bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electronic and chemical changes in shocked liquid carbon disulfide inferred from time resolved reflection experiments and analysis
Authors: Gustavsen R. , Gupta Y. M. 
Published: July 2002

Time resolved, spectroscopic reflection measurements (300–500 nm) have been used to examine the electronic and chemical changes in liquid carbon disulfide shocked to peak pressures as high as 110 kbar. Multiple-shock loading and unloading and double-shock experiments were performed to examine the influence of temperature, and to compare the present data with previous absorption and continuum measurements. The reflectance increases markedly with pressure in multiple-shock loading experiments. At 300 nm, the reflectance increases from less than 0.33% at ambient conditions to 10% at 105 kbar. However, the reflectance changes exhibit wavelength dependence, being smaller for longer wavelengths, and are reversible upon pressure unloading. A phenomenological model was developed to calculate the complex refractive index for carbon disulfide. This model in conjunction with Fresnel’s reflection equations can be used to analyze the multiple-shock reflection and absorption data in a consistent manner. The experimental results can be understood in terms of the growth of absorption bands due to increasing overlap of the π electron wave functions of neighboring molecules due to compression; this overlap is likely a precursor to associative chemical reactions.
The complete reversal in reflectance at pressures above 90 kbar is in contrast to the absorption data and arises because the present reflection measurements do not sample the bulk material, but, instead, are collected from a very thin, cooled, unreacted layer of carbon disulfide. The double-shock experiments show no evidence of a chemical reaction below 90 kbar and are in agreement with multiple-shock data. At higher pressures, the double-shock experiments show evidence of chemical reactions and display a complicated reflectance history that depends markedly on the wavelength. The wavelength dependence and associated complexities in the double-shock experiments are consequences of pressure dependent changes in absorption bands, cooling due to heat conduction to the sapphire optical windows, and the temperature dependence of the reaction threshold pressure. The present work has provided a link between the absorption measurements obtained under multiple-shock loading and continuum measurements obtained under double-shock loading.
The Membrane Transport Factor TAP/p115 Cycles between the Golgi and Earlier Secretory Compartments and Contains Distinct Domains Required for Its Localization and Function
Authors: Nelson David S. , Alvarez Cecilia , Gao Ya-sheng , García-Mata Rafael , Fialkowski Elizabeth , Sztul Elizabeth 
Published: July 2002

The mammalian protein TAP/p115 and its yeast homologue Uso1p have an essential role in membrane traffic (Nakajima et al., 1991; Waters et al., 1992; Sztul et al., 1993; Rabouille et al., 1995). To inquire into the site and mechanism of TAP/p115 action, we aimed to localize it and to identify domains required for its function. We show that in interphase cells, TAP/p115 localizes predominantly to the Golgi and to peripheral structures that represent vesicular tubular clusters (VTCs) involved in ER to Golgi transport. Using BFA/ nocodazole treatments we confirm that TAP/p115 is present on ER to Golgi transport intermediates. TAP/ p115 redistributes to peripheral structures containing ERGIC-53 during a 15°C treatment, suggesting that it is a cycling protein. Within the Golgi, TAP/p115 is associated with pleiomorphic structures on the cis side of the cis-Golgi cisterna and the cis-most cisterna, but is not detected in more distal compartments of the Golgi.
TAP/p115 binds the cis-Golgi protein GM130, and the COOH-terminal acidic domain of TAP/p115 is required for this interaction. TAP/p115 interaction with GM130 occurs only in the Golgi and is not required for TAP/p115 association with peripheral VTCs. To examine whether interaction with GM130 is required to recruit TAP/p115 to the Golgi, TAP/p115 mutants lacking the acidic domain were expressed and localized in transfected cells. Mutants lacking the GM130-binding domain showed normal Golgi localization, indicating that TAP/p115 is recruited to the Golgi independently of its ability to bind GM130. Such mutants were also able to associate with peripheral VTCs. Interestingly, TAP/p115 mutants containing the GM130-binding domain but lacking portions of the NH2-terminal region were restricted from the Golgi and localized to the ER. The COOH-terminal domain required for GM130 binding and the NH2-terminal region required for Golgi localization appear functionally relevant since expression of TAP/p115 mutants lacking either of these domains leads to loss of normal Golgi morphology.
Equivalent formulae for the supremum and stability of weighted pseudoinverses
Authors: Wei Musheng 
Published: July 2002

During recent decades, there have been a great number of research articles studying interior-point methods for solving problems in mathematical programming and constrained optimization. Stewart and O’Leary obtained an upper bound for scaled pseudoinverses

sup

W
∈

P

‖
(

W

1
2

X

)

+

W

1
2

‖

2

\underset {W\in \mathcal {P} }{\text {sup}}\|(W^{\frac {1}{2}}X)^{+}W^{\frac {1}{2}}\|_{2}

of a matrix

X
X

where

P

\mathcal {P}

is a set of diagonal positive definite matrices. We improved their results to obtain the supremum of scaled pseudoinverses and derived the stability property of scaled pseudoinverses. Forsgren further generalized these results to derive the supremum of weighted pseudoinverses

sup

W
∈

P

‖
(

W

1
2

X

)

+

W

1
2

‖

2

\underset {W\in \mathcal {P} }{\text {sup}}\|(W^{\frac {1}{2}}X)^{+}W^{\frac {1}{2}}\|_{2}

where

P

\mathcal {P}

is a set of diagonally dominant positive semidefinite matrices, by using a signature decomposition of weighting matrices

W
W

and by applying the Binet-Cauchy formula and Cramer’s rule for determinants. The results are also extended to equality constrained linear least squares problems. In this paper we extend Forsgren’s results to a general complex matrix

X
X

to establish several equivalent formulae for

sup

W
∈

P

‖
(

W

1
2

X

)

+

W

1
2

‖

2

\underset {W\in \mathcal {P} }{\text {sup}}\|(W^{\frac {1}{2}}X)^{+}W^{\frac {1}{2}}\|_{2}

, where

P

\mathcal {P}

is a set of diagonally dominant positive semidefinite matrices, or a set of weighting matrices arising from solving equality constrained least squares problems. We also discuss the stability property of these weighted pseudoinverses.
On positive entire solutions to the Yamabe-type problem on the Heisenberg and stratified groups
Authors: Lu Guozhen , Wei Juncheng 
Published: July 2002

Let

G

\mathbb {G}

be a nilpotent, stratified homogeneous group, and let

X

1

X_{1}

, …,

X

m

X_{m}

be left invariant vector fields generating the Lie algebra

G

\mathcal {G}

associated to

G

\mathbb {G}

. The main goal of this paper is to study the Yamabe type equations associated with the sub-Laplacian

Δ

G

=

∑

k
=
1

m

X
k
2

(
x
)

\Delta _{\mathbb {G}} = \sum _{k=1}^m X_k^2(x)

on

G

\mathbb {G}

:

(*)

Δ

G

u
+
K
(
x
)

u

p

=
0.

\begin{equation}\tag {*} \Delta _{\mathbb {G}} u+K(x)u^{p}=0. \end{equation}

Especially, we will establish the existence, nonexistence and asymptotic behavior of positive solutions to (

∗
*

). Our results include the Yamabe type problem on the Heisenberg group as a special case, which is of particular importance and interest and also appears to be new even in this case.
Direct‐Writing of Multi‐Functional Photo‐Reduced Graphene Oxide Fabric (rGOf) at the Liquid‐Air Interface with Tunable Porosity
Authors: Shi HaoTian Harvey , Hong Sung Hwa , Naguib Hani E. 
Published: May 2022

AbstractA multi‐functional photo‐reduced graphene oxide fabric (rGOf) created through a laser direct‐write technique at the solution surface is presented. Taking advantage of the amphiphilic nature of graphene oxide (GO) and the rapid self‐assembly of GO sheets at the liquid‐air interface, a piece of rGOf can be easily produced without any binder or supporting material in an ambient environment. Without any added processing complexity or stringent sample requirements, this accessible technique creates rGOf that exhibits tuneable microscale porosity, which enables efficient surface functionalization and active material coating. Parameters, such as the GO concentration, stabilization time, laser power, printing speed, laser focus, and post‐processing steps, can lead to vastly different rGOf morphologies. The rGOf can be made into self‐standing film or transfer printed onto any desirable substrate. Herein, it is demonstrated that the rGOf platform holds tremendous potential in Joule heating, temperature sensing, humidity sensing, tactile sensing, and ammonia sensing applications.
Confined PdMo Ultrafine Nanowires in CNTs for Superior Oxygen Reduction Catalysis
Authors: He Qianqian , Xu Tengfei , Li Jiajie , Wang Jialong , Jin Chunqiao , Chen Qian , Gu Xiaokang , Wang Xingguo , Wei Juntian , Duan Huiping , Gong Yongji 
Published: May 2022

AbstractOne‐dimensional (1D) ultrafine nanowires of different materials, especially noble metals, present an enticing prospect for catalyst applications due to their numerous active sites exposed. However, the controllable synthesis and stability issues hinder their practical applications. Herein, single‐walled carbon nanotubes (SWCNTs) are adopted as the template to synthesize and stabilize ultrafine nanowires of metals. Furthermore, the oxygen reduction reaction (ORR) is employed as an application demonstration. Impressively, the as prepared PdMo nanowires exhibit a half‐wave potential of 0.923 V and the mass activity is 35 times and 130 times higher than those of commercial Pt/C and Pd/C catalysts, respectively. Because of the protection, a superior ORR durability with 50 000 cycles can be achieved. Density functional theory (DFT) calculations reveal that the SWCNTs surface can be activated by the encapsulated PdMo NWs to achieve the exclusive adsorption of O2and the following reduction reaction. In addition, PdMo NWs@SWCNTs demonstrate excellent catalytic performance as the cathode of lithium‐oxygen batteries. The cell can reach a high discharge capacity of over 10 000 mAh g−1, better than most of the former reported catalytic electrodes. The tailored design PdMo NWs@SWCNTs show widespread applications in various energy storage & conversion fields.
Thermo‐responsive topological metamorphosis in covalent‐and‐supramolecular polymer architectures
Authors: Wang Yongming , Zhang Hao , Zhang Zhaoming , Zhao Jun , Bai Ruixue , Liu Yuhang , Zhang Xinhai , Yan Xuzhou 
Published: May 2022

AbstractTopological metamorphosis represents a powerful approach to modulate the properties of polymers. However, it still remains a major challenge to achieve the tunability of bulk mechanical properties via topological transformation in supramolecular polymer systems. Herein, we couple the covalent polymer and supramolecular polymer in a single system—referred to as covalent‐and‐supramolecular polymer (CSP)—to realize a thermo‐responsive macromolecular metamorphosis. The CSP is able to topologically switch from grafted polymer to cross‐linked network by taking advantage of synergistic dynamic covalent interactions and host–guest interactions. Benefiting from the topologically structural transformation, brittleness intrinsically evolves into toughness in our CSP architectures with minimum change of their molecular compositions from furan–maleimide to anthracene–maleimide linkers. Our work demonstrates that supramolecular polymers are a promising platform to design smart materials not only due to their inherent stimuli‐responsive properties but also because of their abilities in determining bulk mechanical properties of polymers with alterable topological structures.
Rapid One‐Pot Aerobic Oxidative N‐α‐C(sp3)‐H Functionalization of Arylmethylamines to Access Tetrasubstituted Imidazoles
Authors: Kadu Vikas D. , Khadul Siddheshwar P. , Kothe Gokul J. , Mali Ganesh A. 
Published: May 2022

AbstractA simple copper catalyzed “one‐pot” process has been developed for synthesis of polysubstituted imidazoles via direct oxidative N‐α‐C(sp3)‐H functionalization of arylmethylamines. The readily available arylmethylamines as a substrate have afforded tetrasubstituted imidazoles products up to 94% yields under mild and environmentally benign conditions. The explored substrates scope with 1,2‐diketones and α‐hydroxyketones have shown great utility for synthesis of tetrasubstituted imidazoles.
S,O‐Ligand Promoted meta‐C−H Arylation of Anisole Derivatives via Palladium/Norbornene Catalysis
Authors: Sukowski Verena , van Borselen Manuela , Mathew Simon , Fernández‐Ibáñez M. Ángeles 
Published: May 2022

AbstractReversing the conventional site‐selectivity of C−H activation processes provides new retrosynthetic disconnections to otherwise unreactive bonds. Here, we report a new catalytic system based on palladium/norbornene and an S,O‐ligand for the meta‐C−H arylation of aryl ethers that significantly outperforms previously reported systems. We demonstrate the unique ability of this system to employ alkoxyarene substrates bearing electron donating and withdrawing substituents. Additionally, ortho‐substituted aryl ethers are well tolerated, overcoming the “ortho constraint”, which is the necessity to have a meta‐substituent on the alkoxyarene to achieve high reaction efficiency, by enlisting novel norbornene mediators. Remarkably, for the first time the monoarylation of alkoxyarenes is achieved efficiently enabling the subsequent introduction of a second, different aryl coupling partner to rapidly furnish unsymmetrical terphenyls. Further insight into the reaction mechanism was achieved by isolation and characterization of some Pd‐complexes—before and after meta C−H activation—prior to evaluation of their respective catalytic activities.
Electrostatic‐Induced Crystal‐Rearrangement of Porous Organic Cage Membrane for CO2 Capture
Authors: Qu Kai , Xu Jipeng , Dai Liheng , Wang Yixing , Cao Hongyan , Zhang Dezhu , Wu Yulin , Xu Weiyi , Huang Kang , Lian Cheng , Guo Xuhong , Jin Wanqin , Xu Zhi 
Published: May 2022

AbstractPorous Organic Cages (POCs) with tunable tailoring chemistry properties and polymer‐like processing conditions are of great potential for molecular selective membranes, but it remains challenging in the assembly of high crystalline POCs with regular nanochannels for effective molecular sieving. Here we report an electrostatic‐induced crystal‐rearrangement strategy for the design of a POC membrane with heterostructure. Due to electrostatic attraction, ionic liquid molecules induced cage molecules to rearrange into a sub‐10 nm uniform and defect‐free crystal layer, which displayed competitive CO2 separation performance. The optimized hetero‐structured membrane exhibited an attractive CO2/N2 separation selectivity of over 130, which was superior to the state‐of‐the‐art membranes, accompanied with excellent long‐term and thermal shock stability. This strategy provides a new inspiration for the preparation of crystal‐rearranged membranes with regular channels for gas molecule sieving.
Sirtuin‐Derived Covalent Binder for the Selective Recognition of Protein Crotonylation
Authors: Ji Yanli , Sun Lin , Chen Yao , Qin Hongqiang , Xuan Weimin 
Published: May 2022

AbstractLysine crotonylation (Kcr) is increasingly recognized as a key protein post‐translational modification. However, selective detection and enrichment of crotonylated proteins remains a challenging task. Herein we present a covalent binder for the selective recognition of protein crotonylation. Based on proximity‐induced crosslinking, a bacterial sirtuin (CobB) was remodeled with genetically installed thiol‐bearing noncanonical amino acids at the Kcr‐interacting site, which subsequently could react with Kcr sites in a unique NAD+‐dependent manner. The covalent binder has been used to selectively recognize crotonylated proteins in extracted histone samples and in fixed cells.
Electrochemical Preparation of Porous Organic Polymer Films for High‐Performance Memristors
Authors: Tao You , Liu Hui , Kong Hui‐Yuan , Wang Tian‐Xiong , Sun Huijuan , Li Yong Jun , Ding Xuesong , Sun Lianfeng , Han Bao‐Hang 
Published: May 2022

AbstractPorous organic polymer films (PFs) with intrinsical porosity and tuneable pore environment are ideally suited for application in electronic devices. However, the huge challenges still exist for construction of electronic devices based on PFs owing to lack of robustness, processability, and controllable preparation. Herein, we report the electrochemical preparation of carbazole‐based porous organic polymer films (eCPFs) as switchable materials for the memristors. These eCPFs possess the characteristics of controllable thickness/size, high stability, and excellent porosity. Carbazole and cyano groups are introduced into the eCPFs to constructing electron transfer systems. Thus, the memristors constructed based on these eCPFs exhibit excellent switching performance, reliability, and reproducibility. The electrochemically controllable preparation method of porous organic polymer membranes proposed in this paper provides a feasible idea for the developments of electronic devices.
Diastereodivergent Synthesis of Cyclopentyl Boronic Esters Bearing Contiguous Fully Substituted Stereocenters
Authors: Fairchild Molly E. , Noble Adam , Aggarwal Varinder K. 
Published: May 2022

AbstractThe synthesis of molecules bearing two or more contiguous, quaternary stereocenters is challenging, owing to the difficulty in controlling stereochemistry whilst simultaneously constructing a sterically congested motif. Herein, we report the electrophile‐induced ring contractive 1,2‐metallate rearrangement of 6‐membered cyclic alkenyl boronate complexes for the synthesis of cyclopentyl boronic esters bearing two contiguous, fully substituted stereocenters with high levels of stereocontrol. Remarkably, simple variation of the reaction solvent enabled their diastereodivergent construction with facile access to complementary diastereomeric pairs. The utility of our methodology is demonstrated in the asymmetric total synthesis of (+)‐herbertene‐1,14‐diol.
Electrocatalytic Reduction of CO2 to Ethanol at Close to Theoretical Potential via Engineering Abundant Electron‐Donating Cuδ+ Species
Authors: Guo Chengying , Guo Yihe , Shi Yanmei , Lan Xianen , Wang Yuting , Yu Yifu , Zhang Bin 
Published: May 2022

AbstractElectrochemical CO2 reduction to liquid multi‐carbon alcohols provides a promising way for intermittent renewable energy reservation and greenhouse effect mitigation. Cuδ+ (0<δ<1) species on Cu‐based electrocatalysts can produce ethanol, but the in situ formed Cuδ+ is insufficient and easily reduced to Cu0. Here a Cu2S1−x catalyst with abundant Cuδ+ (0<δ<1) species is designedly synthesized and exhibited an ultralow overpotential of 0.19 V for ethanol production. The catalyst not only delivers an outstanding ethanol selectivity of 86.9 % and a Faradaic efficiency of 73.3 % but also provides a long‐term stability of Cuδ+, gaining an economic profit based on techno‐economic analysis. The calculation and in situ spectroscopic results reveal that the abundant Cuδ+ sites display electron‐donating ability, leading to the decrease of the reaction barrier in the potential‐determining C−C coupling step and eventually making the applied potential close to the theoretical value.
Spontaneous Resolution of Helical Building Blocks through the Formation of Homochiral Helices in Two Dimensions
Authors: Lin Xiang , Kou Bohan , Cao Jinlian , Weng Peimin , Yan Xiaosheng , Li Zhao , Jiang Yun‐Bao 
Published: May 2022

AbstractSpontaneous resolution leading to conglomerate crystals remains a significant challenge. Here we propose the formation of orthogonal homochiral supramolecular helices in at least two dimensions to allow spontaneous resolution. We suggest the design rationale that the chiral species is made into helical building blocks to allow the helix formation. As a proof‐of‐concept, acetylalanine was made into a helical short azapeptide, its N‐amidothiourea derivative containing a β‐turn structure, to which a halogen atom was further introduced at the phenylthiourea aromatic ring. The resultant folded species undergoes both intermolecular hydrogen and halogen bonding across the turn structure to form orthogonal intermolecular hydrogen‐bonded and halogen‐bonded supramolecular helices in two dimensions, and undergoes chiral resolution upon crystallization. Meanwhile, counterparts containing either an F‐substituent with weak halogen bonding or no halogen atom crystallize as racemic compounds.
Mesoporous Polyimide‐Linked Covalent Organic Framework with Multiple Redox‐Active Sites for High‐Performance Cathodic Li Storage
Authors: Yang Xiya , Gong Lei , Liu Xiaolin , Zhang Pianpian , Li Bowen , Qi Dongdong , Wang Kang , He Feng , Jiang Jianzhuang 
Published: May 2022

AbstractCovalent organic frameworks (COFs) are gaining increasing attention as renewable cathode materials for Li‐ion batteries. However, COF electrodes reported so far still exhibit unsatisfying capacity due to their limited active site density and insufficient utilization. Herein, a new two‐dimensional polyimide‐linked COF, HATN‐AQ‐COF with multiple redox‐active sites for storing Li+ions, was designed and fabricated from a new module of 2,3,8,9,14,15‐hexacarboxyl hexaazatrinaphthalene trianhydrides with a 2,6‐diaminoanthraquinone linker. HATN‐AQ‐COF possessing excellent stability, good conductivity, and a large pore size of 3.8 nm enables the stable and fast ion transport. This, in combination with the abundant redox active sites, results in a high reversible capacity of 319 mAh g−1at 0.5 C (1 C=358 mA g−1) for the HATN‐AQ‐COF electrode with a high active site utilization of 89 % and good cycle performance, representing one of the best performances among the reported COF electrodes.
A Cobalamin‐Dependent Radical SAM Enzyme Catalyzes the Unique Cα‐Methylation of Glutamine in Methyl‐Coenzyme M Reductase
Authors: Gagsteiger Jana , Jahn Sören , Heidinger Lorenz , Gericke Lukas , Andexer Jennifer N. , Friedrich Thorsten , Loenarz Christoph , Layer Gunhild 
Published: May 2022

AbstractMethyl‐coenzyme M reductase, which is responsible for the production of the greenhouse gas methane during biological methane formation, carries several unique posttranslational amino acid modifications, including a 2‐(S)‐methylglutamine. The enzyme responsible for the Cα‐methylation of this glutamine is not known. Herein, we identify and characterize a cobalamin‐dependent radical SAM enzyme as the glutamine C‐methyltransferase. The recombinant protein from Methanoculleus thermophilus binds cobalamin in a base‐off, His‐off conformation and contains a single [4Fe‐4S] cluster. The cobalamin cofactor cycles between the methyl‐cob(III)alamin, cob(II)alamin and cob(I)alamin states during catalysis and produces methylated substrate, 5′‐deoxyadenosine and S‐adenosyl‐l‐homocysteine in a 1 : 1 : 1 ratio. The newly identified glutamine C‐methyltransferase belongs to the class B radical SAM methyltransferases known to catalyze challenging methylation reactions of sp3‐hybridized carbon atoms.