene][3‐fluoro‐2[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thio‐phenediyl:(2,2′‐((2Z,2′Z)‐(((4,4,9, 9‐tetrakis(4‐hexylphenyl)‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,7‐diyl)bis(4‐((2‐ethylhexyl)oxy)thiophene‐5,2‐diyl))bis(methanylylidene))bis(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile (PTB7‐Th:IEICO‐4F) OSCs. The power conversion efficiency of the non‐fullerene OSCs has been increased to 10.12% from 8.84%. The influence of HTL modification on the nano‐morphological structures and photophysical properties is analyzed based on the comparative studies performed on the control and modified devices. The use of chemical doping and bilayer strategy optimizes the energy level alignment, nanomorphology, hole mobility, and work‐function of HTL, leading to considerable reduction of the leakage current and recombination losses. Our work demonstrates that the doping of HTL and the incorporation of G‐QDs layer to constitute a bilayer HTL is an promising strategy to fabricate high performance non‐fullerene polymer solar cells
Porous Nitrogen‐doped Reduced Graphene Oxide Gels as Efficient Supercapacitor Electrodes and Oxygen Reduction Reaction Electrocatalysts
Authors: Yang Liu , Wang Tao , Wu Dongling
Published: March 2020

Summary of main observation and conclusion

Heteroatom‐doped carbon materials have been widely used in energy storage and conversion such as supercapacitors and electrocatalysts. In this work, L‐asparagine (Asn), an amino acid derivative, has been used as a doping agent to prepare nitrogen‐ doped reduced graphene oxide gels (N‐GAs). The 3D interconnected structure gives rise to the superior electrochemical properties for supercapacitor and electrocatalytic oxygen reduction reaction (ORR). The N‐GA‐4 (the mass ratio of Asn to graphene oxide (GO) is 4 : 1 by hydrothermal method) electrode shows the capacitance of 291.6 F·g–1 at 0.5 A·g–1. Meanwhile, the assembled symmetric supercapacitor achieves a maximum energy density of 23.8 Wh· kg–1 when the power density is 451.2 W·kg–1, and demonstrates an ultralong cycling life that the retention of capacitance is 99.3% after 80000 cycles. What's more, the annealed aerogel N‐GA‐4‐900 exhibits an onset potential (Eonset) of 0.95 V, half wave potential (E1/2) of 0.84 V (vs. RHE) and the oxygen reduction current density of 5.5 mA·cm–2 at 0.1 V with nearly four‐electron transfer, which are superior to commercial Pt/C. This work offers a new insight into the synthesis and applications of N‐GAs materials towards high performance in supercapacitors and ORR.
Poly(o‐xylylene)s via Cobalt‐Catalyzed Reductive Polymerization†
Authors: Chen Si , Zhao Yanchuan
Published: March 2020

Summary of main observation and conclusion

Poly(p‐xylylene)s (PPX) have found wide applications in various fields owing to their chemical robustness, low gas permeability and excellent dielectric properties. As a structural isomer of PPX, poly(o‐xylylene)s (POX), possessing a distinct main‐chain connectivity, are excellent candidates to pursue high‐performance materials; however, the investigation of POX is hampered by the lack of efficient synthetic methods. Herein, we report a straightforward way to access POXs through a cobalt‐catalyzed reductive polymerization. This method not only allows the direct preparation of electronically unmodified POXs, but also enables the copolymerization between o‐xylylene dibromides bearing different aryl or benzylic substituents. The glass transition temperatures of the copolymers can be finely tuned by varying the ratio between comonomers. The obtained POXs are solvent processible and amenable for thin‐film fabrication. As aryl bromide moiety remains untouched during the polymerization, post‐polymerization functionalization is easily achieved through Suzuki‐Miyaura coupling reaction. The chemistry also enables the copolymerization of xylylene dibromide regioisomers, thereby leading to diversified non‐conjugated polymers, whose backbones are rich in arylene moieties. Moreover, the use of the polymerization strategy to synthesize structurally novel porous polymers is demonstrated.