bluuebunny/crossref_metadata_2025 huggingface dataset:
A rare cause of stroke after transcatheter aortic valve replacement: Retained foreign body
Authors: Nanjudappa Aravinda , Bhagat Abhishek , Bates Mark C.
Published: June 2019

The field of transcatheter aortic valve replacement (TAVR) has matured significantly with the outcome and durability data now supporting use in lower‐risk patients. We present a preventable complication from early in our experience (5 years ago) that illustrates the importance of heart team communication and cautious multidiscipline cross‐pollination during the formative years of a program. An 87‐year old female developed confusion, slurred speech and left upper extremity weakness 1 day following TAVR with inconclusive findings on carotid artery duplex and transthoracic echocardiography. Subsequent CT‐scan disclosed a linear, ring‐like, structure in the ascending aorta. The foreign body (FB) was radiolucent and successfully snared via tactile sensation and anatomic landmarks informed by the CT. The extricated FB was the valvuloplasty balloon guard (BG) that was inadvertently introduced into the patient via ascending aortic large sheath access. The failure mode was traced back to the first time use of a new balloon system and unrecognized BG by the surgical physician and technician components of the Heart Team who took the lead role in device insertion due to the open chest access. Subsequently, the heart team made changes to mitigate similar future complications by sharing multidiscipline responsibility for all procedural steps and ensuring the use of all new adjuvant devices are preceded by a procedural pause and team consensus regarding device preparation and use. Additionally, the manufacturer addition of a radiopaque marker or flair on the valvuloplasty BG may be warranted.
Colonic and perianal ulceration exhibiting vacuolar interface dermatitis in the setting of HIV
Authors: Tadros Joseph , Chastain Cody A. , Tkaczyk Eric
Published: June 2019

We report a case of noninfectious vacuolar interface dermatitis associated with colonic and perianal ulceration in a patient with acquired immunodeficiency syndrome (AIDS), which responded to immunosuppressive treatment. Our findings suggest that interface dermatitis in the setting of AIDS may warrant further gastrointestinal evaluation and may respond to immunosuppression.
Evaluate, boost your executive presence quotient
Authors: McCarthy Claudine
Published: June 2019

BOSTON — If you question why you've been overlooked for promotions and job offers, it likely has something to do with your executive presence. But you can evaluate your executive presence and take concrete steps to boost it. That's according to Caitlin Houlihan, associate director of student involvement, and Mario Rapetti, assistant dean of student life, both in the Office of Community Engagement at Purchase College, who presented on the book Executive Presence by Sylvia Ann Hewlett, at the annual conference for ACPA — College Student Educators International.
Gender‐based differential item functioning in measures of eating pathology
Authors: Schaefer Lauren M. , Anderson Lisa M. , Simone Melissa , O'Connor Shannon M. , Zickgraf Hana , Anderson Drew A. , Rodgers Rachel F. , Thompson J. Kevin
Published: June 2019

Objective

Eating disorder (ED) symptoms are common and impairing in males, despite their perception as “female” disorders. As existing self‐report symptom measures were developed and primarily validated in women, there is a need to establish the utility of these measures in men. The present study used differential item functioning (DIF) analyses to explore whether item endorsement differed by gender for three commonly used ED symptom measures.

Method

Participants were undergraduate men (n = 1,083) and women (n = 2,424) from three universities in the United States. Global scores on the Eating Attitudes Test‐26 (EAT‐26), Eating Disorder Examination Questionnaire (EDEQ), and Eating Disorder Diagnostic Scale for DSM‐IV (EDDS) were examined. Tests of DIF were conducted by regressing each item against its composite scale score, and then comparing fit and variance explained (R2) to a model with the interaction of item*gender. The clinical significance threshold for DIF is ΔR2 ≥ 0.13.

Results

There was no evidence of clinically significant DIF within the EAT‐26, EDEQ, or EDDS.

Discussion

Findings suggest that the examined measures perform similarly for undergraduate men and women, supporting their use in nonclinical male samples. However, development and testing of items reflecting ED symptoms that more commonly occur in males (e.g., muscularity‐oriented behaviors) is encouraged.
Relating spatial patterns of stream metabolism to distributions of juveniles salmonids at the river network scale
Authors: Kaylor Matthew J. , White Seth M. , Saunders W. Carl , Warren Dana R.
Published: June 2019

Understanding the factors that drive spatial patterns in stream ecosystem processes and the distribution of aquatic biota is important to effective management of these systems and the conservation of biota at the network scale. In this study, we conducted field surveys throughout an extensive river network in NE Oregon that supports diminishing populations of wild salmonids. We collected data on physical habitat, nutrient concentrations, biofilm standing stocks, stream metabolism (gross primary production [GPP] and ecosystem respiration [ER]), and ESA‐listed juvenile salmonid density from approximately 50 sites across two sub‐basins. Our goals were to (1) to evaluate network patterns in these metrics, and (2) determine network‐scale linkages among these metrics, thus providing inference of processes driving observed patterns. Ambient nitrate‐N and phosphate‐P concentrations were low across both sub‐basins (<40 μg/L). Nitrate‐N decreased with watershed area in both sub‐basins, but phosphate‐P only decreased in one sub‐basin. These spatial patterns suggest co‐limitation in one sub‐basin but N limitation in the other; experimental results using nutrient diffusing substrates across both sub‐basins supported these predictions. Solar exposure, temperature, GPP, ER, and GPP:ER increased with watershed area, but biofilm Chl a and ash‐free dry mass (AFDM) did not. Spatial statistical network (SSN) models explained between 70% and 75% of the total variation in biofilm Chl a, AFDM, and GPP, but only 21% of the variation in ER. Temperature and nutrient concentrations were the most supported predictors of Chl a and AFDM standing stocks, but these variables explained little of the total variation compared to spatial autocorrelation. In contrast, solar exposure and temperature were the most supported variables explaining GPP, and these variables explained far more variation than autocorrelation. Solar exposure, temperature, and nutrient concentrations explained almost none of the variation in ER. Juvenile salmonids—a key management focus in these sub‐basins—were most abundant in cool stream sections where rates of GPP were low, suggesting temperature constraints on these species restrict their distribution to oligotrophic areas where energy production at the base of the food web may be limited.
Lithium Pre‐cycling Induced Fast Kinetics of Commercial Sb2S3 Anode for Advanced Sodium Storage
Authors: Fu Lin , Shang Chaoqun , Li Guocheng , Hu Le , Zhang Xuzi , Huang Lanyan , Wang Xin , Zhou Guofu
Published: June 2019

Because of the abundant sodium resources and identical fundamental principles, sodium ion batteries (SIBs) are the state‐of‐the‐art alternative for lithium ion batteries. However, the larger ionic radius of Na+ causes sluggish reaction kinetics, which directly results in inferior electrochemical performance. In this work, the sodium storage properties of commercial bulk Sb2S3 (CSS) were improved by a single lithiation/delithiation cycle obtaining the lithium pre‐cycled Sb2S3 (LSS). Quantitative analysis reveals that the sodiation/desodiation kinetics of CSS and LSS is mainly diffusion‐controlled behavior and capacitive process, respectively. Thus, the reaction kinetics of LSS is promising, which exhibits improved initial coulombic efficiency, stable cycling performance, and high rate capability. In addition, a stable Li‐containing solid electrolyte interphase film was formed during the lithiation process, which can prevent continuous consumption of electrolyte during the each sodiation process. These results demonstrate that prelithiation technique should be a potential strategy to promote practical application for SIBs.
Pain vs. comfort diary: A fully remote app‐based experiment
Authors: Gruszka Piotr , Stammen Christina , Bissantz Nicolai , Jensen Mark P.
Published: June 2019

Background

Focusing on pain while completing a pain diary might have detrimental effects on pain intensity. Inverted comfort ratings might be used instead.

Methods

A fully remote app‐based registered experiment was conducted to investigate the effects of a pain versus comfort diary on 7‐day recall ratings of pain intensity during a 3‐week period. The diary included questions about past, current and expected pain or comfort. Randomization took place by the study app, thereby controlling for effects of experimenter bias.

Results

Contrary to the study hypothesis, multilevel regression showed a more pronounced decrease in 7‐day recall ratings of pain in the group who rated pain intensity daily (n = 184) than in the group who rated comfort daily (n = 205, B = −0.17, p = 0.034). There were no between‐group differences in secondary outcomes (comfort, depressive symptoms, pain interference and happiness). Exploratory analyses revealed more pronounced decreases in pain intensity in participants who experienced less frequent pain in the previous 6 months. Correlations between pain and comfort ratings decreased from −0.39 at baseline to −0.06 after 3 weeks.

Conclusions

The findings do not support the potential beneficial effects of replacing diary ratings of pain intensity with diary ratings of comfort. The unexpected decreases among those who completed daily pain diaries might have been due to the inclusion of questions about expected pain. Decreasing correlations between pain and comfort ratings suggest that comfort ratings are not merely inverted pain ratings; rather, they appear to assess a domain distinct from pain intensity.

Significance

The positive effects of pain diaries on pain trajectories appear to constitute a reliable effect and not a methodological artefact. Pain diaries should be investigated systematically to identify ways to optimize their effects on clinical outcomes. Comfort diaries, however, do not appear to be an efficacious substitute for pain diaries; if the current findings replicate, they indicate that primary care practitioners should continue to use pain diaries in clinical care.
Direct observation of single plasmonic metal nanoparticle reaction in microcolumn with chromatic‐aberration‐free LASER light‐sheet scattering imaging
Authors: Feng Jingjing , Cao Xuan , Pan Qi , He Yan
Published: June 2019

Direct observation and characterization of individual noble metal nanoparticles (MNPs) and their chemical reactions have attracted much attention owing to their unique physical and chemical properties and extensive applications. To achieve high‐throughput information‐rich evaluation of MNPs, it would be advantageous to combine highly efficient microcolumn separation technology with on‐column high resolution plasmonic imaging technique. Here, with a chromatic aberration‐suppressed supercontinuum laser light‐sheet scattering imaging system and colorimetric detection, we monitored oxidation process of single gold nanorods inside a capillary under gravity driven flow, and observed heterogenous reaction intermediates and pathways for different MNP surface modifications. The results suggest that molecular interactions and bindings with MNPs have a significant impact on their reaction kinetics. This high‐throughput on‐line single particle detection technique could be potentially applied to chemical and biochemical reaction studies of other MNPs.
Evaluate, boost your executive presence quotient
Authors: McCarthy Claudine
Published: June 2019

BOSTON — If you find yourself overlooked for promotions and job offers, it likely has something to do with your executive presence. But you can evaluate your executive presence and take concrete steps to give it a boost. That's according to Caitlin Houlihan, associate director of student involvement, and Mario Rapetti, assistant dean of student life, both in the Office of Community Engagement at Purchase College, who presented on the book Executive Presence by Sylvia Ann Hewlett at the annual conference for ACPA — College Student Educators International.
Boost employee morale to provide enhanced services to students
Authors: Gelpi Aileen
Published: June 2019

Andrew Wright joined the University of Southern Indiana in January 2015 as the vice president for enrollment management. He was tasked with leading the university's programs to enhance the recruitment and retention of students. Wright holds a bachelor's degree from Central Michigan University and an MBA from the University of Akron.
The Workplace as a Context for Adult Literacy and Numeracy Learning
Authors: Alkema Anne
Published: June 2019

This department focuses on literacy leaders, including school and instructional leaders, teachers, and external partners, who are working to improve outcomes for adolescent and adult learners in a wide range of education settings. Columns investigate the challenges and complexities inherent in such work and share lessons learned, impactful strategies and approaches, and promising pathways forward.
The Apple and the Acorn: Generating Adolescent Literacy Learners
Authors: Hruby George G.
Published: June 2019

This department explores critical perspectives on issues at the intersection of policy and practice in order to generate fresh questions about enduring dilemmas, new challenges, and debates.
Effects of Divalent Salts on the Interfacial Activity of the Mixed Surfactants at the Water/Model Oil Interface
Authors: Lv Kaihe , Jia Kaile , Han Yugui , Wang Qiuxia , Leng Xu , Yan Hui , Jia Han
Published: June 2019

In our previous report, the mixed cationic/anionic surfactant system consisting of N‐dodecyl‐N‐methylpyrrolidinium bromide (L12) and sodium dodecyl sulfate (SDS) showed good interfacial tension (IFT) reduction of water/model oil (Vtoluene:V
n‐decane = 1:1). In the present study, the effects of divalent salts (MgCl2 or CaCl2) on the interfacial activity were systematically evaluated. The additional Mg2+ ions greatly reduced the IFT to an ultralow value, whereas Ca2+ ions caused the generation of the precipitates and resulted in increased IFT values. The precipitates disappeared in binary divalent salt solutions, and the IFT values remained at a low level. Based on the valence, polarizability, and hydrated radius of the ions, we proposed a model to explain the abnormal changes. The effects of NaCl and temperature were investigated to further verify our proposed mechanism. Moreover, the additional divalent salts obviously enhanced the stability of L12/SDS stabilized emulsions.
Primary odynophonia: When pain is out of proportion to dysphonia
Authors: Kim Se‐in , Atkinson Cory , Harris Amy Hamilton , Tibbetts Kathleen , Mau Ted
Published: June 2019

Objectives/Hypothesis

Odynophonia is generally regarded as a symptom of a voice disorder. However, a subset of patients with odynophonia have debilitating pain out of proportion to the relatively mild degree of dysphonia and are not responsive to voice therapy. The goals of this study were to 1) describe the symptomatology of this subset of patients and differentiate it from typical odynophonia, 2) propose alternate models to explain this phenomenon of primary odynophonia, and 3) present a new treatment paradigm based on the proposed models.

Study Design

Case series.

Methods

Inclusion criteria were complaint of persistent pain associated with voicing, normal vocal fold mobility, complete glottic closure, and limited or lack of response of pain to voice therapy. Presenting symptoms, voice evaluation, and treatment outcomes were reviewed.

Results

Eleven patients fit the inclusion criteria. The degree of pain did not follow the trajectory of vocal improvement with therapy. The pain was stagnant or worsened with voice exercises. The most dramatic improvement came about in one patient who received false vocal fold Botox injections, and another who received thyrohyoid lidocaine/triamcinolone injection. We propose that these patients had developed primary odynophonia, in which the pain had become self‐sustaining and no longer responded to correction of hyperfunctional vocal behavior. The mechanism of pain persistence may involve superior laryngeal neuralgia, cartilaginous or ligamentous inflammation, and/or central sensitization.

Conclusions

A minority of patients have primary odynophonia distinct from typical odynophonia. Direct treatment of pain may be advisable prior to or in conjunction with voice therapy.

Level of Evidence

4

Laryngoscope, 130:E183–E189, 2020
Coupling analysis of ambient wave to the shielded cavity with penetrated wire using a time domain hybrid method
Authors: Ye Zhihong , Zhou Jianjian , Gou Dan , Zhang Jie
Published: June 2019

Due to the numerical methods used for the coupling analysis of the shielded cavity with penetrated wire excited by ambient wave are lack, an efficient time domain hybrid method is presented in this article, which consists of thin wire finite difference time domain (FDTD) method and hybrid FDTD and transmission line equations method (called FDTD‐TL method). In this method, the penetrated wire is decomposed into external and internal transmission lines according to the enclosure structure of the shielded cavity firstly. Then the thin wire FDTD method is applied to calculate the currents on the external transmission line, which are enforced as the boundary of the internal transmission line naturally. Meanwhile the FDTD‐TL method is used to build the coupling model of ambient wave to the internal transmission line to obtain the voltage and current responses on the terminal load of internal line. This method has one prominent advantage is that it can realize the cooperative calculations of electromagnetic field radiation and the coupling responses on the penetrated wire. Finally, two numerical simulations of ambient wave to one shielded cavity with penetrated wire in the free space and shielded cavity are utilized to verify the accuracy and efficiency of this presented method by comparing with the electromagnetic software CST.
Segment‐averaged LET concept and analytical calculation from microdosimetric quantities in proton radiation therapy
Authors: Bertolet A. , Baratto‐Roldán A. , Cortés‐Giraldo M. A. , Carabe‐Fernandez A.
Published: June 2019

Purpose

This work introduces the concept of segment‐averaged linear energy transfer (LET) as a new approach to average distributions of LET of proton beams based on a revisiting of microdosimetry theory. The concept of segment‐averaged LET is then used to generate an analytical model from Monte Carlo simulations data to perform fast and accurate calculations of LET distributions for proton beams.

Methods and material

The distribution of energy imparted by a proton beam into a representative biological structure or site is influenced by the distributions of (a) LET, (b) segment length, which is the section of the proton track in the site, and (c) energy straggling of the proton beam. The distribution of LET is thus generated by the LET of each component of the beam in the site. However, the situation when the LET of each single proton varies appreciably along its path in the site is not defined. Therefore, a new distribution can be obtained if the particle track segment is decomposed into smaller portions in which LET is roughly constant. We have called “segment distribution” of LET the one generated by the contribution of each portion. The average of that distribution is called segment‐averaged LET. This quantity is obtained in the microdosimetry theory from the average and standard deviation of the distributions of energy imparted to the site, segment length, and energy imparted per collision. All this information is calculated for protons of clinically relevant energies by means of Geant4‐DNA microdosimetric simulations. Finally, a set of analytical functions is proposed for each one of the previous quantities. The presented model functions are fitted to data from Geant4‐DNA simulations for monoenergetic beams from 100 keV to 100 MeV and for spherical sites of 1, 5, and 10 μm in diameter.

Results

The average differences along the considered energy range between calculations based on our analytical models and MC for segment‐averaged dose‐averaged restricted LET are −0.2 ± 0.7 keV/μm for the 1 μm case, 0.0 ± 0.9 keV/μm for the 5 μm case, and −0.3 ± 1.1 keV/μm for the 10 μm case, respectively. All average differences are below the average standard deviation (1σ) of the MC calculations.

Conclusions

A new way of averaging LET for a proton beam is performed to incorporate the effects produced by the variation of stopping power of each individual proton along microscopic biological structures. An analytical model based on MC simulations allows for fast and accurate calculations of segment‐averaged dose‐averaged restricted LET for proton beams, which otherwise would need to be calculated from exhaustive MC simulations of clinical plans.
Automated 4π radiotherapy treatment planning with evolving knowledge‐base
Authors: Landers Angelia , O’Connor Daniel , Ruan Dan , Sheng Ke
Published: June 2019

Purpose

Non‐coplanar 4π radiotherapy generalizes intensity modulated radiation therapy (IMRT) to automate beam geometry selection but requires complicated hyperparameter tuning to attain superior plan quality, which can be tedious and inconsistent. In this study, a fully automated 4π treatment planning was developed using evolving knowledge‐base (EKB) planning guided by dose prediction.

Methods

Twenty 4π lung and twenty 4π head and neck (HN) cases were included. A statistical voxel dose learning model was initially trained on low‐quality plans created using generic hyperparameter templates without manual tuning. To improve the automated plan quality without being limited by the training data quality, a new 4π optimization problem was formulated to include a one‐sided penalty on the organ‐at‐risk (OAR) dose deviation from the predicted dose. This directional OAR penalty encourages superior OAR sparing. The fast iterative shrinkage‐thresholding algorithm (FISTA) was used to solve the large‐scale beam orientation optimization problem. With the improved plans, new predictions were created to guide the next loop of EKB planning for a total of 10 loops. Plan quality was evaluated using a plan quality metric (PQM) points system based on clinical dose constraints and compared with automated planning approaches guided by manual high‐quality plans using all non‐coplanar beams, automated plans using individually evolved targeted dose, and manually created 4π plans.

Results

For the lung cases, the final EKB plans had significantly higher PQM than manually created 4π (+2.60%). The improvements plateaued after the third loop. The final HN EKB plans and manually created 4π plans had comparable PQMs, but had lower PQM compared to automated plans using a high‐quality training set (−3.00% and −4.44%, respectively). The PQM consistently increased up to the sixth loop. Individually evolved plans were able to improve the plan quality from initial condition due to the one‐sided cost function but the 60% of them were trapped in undesired local minima that were substantially worse than their corresponding EKB plans.

Conclusion

Evolving knowledge‐base planning is a novel automated planning technique guided by the predicted three‐dimensional dose distribution, which can evolve from low‐quality plans. EKB allows new beams to be used in the automated planning workflow for superior plan quality.
A variational method for analysis of laminates with parallel arrays of intralaminar cracks
Authors: Vinogradov Vladimir
Published: June 2019

This paper presents a robust variational method for prediction of the effective thermoelastic properties of laminates with parallel, but not necessarily coplanar intralaminar cracks. Arbitrary laminate layup, crack patterns, and any in‐plane forces and bending moments, and temperature change can be treated simultaneously. The method is based on the principle of minimum complementary energy. The admissible in‐plane stress components are assumed to be linear through the ply thickness. Simple matrix expressions are derived for the effective compliance matrix, thermal expansions and curvatures, and specific heat of a cracked laminate. Predictions for the Young's modulus, Poisson's ratio, shear modulus, flexural rigidity, and thermal expansion as functions of crack density for various laminates of symmetric and nonsymmetric layups demonstrated excellent agreement with experimental results of seven independently published studies. Accuracy and robustness of the method are complemented by the fact that no experimentally fitted parameters are required. It is shown that the same formalism can be applied to analysis of closed intralaminar cracks, as well as nonuniform and nonsymmetrical distributions of cracks.
Predictive value of C‐reactive protein and the Pediatric Risk of Mortality III Score for occurrence of postoperative ventilator‐associated pneumonia in pediatric patients with congenital heart disease
Authors: Sun Yuelin , Zhao Tianxin , Li Dong , Huo Junming , Hu Lan , Xu Feng
Published: June 2019

Importance

Ventilator‐associated pneumonia (VAP) is one of the most common complications after cardiac surgery in children with congenital heart disease (CHD). Early prediction of the incidence of VAP is important for clinical prevention and treatment.

Objective

To determine the value of serum C‐reactive protein (CRP) levels and the Pediatric Risk of Mortality III (PRISM III) score in predicting the risk of postoperative VAP in pediatric patients with CHD.

Methods

We performed a retrospective review of clinical data of 481 pediatric patients with CHD who were admitted to our pediatric intensive care unit. These patients received mechanical ventilation for 48 hours or longer after corrective surgery. On the basis of their clinical manifestations and laboratory results, patients were separated into two groups of those with VAP and those without VAP. CRP levels were measured and PRISM III scores were collected within 12 hours of admission to the pediatric intensive care unit. The Pearson correlation coefficient was used to evaluate the association of CRP levels and the PRISM score with the occurrence of postoperative VAP. A linear regression model was constructed to obtain a joint function and receiver operating curves were used to assess the predictive value.

Results

CRP levels and the PRISM III score in the VAP group were significantly higher than those in the non‐VAP group (P < 0.05). Receiver operating curves suggested that using CRP + the PRISM III score to predict the incidence of VAP after congenial heart surgery was more accurate than using either of them alone (CRP + the PRISM III score: sensitivity: 53.2%, specificity: 85.7%). When CRP + the PRISM III score was greater than 45.460, patients were more likely to have VAP.

Interpretation

Although using CRP levels plus the PRISM III score to predict the incidence of VAP after congenial heart surgery is more accurate than using either of them alone, its predictive value is still limited.
Comparison of magnetic resonance imaging and computed tomography to measure preoperative parameters of children with pectus excavatum
Authors: Sun Jihang , Chen Chenghao , Peng Yun , Zhang Yue , Tian Hongwei , Yu Jie , Cao Jun , Zeng Qi
Published: June 2019

Importance

Pectus excavatum (PE) is the most common thoracic wall deformity in children, we need a method which could be used to evaluate pulmonary functions and effects on development.

Objective

To evaluate the use of 3D T1‐weighted (3DT1) and mDIXON magnetic resonance imaging (MRI) sequences for measuring the thoracic parameters and morphology of children with PE, comparing the measurements with those made on computed tomography (CT).

Methods

This is a retrospective study of children with thoracic deformities who were hospitalized at the Department of Thoracic Surgery of the Heart Center, Beijing Children's Hospital, between June 2014 and June 2015. Chest CT was performed first, with the MRI scanning then being performed 0–3 days later. The mDIXON sequences were obtained in inspiratory and expiratory phases and the 3DT1 sequences were obtained during free breathing. Thoracic volume was measured using the acquired images.

Results

The lung volumes measured on mDIXON MRI and CT were highly correlated, with the Haller index not being significantly different between the two methods. Bland‐Altman analyses showed that lung, cardiac, and retrosternal parameters were similar between the two methods. Pulmonary parameters were higher with the end‐inspiratory phase mDIXON images than with the end‐expiratory phase images, as expected, while cardiac parameters were unaffected by the respiratory phase.

Interpretation

Thoracic volumes measured on mDIXON MRI in combination with held respiration could reflect lung volume functions and help in observing the movement functions of the lungs and heart. The method could be used instead of CT, avoiding subjecting the patient to potentially harmful radiation.
Structural characterization of β‐ketoacyl ACP synthase I bound to platencin and fragment screening molecules at two substrate binding sites
Authors: Patterson Edward I. , Nanson Jeffrey D. , Abendroth Jan , Bryan Cassie , Sankaran Banumathi , Myler Peter J. , Forwood Jade K.
Published: June 2019

The bacterial fatty acid pathway is essential for membrane synthesis and a range of other metabolic and cellular functions. The β‐ketoacyl‐ACP synthases carry out the initial elongation reaction of this pathway, utilizing acetyl‐CoA as a primer to elongate malonyl‐ACP by two carbons, and subsequent elongation of the fatty acyl‐ACP substrate by two carbons. Here we describe the structures of the β‐ketoacyl‐ACP synthase I from Brucella melitensis in complex with platencin, 7‐hydroxycoumarin, and (5‐thiophen‐2‐ylisoxazol‐3‐yl)methanol. The enzyme is a dimer and based on structural and sequence conservation, harbors the same active site configuration as other β‐ketoacyl‐ACP synthases. The platencin binding site overlaps with the fatty acyl compound supplied by ACP, while 7‐hydroxyl‐coumarin and (5‐thiophen‐2‐ylisoxazol‐3‐yl)methanol bind at the secondary fatty acyl binding site. These high‐resolution structures, ranging between 1.25 and 1.70 å resolution, provide a basis for in silico inhibitor screening and optimization, and can aid in rational drug design by revealing the high‐resolution binding interfaces of molecules at the malonyl‐ACP and acyl‐ACP active sites.
Photodetection Properties of Nonpolar a‐Plane GaN Grown by Three Approaches Using Plasma‐Assisted Molecular Beam Epitaxy
Authors: Pant Rohit Kumar , Singh Deependra Kumar , Roul Basanta , Chowdhury Arun Malla , Chandan Greeshma , Nanda Karuna K. , Krupanidhi Saluru B.
Published: June 2019

Present work focuses on improving the quality of nonpolar a‐plane GaN thin films by introducing unconventional new efficient growth conditions without compromising their UV photodetection properties. These epitaxial thin films are grown on r‐plane sapphire using three different growth approaches by plasma‐assisted molecular beam epitaxy (PAMBE). In situ reflection high‐energy electron diffraction (RHEED) analysis is performed during and after the growth to monitor the growth mode, and it is found that the films assumed desired 2D mode during the growth. The crystalline quality and the phase purity of the films are assessed with the help of high‐resolution X‐ray diffraction and Raman spectroscopy. All the films are found to contain compressive stress, which indicate that all the films are strained and epitaxial. The temporal response is carried out in all the three batches, which is very stable. Sensitivity, responsivity, transit time, and gain values are estimated. Highest responsivity and the corresponding gain are found to be around 25 AW−1, 86.47 at 1 V bias, respectively. These are the highest reported values so far for a‐plane GaN at such low voltages.
Surface Reconstructions of SrTiO3(110) Calibrated with STM and LEED
Authors: Yue Chengguang , Ying Pan , Xu Bo , Tian Yongjun
Published: June 2019

On the SrTiO3(110) surface, a series of reconstructions related to the O‐layer are created via repeated cycles of argon ion sputtering and annealing. These reconstructions, including the (2 × 8), (6 × 8), (1 × 10), and (4 × 4) structures, are studied with scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). Typical structural units in the reconstructed surfaces are identified. Meanwhile, the combined investigations with STM and LEED eliminates the interference that arises from the coexisting multiple structures, and clarifies the otherwise vague understanding of the (1 × 10) and (4 × 4) structures. Such surface reconstructions provide a potential platform for developing molecular ordering and photocatalytic applications.
Rational Design of Sterically Hindered and Unsymmetrical NpyNimOph Pincer‐Type Ligands and Their Palladium(II) Complexes: Catalytic Applications in Suzuki–Miyaura Reaction and Allylation of Aldehydes
Authors: Maji Ankur , Singh Ovender , Rathi Sweety , Singh U. P. , Ghosh Kaushik
Published: June 2019

Palladium(II) complexes 1–4 [Pd(L1 to L4)Cl] derived from pincer‐type tridentate ligands having NpyNimOph donors were synthesized from ligands L1H to L4H (where L1H=(2‐phenyl‐2‐(pyridin‐2‐ylmethyl)hydrazono)methyl)phenol, L2H =[2‐((2‐phenyl‐2‐(pyridinyl‐2‐ylmethyl) hydrazono) methyl) phenol], L3H=[2‐((2‐benzyl‐2‐phenylhydrazono) methyl)‐4,6‐di‐tert‐butylphenol], and L4H=[2‐((2‐benzyl‐2‐phenylhydrazono)methyl)‐6‐(tert‐butyl)‐4‐methoxy phenol where H stands for dissociable proton)in quantitative yields. Synthesized ligands L1H to L4H and corresponding palladium(II) complexes 1–4 were characterized by NMR, IR and HR‐MS spectroscopic studies. Molecular structures of ligand L4H and complexes 1 and 3 were determined by X‐ray crystallography. Complexes 1–4 were utilized as catalysts to investigate Suzuki–Miyaura cross‐coupling reaction upon catalyst loading 0.01 mol%. These catalysts also catalysed allylation of aldehydes upto 95% yield upon catalyst loading 0.5 mol% with broad substrate scopes. Theoretical and experimental investigation was performed to speculate reaction pathway of Suzuki–Miyaura cross‐coupling reaction. A reaction model has also proposed for allylation of aldehydes the presence of allyltributylstannane.
Experimental study on seismic performance of T‐shaped partly precast reinforced concrete shear wall with grouting sleeves
Authors: Li Jianbao , Fan Qiaoqiao , Lu Zheng , Wang Yan
Published: June 2019

Prefabricated structure has prominent advantages such as easy control of construction quality, saving fabricating time and natural resources, and reducing environmental pollution and construction noise. The mostly used structural system in high‐rise buildings is reinforced concrete shear wall structure, which has high load capacity and lateral stiffness. Focusing on the connection of reinforcements, three T‐shaped partly prefabricated reinforced concrete shear walls and one cast‐in situ specimen in same dimensions as a control group are tested under low‐frequency cyclic loading to analyze their seismic performances in this paper. During the experiment, the axial compression ratio of specimens is fixed at 0.3, 0.4, and 0.5. Through the observation of phenomena and data analysis, hysteretic curve, skeleton curve, stiffness degradation, ductility, and load bearing capacity are compared and analyzed. The results show that partly prefabricated reinforced concrete shear wall has similar load bearing capacity with the cast in situ specimen, and it also has excellent ductility, stiffness, and energy‐dissipating capacity. The experimental results and analysis indicate that partly prefabricated reinforced concrete shear wall has outstanding seismic performances; under effective and reliable design, it can be used in building structures to play the same role as cast in situ components.
Simulating subhourly variability of wind power output
Authors: Fertig Emily
Published: June 2019

As installed wind power capacity grows, subhourly variability in wind power output becomes increasingly important for determining the system flexibility needs, operating reserve requirements, and cost associated with wind integration. This paper presents a new methodology for simulating subhourly wind power output based on hourly average time series, which are often produced for system planning analyses, for both existing wind plants and expanded, hypothetical portfolios of wind plants. The subhourly model has an AR(p)‐ARCH(q) structure with exogenous input in the heteroskedasticity term. Model coefficients may be fit directly to high‐pass filtered historical data if it exists; for sets of wind plants containing hypothetical plants for which there are no historical data, this paper presents a method to determine model coefficients based on wind plant capacities, capacity factors, and pairwise distances. Unlike predecessors, the model presented in this paper is independent of wind speed data, captures explicitly the high variability associated with intermediate levels of power output, and captures distance‐dependent correlation between the power output of wind plants across subhourly frequencies. The model is parameterized with 1‐minute 2014 plant‐level wind power data from Electric Reliability Council of Texas (ERCOT) and validated out‐of‐sample against analogous 2015 data. The expanded‐capacity model, fit to 2014 data, produces accurate subhourly time series for the 2015 wind fleet (a 49% capacity expansion) based only on the 2015 system's wind plant capacities, capacity factors, and pairwise distances. This supports its use in simulating subhourly fleet aggregate wind power variability for future high‐wind scenarios.
Removal of COD from synthetic wastewater in vertical flow constructed wetland
Authors: Xu Qiaoling , Cui Lihua
Published: June 2019

Three vertical flow constructed wetlands, that is, system A (planted with Pennisetum sinese Roxb), system B (planted with Pennisetum purpureum Schum.), and system C (without plants as the control) were constructed to estimate the contribution of substrates, plants, and microorganisms to organic matter removal. The organic compounds accumulated in the substrate in systems A, B, and C were 12.03%, 11.91%, and 9.4%, respectively. Synergistic utilization of organic compounds by microorganisms and plants in systems A, B, and C were 80.95%, 81.58%, and 80.11%, respectively. Substrate interception and adsorption of organic compounds in plant systems A and B were more extensive than in the nonplant control system C. The total accumulative and absorptive capacity of systems A, B, and C was as follows: B (2,713 g) > A (2,698 g) > C (2,076 g). The amounts of insoluble organic accumulated on the upper substrates of the three systems showed the order C > A > B. No constructed wetland clogging occurred for A and B systems during the experiment, while system C suffered clogging in early September. Therefore, substrate blockage may be related to the type of organic compound accumulated. Accumulation of insoluble organic matter is the direct cause of system blockage.

Practitioner points

Substrate interception and adsorption of organic compounds in plant systems were more extensive than those in the nonplant control system.

Distribution characteristics of the surface layer were significantly higher than those of the middle and bottom layers.

Substrate blockage is related to the type of organic compound accumulated.

Accumulation of insoluble organic compounds may be the direct cause of system blockage.

The upper substrate is the main site for organic compound removal.
Fischer-Tropsch products from biomass-derived syngas and renewable hydrogen
Authors: Gruber Hannes , Groß Peter , Rauch Reinhard , Reichhold Alexander , Zweiler Richard , Aichernig Christian , Müller Stefan , Ataimisch Nabeel , Hofbauer Hermann
Published: June 2019

Global climate change will make it necessary to transform transportation and mobility away from what we know now towards a sustainable, flexible, and dynamic sector. A severe reduction of fossil-based CO2 emissions in all energy-consuming sectors will be necessary to keep global warming below 2 °C above preindustrial levels. Thus, long-distance transportation will have to increase the share of renewable fuel consumed until alternative powertrains are ready to step in. Additionally, it is predicted that the share of renewables in the power generation sector grows worldwide. Thus, the need to store the excess electricity produced by fluctuating renewable sources is going to grow alike. The “Winddiesel” technology enables the integrative use of excess electricity combined with biomass-based fuel production. Surplus electricity can be converted to H2 via electrolysis in a first step. The fluctuating H2 source is combined with biomass-derived CO-rich syngas from gasification of lignocellulosic feedstock. Fischer-Tropsch synthesis converts the syngas to renewable hydrocarbons. This research article summarizes the experiments performed and presents new insights regarding the effects of load changes on the Fischer-Tropsch synthesis. Long-term campaigns were carried out, and performance-indicating parameters such as per-pass CO conversion, product distribution, and productivity were evaluated. The experiments showed that integrating renewable H2 into a biomass-to-liquid Fischer-Tropsch concept could increase the productivity while product distribution remains almost the same. Furthermore, the economic assessment performed indicates good preconditions towards commercialization of the proposed system.
Observation of surface wave patterns modified by sub-surface shear currents
Authors: Smeltzer Benjamin K. , Æsøy Eirik , Ellingsen Simen Å.
Published: June 2019

We report experimental observations of two canonical surface wave patterns – ship waves and ring waves – skewed by sub-surface shear, thus confirming effects predicted by recent theory. Observed ring waves on a still surface with sub-surface shear current are strikingly asymmetric, an effect of strongly anisotropic wave dispersion. Ship waves for motion across a sub-surface current on a still surface exhibit striking asymmetry about the ship’s line of motion, and large differences in transverse wavelength for upstream versus downstream motion are demonstrated, all of which is in good agreement with theoretical predictions. Neither of these phenomena can occur on a depth-uniform current. A quantitative comparison of measured versus predicted average phase shift for a ring wave is grossly mispredicted by no-shear theory, but in good agreement with predictions for the measured shear current. A clear difference in wave frequency within the ring wave packet is observed in the upstream versus downstream direction for all shear flows, while wave dispersive behaviour is identical to that for quiescent water for propagation normal to the shear current, as expected. Peak values of the measured two-dimensional Fourier spectrum for ship waves are shown to agree well with the predicted criterion of stationary ship waves, with the exception of some cases where results are imperfect due to the limited wavenumber resolution, transient effects and/or experimental noise. Experiments were performed on controlled shear currents created in two different ways, with a curved mesh and beneath a blocked stagnant-surface flow. Velocity profiles were measured with particle image velocimetry, and surface waves with a synthetic schlieren method. Our observations lend strong empirical support to recent predictions that wave forces on vessels and structures can be greatly affected by shear in estuarine and tidal waters.
Spark channel dynamics in railgun switches in unipolar and oscillatory discharges
Authors: Kharlov A.V.
Published: June 2019

Spark gaps are often used to commute energy in the discharge of a capacitive storage to a load. In some applications, a unipolar pulse is not feasible, and an oscillatory (underdamped sinusoidal) regime must be realized for the discharge of the capacitor bank. Spark gaps, which were developed for unipolar discharge, cannot be directly employed in an under-damped (oscillatory) regime since at the transition of the current through zero, the spark channel could stop motion and ignite in the following half period. This work has two main objectives: (i) To develop and test a simulation model of spark channel motion in linear rail geometry, which must be valid for both the oscillatory and unipolar regimes of capacitor bank discharge; and (ii) to investigate arc motion and electrode heating, depending on the current and charge transfer, over a wide range of operation. A self-consistent treatment of plasma motion and electrode heating (taking into account the radiation of a plasma channel) is applied in the present paper, and it is shown that radiation can significantly impact on the temperature of the electrodes. Electrode ablation and the temperature dependence of the main thermal parameters are also taken into account. Stainless steel (Cr/Ni/Ti 18/10/0.6÷0.8), copper (Cu), chromium (Cr), tungsten (W), and molybdenum (Mo) are used here as electrode materials since these materials are widely used for the manufacture of electrodes. The results of numerical calculations are compared with experimental results, and conditions are defined for reduced electrode erosion.
Speeding and Speed Modification of Older Drivers: Does Vehicle Type Make a Difference?
Authors: Cull Andrew W. , Porter Michelle M. , Nakagawa Satoru , Smith Glenys A. , Rapoport Mark J. , Marshall Shawn C. , Bédard Michel , Tuokko Holly , Vrkljan Brenda , Naglie Gary , Myers Anita M. , Mazer Barbara
Published: June 2019

The purpose of this study was to examine whether vehicle type based on size (car vs. other = truck/van/SUV) had an impact on the speeding, acceleration, and braking patterns of older male and female drivers (70 years and older) from a Canadian longitudinal study. The primary hypothesis was that older adults driving larger vehicles (e.g., trucks, SUVs, or vans) would be more likely to speed than those driving cars. Participants (n = 493) had a device installed in their vehicles that recorded their everyday driving. The findings suggest that the type of vehicle driven had little or no impact on per cent of time speeding or on the braking and accelerating patterns of older drivers. Given that the propensity for exceeding the speed limit was high among these older drivers, regardless of vehicle type, future research should examine what effect this behaviour has on older-driver road safety.
Microbes Spotted in “Polyextreme” Hot Springs
Authors: Kornei Katherine
Published: June 2019

Hot springs that are as acidic as battery acid are home to single-celled microorganisms that may indicate that life could have been sustained on ancient Mars.
Planetary Low Tide May Force Regular Sunspot Sync Ups
Authors: Cartier Kimberly
Published: June 2019

A regular alignment of the planets—no, it’s not pseudoscience—makes a strong enough tug to regulate the Sun’s 11- and 22-year cycles.
Podcast: Night of the Killer Smog
Authors: Lipuma Lauren
Published: June 2019

In the latest episode of its Centennial series, AGU’s Third Pod from the Sun tells the story of two air quality disasters that served as catalysts for clean air regulations in the mid-20th century.