bluuebunny/crossref_metadata_2025 huggingface dataset:
A Universal Strategy for Improving the Energy Transmission Efficiency and Load Power of Triboelectric Nanogenerators
Authors: Gao Fangfang , Zhang Zheng , Liao Qingliang , Zhang Guangjie , Kang Zhuo , Zhao Xuan , Xun Xiaochen , Zhao Zening , Xu Liangxu , Xue Lingfang , Zhang Yue
Published: August 2019

Triboelectric nanogenerators (TENGs) have recently been invented as a potential energy technology for harvesting low‐frequency mechanical energy. The load power acquired from a TENG is far less than the maximum output power of the TENG for the large internal impedance and impedance mismatch, and this difference results in an extremely low energy transmission efficiency. Here, a universal strategy is proposed for improving the energy transmission efficiency and load power through dielectric material design, including a reduction in the effective thickness and the directional alignment of the electric dipole. This strategy reduces the internal impedances of TENGs with different modes and results in the improvement of energy transmission efficiency and load power. According to this strategy, the internal impedance of an as‐fabricated TENG is reduced from 16 to 1.3 MΩ, and the energy transmission efficiency is enhanced from 22.46% to 99.5%. Moreover, the load power under 1 MΩ resistance is improved from 0.014 to 0.251 µW, an increase of 18 times. The strategy not only opens a universal and new road to power management, but also paves the way for the industrial applications of TENGs.
Boosting the Activity of BaCo0.4Fe0.4Zr0.1Y0.1O3−δ Perovskite for Oxygen Reduction Reactions at Low‐to‐Intermediate Temperatures through Tuning B‐Site Cation Deficiency
Authors: Kuai Xu , Yang Guangming , Chen Yubo , Sun Hainan , Dai Jie , Song Yufei , Ran Ran , Wang Wei , Zhou Wei , Shao Zongping
Published: August 2019

Doped perovskite oxides with the general formula of AxA′1−xByB′1−yO3 have been extensively exploited as the cathode materials of solid oxide fuel cells (SOFCs), but the performance at low‐to‐medium temperatures still needs improvement. BaCo0.4Fe0.4Zr0.1Y0.1O3−δ (BCFZY) has been recently reported to show promising oxygen reduction reaction (ORR) activity under SOFCs' operating conditions. Here, it is reported that the activity of BCFZY can be further boosted via introducing a slight B‐site cation deficiency into the oxide lattice, and such an improvement is assigned to an increase in oxygen mobility that brings enhancement in both surface exchange and bulk diffusion kinetics. Specifically, materials with the nominal composition of Ba(Co0.4Fe0.4Zr0.1Y0.1)0.975O3−δ and Ba(Co0.4Fe0.4Zr0.1Y0.1)0.95O3−δ show significantly improved activity for ORR at reduced temperatures with the area specific resistances of 0.011 and 0.024 Ω cm2 at 600 °C, as a comparison of 0.042 Ω cm2 for the cation stoichiometric BCFZY. Excessive B‐site deficiencies, however, lead to the formation of impurity phases, which cause a block for charge transfer and, consequently, a reduction in electrode performance. Introducing a B‐site cation deficiency is a promising way to optimize the activity of perovskite oxides for ORR at reduced temperatures, but the degree of deficiency shall be carefully tuned.
Absorption and regeneration studies of chemical solvents based on dimethylethanolamine and diethylethanolamine for carbon dioxide capture
Authors: Baltar Alberto , Gómez‐Díaz Diego , Navaza José M. , Rumbo Antonio
Published: August 2019

Present research work analyses a new chemical solvents based on the use of two tertiary amines (dimethylethanolamine and diethylethanolamine) for carbon dioxide (CO2) capture by chemical absorption taking into account the absorption behavior and the solvent regeneration degree. Regarding the first study, the absorption rate is related with the reaction mechanism at different CO2 loading. Other type of influences such as the type and amine concentration, and gas flow rate fed to the contactor were studied. In relation with solvent regeneration, several experimental procedures have been employed in order to avoid the negative characteristics of loaded‐solvent stripping. The results show the important weight of amines acidity constant upon the regeneration yield.
Dynamic Control of Chiral Space Through Local Symmetry Breaking in a Rotaxane Organocatalyst
Authors: Dommaschk Marcel , Echavarren Javier , Leigh David A. , Marcos Vanesa , Singleton Thomas A.
Published: August 2019

We report on a switchable rotaxane molecular shuttle that features a pseudo‐meso 2,5‐disubstituted pyrrolidine catalytic unit on the axle whose local symmetry is broken according to the position of a threaded benzylic amide macrocycle. The macrocycle can be selectively switched (with light in one direction; with catalytic acid in the other) with high fidelity between binding sites located to either side of the pyrrolidine unit. The position of the macrocycle dictates the facial bias of the rotaxane‐catalyzed conjugate addition of aldehydes to vinyl sulfones. The pseudo‐meso non‐interlocked thread does not afford significant selectivity as a catalyst (2–14 % ee), whereas the rotaxane affords selectivities of up to 40 % ee with switching of the position of the macrocycle changing the handedness of the product formed (up to 60 % Δee).
Colloidal Synthesis and Optical Properties of All‐Inorganic Low‐Dimensional Cesium Copper Halide Nanocrystals
Authors: Cheng Pengfei , Sun Lei , Feng Lu , Yang Songqiu , Yang Yang , Zheng Daoyuan , Zhao Yang , Sang Youbao , Zhang Ruiling , Wei Donghui , Deng Weiqiao , Han Keli
Published: August 2019

Low‐dimensional metal halides have recently attracted extensive attention owing to their unique structure and photoelectric properties. Herein, we report the colloidal synthesis of all‐inorganic low‐dimensional cesium copper halide nanocrystals (NCs) by adopting a hot‐injection approach. Using the same reactants and ligands, but different reaction temperatures, both 1D CsCu2I3 nanorods and 0D Cs3Cu2I5 NCs can be prepared. Density functional theory indicates that the reduced dimensionality in 1D CsCu2I3 compared to 0D Cs3Cu2I5 makes the excitons more localized, which accounts for the strong emission of 0D Cs3Cu2I5 NCs. Subsequent optical characterization reveals that the highly luminescent, strongly Stokes‐shifted broadband emission of 0D Cs3Cu2I5 NCs arises from the self‐trapped excitons. Our findings not only present a method to control the synthesis of low‐dimensional cesium copper halide nanocrystals but also highlight the potential of 0D Cs3Cu2I5 NCs in optoelectronics.
Single‐Crystal Cobalt Phosphate Nanosheets for Biomimetic Oxygen Evolution in Neutral Electrolytes
Authors: Shao Yue , Xiao Xue , Zhu Yun‐Pei , Ma Tian‐Yi
Published: August 2019

To improve energy conversion efficiency, the development of active electrocatalysts with similar structural features to photosynthesis II systems (PS‐II), which can efficiently catalyze the oxygen evolution reaction (OER), have received great research interest. Crystalline cobalt phosphate nanosheets are designed as an efficient OER catalyst in neutral media, showing outstanding performance that even outperforms the noble RuO2 benchmark. The correlation of experimental and computational results reveals that the active sites are the edge‐sharing CoO9 structural motif, akin to the molecular geometry of PS‐II. This unique structure can facilitate reaction intermediate adsorption and decrease the reaction energy barrier, thus improving the OER kinetics.
Magnesium Cyanide or Isocyanide?
Authors: Ballmann Gerd , Elsen Holger , Harder Sjoerd
Published: August 2019

Preference for the binding mode of the CN− ligand to Mg (Mg−CN vs. Mg−NC) is investigated. A monomeric Mg complex with a terminal CN ligand was prepared using the dipyrromethene ligand MesDPM which successfully blocks dimerization. While reaction of (MesDPM)MgN(SiMe3)2 with Me3SiCN gave the coordination complex (MesDPM)MgN(SiMe3)2⋅NCSiMe3, reaction with (MesDPM)Mg(nBu) led to (MesDPM)MgNC⋅(THF)2. A Mg−NC/Mg−CN ratio of ≈95:5 was established by crystal‐structure determination and DFT calculations. IR studies show absorbances for CN stretching at 2085 cm−1 (Mg−NC) and 2162 cm−1 (Mg−CN) as confirmed by 13C labeling. In solution and in the solid state, the CN ligand rotates within the pocket. The calculated isomerization barrier is only 12.0 kcal mol−1 and the 13C NMR signal for CN decoalesces at −85 °C (Mg−NC: 175.9 ppm, Mg−CN: 144.3 ppm). Experiment and theory both indicate that Mg complexes with the CN− ligand should not be named cyanides but are more properly defined as isocyanides.
Transfer and Amplification of Chirality Within the “Ring of Fire” Observed in Resonance Raman Optical Activity Experiments
Authors: Li Guojie , Kessler Jiří , Cheramy Joseph , Wu Tao , Poopari Mohammad Reza , Bouř Petr , Xu Yunjie
Published: August 2019

We report extremely strong chirality transfer from a chiral nickel complex to solvent molecules detected as Raman optical activity (ROA). Electronic energies of the complex were in resonance with the excitation‐laser light. The phenomenon was observed for a wide range of achiral and chiral solvents. For chiral 2‐butanol, the induced ROA was even stronger than the natural one. The observations were related to so‐called quantum (molecular) plasmons that enable a strong chiral Rayleigh scattering of the resonating complex. According to a model presented here, the maximal induced ROA intensity occurs at a certain distance from the solute, in a three‐dimensional “ring of fire”, even after rotational averaging. Most experimental ROA signs and relative intensities could be reproduced. The effect might significantly increase the potential of ROA spectroscopy in bioimaging and sensitive detection of chiral molecules.
Monophosphine‐substituted diiron azadithiolate complexes: New syntheses, characterization and electrochemical properties
Authors: Wang Zheng , He Jiao , Lü Shuang , Jiang Wei‐Dong , Wu Yu , Jiang Jin , Xie Ying , Mu Chao , Li Ao , Li Yu‐Long , Li Qian‐Li
Published: August 2019

Investigating the synthesis and properties of diiron azadithiolate complexes is one of the key topics for mimicking the active site of [FeFe]‐hydrogenases, which might be very useful for the design of new efficient catalysts for hydrogen production and the development of a future hydrogen economy. A series of new phosphine‐substituted diiron azadithiolate complexes as models for the active site of [FeFe]‐hydrogenases are described. A novel and efficient way was firstly established for the preparation of phosphine‐substituted diiron azadithiolate complexes. The reaction of Fe2(μ‐SH)2(CO)6 and phosphine ligands L affords the intermediate Fe2(μ‐SH)2(CO)5L (A). The intermediate reacts in situ with a premixed solution of paraformaldehyde and ammonium carbonate to produce the target phosphine‐substituted diiron azadithiolate complexes Fe2[(μ‐SCH2)2NH](CO)5L (1a–1f) (L = P(C6H4–4‐CH3)3, P(C6H4–3‐CH3)3, P(C6H4–4‐F)3, P(C6H4–3‐F)3, P(2‐C4H3O)3, PPh2(OCH2CH3)). Furthermore, reactions of the intermediate A with I‐4‐C6H4N(CH2Cl)2 in the presence of Et3N give the phosphine‐substituted diiron azadithiolate complexes Fe2[(μ‐SCH2)2NC6H4–4‐I](CO)5L (2a–2e) (L = P(C6H4–4‐CH3)3, P(C6H4–3‐CH3)3, P(C6H4–4‐F)3, P(C6H4–3‐F)3, P(2‐C4H3O)3). All the complexes were fully characterized using elemental analysis, IR and NMR spectroscopies and, particularly for 1a, 1c–1e, 2a and 2c, single‐crystal X‐ray diffraction analysis. In addition, complexes 1a–1f and 2a–2e were found to be catalysts for H2 production under electrochemical conditions. Density functional theory calculations were performed for the reactions of Fe2(μ‐SH)2(CO)6 + P(C6H4–4‐CH3)3.
In situ synthesis, structure, and properties of a dendritic branched nano‐thickening agent for high temperature fracturing fluid
Authors: Tang Jun , Li Haibo , Yan Shengdong , Yan Siming
Published: August 2019

The aim of this work was to prepare a novel dendritic branched nano‐thickening agent by free radical polymerization of acrylamide (AM), acrylic acid (AA), sodium p‐styrene sulfonate, dimethyl diallyl ammonium chloride, and multiwalled carbon nanotubes. The as‐synthesized nano‐thickening agent was characterized by Fourier transform infrared, Raman spectra, transmission electron microscope, 1H‐NMR, and thermogravimetric analysis (TGA). Compared with the pristine polymer and partially hydrolyzed polyacrylamide (HPAM), thickening capacity, temperature resistance, and salt tolerance properties of the nano‐thickening agent considerably improved, and the viscosity of 0.5% nano‐polymer solution was 126.5 mPa·s. Additionally, the properties of the nano‐gel prepared by nano‐thickener, such as temperature and shear tolerance, viscoelasticity, sand carrying capacity, and gel breaking performance, were evaluated showing the satisfactory performance of the nano‐gel under high temperature condition. The results indicated that the nano‐thickener has potential applications in the field of oil and gas production. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48446.
Integrated design of robust fault estimation and fault‐tolerant control against simultaneous actuator and sensor faults
Authors: Mu Yunfei , Zhang Huaguang , Zhang Kun , Ren He
Published: August 2019

This paper investigates the problems of simultaneous actuator and sensor faults estimation, as well as the fault‐tolerant control scheme for a class of linear continuous‐time systems subject to external disturbances. First, the original system is transformed into a singular form by extending the actuator fault and sensor fault to be parts of the new state. Then, a new estimation technique named non‐fragile proportional‐derivative observer is designed for the singular system to achieve simultaneous estimations of states and faults. With the obtained estimations information, an integrated design of the non‐fragile output feedback fault‐tolerant controller is explored to compensate for the effect of faults by stabilizing the closed‐loop system. Finally, a simulation study on a two‐stage chemical reactor with recycle streams is provided to verify the effectiveness of the proposed approach.
Modelling and simulation of nabla fractional dynamic systems with nonzero initial conditions
Authors: Wei Yiheng , Wang Jiachang , Tse Peter W. , Wang Yong
Published: August 2019

The paper focuses on the numerical approximation of discrete fractional order systems with the conditions of nonzero initial instant and nonzero initial state. First, the inverse nabla Laplace transform is developed and the equivalent infinite dimensional frequency distributed model of discrete fractional order system is introduced. Then, resorting the nabla discrete Laplace transform, the rationality of the finite dimensional frequency distributed model approaching the infinite one is illuminated. Based on this, an original algorithm to estimate the parameters of the approximate model is proposed with the help of vector fitting method. Additionally, the applicable object is extended from a sum operator to a general system. Three numerical examples are performed to illustrate the applicability and flexibility of the introduced methodology.
Social‐media use and academic performance among undergraduates in biology
Authors: Shen Jie
Published: August 2019

The development of social media applications has made it an important part of students' personal lives. In this article, we aim to determine whether social media usage is beneficial or harmful to college students through academic performance. Through a survey of biological undergraduates, we found that boys use social media applications more frequently than girls, and that GPA is inversely related to the number of social media applications that students subscribe to. In addition, we found that using more social media applications is positively related to the amount of time spent on social media per day. Our research shows that social media may have a negative impact on undergraduates’ study habits and academic performance. © 2019 International Union of Biochemistry and Molecular Biology, 47(6):615–619, 2019.
Simultaneous determination of polyphenols and triterpenes in pomegranate peel based on high‐performance liquid chromatography fingerprint by solvent extraction and ratio blending method in tandem with wavelength switching
Authors: Ding Wenzheng , Wang Hanxue , Zhou Quan , Wu Chao , Gao Xiaoli , Cheng Xuemei , Tian Li , Wang Changhong
Published: August 2019

Traditionally, pomegranate (Punica granatum L.) has been consumed as fresh fruit or as pomegranate juice. Pomegranate peel, the dried husk of P· granatum, is an important herbal medicine for treating diarrhea, hemostasis and insect‐induced abdominal pain in China. However, the quality control methods for pomegranate peel remain unsatisfactory. In this work, a new HPLC‐based qualitative and quantitative method for quality control of pomegranate peel was developed and validated for the simultaneous determination of polyphenols and triterpenes (including punicalagins A and B, ellagic acid, oleanolic acid and ursolic acid) by solvent extraction and ratio blending method in tandem with wavelength switching. The average recoveries were 98.07–100.61% with relative standard deviation no more than 4.27%. In addition, the fingerprint analysis was conducted to interpret the consistency of the quality test. Thirteen characteristic peaks were selected to evaluate the similarities of 16 batches of pomegranate peel. The similarities of samples were all more than 0.80, indicating that the samples from different areas of China were consistent. The results demonstrated that quantitative analysis and the HPLC fingerprint as a characteristic distinguishing method combining similarity evaluation can be successfully used to assess the quality and to identify the authenticity of pomegranate peel.
Development, validation and comparison of four methods for quantifying endogenous 25OH‐D3 in human plasma
Authors: Li Yan‐yan , Jiang Yi , Liu Li , Guo Hai‐yang , Cao Hai‐wei , Ji Zheng‐chao
Published: August 2019

To meet the increasing clinical needs for 25‐hydroxyvitamin D3 (25OH‐D3) detection, the development of an efficient and accurate high‐performance liquid chromatography–mass spectrometry (HPLC–MS) method for plasma 25OH‐D3 quantitation is important. Since 25OH‐D3 is an endogenous compound, the lack of a plasma blank increases the difficulty of accurately quantifying 25OH‐D3. Selection of a method suitable for clinical monitoring among various methods for endogenous compound quantification is necessary. Methyl tert butyl ether was chosen for the sample treatment in a liquid–liquid extraction protocol. Water as a blank matrix, 5% human serum albumin in water as a blank matrix, surrogate analyte and background subtraction were designed to address the problem of a deficiency of a plasma blank. Four liquid chromatography–tandem mass spectrometry methods were fully validated to verify the advantages and limitations owing to regulatory deficiencies for endogenous compound validation. All four methods met the criteria and could be used to monitor clinical samples. Overall 30 human plasma samples were quantified in parallel using the four methods. The difference between any two methods was <12.6% and the total relative standard deviation was <5.2%. Background subtraction and 5% human serum albumin in water as a blank matrix may be better choices considering data quality, matrix similarity, cost and practicality.
Demonstration of exogenous nuclear histone H3 binding to mitochondria and subsequent cytochrome c release in cauliflower
Authors: Major Linda A. , Sauterer Roger
Published: August 2019

The life cycle of a cell is partly regulated by the programmed cell death (PCD) process. From development to demise, a cell's PCD process must respond to external signals and internal factors mediated by mitochondria. Previous studies show that the release of histones into the cytosol caused by DNA damage or loss of nuclear integrity is correlated with apoptosis in mammalian cells. These released histones bind to mitochondria and permeabilize its inner and outer membranes, which causes the release of cytochrome c into the cytosol that leads to caspase activation and the demise of the cell. Owing to the high conservation of histones, we hypothesize that histone‐mediated cytochrome c release from mitochondria may be conserved across a wide range of eukaryotes. We investigated this histone–mitochondrial interaction in cauliflower using density‐gradient purified mitochondria and exogenous histones from a crude histone fraction, then added the exogenous histone fractions to the purified cauliflower mitochondria and analyzed the mitochondrial pellets and supernatants by immunoblotting against cytochrome c and H3. Our data clearly shows that histone‐enriched fractions elicited cytochrome c release from mitochondria, and that mitochondria bind exogenous histone H3.
P‐Type Boron‐Doped Monolayer Graphene with Tunable Bandgap for Enhanced Photocatalytic H2 Evolution under Visible‐Light Irradiation
Authors: Wu Yujun , Han Zhanli , Younas Waqar , Zhu Youqi , Ma Xilan , Cao Chuanbao
Published: August 2019

Graphene‐based materials are considered as one of the promising photocatalysts for hydrogen production from solar‐driven water splitting yet subject to zero bandgap limitation. Here, we report an efficient one‐step pyrolysis for preparing p‐type boron‐doped monolayer graphene. Through varying the dopant content, the bandgap of the boron‐doped graphene can be tuned. Moreover, a p‐type conductivity behavior of the boron‐doped monolayer graphene is demonstrated by the four‐probe measurement and Hall effect measurement. The boron‐doped graphene can service as an efficient semiconductor photocatalyst for hydrogen production from water splitting under visible‐light irradiation. The optimized boron‐doped graphene can deliver a high H2 production rate of 219.3 μmol h−1 g−1 without any cocatalyst. The photocatalyst can be recycled at least four times without obvious activity decay and maintain high H2 production rate of 215.3 μmol h−1 g−1 after 60 h reaction, indicative of excellent stability. This work may open up a new avenue for fabrication of new photocatalysts based on p‐type boron‐doped monolayer graphene.
The Stereoselective Formation of trans‐Cumulene through Dehalogenative Homocoupling of Alkenyl gem‐Dibromides on Cu(110)
Authors: Cai Liangliang , Kang Faming , Sun Qiang , Gao Wenze , Yu Xin , Ma Honghong , Yuan Chunxue , Xu Wei
Published: August 2019

Stereoselective synthesis of geometrically pure isomers is challenging and important in a variety of chemistry related disciplines and applications. The recently developed on‐surface synthesis strategy provides us opportunities in the fabrication of specific nanostructures which remain challenging by conventional solution chemistry. In this work, we choose alkenyl gem‐dibromides as molecular precursors, and demonstrate the formation of specific trans‐cumulene products via C−C couplings on Cu(110). This study supplements the database of on‐surface synthesis strategies by introducing the alkenyl gem‐dibromide group on the surface. More importantly, it provides a way to stereoselective synthesis of specific isomers involving C−C double bonds, which may be of substantial utility in stereochemistry.
Cobalt Nanoparticles Apically Encapsulated by Nitrogen‐doped Carbon Nanotubes for Oxidative Dehydrogenation and Transfer Hydrogenation of N‐Heterocycles
Authors: Xu Dan , Zhao Hong , Dong Zhengping , Ma Jiantai
Published: August 2019

It is important to develop a highly active and stable transition‐metal catalyst with dual‐functional properties in the reversible transformations between various saturated and unsaturated N‐heterocycles. Herein, we prepared the cobalt nanoparticles (Co NPs) apically encapsulated by the N‐doped carbon nanotubes catalyst (Co@NCNTs) via a multiple pyrolysis of low‐cost dicyandiamide and cobalt (II) acetylacetonate. The catalyst shows excellent activity and recyclability towards the oxidative dehydrogenation (ODH) and the catalytic transfer hydrogenation (CTH) for various N‐heterocycles. The structure of outer N‐doped carbon nanotubes (NCNTs) can protect Co NPs from aggregation and leaching. Moreover, the encapsulated Co NPs and the NCNTs may generate a synergistic effect. Both of them facilitate the high performance. The poisoning tests with KSCN were to clarify the different active sites for ODH and CTH reactions: the Co NPs could modify the NCNTs through electrons redistribution, therefore the NCNTs could directly activate O2 in ODH. The encapsulated Co NPs is enhanced by the doped N atoms which is good for the H2 activation in CTH. What's more, the mechanisms of ODH and CTH reactions were also proposed. This work provides a facile and low‐cost method to design catalysts, which are dual‐functional, highly active and stable, for industrial applications.
Chemoenzymatic Synthesis of an Odanacatib Precursor through a Suzuki‐Miyaura Cross‐Coupling and Bioreduction Sequence
Authors: González‐Martínez Daniel , Gotor Vicente , Gotor‐Fernández Vicente
Published: August 2019

A series of 1‐aryl‐2,2,2‐trifluoroethanones has been chemically synthesized to later study their bioreduction using stereocomplementary alcohol dehydrogenases (ADHs). Satisfyingly, (R)‐alcohols were obtained in high conversions and selectivities using the ADH from Ralstonia species and the one from Rhodococcus ruber, while the (S)‐enantiomers were independently produced using the ADH from Lactobacillus brevis and the commercially available evo‐1.1.200. In the search for a stereoselective route towards the Odanacatib, an orally bioavailable and selective inhibitor of Cathepsin K, the development of a sequential methodology combining a palladium‐catalyzed cross coupling between 1‐(4‐bromophenyl)‐2,2,2‐trifluoroethanone and 4‐(methylsulfonyl)phenylboronic acid in aqueous medium with the bioreduction of the resulting 2,2,2‐trifluoro‐1‐(4′‐(methylsulfonyl)‐[1,1′‐biphenyl]‐4‐yl)ethanone has been extensively studied. Finally, the desired (R)‐2,2,2‐trifluoro‐1‐(4′‐(methylsulfonyl)‐[1,1′‐biphenyl]‐4‐yl)ethanol was obtained in enantiomerically pure form and 85 % yield with a 128 g L−1 d−1 productivity following a sequential approach.
Iterative deflation algorithm, eigenvalue equations, and PLS2
Authors: Stocchero Matteo
Published: August 2019

PLS2 is probably the most used algorithm to perform projection to latent structures regression in the case of multivariate response. However, several criticisms pointed to the theoretical limits of its original formulation, highlighting the need of a more robust foundation within the theory of regression analysis. The iterative deflation algorithm is here introduced as a starting point to obtain a family of regression methods, which includes PLS2, principal component regression (PCR), and elastic component regression (ECR), where different eigenvalue equations are used to calculate the weight vectors. Within this framework, an original portrait of PLS2 is drawn. The main mathematical properties useful to understand what PLS2 is and how PLS2 behaves are derived. A new regression method called iterative deflation algorithm‐based regression (IDAR) is introduced to describe the limit behaviour of PLS2, PCR, and ECR. The post‐transformation method is presented as a general property of the iterative deflation algorithm. Two data sets, one simulated and the other experimental, are investigated to illustrate the main properties of PLS2.
Bidirectional Hiyama–Denmark Cross‐Coupling Reactions of Bissilyldeca‐1,3,5,7,9‐pentaenes for the Synthesis of Symmetrical and Non‐Symmetrical Carotenoids
Authors: Rivas Aurea , Pérez‐Revenga Víctor , Alvarez Rosana , de Lera Angel R.
Published: August 2019

The construction of the carotenoid skeleton by Pd‐catalyzed Csp2−Csp2cross‐coupling reactions of symmetrical and non‐symmetrical 1,10‐bissilyldeca‐1,3,5,7,9‐pentaenes and the corresponding complementary alkenyl iodides has been developed. Reaction conditions for these bidirectional and orthogonal Hiyama–Denmark cross‐coupling reactions of bisfunctionalized pentaenes are mild and the carotenoid products preserve the stereochemical information of the corresponding oligoene partners. The carotenoids synthesized in this manner include β,β‐carotene and (3R,3′R)‐zeaxanthin (symmetrical) as well as 9‐cis‐β,β‐carotene, 7,8‐dihydro‐β,β‐carotene and β‐cryptoxanthin (non‐symmetrical).
Lattice Shrinkage by Incorporation of Recombinant Starmaker‐Like Protein within Bioinspired Calcium Carbonate Crystals
Authors: Różycka Mirosława , Coronado Ismael , Brach Katarzyna , Olesiak‐Bańska Joanna , Samoć Marek , Zarębski Mirosław , Dobrucki Jerzy , Ptak Maciej , Weber Eva , Polishchuk Iryna , Pokroy Boaz , Stolarski Jarosław , Ożyhar Andrzej
Published: August 2019

Invited for the cover of this issue is the group of Mirosława Różycka and Andrzej Ożyhar at the Wroclaw University of Science and Technology, and colleagues at Jagiellonian University, the Polish Academy of Sciences, and Technion Israel Institute of Technology. The image depicts confocal laser scanning images showing the effect of the protein involved in the formation of otoliths on the calcium carbonate crystal lattice reported in the paper. Read the full text of the article at 10.1002/chem.201902157.
Supramolecular Organization of Model Polycyclic Aromatic Molecules: Comparison of 2D and 3D Assemblies
Authors: Raj Gijo , Kikkawa Yoshihiro , Catalano Luca , Pasricha Renu , Norikane Yasuo , Naumov Panče
Published: August 2019

The spatial organization of polycyclic aromatic molecules during adhesion on a solid/liquid interface is the key event of a plethora of natural and industrial processes. Herein, we report the supramolecular assembly of violanthrone‐79—a model of asphaltenes, an intractable mixture of polycyclic aromatics from crude oil—at the solid‐liquid interface between highly oriented pyrolytic graphite (HOPG) and a hydrophobic medium (1‐phenyloctane). High‐resolution scanning tunneling microscopy revealed that molecules of violanthrone‐79 readily self‐assemble on the surface in supramolecular “nanoring” structures. The lattice parameters of the 2D unit cell are on the same order as those determined from a bulk single crystal. Transmission electron microscopy showed long‐range ordered patterns, and the spacing between the fringes is in agreement with the inter‐planar distances between aromatic cores of molecules that are helically arranged around the [001] axis in the 3D crystal. The results confirm that upon adsorption on solid/liquid interfaces, polycyclic aromatic molecules such as violanthrone‐79 form supramolecular assemblies by interaction with the substrate and self‐association, and this process could be the initial step of deposition of asphaltenes on carbonaceous oil reservoir walls and production tubing.
Tris(pentafluorophenyl)borane‐pyrrolo[3,2‐b]pyrrole Hybrids: Solid‐State Structure and Crystallization‐Induced Enhanced Emission
Authors: Hatanaka Sou , Ono Toshikazu , Yano Yoshio , Gryko Daniel T. , Hisaeda Yoshio
Published: August 2019

The work demonstrates that the quadrupolar nature of acceptor‐donor‐acceptor pyrrolo[3,2‐b]pyrrole systems can be substantially modified via the formation of boron‐nitrogen (B−N) bonds between peripheral CN groups and B(C6F5)3. This coordination enables a strong bathochromic shift of emission for both the solid crystalline state as well as in certain solvents. The B−N complex, or co‐crystal, was effectively isolated from the reaction between a pyrrolo[3,2‐b]pyrrole with two cyanophenyl moieties and tris(pentafluorophenyl)borane (TPFB), which were mixed in non‐polar solvents or prepared via liquid‐assisted solid‐state synthesis in a ball mill. An investigation of the structure‐property relationship confirmed that the intermolecular B−N bond influences the bathochromic shift in the absorption and emission spectra and that crystallization‐induced emission enhancement was observed owing to the benefits of the molecular packing style and the intermolecular C−H⋅⋅⋅F interactions. The postsynthetic strategy involves hybridization of molecules on a molecular level, which should provide a variety of novel photofunctional materials.
Cross‐Linked Nanocellulosic Materials and Their Applications
Authors: Liang Luna , Bhagia Samarthya , Li Mi , Huang Chen , Ragauskas Arthur J.
Published: August 2019

Nanocelluloses (NCs) have remarkable mechanical properties and contain abundant surface functional groups that can be modified or cross‐linked with other materials. They have been widely used as an environment‐friendly reinforcing agent in polymer composites. However, for applications that are carried out in humid environments or aqueous suspensions, hydrophilicity of NCs lower their mechanical integrity. Hence, cross‐linking techniques have been investigated in recent years for preparing NC‐based materials that are dimensionally stable under humid or aqueous environments and have better physicochemical properties. This Minireview examines the quickly growing field of cross‐linked NC‐based materials, which have many benefits including improved aqueous, structural, mechanical, and thermal stability. In addition, the potential application of cross‐linked NC‐based materials in adsorption of heavy metal is discussed.
A Sound Sequence to Triphenylphosphino Dibromoplatinum(II) Complexes – Solvothermal Preparation of trans‐[PtBr(µ‐Br)(PPh3)]2
Authors: Fioco David , Belli Dell'Amico Daniela , Labella Luca , Marchetti Fabio , Samaritani Simona
Published: August 2019

A sound synthetic procedure for the preparation of trans‐[PtBr(µ‐Br)(PPh3)]2 is described. The species was fully characterized and used to obtain [PtBr2(PPh3)(L)] complexes (L = DMSO, p‐toluidine, pyridine) by a bridge‐splitting reaction. All products were fully characterized by NMR spectroscopy, together with cis‐[PtBr2(PPh3)(NCCH3)], obtained as an intermediate in the synthesis of the dinuclear precursor. Cis‐[PtBr2(PPh3)(NCCH3)] was also studied by X‐ray diffraction.
Crystal Chemistry and SAXS Studies of an Octahedral Polyoxoarsenotungstate Nanocluster Encapsulating Four Unprecedented Thorium Arsenate Fragments ({Th3As2On} – n = 25 or 26)
Authors: Dufaye Maxime , Duval Sylvain , Stoclet Grégory , Loiseau Thierry
Published: August 2019

The reaction of [H‐B‐α‐AsVW9O34]8– with the 5f tetravalent thorium cation in presence of an acetate buffer and KCl at pH = 4.7 gives rise to the formation of an octahedral polyoxoarsenotungstate nanocluster [K4{Th3(H2O)3{AsO(µ2‐O)3}2}{Th3(H2O)2{AsO(µ2‐O)3}2}3(AsW10O38)6]38–. This molecule is constructed around four unprecedented {Th3As2On} (n = 25 or 26) fragments stabilized by the presence of six arsenotungstates {AsVW10O38} coming from the partial decomposition of the polyanionic {AsVW9O34} precursor. This molecular architecture was characterized by single‐crystal X‐ray diffraction and its solution behavior was evaluated by using small angle X‐ray scattering (SAXS) analyses. It shows that the molecule decomposes to form smaller 1:2 sandwich like polyanionic entities.
On the Basicity of Organic Bases in Different Media
Authors: Tshepelevitsh Sofja , Kütt Agnes , Lõkov Märt , Kaljurand Ivari , Saame Jaan , Heering Agnes , Plieger Paul G. , Vianello Robert , Leito Ivo
Published: August 2019

The basicities of simple organic bases – aliphatic and aromatic amines, amidines, phosphazenes, as well as saturated and unsaturated nitrogen heterocycles – are examined in acetonitrile, dimethyl sulfoxide, tetrahydrofuran, water and the gas phase. The basicities (pKaH values) of conjugate acids of a large variety of bases in these media are presented and discussed. Equations employing easily usable structural descriptors have been derived for approximately converting basicities from acetonitrile to other solvents. Recommendations are given on their practical use and a number of pKaH values that are experimentally unavailable are estimated from these relationships. An important part of the minireview is a large compilation of pKaH and GB values of the compounds in solvents and the gas phase, respectively, as well as the revised basicity scale in acetonitrile, now containing more than 270 pKaH values.
Air‐Induced One‐Pot Synthesis of N‐Sulfonylformamidines from Sulfonyl Chlorides, NaN3, and Tertiary/Secondary Amines
Authors: Bi Wen‐Zhu , Zhang Wen‐Jie , Li Zi‐Jie , Xia Xiao‐Yi , Chen Xiao‐Lan , Qu Ling‐Bo , Zhao Yu‐Fen
Published: August 2019

An efficient and practical one‐pot strategy for the synthesis of N‐sulfonylformamidines was developed by directly using easily available sulfonyl chlorides, sodium azide and tertiary/secondary amines in the presence of 5 mol‐% CuBr2 under aerobic oxidative conditions.
Toward hardware‐accelerated QoS‐aware 5G network slicing based on data plane programmability
Authors: Ricart‐Sanchez Ruben , Malagon Pedro , Matencio‐Escolar Antonio , Alcaraz Calero Jose M. , Wang Qi
Published: August 2019

The diverging requirements from various vertical industries have driven the paradigm shift in the next‐generation (5G) mobile networks, where network slicing has emerged as a major paradigm for this purpose by sharing and isolating resources over the same 5G physical infrastructure. To truly fulfill the different quality‐of‐service (QoS) requirements imposed by different network slices for different vertical applications, it is essential to introduce a programmable data plane that is aware of QoS and is configurable to enforce the QoS commitments. In this paper, we focus on designing, prototyping, and evaluating a novel QoS‐aware data‐plane network slicing framework for the edge and core network segments of a 5G network. The proposed framework is capable of dealing with differentiated services through hardware‐based traffic classification, priority configuration, and traffic scheduling. By leveraging the latest open‐source field‐programmable gate array platform, we prototype the proposed framework and empirically evaluate the performance of the prototyped system. Experiment results demonstrate the capabilities of the proposed framework in terms of achieving QoS‐aware network slicing at the data plane.
Geotechnische Untersuchungen an modifizierten Stahlwerksschlacken
Authors: Barka Elissavet , Birle Emanuel , Demond Derik
Published: August 2019

Anhand von umfangreichen experimentellen Laboruntersuchungen wurde gezeigt, dass Stahlwerksschlacken (SWS) durch die Zugabe von feinkörnigen Zusatzstoffen in ihrer Wasserdurchlässigkeit derart reduziert werden können, dass sie gemäß dem Merkblatt über Bauweisen für Technische Sicherungsmaßnahmen beim Einsatz von Böden und Baustoffen mit umweltrelevanten Inhaltsstoffen im Erdbau (M TS E‐Merkblatt) ohne zusätzliche Abdichtungsschichten eingesetzt werden können. Die Untersuchungen erfolgten an drei SWS, die unter Verwendung von vier feinkörnigen Zusatzstoffen granulometrisch modifiziert wurden. Die Versuchsergebnisse zeigen, dass Wasserdurchlässigkeitsbeiwerte von kf ≤ 1 ⋅ 10–8 m/s bereits bei einer Zugabemenge von 8 M.‐% feinkörnigen Zusatzstoffen erreicht werden können. Im Vergleich zu natürlichen Baustoffgemischen zeigte sich auch, dass für SWS zum Erreichen eines geringen Luftporenanteils mit einhergehender zusätzlicher Reduktion ihrer Wasserdurchlässigkeit i. d. R. eine höhere Verdichtungsenergie (modifizierte Proctorenergie) erforderlich ist und dass das Quellvermögen von natriumaktivierten Bentoniten aufgrund der Ionenkonzentration in der Porenlösung herabgesetzt werden kann.
High‐temperature CO2 removal from CH4 using silica membrane: experimental and neural network modeling
Authors: Ullah Sami , Assiri Mohammed A. , Al‐Sehemi Abdullah G. , Bustam Mohamad Azmi , Abdul Mannan Hafiz , Abdulkareem Firas A. , Irfan Ahmad , Saqib Sidra
Published: August 2019

Inorganic membranes can operate under harsh conditions. However, successful synthesis of inorganic membranes is still challenging, and its performance depends on many factors. This work reports the effect of dip‐coating duration, inlet pressure, and inlet flow rate on the flux, permeability, and selectivity of silica membranes. A silica membrane was prepared by the deposition of silica sol onto porous alumina support. The permeability test was conducted at 100 °C using a single gas of CO2 and CH4. The highest flux was observed at the maximum inlet pressure and inlet flow rate for the membrane prepared at the minimum dip‐coating duration. The neural network modeling of the membrane predicted permeabilities showed a considerably high validity regression (R ≈ 0.99) of the predicted data linked to the experimental sets. The separation factor (α) was the highest at the maximum dip‐coating duration. The synthesized silica membrane has potential for CO2/CH4 separation under harsh operating conditions. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.
Investigation and magnitude re‐evaluation of the 1955 Zheduotang earthquake, eastern Tibetan Plateau, China
Authors: Yan Bing , Wang Maomao , Jia Dong , Cui Jian
Published: August 2019

Rupture lengths and displacements of historical earthquakes are significant components of the accurate magnitude estimates required for understanding fault behaviour and earthquake recurrence patterns. Along the Xianshuihe–Xiaojiang fault system on the eastern Tibetan Plateau, 36 large historical earthquakes have been recorded during the past ~700 years, many of which still require detailed investigation. In this study, we reinvestigated the coseismic surface rupture produced by the 1955M7.5 Zheduotang earthquake. The Zheduotang Fault, which is the source fault of the 1955 event, is one of the main faults of the central Xianshuihe fault zone, with a left‐lateral strike‐slip rate of 3.4 mm/year according to our measurements and the ages of offset terraces. High‐resolution Google Earth images and field observations reveal that the surface ruptures of this earthquake were characterized by left‐lateral offsets of gullies, animal paths, alluvial terraces, and fans. The coseismic surface rupture length caused by the 1955 earthquake could be up to ~43 km, with mainly horizontal displacements of 0.6–1.7 m. Based on empirical relationships between magnitude and coseismic surface rupture length for large earthquakes, the magnitude of the 1955 Zheduotang earthquake is re‐evaluated to beMW7.0. Our study demonstrates the necessity of re‐evaluating previous magnitude estimates of historical earthquakes in western China.
Group connectivity: Z4 vs Z22
Authors: Hušek Radek , Mohelníková Lucie , Šámal Robert
Published: August 2019

We answer a question on group connectivity suggested by Jaeger et al [J. Combin. Theory, Ser. B 56 (1992), pp. 165–182]: we find that ‐connectivity does not imply ‐connectivity, neither vice versa. We use a computer to find the graphs certifying this and to verify their properties using a nontrivial enumerative algorithm (and we also use an independent implementation of a straightforward algorithm to double‐check our results). We provide a simple construction to provide an infinite family of examples. While the graphs we found are small (the largest has 15 vertices and 21 edges), a computer‐free approach remains elusive.
The rollout of Community ART Refill Groups in Zimbabwe: a qualitative evaluation
Authors: Bochner Aaron F , Meacham Elizabeth , Mhungu Nathan , Manyanga Phibion , Petracca Frances , Muserere Claudios , Gonese Gloria , Makunike Batsirai , Wazara Blessing , Gwanzura Clorata , Nyika Ponesai , Levine Ruth , Mutasa‐Apollo Tsitsi , Balachandra Shirish , Wiktor Stefan Z
Published: August 2019

Introduction

Community ART Refill Groups (CARGs) are an antiretroviral therapy (ART) delivery model where clients voluntarily form into groups, and a group member visits the clinic to collect ART for all group members. In late 2016, Zimbabwe began a nationwide rollout of the CARG model. We conducted a qualitative evaluation to assess the perceived effects of this new national service delivery model.

Methods

In March‐June 2018, we visited ten clinics implementing the CARG model across five provinces of Zimbabwe and conducted a focus group discussion with healthcare workers and in‐depth interviews with three ART clients per clinic. Clinics had implemented the CARG model for approximately one year. All discussions were audio recorded, transcribed, and translated into English, and thematic coding was performed by two independent analysts.

Results

In focus groups, healthcare workers described that CARGs made ART distribution faster and facilitated client tracking in the community. They explained that their reduced workload allowed them to provide better care to those clients who did visit the clinic, and they felt that the CARG model should be sustained in the future. CARG members reported that by decreasing the frequency of clinic visits, CARGs saved them time and money, reducing previous barriers to collecting ART and improving adherence. CARG members also valued the emotional and informational support that they received from other members of their CARG, further improving adherence. Multiple healthcare workers did express concern that CARG members with diseases that begin with minor symptoms, such as tuberculosis, may not seek treatment at the clinic until the disease has progressed.

Conclusions

We found that healthcare workers and clients overwhelmingly perceive CARGs as beneficial. This evaluation demonstrates that the CARG model can be successfully implemented on a national scale. These early results suggest that CARGs may be able to simultaneously improve clinical outcomes and reduce the workload of healthcare workers distributing ART.
Loss of tau and Fyn reduces compensatory effects of MAP2 for tau and reveals a Fyn‐independent effect of tau on calcium
Authors: Liu Guanghao , Thangavel Ramasamy , Rysted Jacob , Kim Yohan , Francis Meghan B. , Adams Eric , Lin Zhihong , Taugher Rebecca J. , Wemmie John A. , Usachev Yuriy M. , Lee Gloria
Published: August 2019

Microtubule‐associated protein tau associates with Src family tyrosine kinase Fyn and is tyrosine phosphorylated by Fyn. The presence of tyrosine phosphorylated tau in AD and the involvement of Fyn in AD has drawn attention to the tau–Fyn complex. In this study, a tau–Fyn double knockout (DKO) mouse was generated to investigate the role of the complex. DKO mice resembled Fyn KO in novel object recognition and contextual fear conditioning tasks and resembled tau KO mice in the pole test and protection from pentylenetetrazole‐induced seizures. In glutamate‐induced Ca2+ response, Fyn KO was decreased relative to WT and DKO had a greater reduction relative to Fyn KO, suggesting that tau may have a Fyn‐independent role. Since tau KO resembled WT in its Ca2+ response, we investigated whether microtubule‐associated protein 2 (MAP2) served to compensate for tau, since the MAP2 level was increased in tau KO but decreased in DKO mice. We found that like tau, MAP2 increased Fyn activity. Moreover, tau KO neurons had increased density of dendritic MAP2‐Fyn complexes relative to WT neurons. Therefore, we hypothesize that in the tau KO, the absence of tau would be compensated by MAP2, especially in the dendrites, where tau–Fyn complexes are of critical importance. In the DKO, decreased levels of MAP2 made compensation more difficult, thus revealing the effect of tau in the Ca2+ response.