TAC (Time to Amplitude Convertor) is one of the most important time measurement instruments which has great significance in many fields of science, especially radiation physics. A TAC unit has been designed based on the START-STOP analog method and NIM (Nuclear Instrument Modules) standards. After designing the circuit, it was simulated by PSPICE software and constructed by discrete and integrated components. Accuracy of performance, linearity and time resolution of the TAC were checked in laboratory condition and a neutron-gamma discrimination experiment was carried out using this TAC. Results of these experiments and the spectrum of neutron-gamma discrimination completely agree with those from other similar TACs, and are, to some extent, better.

Among structured Peer-to-Peer systems, Chord has a general popularity due to its salient features like simplicity, high scalability, small path length with respect to network size, and flexibility on node join and departure. However, Chord doesn’t take into account the topology of underlying physical network when a new node is being added to the system, thus resulting in high routing latency and low efficiency in data lookup. In this paper, we introduce the TAC, a novel topology-aware protocol which is based on Chord. TAC introduces the local ring concept by dividing the geographical space into smaller areas. Through binding each new node to a proper local ring concerning its physical location, TAC considers the physical network topology of the overlay network to demonstrate more efficient key lookup. Simulation results show that TAC performs better in terms of more efficient routing and less bandwidth usage.

Fish stocks in the developing world are often depleted as a result of the application of excessive fishing effort on the part of the fishermen. A bioeconomic model with logistic growth, proportional harvesting and quadratic costs is proposed to study the effect of overcapacity on a marine fishery. Also incorporated into the model is an isoperimetric constraint to account for the annual total allowable catch (TAC). Pontryagin's maximum principle is employed to determine the necessary conditions for optimality of the model. Additionally, the sufficiency conditions that guarantee the existence and uniqueness of the optimality system are discussed. Furthermore, the relationship between the shadow price of fish stock, the shadow price of the total allowable catch and the marginal net revenue as it relates to the optimal fishing effort is explored. Numerical simulation with empirical data on the Ghana sardinella fishery is performed to validate the theoretical results. The findings of the study indicate that for a TAC equal to the maximum sustainable yield (MSY), the average fishing effort should not exceed $95\%$ of the MSY effort, provided that the initial stock size is exactly 55% of the carrying capacity.

Introduction: Antioxidant system is one of the most important protective mechanisms of saliva against free radicals. One of the most important antioxidant agents is vitamin C, which is effective in the treatment and prevention of oxidative stress. With regard to the effect of environmental, genetic, and nutritional factors on the balance between the production and expulsion of free radicals, the present study aimed to determine the effect of vitamin C on salivary total antioxidant capacity (TAC) in non-smokers. Materials and Methods: This randomized clinical trial was conducted on 60 healthy non-smokers referring to the Dental Clinic of Rafsanjan, Kerman, Iran, in 2017. After random division of the participants into three groups, the first and second groups were given 1000 and 500 milligrams of vitamin C effervescent tablet for 3 weeks, respectively. The third group did not receive any vitamin C supplements. The salivary TAC was measured before and after the intervention using an antioxidant kit and an ELISA reader. Data were analyzed using the paired t-test, one-way ANOVA followed by Duncan's post hoc test. Results: Duncan's multiple comparisons test indicated that the mean changes (increase) in salivary TAC of the receiving groups of 500 and 1000 milligrams of vitamin C were not significantly different (P>0. 05). However, the mean changes in salivary TAC in the control group were significantly lower than those receiving 500 and 1000 milligrams of vitamin C (P<0. 001). Conclusion: The results of this study showed that the use of vitamin C as an antioxidant agent increases the salivary TAC.

In this study, Tantalum carbide (TAC) nanoparticles was synthesized through the gas - solid reaction by chemical vapor deposition (CVD) method using carbon nanotubes as the carbon source. The structure of samples were studied by Transmission Electron Microscopy (TEM), Field Emission-Scanning Electron Microscopy (FE-SEM), X-Ray Diffraction (XRD) and Raman Spectroscopy. The thermal behavior of the nanoparticles were examined by TG-DTA thermal analysis. Studies indicated that during the reaction, TAC nanoparticles was formed with quasi-spherical morphology and grain size range of 30-40nm. Also, using phase and thermal analysis, the formation mechanism of Tantalum carbide nanoparticles were discussed with regarding to the role of carbon nanotubes.

Purpose: The aim of study was to evaluate reactive oxygen species (ROS), total antioxidant capacity (TAC) and ROS-TAC score as indicator for oxidative stress status as well as 8-hydrodeoxyguanosine (8-OHdG) levels as a marker for DNA damage in the seminal plasma of asthenozoospermia patients compared to normozoospermia samples. Materials and Methods: The semen samples of 28 fertile normozoospermic donors and 25 infertile men with asthenozoospermia were analyzed according to World Health Organization (WHO) criteria. ROS production was measured in neat semen samples by the chemiluminescent assay. Plasma levels of TAC was measured by commercially available colorimetric assays. The levels of DNA oxidative damage were measured by seminal plasma levels of 8-OHdG using ELISA method. ROS-TAC score was measured using principal component analysis. Results: Asthenozoospermic men had a higher ROS levels compared to the normozoospermic men (P =. 01). However, no significant difference was observed in TAC levels between the groups. ROS-TAC score in asthenozoospermic men was lower than normozoospermic men (P =. 02). The levels of 8-OHdG in the asthenozoospermic men were higher than normozoospermic men (P =. 01). Conclusion: The present study demonstrated a decrease in ROS-TAC score and, a high DNA damage in asthenozoospermia compared to normozoospermia. ROS-TAC score can predict the oxidative damage of semen samples of astenozoospermic infertile males.