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1.
J Infect Chemother ; 29(6): 586-591, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-36849098

RESUMEN

BACKGROUND: In the context of the coronavirus disease 2019 (COVID-19) pandemic, a rapid and reliable point-of-care test is an essential tool for controlling the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In particular, an immunochromatography test (ICT) that uses saliva specimens for rapid antigen detection not only reduces the risk of secondary infections but also reduces the burden on medical personnel. METHODS: The newly developed salivary antigen test kit "Inspecter Kowa® SARS-CoV-2" is an ICT to which saliva specimens can be directly applied. We evaluated its usefulness in comparison with reverse transcription quantitative PCR (RT-qPCR) and the Espline® SARS-CoV-2 Kit for the detection of SARS-CoV-2 using nasopharyngeal swab specimens. In this study, 140 patients with suspected symptomatic COVID-19 who visited our hospital were enrolled, and nasopharyngeal swab and saliva specimens were collected after they consented to participate in the study. RESULTS: Inspector Kowa SARS-CoV-2 was positive in 45 of 61 (73.8%) saliva that were positive by RT-qPCR and the Espline® SARS-CoV-2 Kit was also positive in 56 of 60 (93.3%) Np swabs that were positive by RT-qPCR. Good antigen detection was achieved by ICT with saliva and nasopharyngeal swab specimens when viral load was ≥105 copies/mL, whereas detection sensitivity was low when viral load was <105 copies/mL, especially in saliva specimens. CONCLUSION: This ICT for the detection of SARS-CoV-2 salivary antigen is an attractive tool that does not require specialized equipment and allows patients to perform the entire process from sample collection to self-diagnose and to reduce the burden on medical care during a pandemic.


Asunto(s)
COVID-19 , SARS-CoV-2 , Humanos , COVID-19/diagnóstico , Prueba de COVID-19 , Saliva , Técnicas de Laboratorio Clínico/métodos , Manejo de Especímenes/métodos , Nasofaringe
2.
Anal Biochem ; 604: 113792, 2020 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-32622977

RESUMEN

We analyzed seminal plasma of 88 normozoospermic, 40 oligozoospermic and 32 azoospermic donors. During this study, we focus to record the protamine concentration in the seminal plasma of azoospermic donors. The seminal protamine concentrations were found to be 19.6-62.8 IU/ml in normozoospermic donors; 25.4-100.8 IU/ml in oligozoospermic donors; and, most notably, 23.7-219.4 IU/ml in azoospermic donors. These results indicate that, based on seminal plasma protamine concentrations, even azoospermic donors were able to produce as much sperm as normo- and/or oligozoospermic donors. Using statistical analyses, significant differences were found between azoospermic and normozoospermic donors (p = 0.0018). Protamine content was found to be a direct marker for the presence of sperm. The data from this study provided evidence for a new therapeutic approach for testicular varicose veins, which are found in obstructive or non-obstructive azoospermia. High seminal protamine concentrations indicated the future possibility of acquiring childbearing sperm for insemination sperm injection (ICSI) and testicular sperm extraction (TESE), even with azoospermic donors. Given these results, we also suggest a new cut-off value for acquisition of childbearing sperm in selection for ICSI.


Asunto(s)
Azoospermia/diagnóstico , Protaminas/análisis , Semen/química , Espermatozoides/química , Humanos , Masculino , Inyecciones de Esperma Intracitoplasmáticas
3.
Appl Opt ; 58(26): 7145-7150, 2019 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-31503987

RESUMEN

A scheme is presented for an optical vortex (OV) generator comprising a uniaxially aligned azo-dye-doped liquid crystal (ADDLC) and a space-variant polarization projection (SVPP) system. The SVPP system consisting of an electro-optic modulator and a micro-electromechanical system projects a time-averaged SVP field equal to a vector beam onto the ADDLC and fabricates a three-dimensional twisted anisotropic structure, which has spatial phase modulation properties from plane to helical shape. The generation of OVs with odd- and even-numbered topological charge is experimentally demonstrated. As a flexible and broadband spatial light modulator, the proposed scheme should be applicable to the research and development of OV applications.

4.
J Assist Reprod Genet ; 32(6): 917-23, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25877372

RESUMEN

PURPOSE: We aimed to investigate the effects of FSH for promoting spermatogenesis in mice with low-dose doxorubicin-induced spermatogenesis impairment. METHODS: Eight-wk-old male imprinting control region mice were divided into three groups. Groups D and F received 0.5 mg/kg of doxorubicin twice weekly for 5 weeks. Group C received saline instead of doxorubicin. After inducing spermatogenesis impairment, group D was treated daily with saline for 4 weeks. Group F was given 1 IU of recombinant human FSH daily for 4 weeks. Spermatogenesis recovery was evaluated based on the testis weight, sperm count, histological assessment, and mating. The percentage of sperm with unfragmented deoxyribonucleic acid (DNA) was analyzed by single-cell pulsed-field gel electrophoresis, and the serum FSH levels were measured. RESULTS: The elevation of serum FSH advanced slowly. The testis weight, sperm count, percentage of seminiferous tubules with spermatogenesis, percentage of sperm with unfragmented DNA and pregnancy rate were significantly increased by the administration of FSH. CONCLUSION: Our study findings indicated that the immediate administration of exogenous FSH can promote the recovery from impaired spermatogenesis induced by low-dose doxorubicin before endogenous FSH increases to the maximum level.


Asunto(s)
Hormona Folículo Estimulante/farmacología , Espermatogénesis/efectos de los fármacos , Animales , Antibióticos Antineoplásicos/toxicidad , Doxorrubicina/toxicidad , Fertilidad , Hormona Folículo Estimulante/sangre , Infertilidad Masculina/inducido químicamente , Infertilidad Masculina/tratamiento farmacológico , Masculino , Ratones , Ratones Endogámicos ICR , Tamaño de los Órganos , Espermatozoides/efectos de los fármacos , Espermatozoides/fisiología , Testículo/efectos de los fármacos , Testosterona/sangre
5.
Sci Rep ; 14(1): 840, 2024 01 08.
Artículo en Inglés | MEDLINE | ID: mdl-38191596

RESUMEN

We here developed a novel angle-modulated two-dimensional single cell pulsed-field gel electrophoresis (2D-SCPFGE). Variations in current-application-time and rotation angle generated different alignments of DNA fibers and segments. After the first run, the specimen was turned by 150° (2D-SCPFGE-0-150) to detect naturally occurring the earliest stage of DNA fragmentation or 75° (2D-SCPFGE-0-75) to analyze artificially induced cleavage. The former revealed that a part of long chain fibers remained at the origin and long segments were still tangled in the bundle of elongated fibers after the first run. The latter visualized the dose-dependent cleavage of DNA by EcoR1. Multicycle 2D-SCPFGE was useful for generating 2D-alignments of single nuclear DNA fibers, which is the first step for visualization of single-strand breaks on stretched fibers. To date, many articles have accepted the pathogenetic significances of DNA fragmentation in human sperm for male infertility and congenital anomaly. It is necessary to perform multivariate analyses of not only earliest-stage DNA fragmentation but also other types of damage, including single-strand breaks, in sequential DNA fibers. 2D-SCPFGE is the fundamental tool for understanding single nuclear DNA damages.


Asunto(s)
Semen , Espermatozoides , Humanos , Masculino , Fragmentación del ADN , Electroforesis en Gel de Campo Pulsado , ADN
6.
Sci Rep ; 14(1): 10891, 2024 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-38740769

RESUMEN

Direct growth of oxide film on silicon is usually prevented by extensive diffusion or chemical reaction between silicon (Si) and oxide materials. Thermodynamic stability of binary oxides is comprehensively investigated on Si substrates and shows possibility of chemical reaction of oxide materials on Si surface. However, the thermodynamic stability does not include any crystallographic factors, which is required for epitaxial growth. Adsorption energy evaluated by total energy estimated with the density functional theory predicted the orientation of epitaxial film growth on Si surface. For lower computing cost, the adsorption energy was estimated without any structural optimization (simple total of energy method). Although the adsorption energies were different on simple ToE method, the crystal orientation of epitaxial growth showed the same direction with/without the structural optimization. The results were agreed with previous simulations including structural optimization. Magnesium oxide (MgO), as example of epitaxial film, was experimentally deposited on Si substrates and compared with the results from the adsorption evaluation. X-ray diffraction showed cubic on cubic growth [MgO(100)//Si(100) and MgO(001)//Si(001)] which agreed with the results of the adsorption energy.

7.
Biomed Chromatogr ; 27(4): 535-8, 2013 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-23018892

RESUMEN

Monomethylarginine, asymmetric dimethylarginine and symmetric dimethylarginine were separated on a Wakopak Combi ODS with an acetonitrile-100 mm potassium phosphate buffer (pH 7.0; 1:1, v/v). Dimethylarginines were derived from o-phthalaldehyde for the fluorescence detector and from 6-ferrocenyl-1-hexanethiol for the electrochemical detector. The detection limits of the dimethylarginines in spiked plasma were 0.3-0.5 pmol by electrochemical detection and 1-2 pmol by fluorescence detection. The detection limits were improved over 30 times by electrochemical detection and 10 times by fluorescence detection compared with previous reports. In previous derivatization liquid chromatography, the reaction solutions, o-phthalaldehyde, 2-mercaptethanol and dimethylarginines were unstable and required quick derivatization at 4°C. By our proposed pre-column methods, the dimethylarginines were derivatized at room temperature and the fluorescent products were stable for 6 h. The manipulation performance was greatly advanced compared with previous LC reports. This is the first report on stable and sensitive dimethylarginines by dual detection. The selectivity was also improved by dual detection. The proposed method was applied to preliminary monitoring of dimethylargines in plasma and urine.


Asunto(s)
Arginina/análogos & derivados , Cromatografía Líquida de Alta Presión/métodos , Compuestos Ferrosos/química , Compuestos de Sulfhidrilo/química , o-Ftalaldehído/química , Arginina/sangre , Arginina/aislamiento & purificación , Arginina/orina , Cromatografía Líquida de Alta Presión/instrumentación , Técnicas Electroquímicas , Fluorescencia , Humanos , Límite de Detección , Metalocenos
8.
CEN Case Rep ; 12(4): 390-396, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-36864233

RESUMEN

During the treatment of a patient on hemodialysis with severe coronavirus disease 2019 (COVID-19), the patient was weaned from extracorporeal membrane oxygenation, which was used to treat severe COVID-19 pneumonia. However, the patient's condition worsened after the peak infection phase of COVID-19 because of acute respiratory distress syndrome with suspected hemophagocytic lymphohistiocytosis (HLH). After a bone marrow biopsy confirmed the diagnosis, methylprednisolone pulse therapy, followed by combination therapy (including oral prednisolone and cyclosporine) was immediately administered, and the patient survived. Because HLH can occur a month or more after the onset of COVID-19, even if the viral load is reduced to the point of being undetectable by reverse transcriptase-polymerase chain reaction, it can be considered to correspond to the "post-acute COVID-19 syndrome," which has recently been proposed. Early intervention is necessary, because HLH can be fatal. Therefore, it is important to know that HLH can occur at any stage of COVID-19 and to pay attention to the patient's progress over time, including checking the HScore.


Asunto(s)
COVID-19 , Linfohistiocitosis Hemofagocítica , Humanos , COVID-19/complicaciones , Linfohistiocitosis Hemofagocítica/complicaciones , Linfohistiocitosis Hemofagocítica/diagnóstico , Linfohistiocitosis Hemofagocítica/terapia , Médula Ósea/patología , Bazo
9.
Orthop J Sports Med ; 11(9): 23259671231195030, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37693806

RESUMEN

Background: Return-to-sports (RTS) rates after anterior cruciate ligament (ACL) reconstruction (ACLR) differ according to the level at which patients return. It is unclear whether the level of RTS is affected by psychological readiness to return. Purpose: To examine the association between psychological readiness to RTS and subjective RTS level 12 months after ACLR. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 47 patients who underwent unilateral primary ACLR surgery were enrolled. Assessments at 6 and 12 months postoperatively consisted of knee strength testing (isokinetic quadriceps and hamstring strength), the International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC-SKF), and the Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scale to measure psychological readiness to RTS. Patients were assigned to 1 of 3 subgroups based on their subjective assessment of RTS level at 12 months postoperatively: RTS at or above preinjury level (RTS≥Pre; n = 19), RTS below preinjury level (RTS

10.
Intern Med ; 2023 Nov 13.
Artículo en Inglés | MEDLINE | ID: mdl-37952957

RESUMEN

We herein report a case of diffuse large B-cell lymphoma (DLBCL) involving multiple renal and bone infiltrations presenting with giant cell arteritis-like (GCA)-like manifestations. One month prior, the present patient had left-sided temporal headache, jaw claudication, and renal failure. The patient was diagnosed with DLBCL based on a renal biopsy. After rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) plus intrathecal methotrexate/cytarabine/prednisone and rituximab, high-dose methotrexate, and cytarabine (R-MA) chemotherapy, the patient's clinical manifestations improved, and complete remission was achieved. DLBCL rarely but occasionally presents with GCA-like manifestations or multiple renal and bone infiltrations, highlighting the need for prompt and aggressive combination chemotherapy.

11.
Materials (Basel) ; 16(17)2023 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-37687470

RESUMEN

New types of hybrid aluminum joints: Al-acrylonitrile butadiene styrene (ABS) carbon fiber reinforced thermoplastic polymer (CFRTP) designated Al/Ni-CFP/ABS, and Al-18-8 Stainless steel, Al/Ni-CFP/18-8, by Ni-plated carbon fiber plug (Ni-CFP) insert not before seen in the literature have been fabricated. The goal is to take advantage of extremely high ~6 mm CF surface area for high adhesion, to enhance the safety level of aircraft and other parts. This is without fasteners, chemical treatment, or glue. First, the CFP is plated with Ni. Second, the higher melting point half-length is spot welded to the CFP; and third, the remaining half-length is fabricated. The ultimate tensile strength (UTS) of Al/Ni-CFP/ABS was raised 15 times over that of Al/ABS. Normalized cUTS according to CFP cross-section by Rule of Mixtures for cAl/Ni-CFP/18-8 was raised over that of cAl/Ni-CFP/18-8 from 140 to 360 MPa. Resistance energy to tensile deformation, UT, was raised 12 times from Al/ABS to Al/Ni-CFP/ABS, and 6 times from Al/CFP/18-8 to Al/Ni-CFP/18-8. Spot welding allows rapid melting followed by rapid solidification for amorphous metal structures minimizing grain boundaries. The Ni-coating lowers or counters the effects of brittle Al4C3 and FexC formation at the interface and prevents damage by impingement to CFs, allowing joints to take on more of the load.

12.
ACS Omega ; 8(19): 17053-17063, 2023 May 16.
Artículo en Inglés | MEDLINE | ID: mdl-37214720

RESUMEN

Submerged plasma-assisted discharge direct patterning of diamond-like carbon (DLC) onto the silicon substrate in ambient conditions has succeeded as a new and novel soft solution process. In this environmentally benign technique, a copious amount of pure ethanol (ca. 4 mL) was locally activated with a maximum of ca. 0.23 mkWh by an as-electrochemically synthesized ultrasharp tungsten tip. With the assisted submerged plasma, the decomposed ethanol molecules are anodically patterned directly onto the silicon substrate in ambient conditions. The physical nature of DLC patterns was accessed by profilometry, atomic force microscopy, scanning electron microscopy, and transmission electron microscopy analysis. Furthermore, Fourier-transform infrared, Raman, and X-ray photoelectron spectra were analyzed for chemical compositions and structures, such as surface functionalization, carbon-carbon bonding, and sp2-sp3 ratio, respectively. From a Berkovich-configured nanoindentation analysis, Young's modulus and hardness have shown increasing trend with increasing sp3-sp2 ratio in DLC patterns of 68.5 and 2.8 GPa, respectively. From the electrochemical cyclovoltammetry analysis, a maximum areal specific capacitance of 205.5 µF/cm2 has been achieved at a scan rate of 5 mV/s. The one-step, green, and environmentally sustainable approach of rapid formation of DLC patterns is thus a promising technique for various carbon-based electrode fabrication processes.

13.
J Nanosci Nanotechnol ; 12(3): 2320-5, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22755053

RESUMEN

Nano-cube MgO particles were formed on Si substrates by deposition of an MgO target using pulsed laser deposition method. An epitaxial film grows on Si(001) substrate with its contraction of lattice constants. In this study, expecting high quality MgO film, the MgO film prepared in the oxygen pressure ranging from 75-400 mTorr at the high temperature of -750 degrees C. The deposited MgO showed the growth of (001) preferred orientation on the Si(001) substrate. However, X-ray Photoelectron Spectroscopy (XPS) indicated the MgO film did not form a continuous film on the Si surface. Interestingly, the surface morphology observed by an Atomic Force Microscopy (AFM) showed nano-cube MgO particles scattered on the smooth surface of Si substrate. After annealing the nano-cube MgO, the shape of MgO particles were changed from nano-cube to round shaped particles. The AFM image of the surface showed round shaped MgO nanoparticles scattered on rough surface. X-ray Diffraction (XRD) revealed the epitaxial growth of MgO(001) with cubic on cubic arrangement on the Si(001) substrate (MgO[100] parallel to Si[100]).

14.
Materials (Basel) ; 15(9)2022 Apr 29.
Artículo en Inglés | MEDLINE | ID: mdl-35591553

RESUMEN

A literature review of up-to-date methods to strengthen Ti/carbon-fiber-reinforced polymer (CFRP) hybrid joints is given. However, there are little or no studies on Ti/CFRP joints by carbon fiber plug insert, which takes advantage of the extremely high surface adhesion area of ~6 µm CFs. Therefore, we cover the current status and review our previously published results developing hybrid joints by a CF plug insert with spot-welded Ti half-lengths to enhance the safety levels of aircraft fan blades. A thermoset Ti/CF/epoxy joint exhibited an ultimate tensile strength (UTS) of 283 MPa when calculated according to the rule of mixtures (RM) for the CF cross-section portion. With concern for the environment, thermoplastic polymers (TPs) allowed recyclability. However, a drawback is easy CF pull-out from difficult-to-adhere TPs due to insufficient contact sites. Therefore, research on a novel method of homogeneous low voltage electron beam irradiation (HLEBI) to activate a bare CF half-length prior to dipping in a TP resin was reviewed and showed that the UTS by the RM of Ti/EBCF/acrylonitrile butadiene styrene (ABS) and Ti/EBCF/polycarbonate (PC) joints increased 154% (from 55 to 140 MPa) and 829% (from 30 to 195 MPa), respectively, over the untreated sample. The optimum 0.30 MGy HLEBI prevented CF pull-out by apparently growing crystallites into the TP around the CF circumference, raising the UTS amount closer to that of epoxy.

15.
Elife ; 112022 03 22.
Artículo en Inglés | MEDLINE | ID: mdl-35315771

RESUMEN

DNA methylation, repressive histone modifications, and PIWI-interacting RNAs are essential for controlling retroelement silencing in mammalian germ lines. Dysregulation of retroelement silencing is associated with male sterility. Although retroelement silencing mechanisms have been extensively studied in mouse germ cells, little progress has been made in humans. Here, we show that the Krüppel-associated box domain zinc finger proteins are associated with DNA methylation of retroelements in human primordial germ cells. Further, we show that the hominoid-specific retroelement SINE-VNTR-Alus (SVA) is subjected to transcription-directed de novo DNA methylation during human spermatogenesis. The degree of de novo DNA methylation in SVAs varies among human individuals, which confers significant inter-individual epigenetic variation in sperm. Collectively, our results highlight potential molecular mechanisms for the regulation of retroelements in human male germ cells.


Asunto(s)
Metilación de ADN , Retroelementos , Animales , Epigenómica , Células Germinativas/metabolismo , Humanos , Masculino , Mamíferos/genética , Ratones , Retroelementos/genética , Espermatogénesis/genética
16.
Phys Ther Sport ; 58: 74-79, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36223691

RESUMEN

OBJECTIVE: To investigate the association of psychological readiness at 9 months after anterior cruciate ligament reconstruction (ACLR) with knee strength and range-of-motion (ROM) at 3 and 9 months postoperatively. DESIGN: Retrospective cohort study. SETTING: Private orthopedic hospital. PARTICIPANTS: Seventy-eight patients after ACLR. MAIN OUTCOMES MEASURES: The participants completed the anterior cruciate ligament-return to sport after injury (ACL-RSI) scale as an assessment of psychological readiness at 9 months after ACLR. Isometric and isokinetic quadriceps and hamstring strength were measured by a dynamometer at 3 and 9 months postoperatively. Knee extension and flexion ROM were measured in 5° increments with a standard goniometer at 3 and 9 months postoperatively. RESULTS: Univariate regression analysis showed that age, limb symmetry index (LSI) of quadriceps strength at 3 and 9 months, and knee extension ROM deficit (>5°) at 3 and 9 months were associated with ACL-RSI scores at 9 months (P < 0.05). Age and LSI of quadriceps strength at 3 months remained significant predictors of ACL-RSI scores at 9 months in multiple regression analysis (R2 = 0.20, P < 0.001). CONCLUSIONS: Early improvements in quadriceps strength after ACLR may have a positive impact on psychological readiness at 9 months postoperatively.


Asunto(s)
Lesiones del Ligamento Cruzado Anterior , Reconstrucción del Ligamento Cruzado Anterior , Humanos , Lactante , Lesiones del Ligamento Cruzado Anterior/cirugía , Lesiones del Ligamento Cruzado Anterior/psicología , Volver al Deporte/psicología , Estudios Retrospectivos , Reconstrucción del Ligamento Cruzado Anterior/psicología , Ligamento Cruzado Anterior/cirugía , Músculo Cuádriceps , Fuerza Muscular
17.
Materials (Basel) ; 15(21)2022 Oct 30.
Artículo en Inglés | MEDLINE | ID: mdl-36363216

RESUMEN

Strong adhesion between recyclable thermoplastic (TP) polymer and carbon fiber (CF) has always been highly sought after. Therefore, for an interlayered CF reinforced TP polypropylene (CFRTPP) composite composed of 3 sized CF plies, alternating between 4 PP sheets, designated [PP]4[CF]3, a process of activating CF plies directly on both sides with homogeneous low energy electron beam irradiation (EBI) under N2 gas, prior to lamination assembly and hot press of 4.0 MPa at 493 K for 3 min was carried out. Experimental results showed EBI dose of 43.2, 129, or 216 kGy significantly raised Charpy impact values, auc at all fracture probabilities, Pf. The 129 kGy dose appeared to be at or near optimum increasing auc 103%, 83%, and 65% at low-, median-, and high-Pf = 0.07, 0.50, and 0.93; while raising statistically lowest impact value, as at Pf = 0 calculated by 3-dimensional Weibull equation about 110%, indicating increased safety and reliability. It is assumed dangling bonds generated by the EBI rapidly form covalent bonds CF:C:O:C:PP and CF:C:C:PP at the interface, along with cross-linking in the PP near the CF. This is by charge transfer from CF to PP.

18.
Sci Rep ; 12(1): 15809, 2022 Sep 22.
Artículo en Inglés | MEDLINE | ID: mdl-36138094

RESUMEN

Growth morphology of carbon clusters deposited on different substrates were investigated by theoretical and experimental approach. For theoretical approach, molecular dynamics was employed to evaluate an adsorptive stability of different size of carbon clusters placed on different substrates. The adsorptive stability was estimated by the difference of total energy of supercell designed as carbon cluster placed on a certain crystal plane of substrate. Among the simulations of this study, carbon cluster flatly settled down on the surface of SrTiO[Formula: see text](001). The result was experimentally verified with layer by layer growth of graphene by pulsed laser deposition in carbon dioxide atmosphere. The absorptive stability can be useful reference for screening substrate for any target material other than graphene.

19.
Nanotechnology ; 22(17): 175307, 2011 Apr 29.
Artículo en Inglés | MEDLINE | ID: mdl-21411922

RESUMEN

After a laser annealing experiment on Si wafer, we found an asymmetric sheet resistance on the surface of the wafer. Periodic nano-strip grating lines (nano-SGLs) were self-organized along the trace of one-time scanning of the continuous wave (CW) laser. Depending on laser power, the nano-trench formed with a period ranging from 500 to 800 nm with a flat trough between trench structures. This simple method of combining the scanning laser with high scanning speed of 300 m min(-1) promises a large area of nanostructure fabrication with a high output. As a demonstration of the versatile method, concentric circles were drawn on silicon substrate rotated by a personal computer (PC) cooling fan. Even with such a simple system, the nano-SGL showed iridescence from the concentric circles.

20.
ACS Appl Mater Interfaces ; 13(4): 5208-5215, 2021 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-33475346

RESUMEN

In this work, we show that polarization rotation enhances the piezoresponse in a high-performance lead-free piezoelectric material, Na1/2Bi1/2V1-xTixO3, a solid solution between tetragonal Na1/2Bi1/2VO3 and rhombohedral Na1/2Bi1/2TiO3, obtained by high-pressure synthesis. The system forms a pure perovskite structure with a favorable morphotropic phase boundary (MPB) located around x = 0.90, which separates the tetragonal and rhombohedral phases. In addition, a distinct monoclinic phase with polarization rotation as functions of composition and temperature is observed. XRD measurements revealed the moderately high Curie temperature of 523 K at x = 0.95 in the MPB. The piezoelectric coefficient d33 of the monoclinic x = 0.95 sample, 42 pC/N, is higher than those of the tetragonal and rhombohedral phases. Even though the present lead-free Na1/2Bi1/2V1-xTixO3 ceramics feature smaller d33 values compared to many currently available lead-free piezoelectric materials as a result of insufficient poling and low density, we expect our findings open up opportunities for exploring promising lead-free piezoelectric materials in Na1/2Bi1/2VO3-based perovskites.

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