bluuebunny/crossref_metadata_2025 huggingface dataset:
Pincher, a pinocytic chaperone for nerve growth factor/TrkA signaling endosomes
Authors: Shao Yufang , Akmentin Wendy , Toledo-Aral Juan Jose , Rosenbaum Julie , Valdez Gregorio , Cabot John B. , Hilbush Brian S. , Halegoua Simon
Published: July 2002

Acentral tenet of nerve growth factor (NGF) action that is poorly understood is its ability to mediate cytoplasmic signaling, through its receptor TrkA, that is initiated at the nerve terminal and conveyed to the soma. We identified an NGF-induced protein that we termed Pincher (pinocytic chaperone) that mediates endocytosis and trafficking of NGF and its receptor TrkA. In PC12 cells, overexpression of Pincher dramatically stimulated NGF-induced endocytosis of TrkA, unexpectedly at sites of clathrin-independent macropinocytosis within cell surface ruffles. Subsequently, a system of Pincher-containing tubules mediated the delivery of NGF/TrkA-containing vesicles to cytoplasmic accumulations. These vesicles selectively and persistently mediated TrkA-erk5 mitogen-activated protein kinase signaling. A dominant inhibitory mutant form of Pincher inhibited the NGF-induced endocytosis of TrkA, and selectively blocked TrkA-mediated cytoplasmic signaling of erk5, but not erk1/2, kinases. Our results indicate that Pincher mediates pinocytic endocytosis of functionally specialized NGF/TrkA endosomes with persistent signaling potential.
Subclass-Specific Nuclear Localization of a Novel Cd4 Silencer Binding Factor
Authors: Kim William W.S. , Siu Gerald
Published: July 2002

The control of CD4 expression is essential for proper T lymphocyte development. We have previously described a cis-acting silencer element required for repressing transcription of the CD4 gene. Here we report the cloning and characterization of a novel factor that binds to a critical functional site in the CD4 silencer. This factor, referred to as silencer-associated factor (SAF), is a member of the helix-turn-helix factor family and shares sequence similarity with the homeodomain class of transcriptional regulators. Introduction of a specific mutation into the SAF binding site in the CD4 silencer abrogates silencer activity in transgenic mice, supporting the hypothesis that SAF is important in mediating silencer function. Although SAF is expressed in all lymphocytes, immunofluorescence studies indicate that SAF is present primarily in the cytoplasm in T cells in which the endogenous silencer is nonfunctional, whereas it is present primarily in the nucleus in T cells in which the silencer is functional. We thus hypothesize that the subclass-specific subcellular compartmentalization of SAF plays an important role in mediating the specificity of function of the CD4 silencer during T cell development.
Link between Organ-specific Antigen Processing by 20S Proteasomes and CD8+ T Cell–mediated Autoimmunity
Authors: Kuckelkorn Ulrike , Ruppert Thomas , Strehl Britta , Jungblut Peter R. , Zimny-Arndt Ursula , Lamer Stephanie , Prinz Immo , Drung Ilse , Kloetzel Peter-M. , Kaufmann Stefan H.E. , Steinhoff Ulrich
Published: July 2002

Adoptive transfer of cross-reactive HSP60-specific CD8+ T cells into immunodeficient mice causes autoimmune intestinal pathology restricted to the small intestine. We wondered whether local immunopathology induced by CD8+ T cells can be explained by tissue-specific differences in proteasome-mediated processing of major histocompatibility complex class I T cell epitopes. Our experiments demonstrate that 20S proteasomes of different organs display a characteristic composition of α and β chain subunits and produce distinct peptide fragments with respect to both quality and quantity. Digests of HSP60 polypeptides by 20S proteasomes show most efficient generation of the pathology related CD8+ T cell epitope in the small intestine. Further, we demonstrate that the organ-specific potential to produce defined T cell epitopes reflects quantities that are relevant for cytotoxic T lymphocyte recognition. We propose tissue-specific antigen processing by 20S proteasomes as a potential mechanism to control organ-specific immune responses.
The Krein-Milman theorem in operator convexity
Authors: Webster Corran , Winkler Soren
Published: July 2002

We generalize the Krein-Milman theorem to the setting of matrix convex sets of Effros-Winkler, extending the work of Farenick-Morenz on compact C

∗

^*

-convex sets of complex matrices and the matrix state spaces of C

∗

^*

-algebras. An essential ingredient is to prove the non-commutative analogue of the fact that a compact convex set

K
K

may be thought of as the state space of the space of continuous affine functions on

K
K

.
Factorizing complex symmetric matrices with positive definite real and imaginary parts
Authors: Higham Nicholas
Published: July 2002

Complex symmetric matrices whose real and imaginary parts are positive definite are shown to have a growth factor bounded by 2 for LU factorization. This result adds to the classes of matrix for which it is known to be safe not to pivot in LU factorization. Block

L
D

L
T

\mathrm {LDL^T}

factorization with the pivoting strategy of Bunch and Kaufman is also considered, and it is shown that for such matrices only

1
×
1

1\times 1

pivots are used and the same growth factor bound of 2 holds, but that interchanges that destroy band structure may be made. The latter results hold whether the pivoting strategy uses the usual absolute value or the modification employed in LINPACK and LAPACK.
Model theory and diophantine geometry
Authors: Pillay Anand
Published: July 2002

I discuss some recent applications of model theory to diophantine-type problems in algebraic geometry. I give the required background, as well as a sketch of the proofs.
CHILDREN AND THE ENVIRONMENT: VALUING INDIRECT EFFECTS ON A CHILD'S LIFE CHANCES
Authors: Shogren Jason F.
Published: July 2002

Children can face disproportionately greater risk from environmental hazards because they are kids—smaller bodies, faster metabolisms, shorter attentions spans, less knowledge, and fewer resources. Environmental programs that reduce risks to children produce benefits to society that should be adequately represented so policy makers have more information to help them decide which policies are most worthwhile relative to their costs. The open question is just how exactly to value these reductions in risks to children, risks which can arise either from a direct effect on their health, or an indirect effect on their life chances because of illness in other family members or the degradation of the environment. This article focuses on valuing these indirect effects to a child's life chances. The question addressed here is whether standard benefits estimation adequately captures the indirect effects on healthy children. If policy makers presume caregivers make fully informed, rational choices when dealing with adverse family health, indirect effects are already accounted for in revealed and stated values: estimating indirect effects implies double counting of benefits. But if policy makers fear that caregivers face choice without complete information or experience, indirect effects might be understated. Then it becomes constructive to devote resources to explore the importance of these indirect effects.
SHORT‐RUN MONETARY POLICY AND THE MACROECONOMIC ENVIRONMENT
Authors: Pierce Thomas J. , Rebeck Ken
Published: July 2002

This study investigates factors influencing monetary policy decisions of the Federal Open Market Committee (FOMC) over the period 1960–1998. Competing perspectives regarding the process of monetary policy making exist, with some researchers contending the FOMC makes short‐run policy decisions based solely on “objective” macroeconomic considerations and others arguing that political and other nonmacroeconomic considerations significantly influence monetary policy voting. Empirical studies support both views in varying degrees. This article presents a model of FOMC decision making which posits that (1) the current/prospective macroeconomic environment at the time of FOMC meetings is the most important consideration of monetary policy makers, and (2) nonmacroeconomic variables receive little attention unless macroeconomic conditions are difficult for policy makers to assess. Probit results support the implications of the model.
Bequest Motives, Social Security, and Economic Growth
Authors: Zhang Junsen , Zhang Junxi
Published: July 2002

This article conducts a systematic analysis of four bequest motives in a simple model of endogenous growth. It analyzes how bequest motives affect fertility, savings, growth, and the effects of pay‐as‐you‐go Social Security. It is found that altruistic and exchange motives give equivalent outcomes if the discount factors are set the same. The outcome under the joy‐of‐giving motive may involve a higher bequest ratio, higher saving, and better growth rates than that under altruism. If bequests are accidental, the equilibrium values will depend on the probability of survival. Moreover, the results provide testable implications on bequest motives.
Understanding Investment Irreversibility in General Equilibrium
Authors: Faig Miquel
Published: July 2002

In general equilibrium, irreversibility affects both the wealth of consumers and the return on assets. As long as the inter‐temporal elasticity of substitution is realistically low, irreversibility not only prevents capital destruction, but it also induces capital creation. Furthermore, under certain conditions, irreversibility raises the risk premium by increasing the variability of consumption and market portfolio. These issues are dealt in a simple model of investment irreversibility with multiple types of capital. Its tractability allows for analytical results which explain the contrast between the consequences of irreversibility for individual markets and the consequences of irreversibility for the whole economy.
THE DISTRIBUTION SECTOR AND THE DEVELOPMENT PROCESS: ARE THERE PATTERNS? YES
Authors: Anderson James H. , Betancourt Roger R.
Published: July 2002

Using an increasing returns specification for distribution, an inverted U pattern between the share of distribution in gross domestic product and the level of development is shown to arise. A cross‐section time‐series data set is constructed and merged with one used to analyze the service sector. In contrast to the rising pattern found for services, an average time‐series relation that exhibits an inverted U pattern is established. The empirical results are robust, for example, to choice of functional form and country and time period coverage. A similar pattern is found in the average cross‐section (country) relation between distribution and development.
COLLUSION IN PROCUREMENT AUCTIONS: AN EXPERIMENTAL EXAMINATION
Authors: Davis Douglas D. , Wilson Bart J.
Published: July 2002

Experimental methods are used to examine the existence and detectability of collusion in environments that exhibit critical parallels to procurement auctions. We find that given the opportunity sellers often raise prices considerably. Moreover, noncollusive Nash equilibrium predictions are insufficient to dismiss “suspicious” behavior as innocuous: in an environment where identical prices are predicted in a noncollusive Nash equilibrium, common prices are observed only when sellers communicate. In a second environment designed to parallel construction procurement contracting, market rotations are observed both with and without collusion, but collusion can often be detected from the pattern of losing bids.
The [URE3] phenotype: evidence for a soluble prion in yeast
Authors: Fernandez‐Bellot Eric , Guillemet Elisabeth , Ness Frédérique , Baudin‐Baillieu Agnès , Ripaud Leslie , Tuite Mick , Cullin Christophe
Published: July 2002

The aggregation of the two yeast proteins Sup35p and Ure2p is widely accepted as a model for explaining the prion propagation of the phenotypes [PSI+] and [URE3], respectively. Here, we demonstrate that the propagation of [URE3] cannot simply be the consequence of generating large aggregates of Ure2p, because such aggregation can be found in some conditions that are not related to the prion state of Ure2p. A comparison of [PSI+] and [URE3] aggregation demonstrates differences between these two prion mechanisms. Our findings lead us to propose a new unifying model for yeast prion propagation.
A variational principle for the macroscopic theory of elastic type-II superconductors
Authors: Yeh C. S. , Chen K. C.
Published: July 2002

A variational principle is developed to investigate the behaviour of elastic type–II superconductors. It is shown that, with the proposed field Lagrangian and material–related Lagrangian, the governing equations and the associated boundary conditions in the thermodynamics equilibrium state can be obtained in a more systematic way. These results are consistent with those obtained by the continuum mechanics approach based on irreversible thermodynamics. A remark about the effect of the London moment which characterizes the local motion of a deformable superconductor is discussed. Furthermore, the effects of the magnetic flux flow or flux pinning are studied from the point of view of thermodynamics.
Neuromuscular control of prey capture in frogs
Authors: Nishikawa Kiisa C.
Published: July 2002

While retaining a feeding apparatus that is surprisingly conservative morphologically, frogs as a group exhibit great variability in the biomechanics of tongue protraction during prey capture, which in turn is related to differences in neuromuscular control. In this paper, I address the following three questions. (1) How do frog tongues differ biomechanically? (2) What anatomical and physiological differences are responsible? (3) How is biomechanics related to mechanisms of neuromuscular control? Frog species use three non–exclusive mechanisms to protract their tongues during feeding: (i) mechanical pulling, in which the tongue shortens as its muscles contract during protraction; (ii) inertial elongation, in which the tongue lengthens under inertial and muscular loading; and (iii) hydrostatic elongation, in which the tongue lengthens under constraints imposed by the constant volume of a muscular hydrostat. Major differences among these functional types include (i) the amount and orientation of collagen fibres associated with the tongue muscles and the mechanical properties that this connective tissue confers to the tongue as a whole; and (ii) the transfer of inertia from the opening jaws to the tongue, which probably involves a catch mechanism that increases the acceleration achieved during mouth opening. The mechanisms of tongue protraction differ in the types of neural mechanisms that are used to control tongue movements, particularly in the relative importance of feed–forward versus feedback control, in requirements for precise interjoint coordination, in the size and number of motor units, and in the afferent pathways that are involved in coordinating tongue and jaw movements. Evolution of biomechanics and neuromuscular control of frog tongues provides an example in which neuromuscular control is finely tuned to the biomechanical constraints and opportunities provided by differences in morphological design among species.
Acquisition of virulence-associated factors by the enteric pathogens
Escherichia coli
and
Salmonella enterica
Authors: Wain John , House Deborah , Pickard Derek , Dougan Gordon , Frankel Gad
Published: July 2002

In this review we summarize recent genomic studies that shed light on the mechanism through which pathogenic
Escherichia coli
and
Salmonella enterica
have evolved. We show how acquisition of DNA at specific sites on the chromosome has contributed to increased genetic variation and virulence of these two genera of the Enterobacteriaceae.
A Tale of Two Genotypes: Consistency between Two High-Throughput Genotyping Centers
Authors: Weeks Daniel E. , Conley Yvette P. , Ferrell Robert E. , Mah Tammy S. , Gorin Michael B.
Published: July 2002

Multiple genome-wide scans involving sib-pairs or limited pedigrees have been extensively used for a wide number of complex genetic conditions. Comparing data from two or more scans, as well as combining data, require an understanding of the sources of genotyping errors and data discrepancies. We have conducted two genome-wide scans for age-related maculopathy using the Center for Inherited Disease Research (CIDR) and the Mammalian Genotyping Service (MGS). Thirty individuals were typed in common, in order to allow for the alignment of alleles and comparison of the data sets. The analysis of these 8914 genotypes distributed over 321 markers in common demonstrated excellent agreement between these two laboratories, which have low rates of internal errors. Under the assumption that within each genotype, the smaller MGS allele should correspond to the smaller CIDR allele, the alleles align well between the two centers, with only a small fraction (less than 0.65%) of the aligned alleles showing large differences in sizes. However, since called allele sizes are integer “labels” which may not directly reflect the true underlying allele sizes, it is important to carefully prepare in advance if one wishes to merge data from different laboratories. In particular, it would not suffice to attempt to align alleles by typing only one or two controls in common. Fortunately, for the purposes of linkage analysis, one can avoid merging difficulties by simply carrying out linkage analyses using laboratory-specific allele labels and allele frequencies for each laboratory-specific subset of the data.
The elemental composition of tumors: Kerma data for neutrons
Authors: Maughan Richard L. , Chuba Paul J. , Porter Arthur T. , Ben‐Josef Edgar , Lucas David R.
Published: July 2002

The elemental composition of a variety of tumor samples, including squamous cell lung carcinoma, sarcoma, adenoid cystic carcinoma, melanoma, and rectal carcinoma have been measured by combustion analysis. Hydrogen, carbon, nitrogen, and oxygen content have been determined. Using the elemental neutron kerma data published in ICRU Report #46 the neutron kerma factors for the various tumor samples have been calculated in the energy range 11 eV to 29 MeV. The average neutron kerma values for all tumor samples are approximately 6%–7% lower than those for average soft tissue in the energy range of interest in fast neutron therapy (energies 1 MeV).
A simple experiment for discussion of quantum interference and which-way measurement
Authors: Schneider Mark B. , LaPuma Indhira A.
Published: July 2002

We have developed a which-way experiment using visible light that is completely analogous to a recent experiment involving which-way measurement in atom interference. This simple experiment, easily accessible to undergraduate students and the resources of undergraduate departments, facilitates the examination of the key elements of which-way measurement, quantum erasure, and related mysteries of quantum measurement. The experiment utilizes a Mach–Zehnder interferometer, and visually demonstrates the loss of interference fringes when a which-way measurement is imposed, and the restoration of that pattern when the which-way information is destroyed. This device is also sensitive enough to observe interference fringes arising from single photons. We present a simple analysis of the interference appropriate for the coherent classical field limit and the single photon limit at a level accessible to undergraduates. We also briefly mention related issues on the nature of the photon.
Bender transducer design and operation
Authors: Delany John L.
Published: July 2002

An empirical study covering a wide range of bender transducer sizes and operating frequencies is reported. A spherical device model is shown to give good account of bender performance, including interaction effects. A set of empirical rules for scaling equivalent circuit parameters according to the device geometry is identified. An effective spherical radius, approximately half the diaphragm radius, is identified for the typical bender. The effects of pressure and drive voltage on performance are described for particular devices. Sensitivity factors for the equivalent circuit parameters to the operating conditions are determined. These are related to sensitivity factors for the coupling coefficient (Kc) and electromechanical transformer turns ratio (N). Both these parameters are shown to have similar sensitivity responses, decreasing with pressure (planar stress), and increasing with voltage (electric field). The results of high drive tests carried out at Seneca Lake are reported. Values of conventional figures of merit (FOMV and FOMM), close to the highest claimed for any underwater transducer, are tabled. When allowance for the operating efficiency is included in the figure of merit definitions, the bender appears to be superior to other device types.
Generalized optical theorem for scatterers having inversion symmetry: Applications to acoustic backscattering
Authors: Marston Philip L.
Published: July 2002

The far-field acoustic scattering amplitudes for the scattering of plane waves by targets having inversion symmetry obey a generalized optical theorem in the absence of dissipation. The theorem allows a component of the complex scattering amplitude in an arbitrary direction to be expressed in terms of an angular integration involving scattering amplitudes evaluated at different angles. The result reduces to the usual optical theorem in the case of forward scattering. The theorem is applied to the backscattering by a perfectly soft sphere as a numerical example. The relevant integrand is shown to be oscillatory. Some potential applications to inverse problems, multiple scattering, and the verification of numerical algorithms are noted.
Dichotic pitches as illusions of binaural unmasking. II. The Fourcin pitch and the dichotic repetition pitch
Authors: Culling John F. , Marshall David H. , Summerfield A. Quentin
Published: July 2002

The predictions of three models are compared with respect to existing experimental data on the perception of the Fourcin pitch (FP) and the dichotic repetition pitch (DRP). Each model generates a central spectrum (CS), which is examined for peaks at frequencies consistent with the perceived pitches. A modified equalization-cancellation (mE-C) model of binaural unmasking [Culling and Summerfield, J. Acoust. Soc. Am. 98, 785–797 (1995)] generates a CS which reflects the degree of interaural decorrelation present in each frequency channel. This model accounts for the perceived frequencies of FPs, but produces no output for DRP stimuli. A restricted equalization-cancellation (rE-C) model [Bilsen and Goldstein, J. Acoust. Soc. Am. 55, 292–296 (1974)] sums the time-varying excitation in corresponding frequency channels, without equalization, to form a CS. A central activity pattern (CAP) model [Raatgever and Bilsen, J. Acoust. Soc. Am. 80, 429–441 (1986)] generates a CS by scanning an interaural cross-correlation matrix across frequency. The rE-C and CAP models yield inaccurate predictions of the perceived frequencies of FPs, but predict the occurrence of the DRP and its correct pitch. The complementary predictions of the mE-C model compared to the rE-C and CAP models, together with the evidence that the FP is clearly audible for the majority of listeners, while the DRP is faintly heard by a minority of listeners, suggest that the mE-C model provides the best available account of the FP, and that the DRP is produced by a separate mechanism.
Whistle signals of sturgeons and cetaceans
Authors: Tolstoganova Larissa K.
Published: July 2002

There are a lot of recordings of acoustic signals emitted by cetaceans and a few studies on sturgeon sounds. The signal analysis showed that all heard species of sturgeons and likewise cetaceans produce whistles and impulse signals consisting of broadband pulses. Sturgeon whistles may be separated into tone whistle with line spectrum, narrow-band whistle with narrow-band spectrum, FM whistle with narrow-band or broadband summary spectrum, and line or narrow-band instantaneous spectra. Acipenser stellatus, for example, emit tone and narrow-band signals consisting of one to seven components. The first component frequency is 2 to 3.5 kHz. The highest one is up to 16 kHz. Acipenser baeri and Acipenser guldenstadti emit all signal types. The frequency spectrum is up to 18 kHz. More often Acipenser Baeri produce FM whistles having one to five components which frequency varies directly as the square or cube of time. The minimal frequency of the first component is 1.0–3.5 kHz. The frequency range of the component is up to 2.5 kHz. Acipenser guldenstadti more often produce FM whistles having one to three components, which frequency varies inversely as the square root of time. The frequency range of the component is up to 7 kHz.
A semantic differential design especially developed for the evaluation of interior car sounds
Authors: Chouard Nicolas , Hempel Thomas
Published: July 2002

The use of semantic-differential (SD) procedure allows sound designers to compare interior car sounds on the basis of polarity profiles. In order to get representative information, SD designs have to be based on car-sound-specific verbal spaces. Due to the peculiarities of languages and conceptions of car culture in different countries, it is, moreover, not sufficient to use translated lists as they are available in the literature. In this contribution, the development of a representative verbal space for German subjects is presented. Two different approaches are used which are finally combined in order to get an intermediate list of adjective pairs. A representative and usable set of adjective pairs is established by reducing this list on the basis of SD tests with car sounds presented at the same loudness. The different steps and drawbacks in the development of the SD design are described and discussed. The components as well as the underlying dimensions of the verbal space are presented.
Rheological and Pipeline Flow Behavior of Corn Starch Dispersions
Authors: Griskey Richard G. , Nechrebecki D. G. , Notheis P. J. , Balmer R. T.
Published: July 2002

The rheological and pipeline flow behavior of corn starch dispersions has been studied. It was found that the flow characteristics of these systems gave dilatant (shear thickening) behavior until a critical shear rate was attained at which point Newtonian behavior commenced. This critical shear rate, as well as the behavior of power law index and consistency index were found to be functions of percent volume concentration. Additionally, the behavior of these rheological parameters was explained on the basis of an existing theory describing shear thickening. Pipeline flow data confirmed that dilatant (shear thickening) fluids followed the Metzner-Reed friction factor relationships in the laminar region. The range of behavior was extended to fluids having n values of 2.92 and volume concentrations of 40.0 percent. Finally, it was found that transition and turbulent flow could not be attained for dilatant (shear thickening) corn starch suspensions. This principally occurred because the critical shear rates yielding Newtonian behavior were excluded.
Cas9‐Geminin and Cdt1‐fused anti‐CRISPR protein synergistically increase editing accuracy
Authors: Matsumoto Daisuke , Kishi Kanae , Matsugi Erina , Inoue Yuto , Nigorikawa Kiyomi , Nomura Wataru
Published: March 2023

Genome editing with CRISPR‐Cas9, particularly for therapeutic purposes, should be accomplished via the homology‐directed repair (HDR) pathway, which exhibits greater precision than other pathways. However, one of the issues to be solved is that genome editing efficiency with HDR is generally low. A Streptococcus pyogenes Cas9 (SpyCas9) fusion with human Geminin (Cas9‐Gem) reportedly increases HDR efficiency slightly. In contrast, we found that regulation of SpyCas9 activity with an anti‐CRISPR protein (AcrIIA4) fused to Chromatin licensing and DNA replication factor 1 (Cdt1) significantly increases HDR efficiency and reduces off‐target effects. Here, another anti‐CRISPR protein, AcrIIA5, was applied, and the combined use of Cas9‐Gem and Anti‐CRISPR+Cdt1 showed synergistic enhancement of HDR efficiency. The method may be applicable to various anti‐CRISPR/CRISPR‐Cas combinations.
Understanding why searching the internet inflates confidence in explanatory ability
Authors: Eliseev Emmaline Drew , Marsh Elizabeth J.
Published: March 2023

People rely on the internet for easy access to information, setting up potential confusion about the boundaries between an individual's knowledge and the information they find online. Across four experiments, we replicated and extended past work showing that online searching inflates people's confidence in their knowledge. Participants who searched the internet for explanations rated their explanatory ability higher than participants who read but did not search for the same explanations. Two experiments showed that extraneous web page content (pictures) does not drive this effect. The last experiment modeled how search engines yield results; participants saw (but did not search for) a list of hits, which included “snippets” that previewed web page content, before reading the explanations. Participants in this condition were as confident as participants who searched online. Previewing hits primes to‐be‐read content, in a modern‐day equivalent of Titchener's famous example of a brief glance eliciting false feelings of familiarity.
An Experimental and Computational Modeling Study on Additively Manufactured Micro‐Architectured Ti–24Nb–4Zr–8Sn Hollow‐Strut Lattice Structures
Authors: Pramanik Sudipta , Milaege Dennis , Hein Maxwell , Andreiev Anatolii , Schaper Mirko , Hoyer Kay-Peter
Published: March 2023

Herein, the design, manufacturing, and mechanical testing of hollow‐strut lattice structures of the metastable β‐titanium alloy Ti–24Nb–4Zr–8Sn (Ti2448) are performed. Due to the absence of studies in the literature, this study focusses on two important aspects: 1) the designing of micro‐architectured lattice structures and 2) metastable β‐titanium alloy. Face‐centered cubic (FCC) and body‐centered cubic (BCC) hollow‐strut lattices are designed by computer‐aided design and manufactured by laser powder bed fusion. The microstructure of the hollow lattices shows plates of α″‐martensite phase within the β phase. The FCC hollow lattice structure shows higher tensile strength compared to the BCC hollow lattice structure, while the load‐bearing capability of the FCC hollow lattice structure is lower than that of the BCC hollow lattice structure. At lower strains, the tensile force‐displacement curve of the hollow lattice structure matches the simulated tensile force‐displacement curve. At higher strains, a large deviation in the force‐displacement curve is observed in the hollow lattices.
Highly Sensitive Strain Sensor Fabricated by Direct Laser Writing on Lignin Paper with Strain Engineering
Authors: Shen Li , Zhou Sikun , Gu Baoshan , Wang Sha , Wang Shutong
Published: March 2023

Paper‐based strain sensors (PSS) have broad prospects in disposable products due to their low cost and easy degradation as environmentally friendly materials. Herein, a strain sensor made of a laser‐induced carbonization electrode is created by direct laser writing with filter paper. The conductivity and gauge factor (GF) of this strain sensor are improved by adding lignin and applying strain engineering. This enables the sensor to simultaneously satisfy high sensitivity (GF ≈ 408 and 91) for weak tension and compression strain, respectively, and with long‐term reliability. The tensile strain GF factors of up to 201 are possible, even with a weak tensile strain of 0.00088%. Furthermore, the paper‐based sensor for monitoring physiological activities like finger gestures, pulsing, swallowing, and eye blinking is demonstrated. The facile fabrication and superior performance of PSS fabricated by direct laser writing with strain engineering may pave the way for promising applications of flexible, portable, and wearable electronic devices.
Forming Quality and Microstructure Evolution of AA6061‐T6 Aluminum Alloy Joint during Flow Drill Screwing Process
Authors: Huang Zhi-Chao , Huang Guo-Huang , Shan Feng-Wu , Jiang Yu-Qiang , Zou Yun-Qi , Nie Xiao-Yong
Published: March 2023

Flow drill screwing (FDS) is the optimal process to realize the single‐side connection of metal sheets. However, the plastic deformation and high fractional temperature during the plate connection process significantly impact the mechanical properties and microstructure of the metal sheets. Herein, the AA6061‐T6 sheet is connected by the FDS process, and the forming quality and microstructure evolution of the alloy are studied. The results show that the plate and the screw are mechanically connected. Obvious plastic deformation and recrystallization occur in the aluminum alloy around the screw, resulting in a fine‐grained zone near the joint interface. The recrystallization phenomenon in the central bushing region promotes the intermolecular fusion between the plates. The high temperature in the connection process partially promotes the dissolution of the strengthening phase, resulting in a decreased strength of the alloy matrix near the screw. The softening zone and hardening zone appear in the plates after the connection, and the hardness values are 55.8% and 105.7% of the alloy matrix.
Strong, Compressible, and Ultrafast Self‐Recovery Organogel with In Situ Electrical Conductivity Improvement
Authors: Zhang Songlin , Liu Mingyang , Guo Shuai , Tieu Aaron Jue Kang , Yang Jiachen , Adams Stefan , Tan Swee Ching
Published: March 2023

Coordination complexes are widely used to tune the mechanical behaviors of polymer materials, including tensile strength, stretchability, self‐healing, and toughness. However, integrating multivalent functions into one material system via solely coordination complexes is challenging, even using combinations of metal ions and polymer ligands. Herein, a single‐step process is described using silver‐based coordination complexes as cross‐linkers to enable high compressibility (>85%). The resultant organogel displays a high compressive strength (>1 MPa) with a low energy loss coefficient (<0.1 at 50% strain). Remarkably, it demonstrates an instant self‐recovery at room temperature with a speed >1200 mm s−1, potentially being utilized for designing high‐frequency‐responsive soft materials (>100 Hz). Importantly, in situ silver nanoparticles are formed, effectively endowing the organogel with high conductivity (550 S cm−1). Given the synthetic simplification to achieve multi‐valued properties in a single material system using metal‐based coordination complexes, such organogels hold significant potential for wearable electronics, tissue‐device interfaces, and soft robot applications.
Hydrogel‐Based Artificial Mucosa Restores Local Immune and Microbial Homeostasis for Treating Ulcerative Colitis
Authors: Wen Hong , Li Liqi , Ge Xinyue , Fei Yang , Li Yanan , Li Menghuan , Xiao Weidong , Luo Zhong
Published: March 2023

Ulcerative colitis (UC) is a common inflammatory bowel disease driven by the dyshomeostasis of intestinal immune system and microbiota, but its treatment options are limited due to impaired epithelial barrier integrity and function. Herein, a multifunctional biomimetic hydrogel is developed as artificial colonic mucosa, which can readily establish a bioadhesive barrier at the ulcer site and restore local immune and microbial homeostasis to exert potent anti‐inflammatory effect. The hydrogel framework is generated through the thrombin‐mediated activation and polymerization of fibrinogen that resembles natural blood coagulation mechanism. During this process, the antibacterial agent Ag+ is used for the crosslinking between the generated fibrin units and dopamine/thiol‐modified hyaluronic acid biopolymers via Ag+‐thiol coordination to convey enhanced bioadhesiveness, while the interconnected porous network is employed to encapsulate basic fibroblast growth factor (bFGF) and alanyl‐glutamine (ALG) for mucosa regeneration. The hydrogel stably adheres to the ulcer site to protect and repair the damaged epithelium and establishes an anti‐inflammatory microenvironment by inducing locoregional M1‐to‐M2 macrophage repolarization while eliminating harmful gut flora, which can act in a cooperative manner to substantially alleviate UC symptoms. The biomimetic hydrogel here presents a promising approach for effective UC therapy in the clinics.
Targeted Magnetic Resonance Imaging/Near‐Infrared Dual‐Modal Imaging and Ferroptosis/Starvation Therapy of Gastric Cancer with Peritoneal Metastasis
Authors: Guo Weihong , Ren Yingxin , Chen Zhian , Shen Guodong , Lu Yudie , Zhou Huimin , Li Zhenyuan , Li Zhenhao , Lu Xuanyi , Li Guoxin , Shen Zheyu , Hu Yanfeng
Published: March 2023

Accurate identification and visualization of peritoneal metastases (PM) are clinically essential to improving the prognosis for gastric cancer. However, owing to the multifocal spread of peritoneal metastasis nodules, small size, and close contact with adjacent organs, identifying and completely removing them during surgery is extremely challenging, resulting in cancer treatment failure and recurrence. This study develops a T1‐weighted magnetic resonance imaging (MRI) contrast agent (FeGdNP)‐loaded indocyanine green/glucose oxidase (ICG/GOx) with conjugation of an RGD dimer (RGD2) and acid‐labile polymer mPEG (FeGdNP‐ICG/GOx‐RGD2‐mPEG). Compared with commercial Magnevist, the proposed FeGdNP‐ICG/GOx‐RGD2‐mPEG shows a two to three‐fold higher tumor ΔSNR in MRI of peritoneal metastasis and subcutaneous animal models. Compared with free ICG, the increased fluorescent signal of FeGdNP‐ICG/GOx‐RGD2‐mPEG allows for the detection of tiny tumor metastatic nodules (<3 mm), and the removal of the peritoneum transplanted tumors. Abundant gluconic acid and H2O2 are generated during the GOx‐mediated glucose depletion process in cancer cells, thereby enhancing Fenton reaction efficiency. Accumulated toxic ·OH can damage the mitochondrial function and induce the release of mitochondrial reactive oxygen species, which activates the ferroptosis pathway. The data indicate the potential of the nanoparticles for MRI preoperative diagnosis, intraoperative fluorescence‐guided navigation, and ferroptosis tumor therapy.
Proton Conductor Confinement Strategy for Polymer Electrolyte Membrane Assists Fuel Cell Operation in Wide‐Range Temperature
Authors: Zhang Jujia , Chen Sian , Wei Haibing , Zhang Jin , Wang Haining , Lu Shanfu , Xiang Yan
Published: March 2023

Acid loss and plasticization of phosphoric acid (PA)‐doped polymer electrolyte membranes are critical hampers for its actual application especially during startup/shutdown stages due to the produced water and thermal stress. To conquer these barriers, a proton conductor confinement strategy is introduced, which may trap PA molecules in the side‐chain acidophilic microphase and weaken plasticizing effect caused by PA toward the polymer backbone to remain membrane tensile stress. The grafted polyphenylene oxide (PPO) is synthesized as model polymers, both molecular electrostatic potential and molecular dynamics reveal the retention mechanism between PA and side‐chain of PPO as well as the aggregation state of PA. Through precisely regulating polymer side‐chain structure and defined plasticization quantitative indicator, significant refinements in membrane's conductivity, durability, and single‐cell performance are achieved successfully. The designed PPO membranes exhibit ultra‐fast and stable proton conducting even at low proton carrier concentrations and under wide‐range working temperature between 80 oC–180 °C as well as satisfied resistance to harsh accelerated aging test. These insights will shed light on holistic understanding of PA interactions and retention from molecular level, and provide radical approaches toward high‐performance PA/PEMs design.
Synthesis of MnS/MnO Decorated N, S‐Doped Carbon Derived from a Mn(II)‐Coordinated Polymer for the Catalytic Oxidation of H2O2 and Bisphenol A
Authors: Shim Kyubin , Seo Kyeong‐Deok , Kim Hae Jin
Published: March 2023

A way to synthesize a Mn2+‐ coordinated polymer precursor ligated by sulfur atoms with acetate counter ions (Mn‐DTOGA) is proposed, which is achieved by an imine formation reaction between dithiooxamide and glutaraldehyde in the presence of manganese (II) acetate. MnS/MnO decorated N, S‐doped carbon nanoparticles (MnS/O‐SNC) are then prepared by calcination of the Mn ion‐coordinated polymer for the practical applications of catalytic reactions. The Mn‐DTOGA and MnS/O‐SNC structures prepared at different temperatures (700, 800, and 900 °C) are characterized using various physical and electrochemical and chemical analyses. The nanoparticles prepared at 900 °C reveal the best performance for the catalytic oxidation of Hydrogen peroxide (H2O2) and bisphenol A. The decomposition potentials of H2O2 (1.0 mm) and bisphenol A (100.0 µm) on the catalyst modified electrode are observed to be +0.40 and +0.15 V (versus Ag/AgCl), respectively. It is observed that the catalytic performances to the oxidation reactions are mainly related to MnO decorated outside the SNC particles compared to MnS formed inside the particles. The electrode reveals a wide dynamic range with the low detection limits for H2O2 (0.08 (±0.02) µm) and bisphenol A (0.17 (±0.04) µm). This study will provide essential clues for the future catalyst design.
Iron Oxyhydroxide: Structure and Applications in Electrocatalytic Oxygen Evolution Reaction
Authors: Guo Bingrong , Huo Haohao , Zhuang Qixuan , Ren Xiaoqian , Wen Xinxin , Yang Bolun , Huang Xiaoxiao , Chang Qiaowan , Li Siwei
Published: March 2023

Oxygen evolution reaction (OER) is the anodic half‐reaction for crucial energy devices, such as water electrolysis, metal–air battery, and electrochemical CO2 reduction. Fe‐based materials are recognized as one of the most promising electrocatalysts for OER because of its extremely low price and high activity. In particular, iron oxyhydroxide (FeOOH) is not only highly active toward OER, but also widely accepted as the true active species of Fe‐based OER electrocatalysts for plenty of Fe‐based materials are converted into FeOOH during OER test. Herein, the recent advances of FeOOH‐based nano‐structure and its application in OER are reviewed. The relationship between FeOOH structure and its catalytic performance, followed by the introduction of current strategies for enhancing the OER activity (i.e., crystalline phase engineering, element doping, and construction of hybrid materials) is mainly focused. Finally, a summary and perspective about the remaining challenges and future opportunities in this area and further the design of Fe‐based OER electrocatalysts are provided.
A Metal‐Free Mesoporous Carbon Dots/Silica Hybrid Type I Photosensitizer with Enzyme‐Activity for Synergistic Treatment of Hypoxic Tumor
Authors: Tian Boshi , Liu Shaohua , Yu Chenghao , Liu Shikai , Dong Shuming , Feng Lili , Hu Narisu , Yang Piaoping
Published: March 2023

As a less O2‐dependent photodynamic therapy (PDT), type I PDT is an effective approach to overcome the hypoxia‐induced low efficiency against solid tumors. However, the commonly used metal‐involved agents suffer from the long‐term biosafety concern. Herein, a metal‐free type I photosensitizer, N‐doped carbon dots/mesoporous silica nanoparticles (NCDs/MSN, ≈40 nm) nanohybrid with peroxidase (POD)‐like activity for synergistic PDT and enzyme‐activity treatment, is developed on gram scale via a facile one‐pot strategy through mixing carbon source and silica precursor with the assistance of template. Benefiting from the narrow bandgap (1.92 eV) and good charge separation capacity of NCDs/MSN, upon 640 nm light irradiation, the excited electrons in the conduction band can effectively generate O2•− by reduction of dissolved O2 via a one‐electron transfer process even under hypoxic conditions, inducing apoptosis of tumor cells. Moreover, the photoinduced O2•− can partially transform into more toxic •OH through a two‐electron reduction. Moreover, the POD‐like activity of NCDs/MSN can catalyze the endogenous H2O2 to •OH in the tumor microenvironment, further synergistically ablating 4T1 tumor cells. Therefore, a mass production way to synthesize a novel metal‐free type I photosensitizer with enzyme‐mimic activity for synergistic treatment of hypoxic tumors is provided, which exhibits promising clinical translation prospects.
Interstitial Cu: An Effective Strategy for High Carrier Mobility and High Thermoelectric Performance in GeTe
Authors: Yin Liang‐Cao , Liu Wei‐Di , Li Meng , Wang De‐Zhuang , Wu Hao , Wang Yifeng , Zhang Lixiong , Shi Xiao‐Lei , Liu Qingfeng , Chen Zhi‐Gang
Published: March 2023

Dense point defects can strengthen phonon scattering to reduce the lattice thermal conductivity and induce outstanding thermoelectric performance in GeTe‐based materials. However, extra point defects inevitably enlarge carrier scattering and deteriorate carrier mobility. Herein, it is found that the interstitial Cu in GeTe can result in synergistic effects, which include: 1) strengthened phonon scattering, leading to ultralow lattice thermal conductivity of 0.48 W m−1 K−1 at 623 K; 2) weakened carrier scattering, contributing to high carrier mobility of 80 cm2 V−1 s−1 at 300 K; 3) optimized carrier concentration of 1.22 × 1020 cm−3. Correspondingly, a high figure‐of‐merit of ≈2.3 at 623 K can be obtained in the Ge0.93Ti0.01Bi0.06Te‐0.01Cu, which corresponds to a maximum energy conversion efficiency of ≈10% at a temperature difference of 423 K. This study systematically investigates the doping behavior of the interstitial Cu in GeTe‐based thermoelectric materials for the first time and demonstrates that the localized interstitial Cu is a new strategy to enhance the thermoelectric performance of GeTe‐based thermoelectric materials.
Recent Progress in Advanced Hydrogel‐Based Embolic Agents: From Rational Design Strategies to Improved Endovascular Embolization
Authors: Li Xiaohong , Ullah Muhammad Wajid , Li Basen , Chen Hangrong
Published: March 2023

Transcatheter arterial embolization, a minimally invasive treatment to deliberately occlude the blood vessels, has become a safe and effective procedure for the management of vascular diseases and benign/malignant tumors. Particularly, hydrogel‐based embolic agents have garnered much attention because of their potential to address some of the limitations of clinically used embolic agents and can be rationally designed to impart more favorable characteristics or functions. In this review, the recent progress toward the development of polymer‐based hydrogels for effective endovascular embolization, including the in situ gelling hydrogels mediated by physically or chemically crosslinking, imageable hydrogels for intraprocedural and postprocedural feedback, use of hydrogels as the drug depot for local delivery of therapeutic drugs, hemostatic hydrogels inducing extrinsic or intrinsic coagulation of blood, stimuli‐responsive shape memory hydrogels as the smart embolization devices, and hydrogels incorporating external‐stimuli functional materials for multidisciplinary therapy, is systemically summarized. Moreover, the potential considerations of hydrogel‐based embolic agents confronted in therapeutic embolization are pointed out. Finally, the perspectives for the development of more effective embolic hydrogels are also highlighted.