bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Microstrucutre on Dwell Fatigue in Dual-Phase Titanium Alloys
Authors: Harr Michelle , Pilchak Adam , Daly Samantha
Published: October 2020

Dual phase titanium alloys, such as Ti-6242, experience a significant reduction in fatigue lifetime when the peak load is held at each cycle. This type of sustained peak loading, also known as dwell fatigue, mimics the long periods of high mean stress experienced by titanium fan and compressor components during takeoff and cruise. The reduction in fatigue lifetime is known as the dwell debit, and is attributed to the phenomenon of load shedding. Both local microstructure and temperature are known to impact load shedding and thereby the macroscopic response of Ti-6242 when subject to dwell fatigue, but the underlying mechanisms are still under active investigation. This study utilized electron backscatter diffraction (EBSD) and digital image correlation (DIC) to characterize the role of local microstructure and temperature on load shedding during dwell fatigue. EBSD was used to determine local orientation and texture information, and DIC provided information about the heterogeneity of the strain distribution and plastic strain accumulation. Ex-situ tests were performed to investigate the link between the deformation of local microstructures and macroscopic damage. The resultant strain fields and orientation maps were statistically analyzed to provide quantitative insights into the impact of local microstructure on load shedding during dwell fatigue.
Recognition and Quantification of Dual Phase Titanium Alloy Microstructures Using Convolutional Neural Networks
Authors: Noraas Ryan , Venkatesh Vasisht , Rettberg Luke , Somanath Nagendra
Published: October 2020

Recent advances in machine learning and image recognition tools/methods are being used to address fundamental challenges in materials engineering, such as the automated extraction of statistical information from dual phase titanium alloy microstructure images to support rapid engineering decision making. Initially, this work was performed by extracting dense layer outputs from a pretrained convolutional neural network (CNN), running the high dimensional image vectors through a principal component analysis, and fitting a logistic regression model for image classification. Kfold cross validation results reported a mean validation accuracy of 83% over 19 different material pedigrees. Furthermore, it was shown that fine-tuning the pre-trained network was able to improve image classification accuracy by nearly 10% over the baseline. These image classification models were then used to determine and justify statistically equivalent representative volume elements (SERVE). Lastly, a convolutional neural network was trained and validated to make quantitative predictions from a synthetic and real, two-phase image datasets. This paper explores the application of convolutional neural networks for microstructure analysis in the context of aerospace engineering and material quality.
Effects of cold tandem rolling on microstructures and mechanical properties of TC16 titanium alloy wire for fastener use
Authors: Xiaoping SUN , Fengqi HOU , Hui YANG , Kaixuan Wang , Xianghong LIU
Published: October 2020

High-precision dimension controlling and special requirement of microstructures and mechanical for TC16 Alloy wire was obtained by cold rolling. In this paper, the effects of cold tandem rolling on M and STA mechanical of TC16 Alloy wire were investigated through Comparative study TC16 Alloy wire by cold tandem rolling and hot-draw. The results show that the M state tensile and yield strength of TC16 Alloy wire obtained by cold tandem was lower, while the ductility was higher. And this benefits the subsequent Cold Heading formability. The result of solid solution for TC16 Alloy wire by cold tandem rolling was evidenced, the tensile strength has been increased and the ductility has been reduced more drastically. To break down elongated α of Vertical microstructure ability and drastic machining deformation have significant contributions to the annealed ductility and solution strengthening. It is very positive to TC16 titanium alloy use for fastener of heat treatment strength with the cold tandem rolling technology application.
Orientation mapping of cp-Ti by reflected polarized light microscopy
Authors: Morales-Rivas Lucia , Böhme Luisa , Kerscher Eberhard
Published: October 2020

Deformation and fracture mechanisms, and therefore mechanical behavior, in metals and metallic alloys with hexagonal close packed structures, such as α-Ti, strongly depend on the crystal c-axis orientation of the grains. Taking advantage of the intrinsic optical anisotropy that these structures present, a computer-aided method based on conventional reflected polarized light microscopy has been developed for c-axis orientation mapping. The application of the method on texture-free and textured commercially pure Ti is proposed for the examination of relevant crystallographic features.
Generation of Microstructural Gradients for Improved Mechanical Properties via Thermo-Hydrogen Treatment of the Metastable Beta Titanium Alloys Beta CTM and Ti 10V-2Fe-3Al
Authors: Schmidt Christopher David , Macin Vitali , Schmidt Peter , Christ Hans-Jürgen
Published: October 2020

Structural components must be lightweight and produced resource-saving while still fulfil the increasing durability and reliability requirements. One approach to fulfil these requests is a temporary hydrogen charging of Ti-alloys, which generates lattice distortion and hydrides. The volume difference between hydride precipitates and the alloy matrix results in localized plastic deformation. This triggers recrystallization and enables a finer microstructure as attainable by a conventional heat treatment. The study aims at an elaboration of a thermo-hydrogen treatment that establishes a change in grain size and/or an alteration in distribution and morphology of strengthening secondary α precipitates as a function of the distance to surface (microstructural gradient). The gradient is based on a gradient of the hydride volume fraction. Generally, THT design requires kinetic (temperature dependency of the hydrogen diffusion coefficient DH) in addition to thermodynamic (H/β-Ti-alloy interaction) data, which has been obtained for Ti 3Al-8V-6Cr-4Mo-4Zr and Ti 10V-2Fe-3Al. Subsequent to a solution treatment the variation of hydrogenation time and temperature is operated to establish comparably slight microstructural gradients on these materials. For further investigations it is concluded that materials with less alloying elements ((α+β)-Ti-alloys (e.g.,Ti 6Al-4V)) than these β-Ti-alloys can satisfy the requirements to generate steeper microstructural gradients even better.
Effect of microstructure and cooling rate on the fatigue performance of TIMETAL® 575
Authors: Bodie M. , Thomas M. , Ayub A.
Published: October 2020

A key design consideration for material selection in the aerospace industry is weight reduction; with excellent strength to weight ratio, high temperature resistance, and fatigue performance, titanium alloys are extensively used. New titanium alloys continue to enhance performance and broaden the range of applications. Titanium Metals Corporation (TIMET) recently developed TIMETAL® 575 (Ti575), a high strength titanium alloy with superior fatigue performance over Ti-6Al-4V, aimed at aerospace applications where these properties are imperative i.e. aerospace turbine discs and blades. [1] [2]

This work intends to advance the understanding of the effect of thermal processing of Ti575, by investigating the effect of primary alpha (αp) volume fraction and cooling rate on tensile and fatigue performance in post forged heat-treated microstructures. Microstructural assessment and mechanical performance were completed and are discussed.

Three cooling methods from three solution heat-treat temperatures were investigated in this work. The results from these experiments were compared using optical microscopy, electron backscatter diffraction (EBSD), room temperature tensile and high cycle fatigue (HCF) tests.
The Difference between Hot and Cold Deformation and its Effect on Microstructure and Mechanical Properties of Near Beta Titanium Alloy
Authors: Grebenchshikov A.S. , Leder M.O. , Volkov A.V.
Published: October 2020

An investigation of cold and hot deformation and the subsequent heat treatment including the annealing at the (α+β)- field temperature and ageing of VST55531 alloy showed that the material after the cold drawing without the heat treatment has the extremely low values of uniform elongation and during the tensile test the strain becomes localized at a neck upon 0.2 % strain. The ageing of coldworked material improves the strength and increases a limit of uniform deformation and generally has a beneficial effect on a strengthto-ductility ratio of alloy probably due to achieving a special morphology of secondary α-phase. The obtained values of the combination of strength and ductility in the cold-worked material at 50% strain reduction degree are 1 625 MPa for UTS, 8% - El, 36% - RA, that exceed significantly the values obtained for the hot-worked and as-annealed material, and are attractive for application in products that require the increased strength and ductile characteristics.
Further Research on Hardenability of Ti-1023 β Alloy Leading to a New DOE
Authors: Prazak Bohumil
Published: October 2020

As part of a treatise on the hardenability of Ti-1023, a summary about the nucleation mechanisms of primary and secondary alpha, the viability of two-step aging, and existence of precipitation-free zones is provided. Assumptions are given on the nucleation mechanism of primary alpha particles and the effect of higher beta stabiliser content on stress-induced martensitic transformation. It is reminded that further research into two-step aging would be beneficial. A proposed design of the experiment deals with the existence of martensite in stressed samples, so that the martensitic transformation is minimized by an increased content of beta stabilisers, volume fraction of primary alpha, and beta grain size. Finally, a microstructure with stress-induced omega particles as precursors of secondary alpha particles may result in a better trade-off of mechanical properties; it is suggested that this be explored.
Effect of strain rate on α-lath thickness of TC17 alloy after deformation and subsequent heat treatment
Authors: Lu Zimin , Luo Jiao , Li Miaoquan
Published: October 2020

Effect of strain rate on α-lath thickness of TC17 alloy with a basketweave microstructure was studied in the present work. For this purpose, this alloy was deformed in the β phase region and subsequently soluted and aged in α+β phase region. Moreover, optical micrograph (OM) and electron backscatter diffraction (EBSD) were applied to analyze the change of lath thickness at different strain rates. The result showed that α-lath thickness increased with increasing strain rate. This phenomenon was possibly attributed to the higher degree of variant selection (DVS) at higher strain rate (0.1 s-1). The higher DVS was beneficial for the formation of parallel α-lath colonies during cooling after deformation. And, these parallel α-lath colonies would more easily grow up and coarsen during subsequent heat treatment. Therefore, α-lath at higher strain rate is more thick.
Development of Porous Titanium Sheet with High Porosity and Good Mechanical Properties
Authors: Goto Yasuhiko , Inoue Yosuke , Fujii Hideki , Horikawa Matsuhide
Published: October 2020

To respond to the requirements for porous Ti sheet with the balanced properties of high porosity and good mechanical properties, and to optimize the manufacturing conditions of the simple powder-filling plus sintering process, effects of sintering temperatures on density and bending strength in porous Ti sheet were investigated. The optimum sintering condition was 900-950 °C for 1h to obtain porous Ti sheet with the balanced density ratio (around 40%) and high bending strength. The polyhedron shape of HDH powders contributed to those balanced properties, in which localized sintering raised bending strength with keeping high porosity (low density). Using the optimum manufacturing conditions, large sized porous Ti sheet of 400 × 800 × 0.5 mm was successfully manufactured.
Macro-mesoscale microstructural evolution modeling under hot forging of a Ti-17 alloy with a lamellar (α+β) starting microstructure
Authors: Matsumoto Hiroaki , Yamanaka Kenta , Chiba Akihiko , Yamabe-Mitarai Yoko , Itsumi Yoshio
Published: October 2020

Microstructural conversion mechanisms under hot forging process (at temperatures ranging from 750 °C to 1050 °C and strain rates ranging from 10–3 s–1 to 1 s–1) of a Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti-17) alloy with a lamellar starting microstructure were experimentally identified in this work. After that, constitutive formulae for predicting the microstructural evolution were established followed by calculation using finite-element (FEM) analysis. In the α phase, a lamellae kinking is the dominant mode in the higher strain rate region and dynamic globularization frequently occurs at higher temperatures. On the other hand, continuous dynamic recrystallization is the dominant mode below the transition temperature, Tβ (880~890 °C) in the β phase. And, at conditions of lower strain rates and higher temperatures, dynamic recovery tends to be more active. For microstructural prediction, a set of constitutive equations modeling the microstructural evolution and forging properties are established by optimizing the experimental data followed by implementation in the DEFORM-3D software package. Herein, microstructural evolution on dynamic globularization process, dynamic recrystallization behavior are predicted according to both approaches of physical model and artificial neural network model followed by FEM simulation. In these calculated results, there is a satisfactory agreement between the experimental and simulated results, indicating that the established series of constitutive models can be used to reliably predict the properties of a Ti-17 alloy after forging.
Kangaroo Care zur Schmerzreduktion bei Frühgeborenen
Authors: Thiele Noy-Joelle , Tannen Antje
Published: October 2020

Werden Frühgeborene Schmerzen ausgesetzt, etwa durch häufige Fersenstiche, können sich diese Schmerzerfahrungen negativ auf ihre Entwicklung auswirken. Als effektive Methode zur Schmerzminderung hat sich das Kangaroo Care erwiesen, das auch den Bindungsaufbau zwischen Kind und Eltern fördert.
Was eine ketogene Diät bei therapierefraktärer Epilepsie bewirken kann
Authors: Elisabeth Razenberger , Leoni-Scheiber Claudia
Published: October 2020

Diagnose Epilepsie! Eine drastische Veränderung des Lebens von Kindern und Jugendlichen sowie ihrer Familien, die damit konfrontiert werden. Trotz vielfältiger therapeutischer Möglichkeiten bleibt etwa ein Drittel der Kinder therapieresistent. Der Einsatz der ketogenen Diät kann erwogen werden. In diesem Beitrag wird aufgezeigt, welche positiven Veränderungen durch diese Ernährungsform erzielt werden können, aber insbesondere auch, was es für Kinder und ihre Familien bedeutet, eine derart strenge Diät durchzuhalten.
Cartilage Regeneration with a Cell-free Collagen Type 1 Matrix (Part 2 – Experimental Aspects)
Authors: Roessler Philip Peter , Mueller-Rath Ralf , Wirtz Dieter Christian , Schildberg Frank Alexander
Published: October 2020

Cartilage regeneration with cell-free matrices has developed from matrix-associated autologous cartilage cell transplantation (MACT) over ten years ago. Adjustments to the legal framework and higher hurdles for cell therapy have led to the procedures being established as an independent alternative to MACT. These procedures, which can be classified as matrix-induced autologous cartilage regeneration (MACR), all rely on the chemotactic stimulus of a cross-linked matrix, which mostly consists of collagens. Given the example of a commercially available type I collagen hydrogel, the physicochemical properties of such a matrix are explained and the available experimental data highlighted in more detail. The interaction between different cell types and the chemotactic properties of the collagen has been investigated extensively and, from a clinical point of view, today offers various reference points for a smart modification of the described method to further improve clinical
outcomes. Since the origin of the cells in the ultimately formed repair tissue is still unrevealed, further investigations to clarify the exact mechanism are crucially needed.
EDTNA/ERCA-Neuigkeiten
Authors: Nipshagen Sabine
Published: October 2020

Die Frage der Umweltverträglichkeit betrifft auch die Dialyseeinrichtungen. Hochaktuell ist also das Thema unseres Webinars im Dezember „Green Dialysis“. Kennen Sie RenalPro? Im vorliegenden Beitrag möchte ich Ihnen unser Forum für alle in der Nephrologie Beschäftigten vorstellen. Zudem finden Sie weiter unten eine Ankündigung zur EDTNA/ERCA-Konferenz Anfang September 2021.
1500 Euro Preisgeld
Authors: Schäfer Christian
Published: October 2020

Die Thieme Gruppe schreibt im Jahr 2021 wieder den Förderpreis Nephrologische Pflege aus und stiftet das Preisgeld von 1500 Euro.
Modular Approaches to Cyclopentanoids and their Heteroanalogs
Authors: Kotha Sambasivarao , Tangella Yellaiah
Published: October 2020

Cyclopentanoids and their derivatives are interesting targets in synthetic organic chemistry due to their extensive applications in various branches of chemical sciences like pharmaceuticals, natural and non-natural products. In view of these applications, several synthetic strategies have been developed in the past three to four decades. In this article, we describe our work towards the synthesis of cyclopentanoids and their heteroanalogs involving diverse synthetic strategies during the past two decades. Among these, photo-thermal olefin metathesis, ring-closing metathesis, ring-rearrangement metathesis, cyclopentane annulation, [2+2+2] cycloaddition and Diels–Alder reactions have been used to assemble cyclopentane rings of diverse architecture.

1 Introduction

2 Synthesis of Spiro[4.4]nonane (A1) Derivatives

3 Synthesis of Octahydropentalene (A2) Derivatives

4 Synthesis of Linear Triquinanes (A3)

5 Synthesis Spiro Triquinanes (A4)

6 Synthesis of Angular Triquinane (A5) Systems

7 Synthesis of Hexahydro-2′H-spiro[cyclopentane-1,1′-pentalene] (A6) Ring System

8 Synthesis of Dispiro[4.1.47.25]tridecane (A7) Ring System

9 Synthesis of Hexahydro-1H-3a,7a-propanoindene Ring System

10 Synthesis of Linear Tetraquinanes (A11 and A12)

11 Synthesis of Tetrahydro-1′H,3′H-dispiro[cyclopentane-1,2′-pentalene-5′,1′′-cyclopentane] (A13) Ring System

12 Synthesis of Decahydro-1H,8H-dicyclopenta[a,h]pentalene (A14) Ring System

13 Synthesis of Dodecahydro-1H-dicyclopenta[a,d]pentalene (A15) Ring System

14 Synthesis of Octahydro-1′H-spiro[cyclopentane-1,2′-cyclopenta[c]pentalene] (A16) Ring System

15 Synthesis of Decahydrospiro[cyclopentane-1,7′-cyclopenta-[a]pentalene] (A17) Ring System

16 Synthesis of Compact Tetraquinane (A18)

17 Synthesis of Higher Polyquinanes

18 Conclusions

19 Acronyms
Synthesis of Hydrazinylpyridines via Nucleophilic Aromatic Substitution and Further Transformation to Bicyclo[2.2.2]octenes Fused with Two N-Aminosuccinimide Moieties
Authors: Kranjc Krištof , Ekar Jernej
Published: October 2020

Efficient and reliable synthesis of substituted hydrazinylpyridines in thick-wall ACE tubes via nucleophilic substitution of a chlorine substituent in different chloropyridines is presented. Hydrazine hydrate and alkylhydrazines were used as nucleophiles and simple alcohols and diethyl ether were the only organic solvents necessary, making the process environmentally and user friendly, potentially reaching 100% atomic efficiency. In the next step, transformations of succinic anhydride moieties fused to the bicyclo[2.2.2]octene framework into succinimide moieties via nucleophilic substitution of oxygens were conducted. As nucleophiles two of the synthesized hydrazinylpyridines (2-hydrazinyl-3-nitropyridine and 2-hydrazinyl-5-nitropyridine) and also hydrazine hydrate, phenylhydrazine, and 4-nitrophenylhydrazine were used. Reactions were again carried out in ACE tubes and only simple alcohols, diethyl ether, and acetone were needed as solvents. One of the prepared bicyclo[2.2.2]octene adducts displayed water solubility thus being a promising candidate for future studies as a novel bidentate ligand for various metal cations in aqueous solutions or acting as an unprecedented halogen bond acceptor.
Straightforward Synthesis of 3-Selenocyanato-Substituted Chromones through Electrophilic Selenocyanation of Enaminones under Grinding Conditions
Authors: Xiao Jun-An , Ren Ji-Wei , Huang Yan-Min , Cheng Xiu-Liang , Meng Ru-Fang , Qin Xiao-Shi , Peng Hai , Xie Zhen-Zhen , Cui Jian-Guo
Published: October 2020

A metal- and oxidant-free method for preparing 3-selenocyanato-substituted chromones from 2-hydroxyphenyl enaminones by using a newly developed electrophilic selenocyanating reagent is reported­. A series of 3-selenocyanato- or 3-thiocyanato-substituted chromones, as well as 3-selenocyanato- or 3-thiocyanato-substituted quinolinones was obtained in good to excellent yields under grinding reaction conditions. The generality and utility of this approach were demonstrated by a scale-up reaction and transformations of one of the products.
Potassium tert-Butoxide Promoted Synthesis of 4,5-Diaryl-2H-1,2,3-triazoles from Tosylhydrazones and Nitriles
Authors: Wu Luyong , Qiu Shanguang , Chen Yuxue , Song Xinming , Liu Li , Liu Xi
Published: October 2020

Intermolecular cycloaddition of tosylhydrazones with nitriles was investigated. t-BuOK was shown to be an excellent base for increasing the effectiveness of the reaction in this protocol, and homocoupling of the tosylhydrazones was significantly inhibited by using xylene as a solvent. Through this transformation, a variety of 4,5-diaryl-2H-1,2,3-triazoles were prepared in good to excellent yields and with high purities. The process is azide-free and transition-metal-free.
Designing the Secondary Coordination Sphere in Small-Molecule Catalysis
Authors: Zak Inbal L. , Gadekar Santosh C. , Milo Anat
Published: October 2020

The application of secondary-sphere interactions in catalysis was inspired by the hierarchical arrangement of the microenvironment of metalloprotein active sites and has been adopted mainly in organometallic catalysis. The study of such interactions has enabled the deliberate orientation of reaction components, leading to control over reactivity and selectivity by design. Although not as common, such interaction can play a decisive role in organocatalysis. Herein, we present several examples of small-molecule organometallic- and organocatalysis, highlighting the advantages offered by carefully designing the secondary sphere.

1 Introduction

2 Secondary-Sphere Design in Organometallic Catalysis

3 Secondary-Sphere Modification in Organocatalysis

4 Using Statistical Analysis to Systematically Tune and Probe Secondary-Sphere Interactions

5 Conclusion
Successful Treatment of Driveline Infection with Vacuum-Assisted Closure Therapy and Instillation Therapy
Authors: Kilo Juliane , Dumfarth Julia , Höfer Daniel , Grimm Michael
Published: October 2020

Background Driveline infection is a serious complication in left ventricular assist device (LVAD) patients. We report the case of a patient who was successfully treated by combining instillation and vacuum-assisted closure (VAC) therapy.

Case Description A 65-year-old LVAD patient presented with recurrent driveline infection. Local therapy with VAC therapy in combination with instillation of polyhexanide was performed for 2 weeks. The patient remains free from infection for twelve months by now.

Conclusion This case is the first to present the combination of polyhexanide instillation with VAC as treatment for driveline infection. This therapy may thus be an option for patients who lack any other surgical option.
A Morphometric Study of Stylomastoid Foramen with Its Clinical Applications
Authors: Tewari Siddharth , Gupta Chandni , Palimar Vikram
Published: October 2020

Objective To prevent damage to the facial nerve while doing surgery and to give facial nerve block by anesthetics near the stylomastoid foramen we should know its distance from the important anatomical landmarks. So, this study aims to study the location of stylomastoid with respect to nearby anatomical landmarks.

Materials and Methods The study was performed on 58 dry skulls. Measurements of stylomastoid foramen were taken from various anatomical landmarks on both sides of the skull. Data analysis was done by using the Statistical Package for Social Sciences (SPSS) 19 version.

Results The mean distance of the center of the stylomastoid foramen (CSMF) to the tip of the mastoid process was 1.60, 1.57 cm on the right and left side, respectively. The mean distance of CSMF to the upper end of the anterior border of the mastoid process was 1.42, 1.39 cm on the right and left side, respectively. The mean angle between CSMF and tip of the mastoid process was 51.6 degrees, 53.5 degrees on right and left side, respectively. The mean distance of CSMF to the center of jugular foramen was 1.27, 1.26 cm on the right and left side, respectively. The position of the stylomastoid foramen in relation to a transverse line passing through the upper end of the anterior border of both mastoid processes was anterior in 82.7%, 94.8% of cases on the right and left side, respectively.

Conclusion These measurements will aid neurosurgeons in doing surgeries near the stylomastoid foramen or anesthetics to give facial nerve block near the foramen.
Effects of Preoperative Embolization on Juvenile Nasopharyngeal Angiofibroma Surgical Outcomes: A Study of the Kids' Inpatient Database
Authors: Choi Jonathan S. , Yu Justin , Lovin Benjamin D. , Chapel Alyssa C. , Patel Akash J. , Gallagher K. Kelly
Published: October 2020

Objectives The aim of the study is to evaluate the effect of preoperative vascular embolization (PVE) on juvenile nasopharyngeal angiofibroma (JNA) surgical outcomes using a national pediatric hospitalization database.

Methods The health care cost and utilization project Kids' Inpatient Database was queried for all cases of operative management of JNA between the years of 1997 and 2016. Cases were stratified based on whether the patient received PVE. A multiple linear regression was used to predict the effect of PVE on hospital length of stay (LOS) and total cost while controlling for patient demographic factors and comorbidities. The odds ratio (OR) of receiving a perioperative blood transfusion was computed using a binary logistic regression for PVE patients.

Results A total of 473 patients who underwent JNA surgical resection in this time period were identified. The use of PVE has increased from 0% in 1997 to 66% of all cases by 2016. PVE was found to decrease LOS by 1 day (p = 0.036) and decrease the odds of needing a perioperative blood transfusion (OR = 0.511, p = 0.041). Patients receiving PVE were charged an additional $35,600 (p < 0.001), but recent data in 2016 indicate that hospital costs for PVE are decreasing.

Conclusion PVE of JNA is becoming increasingly prevalent. Embolization results in decreased hospital LOS and lower odds of needing blood transfusions. While embolization increases the cost of management, this trend should be re-evaluated as this procedure is becoming more widespread.
Advancement of PI3 Kinase Inhibitor Combination Therapies for PI3K-Aberrant Chordoma
Authors: Heft Neal Molly E. , Michmerhuizen Nicole L. , Prince Mark E.P. , Kovatch Kevin J. , Owen John Henry J. , Zhai Jingyi , Jiang Hui , McKean Erin L. , Brenner J. Chad
Published: October 2020

Objectives Targeted inhibitors of the PI3 kinase (PI3K) pathway have shown promising but incomplete antitumor activity in preclinical chordoma models. The aim of this study is to advance methodology for a high-throughput drug screen using chordoma models to identify new combination therapies for chordoma.

Study Design Present work is an in vitro study.

Setting The study conducted at an academic research laboratory.

Materials and Methods An in vitro study on automated high-throughput screening of chordoma cells was performed using a library of 1,406 drugs as both mono- and combination therapies with PI3K inhibitors. Combination indices were determined for dual therapies and synergistic outliers were identified as potential therapeutic agents. T (brachyury) siRNA knockdown in combination with PI3K pathway inhibition was also assessed.

Results Fifty-nine combination therapies were identified as having potential therapeutic efficacy. Effective combinations included PI3K inhibitors with GSK1838705A (ALK/IGF-1R inhibitor), LY2874455 (VEGFR/FGFR inhibitor), El1 (selective Ezh2 inhibitor), and (-)-p-bromotetramisole oxalate (alkaline phosphatase inhibitor). The top ranking targets identified included ALK, PDGFR, VEGFR, aurora kinase, and BCL-2. T (brachyury) inhibition produced significant reduction in cell viability and growth; however PI3K inhibition in combination with T (brachyury) knockdown did not result in further reduction in growth and viability in vitro.

Conclusion High throughput with in vitro combination screening is feasible with chordoma cells and allows for rapid identification of synergistic dual-therapies. Potential combination therapies and targetable pathways were identified. T (brachyury) knockdown produced significant reduction in cell viability, but did not show additional benefit with PI3K pathway inhibition in this model. Further in vitro and in vivo validation of these therapeutic combinations is warranted.
The Interaction of Private and Public Governance: The Case of Sustainability Standards for Palm Oil
Authors: Brandi Clara
Published: October 2020

By providing insights into the interaction between private-driven and public-driven governance initiatives in the context of the “Roundtable of Sustainable Palm Oil” (RSPO) and the “Indonesian Sustainable Palm Oil” (ISPO), this article sheds new light the interaction between private and public governance. It investigates how the relationship between the RSPO and the ISPO evolves over time and who and what drives this evolution. While the interaction between these standard schemes has initially largely been characterized by competition, it has become more collaborative and also coordinated in nature. This article argues that the experimentalist architecture of palm oil governance has fostered mechanisms for coordination across public and private certification schemes and has helped to join up the separate components of the regime complex through productive interactions. At the same time, several gaps and challenges remain, especially in light of the different interests of the multiple public and private actors involved in palm oil.
Bursting during intermittency route to thermoacoustic instability: Effects of slow–fast dynamics
Authors: Tandon Shruti , Pawar Samadhan A. , Banerjee Subham , Varghese Alan J. , Durairaj Premraj , Sujith R. I.
Published: October 2020

Intermittency observed prior to thermoacoustic instability is characterized by the occurrence of bursts of high-amplitude periodic oscillations (active state) amidst epochs of low-amplitude aperiodic fluctuations (rest state). Several model-based studies conjectured that bursting arises due to the underlying turbulence in the system. However, such intermittent bursts occur even in laminar and low-turbulence combustors, which cannot be explained by models based on turbulence. We assert that bursting in such combustors may arise due to the existence of subsystems with varying timescales of oscillations, thus forming slow–fast systems. Experiments were performed on a horizontal Rijke tube and the effect of slow–fast oscillations was studied by externally introducing low-frequency sinusoidal modulations in the control parameter. The induced bursts display an abrupt transition between the rest and the active states. The growth and decay patterns of such bursts show asymmetry due to delayed bifurcation caused by slow oscillations of the control parameter about the Hopf bifurcation point. Further, we develop a phenomenological model for the interaction between different subsystems of a thermoacoustic system by either coupling the slow and fast subsystems or by introducing noise in the absence of slow oscillations of the control parameter. We show that interaction between subsystems with different timescales leads to regular amplitude modulated bursting, while the presence of noise induces irregular amplitude modulations in the bursts. Thus, we speculate that bursting in laminar and low-turbulence systems occurs predominantly due to the interdependence between slow and fast oscillations, while bursting in high-turbulence systems is predominantly influenced by the underlying turbulence.
Exact solutions of D-dimensional Klein–Gordon oscillator with Snyder–de Sitter algebra
Authors: Hemame Zoubir , Falek Mokhtar , Moumni Mustafa
Published: October 2020

We study the effects of Snyder–de Sitter commutation relations on relativistic bosons by solving analytically in the momentum space representation the Klein–Gordon oscillator in arbitrary dimensions. The exact bound state spectrum and the corresponding momentum space wave functions are obtained using Gegenbauer polynomials in the one-dimensional space and Jacobi polynomials in the D-dimensional case. Finally, we study the thermodynamic properties of the system in the high-temperature regime where we found that the corrections increase the free energy but decrease the energy, the entropy, and the specific heat that is no longer constant. This work extends the part concerning the Klein–Gordon oscillator for the Snyder–de Sitter case studied in two-dimensional space by Falek et al. [J. Math. Phys. 60, 013505 (2019)].
Programmable omni-resonance using space–time fields
Authors: Shiri Abbas , Schepler Kenneth L. , Abouraddy Ayman F.
Published: October 2020

Omni-resonant wave packets are pulsed optical beams that couple to planar cavities even when the wave packet bandwidth far exceeds the cavity resonant linewidth by virtue of a precise spatiotemporal structure introduced into the optical field. We demonstrate experimentally the synthesis of programmable omni-resonant wave packets in which a prescribed pulse spectrum is made to resonate with a planar cavity. Examples include controllable-bandwidth resonant spectral lines, spectral holes with tunable notch bandwidth, and even arbitrary resonant spectra. These novel resonant interactions are realized with no changes made to the cavity itself, and therefore, without compromising its quality factor—only sculpting the spatiotemporal spectrum of the incident field is required. Programmable omni-resonance allows harnessing resonant field enhancements over arbitrary spectral profiles without restriction to traditionally narrow resonant linewidths.
The role of hydrogen molecular effects on detachment in Magnum-PSI
Authors: Akkermans G. R. A. , Classen I. G. J. , Perillo R. , van der Meiden H. J. , Federici F. , Brezinsek S.
Published: October 2020

The hydrogen plasma-chemical processes responsible for tokamak divertor detachment are studied experimentally in the linear device Magnum-PSI, with a focus on molecular activated recombination (MAR) in hydrogen plasmas. Hydrogen plasmas with electron densities up to 6×1020 m−3 were created in Magnum-PSI, and hydrogen gas puffing was used to locally enhance plasma–neutral interaction. Thomson scattering and Balmer line spectroscopy measurements show that as neutral pressure is increased, the plasma passes through regimes dominated by ionization, MAR, and electron–ion recombination in turn. Heat and particle fluxes decrease monotonically with pressure. Fulcher band measurements show that in our plasma conditions, a simple model based on Franck–Condon excitation of a thermal vibrational distribution fails to describe the vibrational distribution of the upper state. These results serve as a benchmark for modeling suites that aim to simulate the ITER divertor and motivates their accurate treatment of the discussed processes, particularly MAR.
Tuning laser wavelength and pulse duration to improve the conversion efficiency and performance of EUV sources for nanolithography
Authors: Sizyuk Tatyana , Hassanein Ahmed
Published: October 2020

The optimum conditions for efficient extreme ultraviolet (EUV) sources in laser-produced plasma (LPP) depend on the ideal combination of several parameters such as laser wavelength, intensity, spot size, and pulse duration. These parameters need to be optimized in relation to the actual target size and geometry. The laser wavelength can play a major role in this regard. While target related effects are not significant in the case of a Nd:YAG laser, the achievable conversion efficiency (CE) of EUV sources produced by a CO2 laser from small Sn droplets can be several times lower compared to that from a flat Sn target. Improving the efficiency and performance of EUV sources requires detailed investigation of various laser/target combinations using comprehensive integrated models. We simulated and characterized in detail plasmas produced from the Sn droplet irradiated by lasers with various wavelengths. The optimum laser intensity with respect to the laser and target sizes was determined for a range of laser wavelengths from 1 μm to 10 μm. This work was inspired by the recent developments of lasers with a 2 μm wavelength. The laser pulse duration is another important parameter in the optimization of LPP for EUV sources. Our comprehensive HEIGHTS modeling showed that increasing the pulse duration of the 2 μm laser leads to an increase in the CE of EUV sources. Our results also indicate that a significant reduction in the kinetic energies of ions generated from LPP can be achieved by optimizing the laser pulse duration.
On the axisymmetric stability of tokamaks with ferromagnetic walls
Authors: Bardsley O. P. , Hender T. C.
Published: October 2020

Reduced activation ferritic steels are an attractive option for use in large structural components surrounding tokamak plasmas in future fusion power plants, but their ferromagnetic response to the confining magnetic fields must be properly understood. Simultaneously, the advantages of operating at high plasma elongation push tokamak designs toward scenarios that are more vulnerable to vertical displacement events. Passive conducting structures in present tokamaks slow these instabilities such that they may be feedback controlled, but the efficacy of this process is likely to be eroded by ferromagnetic effects. We approach two related analytical models—in cylindrical and spherical geometries—which qualitatively and quantitatively assess the impact of a ferritic steel wall on the vertical instability growth rate for a plasma of certain elongation. Distinct limits for magnetically thick and thin walls give key physical insight, but the dependence on magnetic permeability and wall geometry is, in general, quite complex. Equilibrium considerations, particularly with respect to radial force balance, are also encountered.
Substrate oxygen sponge effect: A parameter for epitaxial manganite thin film growth
Authors: Kang Kyeong Tae , Zhang Bruce , Sharma Yogesh , Paudel Binod , Wang Haiyan , Dowden Paul , Chen Aiping
Published: October 2020

The emergent phenomena in complex oxide thin films are strongly tied to the oxygen content, which is often engineered by the oxygen partial pressure during growth. However, such oxygen control by the growth pressure is challenging to synthesize for some oxide films, which requires a subtle control of the oxygen content. A parameter of controlling the oxygen content independent of the growth pressure is desired. Here, we propose a method of controlling the oxygen content of films by engineering the substrate before the growth. The oxide substrate serves as an oxygen sponge, which provides a tunable oxygen environment ranging from oxygen-rich to oxygen-poor for the film growth, depending on the pre-substrate annealing (PSA) conditions. Using manganite as a model system, we demonstrate that this simple PSA method leads to remarkable changes in the structure and physical properties of the as-grown films. This substrate oxygen sponge effect, driven by the large oxygen concentration gradient at high temperatures, can be applied to explore not only emergent interfacial phenomena but also the growth of a variety of functional oxide thin films and nanocomposites.
Investigation of process–structure–property relationship in ternary organic photovoltaics
Authors: Kaka Fiyanshu , Khanna Sumeet , Ramamurthy P. C. , Choudhury Abhik
Published: October 2020

Organic photovoltaics (OPVs) have held on to the race for providing a sustainable source of energy for more than two decades, and ternary OPVs have emerged as a promising candidate for harnessing solar energy. While the ternary OPVs have potential, optimization of the process parameters, particularly for deriving active-layer morphologies with high efficiencies, is non-trivial as the parameter space is large and a theoretical framework is necessary. This is specifically important for determining the appropriate compositions of the ternary blend which, upon phase-separation, lead to the formation of the heterogenous active layer with a distribution of three phases. In this paper, we present an approach for deriving both the process–structure and structure–property correlations based on the diffuse-interface approach. Herein, we derive process–structure correlations using phase-field simulations based on the Cahn–Hilliard formalism for modeling phase-separation in ternary systems where a third component that acts as an acceptor is added to a binary OPV. This leads to structures that can be classified as donor–acceptor–acceptor. Thereafter, we derive the structure–property correlations again using a diffuse interface approach for deriving the electronic properties such as the efficiency, fill-factor, short-circuit current, and the open-circuit voltages for the simulated microstructures involving the three phases in the active layer. Thus, using a combination of the process–structure and structure–property correlations, optimal compositions can be determined. Further, in order to expedite the theoretical prediction, a robust and elegant data analytics model is built using dimensionality reduction techniques.
Scalable wafer-to-fiber transfer method for lab-on-fiber sensing
Authors: Picelli L. , van Klinken A. , Lindgren G. , Hakkel K. D. , Pagliano F. , Fiaschi N. , Sersic-Vollenbroek I. , van Veldhoven P. J. , van der Heijden R. W. , Fiore A.
Published: October 2020

We present an efficient and flexible method to realize micro- and nano-optical structures on the tip of optical fibers. We demonstrate this approach for a fiber-tip sensor consisting of a photonic crystal (PhC) structure in a semiconductor membrane on the cleaved facet of a telecom fiber. The PhC structure is fabricated on a wafer by lithography and etching and then transferred to the fiber facet by a simple mechanical pickup process through an opening in the substrate, without the need for adhesives or a micromanipulator. Due to its reliability, scalability, and the use of wafer-scale fabrication methods, this process increases the possibilities for fiber-tip applications at the industrial level. With the fabricated fiber tip sensors, we demonstrate sensing of the refractive index and temperature, with resonance wavelength shifts of 120 nm/RIU and 95 pm/K, respectively.
Producing a magnetized low energy, high electron charge density state using a split cathode
Authors: Leopold J. G. , Krasik Ya. E. , Bliokh Y. P. , Schamiloglu E.
Published: October 2020

When a magnetized annular relativistic electron beam propagating in a conducting tube carries a charge higher than the space charge limit, it can stabilize at a lower energy and higher density state. Such a charge distribution can be used as an electron source in high power microwave devices, a relativistic magnetron in particular, and in other applications. The limiting current transmitted by the beam decreases in tubes with larger radii, so in a tube with a radial transition from a small to large radius, the current can over-inject the downstream tube. This can start a dynamical process which stabilizes as a high density state. The same effect can be achieved by increasing the magnetic field in a magnetic mirror-like scheme or by adding a slowing down potential in the electron beam's route. Here, we propose a simpler, more practical way to produce such a dense state by splitting the cathode into an emitter and a reflector. This scheme is tested in simulation and experiment.
Tubular optical microcavities based on rolled-up photonic crystals
Authors: Briche Rémi , Benamrouche Aziz , Cremillieu Pierre , Regreny Philippe , Leclercq Jean-Louis , Letartre Xavier , Danescu Alexandre , Callard Ségolène
Published: October 2020

The self-rolling of micro-structured membranes via the stress-engineering method opens new ways to create 3D photonic micro-objects with original designs and optical properties. This article validates this approach by producing 3D hollow micro-resonators based on rolled-up 2D photonic crystal membrane mirrors, capable of trapping light in 3D and in air. We fabricated the 3D tubular microresonators with 10 μm–20 μm diameters by rolling photonic crystal membranes using stress-engineering technique on the prestressed InGaP/InP bilayer. We also added a design feature to lift the microtubes vertically and facilitate optical measurements, but also to attach the structures to the substrate. The dispersion of the planar 2D photonic crystal membrane was optimized to exhibit high reflectivity (>95%) at normal incidence over a large spectral band (100 nm) in the near-infrared domain (1.5 μm–1.6 μm). The cylindrical cavity model and numerical simulations predicted the presence of quasi-pure radial cavity modes with a strong concentration of light over nearly 3% of the photonic microtubes’ cross section. We demonstrated experimentally the presence of those modes through scanning near-field optical microscopy measurements. Using a bowtie nanoantenna, we selectively detected and mapped transverse electric modes in the hollow core of photonic microtubes. Spatially resolved cartographies allowed for the identification of the modes in good agreement with theoretical predictions. This work brings theoretical and experimental proof of concept of light cages based on rolled-up photonic crystal membranes. It also opens the path to the realization of original photonic microstructures as combinations of a specific photonic crystal design and a targeted 3D form.
Strain-induced hierarchical ripples in MoS2 layers investigated by atomic force microscopy
Authors: Hussain Sabir , Xu Rui , Xu Kunqi , Lei Le , Meng Lan , Zheng Zhiyue , Xing Shuya , Guo Jianfeng , Dong Haoyu , Liaqat Adeel , Iqbal Muhammad Ahsan , Li Yan Jun , Sugawara Yasuhiro , Pang Fei , Ji Wei , Xie Liming , Cheng Zhihai
Published: October 2020

Strain engineering plays a vital role in controlling the physical properties of two-dimensional (2D) materials. However, the nanomechanical behavior of atomically thin 2D crystals under strain has not been completely understood. Here, strain-induced hierarchical ripple nanostructures in triangular MoS2 flakes were investigated by advanced atomic force microscopy and optical spectral measurements. The hierarchical nanoripples exhibited a threefold radial pattern, and their mechanical, electronic, and optical spectra characteristics were significantly modified due to the suffering from large tensile strain. Structure evolution of these hierarchical nanoripples was further discussed based on the geometry and thickness of MoS2 flakes, and we attributed the curtain effect at the limit of a single atomic layer. Our study will be beneficial in designing nanomechanical structures and prototype electromechanical devices with 2D materials.