bluuebunny/crossref_metadata_2025_split huggingface dataset:
Technical Note: Improving VMAT delivery efficiency by optimizing the dynamic collimator trajectory
Authors: Bokrantz Rasmus , van Amerongen Jacobus H.M. , Craft David 
Published: June 2019

PurposeTo provide a method for optimizing the multileaf collimator angle trajectory in volumetric modulated arc therapy (VMAT) in order to make VMAT delivery and planning more efficient.MethodsStatic fluence maps are optimized at a 10‐degree spacing around the patient. Sliding window delivery time of each of these fields is computed for a large set of possible collimator orientations. An optimal trajectory, which selects a collimator angle for each field and assures that the collimator angles do not differ excessively between adjacent fields, is computed by solving a network flow model of a shortest path problem.ResultsFor four clinical cases (two brains, an anal, and a spine), we demonstrate time reductions from 6% to 32% (average: 24%) for the optimal static angle vs the worst static angle. Further reductions from 3% to 17% (average 9%) are achievable when dynamic collimator trajectories are allowed.ConclusionsDynamic collimator trajectories, which can be computed with an efficient linear programming formulation, can improve the efficiency of VMAT delivery.
Optimal control policies in service systems with limited information on the downstream stage
Authors: Ansari Sina , Iravani Seyed M. R. , Shao Qifeng 
Published: June 2019

AbstractExisting models in multistage service systems assume full information on the state of downstream stages. In this paper, we investigate how much the lack of such information impacts jobs' waiting time in a two‐stage system with two types of jobs at the first stage. The goal is to find the optimal control policy for the server at the first stage to switch between type‐1 and type‐2 jobs, while minimizing the long‐run average number of jobs in the system. We identify control policies and corresponding conditions under which having no or partial information, the system can still capture the most benefit of having full information.
Stronger path‐based extended formulation for the Steiner tree problem
Authors: Filipecki Bartosz , Van Vyve Mathieu 
Published: June 2019

AbstractThe Steiner tree problem (STP) is a classical NP‐hard combinatorial optimization problem with applications in computational biology and network wiring. The objective of this problem is to find a minimum cost subgraph of a given undirected graph G with edge costs, that spans a subset of vertices called terminals. We present currently used linear programming formulations of the problem based on two different approaches—the bidirected cut relaxation (BCR) and the hypergraphic formulations (HYP), the former offering better computational performance, and the latter better bounds on the integrality gap. As our contribution, we propose a new hierarchy of path‐based extended formulations for STP. We show that this hierarchy provides better integrality gaps on graph instances used to define the worst‐case lower bounds on the integrality gap for both BCR and HYP. We prove that each consecutive level of our hierarchy is at least as strong as the previous one. Additionally, we also present numerical results showing that several difficult STP instances can be solved to integer optimality by using this hierarchy. Our approach can be adapted to variants of STP or applied to hypergraphic formulations for further potential improvement on the integrality gap bounds, in exchange for additional computational effort.
A sensitivity‐based approach to solving the inverse eigenvalue problem for linear structures carrying lumped attachments
Authors: Dawson Charles B. , Cha Philip D. 
Published: June 2019

SummaryThis paper presents an efficient algorithm for designing dynamical systems to exhibit a desired spectrum of eigenvalues. Focusing on combined systems of linear structures carrying various lumped element attachments, we apply the assumed‐modes method and the implicit function theorem to derive analytical expressions for eigenvalue sensitivities, which are used to efficiently determine the minimal set of structural modifications needed to achieve a set of desired eigenvalues. The proposed algorithm employs an adaptive step size, performs significantly better than existing approaches, and can be easily applied to a broad range of structures. Convergence properties and limitations on achievable eigenvalues are also discussed, and a number of case studies demonstrating the performance of the algorithm in a wide variety of different applications are also included.
Transverse failure of carbon fiber composites: Analytical sensitivity to the distribution of fiber/matrix interface properties
Authors: Shakiba Maryam , Brandyberry David R. , Zacek Scott , Geubelle Philippe H. 
Published: June 2019

SummaryAn analytic differentiation method is presented to calculate the sensitivity of the transverse failure response of carbon fiber composite laminates to the distribution parameters of the fiber/matrix interface properties. The method starts with the evaluation of the sensitivities of the transverse failure response with respect to the interface properties of each fiber, ie, the cohesive failure strength and the critical displacement jump. These individual sensitivities are then used to calculate the sensitivities with respect to the mean and standard deviation of the interface properties. The derived sensitivities are implemented in a nonlinear interface‐enriched generalized finite element method solver specially developed for this application. The interface‐enriched generalized finite element method solver combines a cohesive modeling of the fiber/matrix interface failure with finite element meshes that do not conform to the composite microstructure. The approach is first demonstrated on a model material involving a one‐dimensional domain containing N cohesive interfaces described by randomly selected cohesive failure properties. The method is then applied to the more complex problem of a composite laminate involving a large number of fibers.
Study and optimization of alternative MBE‐deposited metallic precursors for highly efficient kesterite CZTSe:Ge solar cells
Authors: Giraldo Sergio , Kim Shinho , Andrade‐Arvizu Jacob Antonio , Alcobé Xavier , Malerba Claudia , Valentini Matteo , Tampo Hitoshi , Shibata Hajime , Izquierdo‐Roca Victor , Pérez‐Rodríguez Alejandro , Saucedo Edgardo 
Published: June 2019

AbstractNowadays, most of the best efficiencies of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells are obtained from absorber layers fabricated using sequential processes, including the deposition of metallic stack precursors, typically by sputtering, and followed by reactive annealing under chalcogen atmosphere. The sputtering technique is widely known for the easy growth of metallic layers, although the deposition rates, growth morphology and nucleation, or the roughness can sometimes be an issue leading to inhomogeneities in the final layers. Nevertheless, MBE (molecular beam epitaxy) technique could have some advantages to obtain high‐quality metallic layers, with accurate control of the growth due to ultra‐high vacuum conditions and high purity. In this work, we study the use of advanced MBE systems to grow metallic stack precursors, alternatively to sputtering or thermal evaporation techniques, to obtain high‐quality CZTSe:Ge absorbers. Due to differences in the nature of each type of precursor, thermal annealing optimizations are presented by modifying some critical selenization parameters, such as the temperature or the selenium amount in order to obtain well‐crystallized absorbers. Detailed morphological, compositional, and structural characterizations show relevant features of each precursor, mainly related to the formation of MoSe2 at the back interface, and Se and Sn composition after selenization in different conditions. Regarding the solar cell devices, main efficiency limitations come from VOC and FF, which could be tentatively related to a noncontrolled selenization; different precursor reactivity, porosity, or composition; and different alkali diffusion during the reactive annealing. Finally, in the first optimization, a 9.2% efficiency device has been achieved with promising perspectives for future improvements.
Random copolymerization of l‐lactide and ε‐caprolactone by aluminum alkoxide complexes supported by N2O2 bis(phenolate)‐amine ligands
Authors: Chumsaeng Phongnarin , Haesuwannakij Setsiri , Virachotikul Arnut , Phomphrai Khamphee 
Published: June 2019

ABSTRACTThe bowl‐shaped aluminum alkoxide complexes bearing N2O2 bis(phenolate)‐amine ligands having different side arms as pyridine (1), dimethyl amine (2), and diethyl amine (3) were shown to be highly efficient and well behaved in the homopolymerization and copolymerization of l‐lactide (LA) and ε‐caprolactone (ε‐CL) at 100 °C. The rates of copolymerization are similar for Complexes 1–3 where nearly full conversions were achieved in 60 h for [LA]:[CL]:[Al] ratio of 50:50:1. The minor adjustment of the side arms of the Catalysts 1–3 gave profound differences in the LA/ε‐CL copolymer sequences where tapered, gradient, and highly random structures were obtained in one system, respectively. The chelation of LA to Al metal after ring‐opening process and suitable steric hindrance of the side arms were believed to participate and saturate the aluminum metal centers giving different copolymer structures. The random LA/ε‐CL copolymer structure was confirmed by nuclear magnetic resonance and differential scanning calorimetry analysis. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1635–1644
Zr(IV)‐Crosslinked Polyacrylamide/Polyanionic Cellulose Composite Hydrogels with High Strength and Unique Acid Resistance
Authors: Dai Xiaofu , Wang Jianquan , Teng Fei , Shao Ziqiang , Huang Xiaonan 
Published: June 2019

ABSTRACTRecently, metal coordination has been widely utilized to fabricate high‐performance hydrogels, but conventional metal‐based hydrogels face some drawbacks, such as staining or acid lability. In the present study, a novel kind of colorless Zr(IV)‐crosslinked polyacrylamide/polyanionic cellulose (PAM/PAC) composite hydrogel with unique acid resistance was constructed via acrylamide polymerization in a PAC solution, followed by posttreatment in a zirconium oxychloride (ZrOCl2) solution. The prepared gels were characterized in terms of Fourier transform infrared spectroscopy, scanning electron microscopy, and tensile and compressive mechanics, as well as acid resistance. Inside the gels, the synergistic action of hydrogen bonding and Zr(IV) coordination is responsible for their improved mechanical properties and good energy dissipation ability. One hydrogel with nearly 90 wt % of water content can sustain approximately 5 MPa of compression stress at 90% strain without damage. Both microscopic network structures and macroscopic mechanics demonstrate facile adjustability via changing the PAC dosages in polymerization and/or ZrOCl2 concentrations in posttreatment. Moreover, the gels present unexpected acid resistance due to the strong Zr(IV) coordination with PAC, demonstrating their potential application as hydrogel electrolytes in supercapacitors. The current work provides a new approach to fabricate metal coordination‐based high strength, colorless hydrogels with acid resistance. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 981–991
Database analysis of patients with hepatocellular carcinoma and treatment flow in early and advanced stages
Authors: Akada Keishi , Koyama Noriyuki , Taniguchi Shigeru , Miura Yuji , Aoshima Ken 
Published: June 2019

AbstractDespite recent developments in treatment modalities and diagnosis, the prognosis of advanced hepatocellular carcinoma (HCC) remains unsatisfactory. To gain insight into treatment decisions for HCC patients, their characteristics and treatment flow in the early and advanced stages were examined. HCC patients' characteristics and treatment flow were retrospectively analyzed using the Japanese medical claims database. The 8999 patients' mean age at HCC diagnosis was 71.1 years, with no difference between early (Stage I/II) and advanced (Stage III/IV) stages. The mean observation period was 26.2 months, shorter in advanced than in early stages. HCV hepatitis was reported in 52.0% of HCC patients, with concomitant hypertension in 53.4%, type 2 diabetes in 45.8%, cirrhosis in 39.3%, and hyperlipidemia in 15.5%. The rates of HCV hepatitis, hypertension, and hyperlipidemia decreased with stage progression. Analysis of treatment flow showed that, at all disease stages, transcatheter arterial chemoembolization (TACE) was the most common first to fourth‐line treatment. Epirubicin was the most frequently (44.1%) used chemotherapeutic agent for first‐line TACE, followed by miriplatin (23.6%) and cisplatin (12.3%). With stage progression, cisplatin use increased. Sorafenib was used concomitantly for first‐line TACE in 3.2% of patients, and its use increased significantly in advanced stages. Clear differences in baseline characteristics and treatment flow between early and advanced stages were identified. Continuous analysis of the database with longer follow‐up may provide useful information about treatment selection and prediction of outcome such as survival.
A reliability allocation method of mechanism considering system performance reliability
Authors: Zhang Yugang , Yu Tianxiang , Song Bifeng 
Published: June 2019

AbstractIt is generally believed that the reliability of a mechanical system is determined by its composition. The system operates properly when all of its components do not fail. Based on this assumption, the reliability of the system can be represented by the reliability of its components. A problem arises when applying this hypothesis to a system containing motion mechanisms. There is a phenomenon in motion mechanism that the components do not happen structural failure (we call it “Type I failure”) and joint failure (we call it “Type II failure”), but the function of the mechanism cannot meet the requirements (we call it “Type III failure”). A reliability allocation method, which synthetically considers the composition and Type III failure modes of the motion mechanism, is proposed to solve this problem. A relative dispersion factor is introduced to describe the failure dependence of components and is proposed to calculate the complexity and criticality. A series system reliability allocation model considering three types of failure modes is established. Finally, using an airplane gear door lock mechanism as an example, a comparative analysis of the system reliability allocation results with and without considering Type III failure modes is made. The allocation results show the component reliability value without considering Type III failure modes is less than that when considering them, which will increase the system hazards. The result considering Type III failure modes is more reasonable than that from the traditional method.
Electronic factors determining the methane bond breaking process on small aluminum clusters
Authors: Alexandrou Eleni I. , Groß Axel , Bacalis Naoum C. 
Published: June 2019

AbstractIn order to understand the catalytic activity of small metal clusters as a function of their size, we have studied the interaction of CH4 with Al4 and Al5 neutral and charged clusters, as well as neutral thermally expanded clusters in the two lowest lying spin states, using density functional theory. These calculations, via extended search, are used to determine the stable positions of H and CH3 near the cluster, and the transition state to break the H─CH3 bond. In order to understand the factors underlying the reactivity of the clusters, we have analyzed the electronic structure at the transition state. By an analysis of the change of the electronic density of states close to the transition state, we identify the orbitals involved in the bond breaking process. In conjunction with our previous studies of Al2 and Al3 clusters, we find that the small Al clusters, except for Al5, lower the CH3─H dissociation barrier with respect to the gas‐phase value, although Al lacks occupied d‐orbitals. Still, Al5 does not catalyze methane bond breaking, which is attributed to the required interaction with low‐lying Al sp‐states. Furthermore, in all cases where stable methyl‐aluminum‐hydrides are possible, the recombinative desorption of methane is studied by vibrational analysis and application of transition state theory.
Automated continuous monitoring and response to toxic subsurface vapors entering overlying buildings—Selected observations, implications and considerations
Authors: Kram Mark L. , Hartman Blayne , Clite Nova 
Published: June 2019

AbstractVapor intrusion characterization and response efforts must consider four key interactive factors: background indoor air constituents, preferential vapor migration pathways, complex patterns of vapor distribution within buildings, and temporal concentration variability caused by pressure differentials within and exterior to structures. An additional challenge is found at sites contaminated by trichloroethylene (TCE), which in the United States has very low indoor air screening levels due to acute risk over short exposure durations for sensitive populations. Timely and accurate characterization of vapor intrusion has been constrained by traditional passive time‐averaging sampling methods. This article presents three case studies of a robust new methodology for vapor intrusion characterization particularly suited for sites where there is a critical need for rapid response to exposure exceedances to minimize health risks and liabilities. The new methodology comprises low‐detection‐level field analytical instrumentation with grab sample and continuous monitoring capabilities for key volatile constituents integrated with pressure differential measurements and web‐based reporting. The system also provides automated triggered alerts to project teams and capability for integration with engineered systems for vapor intrusion control. The three case studies illustrate key findings and lessons learned during system deployment at two sites undergoing characterization studies and one site undergoing thermal remediation of volatile contaminants.
Ex‐situ efficacy analysis of brine remediation products in clay loam soil
Authors: Sanchez Dustin , Rogers William J. , Baker Kimberly 
Published: June 2019

AbstractThis study evaluated the effectiveness of gypsum and three proprietary products to remediate brine‐contaminated soil. The research objective was to determine if additives could increase plant cover germination in soils without costly prior soil‐washing or dilution techniques. The soil was shredded using a soil shredder equipped with a spray bar to apply the individual treatments of DeSalt Plus, SoilTech, Chlor*rid, and calcium sulfate (gypsum). Treatments were placed in 40‐mm high‐density polyethylene cells and small drainage systems were installed to allow removal of excess water. An initial 10‐point soil composite was taken from bulk untreated soils at a depth of more than 2.5 cm. Five‐point composite samples were collected from the same depth at weekly intervals and analyzed for: electrical conductivity, sodium adsorption ratio, cation exchange capacity, sodium, calcium, magnesium, potassium, chlorides, and pH. The Gapon selectivity coefficient was calculated and utilized to quantify the affinity for binding between ionic alkali salt constituent groups Na+, Ca
++, and Mg
++. Soil analysis indicated product‐related improvements in and bioavailability of salts. The nature of the products requires some prior treatment such as soil washing or dilution using clean soil to lower electroconductivity levels and allow the site to vegetate.
Mesenchymal Stem Cells Reconditioned in Their Own Serum Exhibit Augmented Therapeutic Properties in the Setting of Acute Respiratory Distress Syndrome
Authors: Xu Amy L. , Rodriguez Luis A. , Walker Kerfoot P. , Mohammadipoor Arezoo , Kamucheka Robin M. , Cancio Leopoldo C. , Batchinsky Andriy I. , Antebi Ben 
Published: June 2019

Abstract
Mesenchymal stem cells (MSCs) are a promising form of therapy for acute respiratory distress syndrome (ARDS). The objective of this study was twofold: (a) to characterize cytokine expression in serum from ARDS subjects receiving MSCs and (b) to determine MSC function following “preconditioning” with ARDS serum. In phase I, serum from three cohorts of animals (uninjured [no ARDS, n = 4], injured untreated [n = 5], and injured treated with approximately 6 million per kilogram MSCs [n = 7]) was analyzed for expression of inflammatory mediators. In phase II, the functional properties of bone marrow porcine MSCs were assessed following “preconditioning” with serum from the three cohorts. In phase III, the findings from the previous phases were validated using human bone marrow MSCs (hBM-MSCs) and lipopolysaccharide (LPS). Serum from injured treated animals had significantly lower levels of interferon-γ and significantly higher levels of interleukin (IL)-1 receptor antagonist (IL-1RA) and IL-6. Similarly, upon exposure to the injured treated serum ex vivo, the MSCs secreted higher levels of IL-1RA and IL-10, dampened the secretion of proinflammatory cytokines, exhibited upregulation of toll-like receptor 4 (TLR-4) and vascular endothelial growth factor (VEGF) genes, and triggered a strong immunomodulatory response via prostaglandin E2 (PGE2). hBM-MSCs demonstrated a similar augmented therapeutic function following reconditioning in a LPS milieu. Administration of MSCs modulated the inflammatory milieu following ARDS. Exposure to ARDS serum ex vivo paralleled the trends seen in vivo, which appear to be mediated, in part, through TLR-4 and VEGF and PGE2. Reconditioning MSCs in their own serum potentiates their immunotherapeutic function, a technique that can be used in clinical applications. Stem Cells Translational Medicine 2019;8:1092–1106
Clinical Relevance of Reductive Hepatectomy for Barcelona Clinic Liver Cancer Stages B and C Advanced Hepatocellular Carcinoma: A Single‐Center Experience of 102 Patients
Authors: Komatsu Shohei , Kido Masahiro , Tanaka Motofumi , Kuramitsu Kaori , Tsugawa ·Daisuke , Awazu Masahide , Gon Hidetoshi , Toyama Hirochika , Ueno Kimihiko , Fukumoto Takumi 
Published: June 2019

AbstractBackgroundThis study aimed to evaluate the clinical relevance of hepatectomy for Barcelona Clinic Liver Cancer (BCLC) stages B and C advanced hepatocellular carcinoma (HCC).MethodsA total of 314 patients (149 and 165 BCLC stages B and C, respectively) who underwent hepatectomy were included. Complete hepatectomy (without residual tumors after hepatectomy) and reductive hepatectomy (apparent residual tumors after hepatectomy) were performed for 212 and 102 patients, respectively. Short‐term operative and postoperative outcomes, as well as long‐term outcomes, were evaluated.ResultsThe median survival times of patients with stage B disease undergoing complete hepatectomy and reductive hepatectomy were 48.9 and 20.1 months, respectively (p = 0.0075), whereas those of patients with stage C disease were 19.5 and 17.6 months, respectively (p = 0.0140). The 3‐year overall survival rates of patients with stage B disease undergoing reductive hepatectomy with and without subsequent local treatments after surgery were 47.5% and 0%, respectively, whereas those of patients with stage C diseases were 18.6% and 0%, respectively.ConclusionsSurvival benefits are obvious for both BCLC stages B and C HCC when complete hepatectomy can be performed safely. Reductive hepatectomy is also acceptable for BCLC stages B and C when subsequent local treatment for remnant liver tumors can be performed safely after reductive hepatectomy. Without subsequent local treatment, reductive hepatectomy has little clinical relevance. Thus, a cautious approach to patient selection is required for this aggressive strategy.