bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tribological study of sintered iron based and copper based brake materials by pin-on-disc method
Authors: Özen Arda , Topuz Ahmet , Kurt Yusuf Umut , Zekeriyabeyoğlu Nagihan 
Published: February 2018

Abstract
In this study, iron based and copper based sintered brake materials have been investigated. Iron and copper based brake materials have been produced by powder metallurgy method. Hardness, experimental and theoretical density, porosity measurements and metallographic analysis have been performed to examine microstructure. Pin-on-disc tests have been carried out to understand friction behavior, to get the average coefficient of friction and to calculate wear rates of specimens. Pin-on-disc tests have been done at different radiuses (4, 6 and 9 mm), at different velocities (85, 100 and mm × s−1) and under a load of around 6.5 N. Test results show that the specimens have high porosity (25 to 26 %) because of the production methods. The phases and porosities can be also observed by metallographic analysis. Iron based brake materials have a lower coefficient of friction and lower wear rates in comparison with copper based brake materials. But copper based brake materials have a more stable abrasion profile during test period.
Dry sliding behavior of aluminum alloy 8011 with 4 % fly ash
Authors: Magibalan Subramaniam , Senthilkumar Palanisamy , Senthilkumar Chinnamuthu , Palanivelu Rajagoundar , Prabu Muthusamy 
Published: February 2018

Abstract
This research is focused on the fabrication of aluminum alloy 8011 with 4 % fly ash (FA) composite (AA8011-4 % FA) using the stir casting method. The dry sliding wear characteristics of the composite were investigated using various sliding parameters. A three-level central composite design experiment was developed using response surface methodology with various parameters such as load, time and sliding velocity varied in the range of 5 to 15 N, 5 to 15 min, and 1.5 to 4.5 m × s−1, respectively. Dry sliding wear tests were performed according to the experimental design using a pin-on-disc apparatus at room temperature. The obtained regression result indicated that the developed model performed well in relating the wear process parameters, and predicted the wear behavior of the composite. The surface plot showed that the wear rate increases with increase in load, time and sliding velocity. Moreover, the surface morphology of the worn-out composite was examined using a scanning electron microscope.
Optimization of the milling parameters for an Al/Si3N4 functionally graded composite using grey relational analysis
Authors: Venkatachalam Aravindh , Anurag Palakollu Venkata Sai , Sadanand Toppey Dhuruvan , Nachimuthu Radhika 
Published: February 2018

Abstract
This study involves the multi-objective optimization of end milling process parameters during machining of Al-Si5Cu3/Si3N4 functionally graded metal matrix composite that was fabricated using centrifugal casting route. The dimension of the cast sample was 150 × 150 × 20 mm3. The hardness of the sample was measured along the radial direction. It was found that the hardness at the outer periphery was greater than that of other points along the radial direction. Therefore, the machining experiment was carried out only at the outer periphery. Taguchi's design of experiments method was employed and sixteen levels of experiments were conducted by varying the input parameters namely the cutting speed (355, 500, 710 and 1000 rpm), the depth of cut (0.5, 0.9, 1.2 and 1.5 mm) and the feed rate (250, 315, 400 and 500 mm × min−1). Multi-objective optimization using grey relational analysis was performed and the optimal set of input parameters were found to be cutting speed of 1000 rpm, feed rate of 250 mm × min−1 and depth of cut of 1.5 mm. Using analysis of variance technique, it was found that cutting speed, depth of cut and feed rate have an influence of 63.57, 16.83 and 8 %, respectively, on the optimal solution.
A meta-analysis of outcomes and complications of magnetic resonance–guided focused ultrasound in the treatment of essential tremor
Authors: Mohammed Nasser , Patra Devi , Nanda Anil 
Published: February 2018

OBJECTIVEMagnetic resonance–guided focused ultrasound (MRgFUS) is a novel technique that uses high-intensity focused ultrasound to achieve target ablation. Like a lens focusing the sun’s rays, the ultrasound waves are focused to generate heat. This therapy combines the noninvasiveness of Gamma Knife thalamotomy and the real-time ablation of deep brain stimulation with acceptable complication rates. The aim of this study was to analyze the overall outcomes and complications of MRgFUS in the treatment of essential tremor (ET).METHODSA meta-analysis in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was made by searching PubMed, Cochrane library database, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL). Patients with the diagnosis of ET who were treated with MRgFUS were included in the study. The change in the Clinical Rating Scale for Tremor (CRST) score after treatment was analyzed. The improvement in disability was assessed with the Quality of Life in Essential Tremor Questionnaire (QUEST) score. The pooled data were analyzed by the DerSimonian-Laird random-effects model. Tests for bias and heterogeneity were performed.RESULTSNine studies with 160 patients who had ET were included in the meta-analysis. The ventral intermediate nucleus was the target in 8 of the studies. The cerebellothalamic tract was targeted in 1 study. There was 1 randomized controlled trial, 6 studies were retrospective, and 2 were prospective. The mean number of sonications given in various studies ranged from 11 ± 3.2 to 22.5 ± 7.5 (mean ± SD). The maximum delivered energy ranged from 10,320 ± 4537 to 14,497 ± 6695 Joules. The mean of peak temperature reached ranged from 53°C ± 2.3°C to 62.0°C ± 2.5°C. On meta-analysis with the random-effects model, the pooled percentage improvements in the CRST Total, CRST Part A, CRST Part C, and QUEST scores were 62.2%, 62.4%, 69.1%, and 46.5%, respectively. Dizziness was the most common in-procedure complication, occurring in 43.4%, followed by nausea and vomiting in 26.85% (pooled percentage). At 3 months, ataxia was the most common complication, occurring in 32.8%, followed by paresthesias in 25.1% of the patients. At 12 months posttreatment, the ataxia had significantly recovered and paresthesias became the most common persisting complication, at 15.3%.CONCLUSIONSThe MRgFUS therapy for ET significantly improves the CRST scores and improves the quality of life in patients with ET, with an acceptable complication rate. Therapy with MRgFUS is a promising frontier in functional neurosurgery.
A minimally invasive catheter-based ultrasound technology for therapeutic interventions in brain: initial preclinical studies
Authors: Ghoshal Goutam , Gee Lucy , Heffter Tamas , Williams Emery , Bromfield Corinne , Rund Laurie , Ehrhardt John M. , Diederich Chris J. , Fischer Gregory S. , Pilitsis Julie G. , Burdette E. Clif 
Published: February 2018

OBJECTIVEMinimally invasive procedures may allow surgeons to avoid conventional open surgical procedures for certain neurological disorders. This paper describes the iterative process for development of a catheter-based ultrasound thermal therapy applicator.METHODSUsing an ultrasound applicator with an array of longitudinally stacked and angularly sectored tubular transducers within a catheter, the authors conducted experimental studies in porcine liver, in vivo and ex vivo, in order to characterize the device performance and lesion patterns. In addition, they applied the technique in a rodent model of Parkinson’s disease to investigate the feasibility of its application in brain.RESULTSThermal lesions with multiple shapes and sizes were readily achieved in porcine liver. The feasibility of catheter-based focused ultrasound in the treatment of brain conditions was demonstrated in a rodent model of Parkinson’s disease.CONCLUSIONSThe authors show proof of principle of a catheter-based ultrasound system that can create lesions with concurrent thermode-based measurements.
Abdominal Aortic Calcifications Predict Survival in Peritoneal Dialysis Patients
Authors: Mäkelä Satu , Asola Markku , Hadimeri Henrik , Heaf James , Heiro Maija , Kauppila Leena , Ljungman Susanne , Ots-Rosenberg Mai , Povlsen Johan V. , Rogland Björn , Roessel Petra , Uhlinova Jana , Vainiotalo Maarit , Svensson Maria K. , Huhtala Heini , Saha Heikki 
Published: February 2018

Background Peripheral arterial disease and vascular calcifications contribute significantly to the outcome of dialysis patients. The aim of this study was to evaluate the prognostic role of severity of abdominal aortic calcifications and peripheral arterial disease on outcome of peritoneal dialysis (PD) patients using methods easily available in everyday clinical practice. Methods We enrolled 249 PD patients (mean age 61 years, 67% male) in this prospective, observational, multicenter study from 2009 to 2013. The abdominal aortic calcification score (AACS) was assessed using lateral lumbar X ray, and the ankle-brachial index (ABI) using a Doppler device. Results The median AACS was 11 (range 0 – 24). In 58% of the patients, all 4 segments of the abdominal aorta showed deposits, while 19% of patients had no visible deposits (AACS 0). Ankle-brachial index was normal in 49%, low (< 0.9) in 17%, and high (> 1.3) in 34% of patients. Altogether 91 patients (37%) died during the median follow-up of 46 months. Only 2 patients (5%) with AACS 0 died compared with 50% of the patients with AACS ≥ 7 ( p < 0.001). The adjusted hazard ratio for all-cause mortality was 4.85 (95% confidence interval [CI] 1.94 – 24.46) for aortic calcification (AACS ≥ 7), 2.14 for diabetes (yes/no), 0.93 for albumin (per 1 g/L), and 1.04 for age (per year). A low or high ABI were not independently associated with mortality. Conclusions Severe aortic calcification was a strong predictor of all-cause mortality in PD patients. The evaluation of aortic calcifications by lateral X ray is a simple method that allows the identification of high-risk patients.
Increased Serum Lactate in Peritoneal Dialysis Patients Presenting with Intercurrent Illness
Authors: Trinh Emilie , Saiprasertkit Nalinee , Bargman Joanne M. 
Published: February 2018

Background Lactate is the most commonly used buffer in peritoneal dialysis (PD) solutions. While previous studies have shown that serum lactate is normal in stable PD patients, the purpose of our study was to evaluate whether abnormal lactate values are more common in PD patients presenting to the emergency department (ED) and have the same significance as in the general population. Methods This observational cohort study assessed the prevalence of elevated serum lactate in PD patients presenting to the ED and evaluated clinical factors associated with an abnormal lactate value. Results We studied 172 patient visits in 89 PD patients to the ED at a major academic center between January 1, 2015, and December 31, 2015. An initial venous blood lactate value was performed in 91 visits (53%) and was found to be elevated (> 2 mmol/L) in 26 cases (29%). While an abnormal lactate was associated with signs of hemodynamic compromise such as intensive care unit (ICU) admission (26.9% vs 10.8%, p = 0.05) and tachycardia (46.2% vs 9.2%, p < 0.01), in half of the cases with elevated lactate, there was no evidence of hemodynamic instability at initial presentation. Moreover, an abnormal lactate value was also associated with a greater likelihood of under going an abdominal computed tomography (CT) scan (46.2% vs 18.5%, p < 0.01), but bowel ischemia was present in only 1 case. Conclusion An abnormal lactate value is often seen in PD patients presenting to the ED, even in the absence of signs of hemodynamic instability, and very rarely indicates bowel ischemia. We postulate that in the setting of an acute intercurrent illness, there is a transient disruption in the metabolism of lactate absorbed from the PD fluid. This novel observation suggests that elevated serum lactate in the sick PD patient does not necessarily indicate tissue hypoperfusion or gut ischemia and may obviate unnecessary investigations.
Comprehensive Approach to Peritoneal Dialysis-Related Peritonitis by Enteric Microorganisms. Comparison between Single Organism and Polymicrobial Infections
Authors: Ribera-Sánchez Roi , Pérez-Fontán Miguel , López-Iglesias Antía , García-Enríquez Alba , Rodríguez-Carmona Ana 
Published: February 2018

Background Peritoneal infections of enteric origin (EntP) have been classically investigated using partial strategies, focused on particular subgroups of microorganisms. A more comprehensive approach may facilitate the definition of the nomenclature and clinical presentation of these infections. Objectives To investigate the clinical presentation and outcomes of a full spectrum of EntP, with a particular interest in the comparison between single-organism and polymicrobial infections. Method Following an observational design, we investigated 165 single-organism and 83 polymicrobial peritonitis episodes with isolation of at least 1 enteric bacteria ( Enterobacteriaceae, Enterococcus spp. and/or intestinal anaerobics). We compared the risk of treatment failure for these 2 types of infection and explored the significance of the isolation of specific microorganisms and of their antibacterial susceptibility patterns. Results Polymicrobial EntP was associated with higher rates of hospitalization, more changes to initial antibiotic therapy, more surgical explorations, and higher mortality and treatment failure rates than monobacterial EntP. However, stratified and multivariate analyses revealed that the burden of these differences rested on the isolation of intestinal anaerobics (odds ratio [OR] 12.05, 95% confidence interval [CI] 2.53–31.09, p < 0.001) and/or Enterococcus faecium (OR 3.37, 95% CI 1.02–11.30, p = 0.046), while other polymicrobial infections were more comparable with single-organism peritonitis, except for even higher mortality rates in the former group. Lower antibiotic susceptibility of the isolations (OR 1.18, 95% CI 0.51–2.70, p = 0.70) did not perform as a predictor of treatment failure. Conclusion A comprehensive approach to peritoneal infections by intestinal microorganisms may provide a focused perspective of the clinical presentation and outcomes of these complications of peritoneal dialysis.
KELT-21b: A Hot Jupiter Transiting the Rapidly Rotating Metal-poor Late-A Primary of a Likely Hierarchical Triple System
Authors: Johnson Marshall C. , Rodriguez Joseph E. , Zhou George , Gonzales Erica J. , Cargile Phillip A. , Crepp Justin R. , Penev Kaloyan , Stassun Keivan G. , Gaudi B. Scott , Colón Knicole D. , Stevens Daniel J. , Strassmeier Klaus G. , Ilyin Ilya , Collins Karen A. , Kielkopf John F. , Oberst Thomas E. , Maritch Luke , Reed Phillip A. , Gregorio Joao , Bozza Valerio , Novati Sebastiano Calchi , D’Ago Giuseppe , Scarpetta Gaetano , Zambelli Roberto , Latham David W. , Bieryla Allyson , Cochran William D. , Endl Michael , Tayar Jamie , Serenelli Aldo , Aguirre Victor Silva , Clarke Seth P. , Martinez Maria , Spencer Michelle , Trump Jason , Joner Michael D. , Bugg Adam G. , Hintz Eric G. , Stephens Denise C. , Arredondo Anicia , Benzaid Anissa , Yazdi Sormeh , McLeod Kim K. , Jensen Eric L. N. , Hancock Daniel A. , Sorber Rebecca L. , Kasper David H. , Jang-Condell Hannah , Beatty Thomas G. , Carroll Thorsten , Eastman Jason , James David , Kuhn Rudolf B. , Labadie-Bartz Jonathan , Lund Michael B. , Mallonn Matthias , Pepper Joshua , Siverd Robert J. , Yao Xinyu , Cohen David H. , Curtis Ivan A. , DePoy D. L. , Fulton Benjamin J. , Penny Matthew T. , Relles Howard , Stockdale Christopher , Tan Thiam-Guan , Villanueva Steven 
Published: February 2018

Abstract
We present the discovery of KELT-21b, a hot Jupiter transiting the V = 10.5 A8V star HD 332124. The planet has an orbital period of P = 3.6127647 ± 0.0000033 days and a radius of

. We set an upper limit on the planetary mass of

at

confidence. We confirmed the planetary nature of the transiting companion using this mass limit and Doppler tomographic observations to verify that the companion transits HD 332124. These data also demonstrate that the planetary orbit is well-aligned with the stellar spin, with a sky-projected spin–orbit misalignment of

. The star has

K,

,

, and

km s−1, the highest projected rotation velocity of any star known to host a transiting hot Jupiter. The star also appears to be somewhat metal poor and α-enhanced, with

and [α/Fe] = 0.145 ± 0.053; these abundances are unusual, but not extraordinary, for a young star with thin-disk kinematics like KELT-21. High-resolution imaging observations revealed the presence of a pair of stellar companions to KELT-21, located at a separation of 1.″2 and with a combined contrast of

with respect to the primary. Although these companions are most likely physically associated with KELT-21, we cannot confirm this with our current data. If associated, the candidate companions KELT-21 B and C would each have masses of ∼0.12

, a projected mutual separation of ∼20 au, and a projected separation of ∼500 au from KELT-21. KELT-21b may be one of only a handful of known transiting planets in hierarchical triple stellar systems.
Turbulent Heating between 0.2 and 1 au: A Numerical Study
Authors: Montagud-Camps Victor , Grappin Roland , Verdini Andrea 
Published: February 2018

Abstract
The heating of the solar wind is key to understanding its dynamics and acceleration process. The observed radial decrease of the proton temperature in the solar wind is slow compared to the adiabatic prediction, and it is thought to be caused by turbulent dissipation. To generate the observed 1/R decrease, the dissipation rate has to reach a specific level that varies in turn with temperature, wind speed, and heliocentric distance. We want to prove that MHD turbulent simulations can lead to the 1/R profile. We consider here the slow solar wind, characterized by a quasi-2D spectral anisotropy. We use the expanding box model equations, which incorporate into 3D MHD equations the expansion due to the mean radial wind, allowing us to follow the plasma evolution between 0.2 and 1 au. We vary the initial parameters: Mach number, expansion parameter, plasma β, and properties of the energy spectrum as the spectral range and slope. Assuming turbulence starts at 0.2 au with a Mach number equal to unity, with a 3D spectrum mainly perpendicular to the mean field, we find radial temperature profiles close to 1/R on average. This is done at the price of limiting the initial spectral extent, corresponding to the small number of modes in the inertial range available, due to the modest Reynolds number reachable with high Mach numbers.
G331.512–0.103: An Interstellar Laboratory for Molecular Synthesis. I. The Ortho-to-para Ratios for CH3OH and CH3CN
Authors: Mendoza Edgar , Bronfman Leonardo , Duronea Nicolas U. , Lépine Jacques R. D. , Finger Ricardo , Merello Manuel , Hervías-Caimapo Carlos , Gama Diana R. G. , Reyes Nicolas , Åke-Nyman Lars 
Published: February 2018

Abstract
Spectral line surveys reveal rich molecular reservoirs in G331.512–0.103, a compact radio source in the center of an energetic molecular outflow. In this first work, we analyze the physical conditions of the source by means of CH3OH and CH3CN. The observations were performed with the APEX Telescope. Six different system configurations were defined to cover most of the band within (292–356) GHz; as a consequence, we detected a forest of lines toward the central core. A total of 70 lines of A/E–CH3OH and A/E–CH3CN were analyzed, including torsionally excited transitions of CH3OH (

). In a search for all the isotopologues, we identified transitions of 13CH3OH. The physical conditions were derived considering collisional and radiative processes. We found common temperatures for each A and E symmetry of CH3OH and CH3CN; the derived column densities indicate an A/E equilibrated ratio for both tracers. The results reveal that CH3CN and CH3OH trace a hot and cold component with

K and

K, respectively. In agreement with previous ALMA observations, the models show that the emission region is compact (

) with gas density n(H2) = (0.7–1)×107 cm−3. The CH3OH/CH3CN abundance ratio and the evidences for prebiotic and complex organic molecules suggest a rich and active chemistry toward G331.512–0.103.
Revisiting the Extended Schmidt Law: The Important Role of Existing Stars in Regulating Star Formation
Authors: Shi Yong , Yan Lin , Armus Lee , Gu Qiusheng , Helou George , Qiu Keping , Gwyn Stephen , Stierwalt Sabrina , Fang Min , Chen Yanmei , Zhou Luwenjia , Wu Jingwen , Zheng Xianzhong , Zhang Zhi-Yu , Gao Yu , Wang Junzhi 
Published: February 2018

Abstract
We revisit the proposed extended Schmidt law, which posits that the star formation efficiency in galaxies depends on the stellar mass surface density, by investigating spatially resolved star formation rates (SFRs), gas masses, and stellar masses of star formation regions in a vast range of galactic environments, from the outer disks of dwarf galaxies, to spiral disks and to merging galaxies, as well as individual molecular clouds in M33. We find that these regions are distributed in a tight power law as

∝

, which is also valid for the integrated measurements of disk and merging galaxies at high-z. Interestingly, we show that star formation regions in the outer disks of dwarf galaxies with

down to 10−5

yr−1 kpc−2, which are outliers of both the Kennicutt–Schmidt and Silk–Elmegreen laws, also follow the extended Schmidt law. Other outliers in the Kennicutt–Schmidt law, such as extremely metal-poor star formation regions, also show significantly reduced deviation from the extended Schmidt law. These results suggest an important role for existing stars in helping to regulate star formation through the effect of their gravity on the midplane pressure in a wide range of galactic environments.
Molecular Reconnaissance of the β Pictoris Gas Disk with the SMA: A Low HCN/(CO+CO2) Outgassing Ratio and Predictions for Future Surveys
Authors: Matrà L. , Wilner D. J. , Öberg K. I. , Andrews S. M. , Loomis R. A. , Wyatt M. C. , Dent W. R. F. 
Published: February 2018

Abstract
The exocometary origin of CO gas has been confirmed in several extrasolar Kuiper belts, with CO ice abundances consistent with solar system comets. We here present a molecular survey of the β Pictoris belt with the Submillimeter Array (SMA), reporting upper limits for CN, HCN, HCO+, N2H+, and H2CO, as well as for H2S, CH3OH, SiO, and DCN from archival ALMA data. Nondetections can be attributed to rapid molecular photodissociation due to the A-star’s strong UV flux. CN is the longest lasting and most easily detectable molecule after CO in this environment. We update our nonlocal thermodynamic equilibrium excitation model to include UV fluorescence, finding it plays a key role in CO and CN excitation, and we use it to turn the SMA CN/CO flux ratio constraint into an upper limit of

% on the HCN/(CO+CO2) ratio of outgassing rates. This value is consistent with, but at the low end of, the broad range observed in solar system comets. If sublimation dominates outgassing, then this low value may be caused by decreased outgassing for the less volatile molecule HCN compared to CO. If instead UV photodesorption or collisional vaporization of unbound grains dominates outgassing, then this low ratio of rates would imply a low ice abundance ratio, which would in turn indicate a variation in cometary cyanide abundances across planetary systems. To conclude, we make predictions for future molecular surveys and show that CN and HCN should be readily detectable with ALMA around β Pictoris for solar-system-like exocometary compositions.