bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rotationally specific mode–to–mode vibrational energy transfer in D2CO/D2CO collisions. II. Kinetics and modeling
Authors: Bewick C. P. , Martins J. F. , Orr B. J. 
Published: July 2002

Time-resolved infrared-ultraviolet double resonance (IRUVDR) spectroscopy is used to study the kinetics of collision-induced rovibrational energy transfer between the ν6 and ν4 modes of D2CO in the vapor phase. As in paper I [J. Chem. Phys. 93, 8634 (1990)] of the series, attention rests on the existence of V–V transfer channels which are rotationally specific with respect to both J and Ka. Infrared excitation by the 10R(32) CO2 -laser line prepares D2CO in two discrete rovibrational states, (J,Ka,Kc)=(11,4,7) and (7,2,6), of the v6=1 vibrational manifold. D2CO/D2CO collisions then disperse this selected population to various states of the (ν4,ν6) rovibrational manifold, through a combination of rotational energy transfer (RET) and ν6→ν4 transfer. This yields an extensive range of (J,Ka) -resolved IRUVDR kinetic curves, demonstrating the collision-induced evolution of rovibrational population and enabling that evolution to be modeled by means of a master-equation approach.
The features of the model of best fit are as follows: the dominant Ka -resolved channel of ν6→ν4 transfer is that with Ka=4→6; accompanying J-resolved ν6→ν4 transfer channels favor ΔJ=0, with state–to–state rate constants scaling as J3.4; additional (J,Ka) -resolved ν6→ν4 channels allow a spread of J- and Ka -changing V–V transfer. These features are consistent with the accepted mechanism of ν6→ν4 transfer in D2CO, involving enhancement by a combination of Coriolis coupling and rotor asymmetry perturbations. In addition to ν6→ν4 transfer, RET provides the predominant channels of collision-induced relaxation: J-changing RET is described by a conventional fitting law based on the energy gap ‖ΔE‖ for the state-selected molecule; Ka -changing RET favors even values of ΔKa and, contrary to previous expectations, is J selective with a propensity for ΔJ=0. The physical implications of these results are discussed.
Nested interaction representations in time dependent quantum mechanics
Authors: Tannor David J. , Besprozvannaya Anna , Williams Carl J. 
Published: July 2002

Two significant developments in the formulation of the equations of motion in the interaction representation (IR) are introduced in this paper. These developments have direct bearing on the efficient propagation in the interaction representation. The first of these developments involves the concept of sequential, or ‘‘nested’’ interaction transformations on the Hamiltonian and the wave function. Two such nested IRs are described. The first is a momentum- or ‘‘P-adapted’’ IR which, in addition to removing wave packet spreading, systematically maintains the average momentum 〈P〉 at zero. This facilitates a grid which not only has a minimal range, but whose points are maximally sparse. Evaluating the Hamiltonian operator in the P-adapted interaction representation involves only one simple algorithmic modification to the ordinary IR: replacing eiH0t/ℏV(R)e−iH0t /ℏ→eiH0t/ℏV(R+〈P〉t/m) eiH0t/ℏ, i.e., using the potential energy function which is downstream from the wave function by the classical propagation distance. A PR-adapted IR is also defined, which systematically maintains both the average position 〈R〉 and momentum 〈P〉 at zero.
The PR-adapted IR also involves only one modification to the ordinary IR: replacing eiH0t/ℏV(R)e−iH0t /ℏ→eiH0t/ℏV(R+〈R〉 +〈P〉t/m)eiH0t/ℏ. The second formal development consists of the application of the operator equation eiH0t/ℏV(R)e−iH0t /ℏ=V(R+Pt/m) in conjunction with the nested IRs. This formal identity, which is essentially the Heisenberg representation for V(R), provides a convenient route to propagation in the interaction representation without reconstructing the Schrödinger wave function as an intermediate. The time propagation in all representations is performed using an iterative Lanczos reduction scheme combined with a second- order Magnus expansion. Numerical results for the exponential and the 1/R potential are presented, and illustrate that the new representations can easily lead to a savings of an order of magnitude in the size of the grid required for the propagation.
Critical behavior in a binary polymer blend as studied by static and dynamic light scattering
Authors: Meier G. , Momper B. , Fischer E. W. 
Published: July 2002

We report static and dynamic light scattering experiments of an almost symmetric polymer mixture made up from poly(dimethylsiloxane) (PDMS), N=260, and poly(ethylmethylsiloxane) (PEMS), N=340, with N being the degree of polymerization, both below the entanglement molecular weights. The mixture exhibits an upper critical solution temperature Tc≂57 °C. The measurements were performed at the critical composition φc,PEMS = 0.465 in a broad temperature range in the one phase region above the spinodal point. The main results for the static case are: the temperature dependence of the static structure factor S(q=0) can be described by a mean field behavior. For T close to Tc, a crossover to an Ising behavior is observed according to a modified Ginzburg criterion. From the angular dependence of S(q), the static correlation length ξ is determined via an Ornstein–Zernike plot. Our experimentally determined values for limT→∞S(0) and limT→∞ ξ, respectively, are in agreement with theoretical predictions. For the dynamic case, the main results are summarized as follows: as expected, the mutual diffusion coefficient D̃, accessible by quasielastic light scattering, shows a critical slowing down for T→Tc.
For qξ≥1, we observe that the q scaling of the Rayleigh linewidth Γ changes from a q2 to a q3 behavior, which is in agreement with mode coupled expressions. This occurs in a relatively broad temperature range, due mainly to the fact that polymer mixtures exhibit a larger ξ0 ∝√N, on the contrary to any other systems known, which allows us therefore to reach the region qξ≥1 even with light scattering easily. From the separation of the measured Rayleigh linewidth into a critical part and a background part, we have estimated the crossover between mode coupled to nonmode coupled dynamics. It is governed by the coil size. The scaling predictions for the critical part and the background part of the linewidth are in agreement with the predictions of the mode coupled theory by Kawasaki and subsequently by Fredrickson. We find that the mode coupled dynamics reaches far into the mean field regime which is not yet understood by theory. Furthermore, we can show that the critical part of the linewidth data is well represented by the Kawasaki shape function including the viscosity correction. Finally, we have estimated a segmental mobility W0∝D̃⋅S(q=0) which can be interpreted being a segmental quantity only down to characteristic lengths ξ(T)≂Rg. For ξ larger than the coil dimensions, W0∝ξ as predicted by mode coupled dynamics.
Structural measurements of hydrogen-bonded van der Waals dimers and trimers by rotational coherence spectroscopy: 2,5-diphenyloxadiazole with argon, methane, water, and alcohols
Authors: Troxler Thomas , Smith Philip G. , Stratton John R. , Topp Michael R. 
Published: July 2002

Picosecond time-resolved polarized fluorescence experiments involving time-correlated single-photon counting have studied rotational coherence phenomena of hydrogen-bonded and other molecular aggregates in their lowest excited singlet states. The experiments are supported by detailed simulations. Using the molecule 2,5-diphenyl-1,3,4-oxadiazole (PPD) as a host species, experiments have compared van der Waals aggregates with Ar1,2, (CH4)1,2, (H2O)1,2, (CH3OH)1,2, (C2H5OH)1, and (1-C3H7OH)1. Bare PPD, and the argon and methane aggregates all exhibit prominent J-type recurrences. The resulting sums of rotational constants (B+C) are consistent with center-of-mass-bound, three-dimensional structures, having out-of-plane distances for the attached species of 3.3–3.5 Å. The 1:2 aggregates involving argon and methane exhibit additive spectral shifts and nearly additive rotational recurrence times. This shows that the sites for addition of consecutive species are equivalent.
Calculations of rotational constants confirm these findings. All except the Ar 1:2 cluster exist close to the prolate symmetric top limit. On the other hand, the excitation spectra of complexes involving hydrogen-bonding species all show small complexation shifts at the 1:1 level and disproportionately larger shifts at the 1:2 level. Similar nonadditive behavior is seen for the rotational recurrence transients. Hydrogen-bonded species differ from the nonpolar cases, since they show both prominent C-type and J-type transients. This shows that these species all differ significantly from prolate symmetric tops. Detailed simulations reveal that all of the hydrogen-bonding species produce aggregates that involve a single hydrogen bond to one of the PPD nitrogen atoms. This imposes a planar type of structure on the 1:1 water and methanol complexes. On the other hand, the aggregates methanol 1:2, ethanol 1:1, and propanol 1:1 all involve a distinct out-of-plane twist, consistent with the increasing influence of dispersive interactions.
Hydrogen bond distances (N...H–O) are found to be in the range 2.7–2.9 Å, and the hydrogen-bond angles (N–N...H–O), relative to the PPD long axis, range from 115° to 130°. In addition, the water and methanol 1:2 aggregates both contain hydrogen-bonded dimer units that resemble the free dimers of each species as identified by infrared and microwave techniques. For example, we find the (O...H–O) distance in the methanol dimer complex to be ≊2.7 Å.
Hyperfine structure in high spin multiplicity electronic states: Analysis of the B 4Π–X 4Σ− transition of gaseous NbO
Authors: Adam A. G. , Azuma Y. , Barry J. A. , Merer A. J. , Sassenberg U. , Schröder J. O. , Cheval G. , Féménias J. L. 
Published: July 2002

The (0,0) band of the B 4Π–X 4Σ− transition of NbO, near 6600 Å, has been analyzed from spectra taken at sub-Doppler resolution. The transition is notable for the great width of its Nb nuclear hyperfine structure, which is caused principally by the unpaired 5sσ electron in the ground state interacting with the large magnetic moment of the 4193Nb nucleus (I=9/2). A fit to the ground-state combination differences, including four very precise microwave lines measured by Suenram et al. [J. Mol. Spectrosc. 148, 114 (1991)], has given a comprehensive set of rotational, spin, and hyperfine parameters. Prominent among these are the third-order spin–orbit distortions of the spin-rotation interaction and the Fermi contact interaction, which are large and well determined, reflecting different degrees of spin–orbit contamination of the the 4Σ1/2− and 4Σ3/2− components of the ground state.
The δ 2π B 4Π state was hard to fit, for a number of reasons. First, its spin–orbit structure is asymmetric, because of strong perturbations by a 2Π state which has been identified in this work, from among the various weak bands in the NbO spectrum near 7000 Å; the result is that many high order centrifugal distortion terms are needed in an effective Hamiltonian model for the rotation. Second, the hyperfine structure is perturbed, not only by this 2Π state, but by distant Σ and Δ states at higher energy. The δ 2σ* C 4Σ− state at 21 350 cm−1 appears to be one of these. The distant states generate large apparent nuclear spin-rotation interactions, both within and between the Λ components of the Π state, as a result of cross terms between matrix elements of the operators −2BJ⋅L and aI⋅L. Similar cross terms arising from the operators AL⋅S and aI⋅L produce corrections to the Fermi contact matrix elements and are responsible for the unexpected negative sign of the magnetic hyperfine parameter d. The ‘‘off-diagonal’’ quadrupole parameter e2Qq2 is very large, and causes some of the higher J line shapes of the B–X system to be noticeably asymmetric at Doppler limited resolution; its value is consistent with the electron configuration of the B 4Π state being δ 2π.
The susceptibility of Streptococcus pneumoniae to levofloxacin and other antibiotics
Authors: Keller N. , Smollen G. , Davidson Y. , Barzilai A. , Keren G. , Rubinstein E. 
Published: July 2002

Abstract
The aim of this study was to determine the in-vitro susceptibility of Streptococcus pneumoniae to levofloxacin, ciprofloxacin, sparfloxacin, ofloxacin, amoxycillin, cefepime and cefuroxime. In total, 105 isolates (clinical blood and sputum isolates from 1995–96) were selected from the collection of the Department of Clinical Microbiology of the Chaim Sheba Medical Centre. MICs were determined with an agar dilution method according to NCCLS guidelines. The MIC ranges with the test antibiotics against the pneumococcal isolates were: 0.5 mg/L, levofloxacin; 0.12–0.5 mg/L, sparfloxacin; 0.5–2 mg/L, ciprofloxacin; 0.5–1 mg/L, ofloxacin; &lt;0.03–2 mg/L, amoxycillin; &lt;0.03–2 mg/L, cefepime; &lt;0.03–2 mg/L, cefuroxime. The results indicated that although all isolates were susceptible to all the fluoroquinolone agents except ciprofloxacin, some isolates had reduced susceptibility to amoxycillin, cefepime and cefuroxime. We conclude that all S. pneumoniae isolates tested were susceptible to levofloxacin, ofloxacin and sparfloxacin. However, about 85% were susceptible to amoxycillin and the other β -lactam antibiotics tested.
Cardiac Manifestations of “Long COVID” (Post–COVID-19 Conditions)
Authors: Demeter Stephen L. 
Published: October 2022

Abstract
The Centers for Disease Control has defined long COVID—or post–COVID-19 conditions—as a clinical syndrome reflecting a wide range of new, persistent, or recurring health problems experienced by individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (coronavirus disease 2019 [COVID-19]). What is known is that symptoms in these individuals diminish with time. It is unclear how long it takes to achieve maximum medical improvement. This article addresses the cardiac manifestations (including the pulmonary vascular and peripheral vascular manifestations) of long COVID. Emphasis is placed on recent articles (published in the last year) and issues relating to impairment evaluations.
Target localization and multicircular circumnavigation with bearing‐only measurements
Authors: Chen Ke , Qi Guoqing , Li Yinya , Sheng Andong 
Published: October 2022

SummaryThis article studies the multicircular circumnavigation problem of a stationary target using bearing‐only measurements. The proposed estimator‐based control strategy drives the networked mobile agents to move around an unknown target along different circles with any prescribed inter‐agent angular spacing. The results presented in this article are as follows: First, a new estimator is developed by introducing a linear filter into an estimation algorithm which has been widely used in the existing literature. The novelty of the proposed estimator lies in its enhanced convergence rate. Analytical results show that the exponential convergence rate of the estimator can be adjusted to be arbitrarily high by increasing the estimation gain. Second, a distributed controller is designed such that global exponential convergence of the agents to the desired circular formation can be achieved. Besides, the proposed algorithms guarantee that each agent can keep a safe distance from the target, and high angular velocities of the agents can be avoided even if the circumnavigation radii become small. Finally, several numerical simulations are given to corroborate the theoretical results.
Harm reduction innovation: Abstinence, move over
Authors: De Miranda John 
Published: October 2022

Earlier this year, signs of a growing acceptance of harm reduction practices emerged in Washington, D. C. The Biden administration identified harm reduction as a policy priority and followed up with $30 million in grants to treatment programs to institute limited harm reduction strategies. I term this innovation limited or “harm reduction lite” (see “Treatment and recovery discover harm reduction: Now what?,” ADAW July 18; https://onlinelibrary.wiley.com/doi/10.1002/adaw.33500) because treatment programs can qualify by only conducting community presentations and Narcan distribution. Altering treatment protocols to “meet clients where they are,” including people who do not want to pursue abstinence, is another matter.
Biomimetic Macrophage Membrane and Lipidated Peptide Hybrid Nanovesicles for Atherosclerosis Therapy
Authors: Guo Linmiao , Miao Yunqiu , Wang Ying , Zhang Ying , Zhou Erfen , Wang Jiangyue , Zhao Yanqi , Li Lijun , Wang Aohua , Gan Yong , Zhang Xinxin 
Published: October 2022

AbstractAtherosclerosis is the underlying cause for cardiovascular disease. Current pharmacotherapies are limited by the inadequate targeting and insufficient treatment. Herein, inspired by the interaction of macrophage and lipoprotein as a typical hallmark of atherosclerosis, hybrid nanovesicles (MLP‐NVs) are designed by fusion of anti‐inflammatory M2‐phenotype macrophage membranes and lipidated peptide (DOPE‐pp‐HBSP) to mimic the binding manner of cell‐lipoprotein for atherosclerotic treatment. Through hybridization of M2 macrophage membranes and lipidated peptide film, MLP‐NVs facilitate the inflammatory cell internalization at atherosclerotic site, and sequester the proinflammatory cytokines to suppress local inflammation. Moreover, MLP‐NVs exhibit a matrix metalloprotease 2 (MMP2)‐responsive release of the peptide HBSP in plaques, leading to the restoration of dysfunctional endothelial cells. In the ApoE−/− mice with atherosclerosis, simvastatin‐loaded MLP‐NVs provide comprehensive treatment by inherent inflammation suppression, endothelial repair, and cholesterol efflux capacities, resulting in atherosclerotic plaques regression. Through closely mimicking physiological cues, this biomimetic hybrid nanovesicle platform provides a potential strategy for anti‐atherosclerotic therapy.
An Engineered Paper‐Based 3D Coculture Model of Pancreatic Cancer to Study the Impact of Tissue Architecture and Microenvironmental Gradients on Cell Phenotype
Authors: Cadavid Jose L. , Latour Simon , Nowlan Ferris , Co Ileana L. , Landon‐Brace Natalie , Wouters Bradly G. , Grünwald Barbara T. , Nitz Mark , Jackson Hartland Warren , McGuigan Alison P. 
Published: October 2022

AbstractThe spatial configuration of cells in the tumor microenvironment (TME) affects both cancer and fibroblast cell phenotypes contributing to the clinical challenge of tumor heterogeneity and therapeutic resistance. This is a particular challenge in stroma‐rich pancreatic ductal adenocarcinoma (PDAC). Here, a versatile system is described to study the impact of tissue architecture on cell phenotype using PDAC as a model system. This fully human system encompassing both primary pancreatic stellate cells and primary organoid cells using the TRACER platform to allow the creation of user‐defined TME architectures that have been inferred from clinical PDAC samples and are analyzed by CyTOF to characterize cells extracted from the system. High dimensional characterization using CyTOF demonstrates that tissue architecture leads to distinct hypoxia and proliferation gradients. Furthermore, phenotypic markers for both cell types are also graded in ways that cannot be explained by either hypoxia or coculture alone. This demonstrates the importance of using complex models encompassing cancer cells, stromal cells, and allowing control over architecture to explore the impact of tissue architecture on cell phenotype. It is anticipated that this model will help decipher how tissue architecture and cell interactions regulate cell phenotype and hence cellular and tissue heterogeneity.
Swelling‐Dependent Shape‐Based Transformation of a Human Mesenchymal Stromal Cells‐Laden 4D Bioprinted Construct for Cartilage Tissue Engineering
Authors: Díaz‐Payno Pedro J. , Kalogeropoulou Maria , Muntz Iain , Kingma Esther , Kops Nicole , D'Este Matteo , Koenderink Gijsje H. , Fratila‐Apachitei Lidy E. , van Osch Gerjo J. V. M. , Zadpoor Amir A. 
Published: October 2022

Abstract3D bioprinting is usually implemented on flat surfaces, posing serious limitations in the fabrication of multilayered curved constructs. 4D bioprinting, combining 3D bioprinting with time‐dependent stimuli‐induced transformation, enables the fabrication of shape‐changing constructs. Here, a 4D biofabrication method is reported for cartilage engineering based on the differential swelling of a smart multi‐material system made from two hydrogel‐based materials: hyaluronan and alginate. Two ink formulations are used: tyramine‐functionalized hyaluronan (HAT, high‐swelling) and alginate with HAT (AHAT, low‐swelling). Both inks have similar elastic, shear‐thinning, and printability behavior. The inks are 3D printed into a bilayered scaffold before triggering the shape‐change by using liquid immersion as stimulus. In time (4D), the differential swelling between the two zones leads to the scaffold's self‐bending. Different designs are made to tune the radius of curvature and shape. A bioprinted formulation of AHAT and human bone marrow cells demonstrates high cell viability. After 28 days in chondrogenic medium, the curvature is clearly present while cartilage‐like matrix production is visible on histology. A proof‐of‐concept of the recently emerged technology of 4D bioprinting with a specific application for the design of curved structures potentially mimicking the curvature and multilayer cellular nature of native cartilage is demonstrated.
Atomically Dispersed Dual‐Site Cathode with a Record High Sulfur Mass Loading for High‐Performance Room‐Temperature Sodium–Sulfur Batteries
Authors: Zhang Bin‐Wei , Cao Liuyue , Tang Cheng , Tan Chunhui , Cheng Ningyan , Lai Wei‐Hong , Wang Yun‐Xiao , Cheng Zhen‐Xiang , Dong Juncai , Kong Yuan , Dou Shi‐Xue , Zhao Shenlong 
Published: October 2022

AbstractRoom‐temperature sodium–sulfur (RT‐Na/S) batteries possess high potential for grid‐scale stationary energy storage due to their low cost and high energy density. However, the issues arising from the low S mass loading and poor cycling stability caused by the shuttle effect of polysulfides seriously limit their operating capacity and cycling capability. Herein, sulfur‐doped graphene frameworks supporting atomically dispersed 2H‐MoS2 and Mo1 (S@MoS2‐Mo1/SGF) with a record high sulfur mass loading of 80.9 wt.% are synthesized as an integrated dual active sites cathode for RT‐Na/S batteries. Impressively, the as‐prepared S@MoS2‐Mo1/SGF display unprecedented cyclic stability with a high initial capacity of 1017 mAh g−1 at 0.1 A g−1 and a low‐capacity fading rate of 0.05% per cycle over 1000 cycles. Experimental and computational results including X‐ray absorption spectroscopy, in situ synchrotron X‐ray diffraction and density‐functional theory calculations reveal that atomic‐level Mo in this integrated dual‐active‐site forms a delocalized electron system, which could improve the reactivity of sulfur and reaction reversibility of S and Na, greatly alleviating the shuttle effect. The findings not only provide an effective strategy to fabricate high‐performance dual‐site cathodes, but also deepen the understanding of their enhancement mechanisms at an atomic level.