Theoretical assessment of the electro-optical features of the group III nitrides (B12N12, Al12N12 and Ga12N12) and group IV carbides (C24, Si12C12 and Ge12C12) nanoclusters encapsulated with alkali metals (Li, Na and K)

2016 ◽  
Vol 363 ◽  
pp. 197-208 ◽  
Author(s):  
Elham Tahmasebi ◽  
Ehsan Shakerzadeh ◽  
Zeinab Biglari
Keyword(s):  
Alkali Metals ◽  
Group Iii Nitrides ◽  
Group Iv ◽  
Group Iii ◽  
Theoretical Assessment

Group-IV and group-V substitutional impurities in cubic group-III nitrides

2003 ◽  
Vol 68 (8) ◽  
Author(s):  
L. E. Ramos ◽  
J. Furthmüller ◽  
J. R. Leite ◽  
L. M. R. Scolfaro ◽  
F. Bechstedt
Keyword(s):  
Group Iii Nitrides ◽  
Group Iv ◽  
Group V ◽  
Group Iii ◽  
Substitutional Impurities

BULK MODULUS CALCULATIONS FOR GROUP-IV CARBIDES AND GROUP-III NITRIDES

2004 ◽  
Vol 18 (24) ◽  
pp. 1247-1254 ◽  
Author(s):  
A. MAHMOOD ◽  
L. E. SANSORES ◽  
J. HEIRAS
Keyword(s):  
Bulk Modulus ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Wide Band ◽  
Group Iii Nitrides ◽  
Group Iv ◽  
Hard Coatings ◽  
Generalized Gradient ◽  
Group Iii ◽  
Quantum Mechanical Method

Wide band gap semiconductors such as group-IV carbides ( SiC , GeC ) and group-III nitrides ( AlN , GaN and BN ) are known to be important materials for novel semiconductor applications. They also have interesting mechanical properties such as having a particularly high value for their bulk modulus and are therefore potential candidates for hard coatings. In this paper we report the theoretical calculations for the bulk modulus for zincblende and wurzite polytypes of these materials. The Density Functional and Total-energy Pseudopotential Techniques in the Generalized Gradient approximation, an ab initio quantum mechanical method, is used to obtain the theoretical structure, from which equilibrium lattice parameters and volume of the cell versus pressure may be extracted. The Murnaghan's equation of state is then used to calculate bulk modulus under elastic deformation, which is related to the hardness of a material under certain conditions. The results for bulk modulus are compared with other theoretical and experimental values reported in the literature.

Comparative studies on total energetics of nonequivalent hexagonal polytypes for group IV semiconductors and group III nitrides

2012 ◽  
Vol 28 (1) ◽  
pp. 7-16
Author(s):  
Koji Moriguchi ◽  
Kazuhito Kamei ◽  
Kazuhiko Kusunoki ◽  
Nobuyoshi Yashiro ◽  
Nobuhiro Okada
Keyword(s):  
Comparative Studies ◽  
Group Iii Nitrides ◽  
Group Iv ◽  
Group Iii ◽  
Group Iv Semiconductors ◽  
Image Position

Abstract

Analysis of surface conditioning methods on core-veneer bond strength of CAD/CAM zirconia restorations

2020 ◽  
pp. 1-11
Author(s):  
Anip K. Roy ◽  
Govind N. Prasad ◽  
Tushar V. Bhagat ◽  
Saurabh Chaturvedi ◽  
Vishwanath Gurumurthy ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Bond Strength ◽  
Shear Bond Strength ◽  
Group Iv ◽  
Control Group ◽  
Group Iii ◽  
Surface Conditioning ◽  
Group I ◽  
Alumina Particles ◽  
Scanning Electron

BACKGROUND: The increased strength of zirconia has resulted in its widespread application in clinical dentistry. Nevertheless, the fracture of veneering porcelains remains one of the key reasons of failure. OBJECTIVE: The objective of this study was to compare and analyze the influence of surface conditioning methods on the core-veneer bond strength of zirconia restorations. METHODS: Thirty specimens of zirconia core with sizes 10 × 5 × 5 mm were layered with porcelain of sizes 5 × 3 × 3 mm. On the basis of different surface conditioning methods, four groups were made: Group I: abrasion with airborne alumina particles of 110 μm size, Group II: sandblasting with silica coated alumina particles of 50 μm in size, Group III (modified group): alteration with a coating of zirconia powder prior to sintering, and Group IV (control group): metal core specimens. The shear force of all specimens was tested using a universal testing machine with a 0.5 mm/min crosshead speed. One-way analysis of variance (ANOVA) and Tukey’s post hoc pair wise comparison (p= 0.05) were performed to analyze the shear bond strength. A scanning electron microscope was used to assess the fractured specimens. RESULTS: A statistically significant difference was noted between the groups. The mean value of shear bond strength was 40.25 MPa for Group I, 41.93 MPa for Group II, 48.08 MPa for Group III and 47.01 MPa for Group IV. CONCLUSIONS: The modified zirconia group and control group demonstrated a significantly higher mean bond strength than that of Group I, where airborne particle abrasion was used. The scanning electron microscope showed that cohesive fracture in the porcelain veneers was the main problem of failure in altered zirconia. The modified zirconia specimens in Group III demonstrated significantly improved values of shear bond strength.

Plasma characteristics and the growth of group III-nitrides by metalorganic molecular beam epitaxy

1997 ◽  
Vol 26 (11) ◽  
pp. 1266-1269 ◽  
Author(s):  
J. D. Mackenzie ◽  
L. Abbaschian ◽  
C. R. Abernathy ◽  
S. M. Donovan ◽  
S. J. Pearton ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Group Iii Nitrides ◽  
Group Iii ◽  
Metalorganic Molecular Beam Epitaxy ◽  
Plasma Characteristics

scholarly journals Effect and mechanisms of reproductive tract infection on oxidative stress parameters, sperm DNA fragmentation, and semen quality in infertile males

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Kang-Sheng Liu ◽  
Xiao-Dong Mao ◽  
Feng Pan ◽  
Rui Fang An
Keyword(s):  
Reproductive Medicine ◽  
Reproductive Tract ◽  
Group Iv ◽  
Semen Parameters ◽  
Group Iii ◽  
Reproductive Tract Infection ◽  
Group I ◽  
Sperm Dna ◽  
Group Ii ◽  
Elastase Level

AbstractRecent years have seen a rising incidence of male infertility, mostly caused by the decline of sperm quality. The ratio of infertile males to infertile females has escalated from 3:7 in 2013 to current 5:5, which turns male infertility into the research focus of reproductive medicine. This study aimed to clarify the effect of reproductive tract infection by ureaplasma urealyticum (UU) and chlamydia trachomatis (CT) on the DNA integrity and routine semen parameters of infertile males. A retrospective study was performed. A total of 259 infertile males who were treated at the Andrological Laboratory Examination and Reproductive Medicine Center in our hospital were analyzed. qRT-PCR was used to examine the infection status of CT and UU. According to the eligibility criteria, we evaluated the semen parameters and biochemical data of 253 men. Based on the results of PCR, the subjects were divided into four groups: Group I (CT positive, 63 cases), Group II (UU positive, 60 cases), Group III (CT positive and UU positive, 62 cases), and Group IV (no infection, 68 cases). DNA fragmentation index (DFI), sperm count, vitality and morphology, elastase level, seminal plasma malondialdehyde (MDA), and total antioxidant capacity (TAC) were assessed. Compared to Group IV, three groups (Group I, Group II and Group III) showed difference in semen volume, proportion of sperm with normal morphology, sperm motility, progressive motility, and vitality (P < 0.05). Compared to Group IV, Group II and Group III showed difference in DFI (P < 0.05). Compared to Group IV, Group II and Group III showed difference in elastase level (P < 0.05). VCL, VSL, VAP, WOB, ROS, TM, HDS showed differences between groups of abnormal/normal WBC (*P < 0.01).UU infection significantly increased the level of seminal leukocytes only in Group II, but not in the other three groups, indicating that UU is a factor to increase the level of seminal leukocytes. Compared with the normal leukocyte group, there were significant differences in total motility, forward motility and normal sperm ratio between the two groups. The proportion of sperm with abnormal morphology (mostly in the head) showed obvious difference between groups of high and normal seminal leukocytic levels. At the same time, in this study, SCGE and SCD verified that leukocytes could damage sperm DNA by increasing ROS, which ultimately affects male fertility.

A Study on the Effect of Samoa Extract (Cleome droserifolia) on Sperm Quality in Male Albino Rats Exposed to Pyrethroid

2021 ◽  
pp. 39-45
Author(s):  
Nura I. Al-Zail ◽  
Salah F. Kamies
Keyword(s):  
Sperm Quality ◽  
Group Iv ◽  
Male Rats ◽  
Control Group ◽  
Albino Rats ◽  
Protective Agent ◽  
Group V ◽  
Group Iii ◽  
Group I ◽  
Induced Changes

Pyrethroid cyhalothrin (PC) is an insecticide that is used worldwide for pest control in agriculture and household use. Samoa extract (SE) is a potent antioxidant protecting cells from oxidative stress. The present study investigates the protective and therapeutic effect of SE on PC-induced changes in sperm quality in male rats. Fifty adult male albino rats were divided into five groups: group I: served as control; group II: received PC i.p. only (6.2 mg/kg b.wt.); group III: received SE only (100 mg/kg b.wt., p.o.) for eight weeks; group IV: received SE as a protective agent daily for eight weeks, then followed by the administration of PC (i.p.) three times a week for two weeks; group V: exposed to PC (i.p.) three times a week for two weeks, then treated with the SE daily for 8 weeks. Results showed that PC caused markedly impaired sperm quality (a count, viability, motility, and abnormality). Compared to PC-treated animals, SE in the protective group markedly restored the alteration of sperm indices. However, SE in the curative group was found to be less effective in restoring PC-induced alterations. In conclusion, the data of this study revealed that the SE as a protective agent is more effective than as a therapeutic agent. Keywords: Samoa; Pyrethroid; Sperm quality; Rat

Mechanical sensitivity of group III and IV afferents from posterior articular nerve in normal and inflamed cat knee

1986 ◽  
Vol 55 (4) ◽  
pp. 635-643 ◽  
Author(s):  
P. Grigg ◽  
H. G. Schaible ◽  
R. F. Schmidt
Keyword(s):  
Sciatic Nerve ◽  
Knee Joint ◽  
Conduction Velocity ◽  
Mechanical Stimulation ◽  
Dorsal Root ◽  
Receptive Fields ◽  
Group Iv ◽  
Mechanical Sensitivity ◽  
Group Iii ◽  
Stimulation Of

Recordings were performed from sciatic nerve or dorsal root filaments in 28 cats to study single group III (conduction velocity 2.5-20 m/s) and group IV (conduction velocity less than 2.5 m/s) units supplying the knee joint via the posterior articular nerve (PAN). In seven of these cats the knee joint had been inflamed artificially. Recordings from sciatic nerve filaments revealed responses to local mechanical stimulation of the joint in only 3 of 41 group IV units and in 12 of 18 group III units from the normal joint. In the inflamed joint 14 of 36 group IV units and 24 of 36 group III units were excited with local mechanical stimulation. In recordings from dorsal root filaments (normal joint) 4 of 11 group IV units and 7 of 13 group III units were activated by stimulating the joint locally. In the normal joint four group IV units (recorded from dorsal root filaments) responded only to rotations against the resistance of the tissue, whereas the majority of the fibers did not respond even to forceful movements. Group III units with local mechanosensitivity in the normal joint reacted strongly or weakly to movements in the working range of the joint or only to movements against resistance of the tissue. In the inflamed joint, group IV fibers (recorded in sciatic nerve filaments) with detectable receptive fields responded strongly to gentle movements or only to movements against resistance of tissue. Some did not react to movements. Group III units reacted strongly or weakly to gentle movements or only to movements against resistance of the tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

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