bluuebunny/crossref_metadata_2025 huggingface dataset:
Black holes in the Milky Way Galaxy
Authors: Filippenko Alexei V.
Published: July 2002

Extremely strong observational evidence has recently been
found for the presence of black holes orbiting a few relatively normal
stars in our Milky Way Galaxy and also at the centers of some galaxies.
The former generally have masses of 4–16 times the mass of the sun,
whereas the latter are “supermassive black holes” with millions
to billions of solar masses. The evidence for a supermassive black hole
in the center of our galaxy is especially strong.
Continuing with Perm', Turning to Syktyvkar, or Standing on One's Own? The Debate about the Status of the Komi-Permiak Autonomous Okrug
Authors: Lallukka Seppo , Nikitina Liudmila
Published: July 2002

On 26 February 1925, the Soviet government, or the Presidium of the Central Executive Committee of the USSR, passed a resolution that, in effect, ensured the continuation of the separate development of the southern and the northern Komi, that is, the Komi-Permiaks and the Komi-Zyrians. In more detail, the Presidium decided,

(1) Considering the great territorial distance of the Permiak region from the Komi area, and owing to the lack of mutual economic ties between these two territories, to refuse the request of the Komi autonomous area and representatives of the Permiak population for inclusion of the Permiak region in the Komi area, thus keeping the Permiak region within the Urals province. (2) To consider it expedient to make the Permiak region into a special national okrug [that is, national district] with special concise staff and to subordinate the okrug directly to the Executive Committee of the Urals province.
Engaging with history after Macpherson
Authors: Grosvenor Ian , Myers Kevin
Published: July 2002

The Race Relations Amendment Act (2000) identifies a key role for education, and more specifically history, in promoting ‘race equality’ in Britain. In this article Ian Grosvenor and Kevin Myers consider the extent of young people's current engagement with the history of ‘diversity, change and immigration’ which underpins the commitment to ‘race equality’. Finding that in many of Britain's schools and universities a singular and exclusionary version of history continues to dominate the curriculum, they go on to consider the reasons for the neglect of multiculturalism. The authors identify the development of an aggressive national identity that depends on the past for its legitimacy and argue that this sense of the past is an important obstacle to future progress.
Communication deficits: assessment of subjects with frontal lobe damage in an interview setting
Authors: Bernicot Josie , Dardier Virginie
Published: July 2002

This paper is about communication deficits in an interview setting among adolescents with frontal lobe damage. One of the predominant characteristics of these patients is difficulty taking the context into account. Pragmatic theories, which attempt to clarify the link between the formal structure of language and the extra‐linguistic context (such as the interlocutor's characteristics or strategies), may help provide insight into the difficulties of these patients. An interview setting, viewed here as a communication situation, is governed by an interaction format based on specific cooperative principles. In this study, the results of subjects with frontal lobe damage (in the role of interviewee) were first compared with those of normal subjects in an interview situation. Three pragmatic indexes were considered: the number of utterances per speaking turn (speech quantity), amount of digression (keeping to the topic or predefined subject of conversation shared by the interlocutors) and prevalence of withinsubject contingency speaking turns without an intervening remark by the interviewer (topic development). Secondly, we attempted to determine whether the patients’ discourse was dependent upon the interviewer's conversational strategy (structured, non‐structured, or alternating). The results clearly point out the extent of the difficulty frontal lobe patients have conforming to the rules of the interview situation, whether regarding the amount of speech they produce or their ability to keep within and/or development of the topic of conversation. The data also indicated that the patients’ linguistic productions varied with the interviewer's strategy. The structured strategy did not always give rise to the best performance: while the unstructured and alternating strategies allowed patients to produce more utterances per speaking turn, the alternating strategy enabled better development of the interview topic. These results suggest that such variations could be put to fruitful use in remedial techniques.
Development of Cd8α/α and Cd8α/β T Cells in Major Histocompatibility Complex Class I–Deficient Mice
Authors: Das Gobardhan , Janeway Charles A.
Published: July 2002

Peripheral CD8+ T cells mainly use CD8α/β, and their development is mainly dependent on the major histocompatibility complex (MHC) class I proteins Kb and Db in H-2b mice. In this report, we have shown that the development of CD8α/β TCR-α/β cells in lymphoid organs as well as in intestinal intraepithelial lymphocytes (iIELs) is dependent on the MHC class I Kb and Db proteins. In contrast, TCR-α/β CD8α/α cells are found mainly in iIELs, and their numbers are unaffected in KbDb double knockout mice. Most of the TCR-γ/δ cells in the iIELs also bear CD8α/α, and they are also unaffected in KbDb −/− mice. In β2-microglobulin (β2m)-deficient mice, all of the TCR-α/β CD8α/α and CD8α/β T cells disappear, but TCR-γ/δ cells are unaffected by the absence of β2m.
A Broad Spectrum Secreted Chemokine Binding Protein Encoded by a Herpesvirus
Authors: Parry Christopher M. , Simas J. Pedro , Smith Vincent P. , Stewart C. Andrew , Minson Anthony C. , Efstathiou Stacey , Alcami Antonio
Published: July 2002

Chemokines are a family of small proteins that interact with seven-transmembrane domain receptors and modulate the migration of immune cells into sites of inflammation and infection. The murine gammaherpesvirus 68 M3 gene encodes a secreted 44-kD protein with no sequence similarity to known chemokine receptors. We show that M3 binds a broad range of chemokines, including CC, CXC, C, and CX3C chemokines, but does not bind human B cell–specific nor mouse neutrophil–specific CXC chemokines. This herpesvirus chemokine binding protein (hvCKBP) blocks the interaction of chemokines with high-affinity cellular receptors and inhibits chemokine-induced elevation of intracellular calcium levels. hvCKBP is the first soluble chemokine receptor identified in herpesviruses; it represents a novel protein structure with the ability to bind all subfamilies of chemokines in solution and has potential therapeutic applications.
Cations Affect the Rate of Gating Charge Recovery in Wild-type and W434F Shaker Channels through a Variety of Mechanisms
Authors: Varga Zoltan , Rayner Martin D. , Starkus John G.
Published: July 2002

In this study we examine the effects of ionic conditions on the gating charge movement in the fast inactivation–removed wild-type Shaker channel and its W434F mutant. Our results show that various ionic conditions influence the rate at which gating charge returns during repolarization following a depolarizing pulse. These effects are realized through different mechanisms, which include the regulation of channel closing by occupying the cavity, the modulation of transitions into inactivated states, and effects on transitions between closed states via a direct interaction with the channel's gating charges. In generating these effects the cations act from the different binding sites within the pore. Ionic conditions, in which conducting wild-type channels close at different rates, do not significantly affect the rate of charge recovery upon repolarization. In these conditions, channel closing is fast enough not to be rate-limiting in the charge recovery process. In the permanently P-inactivated mutant channel, however, channel closing becomes the rate-limiting step, presumably due to weakened ion–ion interactions inside the pore and a slower intrinsic rate of gate closure. Thus, variations in closing rate induced by different ions are reflected as variations in the rate of charge recovery. In 115 mM internal Tris+ and external K+, Cs+, or Rb+, low inward permeation of these ions can be observed through the mutant channel. In these instances, channel closing becomes slower than in Tris+O//Tris+I solutions showing resemblance to the wild-type channel, where higher inward ionic fluxes also retard channel closing. Our data indicate that cations regulate the transition into the inactivated states from the external lock-in site and possibly the deep site. The direct action of barium on charge movement is probably exerted from the deep site, but this effect is not very significant for monovalent cations.
Spherical representations and mixed symmetric spaces
Authors: Krötz Bernhard , Neeb Karl-Hermann , Ólafsson Gestur
Published: July 2002

Let

G

/

H

G/H

be a symmetric space admitting a

G
G

-invariant hyperbolic cone field. For each such cone field we construct a local tube domain

Ξ
\Xi

containing

G

/

H

G/H

as a boundary component. The domain

Ξ
\Xi

is an orbit of an Ol’shanskii type semi group

Γ
\Gamma

. We describe the structure of the group

G
G

and the domain

Ξ
\Xi

. Furthermore we explore the correspondence between

Γ
\Gamma

-modules of holomorphic sections of line bundles over

Ξ
\Xi

and spherical highest weight modules.
Unbounded components in parameter space of rational maps
Authors: Makienko Peter
Published: July 2002

Using pinching deformations of Riemann surfaces, we give several sufficient criteria for the space of quasiconformal deformations of rational map

R
R

of degree

d
d

to have non-compact closure in the space

R
a

t

d

Rat_{d}

of rational maps of degree

d
d

modulo conjugation by Möbius transformations.
A distributed environment for physical map construction.
Authors: Grigoriev A , Levin A , Lehrach H
Published: July 2002

MOTIVATION: With the main focus of the Human Genome Project shifting to sequencing, bioinformatics support for constructing large-scale genomic maps of other organisms is still required. We attempt to provide for this with our work, aimed at the delivery of robust and user-friendly contig-building software on the WWW. RESULTS: We present a prototype distributed analytical environment for molecular biologists working in the area of genomic mapping. It consists of the WWW server for constructing contigs from users' data with a hypertext output connected to Java-based map visualization software. AVAILABILITY: Freely available on http://www.mpimg-berlin-dahlem.mpg. de/ approximately andy/server/ CONTACT: andy@rag3.rz-berlin.mpg.de
Myosin light‐chain kinase regulates endothelial calcium entry and endothelium‐dependent vasodilation
Authors: Watanabe Hiroshi , Tran Quang‐Kim , Takeuchi Kazuhiko , Fukao Mitsuhiro , Liu Ming Y. , Kanno Morio , Hayashi Toshio , Iguchi Akihisa , Seto Minoru , Ohashi Kyoichi
Published: July 2002

Activation of smooth muscle myosin light‐chain kinase (MLCK) causes contraction. Here we have proven that MLCK controls Ca2+ entry (CE) in endothelial cells (ECs): MLCK antisense oligonucleotides strongly prevented bradykinin (BK)‐ and thapsigargin (TG)‐induced endothelial Ca2+ response, while MLCK sense did not. We also show that the relevant mechanism is not phosphorylation of myosin light‐chain (MLC): MLC phosphorylation by BK required CE, but MLC phosphorylation caused by the phosphatase inhibitor calyculin A did not trigger Ca2+ response. Most important, we provide for the first time strong evidence that, in contrast to its role in smooth muscle cells, activation of MLCK in ECs stimulates the production of important endothelium‐derived vascular relaxing factors: MLCK antisense and MLCK inhibitors abolished BK‐ and TG‐induced nitric oxide production, and MLCK inhibitors substantially inhibited acetylcholine‐stimulated hyperpolarization of smooth muscle cell membrane in rat mesenteric artery. These results indicate that MLCK controls endothelial CE, but not through MLC phosphorylation, and unveils a hitherto unknown physiological function of the enzyme: vasodilation through its action in endothelial cells. The study discovers a counter‐balancing role of MLCK in the regulation of vascular tone.
New perspectives on the evolution of protochordate sensory and locomotory systems, and the origin of brains and heads
Authors: Lacalli Thurston C.
Published: July 2002

Cladistic analyses generally place tunicates close to the base of the chordate lineage, consistent with the assumption that the tunicate tail is primitively simple, not secondarily reduced from a segmented trunk. Cephalochordates (i.e. amphioxus) are segmented and resemble vertebrates in having two distinct locomotory modes, slow for distance swimming and fast for escape, that depend on separate sets of motor neurons and muscle cells. The sense organs of both amphioxus and tunicate larvae serve essentially as navigational aids and, despite some uncertainty as to homologies, current molecular and ultrastructural data imply a close relationship between them. There are far fewer signs of modification and reduction in the amphioxus central nervous system (CNS), however, so it is arguably the closer to the ancestral condition. Similarities between amphioxus and tunicate sense organs are then most easily explained if distance swimming evolved before and escape behaviour after the two lineages diverged, leaving tunicates to adopt more passive means of avoiding predation. Neither group has the kind of sense organs or sensory integration centres an organism would need to monitor predators, yet mobile predators with eyes were probably important in the early Palaeozoic. For a predator, improvements in vision and locomotion are mutually reinforcing. Both features probably evolved rapidly and together, in an ‘arms race’ of eyes, brains and segments that left protochordates behind, and ultimately produced the vertebrate head.
Histidine pKa shifts and changes of tautomeric states induced by the binding of gallium‐protoporphyrin IX in the hemophore HasASM
Authors: Wolff Nicolas , Deniau Clarisse , Létoffé Sylvie , Simenel Catherine , Kumar Veena , Stojiljkovic Igor , Wandersman Cécile , Delepierre Muriel , Lecroisey Anne
Published: July 2002

The HasASM hemophore, secreted by Serratia marcescens, binds free or hemoprotein bound heme with high affinity and delivers it to a specific outer membrane receptor, HasR. In HasASM, heme is held by two loops and coordinated to iron by two residues, His 32 and Tyr 75. A third residue His 83 was shown recently to play a crucial role in heme ligation. To address the mechanistic issues of the heme capture and release processes, the histidine protonation states were studied in both apo‐ and holo‐forms of HasASM in solution. Holo‐HasASM was formed with gallium‐protoporphyrin IX (GaPPIX), giving rise to a diamagnetic protein. By use of heteronuclear correlation NMR spectroscopy, the imidazole side‐chain 15N and 1H resonances of the six HasASM histidines were assigned and their pKa values and predominant tautomeric states according to pH were determined. We show that protonation states of the heme pocket histidines can modulate the nucleophilic character of the two axial ligands and, consequently, control the heme binding. In particular, the essential role of the His 83 is emphasized according to its direct interaction with Tyr 75.
Basic physics of xylophone and marimba bars
Authors: Suits B. H.
Published: July 2002

The frequency-dependent wave velocity and nonsinusoidal spatial dependence found for transverse waves in finite vibrating bars stands in stark contrast to the solutions to the one-dimensional wave equation, for example for the idealized vibrating string. The difference is particularly important when the resulting vibrations are used to produce music. Here, the appropriate approximate equations for transverse vibrations on a uniform bar are developed and compared to measurements using wooden bars. The results are extended using a simple finite element model to provide a means to predict normal mode behavior in nonuniform wooden bars such as those used for xylophones, marimbas, and related musical instruments.
Acoustic optic hybrid (AOH) sensor
Authors: Matthews Anthony D. , Arrieta Lisa L.
Published: July 2002

The ability of laser vibrometers to receive and process acoustic echoes from the water surface above a submerged target is established and evaluated. Sonar echoes from a submerged target are collected from the water surface by a laser vibrometer. Feasibility of this approach to sensing underwater sound is demonstrated. If the acoustic excitation at an otherwise undisturbed water surface is 195 to 168 dB re: 1 μPa, signal-to-noise ratio (SNR), at the vibrometer output, is shown to range from about 46 to 6 dB. Capillary waves and gravity waves at the water surface are expected and shown to have some destructive effect on the process of echo retrieval. A series of experiments to quantify the surface wave effects is described. The wave experiment results are reported. A successful attempt to acquire echoes from a submerged target over a grid of points for further processing into a three-dimensional image is made and described. The data acquisition and beamforming techniques constitute a three-dimensional, acoustic optic, synthetic aperture sonar (SAS). Beamformed images are included. For an aircraft towing acoustic sensors through the water with a mechanical link, this technique holds the promise of increased safety and improved fuel efficiency.
Sound source location by difference of phase, on a hydrophone array with small dimensions
Authors: Brensing Karsten , Linke Katrin , Todt Dietmar
Published: July 2002

A method for localizing calling animals was tested at the Research and Education Center Dolphins Plus in Key Largo, FL, under realistic field conditions. Experiments were performed with bottlenose dolphins (Tursiops truncatus) using a special hydrophone arrangement. There were two groups of hydrophones, and the two hydrophones in each group were 15 cm apart. The groups were separated by a distance of 15 m. Acoustic signals from the animals were recorded by use of a digital data acquisition system with a sampling rate of 1 MHz. All data were processed off-line. The time delay was measured by the phase difference in a single wavelength on whistles and clicks. The bearing of the signals was calculated with help of the time delay. This method has high precision and provides the possibility for analyzing overlapped signals.
Three-dimensional vibration analysis of a homogeneous transversely isotropic thermoelastic cylindrical panel
Authors: Sharma J. N.
Published: July 2002

In this paper, based on three-dimensional thermoelasticity, an exact analysis of the free vibrations of a simply supported, homogeneous, transversely isotropic, cylindrical panel is presented. Three displacement potential functions are introduced so that the equations of motion and heat conduction are uncoupled and simplified. It is noticed that a purely transverse mode is independent of temperature change and the rest of the motion. The equations for free vibration problems are further reduced to four second-order ordinary differential equations, after expanding the potential and temperature functions with an orthogonal series. A modified Bessel function solution with complex arguments is directly used for complex eigenvalues. To clarify the developed method and compare the results to the existing ones, numerical examples are presented.
Direct measurement of ultrasonic velocity of thin elastic layers
Authors: Wan Mingxi , Jiang Bei , Cao Wenwu
Published: July 2002

This letter reports a simple new technique for the ultrasonic velocity measurement on thin elastic layers of fractional wavelength thickness using broadband transducers. An external trigger to the oscilloscope with continuously variable frequency and an intensity enhancing strobe signal allow direct measurement of the wavefront time shift down to 13 ns. The technique makes it possible to measure the sound velocity of thin layers with the thickness down to 10−2λ. Using a pair of 2.25-MHz transducers, we have accurately measured the sound velocity of a 26-μm-thick aluminum foil.
Spectra and fourth-order cumulant spectra of broadband beamformed data
Authors: Dwyer Roger F.
Published: July 2002

Sensor arrays play a major role in underwater acoustic applications. They allow propagating signals to be spatially separated after beamforming giving direction of arrival information. They are usually designed by sensor spacing selection for a particular frequency but used over a band of frequencies. For wideband applications, arrays designed with nonuniform sensor spacing have been utilized. But many of the existing acoustic arrays are designed with uniform sensor spacing. When these arrays are used beyond their design frequency spatial resolution is reduced at low frequencies and grating lobes appear at higher frequencies based on the second-order spectrum. To define these effects a theorem and a corollary are stated and proven under general conditions. In contrast, the fourth-order cumulant spectrum provides more flexibility in choosing the frequency response at the output of a beamformer so deliterious effects of wide frequency bandwidths can be reduced. To define these improvements another theorem and corollary are stated and proven for the fourth-order cumulant spectrum. To demonstrate these theoretical results returns from an active sonar system have been simulated. The transmitted waveform is a linear frequency modulated signal and the echo is returned from a spherical target that is either stationary or in motion. The returned signal is beamformed using a one-dimensional line array of uniformly spaced sensors designed for a frequency of 4160 Hz. But the transmitted waveform has a bandwidth from 1 Hz to 8 kHz. The results are given for the matched and mismatched filtered beamformer outputs of a ten-element line array in the frequency and range domains. These results are compared with the fourth-order cumulant spectrum of the beamformer output and its range domain representation.
The effects of surfactant additives on the acoustic and light emissions from a single stable sonoluminescing bubble
Authors: Stottlemyer Thomas R. , Apfel Robert E.
Published: July 2002

The localized concentration of energy during a single bubble collapse is manifested in two forms, which are the emission of an acoustic pulse, and the emission of a light pulse. Through precise control of experimental parameters, one can levitate a single bubble in a standing wave field and measure the magnitude of the acoustic and light pulses resulting from the violent collapse of the cavity. The information acquired from such measurements provides better understanding of the mechanisms that are responsible for the emissions, which may lead to the practical application of controlled bubble implosions. An experimental apparatus was developed to measure the acoustic and light emissions from a single, stable sonoluminescing bubble. Two surfactant additives were studied to determine the effects on the bubble emissions. Triton X-100, which has previously been shown to provide free interfacial motion, reduced the magnitude of both the acoustic and light pulses from the bubble. The protein bovine serum albumin (BSA) which has been shown to hinder interfacial motion, allowed the bubble to be driven to higher acoustic pressures, and resulted in an increase in the magnitude of the light pulses from the bubble. Images of the sonoluminescing bubble indicate that the collapse remains spherical in the cases presented, and that bubble translation can be correlated with weak acoustic and light emissions.
Effects of local speaking rate context on the perception of voice-onset time in initial stop consonants
Authors: Utman Jennifer Aydelott
Published: July 2002

This study explored the prediction that local speaking rate context affects the perception of voice-onset time (VOT) in initial stop consonants not only for ambiguous stimuli at the category boundary, but also for good exemplars from the category center [Volaitis and Miller, J. Acoust. Soc. Am. 92, 723–735 (1992)]. Naturally produced exemplars of the voiceless phonetic category were presented in the context of syllables produced at fast or slow speaking rates in a series of perceptual tasks, including phonetic discrimination, identification, and goodness rating. The results from all three tasks revealed no effects of speaking rate context on the perception of VOT in initial stop consonants. Rather, it appears that listeners perceive longer VOTs as better exemplars of the voiceless phonetic category, irrespective of the rate context. Further, an additional condition, in which the instructions and familiarization tasks presented prior to the administration of the perceptual tests were similar to those used by Volaitis and Miller [J. Acoust. Soc. Am. 92, 723–735 (1992)], revealed that the previous results may have been influenced by the experimental design.
The oscillations of a gas bubble in a tube
Authors: Geng X. , Yuan H. , Og̃uz H. , Prosperetti Andrea
Published: July 2002

In principle, gas bubbles can be effective actuators in small liquid handling devices such as those that the new silicon manufacturing technologies make possible. Their attractiveness for this application stems from an inherently high frequency of vibration, the possibility to power the bubble remotely by ultrasound, and the absence of mechanical moving parts. Among the most fundamental pieces of information that are required to evaluate this application are the natural frequency and damping rate of the volume pulsations of a bubble in the constrained environment of a tube. After a brief review of the pertinent theoretical aspects recently developed by the authors, the paper presents the results of an experiment in which an air bubble in a 1-mm-diam partially filled tube is driven by a thin rod mounted on a loudspeaker. The amplitude of pulsation of the bubble is measured as a function of frequency by phase locking the exposure of a CCD camera with the acoustic wave. A general agreement between theory and experiment is found, although the measured damping rate exceeds the theoretical value. [Work supported by the Air Force Office of Scientific Research.]
Effects of syllable-initial voicing and speaking rate on the temporal characteristics of monosyllabic words
Authors: Allen J. Sean , Miller Joanne L.
Published: July 2002

Two speech production experiments tested the validity of the traditional method of creating voice-onset-time (VOT) continua for perceptual studies in which the systematic increase in VOT across the continuum is accompanied by a concomitant decrease in the duration of the following vowel. In experiment 1, segmental durations were measured for matched monosyllabic words beginning with either a voiced stop (e.g., big, duck, gap) or a voiceless stop (e.g., pig, tuck, cap). Results from four talkers showed that the change from voiced to voiceless stop produced not only an increase in VOT, but also a decrease in vowel duration. However, the decrease in vowel duration was consistently less than the increase in VOT. In experiment 2, results from four new talkers replicated these findings at two rates of speech, as well as highlighted the contrasting temporal effects on vowel duration of an increase in VOT due to a change in syllable-initial voicing versus a change in speaking rate. It was concluded that the traditional method of creating VOT continua for perceptual experiments, although not perfect, approximates natural speech by capturing the basic trade-off between VOT and vowel duration in syllable-initial voiced versus voiceless stop consonants.
Falling Sphere Viscometry. I. Wall and Inertial Corrections to Stokes' Law in Long Tubes
Authors: Sutterby J. Lloyd
Published: July 2002

The classical expression for determining viscosity from sphere fall velocity is Stokes' law. Stokes' law applies in the absence of wall and inertial effects. In the usual experimental apparatus there are wall effects and there may be inertial effects. The objective of this paper is to establish a correlation of wall and inertial corrections to Stokes' law in the range appropriate for falling sphere viscometry, and to present this correlation in a manner convenient for application. The desired correlation is presented in Table II and Figure 5 of the text. The new correlation should be useful in determining the viscosity of Newtonian fluids and in determining the zero shear rate viscosity of polymer solutions.
The Use of Hybrid Methods for the Numerical Determination of the Relaxation or Retardation Spectra
Authors: Stanislav J. , Hlavác̆ek B.
Published: July 2002

The advantages of using the hybrid methods for calculation of the relaxation spectrum are demonstrated. A starting point for the numerical method is one of the higher approximations of relaxation spectrum due to Schwarzl and Staverman, Fujita, Ferry and Ninomiya, and Tschoegl. The corresponding kernel functions are generally “well posed”. Further improvement in the determination of relaxation spectrum may be achieved when a suitable numerical method is used. A sample calculation for a wide spectrum and Rouse distribution of relaxation times is presented.
Ethylene Oxide
Authors: Dever John P. , Nunley Mark A. , Rader Jeremy R. , Proulx Grant
Published: March 2022

Ethylene oxide (EO) [75‐21‐8] was first prepared in 1859 by Wurtz from 2‐chloroethanol (ethylene chlorohydrin) and aqueous potassium hydroxide. Wurtz later attempted to produce EO by direct oxidation but did not succeed. Many other researchers were also unsuccessful. In 1931, Lefort achieved direct oxidation of ethylene to EO using a silver catalyst. Although early manufacture of EO was accomplished by the chlorohydrin process, the direct oxidation process has been used almost exclusively since 1940. The primary use of EO is in the manufacture of derivatives such as ethylene glycol, surfactants, and ethanolamines.
An Underwater Long‐Term Strong Adhesive Based on Boronic Esters with Enhanced Hydrolytic Stability
Authors: Zhao Zi‐Han , Zhao Pei‐Chen , Zhao Yue , Zuo Jing‐Lin , Li Cheng‐Hui
Published: March 2022

Boron‐based adhesives have attracted considerable attention in recent years due to their strong adhesive behavior and reversible capacities. However, limited by the humidity sensitivity and poor dynamicity, it remains challenging for the boron‐based adhesive materials to realize strong and long‐term adhesion underwater. In this study, a novel boronic ester (BN‐6) with changeable ring strain induced by the heat‐responsive BN coordination bond is designed and synthesized. Due to the low strain of the six‐membered ring at ambient conditions and the high strain of the ten‐membered ring at elevated temperature, BN‐6 exhibits enhanced hydrolytic/thermal stabilities as well as dynamicity. The model dynamic crosslinking polymers containing BN‐6 linkages present significantly improved water‐resistance and recyclability. Specifically, based on the hydrolytically stable whilst kinetically active boronic ester linkage, a strong and recyclable adhesive material is successfully prepared. Long‐term adhesion performance under water and harsh conditions is realized on different substrates, with the maximum adhesion strength of 4.21 MPa. The report provides a novel chemical strategy for designing stable and dynamic boronic ester linkages and the synthesized adhesive has pioneered in the field of long‐term underwater application of boron‐based adhesives.
Atomically Sharp Lateral Superlattice Heterojunctions Built‐In Nitrogen‐Doped Nanoporous Graphene
Authors: Tenorio Maria , Moreno Cesar , Febrer Pol , Castro‐Esteban Jesús , Ordejón Pablo , Peña Diego , Pruneda Miguel , Mugarza Aitor
Published: March 2022

Nanometer scale lateral heterostructures with atomically sharp band discontinuities can be conceived as the 2D analogues of vertical Van der Waals heterostructures, where pristine properties of each component coexist with interfacial phenomena that result in a variety of exotic quantum phenomena. However, despite considerable advances in the fabrication of lateral heterostructures, controlling their covalent interfaces and band discontinuities with atomic precision, scaling down components and producing periodic, lattice‐coherent superlattices still represent major challenges. Here, a synthetic strategy to fabricate nanometer scale, coherent lateral superlattice heterojunctions with atomically sharp band discontinuity is reported. By merging interdigitated arrays of different types of graphene nanoribbons by means of a novel on‐surface reaction, superlattices of 1D, and chemically heterogeneous nanoporous junctions are obtained. The latter host subnanometer quantum dipoles and tunneling in‐gap states, altogether expected to promote interfacial phenomena such as interribbon excitons or selective photocatalysis.
Wet‐Chemistry: A Useful Tool for Deriving Metal–Organic Frameworks toward Supercapacitors and Secondary Batteries
Authors: Zhao Xi , Zheng Yihe , Dai Henghan , Yang Jia , Chen Qiang , Zhou Jinyuan , Sun Gengzhi
Published: March 2022

Metal–organic frameworks (MOFs) possess the advantages of tailorable porosity, adjustable composition, and tunable topologies and are considered promising precursors and self‐templates for the synthesis of complex nanostructures as advanced electrode materials for energy storage. Among various strategies, wet‐chemical method endows better control over topological evolution and compositional transformation of MOF crystals. Herein, the authors comprehensively review the recent achievements on wet‐chemical derivation of MOF via etching, ion‐exchange, hydrolysis, and chemical transformation, underscore the corresponding mechanisms, and highlight their important applications in supercapacitors and secondary batteries.
Thermoconformable, Flexible Lithium‐Ion Batteries
Authors: Boaretto Nicola , Dávila Beatriz , Sevilla Sonia , García Guzmán , Mikhalchan Anastasiia , Rana Moumita , Yusuf Abdulmalik , Ubierna Martinez Lucio , Castillo García Marta , Palma Jesús , Wang De‐Yi , Marcilla Rebeca , José Vilatela Juan
Published: March 2022

This work introduces a scalable method for fabrication of flexible, thermoconformable lithium‐ion batteries, suitable for the interior of vehicles. Electrodes with a composite structure are fabricated by combining conventional granular slurries with a porous carbon nanotube fabric current collector and a solid gel polymer electrolyte. The composite structure reduces polarization at high current densities, for example, with 50% and 17% higher charge capacity at 1C in LTO/Li half cells than control samples and commercial electrodes, respectively. Introducing a gel‐polymer electrolyte increases cell durability, safety, and thermal stability. Cyclability test at of 1C shows a capacity retention as high as 91% after almost 400 cycles (average capacity fade of 0.025% cycle−1). Full cells operate from 0 to 60 °C without any additives. Cells stored for 30 min up to 90 °C suffer minor capacity degradation. The possibility to withstand high temperatures and significant flexural deformation enable subjecting these pouch cells to thermoconformable processes. A roof panel with four 25 cm2 pouch cells is demonstrated. Flammability test shows that the carbon nanotube fibers (CNTF)‐LFP/CNTF‐LTO cells have a 50% lower peak of heat release rate and a much smaller total heat released than control cells with metallic current collector and liquid electrolyte.
Six‐arm Stellat Dendritic‐PbS Flexible Infrared Photodetector for Intelligent Healthcare Monitoring
Authors: Zhang Tuo , Ling Cuicui , Wang Xiaomeng , Feng Bingxin , Cao Min , Xue Xin , Xue Qingzhong , Zhang Jianqiang , Zhu Lei , Wang Chuanke , Lu Haipeng , Liu Wenpeng
Published: March 2022

The flexible photodetector plays an important role in improving human medical health status. However, the narrow spectral detection range, poor stress stability, and non‐degradation of traditional flexible photodetectors greatly hinder the further development of wearable medical devices. In this paper, a novel flexible infrared photodetector is proposed for intelligent healthcare monitoring using high purity lead sulfide (PbS) nanoparticles on paper‐based flexible substrate synthesized by hydrothermal method and physical friction. The excellent performance of the detector is attributed to the 1.01 eV band gap and six‐arm stellate dendritic structure of PdS, a good combination between PbS and paper substrate via physical friction. As a result, our photodetector demonstrates wide‐spectrum detection capabilities from 365 to 1550 nm. The photodetector at 980 nm (50.4 μW cm−2) shows responsivity of 6.45 mA W−1, detectivity of 6.4 × 1010 Jones, response recovery time of 0.36 s/0.41 s, with good mechanical stability. By comparison, our detector has a wider detection range, better weak signal detection performance, and shorter response time than the performance of the former paper‐based detector. Furthermore, the paper‐based PbS photodetector as a dual‐wavelength photoplethysmography sensor is applied to analyze the oxygen saturation and develop an intelligent bandage to monitor wound healing. This paper‐based PbS photodetector has tremendous potential in the field of wearable medical devices and intelligent medical applications are expected.
In Situ Temperature Dependent Optical Characterization and Modeling of Dealloyed Thin‐Film Nanoporous Gold Absorbers
Authors: Ramesh Rajagopalan , Niauzorau Stanislau , Sampath Venkata Krishnan , Wang Liping , Azeredo Bruno P.
Published: March 2022

Nanostructured noble metals such as gold exhibit unique size‐dependent plasmonic and optical properties which is an enabling factor for designing nanophotonic devices. However, for its deployment in high temperature applications such as solar thermal energy harvesting and optothermal conversion, it requires understanding of its temperature dependent optical properties. This paper investigates the in situ specular reflectance of nanoporous gold (NPG) thin films in the wavelength range between 400 and 1000 nm at temperatures ranging from 25 to 500 °C via a home‐built fiber‐based optical spectrometer. During heating, the NPG's ligaments coalesce from an initial size of 39 ± 12 nm to a final size of up to 299 ± 114 nm, and its ligament scales with temperature closely matching an Arrhenius dependence. The surface roughness of NPG is empirically correlated to ligament size and temperature to allow for the theoretical prediction of the relative specular reflectance using scattering coefficients and effective medium theory which closely matches the experimental results. These results represent a step forward in using in situ optical spectroscopic methods to monitor the ligament size evolution of NPG thin‐films and to understand its stability and optical properties for applications at elevated temperatures.
Electromagnetic Diffusion and Encryption Holography Integration Based on Reflection–Transmission Reconfigurable Digital Coding Metasurface
Authors: Wu Liang Wei , Xiao Qiang , Gou Yue , Wu Rui Yuan , Xu Peng , Qing Ye Ming , Wang Zheng Xing , Bao Lei , Ma Hui Feng , Cui Tie Jun
Published: March 2022

The integration of different functionalities into a real‐time reconfigurable metasurface can give it more powerful ability in manipulation of electromagnetic (EM) waves. Here, a reflection–transmission (R‐T) reconfigurable digital coding metasurface, which can be flexibly switched between the reflection and transmission working states with the completely different functions, is proposed and demonstrated. As a proof of concept, an R‐T reconfigurable metasurface with integrated functions of EM diffusion in reflection state and encryption holography in transmission state is designed and demonstrated. The results have been validated by both numerical simulations and experimental measurements, showing that the proposed R‐T reconfigurable metasurface can be real‐timely controlled to work in reflection state or transmission state by adjusting bias voltage, in which the incident EM waves are totally reflected and randomly diffused to achieve low radar cross section (RCS) in reflection state and efficiently transmitted to realize encrypted holographic images in transmission state.
Ultra‐Efficient GAGG:Cr3+Ceramic Phosphor‐Converted Laser Diode: A Promising High‐Power Compact Near‐Infrared Light Source Enabling Clear Imaging
Authors: Jiang Hangjie , Chen Liyan , Zheng Guojun , Luo Zhaohua , Wu Xianhui , Liu Zehua , Li Ruiyang , Liu Yongfu , Sun Peng , Jiang Jun
Published: March 2022

Near‐infrared (NIR) light is widely used in fields such as organic components detection and biological imaging, due to its strong tissue penetration and non‐destructive characteristics. To improve the detection sensitivity and spatial resolution of bioimaging, it is important to obtain a new NIR light source with good thermal stability, high efficiency, and ultra‐high optical output power, which currently remains a great challenge. In view of this, a Gd3Al2Ga3O12:Cr3+(GAGG:Cr3+) NIR ceramic phosphor is proposed in this study. By optimizing the preparation process of GAGG:Cr3+ceramic phosphor and the concentration of Cr3+ions, high external quantum efficiency (EQE = 70.1%) and excellent thermal stability (96.8%@150 °C) are achieved. After coupling the GAGG:Cr3+ceramic phosphor with a blue light‐emitting diode (LED), the electro‐optical conversion efficiency of the NIR ceramic phosphor converted LED (NIR‐cpc‐LED) reaches 31%@20 mA, which is higher than the previously reported values. Moreover, when coupled with a blue laser diode (LD), the optical output power of the NIR‐cpc‐LD reaches as high as 1652.6 mW@5.5 W. Therefore, GAGG:Cr3+NIR‐cpc‐LD not only shows a great prospect in practical applications, but also provides a new solution for high‐power compact NIR light sources.
High‐Efficiency Air‐Processed Si‐Based Perovskite Light‐Emitting Devices via PMMA‐TBAPF6 Co‐Doping
Authors: Xu Xiaoxiao , Zhu Ting , Xiao Ke , Zhu Yu , Chen Jiaming , Li Dongke , Xu Ling , Xu Jun , Chen Kunji
Published: March 2022

The preparation of high‐efficiency perovskite light‐emitting devices (PeLEDs) in the air‐ambient has always been a challenge. Herein, the authors propose a Si‐based near‐infrared air‐processed PeLED through the anti‐solvent engineering. Two materials, poly(methyl methacrylate) (PMMA) and tetrabutylammonium hexafluorophosphate (TBAPF6) are co‐doped into the anti‐solvent, the former protects the perovskite from degradation in a high‐humidity atmosphere, and the latter passivates the defects on perovskite surface and increases the conductivity. Through the anti‐solvent engineering, the efficiency of PeLEDs has been significantly enhanced and obtains a maximum external quantum efficiency (EQE) of 10.4%, which is the highest among similar devices. This work shows that it is possible to prepare high‐efficiency near‐infrared PeLEDs in air‐ambient through a simple method.
Promoting Mechanistic Understanding of Lithium Deposition and Solid‐Electrolyte Interphase (SEI) Formation Using Advanced Characterization and Simulation Methods: Recent Progress, Limitations, and Future Perspectives
Authors: Xu Yaolin , Dong Kang , Jie Yulin , Adelhelm Philipp , Chen Yawei , Xu Liang , Yu Peiping , Kim Junghwa , Kochovski Zdravko , Yu Zhilong , Li Wanxia , LeBeau James , Shao‐Horn Yang , Cao Ruiguo , Jiao Shuhong , Cheng Tao , Manke Ingo , Lu Yan
Published: March 2022

In recent years, due to its great promise in boosting the energy density of lithium batteries for future energy storage, research on the Li metal anode, as an alternative to the graphite anode in Li‐ion batteries, has gained significant momentum. However, the practical use of Li metal anodes has been plagued by unstable Li (re)deposition and poor cyclability. Although tremendous efforts have been devoted to the stabilization of Li metal anodes, the mechanisms of electrochemical (re‐)deposition/dissolution of Li and solid‐electrolyte‐interphase (SEI) formation remain elusive. This article highlights the recent mechanistic understandings and observations of Li deposition/dissolution and SEI formation achieved from advanced characterization techniques and simulation methods, and discusses major limitations and open questions in these processes. In particular, the authors provide their perspectives on advanced and emerging/potential methods for obtaining new insights into these questions. In addition, they give an outlook into cutting‐edge interdisciplinary research topics for Li metal anodes. It pushes beyond the current knowledge and is expected to accelerate development toward a more in‐depth and comprehensive understanding, in order to guide future research on Li metal anodes toward practical application.
Synthesis of Chiral Endocyclic Allenes by Palladium‐Catalyzed Asymmetric Annulation Followed by Cope Rearrangement
Authors: Shi Bin , Liu Jia‐Bin , Wang Ze‐Tian , Wang Liang , Lan Yu , Lu Liang‐Qiu , Xiao Wen‐Jing
Published: March 2022

Catalytic asymmetric synthesis of chiral endocyclic allenes remains a challenge in allene chemistry owing to unfavored tension and complex chirality. Here, we present a new relay strategy merging Pd‐catalyzed asymmetric [3+2] annulation with enyne‐Cope rearrangement, providing a facile route to chiral 9‐membered endocyclic allenes with high efficiency and enantioselectivity. Moreover, theoretical calculations and experimental studies were performed to illustrate the critical, but unusual Cope rearrangement that allows for the complete central‐to‐axial chirality transfer.
A Bacteria‐Responsive Porphyrin for Adaptable Photodynamic/Photothermal Therapy
Authors: Hu Hao , Wang Hua , Yang Yuchong , Xu Jiang‐Fei , Zhang Xi
Published: March 2022

We report a cationic porphyrin 5,10,15,20‐tetrakis‐(4‐N‐methylpyridyl)‐porphyrin (TMPyP) that can respond to specific bacteria, followed by adaptable photodynamic/photothermal therapy processes. TMPyP could be reduced to phlorin by facultative anaerobes with a strong reducing ability such as E. coli and S. typhimurium in hypoxic environments, possessing strong NIR absorption and remarkable photothermal conversion capacity, thus demonstrating excellent antimicrobial activity (>99 %) by photothermal therapy. While in an aerobic environment with aerobic bacteria, TMPyP functioned as a typical photosensitizer that killed bacteria effectively (>99.9 %) by photodynamic therapy. By forming a host–guest complex with cucurbit[7]uril, the biocompatibility of TMPyP significantly improved. This kind of bacteria‐responsive porphyrin shows specificity and adaptivity in antimicrobial treatment and holds potential in non‐invasive treatments of bacterial infections.
Reducing Energy Disorder for Efficient and Stable Sn−Pb Alloyed Perovskite Solar Cells.
Authors: Peng Cheng , Li Chongwen , Zhu Mingzhe , Zhang Chujun , Jiang Xiafei , Yin Hang , He Benlin , Li Haiyan , Li Ming , So Shu Kong , Zhou Zhongmin
Published: March 2022

Sn−Pb alloyed perovskites have drawn considerable attention because of their appropriate band gap for both single‐junction and multi‐junction tandem photovoltaics, but the easy‐formation of energy disorder still limits their practical applications. Here, we report that the combination of 1‐bromo‐4‐(methylsulfinyl) benzene (BBMS) and SnF2 greatly reduced the Urbach energy of perovskite films, and largely restrained the oxidation of Sn2+. With the help of density functional theory calculations, we clarified the interactions between BBMS and perovskite were responsible for the improvements. As a result, a high efficiency of >22 % was obtained for the Sn−Pb alloy‐based solar cells treated by BBMS and SnF2. More importantly, the BBMS‐treated devices demonstrated outstanding stability, retaining 98 % of its original efficiency after heating at 60 °C for 2660 h under N2.