Evaluating the interaction of 308-nm xenon chloride excimer laser with human dentin and enamel hard tissues

Background: The pulsed output of the 308 nm XeCl laser and its photoablation action rather than photothermal action offers the ability to remove dental hard tissues with minimal generation of heat in the tissue. Materials and Methods: A total of 20 human molar teeth (ten teeth used as enamel samples and ten teeth used as dentin samples after removing the enamel tissue from their crowns) were irradiated by the laser. The crown of each sample was regarded as a cube which its lateral sides were exposed in 2Hz frequency without water cooling. Also, 18 holes for all enamel samples and 18 holes for all dentin samples were obtained. Three different amounts of energy were selected as a variable factor with 6 different numbers of pulses in each energy. The images of these holes were prepared by optic and computer combining, and the amounts of the ablation depth and effective ablation area were calculated using the MATLAB software. Results: The amounts of ablation depth were increased with increasing the number of pulses for both enamel and dentin tissues. The amounts of ablation depth were also increased with increasing the amounts of energy for both enamel and dentin tissues. The greater amounts of ablation depth and effective ablation area were observed in the dentin tissue rather than the enamel tissue. The borders of created holes were reported sharp and clear. Conclusion: The application of the XeCl laser for hard tissue removal and cavity preparation can be possible after some certain modifications

GAIN ENHANCEMENT OF DIELECTRIC RESONATOR LOADED WAVE-GUIDE ANTENNAS WITH DIELECTRIC OVERLAYS

The gain characteristics of a dielectric resonator loaded coaxial probe fed circular waveguide antenna (DRLWA) with overlaying parasitic discs have been investigated experimentally. Results indicate that, when properly spaced, the overlays can enhance the gain by more than 6 dB. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down

A Compact Analytical Design of Dual-Loop 18 GHz Frequency Synthesizer to Enhance Signal Reliability in Digital Millimeter Radio Link System

In this paper a high resolution dual-loop 17.7�19.7 GHz frequency synthesizer is presented which is compatible with ITU-R (F.595-6) standards. The investigations of phase noise and spur frequency contents are discussed in detail. The simulated and measured phase noise and spur frequency contents are similar to one another. Phase noise of �81 dBc/Hz in 17.7 GHz at 10 KHz offset frequency is measured by (HP8560) series Spectrum analyzer and it matches with predicted measurements. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down

Multifrequency Wilkinson power divider using microstrip nonuniform transmission lines

A new idea is proposed to modify the conventional Wilkinson power dividers to operate at two or several desired frequencies. The proposed structure contains two Microstrip Nonuniform Transmission Lines (MNTLs) instead of two uniform ones with nearly the same length at the minimum frequency. The strip width of MNTLs is considered variable and is written as a truncated Fourier series. Three nonuniform power dividers are designed and one of them operating at frequencies 1.0, 2.8, and 4.5 GHz is fabricated and measured. The measured results of the fabricated diplexer have a good agreement with the theoretical results. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down

Fabricate An 8.35-GHz Frequency Synthesizer

The article presents information on designing a low-noise frequency synthesizer for achieving low-phase-noise outputs past 8 GHz for digital microwave radios (DMRs). These synthesizers can be used with the DMRs, depending on advanced digital modulation such as quadrature-amplitude-modulation (QAM) and quadrature-phase-shift-keying (QPSK) formats. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down

L-carnitine reduces the adverse effects of ROS and up-regulates the expression of implantation related genes in in vitro developed mouse embryos

In vitro developed embryos are inevitably exposed to various reactive oxygen species (ROS) which may decrease the embryo's competence in assisted reproductive technology (ART) procedures. Optimization of embryo culture media using antioxidant agents could help to improve embryo quality and could overcome failures in current ART. The aim of this study was to evaluate the effects of L-carnitine (LC), an enhancer of mitochondrial activity and free radical scavenger, in culture media on early embryo competence and expression of ErbB1 and ErbB4 implantation related genes. Two-cell mouse embryos were cultured in the following four conditions: 1. LC group in media containing LC; 2.H 2O2 group exposed to H2O2 for 30 min and then transferred into a simple media; 3.H2O2+LC group exposed to H2O2 for 30 min and then transferred into a simple media containing LC; 4.the control group kept throughout in simple media. All groups were allowed to develop until the blastocyst stage. ErbB1 and ErbB4 expression were evaluated by Real-time PCR and immunocytochemistry. The expression of Sirt3 gene was also evaluated. Intracellular ROS levels were examined by DCFH-DA fluorescence intensity. In order to assess the morphological quality of the embryos, ICM and OCM number blastocyst cells were evaluated by using Hoechst and propidium iodide (PI) staining. ErbB1, ErbB4, ROS levels and cell number were compared across all in vitro groups. Our data reveal that LC significantly increases ErbB1 and ErbB4 gene and protein expression with intracellular ROS levels and Sirt3 gene expression significantly decreased after LC treatment. It is worth noting that an elevated cell number was observed in the LC-treated group compared with the other groups suggesting increased viability and/or proliferation. Our findings suggest that the use of LC could be helpful to improve preimplantation embryo culture media through its effects in decreasing ROS levels and the increase of implantation-related genes. © 2020 Elsevier Inc

The combination of retinoic acid and estrogen can increase germ cells genes expression in mouse embryonic stem cells derived primordial germ cells

A B S T R A C T Generation of germ cells from embryonic stem cells in vitro could have great application for treating infertility. The temporal expression profile of several genes was expressed at different stages of germ cell development and examined in differentiation the mouse embryonic stem cells. Cells were treated in three groups of control, with 10−8M of all-trans retinoic acid and the combination of 10−9M of 17β-Estradiol and retinoic acid for 7, 12, 17 or 22 days. Quantitative RT-PCR and Immunofluorescent were used to investigate the possible inductive effects of estrogen on mouse embryonic stem cell-derived primordial germ cells. mRNA expression of Oct4 and Dazl were downregulated in embryonic stem cells by the retinoic acid group, whereas Mvh transcription was reduced by retinoic acid and estrogen group in these cells compared to the control group. But, retinoic acid with estrogen group-treated cells exhibited increased mRNA expression of Stra8, Fragilis, Sycp3, GDF9, and Stella compared to untreated controls. The expression of Stella and Mvh proteins were remarkably increased in cell colonies. This study shows that estrogen affects the expression of specific markers of primordial germ cells. Also, estrogen and retinoic acid speed up and increase the level of expression of specific markers. Keywords: Gene expression profiling Immunofluorescent Mouse embryonic stem cells Primordial germ cells RT PC

Drug-related mutational patterns in hepatitis B virus (HBV) reverse transcriptase proteins from Iranian treatment-Naïve chronic HBV patients

Background: Immunomodulators and Nucleotide analogues have been used globally for the dealing of chronic hepatitis B virus (HBV) infection. However, the development of drug resistance is a major limitation to their long-term effectiveness. Objectives: The aim of this study was to characterize the hepatitis B virus reverse transcriptase (RT) protein variations among Iranian chronic HBV carriers who did not receive any antiviral treatments. Materials and Methods: Hepatitis B virus partial RT genes from 325 chronic in active carrier patients were amplified and directly sequenced. Nucleotide/amino acid substitutions were identified compared to the sequences obtained from the database. Results: All strains belonging to genotype D.365 amino-acid substitutions were found. Mutations related to lamivudine, adefovir, telbivudine, and entecavir occurred in (YMDD) 4% (n = 13), (SVQ) 17.23% (n = 56), (M204I/V + L180M) 2.45% (n = 8) and (M204I) 2.76% (n = 9) of patients, respectively. Conclusions: RT mutants do occur naturally and could be found in HBV carriers who have never received antiviral therapy. However, mutations related to drug resistance in Iranian treatment-naïve chronic HBV patients were found to be higher than other studies published formerly. Chronic HBV patients should be monitored closely prior the commencement of therapy to achieve the best regimen option. © 2013, KOWSAR Corp

Cochlear synaptopathy following noise exposure in Guinea pigs: Its electrophysiological and histological assessments

Exposure to high level of noise, may cause the permanent cochlear synaptic degeneration. In present study, a model of noise induced cochlear synaptopathy was established and the electrophysiological and histological metrics for its assessment was designed. 6 Guinea pigs were subjected to a synaptopathic noise (octave band of 4 kHz at 104 dB SPL, for 2-h). The amplitude growth curve of Auditory Brainstem Response (ABR) wave-I and wave-III latency shift in presence of noise were calculated. These indexes were considered in pre-exposure, 1 day post exposure (1DPE), 1 week post exposure (1WPE) and 1 month post exposure (1MPE) to noise. Finally, the samples were histologically analyzed. ABR wave-I amplitude was different between pre and 1DPE (p-value � 0.05). However, at 1WPE, it was recovered at low intensities but at 70 dB SPL and above, the differences persisted even till 1MPE. In masked ABR, the latency shift of wave-III was different between pre and 3 post exposure assessments (p-value � 0.05). Electro-microscopic analysis confirmed the synaptic degeneration, as the ribbons were larger than normal, hollow inside, and spherical and irregular in shape, also, the post synaptic density was abnormally thick and missed its flat orientation. These data revealed that noise at level below that can produce permanent hearing loss, can incur synaptic injury. So, noise is considered to be more damaging than previously thought. Accordingly, designing tools for clinical assessment of synaptopathy is beneficial in comprehensive auditory evaluation of those with history of noise exposure and also in hearing protection planning. © 2020 Tech Science Press. All rights reserved