Bulk and homoepitaxial films of III-V nitride semiconductors: Optical studies

Jaime A. Freitas, Jr 한양대학교 세라믹연구소 2005 Journal of Ceramic Processing Research Vol.6 No.3

It is well accepted that point and extended defects play an important role on the properties of III-V nitride semiconductors. It is also essential to understand the defect formation mechanisms to obtain the necessary material control to reach the full realization of the technological potential of the wide bandgap material system. Due to the nature of the centers involved a detailed and extensive investigation must be performed in controlled samples. In this work, results obtained using a combination of defect-sensitive techniques employed to detect, identify, and verify the role of defects and impurities in the structural, optical, and electronic properties of thick freestanding GaN, bulk AlN, and homoepitaxial layers are reviewed. The sharpness and line-shapes of XRD and Raman scattering lines of AlN and GaN were employed as figures of merit to evaluate the crystalline quality and homogeneity of the bulk and epitaxial layers. Detailed luminescence studies of AlN and GaN, grown by different techniques, and homoepitaxial films show evidence of the pervasive nature of some defects.

Interrelationships among endometriosis-related pain symptoms and their effects on health-related quality of life: a sectional observational study

( Marlon De Freitas Fonseca ),( Lilian Carvalho Aragao ),( Felipe Ventura Sessa ),( Jose Anacleto Dutra De Resende Jr ),( Claudio Peixoto Crispi ) 대한산부인과학회 2018 Obstetrics & Gynecology Science Vol.61 No.5

Objective To assess the correlation between different pain symptoms and different domains of women's health-related quality of life (HRQoL). Methods Seventy-seven women with deep infiltrating endometriosis were successively enrolled between June 2011 and August 2013 while being prepared to undergo laparoscopy due to pain and/or infertility. We quantified the intensities of dysmenorrhea, deep dyspareunia, chronic pelvic pain, and dyschezia (menstrual and non-menstrual) using a 11-point visual analog scale (VAS: 0-10) and the validated full versions of the Short Form 36 (SF36) and Endometriosis Health Profile (EHP30) questionnaires to assess HRQoL. The pain symptoms were considered simultaneously in a hierarchical agglomerative clustering method (exploratory multivariate approach) and the associations among scores were tested by bivariate correlation. Results Dysmenorrhea showed the lowest similarity on to the multivariate cluster analysis and no statistically significant correlation with the other pain symptoms: deep dyspareunia (P=0.244), chronic pelvic pain (P=0.108), menstrual dyschezia (P=0.238), and non-menstrual dyschezia (P=0.380). Dysmenorrhea and chronic pelvic pain were the main symptoms correlated with all domains of the SF36 and the EHP30 (core instrument) questionnaires (P<0.05). Conclusion Dysmenorrhea and chronic pelvic pain were independent factors associated with HRQoL.

Plasmonically enhanced emission from a group-III nitride nanowire emitter

Mastro, Michael A,Freitas Jr, Jaime A,Glembocki, Orest,Eddy Jr, Charles R,Holm, R T,Henry, Rich L,Caldwell, Josh,Rendell, Ronald W,Kub, Fritz,Kim, J IOP Pub 2007 Nanotechnology Vol.18 No.26

<P>The plasmonic response from a nanotextured silver coating was utilized to enhance the transfer of ultraviolet light generated in a group-III nitride nanowire emitter. A two-step approach was developed in a metal–organic chemical vapour deposition system to grow nanowires initially vertically by the vapour–liquid–solid mechanism and, subsequently, laterally by increasing the growth temperature and the group-V/III reactant ratio. This controllably produced a 20 nm GaN:Si core with a 200 nm outer-diameter AlGaN:Mg sheath structure. Solvothermal chemistry based on an ethylene glycol solvent was employed to deposit a silver coating that approximated a dense packing of metallic nanospheres. Nanoscale emission and plasmonically enhanced transfer of this energy were simulated to aid the development and understanding of this system.</P>

Evolution of strain throughout gallium nitride deposited on silicon carbide

김지현,M.A. Mastro,N.D. Bassim,J.A. Freitas Jr.,M.E. Twigg,C.R. Eddy Jr.,D.K. Gaskill,R.L. Henry,R.T. Holm,P.G. Neudeck,A.J. Trunek,J.A. Powell 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.5

During GaN growth on an on-axis SiC substrate, a large density of dislocations (~109 cm−2) is unavoidably generated by the GaN/SiC misfit, uncontrolled misorientation in the substrate and defects present at the surface of the substrate. Recently a unique SiC substrate was developed with step-free and stepped mesas as well as continuous surface areas similar to a standard wafer all in close proximity. It is now possible to isolate the influence of defects and steps on the deposition of GaN on SiC. This paper provides a link between the dislocation environment and the strain state in the GaN film as well as the change of this strain with increasing thickness.

Influence of polymer-coated slow-release urea on total tract apparent digestibility, ruminal fermentation and performance of Nellore steers

Gardinal, R.,Calomeni, G.D.,Consolo, N.R.B.,Takiya, C.S.,Freitas, J.E. Jr,Gandra, J.R.,Vendramini, T.H.A.,Souza, H.N.,Renno, F.P. Asian Australasian Association of Animal Productio 2017 Animal Bioscience Vol.30 No.1

Objective: Two experiments were performed to evaluate the effects of coated slow-release urea on nutrient digestion, ruminal fermentation, nitrogen utilization, blood glucose and urea concentration (Exp 1), and average daily gain (ADG; Exp 2) of steers. Methods: Exp 1: Eight ruminally fistulated steers [$503{\pm}28.5kg$ body weight (BW)] were distributed into a d $4{\times}4$ Latin square design and assigned to treatments: control (CON), feed grade urea (U2), polymer-coated slow-release urea A (SRA2), and polymer-coated slow-release urea B (SRB2). Dietary urea sources were set at 20 g/kg DM. Exp 2: 84 steers ($350.5{\pm}26.5kg$ initial BW) were distributed to treatments: CON, FGU at 10 or 20 g/kg diet DM (U1 and U2, respectively), coated SRA2 at 10 or 20 g/kg diet DM (SRA1 and SRA2, respectively), and coated SRB at 10 or 20 g/kg diet DM (SRB1 and SRB2, respectively). Results: Exp 1: Urea treatments (U2+SRA2+SRB2) decreased (7.4%, p = 0.03) the DM intake and increased (11.4%, p<0.01) crude protein digestibility. Coated slow-release urea (SRA2+-SRB2) showed similar nutrient digestibility compwared to feed grade urea (FGU). However, steers fed SRB2 had higher (p = 0.02) DM digestibility compared to those fed SRA2. Urea sources did not affect ruminal fermentation when compared to CON. Although, coated slow-release urea showed lower (p = 0.01) concentration of $NH_3-N$ (-10.4%) and acetate to propionate ratio than U2. Coated slow-release urea showed lower (p = 0.02) urinary N and blood urea concentration compared to FGU. Exp 2: Urea sources decreased (p = 0.01) the ADG in relation to CON. Animals fed urea sources at 10 g/kg DM showed higher (12.33%, p = 0.01) ADG compared to those fed urea at 20 g/kg DM. Conclusion: Feeding urea decreased the nutrient intake without largely affected the nutrient digestibility. In addition, polymer-coated slow-release urea sources decreased ruminal ammonia concentration and increased ruminal propionate production. Urea at 20 g/kg DM, regardless of source, decreased ADG compared both to CON and diets with urea at 10 g/kg DM.

Physical exercise programs at Basic Healthcare Units decrease body fat and improve the functional capacity of women over 50 years old

Fabrício Eduardo Rossi,Anderson Rogério Lecca,Luiz Gustavo Perón Martins,Luciana Sanae Ota Takahashi,Diego Giuliano Destro Christofaro,Luís Alberto Gobbo,Ismael F. Freitas Jr 한국운동재활학회 2017 JER Vol.13 No.3

This study verified the effects of a physical exercise program performed at Basic Healthcare Units on the body composition and functional capacity of women over 50 years old and to compare these variables according to age. Forty-eight women (age, 65.4± 7.3 years) were assessed. The program lasted 20 weeks, and was conducted 2 times per week, 60 min/day. Body mass and height were collected and body mass index (BMI) was calculated. Bioelectrical impedance was used to estimate fat mass and fat free mass. Functional capacities: handgrip test, Timed Up and Go (TUG) test, and Guralnick test were assessment. Weight (68.7± 12.5 [pre]× 66.8± 12.5 [post], P< 0.001), BMI (28.5± 4.1 kg/ m2 [pre]× 27.6± 4.0 kg/m2 [post], P< 0.001), and fat mass (28.4± 7.8 kg [pre]× 26.4± 7.3 kg [post], P< 0.001) were decreased. For functional capacity, handgrip (21.2± 5.8 kg [pre]× 22.9± 6.9 kg [post], P= 0.014), lower limb strength (12.0± 3.0 sec [pre]× 8.5± 2.2 sec [post], P< 0.001), TUG (8.4 ±1.5 sec [pre] ×7.6 ±1.1 se [post], P<0.001) and Guralnik tests (10.6± 1.6 [pre]× 11.8± 0.5 [post], P< 0.001) were improved. 20 weeks of exercise program performed at Basic Healthcare Units decreased body fat and improvement of functional capacity of women over 50 years old and there was difference according to age only on the body composition variables.