bluuebunny/crossref_metadata_2025 huggingface dataset:
Caspase activity in newt spermatogonial apoptosis induced by prolactin and cycloheximide
Authors: Yazawa Takashi , Fujimoto Kenta , Yamamoto Takashi , Abé Shin‐Ichi
Published: September 2002

We previously showed in vivo and in vitro, that among the spermatogenic stages of the newt, prolactin (PRL) induces apoptosis specifically in the penultimate stage of secondary spermatogonia. In the current report, we demonstrate in vitro that cycloheximide (CHX), an inhibitor of protein synthesis, induces morphological apoptotic changes similar to those caused by PRL, such as chromatin condensation and apoptotic body formation. Next, we found that Z‐VAD‐fmk, an inhibitor of various caspases, suppressed the apoptosis induced by PRL and CHX, but ICE inhibitor Ac‐YVAD‐CHO or caspase‐3 inhibitor Ac‐DEVD‐CHO did not. As high caspase activity was present in extracts of testes treated with CHX, we suggest that an unidentified caspase induces the morphological changes of apoptosis in newt spermatogonia. Mol. Reprod. Dev. 59:209–214, 2001. © 2001 Wiley‐Liss, Inc.
19F‐MRI of perflubron for measurement of oxygen partial pressure in porcine lungs during partial liquid ventilation
Authors: Laukemper‐Ostendorf Simone , Scholz Alexander , Bürger Katja , Heussel Claus P. , Schmittner Marc , Weiler Norbert , Markstaller Klaus , Eberle Balthasar , Kauczor Hans‐Ulrich , Quintel Michael , Thelen Manfred , Schreiber Wolfgang G.
Published: September 2002

A method for in vivo measurement of oxygen partial pressure (pO2) in porcine lungs during partial liquid ventilation (PLV) with perflubron (PFOB) was developed. A pulse sequence for high‐resolution MRI of the distribution of PFOB in the lung after intratracheal administration was developed as well. Moreover, quantitative measurements of longitudinal relaxation time T1 of 19F resonances for assessment of regional pO2 are described. Due to the need to acquire data during a single expiratory breathhold, only low SNRs were achieved in vivo. Therefore, simulations were performed to investigate the influence of background noise on T1 values calculated from data with low SNR. Based on these simulations, a postprocessing strategy was developed to correct for systematic errors by background noise prior to quantitative analysis. Results of a pilot study in pigs under conditions of PLV are presented. Magn Reson Med 47:82–89, 2002. © 2002 Wiley‐Liss, Inc.
Dynamic changes of ADC, perfusion, and NMR relaxation parameters in transient focal ischemia of rat brain
Authors: van Dorsten F.A. , Olàh L. , Schwindt W. , Grüne M. , Uhlenküken U. , Pillekamp F. , Hossmann K.‐A. , Hoehn M.
Published: September 2002

The potential of multiparametric MRI parameters for differentiating between reversibly and irreversibly damaged brain tissue was investigated in an experimental model of focal brain ischemia in the rat. The middle cerebral artery (MCA) was occluded by intraluminal suture insertion for 60 or 90 min, followed by 4.5 h of reperfusion. The apparent diffusion coefficient (ADC) of brain water, T1 and T2 relaxation times, and CBFi, an MR‐derived index of cerebral perfusion, were repeatedly measured and correlated with the outcome from the ischemic impact. A novel user‐independent approach for segmentation of ADC maps into classes of increasing injury was introduced to define regions of interest (ROIs) in which these parameters were evaluated. MCA occlusion led to a graded decline of ADC, which corresponded with both the severity of flow reduction and an increase in T1 and T2 relaxation times. Removal of the suture led to a triphasic restitution of blood flow consisting of a fast initial rise, a secondary decline, and final normalization. Postischemic reperfusion led to a rise of ADC irrespective of the duration of ischemia. However, the quality of recovery declined with increasing severity of the ischemic impact. Throughout the observation time, T1 and T2 showed a continuous increase, the intensity of which correlated with the severity of ADC decline during ischemia. Particularly with longer ischemia time, elevated T2 in combination with reduced ADC yielded a lower probability of recovery during recirculation, while intraischemic perfusion information contributed less to the prediction of outcome. In conclusion, the combination of MR parameters at the end of ischemia correlated with the probability of tissue recovery but did not permit reliable differentiation between reversibly and irreversibly damaged tissue. Magn Reson Med 47:97–104, 2002. © 2002 Wiley‐Liss, Inc.
RF safety of wires in interventional MRI: Using a safety index
Authors: Yeung Christopher J. , Susil Robert C. , Atalar Ergin
Published: September 2002

With the rapid growth of interventional MRI, radiofrequency (RF) heating at the tips of guidewires, catheters, and other wire‐shaped devices has become an important safety issue. Previous studies have identified some of the variables that affect the relative magnitude of this heating but none could predict the absolute amount of heating to formulate safety margins. This study presents the first theoretical model of wire tip heating that can accurately predict its absolute value, assuming a straight wire, a homogeneous RF coil, and a wire that does not extend out of the tissue. The local specific absorption rate (SAR) amplification from induced currents on insulated and bare wires was calculated using the method of moments. This SAR gain was combined with a semianalytic solution to the bioheat transfer equation to generate a safety index. The safety index (°C/(W/kg)) is a measure of the in vivo temperature change that can occur with the wire in place, normalized to the SAR of the pulse sequence. This index can be used to set limits on the spatial peak SAR of pulse sequences that are used with the interventional wire. For the case of a straight resonant wire in a tissue with very low perfusion, only about 100 mW/kg/°C spatial peak SAR may be used at 1.5 T. But for ≤10‐cm wires with an insulation thickness ≥30% of the wire radius that are placed in well‐perfused tissues, normal operating conditions of 4 W/kg spatial peak SAR are possible at 1.5 T. Further model development to include the influence of inhomogeneous RF, curved wires, and wires that extend out of the sample are required to generate safety indices that are applicable to common clinical situations. We propose a simple way to ensure safety when using an interventional wire: set a limit on the SAR of allowable pulse sequences that is a factor of a safety index below the tolerable temperature increase. Magn Reson Med 47:187–193, 2002. © 2002 Wiley‐Liss, Inc.
Single‐shot T measurement to establish optimum echo time for fMRI: Studies of the visual, motor, and auditory cortices at 3.0 T
Authors: Clare Stuart , Francis Susan , Morris Peter G. , Bowtell Richard
Published: September 2002

The signal change in fMRI is dependent on the echo time and the rate of decay of transverse magnetization. The latter factor may vary across regions of the brain as a result of variations in field homogeneity. Previous measurements of the signal change with echo time have generally employed relatively slow multi‐echo techniques, which may be sensitive to movement and habituation effects. Here a fast T measurement technique, involving the generation of six low‐resolution echo planar images from a single FID, is described, and its use in the evaluation of the optimum echo time for visual, motor, and auditory fMRI experiments at 3.0 T is outlined. Magn Reson Med 45:930–933, 2001. © 2001 Wiley‐Liss, Inc.
Nicotinic synapses formed between chick ciliary ganglion neurons in culture resemble those present on the neurons in vivo
Authors: Chen Min , Pugh Phyllis C. , Margiotta Joseph F.
Published: September 2002

We studied nicotinic synapses between chick ciliary ganglion neurons in culture to learn more about factors influencing their formation and receptor subtype dependence. After 4–8 days in culture, nearly all neurons displayed spontaneous excitatory postsynaptic currents (sEPSCs), which occurred at about 1 Hz. Neurons treated with tetrodotoxin displayed miniature EPSCs (mEPSCs), but these occurred at low frequency (0.1 Hz), indicating that most sEPSCs are actually impulse driven. The sEPSCs could be classified by decay kinetics as fast, slow, or biexponential and, reminiscent of the situation in vivo, were mediated by two major nicotinic acetylcholine receptor (AChR) subtypes. Fast sEPSCs were blocked by α‐bungarotoxin (αBgt), indicating dependence on αBgt‐AChRs, most of which are α7 subunit homopentamers. Slow sEPSCs were unaffected by αBgt, and were blocked instead by the α3/β2‐selective α‐conotoxin‐MII (αCTx‐MII), indicating dependence on α3*‐AChRs, which lack α7 and contain α3 subunits. Biexponential sEPSCs were mediated by both αBgt‐ and α3*‐AChRs because they had fast and slow components qualitatively similar to those comprising simple events, and these were reduced by αBgt and blocked by αCTx‐MII, respectively. Fluorescence labeling experiments revealed both αBgt‐ and α3*‐AChR clusters on neuron somata and neurites. Colabeling with antisynaptic vesicle protein antibody suggested that some α3*‐AChR clusters, and a few αBgt‐AChR clusters are associated with synaptic sites, as is the case in vivo. These findings demonstrate the utility of ciliary ganglion neuron cultures for studying the regulation of nicotinic synapses, and suggest that mixed AChR subtype synapses characteristic of the neurons in vivo can form in the absence of normal inputs or targets. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 265–279, 2001
Sorption and transport of linear alkane hydrocarbons in biaxially oriented polyethylene terephthalate
Authors: Dhoot S. N. , Freeman B. D. , Stewart M. E. , Hill A. J.
Published: September 2002

Equilibrium sorption and uptake kinetics of n‐butane and n‐pentane in uniform, biaxially oriented, semicrystalline polyethylene terephthalate films were examined at 35 °C and for pressures ranging from 0 to approximately 76 cmHg. Sorption isotherms were well described by the dual‐mode sorption model. Sorption kinetics were described either by Fickian diffusion or a two‐stage model incorporating Fickian diffusion at short times and protracted polymer structural relaxation at long times. Diffusion coefficients increased with increasing penetrant concentration. n‐Butane solubility was lower than that of n‐pentane, consistent with the more condensable nature of n‐pentane. However, n‐butane diffusion coefficients were higher than those of n‐pentane. Infinite‐dilution, estimated amorphous phase diffusion and solubility coefficients were well correlated with penetrant critical volume and critical temperature, respectively. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1160–1172, 2001
Structural and mechanical behavior of nylon‐6 films. II. Uniaxial and biaxial drawing
Authors: Penel‐Pierron L. , Séguéla R. , Lefebvre J.‐M. , Miri V. , Depecker C. , Jutigny M. , Pabiot J.
Published: September 2002

The plastic behavior of polyamide‐6 (or nylon‐6) films under uniaxial and biaxial tensile drawing is studied in relation to structural features. Quenched films in the mesomorphic β form are more ductile than films in the predominant stable α form. Films in the major γ crystalline form are intermediate between films in the β and α forms. Under uniaxial drawing, a great part of the β phase undergoes strain‐induced phase change into the α form, involving strain hardening of the material. The β→α phase change is more pronounced above 120 °C because of additional thermal reorganization. The γ form that is thermally stable up to 200 °C also undergoes a strain‐induced phase change above 120 °C, but the reorganization is much less important than for the β phase. Biaxial drawing can only be achieved below 120 °C with quenched films. This is likely due to the high mechanical anisotropy of the H‐bonded sheetlike structure of both the α and γ phases that is suspected to develop catastrophic splitting under a normal stress component, notably above 120 °C because of the collapse of the paraffin‐like van der Waals interactions between the sheets. The disordered distribution of the H bonds in the mesomorphic β structure of the quenched films is more appropriate for biaxial drawing. The strain‐induced β→α phase reorganization, which might have been a serious prejudice, proved to be much reduced during biaxial drawing below 120 °C. The mechanism of the strain‐induced phase change is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1224–1236, 2001
Toxicological screening of urine for drugs by liquid chromatography/time‐of‐flight mass spectrometry with automated target library search based on elemental formulas
Authors: Gergov Merja , Boucher Brian , Ojanperä Ilkka , Vuori Erkki
Published: September 2002

The present study describes a novel approach for utilizing liquid chromatography/time‐of‐flight mass spectrometry (LC/TOFMS) in qualitative screening analysis. An LC/TOFMS method was developed for screening toxicologically relevant substances in urine samples. After solid phase extraction and LC separation, the method included full spectrum acquisition followed by automatic internal calibration, searching against a target library, and reporting positive identifications. The target library, containing 433 toxicologically relevant substances in the mass range of 105–734 Da, was created simply by entering the elemental formulas of substances into the instrument software for the calculation of their respective monoisotopic masses. In addition to parent drugs, the library contained selected urinary drug metabolites, based on their structures available in the literature. Identification was based on the exact masses of the compounds. The LC/TOFMS method provided 5–10 ppm mass accuracy for a majority of identified compounds in authentic urine samples. Compared with established thin‐layer and gas chromatographic methods, the LC/TOFMS method produced similar findings in urine with the additional advantage of metabolite identification without actual reference substances. Copyright © 2001 John Wiley & Sons, Ltd.
Analysis of bacterial lipodepsipeptides by matrix‐assisted laser desorption/ionisation time‐of‐flight and high‐performance liquid chromatography with electrospray mass spectrometry
Authors: Monti Simona Maria , Gallo Monica , Ferracane Rosalia , Borrelli Rosa Cinzia , Ritieni Alberto , Greco Maria Luigia , Graniti Antonio , Fogliano Vincenzo
Published: September 2002

Strains of certain plant pathogenic bacteria, in particular several pathovars ofPseudomonas syringae, are known to produce cyclic lipodepsipeptides (LDPs) endowed with peculiar structural features and noticeable biological activities. In this study, a mass spectrometry procedure is proposed for screening LDP‐producing bacterial strains and for identifying and assessing individual LDPs. After matrix‐assisted laser desorption/ionisation time‐of‐flight (MALDI‐TOF) screening of thirteenP. syringaestrains for LDP production, the extracts from culture filtrates of eight positive strains were subjected to electrospray mass spectrometry for the identification of LDPs. Five strains were found to produce two forms of syringomycins (SR‐E and SR‐G) and two forms of syringopeptin 25 (SP25Aand SP25B); two strains produced SR‐E, SR‐G and a new form of SP22; one strain produced syringotoxin (ST) and syringostatin A (SS‐A) in addition to SP25Aand SP25B. The yield in culture of two major LPDs: SR‐G (3.2–13.8 mg L−1) and SP25A(41.6–231.5 mg L−1) was assessed by and high‐performance liquid chromatography with electrospray mass spectrometry (HPLC/ESI‐MS) in both scan and single ion monitoring (SIM) modes. Results of this investigation showed that the mass spectrometry protocol developed here is a precise and reliable method for screening bacterial strains for LDP production and for assessing the amount of each metabolite under various culture conditions. This could be of practical value in view of potential applications, e.g. biocontrol of post‐harvest fungal diseases. Copyright © 2001 John Wiley & Sons, Ltd.
Studies on the association of 2‐thiazolidinecarboxylic acid and antimony potassium tartrate: chiral recognition and prediction of absolute configuration by electrospray ionization mass spectrometry
Authors: Arakawa Ryuichi , Kobayashi Mako , Fukuo Tsuyoshi , Shiraiwa Tadashi
Published: September 2002

Optically active 2‐thiazolidinecarboxylic acid (2‐THC), a substrate for D‐amino acid oxidase in animal kidney, is known to undergo racemization quickly in solution. The association of (+)‐ and (−)‐2‐THC with antimony potassium tartrate K2[Sb2(L or D‐tart)2] was studied by electrospray ionization mass spectrometry (ESI‐MS). We observed that relative intensities of associated ions in acetonitrile/water solution were changing as the racemization progressed. For [Sb2(L‐tart)2]2−, the intensities of the associated ions increased as (+)‐2‐THC underwent racemization to a (−)‐isomer; on the other hand, the intensity of the associated ion decreased as (−)‐2‐THC underwent racemization to a (+)‐isomer. In the case of [Sb2(D‐tart)2]2−, an opposite effect on the intensities of the associated ions was observed. The change in the intensities of associated ions can be used for chiral recognition of (+)‐2‐THC and (−)‐2THC. Stereochemical models of the association of the optical isomers with [Sb2(L‐ or D‐tart)2]2− were constructed from the consideration of both hydrogen bonding of NH‐O functions and HSAB (hard and soft acids and bases) interaction of S and Sb atoms. Comparison of the stereochemical models with the ESI‐MS results enabled us to predict the absolute configurations of the 2‐THC isomers. Copyright © 2001 John Wiley & Sons, Ltd.
Interdiffusion coefficients and conductivity in gold/nickel bilayer thin films on silicon(111) wafers
Authors: Abdul‐Lettif A. M. , Rammo N. N. , Makadsi M. N.
Published: September 2002

Interdiffusion in the gold/nickel bilayer thin films deposited on silicon(111) wafers in the temperature range 200–500 °C has been studied using x‐ray photoelectron spectroscopy (XPS), sheet resistance measurements (SRM) and x‐ray diffraction. Two independent methods have been used to determine the diffusion coefficients: the accumulation concentration of nickel on the gold surface using XPS; and the variation of sheet resistance as a function of annealing time and temperature.

The diffusion coefficients deduced from XPS and SRM are (4.0 × 10−11 cm2 s−1) exp(−0.79 eV/kT) and (4.8 × 10−11 cm2 s−1) exp(−0.83 eV/kT), respectively. It is shown that diffusion of nickel through the gold layer causes a considerable loss in conductivity of the bilayer thin films. Copyright © 2001 John Wiley & Sons, Ltd.
SIMS quantification of Si1−xGex alloys using polyatomic secondary ions
Authors: Dong Gui , Liangzhen Cha , Rong Liu , Wee A. T. S.
Published: September 2002

The matrix effect in Si1−xGex alloys (x ≤ 0.5) grown by ultrahigh vacuum chemical vapour deposition was investigated with an O2+ primary beam in a Cameca IMS 6f instrument. The results showed that the matrix effect in Si1−xGex alloys was significant when the Ge fraction was >0.25, and it turned out to be more pronounced at low impact energies. Nevertheless, the composition of Si1−xGex alloys could be quantified based on the linear variation of appropriate secondary ion intensity ratios against the Ge concentration. The use of polyatomic secondary ions to measure the composition of SiGe alloys is reported in this paper. By this method, both the dopant and matrix elements in a Si/Si1−xGex/Si heterojunction bipolar transistor sample have been quantified by SIMS. The germanium fractions thus determined agree well with values obtained by double‐crystal x‐ray diffraction. Copyright © 2001 John Wiley & Sons, Ltd.
FTIR mechanistic studies on the selective catalytic reduction of NOx by methane and ethane over supported cobalt catalysts
Authors: Hadjiivanov K. , Tsyntsarski B. , Ivanova E. , Klissurski D. , Marinova Ts.
Published: September 2002

The NOx species formed after NO adsorption and NO+O2 co‐adsorption on Co‐ZSM‐5, CoY, Co/SiO2 (high cobalt dispersion) and Co/SiO2 (low cobalt dispersion) were studied by means of IR spectroscopy. It was found that NO adsorption on all samples leads to the formation of Co2+(NO)2 species, which are stable on Co‐ZSM‐5 and CoY but are destroyed during evacuation on Co/SiO2. The stable species produced upon NO+O2 co‐adsorption are different kinds of surface NOx− anionic species. The principal compounds formed on Co‐ZSM‐5 and Co/SiO2 with a high cobalt dispersion are surface monodentate nitrates, characterized by an IR band at ∼1535 cm−1. These nitrates are thermally stable but easily interact with hydrocarbons which confirms that they are key species in selective catalytic reduction (SCR). No monodentane nitrates are formed on CoY and Co/SiO2 with a low cobalt dispersion, which accounts for the low SCR activity reported for such samples. Copyright © 2001 John Wiley & Sons, Ltd.
Two‐dimensional crystallization of nitrobenzene on a monolayer of stearic acid characterized by scanning tunnelling microscopy
Authors: Lei S. B. , Wang C. , Yin S. X. , Xu Q. M. , Bai C. L.
Published: September 2002

Using a monolayer of stearic acid molecules as a buffer layer, nitrobenzene has been immobilized on highly oriented pyrolytic graphite (HOPG) and imaged by scanning tunnelling microscopy (STM) with submolecular resolution. The results indicate that the image contrast is determined by the lowest unoccupied molecular orbital (LUMO) whether a positive or negative bias is applied. This strategy can be used as a general method to characterize small organic molecules by STM under ambient conditions. Copyright © 2001 John Wiley & Sons, Ltd.
Electron inelastic mean free paths (IMFPs) in binary Au–Cu alloys determined by elastic peak electron spectroscopy
Authors: Krawczyk M. , Zommer L. , Jablonski A. , Robert C. , Pavluch J. , Bideux L. , Gruzza B.
Published: September 2002

Numerous data on the inelastic mean free path (IMFP) of electrons have been published, mainly for elemental solids and some inorganic and organic compounds. However, there is limited information available for IMFP values of binary alloy systems. Although IMFP values for different energies can be calculated for alloys from predictive formulae, IMFPs can be measured experimentally by elastic peak electron spectroscopy (EPES). In the present work, the IMFPs for three Au–Cu alloys — Au (25 at.%)–Cu (75 at.%), Au (50 at.%)–Cu (50 at.%), Au (75 at.%)–Cu (25 at.%) — were determined for the first time. The EPES experiments have been performed in three laboratories using spectrometers with different geometries and energy resolutions. The experiments were performed with the use of an Au standard (relative measurements) and without a standard material (absolute measurements). Two Monte Carlo algorithms were used to calculate the IMFPs. The IMFP energy dependence for the alloy samples has been obtained in the primary electron energy range 200–2000 eV. The measured IMFPs were compared with IMFPs calculated from two predictive formulae, i.e. the TPP‐2M equation of Tanuma et al. and the G‐1 equation of Gries. The scatter between the measured IMFPs and those calculated from the predictive formulae has been analysed statistically. The root‐mean‐square deviation from IMFP values calculated from the TPP‐2M equation was 1.81–5.97 Å, depending on the alloy surface composition and the particular EPES measurement, and it was smallest for the Au25Cu75 alloy. The mean percentage deviation from the TPP‐2M IMFPs was ∼27%. Copyright © 2001 John Wiley & Sons, Ltd.
Domain configuration and interface structure analysis of sol–gel‐derived PZT ferroelectric thin films
Authors: Liu Dage , Wang Chen , Zhang Hongxi , Li Junwei , Zhao Liancheng , Bai Chunli
Published: September 2002

The domain configuration and interfacial structure of sol–gel‐derived PZT thin films were evaluated using atomic force microscopy and x‐ray photoelectron spectroscopy. Microstructure and ferroelectric property investigation of the PZT thin films under repeated a.c. field suggests that microcracks may be the major cause for ferroelectric fatigue. The intersection of 90° domain walls, where the concentration of stress occurs, is likely to be the origin of microcracks. In addition, the entrapment of defects at domain walls, grain boundaries and/or PZT/electrode interface due to relatively lower potential energy at these sites results in an internal field with a direction opposite to the applied field, which weakens the electric field intensity in the PZT thin films. A fraction of the domains is pinned and finally results in polarization fatigue of the PZT thin films. Copyright © 2001 John Wiley & Sons, Ltd.
Self‐adjusting trees in practice for large text collections
Authors: Williams Hugh E. , Zobel Justin , Heinz Steffen
Published: September 2002

Splay and randomized search trees (RSTs) are self‐balancing binary tree structures with little or no space overhead compared to a standard binary search tree (BST). Both trees are intended for use in applications where node accesses are skewed, for example in gathering the distinct words in a large text collection for index construction. We investigate the efficiency of these trees for such vocabulary accumulation. Surprisingly, unmodified splaying and RSTs are on average around 25% slower than using a standard binary tree. We investigate heuristics to limit splay tree reorganization costs and show their effectiveness in practice. In particular, a periodic rotation scheme improves the speed of splaying by 27%, while other proposed heuristics are less effective. We also report the performance of efficient bit‐wise hashing and red–blacktrees for comparison. Copyright © 2001 John Wiley & Sons, Ltd.
A three‐step matrix method for strategic marketing management
Authors: Jan Yin‐Ching
Published: September 2002

This paper proposes a simple three‐step matrix method to assess the situations in the marketplace. First, an industry perspective matrix is developed to assess the opportunities and threats in the operating environment. Next, a competitive position matrix is constructed, to determine the strength and weakness of the strategic business unit. Then, the two are combined to produce a market situation matrix. Any firm can locate its strategic business unit into these matrices, and thereby assess its current and predicted future position in a given marketplace. This approach is very easy to implement in practice, and provides a clearer assessment of strategic options than any single decision matrix alone.
Participative knowledge production of learning objects for e‐books
Authors: Manuel Dodero Juan , Aedo Ignacio , Díaz Paloma
Published: September 2002

In a distributed learning environment, the development of learning objects is a participative task. We consider learning objects as knowledge pieces, which are subject to the management processes of acquisition, delivery, creation and production. A multiple‐tier architecture for participative knowledge production tasks is introduced, where knowledge‐producing agents are arranged into knowledge domains or marts, and a distributed interaction protocol is used to consolidate knowledge that is produced in a mart. Knowledge consolidated in a given mart can be in turn negotiated in higher‐level foreign marts. The proposed architecture and protocol are applied to coordinate the authoring of open e‐book packages as learning objects by a distributed group of authors.
The effect of global leadership on purchasing process outcomes
Authors: Tomas M. Hult G. , Ferrell O.C. , Schul Patrick L.
Published: September 2002

This study examines the effects of transformational and transactional leadership behaviors on cycle time, customer orientation, and relationship commitment in the purchasing process of a multinational services organization. The focus is on the activities and relationships between the international strategic business units (SBUs) and the corporate buying center leadership of the organization. Based on a sample of 346 SBUs and a series of 11 case studies, the results suggest that frequent and infrequent SBU users differ somewhat in the leadership behaviors preferred as determined by the effects on the three purchasing outcomes. The paper concludes with a discussion of the results and the implications for future research endeavors on global leadership in purchasing.
Evaluation of a Best-Practice Advisory for Primary Aldosteronism Screening
Authors: Charoensri Suranut , Bashaw Linda , Dehmlow Cheryl , Ellies Tammy , Wyckoff Jennifer , Turcu Adina F.
Published: January 2024

Importance

Primary aldosteronism (PA) is a common cause of secondary hypertension and an independent risk factor for cardiovascular morbidity and mortality. Fewer than 2% to 4% of patients at risk are evaluated for PA.

Objective

To develop and evaluate an electronic health record best-practice advisory (BPA) that assists with PA screening.

Design, Setting, and Participants

This prospective quality improvement study was conducted at academic center outpatient clinics. Data analysis was performed between February and June 2023 and included adults with hypertension and at least 1 of the following: 4 or more current antihypertensive medications; hypokalemia; age younger than 35 years; or adrenal nodule(s). Patients previously tested for PA were excluded.

Exposure

A noninterruptive BPA was developed to trigger for PA screening candidates seen in outpatient setting by clinicians who treat hypertension. The BPA included an order set for PA screening and a link to results interpretation guidance.

Main Outcomes and Measures

(1) The number of PA screening candidates identified by the BPA between October 1, 2021, and December 31, 2022; (2) the rates of PA screening; and (3) the BPA use patterns, stratified by physician specialty were assessed.

Results

Over 15 months, the BPA identified 14 603 unique candidates (mean [SD] age, 65.5 [16.9] years; 7300 women [49.9%]; 371 [2.5%] Asian, 2383 [16.3%] Black, and 11 225 [76.9%] White individuals) for PA screening, including 7028 (48.1%) with treatment-resistant hypertension, 6351 (43.5%) with hypokalemia, 1537 (10.5%) younger than 35 years, and 445 (3.1%) with adrenal nodule(s). In total, 2040 patients (14.0%) received orders for PA screening. Of these, 1439 patients (70.5%) completed the recommended screening within the system, and 250 (17.4%) had positive screening results. Most screening orders were placed by internists (40.0%) and family medicine physicians (28.1%). Family practitioners (80.3%) and internists (68.9%) placed most orders via the embedded order set, while specialists placed most orders (83.0%-95.4%) outside the BPA. Patients who received screening were younger and included more women and Black patients than those not screened. The likelihood of screening was higher among patients with obesity and dyslipidemia and lower in those with chronic kidney disease and established cardiovascular complications.

Conclusions and Relevance

The study results suggest that noninterruptive BPAs are potentially promising PA screening-assistance tools, particularly among primary care physicians. Combined with artificial intelligence algorithms that optimize the detection yield, refined BPAs may contribute to personalized hypertension care.
Primary Care Patients’ Perspectives on Health Care Screening for Firearms in a Diverse, Urban Area
Authors: Wilson Madison R. , Smith Nichole A. , Peek Monica E. , Tung Elizabeth L.
Published: January 2024

Importance

Firearm violence is increasingly recognized as a public health issue, but whether physicians should intervene remains politically contested.

Objective

To explore self-described patient perspectives about the appropriateness and acceptability of health care screening for firearms.

Design, Setting, and Participants

This qualitative study recruited 50 adult patients from a primary care clinic in Chicago, Illinois, from June 7, 2019, to January 11, 2021, to participate in 1 of 12 one-time qualitative focus groups. Focus group discussions were facilitated using an in-depth, semistructured guide, transcribed verbatim from audio recordings, and analyzed for major themes using a pragmatic approach to basic thematic analysis, which is commonly used in implementation science, between December 12, 2019, and November 29, 2022.

Main Outcomes and Measures

Patient perspectives of health care screening for firearms were evaluated to examine complexities of a practice change goal.

Results

Participants were a median age of 60.0 (IQR, 50.5-66.5) years and predominantly female (37 [74%]; male, 11 [22%]; nonbinary, 1 [2%]; transgender, 1 [2%]) and non-Hispanic Black (42 [84%]; non-Hispanic Asian or Pacific Islander, 2 [4%]; non-Hispanic White, 5 [10%]). Two-thirds (32 [64%]) of participants thought that health care screening for firearms was at least sometimes appropriate, recognizing clear benefits, for instance, among patients at risk for suicide. However, few (2 [4%]) had ever discussed firearms with a physician or other health care professional. Even among those who recognized benefits, several barriers to acceptability were described, especially related to bias, stigma, and increased risk for criminal legal involvement. Other major themes included insufficient time to address firearms during health care visits and doubts about a clinician’s ability to intervene. Facilitators to acceptability included screening strategies that were patient centered, sensitive to racial bias, clinically efficient, and accompanied by tangible resources.

Conclusions and Relevance

Incorporating these findings and emergent themes into clinical practice may guide efforts to make firearm screening more acceptable for patients from historically marginalized communities.
Risk Factors for Severe Maternal Morbidity Among Women Enrolled in Mississippi Medicaid
Authors: Maharjan Shishir , Goswami Swarnali , Rong Yiran , Kirby Terri , Smith Dennis , Brett Catherine X. , Pittman Eric L. , Bhattacharya Kaustuv
Published: January 2024

Importance

Mississippi has one of the highest rates of severe maternal morbidity (SMM) in the US, and SMMs have been reported to be more frequent among Medicaid-insured women. A substantial proportion of pregnant women in Mississippi are covered by Medicaid; hence, there is a need to identify potential risk factors for SMM in this population.

Objective

To examine the associations of health care access and clinical and sociodemographic characteristics with SMM events among Mississippi Medicaid–enrolled women who had a live birth.

Design, Setting, and Participants

A nested case-control study was conducted using 2018 to 2021 Mississippi Medicaid administrative claims database. The study included Medicaid beneficiaries aged 12 to 55 years who had a live birth and were continuously enrolled throughout their pregnancy period and 12 months after delivery. Individuals in the case group had SMM events and were matched to controls on their delivery date using incidence density sampling. Data analysis was performed from June to September 2022.

Exposure

Risk factors examined in the study included sociodemographic factors (age and race), health care access (distance from delivery center, social vulnerability index, and level of maternity care), and clinical factors (maternal comorbidity index, first-trimester pregnancy-related visits, and postpartum care).

Main Outcomes and Measures

The main outcome of the study was an SMM event. Adjusted odds ratio (aORs) and 95% CIs were calculated using conditional logistic regression.

Results

Among 13 485 Mississippi Medicaid–enrolled women (mean [SD] age, 25.0 [5.6] years; 8601 [63.8%] Black; 4419 [32.8%] White; 465 [3.4%] other race [American Indian, Asian, Hispanic, multiracial, and unknown]) who had a live birth, 410 (3.0%) were in the case group (mean [SD] age, 26.8 [6.4] years; 289 [70.5%] Black; 112 [27.3%] White; 9 [2.2%] other race) and 820 were in the matched control group (mean [SD] age, 24.9 [5.7] years; 518 [63.2%] Black; 282 [34.4%] White; 20 [2.4%] other race). Black individuals (aOR, 1.44; 95% CI, 1.08-1.93) and those with higher maternal comorbidity index (aOR, 1.27; 95% CI, 1.16-1.40) had higher odds of experiencing SMM compared with White individuals and those with lower maternal comorbidity index, respectively. Likewise, an increase of 100 miles (160 km) in distance between beneficiaries’ residence to the delivery center was associated with higher odds of experiencing SMM (aOR, 1.14; 95% CI, 1.07-1.20).

Conclusions and Relevance

The study findings hold substantial implications for identifying high-risk individuals within Medicaid programs and call for the development of targeted multicomponent, multilevel interventions for improving maternal health outcomes in this highly vulnerable population.
An Updated Equitable Model of Readiness for Transition to Adult Care
Authors: Prussien Kemar V. , Crosby Lori E. , Faust Haley L. , Barakat Lamia P. , Deatrick Janet A. , Smith-Whitley Kim , Schwartz Lisa A.
Published: January 2024

Importance

Despite elevated health risks during young adulthood, many adolescents and young adults with serious health care needs face barriers during the transfer to an adult specialty practitioner, and health disparities may occur during the transition.

Objective

To validate the content of an updated Social-Ecological Model of Adolescent and Young Adult Readiness for Transition to Promote Health Equity (SMART-E) in a group of adolescents and young adults with sickle cell disease (SCD) and their supports.

Design, Setting, and Participants

Health equity framework components were reviewed. Systems of power (eg, institutional and practitioner bias) and environments or networks (eg, peer or school support) were added as SMART-E preexisting factors, and health literacy was included within readiness factors. Adolescents and young adults aged 16 to 29 years with SCD, caregivers, and practitioners participated in this convergent, mixed-methods study within Children’s Hospital of Philadelphia between January and August 2022.

Main Outcomes and Measures

Content validity was assessed through nominations of top 3 most important transition barriers prior to interviews and focus groups, ratings on importance of SMART-E factors (0-4 scale; ratings >2 support validity) after interviews and focus groups, nominations of 3 most important factors for transition and for health equity, and qualitative content analysis of interview transcripts.

Results

The study enrolled 10 pediatric adolescents and young adults (mean [SD] age, 18.6 [2.9] years; 4 female and 6 male), 10 transferred adolescents and young adults (mean [SD] age, 22.9 [2.1] years; 8 female and 2 male), 9 caregivers (mean [SD] age, 49.8 [8.7] years; 5 female and 4 male), and 9 practitioners (mean [SD] age, 45.6 [10.5] years; 8 female and 1 male). Quantitative ratings supported the content validity of SMART-E and met established criteria for validity. Systems of power was the most endorsed transition barrier (14 of 38 participants) reported prior to interviews and focus groups. After the interview, participants endorsed all SMART-E factors as important for transition, with new factors systems of power and environments and networks rated at a mean (SD) 2.8 (1.23) and 3.1 (0.90), respectively, on a 0 to 4 scale of importance. The most important factors for transition and equity varied by participant group, with all factors being endorsed, supporting the comprehensiveness of SMART-E. Qualitative data corroborated quantitative findings, further supporting validity, and minor modifications were made to definitions.

Conclusions and Relevance

SMART-E obtained initial content validation with inclusion of health equity factors for adolescents and young adults with SCD, caregivers, and practitioners. The model should be evaluated in other populations of adolescents and young adults with chronic disease.
Parameters self‐turning controller fused with an adaptive nominal model for disturbance observer: Application to direct drive manipulator with significant payload changes
Authors: Liu Yang , Chen Songlin , Xie Cheng
Published: January 2024

The direct drive manipulator, which directly links the joint shaft to the motor rotor, is susceptible to external disturbances and model perturbations. When the direct drive manipulator operates with varying payloads, the disturbance observer (DOB) with a constant nominal model struggles to achieve satisfactory performance. To minimize estimation errors caused by disturbance, enhance trajectory tracking accuracy, and improve system robustness, this article proposes a controller parameter self‐tuning strategy with settling time, fused with a nominal model adaptive disturbance observer. Specifically, by optimizing the gain coefficient of the model reference adaptive identification (MRAI), the significant changes in payload at the manipulator's end joint can be quickly and accurately estimated. The inertia introduced by the payload is then employed to continuously update the nominal model of the manipulator, incorporating information about the inertia of the coupling joints. In addition, the controller parameters are updated using a self‐tuning link with settling time, which guarantees that the closed‐loop characteristics of the system remain unaffected by payload changes. Finally, the proposed method was validated using a two‐joint direct drive manipulator. The results demonstrate the robustness of the proposed method in the presence of significant payload changes, and the accuracy of disturbance estimation and the tracking performance of the proposed control strategy is significantly improved.
Nanocellulose‐Based Ink for Vertically 3D Printing Micro‐Architectures with High‐Resolution
Authors: Shi Ge , Tian Miao , Chen Yutong , Zhong Linxin , Zhang Wenli , Chen Zehong , Sun Shirong , Xia Ruidong , Iwuoha Emmanuel I. , Peng Xinwen
Published: January 2024

Nanocellulose has become an important renewable component for composite inks, owing to its desirable physical properties, reinforcing capabilities, and tunable self‐assembly behavior. However, it is difficult to improve the rheological performance of the nanocellulose‐based composite to meet the requirement for 3D printing high resolution microarchitectures. Herein, a strategy is proposed that incorporation of amphiphilic molecular surfactant into nanocellulose gel can increase the molecular interaction via hydrophobic bonds and enhance the ink viscoelasticity. Following the design, a composite ink is formulated by adding xylan and Nonaethylene glycol monododecyl ether (C12E9) within nanocellulose gel. A new printing program is designed to achieve vertical writing of the composite ink and obtain free‐standing micropillars and microhemispheres with high resolution in dozens of micrometers. The microhemisphere on an atomic force microscope (AFM) cantilever can be used as colloidal probe. This work proves that nanocellulose composite ink is a candidate for 3D printing functional devices with special microstructures.
A Multistage‐Responsive Antibody‐Delivery Strategy to Improve Immunotherapy for NSCLC Brain Metastasis by Ultrasensitive Releasing and Tumor‐Anchoring
Authors: Li Shuaijun , Meng Caiting , Hao Qian , Dai Luyao , Shi Jiahong , Xu Ji , Zhou Xin , Zhao Sitong , Yang Jinfan , Kang Huafeng , Hou Yuzhu , Zhang Mingzhen , Ma Xiaobin , Tan Mingqian , Wu Hao
Published: January 2024

Immune checkpoint blockade (ICB) therapy has emerged as a promising approach in clinical oncology. For brain metastases, the presence of the robust blood–brain barrier (BBB) and potential immune‐related adverse events (irAEs) pose significant challenges. Here, a multistage‐responsive antibody‐delivery strategy is developed for non‐small cell lung cancer (NSCLC) brain metastases, with the ultra‐pH sensitivity borate bonds. The antibody‐delivery nanoformulation (MB‐aPDL1) is able to maintain the “silent state” in health tissue, cross the BBB/BTB by the GLUT1‐mediated transcytosis, release the functionalized aPDL1 responsively, and promote the aPDL1 tumor‐anchoring. In the in vivo tumor region, the MB‐aPDL1 rapidly releases the activated BPA6‐aPDL1, which successfully anchors to the tumor cells and improves the efficiency of ICB therapy. The two in vivo ICB therapy studies show a significant tumor growth inhibition from the MB‐aPDL1 with an encouraging cure rate of 20% for the NSCLC brain metastases, due to enhanced immune response in tumor, commendably with less behavioral adverse reactions and liver damage. Taken together, this antibody‐delivery strategy holds substantial potential for application in clinical treatment of brain metastases.
A Rooted Multifunctional Heterogeneous Interphase Layer Enabled by Surface‐Reconstruction for Highly Durable Sodium Metal Anodes
Authors: Cao Liang , Guo Jia , Feng Yong , Li Yue , Qiu Yawen , Zhu Wenxuan , Tan Yajun , Sun Chencheng , Rui Xianhong , Geng Hongbo
Published: January 2024

Sodium plating–stripping with high reversibility is still an intractable challenge for sodium metal‐based batteries due to the fragile natural solid‐electrolyte interphase (SEI) film and severe Na dendrites growth. Herein, a surface reconstruction strategy is proposed and a rooted heterogeneous interlayer derived from in situ reactions between tin selenide and Na metal (abbr. Na/SnSe) is produced to regulate Na+ deposition behavior and impede dendrite growth. The high sodiophilic Na15Sn4 component demonstrates the robust combination and dendrite suppression capability, inhibiting fracture and delamination problems during volume variation. Meanwhile, the superionic Na2Se ingredient contributes to the optimized Na+ conduction efficiency and low nucleation overpotential, enabling uniform distribution of electrical fields and ultimately eliminating Na dendrites. Consequently, the reconfigured multifunctional Na/SnSe interphase realizes a long‐term lifespan over 2400 h at 0.5 mA cm−2/1 mAh cm−2 in symmetric cell with an extremely low voltage hysteresis. Moreover, the assembled Na/SnSe||NaNi1/3Fe1/3Mn1/3O2 pouch cell achieves exceptional cycling stability and capacity retention (90.4 mAh g−1 after 1800 cycles at a high current density of 2 A g−1), exploiting an avenue for designing durable SEI layer and high‐quality sodium metal batteries.
Regulating Interfacial Ion Adsorption for Smooth and Durable Zinc Cycling at High Area Capacity
Authors: Long Tao , Zhao Qing‐Yuan , Yin Guang‐Yuan , Xie Peng‐Xing , Liu Suli , Ma Xin , Wu Qing , Lu Bing‐Yi , Dai Zhihui , Zeng Xian‐Xiang
Published: January 2024

Reversible and dendrite‐free zinc (Zn) circulation is essential for longevous aqueous zinc‐ion batteries (ZIBs) and greatly impacted by the property of Zn interface and electrolyte, especially when confronted with high current density and large area capacity. Herein, a hierarchical Zn interface is constructed by the preferential anion surfactant adsorption and reaction, and assists to reduce the interfacial energy and side reactions for enhanced diffusion kinetics and reversibility during Zn plating/stripping. Thus, highly reversible and smooth Zn anodes are achieved with a long‐term stability of 5500 h at 1 mA cm−2/1 mAh cm−2, an impressive rate up to 40 mA cm−2 for 10 mAh cm−2 and a large cumulative plating capacity of 4.45 Ah cm−2 at 10 mA cm−2 in Zn symmetric cells. Even under a high depth of discharge of 60% (5.85/7.65 mAh cm−2), Zn symmetric batteries can still maintain ca. 800 h's life. The proposed countermeasure has also proved to be valid in prolonging the lifespan and stability of Zn‐MnO2 full batteries at both low and high cycling current densities.