bluuebunny/crossref_metadata_2025 huggingface dataset:
Protein Rearrangements Underlying Slow Inactivation of the Shaker K+ Channel
Authors: Loots E. , Isacoff E.Y.
Published: July 2002

Voltage-dependent ion channels transduce changes in the membrane electric field into protein rearrangements that gate their transmembrane ion permeation pathways. While certain molecular elements of the voltage sensor and gates have been identified, little is known about either the nature of their conformational rearrangements or about how the voltage sensor is coupled to the gates. We used voltage clamp fluorometry to examine the voltage sensor (S4) and pore region (P-region) protein motions that underlie the slow inactivation of the Shaker K+ channel. Fluorescent probes in both the P-region and S4 changed emission intensity in parallel with the onset and recovery of slow inactivation, indicative of local protein rearrangements in this gating process. Two sequential rearrangements were observed, with channels first entering the P-type, and then the C-type inactivated state. These forms of inactivation appear to be mediated by a single gate, with P-type inactivation closing the gate and C-type inactivation stabilizing the gate's closed conformation. Such a stabilization was due, at least in part, to a slow rearrangement around S4 that stabilizes S4 in its activated transmembrane position. The fluorescence reports of S4 and P-region fluorophore are consistent with an increased interaction of the voltage sensor and inactivation gate upon gate closure, offering insight into how the voltage-sensing apparatus is coupled to a channel gate.
Extensions of Hopf Algebras and Lie Bialgebras
Authors: Masuoka Akira
Published: July 2002

Let

f

\mathfrak {f}

,

g

\mathfrak {g}

be finite-dimensional Lie algebras over a field of characteristic zero. Regard

f

\mathfrak {f}

and

g

∗

\mathfrak {g} ^*

, the dual Lie coalgebra of

g

\mathfrak {g}

, as Lie bialgebras with zero cobracket and zero bracket, respectively. Suppose that a matched pair

(

f

,

g

∗

)

(\mathfrak {f} , \mathfrak {g} ^*)

of Lie bialgebras is given, which has structure maps

⇀
,
ρ

\rightharpoonup , \rho

. Then it induces a matched pair

(
U

f

,
U

g

∘

,

⇀
′

,

ρ
′

)

(U\mathfrak {f}, U\mathfrak {g}^{\circ },\rightharpoonup ’, \rho ’)

of Hopf algebras, where

U

f

U\mathfrak {f}

is the universal envelope of

f

\mathfrak {f}

and

U

g

∘

U\mathfrak {g}^{\circ }

is the Hopf dual of

U

g

U\mathfrak {g}

. We show that the group

O
p
e
x
t

(
U

f

,
U

g

∘

)

\mathrm {Opext} (U\mathfrak {f},U\mathfrak {g}^{\circ })

of cleft Hopf algebra extensions associated with

(
U

f

,
U

g

∘

,

⇀
′

,

ρ
′

)

(U\mathfrak {f}, U\mathfrak {g} ^{\circ }, \rightharpoonup ’, \rho ’ )

is naturally isomorphic to the group

Opext
⁡
(

f

,

g

∗

)

\operatorname {Opext}(\mathfrak {f},\mathfrak {g} ^*)

of Lie bialgebra extensions associated with

(

f

,

g

∗

,
⇀
,
ρ
)

(\mathfrak {f}, \mathfrak {g}^*, \rightharpoonup , \rho )

. An exact sequence involving either of these groups is obtained, which is a variation of the exact sequence due to G.I. Kac. If

g

=
[

g

,

g

]

\mathfrak {g} =[\mathfrak {g} , \mathfrak {g}]

, there follows a bijection between the set

E
x
t

(
U

f

,
U

g

∘

)

\mathrm {Ext}(U\mathfrak {f} , U\mathfrak {g}^{\circ })

of all cleft Hopf algebra extensions of

U

f

U\mathfrak {f}

by

U

g

∘

U\mathfrak {g}^{\circ }

and the set

E
x
t

(

f

,

g

∗

)

\mathrm {Ext}(\mathfrak {f}, \mathfrak {g}^*)

of all Lie bialgebra extensions of

f

\mathfrak {f}

by

g

∗

\mathfrak {g} ^*

.
On the affine heat equation for non-convex curves
Authors: Angenent Sigurd , Sapiro Guillermo , Tannenbaum Allen
Published: July 2002

In this paper, we extend to the non-convex case theaffine invariant geometric heat equationstudied by Sapiro and Tannenbaum for convex plane curves. We prove that a smooth embedded plane curve will converge to a point when evolving according to this flow. This result extends the analogy between the affine heat equation and the well-knownEuclidean geometric heat equation.
3DinSight: an integrated relational database and search tool for the structure, function and properties of biomolecules.
Authors: An J , Nakama T , Kubota Y , Sarai A
Published: July 2002

MOTIVATION: Although a large amount of information on the structure, function and properties of biomolecules is becoming available, it is difficult to understand the relationship between them. Thus, we have attempted to create an integrated relational database, search and visualization tool, 3DinSight, to help researchers to gain insight into their relationship. RESULTS: We have gathered data on the structure, function and properties of biomolecules, and implemented them into a relational database system. The structural data contain several subset data such as protein homologues, protein-DNA complex, in order to enable searching within a specific class of data. The functional data include motif sequence and mutation data of proteins. Also, various amino acid properties are implemented as a relational table. The World Wide Web (WWW) interfaces enable users to carry out various kinds of searches among these data. The locations of motif sequences and mutations are automatically mapped on the structure, and visualized in three-dimensional (3D) space by interactive viewers, VRML (Virtual Reality Modeling Language) and RasMol. In the case of VRML, the mapped 3D objects are hyper-linked to the corresponding document data. Also, amino acid properties, linked with structure, functional and mutation sites, can be displayed as graph plots. AVAILABILITY: 3DinSight is freely accessible through the Internet (http://www.rtc.riken.go.jp/3DinSight.h tml). CONTACT: sarai@rtc.riken.go.jp
Comparative analysis of seven multiple protein sequence alignment servers: clues to enhance reliability of predictions.
Authors: Briffeuil P , Baudoux G , Lambert C , De Bolle X , Vinals C , Feytmans E , Depiereux E
Published: July 2002

MOTIVATION: The prediction reliability of seven multiple alignment servers currently available on the Internet (ClustalW, MAP, PIMA, Block Maker, MSA, MEME and Match-Box) has been evaluated in terms of power (sensitivity) and confidence (selectivity). Therefore, the alignments obtained have been respectively compared to refined structural alignments for 20 families of related proteins with low levels of identity. RESULTS: Results clearly show that any powerful method remains reliable when the rate of identity falls. For some methods, power and confidence decrease linearly with the rate of identity, while other methods emphasize reliability at the cost of a lower power. Increasing the number of related sequences included in the alignment may either improve or decrease the quality of the predictions substantially. For some methods, the gain in power or in confidence is quite systematic; for others, the effect of the addition of homologous sequences is highly unpredictable. Extracting the consensus between two different methods may increase the overall confidence of the predictions tremendously. Our conclusions induce users of sequence alignment methods on the Internet to select the most suitable technique according to their requirements in terms of selectivity and sensitivity. AVAILABILITY: The aligned sequences of the 20 alignments of structure can be obtained automatically by sending the message 'send: cabios_tests.txt' by e-mail to 'matchbox@biq.fundp.ac.be'. CONTACT: eric.depiereux@fundp.ac.be
An integrated system for high throughput

TaqMan™ based SNP genotyping
Authors: Hampe Jochen , Wollstein Andreas , Lu Timothy , Frevel Hans-Jürgen , Will Marcus , Manaster Carl , Schreiber Stefan
Published: July 2002

Summary: We have developed an integrated laboratory information system that allows the flexible handling of pedigree, phenotype and genotype information. Specifically, it includes client applications for an integrated data import from TaqMan typing files, Mendel checking, data export, handling of pedigree and phenotype information and analysis features.

Availability: The SQL source code, sources and binaries of the client applications (NT and Windows95/98 platforms) and additional documentation are available at http://www.mucosa.de/.

Contact: J.Hampe@mucosa.de

* To whom correspondence should be addressed.
A dual role for the FtsK protein in Escherichia coli chromosome segregation
Authors: Capiaux Hervé , Lesterlin Christian , Pérals Koryn , Louarn Jean Michel , Cornet François
Published: July 2002

FtsK is a multifunctional protein that acts in Escherichia coli cell division and chromosome segregation. Its C‐terminal domain is required for XerCD‐mediated recombination between dif sites that resolve chromosome dimers formed by recombination between sister chromosomes. We report the construction and analysis of a set of strains carrying different Xer recombination sites in place of dif, some of which recombine in an FtsK‐independent manner. The results show that FtsK‐independent Xer recombination does not support chromosome dimer resolution. Furthermore, resolution of dimers by the Cre/loxP system also requires FtsK. These findings reveal a second role for FtsK during chromosome dimer resolution in addition to XerCD activation. We propose that FtsK acts to position the dif regions, thus allowing a productive synapse between dif sites.
Species-range size distributions: products of speciation, extinction and transformation
Authors: Gaston Kevin J.
Published: July 2002

One basic summary of the spatial pattern of biodiversity across the surface of the Earth is provided by a species–range size distribution, the frequency distribution of the numbers of species exhibiting geographic ranges of different sizes. Although widely considered to be approximately lognormal, increasingly it appears that across a variety of groups of organisms this distribution systematically departs from such a form. Whatever its detailed shape, however, the distribution must arise as a product of three processes, speciation, extinction and transformation (the temporal dynamics of the range sizes of species during their life times). Considering the role potentially played by each of these processes necessitates drawing on information from a diverse array of research fields, and highlights the possible role of geographic range size as a common currency uniting them.
The role of prefrontal cortex in working memory: examining the contents of consciousness
Authors:   The American Association for Research into Nervous and Mental Diseases, Courtney S. M. , Petit L. , Haxby J. V. , Ungerleider L. G.
Published: July 2002

Working memory enables us to hold in our ‘mind's eye’ the contents of our conscious awareness, even in the absence of sensory input, by maintaining an active representation of information for a brief period of time. In this review we consider the functional organization of the prefrontal cortex and its role in this cognitive process. First, we present evidence from brain–imaging studies that prefrontal cortex shows sustained activity during the delay period of visual working memory tasks, indicating that this cortex maintains on–line representations of stimuli after they are removed from view. We then present evidence for domain specificity within frontal cortex based on the type of information, with object working memory mediated by more ventral frontal regions and spatial working memory mediated by more dorsal frontal regions. We also propose that a second dimension for domain specificity within prefrontal cortex might exist for object working memory on the basis of the type of representation, with analytic representations maintained preferentially in the left hemisphere and image–based representations maintained preferentially in the right hemisphere. Furthermore, we discuss the possibility that there are prefrontal areas brought into play during the monitoring and manipulation of information in working memory in addition to those engaged during the maintenance of this information. Finally, we consider the relationship of prefrontal areas important for working memory, both to posterior visual processing areas and to prefrontal areas associated with long–term memory.
Evaluation of linear registration algorithms for brain SPECT and the errors due to hypoperfusion lesions
Authors: Radau Perry E. , Slomka Piotr J. , Julin Per , Svensson Leif , Wahlund Lars‐Olof
Published: July 2002

The semiquantitative analysis of perfusion single‐photon emission computed tomography (SPECT) images requires a reproducible, objective method. Automated spatial standardization (registration) of images is a prerequisite to this goal. A source of registration error is the presence of hypoperfusion defects, which was evaluated in this study with simulated lesions. The brain perfusion images measured by from 21 patients with probable Alzheimer's disease and 35 control subjects were retrospectively analyzed. An automatic segmentation method was developed to remove external activity. Three registration methods, robust least squares, normalized mutual information (NMI), and count difference were implemented and the effects of simulated defects were compared. The tested registration methods required segmentation of the cerebrum from external activity, and the automatic and manual methods differed by a three‐dimensional displacement of NMI registration proved to be least adversely effected by simulated defects with 3 mm average displacement caused by severe defects. The error in quantifying the patient‐template parietal ratio due to misregistration was 2.0% for large defects (70% hypoperfusion) and 0.5% for smaller defects (85% hypoperfusion).
An active set algorithm for treatment planning optimization
Authors: Hristov D. H. , Fallone B. G.
Published: July 2002

An active set algorithm for optimization of radiation therapy dose planning by intensity modulated beams has been developed. The algorithm employs a conjugate‐gradient routine for subspace minimization in order to achieve a higher rate of convergence than the widely used constrained steepest‐descent method at the expense of a negligible amount of overhead calculations. The performance of the new algorithm has been compared to that of the constrained steepest‐descent method for various treatment geometries and two different objectives. The active set algorithm is found to be superior to the constrained steepest descent, both in terms of its convergence properties and the residual value of the cost functions at termination. Its use can significantly accelerate the design of conformal plans with intensity modulated beams by decreasing the number of time‐consuming dose calculations.
Optimal noise control in and fast reconstruction of fan‐beam computed tomography image
Authors: Pan Xiaochuan
Published: July 2002

We proposed a linear approach that exploits statistically complementary information inherent in the projection data of fan‐beam computed tomography (CT) for achieving a bias‐free image‐variance reduction in fan‐beam CT. This linear approach leads to the development of infinite classes of hybrid algorithms for image reconstruction in fan‐beam CT. These hybrid algorithms are computationally more efficient and numerically less susceptible to data noise and to the effect of finite sampling than the conventional fan‐beam filtered back‐projection (FFBP) algorithm. We also developed infinite classes of generalized fan‐beam filtered back‐projection (GFFBP) algorithms, which include the conventional FFBP algorithm as a special member. We demonstrated theoretically and quantitatively that the hybrid and GFFBP algorithms are identical (or different) in the absence (or presence) of data noise and of the effect of finite sampling. More importantly, we identified the statistically optimal hybrid algorithm that may have potentially significant implication to image reconstruction in fan‐beam CT. Extensive numerical results of computer‐simulation studies validated our theoretical results.
Galileo’s discovery of scaling laws
Authors: Peterson Mark A.
Published: July 2002

Galileo’s realization that nature is not scale invariant motivated his subsequent discovery of scaling laws. His thinking is traced to two lectures he gave on the geography of Dante’s Inferno.
Target parameter estimation using resonance scattering analysis applied to air-filled, cylindrical shells in water
Authors: Tesei A. , Fox W. L. J. , Maguer A. , Lo/vik A.
Published: July 2002

Current research on classification of submerged objects is concerned with using broadband sonar signals to insonify the targets, and applying signal-processing techniques to the backscattered signals. One characteristic of target echoes which may provide classification clues is the so-called resonance scattering response, the characteristics of which depend on target elastic properties. This paper presents algorithms for extracting resonance information based on autoregressive (AR) spectral estimation techniques. The AR-based representation is useful for detecting and accurately localizing resonances in the frequency domain. The extracted resonance frequencies are grouped into identified wave families, and processed in order to characterize the scatterer in terms of elastic and geometrical parameters on the basis of equations derived from resonance scattering theory. The targets considered are water-loaded elastic, cylindrical, thin-walled shells immersed in salt water under free-field conditions. Analysis was performed on data collected at sea at low-intermediate frequencies [ka∈(0,50)] and provided good results. The proposed approach is a first step towards the characterization of more complex targets either lying proud on the seabed or buried in bottom sediments.
Irregular vocal-fold vibration—High-speed observation and modeling
Authors: Mergell Patrick , Herzel Hanspeter , Titze Ingo R.
Published: July 2002

Direct observations of nonstationary asymmetric vocal-fold oscillations are reported. Complex time series of the left and the right vocal-fold vibrations are extracted from digital high-speed image sequences separately. The dynamics of the corresponding high-speed glottograms reveals transitions between low-dimensional attractors such as subharmonic and quasiperiodic oscillations. The spectral components of either oscillation are given by positive linear combinations of two fundamental frequencies. Their ratio is determined from the high-speed sequences and is used as a parameter of laryngeal asymmetry in model calculations. The parameters of a simplified asymmetric two-mass model of the larynx are preset by using experimental data. Its bifurcation structure is explored in order to fit simulations to the observed time series. Appropriate parameter settings allow the reproduction of time series and differentiated amplitude contours with quantitative agreement. In particular, several phase-locked episodes ranging from 4:5 to 2:3 rhythms are generated realistically with the model.
Frequency dependence of ultrasonic backscattering in cancellous bone: Autocorrelation model and experimental results
Authors: Chaffaı̈ S. , Roberjot V. , Peyrin F. , Berger G. , Laugier P.
Published: July 2002

The goal of this study is to model the frequency dependence of the ultrasonic backscatter coefficient in cancellous bone. A twofold theoretical approach has been adopted: the analytical theoretical model of Faran for spherical and cylindrical elastic scatterers, and the scattering model for weakly scattering medium in which the backscatter coefficient is related to the autocorrelation function of the propagating medium. The ultrasonic backscatter coefficient was measured in 19 bone specimens (human calcaneae) in the frequency range of 0.4–1.2 MHz. The autocorrelation function was computed from the three-dimensional (3D) microarchitecture measured using synchrotron radiation microtomography. Good agreement was found between the frequency dependence of the experimental (f3.38±0.31) and autocorrelation modeled (f3.48±0.26) backscatter coefficients. The results based on Faran theory (cylindrical Faran model: f2.89±0.06 and spherical Faran model: f3.91±0.04) show qualitative agreement with experimental data. The good prediction obtained by modeling the backscatter coefficient using the autocorrelation function of the medium opens interesting prospects for the investigation of the influence of bone microarchitecture on ultrasonic scattering.
Reduction of electronic delay in active noise control systems— A multirate signal processing approach
Authors: Bai Mingsian R. , Lin Yuanpei , Lai Jienwen
Published: July 2002

Electronic delay has been a critical problem in active noise control (ANC) systems. This is true whether a feedforward structure or a feedback structure is adopted. In particular, excessive delays would create a causality problem in a feedforward ANC system of a finite-length duct. This paper suggests a multirate signal-processing approach for minimizing the electronic delay in the control loop. In this approach, digital controllers are required in decimation and interpolation of discrete-time signals. The computation efficiency is further enhanced by a polyphase method, where the phases of low-pass finite impulse response (FIR) filters must be carefully designed to avoid unnecessary delays. Frequency domain optimization procedures based on H1, H2, and H∞ norms, respectively, are utilized in the FIR filter design. The proposed method was implemented by using a floating-point digital signal processor. Experimental results showed that the multirate approach remains effective for suppressing a broadband (200–600 Hz) noise in a duct with a minimum upstream measurement microphone placement of 20 cm.
Characterization of a diffuse field in a reverberant room
Authors: Nélisse H. , Nicolas J.
Published: July 2002

An efficient modal approach to characterize the diffuseness of the sound field in a rectangular room is presented. Using two simple descriptors, the correlation function and the spatial uniformity of the pressure field, a practical and convenient tool is proposed to study the diffuse field in the room. A precise criterion has been given in terms of the least permissible number of room modes to achieve an adequate diffusion. It has been shown that the criterion is in great accordance with the well-known “Schroeder frequency” limit for the diffuse field. Detailed calculations of the correlation function are presented to show the importance of the Δk/k correction terms to the well-known sin(kR)/kR prediction. A new closed form for the correlation function is thus derived. A discussion about the importance of having more than one descriptors is also presented. It is shown that a diffuse field can be established in a room with strong modal behavior under certain assumptions.
Inverse scattering from arbitrary two-dimensional objects in stratified environments via a Green’s operator
Authors: Wiskin James W. , Borup David T. , Johnson Steven A.
Published: July 2002

An important problem in geophysics, medical imaging, and nondestructive imaging today is the construction of a practical, accurate, and efficient means of imaging geophysical anomalies, tumours, or material defects in layered media. This paper discusses such a method. The use of a “stratified Green’s function” for the solution of the forward problem is detailed. This forward problem is then incorporated into an efficient and accurate inversion algorithm based on optimization. The method is nonperturbative, unlike diffraction tomography, which relies on linearization to make the problem tractable. In the inversion, a pair of Lippmann–Schwinger-like integral equations are solved simultaneously via the Galerkin procedure for the unknown total internal fields and speed distribution. The computational burden is high, but made manageable by utilizing BiConjugate gradients, fast fourier transforms, and “sinc” basis functions to speed up the solution of the forward problem. The size and contrasts for which the method converges are substantially beyond the Born or Rytov approximations, and other methods heretofore reported in the literature. The convolutional character of the layered Green’s function, and thus numerical efficiency, is preserved by careful construction based on known reflection coefficients.
In vitro characterization of a novel, tissue-targeted ultrasonic contrast system with acoustic microscopy
Authors: Lanza Gregory M. , Trousil Rebecca L. , Wallace Kirk D. , Rose James H. , Hall Christopher S. , Scott Michael J. , Miller James G. , Eisenberg Paul R. , Gaffney Patrick J. , Wickline Samuel A.
Published: July 2002

Targeted ultrasonic contrast systems are designed to enhance the reflectivity of selected tissues in vivo [Lanza et al., Circulation 94, 3334 (1996)]. In particular, these agents hold promise for the minimally invasive diagnosis and treatment of a wide array of pathologies, most notably tumors, thromboses, and inflamed tissues. In the present study, acoustic microscopy was used to assess the efficacy of a novel, perfluorocarbon based contrast agent to enhance the inherent acoustic reflectivity of biological and synthetic substrates. Data from these experiments were used to postulate a simple model describing the observed enhancements. Frequency averaged reflectivity (30–55 MHz) was shown to increase 7.0±1.1 dB for nitrocellulose membranes with targeted contrast. Enhancements of 36.0±2.3 dB and 8.5±0.9 dB for plasma and whole blood clots, respectively, were measured between 20 and 35 MHz. A proposed acoustic transmission line model predicted the targeted contrast system would increase the acoustic reflectivity of the nitrocellulose membrane, whole blood clot, and fibrin plasma clot by 2.6, 8.0, and 31.8 dB, respectively. These predictions were in reasonable agreement with the experimental results of this paper. In conclusion, acoustic microscopy provides a rapid and sensitive approach for in vitro characterization, development, and testing of mathematical models of targeted contrast systems. Given the current demand for targeted contrast systems for medical diagnostic and therapeutic use, the use of acoustic microscopy may provide a useful tool in the development of these agents.
Modeling the role of nonhuman vocal membranes in phonation
Authors: Mergell Patrick , Fitch W. Tecumseh , Herzel Hanspeter
Published: July 2002

Although the mammalian larynx exhibits little structural variation compared to sound-producing organs in other taxa (birds or insects), there are some morphological features which could lead to significant differences in acoustic functioning, such as air sacs and vocal membranes. The vocal membrane (or “vocal lip”) is a thin upward extension of the vocal fold that is present in many bat and primate species. The vocal membrane was modeled as an additional geometrical element in a two-mass model of the larynx. It was found that vocal membranes of an optimal angle and length can substantially lower the subglottal pressure at which phonation is supported, thus increasing vocal efficiency, and that this effect is most pronounced at high frequencies. The implications of this finding are discussed for animals such as bats and primates which are able to produce loud, high-pitched calls. Modeling efforts such as this provide guidance for future empirical investigations of vocal membrane structure and function, can provide insight into the mechanisms of animal communication, and could potentially lead to better understanding of human clinical disorders such as sulcus vocalis.
Oscillations of polymeric microbubbles: Effect of the encapsulating shell
Authors: Hoff Lars , Sontum Per C. , Hovem Jens M.
Published: July 2002

A model for the oscillation of gas bubbles encapsulated in a thin shell has been developed. The model depends on viscous and elastic properties of the shell, described by thickness, shear modulus, and shear viscosity. This theory was used to describe an experimental ultrasound contrast agent from Nycomed, composed of air bubbles encapsulated in a polymer shell. Theoretical calculations were compared with measurements of acoustic attenuation at amplitudes where bubble oscillations are linear. A good fit between measured and calculated results was obtained. The results were used to estimate the viscoelastic properties of the shell material. The shell shear modulus was estimated to between 10.6 and 12.9 MPa, the shell viscosity was estimated to between 0.39 and 0.49 Pas. The shell thickness was 5% of the particle radius. These results imply that the particles are around 20 times more rigid than free air bubbles, and that the oscillations are heavily damped, corresponding to Q-values around 1. We conclude that the shell strongly alters the acoustic behavior of the bubbles: The stiffness and viscosity of the particles are mainly determined by the encapsulating shell, not by the air inside.
The role of sentential prosody in learning voices
Authors: Nygaard Lynne C. , Queen Jennifer S.
Published: July 2002

The present experiment was designed to investigate the contribution of sentential prosody to the perceptual learning of talker’s voice. Listeners were trained over a three-day period to learn talker’s voices from three types of utterances: (1) sentence-length utterances produced with natural sentential prosody, (2) utterances in which individual words were produced in list format and digitally assembled into complete sentences, and (3) words produced in list format and scrambled to remove semantic and syntactic coherence. Equal numbers of male and female listeners learned a set of ten talker’s voices (five male and five female) and learning was evaluated at each training session. On the fourth day of testing, listeners were given a generalization test that consisted of novel sentence-length utterances produced with natural sentential prosody. Results indicated that learning curves were comparable across conditions, but the ability to generalize to new utterances depended on the utterance type used during training. Individual differences among both listeners and talkers were also observed. Male listeners identified male voices significantly better than female voices. Female listeners identified male and female voices equally well. These results suggest that the perception of talker identity is dependent both on listener- and task-specific characteristics.
Discontinuous and Dilatant Viscosity Behavior in Concentrated Suspensions. I. Observation of a Flow Instability
Authors: Hoffman R. L.
Published: July 2002

The rheological dilatancy of concentrated suspensions has been studied to determine the cause of this phenomenon. If monodisperse suspensions of polymeric resins are examined, dilatant viscosity behavior is transformed into a discontinuous viscosity behavior when the volume fraction of solids is raised above 0.50. Experimental evidence is presented which supports the hypothesis that the discontinuity is caused by a flow instability in which surfaces of spheres, packed in a two dimensional hexagonal packing at low shear rates, break up into less ordered arrays of spheres. Although various techniques have been used, white light diffraction from a suspension under shear provides the most dramatic evidence of the ordered packing of the spheres and the order-disorder transition at the instability point.
An analytical relation between relaxation time spectrum and molecular weight distribution
Authors: Thimm Wolfgang , Friedrich Christian , Marth Michael , Honerkamp Josef
Published: July 2002

In this article it is shown that the relaxation time spectrum can be analytically related to the molecular weight distribution regarding a recently derived generalized mixing rule. This analytical relation greatly reduces the computational effort to determine the molecular weight distribution from the relaxation time spectrum. In this mixing rule a generalized mixing parameter β has been introduced. This parameter has been controversially discussed in the literature. The value of β has been determined theoretically by [The Theory of Polymer Dynamics (Clarendon, Oxford, 1986)] as β=1 and [Europhys. Lett. 5, 437–442 (1988); 6, 475 (1988)] and [Polym. Prepr. (Am. Chem. Soc. Div. Polym. Chem.) 28, 185–186 (1987)] (β=2) and experimentally by [J. Rheol. 42, 1153–1173 (1998)] (β=3.84). In this article the influence of β on shape and position of peaks in bimodal molecular weight distributions is emphasized.
Raman imaging of rat nonalcoholic fatty liver tissues reveals distinct biomolecular states
Authors: Helal Khalifa Mohammad , Cahyadi Harsono , Taylor J. Nicholas , Okajima Akira , Tabata Koji , Kumamoto Yasuaki , Mochizuki Kentaro , Itoh Yoshito , Takamatsu Tetsuro , Tanaka Hideo , Fujita Katsumasa , Komatsuzaki Tamiki , Harada Yoshinori
Published: February 2023

An essential challenge in diagnosing states of nonalcoholic fatty liver disease (NAFLD) is the early prediction of progression from nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH) before the disease progresses. Histological diagnoses of NAFLD rely on the appearance of anomalous tissue morphologies, and it is difficult to segment the biomolecular environment of the tissue through a conventional histopathological approach. Here, we show that hyperspectral Raman imaging provides diagnostic information on NAFLD in rats, as spectral changes among disease states can be detected before histological characteristics emerge. Our results demonstrate that Raman imaging of NAFLD can be a useful tool for histopathologists, offering biomolecular distinctions among tissue states that cannot be observed through standard histopathological means.
The ABC transporter family efflux pump PvdRT‐OpmQ of Pseudomonas putida KT2440: purification and initial characterization
Authors: Stein Nicola Victoria , Eder Michelle , Brameyer Sophie , Schwenkert Serena , Jung Heinrich
Published: February 2023

Tripartite efflux systems of the ABC‐type family transport a variety of substrates and contribute to the antimicrobial resistance of Gram‐negative bacteria. PvdRT‐OpmQ, a member of this family, is thought to be involved in the secretion of the newly synthesized and recycled siderophore pyoverdine in Pseudomonas species. Here, we purified and characterized the inner membrane component PvdT and the periplasmic adapter protein PvdR of the plant growth‐promoting soil bacterium Pseudomonas putida KT2440. We show that PvdT possesses an ATPase activity that is stimulated by the addition of PvdR. In addition, we provide the first biochemical evidence for direct interactions between pyoverdine and PvdRT.
Elevated CO2 levels did not induce species- or tissue-specific damage in young-of-year salmonids
Authors: Traynor Emma M. , Hasler Caleb T.
Published: February 2023

Objective

The broad objective of our study was to use a histological approach to examine possible tissue-level effects of exposure to elevated CO2 in freshwater young-of-year salmonids.

Methods

To study these effects, young-of-year Arctic Char Salvelinus alpinus, Rainbow Trout Oncorhynchus mykiss, and Brook Trout S. fontinalis were exposed to either control levels of CO2 (1400 μatm) or elevated levels of CO2 (5236 μatm) for 15 days. Fish were then sampled for gill, liver, and heart tissues and histologically analyzed.

Result

A species effect was observed for the length of secondary lamellae, as Arctic Char had significantly shorter secondary lamellae than the other species. No notable changes within the gills and livers of Arctic Char, Brook Trout, or Rainbow Trout exposed to elevated CO2 were observed.

Conclusion

Generally, our results indicated that elevated CO2 levels over 15 days do not induce catastrophic tissue damage and it is unlikely that fish health would be seriously impacted. Ongoing research dedicated to examining how elevated CO2 long-term may affect internal tissues of fish will allow for a more comprehensive understanding of how fish may fair with ongoing climate change and in aquaculture facilities.
Effect of Carbon Content on the Microstructure and Mechanical Properties of GH3230 Alloy Formed by Laser Melting Deposition
Authors: Dong Yang , Hao Mingsong , Mu Yahang , Liang Jingjing , Qiu Keqiang , Li Jinguo
Published: February 2023

Optimizing alloy composition is an effective way to improve the microstructure and properties of superalloys. Herein, the influence of carbon content (0.071, 0.105, and 0.136 wt%, respectively) on the microstructure and mechanical properties of GH3230 alloy formed by laser melting deposition is investigated. The results indicate that the carbon contents affect the quantity, morphology, and distribution of carbides in the matrix of the alloy. As the carbon content increases, the number of carbides increases, and the morphology of the carbides at the grain boundaries changes from discontinuous blocks to chains, and finally into strips. Three alloys with high plasticity at room temperature, and the maximum elongation close to 60% is achieved for alloy containing 0.105 wt% C. The high‐temperature elongation of the alloy also increases at first and then decreases with the carbon. It is therefore concludes that the optimized carbon content is 0.105 wt% by combining both the strength and plasticity for GH3230 alloy prepared by laser melting deposition.
Nucleotide‐Driven Molecular Sensing of Monkeypox Virus Through Hierarchical Self‐Assembly of 2D Hafnium Disulfide Nanoplatelets and Gold Nanospheres
Authors: Moitra Parikshit , Iftesum Maria , Skrodzki David , Paul Priyanka , Sheikh Elnaz , Gray Jennifer Lynn , Dighe Ketan , Sheffield Zach , Gartia Manas Ranjan , Pan Dipanjan
Published: February 2023

Liquid interfaces facilitate the organization of nanometer‐scale biomaterials with plasmonic properties suitable for molecular diagnostics. Using hierarchical assemblage of 2D hafnium disulfide nanoplatelets and zero‐dimensional spherical gold nanoparticles, the design of a multifunctional material is reported. When the target analyte is present, the nanocomposites’ self‐assembling pattern changes, altering their plasmonic response. Using monkeypox virus (MPXV) as an example, the findings reveal that adding genomic DNA to the nanocomposite surface increases the agglomeration between gold nanoparticles and decreases the π‐stacking distance between hafnium disulfide nanoplatelets. Further, this self‐assembled nanomaterial is found to have minimal cross‐reactivity toward other pathogens and a limit of detection of 7.6 pg µL−1 (i.e., 3.57 × 104 copies µL−1) toward MPXV. Overall, this study helped to gain a better understanding of the genomic organization of MPXV to chemically design and develop targeted nucleotides. The study has been validated by UV–vis spectroscopy, X‐ray diffraction, scanning transmission electron microscopy, surface‐enhanced Raman microscopy and electromagnetic simulation studies. To the best knowledge, this is the first study in literature reporting selective molecular detection of MPXV within a few minutes and without the use of any high‐end instrumental techniques like polymerase chain reactions.
Telecom‐Wavelength Organic Single‐Crystal Lasers Triggered by the Molecular Conformation‐Dependent Cascaded Proton Transfer Processes
Authors: Wu Jun‐Jie , Yu Shuwen , Liu Yanping , Yan Chang‐Cun , Yang Wan‐Ying , Xie Wanfeng , Wang Xue‐Dong , Sun Chaofan , Liao Liang‐Sheng
Published: February 2023

Organic semiconductor molecules possess chemical tunability and large stimulated emission cross section, representing a promising candidate for laser gain medium. However, for the pursuit of telecom‐wavelength organic lasers, one of the major obstacles is the lack of effective energy‐level systems with high optical gain to compensate the exciton deactivation losses. Herein, the effects of molecular conformation‐dependent distinct cascaded proton‐transfer six‐level energy gain systems on lasing emission properties are systematically investigated based on organic polymorphs, proving that an energy‐level gain system without reversible transition channels is more conducive to the formation of efficient population inversion and high optical gain. Notably, the one‐way irreversible six‐level energy system of β‐phase polymorph supports more favorable population inversions than the two‐way reversible six‐level system of α‐phase polymorph due to the irreversible excited‐state second proton transfer and the irreversible ground‐state recovery, achieving the amplified spontaneous emission at telecom‐wavelength of ≈850 nm. This study provides useful guidelines for constructing efficient energy‐level gain systems, promoting the exploration of high‐gain organic semiconductor laser materials from visible to near‐infrared region.
Bidirectional Targeted Therapy Enables Efficient, Stable, and Eco‐Friendly Perovskite Solar Cells
Authors: Qi Xingnan , Song Chongping , Zhang Weihai , Shi Yueqing , Gao Yueyue , Liu Heng , Chen Rui , Shang Luwen , Tan Hairen , Tan Furui , Wang Hsing‐Lin
Published: February 2023

Perovskite solar cells (PSCs) have witnessed rapid development toward commercialization based on their superior efficiency except for some remained misgivings about their poor stability primarily originating from interfacial problems. Robust back interface for neutralization of crystal defects, depression of dopant lithium ions (Li+) diffusion, and even inhibition of toxic lead (Pb) leakage is highly desirable; however, it remains a great challenge. Herein, a cost‐effective interfacial therapy approach is developed to simultaneously alleviate the obstacles aforementioned. A small molecule, 1,4‐dithiane with unique chair structure, is adapted to interact with under‐coordinated Pb2+ on perovskite surface and Li+ from hole transport layer, neutralizing interfacial defects and suppressing Li+ diffusion. Besides, the presence of 1,4‐dithiane can efficiently modulate interfacial energetics, enhance hydrophobicity of PSCs, and anchor Pb atoms via SPb bond. Consequently, the target devices perform better than control devices when exposed to light‐soaking, moisture, and thermal stress owing to the synergistic suppression of trap‐state density, ions migration, and moisture permeation. The optimized target device delivers a champion efficiency of 23.27% with mitigated Pb leakage. This study demonstrates a promising functionalized modification strategy for constructing efficient, stable, and eco‐friendly PSCs.
White Light and Color‐Tuning Long Persistent Luminescence from Metal Halide Based Metal‐Organic Frameworks
Authors: Wang Zheng , Mo Jun‐Ting , Pan Jun‐Jie , Pan Mei
Published: February 2023

Room temperature phosphorescence (RTP) materials with long persistent luminescence (LPL) have raised particular attention among researchers for their potential uses in chemical sensing, optical recording devices, biological imaging, and security systems applications, due to the long‐lived triplet states. In this study, one‐pot method of reaction of appropriate ratio of crown ether ligand (15‐Crown‐5) and metallic salts (CdX2) is utilized to yield three metal halide‐based complexes (namely 15‐5‐CdCl2, 15‐5‐CdBr2, and 15‐5‐CdI2). In solid state, three complexes exhibit nearly standard white light emission with CIE coordinates of (0.28, 0.32), (0.31, 0.39), (0.30, 0.34) at room temperature under UV radiation of 340 nm. Meanwhile, they display the excitation‐dependent room temperature phosphorescence from blue/cyan to green/yellow, especially, 15‐5‐CdCl2 and 15‐5‐CdBr2 exhibit color‐tunable and visible LPL with time‐resolved luminescence lifetime as high as 1–2 s. Single‐crystal X‐ray diffraction analysis and theoretical calculations reveal that the bright LPL of 15‐5‐CdCl2 and 15‐5‐CdBr2 arise from the crown ether ligand and aggregation state induced by halogen‐bond. The thus obtained LPL provides potentials in lighting and displaying devices, optical recording devices, security systems and so on.
A Self‐Powered, Rechargeable, and Wearable Hydrogel Patch for Wireless Gas Detection with Extraordinary Performance
Authors: Wu Zixuan , Wang Hao , Ding Qiongling , Tao Kai , Shi Wenxiong , Liu Chuan , Chen Jun , Wu Jin
Published: February 2023

Flexible gas sensors play an indispensable role in diverse applications spanning from environmental monitoring to portable medical electronics. Full wearable gas monitoring system requires the collaborative support of high‐performance sensors and miniaturized circuit module, whereas the realization of low power consumption and sustainable measurement is challenging. Here, a self‐powered and reusable all‐in‐one NO2 sensor is proposed by structurally and functionally coupling the sensor to the battery, with ultrahigh sensitivity (1.92%/ppb), linearity (R2 = 0.999), ultralow theoretical detection limit (0.1 ppb), and humidity immunity. This can be attributed to the regulation of the gas reaction route at the molecular level. The addition of amphiphilic zinc trifluoromethanesulfonate (Zn(OTf)2) enables the H2O‐poor inner Helmholtz layer to be constructed at the electrode–gel interface, thereby facilitating the direct charge transfer process of NO2 here. The device is then combined with a well‐designed miniaturized low‐power circuit module with signal conditioning, processing and wireless transmission functions, which can be used as wearable electronics to realize early and remote warning of gas leakage. This study demonstrates a promising way to design a self‐powered, sustainable, and flexible gas sensor with high performance and its corresponding wireless sensing system, providing new insight into the all‐in‐one system of gas detection.
AIEgens/Mitochondria Nanohybrids as Bioactive Microwave Sensitizers for Non‐Thermal Microwave Cancer Therapy
Authors: Yu Xinghua , Lyu Ming , Ou Xupei , Liu Wenquan , Yang Xing , Ma Xiaoxi , Zhang Tianfu , Wang Longnan , Zhang Ying‐Chuan , Chen Sijie , Kwok Ryan T. K. , Zheng Zheng , Cui Hong‐Liang , Cai Lintao , Zhang Pengfei , Tang Ben Zhong
Published: February 2023

Aggregation‐induced emission luminogens (AIEgens) are widely used as photosensitizers for image‐guided photodynamic therapy (PDT). Due to the limited penetration depth of light in biological tissues, the treatments of deep‐seated tumors by visible‐light‐sensitized aggregation‐induced emission (AIE) photosensitizers are severely hampered. Microwave dynamic therapy attracts much attention because microwave irradiation can penetrate very deep tissues and sensitize the photosensitizers to generate reactive oxygen species (ROS). In this work, a mitochondrial‐targeting AIEgen (DCPy) is integrated with living mitochondria to form a bioactive AIE nanohybrid. This nanohybrid can not only generate ROS under microwave irradiation to induce apoptosis of deep‐seated cancer cells but also reprogram the metabolism pathway of cancer cells through retrieving oxidative phosphorylation (OXPHOS) instead of glycolysis to enhance the efficiency of microwave dynamic therapy. This work demonstrates an effective strategy to integrate synthetic AIEgens and natural living organelles, which would inspire more researchers to develop advanced bioactive nanohybrids for cancer synergistic therapy.