Academic literature on the topic 'Novel Haïti'
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Journal articles on the topic "Novel Haïti"
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Zhang, Lei, Weimin Long, Dong Du, Zhibin Fan, Chao Jiang, and Xia Jin. "A Novel Diamond/AlSi Composite Coating on Ti-6Al-4V SubStrate Made by Ultrasonic-Assisted Brazing." Coatings 13, no. 9 (September 13, 2023): 1596. http://dx.doi.org/10.3390/coatings13091596.
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Ultrasonic-assisted brazing (UAB) technology has been introduced to prepare the diamond/AlSi composite coating on Ti-6Al-4V substrate. The microstructure and wear properties of the coating were studied. The results showed that AlSi filler metal had a certain spreading and climbing phenomenon on the diamond surface, indicating a significant improvement in wettability between AlSi filler metal and diamond by ultrasonic-assisted brazing. Under ultrasound action, the microstructure of AlSi brazing alloy was greatly refined, and the Ti atoms in the Ti-6Al-4V substrate diffused to the interface between diamond and AlSi brazing alloy and formed TiC on diamond particles. There was no thermal damage to diamond particles when the brazing temperature was 750 °C. UAB improved the microhardness of the coating alloy matrix due to the increasing quantity and distribution range of TiAl3 as reinforced particles but had no obvious effect on the microhardness of the Ti-6Al-4V substrate. The wear resistance of Ti-6Al-4V substrate with diamond/AlSi composite coating was promoted due to the dense diamond particles, the formed TiC on diamond particles, and the increase in microhardness of the alloy matrix of diamond/AlSi coating under ultrasound action.
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Gao, Jie, Lingfan Zhang, Xin Liu, and Wenqing Zhang. "Hierarchically structured, well-dispersed Ti4+ cross-linked chitosan as an efficient and recyclable sponge-like adsorbent for anionic azo-dye removal." RSC Advances 6, no. 108 (2016): 106260–67. http://dx.doi.org/10.1039/c6ra24446g.
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One novel of sponge-like Ti4+ cross-linked chitosan (SL-TiCs) was prepared. The SL-TiCs had multiply nano-layer twisted sheets and high content of Ti4+, which can provide plenty channels for mass transfer and active sites for dyes adsorption.
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Kunheen, Khayas Omer, MC Tomichan, Rajeev PB, and Adarsh Krishna K. Bhat. "Novel Adaptation of Suture Bridge Technique for Greater Tuberosity Redisplacement Post ORIF With PHILOS- A Technical Note." Trauma International 6, no. 2 (2020): 15–18. http://dx.doi.org/10.13107/ti.2020.v06i02.107.
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Isolated Greater tuberosity (GT) fractures still pose a therapeutic challenge due to the wide variety of treatment options and lack of proper comparative studies on outcome. Plating still remains a valid option but has several unfavorable effects. One among them is redisplacement of tuberosity postoperatively especially in cases with comminution which may easily be missed in regular plain radiographs. Conventional techniques of fixation may remain insufficient in such scenarios. We hereby propose an adaptation of a described technique, in a 45-year-old male presenting with redisplacement of GT post plate fixation. Open double-row suture bridge construct was used to fix the displaced fragment maintaining the plate insitu and the patient had an excellent functional and radiological outcome on follow-up. Keywords: Greater tuberosity fracture; Comminution; Double-row fixation; Suture anchor; Suture Bridge technique; PHILOS; Redisplacement.
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Yang, Jitao. "A novel Method for Sternal Fixation in Cardiac Surgery: Initial Experience." Angiology & Vascular Surgery 7, no. 2 (July 22, 2022): 1–5. http://dx.doi.org/10.24966/avs-7397/100096.
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Objectives: To investigate whether the Ni-Ti-shaped memory alloy embracing plate is an effective treatment for post -sternotomy complications and to see if it can improve the mechanical stability of sternal closure and to evaluate its initial outcome. Methods: One-hundred twenty patients from January 2012 through December 2015 underwent sternal fixation with the Ni-Ti-shaped memory alloy embracing plate in cardiac sugery. Sternal healing was evaluated by physical examination, wound healing complications and the Computed Tomography (CT) showings of coaptation the sternal halves. The pain scores were recorded preoperatively and postoperatively on day 3 to 7, discharge, 4 weeks, and 3 and 6 months. Results: The patients with Ni-Ti-shaped memory alloy embracing plate fixation had less postoprative comlications, such as fat liquefication, mediastinitis, sternal dehiscenc. The postoperative pain scores were significantly lower in patients with sternal fixation of embracing plates than that with wire cerclage. The life quanlity was imporoved in embracing plate fixation patients. Conclusion: The Ni-Ti-shaped memory alloy embracing plate significantly improved the sternal stability closure and life quanlity and reduced postoperative pain in cardiac surgery.
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Zhang, Ningbo, Boyu Ju, Taiqing Deng, Sen Fu, Cungao Duan, Yiwei Song, Yijun Jiang, et al. "Effect of Volume Fraction of Reinforcement on Microstructure and Mechanical Properties of In Situ (Ti, Nb)B/Ti2AlNb Composites with Tailored Three-Dimensional Network Architecture." Materials 15, no. 24 (December 19, 2022): 9070. http://dx.doi.org/10.3390/ma15249070.
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The mechanical properties of (Ti, Nb)B/Ti2AlNb composites were expected to improve further by utilizing spark plasma sintering (SPS) and inducing the novel three-dimensional network architecture. In this study, (Ti, Nb)B/Ti2AlNb composites with the novel architecture were successfully fabricated by ball milling the LaB6 and Ti2AlNb mixed powders and subsequent SPS consolidation. The influence of the (Ti, Nb)B content on the microstructure and mechanical properties of the composites was revealed by using the scanning electron microscope (SEM), transmission electron microscopy (TEM) and electronic universal testing machine. The microstructural characterization demonstrated that the boride crystallized into a B27 structure and the α2-precipitated amount increased with the (Ti, Nb)B increasing. When the (Ti, Nb)B content reached 4.9 vol%, both the α2 and reinforcement exhibited a continuous distribution along the prior particle boundaries (PPBs). The tensile test displayed that the tensile strength of the composites presented an increasing trend with the increasing (Ti, Nb)B content followed by a decreasing trend. The composite with a 3.2 vol% reinforcement had the optimal mechanical properties; the yield strengths of the composite at 25 and 650 °C were 998.3 and 774.9 MPa, showing an 11.8% and 9.2% improvement when compared with the Ti2AlNb-based alloy. Overall, (Ti, Nb)B possessed an excellent strengthening effect and inhibited the strength weakening of the PPBs area at high temperatures; the reinforcement content mainly affected the mechanical properties of the (Ti, Nb)B/Ti2AlNb composites by altering the α2-precipitated amount and the morphology of (Ti, Nb)B in the PPBs area. Both the continuous precipitation of the brittle α2 phase and the agglomeration of the (Ti, Nb)B reinforcement dramatically deteriorated the mechanical properties.
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Chen, Tijun, Libo Geng, He Qin, and Min Gao. "Core-Shell-Structured Particle Reinforced A356 Matrix Composite Prepared by Powder-Thixoforming: Effect of Reheating Temperature." Materials 11, no. 9 (September 13, 2018): 1718. http://dx.doi.org/10.3390/ma11091718.
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A novel core-shell-structured Ti-(Al-Si-Ti) particle (Ti-(Al-Si-Ti)p) reinforced A356 matrix composite was fabricated by a new method, powder thixoforming, which combines the merits of both powder metallurgy and semisolid thixoforming. The effects of reheating temperature on the microstructure and tensile properties of the resulting composite were investigated. The results indicated that the thickening of the Al-Si-Ti compound shells, with rising the reheating temperature, significantly enhanced the strengthening role, but the fracture and peeling of the shells, at higher than 600 °C, impaired the strengthening effect. The composite formed at 600 °C had a favorable tensile elongation of 8.3% besides high tensile strengths. During tensile testing, the Ti@(Al-Si-Ti)p frequently fractured across the Ti cores and occasionally cracked around the Ti cores, but preferentially fractured between the outer cracked shells and the inner cores for the composites thixoformed at higher than 600 °C. The delayed formation of cracks in the Ti-(Al-Si-Ti)p and the small size of the cracks contributed to ductility improvement. The MSL model, modified according to the Ti@(Al-Si-Ti)p characteristics, was essentially suitable for predicting the yield strength of such composites. The largest contribution to the strength was resulted from solid solution strengthening of Ti element, but the strengthening role from geometrically necessary dislocations was significantly improved as the reheating temperature rose from 590 °C to 600 °C.
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Li, Zhi, Guangbo Che, Wei Jiang, Lihui Liu, and Hairui Wang. "Visible-light-driven CQDs@MIL-125(Ti) nanocomposite photocatalyst with enhanced photocatalytic activity for the degradation of tetracycline." RSC Advances 9, no. 57 (2019): 33238–45. http://dx.doi.org/10.1039/c9ra05600a.
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A novel CQDs@MIL-125(Ti) photocatalyst had been synthesized by a facile solvothermal process for the degradation of TC. The possible degradation mechanism was proposed based on the active species trapping experiments.
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Ewid, Mohammed, Mervat Naguib, Ali Alamer, Hala El Saka, Sharifa Alduraibi, Abdullah AlGoblan, and Elzaki Ahmed. "Updated ACR Thyroid Imaging Reporting and Data Systems in risk stratification of thyroid nodules: 1-year experience at a Tertiary Care Hospital in Al-Qassim." Egyptian Journal of Internal Medicine 31, no. 4 (December 2019): 868–73. http://dx.doi.org/10.4103/ejim.ejim_143_19.
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Abstract Background Thyroid imaging reporting and data system (TI-RADS) is assessment of risk stratification of thyroid nodules, using a score. A novel ACR (American College of Radiology) TI-RADS has been recently suggested by American College of Radiology. But, the utility of ACR TI-RADS in risk stratification for thyroid lesion needs further evaluation. Aim Of this study was to evaluate ACR TI-RADS classification in discriminating benign and from other thyroid lesions as detected by fine needle aspiration cytology (FNAC). Methods This retrospective study included all patients referred to our institute for FNAC of a thyroid nodule over 1 year. Thyroid nodules were categorized according to the 2017 ACR TI-RADS. Ultimately, efficacy of ACR TI-RADS in differentiating benign from non-benign nodules was assessed using ROC curve, cross-tabulation, and Chisquare tests. According to the results of FNAC, nodules were classified into 2 groups; benign lesions (Bethesda II) and malignant lesions (Bethesda IV, V). Results The percentages of Bethesda IV and V lesions defined in our ACR-TIRADS were as follows: ACR TI-RADS 1, 2 (0%), ACR TI-RADS 3 (4%), ACR TI-RADS 4 (6.6%), and ACR TI-RADS 5 (22.6%). ROC curve analysis for ACR TI-RADS to differentiate benign from non-benign pathology showed (AUC 0.60, 95% CI: 0.505–0.713). ACR TI-RADS had sensitivity, specificity, positive predictive value and negative predictive value 75%, 62.35 %, 15.7%, 96.3% respectively. Conclusion Differentiation between benign and malignant thyroid lesion can be suggested from the ultrasound based ACR TI-RADS system. FNAC might be deferred in patients having ACR TI-RADS 1 and 2.
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Sun, Yu, Qingping Liu, Zhenglei Yu, Luquan Ren, Xin Zhao, and Jincheng Wang. "Study on Osseointegration Capability of β-Type Ti–Nb–Zr–Ta–Si Alloy for Orthopedic Implants." Materials 17, no. 2 (January 19, 2024): 472. http://dx.doi.org/10.3390/ma17020472.
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Osseointegration is the basic condition for orthopedic implants to maintain long-term stability. In order to achieve osseointegration, a low elastic modulus is the most important performance indicator. It is difficult for traditional titanium alloys to meet this requirement. A novel β-titanium alloy (Ti–35Nb–7Zr–5Ta)98Si2 was designed, which had excellent strength (a yield strength of 1296 MPa and a breaking strength 3263 MPa), an extremely low elastic modulus (37 GPa), and did not contain toxic elements. In previous in vitro studies, we confirmed the good biocompatibility of this alloy and similar bioactivity to Ti-6Al-4V, but no in vivo study was performed. In this study, Ti-6Al-4V and (Ti–35Nb–7Zr–5Ta)98Si2 were implanted into rabbit femurs. Imaging evaluation and histological morphology were performed, and the bonding strength and bone contact ratio of the two alloys were measured and compared. The results showed that both alloys remained in their original positions 3 months after implantation, and neither imaging nor histological observations found inflammatory reactions in the surrounding bone. The bone–implant contact ratio and bonding strength of (Ti–35Nb–7Zr–5Ta)98Si2 were significantly higher than those of Ti-6Al-4V. The results confirmed that (Ti–35Nb–7Zr–5Ta)98Si2 has a better osseointegration ability than Ti-6Al-4V and is a promising material for orthopedic implants.
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Wang, Guangshun, Karen M. Watson, Alan Peterkofsky, and Robert W. Buckheit. "Identification of Novel Human Immunodeficiency Virus Type 1-Inhibitory Peptides Based on the Antimicrobial Peptide Database." Antimicrobial Agents and Chemotherapy 54, no. 3 (January 19, 2010): 1343–46. http://dx.doi.org/10.1128/aac.01448-09.
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ABSTRACT To identify novel anti-HIV-1 peptides based on the antimicrobial peptide database (APD; http://aps.unmc.edu/AP/main.php ), we have screened 30 candidates and found 11 peptides with 50% effective concentrations (EC50) of <10 μM and therapeutic indices (TI) of up to 17. Furthermore, among the eight peptides (with identical amino acid compositions but different sequences) generated by shuffling the sequence of an aurein 1.2 analog, two had a TI twice that of the original sequence. Because antiviral peptides in the database have an arginine/lysine (R/K) ratio of >1, increases in the Arg contents of amphibian maximin H5 and dermaseptin S9 peptides and the database-derived GLK-19 peptide improved the TIs. These examples demonstrate that the APD is a rich resource and a useful tool for developing novel HIV-1-inhibitory peptides.
Book chapters on the topic "Novel Haïti"
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Ouadah, Ouahiba. "Titanium Aluminide Coating: Structural and Elastic Properties by DFT Approach." In Transition Metal Compounds - Synthesis, Properties, and Application. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97409.
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The stability, elastic and electronic properties of titanium aluminide compounds have been systematically studied by the first-principles calculation. The calculated lattice parameters are consistent with the results found in the literature. The three Ti-Al binary compounds are thermodynamically stable intermetallics depending on their negative formation enthalpy. It has been found that the Ti-Al binary compounds are composed of both metallic and covalent bonds. Elastic properties revealed that these alloys are more resistant to deformation along the a- and c-axis. Besides, the (001)[100] deformation would be easier than (010)[100] deformation for these alloys. The results found in this chapter give a reliable reference for the design of novel Ti-Al binary alloys.
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Urossha, S. "MXenes for Nanophotonics." In bookTitle Recent Advances and Allied Applications of Mxenes, 48–80. Materials Research Forum LLC, 2024. http://dx.doi.org/10.21741/9781644902875-3.
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Considerable attention has been paid to Mxenes which is a novel group of two-dimensional materials. Exceptional 2D layered microstructures make this family quite attractive for potential applications in a number of photoelectric applications along with their nonlinear optical and short electronic transport characteristics. This 2D group of materials comprises of transition metal carbides, carbonitrides, and nitrides having formula Mn+1Xn (where M = Sc, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, etc., and X = C and/or N). Owing to some unmatched features of Mxenes like hydrophilic surfaces and high conductivities (~6000–8000 S/cm), these can be implemented in potential applications such as catalysis, energy storage, and field effect transistors etc.
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Salih Mahdi Alkhafaji, Falih, Wan Zuha Wan Hasan, Nasri Sulaiman, and Maryam Mohd. Isa. "A Novel PID Robotic for Speed Controller Using Optimization Based Tune Technique." In Computational Optimization Techniques and Applications. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95892.
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One of the most significant issue of proportional integral derivative (PID) controller is the efforts to optimize coefficient gains. Based on survey, massive tuning methods were proposed to resolve this problem but there is little pay attention to maximize minimization time response significantly. This study proposed a novel technique to maximize optimization PID gains for the DC motor controller by combining both proper tuning method with signal input signal output (SISO) optimization toolbox using optimization based tune (OBT) techniques, that could be utilized for the highest precision controller. The comparative study has been carried out by applying five different tuning methods to obtain a proper tuning controller, then to be combined with SISO optimization toolbox. The utilized tuning methods are Robust Auto tune (RAT), Ziegler–Nichols (Z-N), Skogestad Internal Model Control (SIMC), Chien Hroues Reswick (CHR), and Approximate M-Constrained Integral Gain Optimization (AMIGO). The performance of each tuning methods based OBT are analyzed and compared using MATLAB/SISO tool environment, where the efficiency has been assessed on a basis of time response characteristics (Ti) in terms of dead time (td), rise time (tr), settling time (ts), peak time (tp) and peak overshoot (Pos). The simulation results of AMIGO based proposal show a significant reduction time response characteristic to be measured in the Microsecond unit (μs). The novelty feature of the proposed is that provides superior balancing between robustness and performance. This study has been completely rewritten to account for the robotic controller development that has been taken place in the last years.
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Ghosh, Sukanya, and Lintu Rajan. "II-VI Semiconductor-based Thin-Film Transistor Sensor for Room Temperature Hydrogen Detection From Idea to Product Development." In Nanoelectronics Devices: Design, Materials, and Applications (Part I), 182–207. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815136623123010010.
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Implementing gas sensors incorporating nanoelectronic devices to detect pollution and improve the safety control of industrial, medical, and domestic sectors has opened up a novel world with immense interest. As a promising renewable energy carrier and a potential replacement for fossil fuels, there is the paramount importance of hydrogen gas storage at extensive facilities worldwide. The sustainable production of hydrogen is increasing owing to its enormous energy per mass of any fuel. Nevertheless, due to its extreme flammability, simple and highly accurate sensors with promising sensing materials are required to detect the slightest traces of timely leak detection for developing a hydrogen economy. Various hydrogen detectors already exist, but expensive cost, large size, sluggish response, and high temperature limit their potential for widespread applications. The integral objective of the present chapter is to focus on a systematic investigation of Pd-Ti/ZnO Schottky TFT-based room temperature hydrogen sensors excluding any heating element. With high chemical and thermal stability, ZnO is a promising candidate for sensors in a hazardous atmosphere. The developed sensor exhibited room temperature detection with a maximum response of 33.8% to 4500 ppm H2 in dry air. The selectivity analysis toward H2 in the presence of other reducing and oxidizing gas species has also been investigated to ensure the real-time applicability of the sensor. Reliable operation of the sensor in a wide range of 500 ppm to 4500 ppm H2 has been confirmed from the linear behavior of the sensor. The hydrogen sensing mechanism of the proposed sensor in terms of Schottky barrier height reduction at the interface of Pd-Ti/ZnO has also been detailed in this chapter. Room temperature detection of the hydrogen sensor presented here competes favorably with the existing studies. This study can be extended in exploring new routes to realize hydrogen sensing applications at room temperature for commercialization with precise control over film thickness and target gas concentrations.
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Jiang, Wan, Jianfeng Zhang, and Lianjun Wang. "Spark Plasma Sintering of MAX Phases and Their Related Composites." In MAX Phases and Ultra-High Temperature Ceramics for Extreme Environments, 1–33. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-4066-5.ch001.
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With the combined merits of both metals and ceramics, including good electrical and thermal conductivity, ready machinability, exceptional damage tolerance, light weight, high rigidity, etc., the ternary layered MAX compounds have attracted much attention in the world. For the synthesis and consolidation of MAX phases, the relatively novel spark plasma sintering (or SPS in short) represents a very competitive technique for its high efficiency and energy saving. Since 2000’s, SPS has been extensively used for this propose, especially in Ti3SiC2 and Ti3SiC2-based composites. The present general results indicate that Ti/Si/TiC is the most appropriate powder mixture and Al is a good aid for the synthesis of high purity Ti3SiC2 by SPS. Various Ti3SiC2-based composites have also been consolidated by SPS and the related properties were improved, such as hardness, strength, fracture toughness and conductivity. It is very important to notice that, Ti3SiC2 phase can also be in situ synthesized in its composites as the commercial Ti3SiC2 powder is hardly available. A few other MAX phases have also been synthesized and consolidated by SPS in one step using various powder mixtures. However, much work should be done to clarify the synthesis mechanism and various processing windows for MAX phases by SPS technique. Lowering the fabrication cost and finding appropriate applications of MAX phases are also eagerly expected.
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Shakeel, R. "Fundamental Concepts of Topological Insulators." In Materials Research Foundations, 1–20. Materials Research Forum LLC, 2024. http://dx.doi.org/10.21741/9781644902851-1.
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The notion of topological insulators was first introduced to explain the concept of Quantum Hall Effect. The Quantum Hall State (QHS) does not disrupt symmetries but showed fundamental properties (like quantized Hall conductivity, the number of conducting edge-mode) that are not affected by smooth changes in different material parameters and are not subject to change if the system goes through the quantum phase-transition. A topological insulator (TI) just like an ordinary insulator has a large energy gap that is separating the highest-filled electronic band from the lowest empty-band. However, a topological insulator's surface must have gapless electronic states which are protected by the time-reversal symmetry (TRS). Like QHS, having distinctive gapless chiral edge-states on the surface or the edge-states of the topological insulators (TIs) are topologically shielded and reveal conducting states having properties that are unlike any other known 1D and 2D electronic systems. Strong spin-orbit interactions under the conservation of time-reversal symmetry (TRS) are the driving force behind these substances. Moreover, Topological insulators (TIs) were revealed experimentally for the first time in 2007 by the consideration of the condensed-matter physics community which become fully focused on a novel category of materials. The 3D topological insulator's new qualities could result in some fascinating applications because they are very common semiconductors and their topological properties can withstand high temperatures. Hence, Topological insulators (TIs) are those materials that are electrically inert in bulk but can carry out electricity due to their topologically protected electronic edge-state as well as surface states.
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Taber, Douglass. "Reactions of Alkenes." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0022.
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One of the most powerful of alkene transformations is enantioselective epoxidation. Tsutomu Katsuki of Kyushu University has developed (Angew. Chem. Int. Ed. 2007, 46, 4559) a Ti catalyst that with H2O2, selectively epoxidized terminal alkenes with high ee. The same catalyst converted a Z 2-alkene such as 3 into the epoxide. This is significant, because such epoxides are opened with nucleophiles selectively at the less congested center. Novel procedures for alkene functionalization have been put forward. Philippe Renaud of the University of Berne has developed (Adv. Synth. Cat. 2008, 350, 1163) a simple protocol for terminal halogenation, based on catalyzed addition of catecholborane, followed by free radical substitution. Sulfides and selenides were also prepared. H. Zoghlami of the Faculty of Sciences of Tunis has devised (Tetrahedron Lett. 2007, 48, 5645) an oxidative sulfinylation, converting a terminal alkene 7 to the sulfide 8. M. Christina White of the University of Illinois (J. Am. Chem. Soc. 2008, 130, 3316) and Guosheng Liu of the Shanghai Institute of Organic Chemistry (Angew. Chem. Int. Ed. 2008, 47, 4733) independently developed Pd catalysts for the oxidation of a terminal alkene 9 to the terminal allylic amine 10. Shannon S. Stahl of the University of Wisconsin-Madison has established (Organic Lett. 2007, 9, 4331) conditions for the complementary transformation of a terminal alkene 11 to the enamide 12. Douglas B. Grotjahn of San Diego State University has optimized (J. Am. Chem. Soc. 2007, 129, 9592) Ru-catalyzed alkene (“zipper”) migration, effecting the conversion of 13 to 14 and of 15 to 16 . There have been several new observations on alkene cleavage. Marcus A. Tius of the University of Hawaii and Bakthan Singaram of the University of California, Santa Cruz have found (Tetrahedron Lett. 2008, 49, 2764) that epoxides such as 17 are cleaved directly by NaIO4, providing a simple alternative to ozonolysis. Rolando A. Spanevello of the Universidad Nacional de Rosario has extended (Tetrahedron 2007, 63, 11410) unsymmetrical ozonolysis to highly substituted norbornene derivatives such as 19, observing 20 as the only product. Patrick H. Dussault of the University of Nebraska–Lincoln has established (J. Org. Chem. 2008, 73, 4688) that alkene ozonolysis in wet acetone delivered the ketone or aldehyde directly, without reductive workup.
Conference papers on the topic "Novel Haïti"
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Zhang, Yi, and Gary J. Cheng. "Multilayer Laser Sintering of HAp/Ti Nanoparticles Onto Metallic Implants." In ASME 2009 International Manufacturing Science and Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/msec2009-84089.
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Novel methodology of laser sintering of mixture of mixture of bio-ceramics and metallic nanoparticles on metallic implants is introduced in current work. Feasibility of this method is demonstrated using a multiphysics numerical simulation. Treating laser beam as electromagnetic (EM) wave, EM module is coupled with heat transfer (HT) module. The EMHT scheme analyzes the interaction between laser-nanoparticles which ends up with temperature raise within the sample. As a demonstration, HAp and Ti nanoparticles are employed to be sintered on titanium substrate. Processing parameters such as laser power, beam radius, scan speed, and layer thickness are studied, and correlation between these parameters and final temperature is presented. Effects of mixing ratio and nanoparticle size are also examined. Considering effects of mixing ratios and particle sizes, the following coating scheme is proposed for future experiments: varying HAp concentration from 100% to 0% at 10% intervals from coating surface to coating/substrate interface, and meanwhile, varying particle diameters from 500 nm to 100 nm at 100 nm intervals.
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Khor, K. A., Y. W. Gu, Y. Li, C. H. Quek, V. J. P. Lim, and P. Cheang. "Novel Bioactive Composites by Thermal Spray Process." In ITSC 2000, edited by Christopher C. Berndt. ASM International, 2000. http://dx.doi.org/10.31399/asm.cp.itsc2000p0625.
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Abstract This paper compares two types of hydroxyapatite (HA) composite coatings, HA/Ti-6Al-4V and HA/Y-ZrO2. The powders used in the study were prepared using a slurry process then deposited by plasma spraying. The resulting coatings were characterized based on their microstructure, mechanical properties, and biocompatibility. Both composite coatings performed better than pure HA coatings in tensile adhesion and indentation tests. Testing also revealed that the HA/Y-ZrO2 coatings had favorable strength and fracture toughness and that the HA/Ti-6Al-4V coatings had good affinity to living tissue and sufficient mechanical strength.
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D. Lefler, Hyrum, Mari Gilmore, and Z. Zak Fang. "Sustainability of a Novel Low-Cost Process for Making Spherical Titanium Alloy Powders for Additive Manufacturing." In Euro Powder Metallurgy 2023 Congress & Exhibition. EPMA, 2023. http://dx.doi.org/10.59499/ep235764483.
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Titanium (Ti) is often a preferred metal for its superior strength-to-weight ratio, corrosion resistance, bio-compatibility, and its high melting point. Despite these advantages, titanium’s high cost and high environmental burden have relegated its use almost exclusively to niche, high-dollar applications such as the aerospace and medical sectors. The rise of additive manufacturing has brought with it an increasing demand for low-cost and sustainable spherical Ti-6Al-4V (Ti64) metal powders. Current commercial spherical Ti64 powders are produced through melt atomization techniques, which are not suitable for recycling Ti scrap with high oxygen content, and thus are not adequate for achieving corporate and consumer sustainability goals. A novel technique for production of such powders from high oxygen Ti scraps has been developed using Hydrogen Assisted Metallothermic Reduction (HAMR) technology to minimize oxygen content. This approach has the potential to substantially decarbonize the global titanium metal industry.
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Brzezinski, T. A., S. Grenier, M. E. Smagorinski, and G. E. Kim. "Vacuum Plasma Spray Deposition of Spherical Plasma Atomized Ti-6AI-4V." In ITSC 2000, edited by Christopher C. Berndt. ASM International, 2000. http://dx.doi.org/10.31399/asm.cp.itsc2000p0935.
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Abstract The growing need for new materials and material combinations with superior properties for severe service applications has led to the development of near net-shape forming techniques for certain materials, such as superalloys, refractory metals (Ta, W, and Mo) and highly reactive metals (Ti and its alloys). Vacuum plasma spray (VPS) was used to produce dense Ti-6Al-4V deposits for mechanical properties evaluation. Spherical Ti-6Al-4V powder, produced by Plasma Atomization (PA), a novel patented powder fabrication technique, was used as the starting powder. Plasma atomized Ti-6Al-4V powder characteristics include: high purity, tight particle size range, highly spherical with no attached satellites, and excellent flowability. The resulting as-sprayed Ti-6Al-4V deposits were dense and low in oxygen content. Thermal treatment was conducted after spraying in order to improve the structure and the properties of the spray formed material. The mechanical properties of the material, including tensile strength, elongation and hardness, in both the as-sprayed and the heat treated conditions were compared. The mechanical properties of these preliminary VPS Ti-6Al-4V specimens indicate that the combination of high purity starting powder and controlled environment deposition can be used to produce dense spray formed Ti-6Al-4V structures with properties comparable to those of cast or sintered powder metallurgy parts.
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Rathgeber, David, Erick Johnson, Peter Lucon, Ryan Anderson, Burt Todd, Jerome Downey, and Lee Richards. "A Novel Approach to Determining Carrying Capacity Index Through Incorporation of Hole Size and Pipe Rotation." In SPE Western Regional Meeting. SPE, 2023. http://dx.doi.org/10.2118/212985-ms.
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Abstract Current API RP13D guidelines outline 3 methods for determining hole-cleaning efficiency based on wellbore angle. Method 1, used in low-angle wellbores (<30°) compares cuttings slip velocity with annular velocity to determine a transport ratio and cuttings concentration. Method 2, also used for low-angle wellbores (<30°) derives a carrying capacity index (CCI) based on bulk annular velocity, fluid density and power-law rheology. Method 3, used in high-angle wellbores (<30°) derives a transport index (TI) based on fluid rheology, density, and flow rate. TI is then plotted on an empirically derived chart (Luo et al., 1992, 1994) to determine maximum allowable rate of penetration (ROP) that should ensure efficient hole cleaning. Although these methods are considered recommended practices by API, Method 3 (TI) is based on an outdated study (Luo et al., 1992) with limited scope (one flow loop, one field test). Additionally, this method neglects the importance of drill pipe rotation and pipe eccentricity in cuttings transport efficiency, which has been proven to be a factor in other studies (Akhshik et al., 2015; Sanchez et al., 1997b). This paper highlights the shortcomings of current API standards and identifies what effects contributing factors such as pipe eccentricity and drill pipe rotation rates may have on cuttings transport efficiency. Further, this paper discusses the impact pipe-to-hole area ratio and wellbore flow area have on the effects of drill pipe rotation and flow channeling. Five horizontal wellbores were modeled using Siemens Star CCM+ Computational Fluid Dynamics (CFD) software, with bottom-eccentric 4 ½″ drill pipe placement, in annular diameters of 6¾″, 7 ⅞″, 8 ⅜″ 8 ½″ and 8 ⅝″. Additionally, one bottom-eccentric 5″ drill pipe in an 8 ¾" wellbore was modeled to compare identical pipe-to-hole area ratios with different flow areas. Simulations were run with drill pipe rotation speeds increasing from 0 to 180 RPM, in 30 RPM increments. In order to determine the impact fluid rheology has on flow channel development, both medium density oil-based muds and light density water-based muds were modeled and compared. Bulk annular flow velocity was set to 100 ft/min, to maximize the observable effects of drill pipe rotation. Bulk average velocity was calculated from cross sectional area, determining both annular velocity (velocity parallel to wellbore) and absolute velocity (fluid velocity magnitude regardless of direction). The resultant velocity profiles were used as the annular velocity component in API CCI and TI calculations and compared to bulk annular velocity. In addition to observing fluid velocity for CCI and TI calculations, changes in effective viscosity from the onset of pipe rotation was also analyzed to determine changes in wellbore parameters that may affect cuttings transport.
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Ding, Hongtao, and Yung C. Shin. "Dislocation Density-Based Grain Refinement Modeling of Orthogonal Cutting of Commercially Pure Titanium." In ASME 2011 International Manufacturing Science and Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/msec2011-50220.
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Recently, machining has been exploited as a means for producing ultra-fine grained (UFG) and nanocrystalline microstructures for various metal materials, such as aluminum alloys, copper, stainless steel, titanium and nickel-based super alloys, etc. However, no predictive, analytical or numerical work has ever been presented to quantitatively predict the change of grain sizes during machining. In this paper, a dislocation density-based viscoplastic model is adapted for modeling the grain size refinement mechanism during machining by means of a finite element based numerical framework. A novel Coupled Eulerian-Lagrangian (CEL) finite element model embedded with the dislocation density subroutine is developed to model the severe plastic deformation and grain refinement during a steady-state cutting process. The orthogonal cutting tests of a commercially pure titanium (CP Ti) material are simulated in order to assess the validity of the numerical solution through comparison with experiments. The dislocation density-based material model is calibrated to reproduce the observed material constitutive mechanical behavior of CP Ti under various strains, strain rates and temperatures in the cutting process. It is shown that the developed model captures the essential features of the material mechanical behavior and predicts a grain size of 100–160 nm in the chips of CP Ti at a cutting speed of 10 mm/s.
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Fujiwara, T., A. Watanabe, and H. Mori. "Uniformity of driving voltage in Ti:LiNbO3 waveguide devices." In Integrated Photonics Research. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/ipr.1990.tud6.
Full textAbstract:
One of the most important issues in integrated-optic applications of Ti:LiNbO3 waveguides is the uniformity of driving voltage among device elements fabricated on a single chip. In LiNbO3-based matrix switches using directional coupler switch elements, scatter of the switching voltage has been reported.1,2 We report on a novel method of measuring a spatial variation of the electro-optic effect on a number of positions on x- and z-cut LiNbO3 substrates in Ti-diffused form.
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Wickramasinghe, K. C., and Hiroyuki Sasahara. "Ultra-Fine Bubbles (UFB) Inserted Novel Coconut Oil Based Metal Working Fluid (MWF) As a Sustainable Lubricant for Turning of Ti-6Al-4V." In ASME 2022 17th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/msec2022-85026.
Full textAbstract:
Abstract As for the first time in the advanced manufacturing research and development sector, the nano range bubbles (i.e., UFB) were injected to the coconut oil-based metal working fluid (COCO) to facilitate better cooling and lubrication condition for machining difficult to cut materials. Higher heat transfer characteristics, and better purification properties of the UFB were incorporated to the higher free fatty acid contained COCO to facilitate a favorable machining condition. Moreover, COCO ensures health and environmental friendliness and express higher potential to replace the toxic and hazardous synthetic oil based MWF (SynO) from the machining process. In this study, the cooling and lubrication performance of the UFB inserted novel COCO was clarified and benchmarked with a commercially available high performance SynO for machining Ti-6Al-4V. Eighteen percent cutting force reduction was obtained due to the hybrid effect of UFB and free fatty acid. Additionally, lower work tool interface temperature, surface roughness, and tool wear were obtained at the UFB inserted COCO compared to the SynO. Hence, the excellent tribological and rheological properties of the UFB inserted novel COCO has concluded high performance sustainable machining and provided a promising solution to conquer the challenges (i.e., low machinability index and sustainability) of machining Ti-6Al-4V.
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Scott-Emuakpor, Onome, Casey Holycross, Tommy George, Kevin Knapp, and Jeffery Bruns. "Fatigue and Strength Studies of Titanium 6Al-4V Fabricated by Direct Metal Laser Sintering." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42891.
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Vibratory bending fatigue life behavior of Titanium (Ti) 6Al-4V plate specimens has been assessed. The plates were manufactured via direct metal laser sintering (DMLS), which is a powder bed, laser deposition additive manufacturing process. Motivation for this work is based on unprecedented performance demands for sixth generation gas turbine engine technology. For example, the inclusion of a third stream flow for improving engine performance may add complexity and weight that could offset anticipated thrust and fuel efficiency gains. Therefore, complex, lightweight components with improved functionalities are desired. Novel component design concepts have been cost, schedule, and feasibility limited when using conventional manufacturing methods. Additive manufacturing, however, can extend the thresholds of component concepts. Though additive manufacturing can be a promising addition to the turbine engine community, the manufacturing process controls required to achieve consistency in material properties have not been fully identified. The work presented in this manuscript investigates variability in vibration-based bending fatigue life of DMLS Ti 6Al-4V compared to cold-rolled Ti 6Al-4V. Results show discrepancies between the fatigue life variation of DMLS and cold-rolled data. Along with the support of fusion and post-fusion process parameters, the fatigue results are also supported by tensile property characterization, fractography, and microscopy.
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Ha¨rtig, Frank, Christian Keck, Karin Kniel, Heinrich Schwenke, Klaus Wendt, and Franz Wa¨ldele. "Development of a Novel Gear Measuring Device of High Accuracy." In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/ptg-48105.
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The German national metrology institute, the Physikalisch-Technische Bundesanstalt (PTB), has developed a novel calibration method for gear artefacts. This reduces the current calibration uncertainty of gear standards, which is an essential step towards meeting the rising quality demands of the gear manufacturing industry. The measurement setup is based on a coordinate measuring machine (CMM) equipped with a high-precision rotary table. The key element of the novel gear measuring device is a tracking interferometer (TI) for reading the distance information. This information is combined with the reading of the coordinate measuring machine line scales in order to reduce the overall measurement uncertainty. If an optimized measurement strategy is applied, the measurement results are almost achieved with laser interferometer accuracy. First simulations and measurement results for an involute profile artefact are presented and discussed.