Effect of zinc sources on milk yield, milk composition and plasma concentration of metabolites in dairy cows

This study was conducted to evaluate the effects of different sources of zinc (Zn) on feed intake, milk yield, milk composition, and blood metabolites. Twenty-four dairy cows were randomly allocated to one of four treatments in a randomized complete block design. The treatments consisted of i) control diet (no zinc supplementation), ii) zinc oxide (ZnO), iii) zinc glycine (ZnGly), and iv) zinc nano (ZnN). The Zn sources were added to provide 60 mg of supplemental Zn per kg diet. There were no differences in dry matter intake, milk yield, bodyweight, and body condition score of the cows between treatments. Zinc supplementation in the form of ZnN and ZnGly decreased somatic cell count compared with the other treatments. The superoxide dismutase and plasma Zn concentrations in the cows provided ZnGly and ZnN were greater than those in the ZnO and control groups. No difference was detected between groups in biochemical and haematological parameters, except that blood urea nitrogen concentrations of cows supplemented with ZnGly and ZnN were less than for the ZnO supplemented and control cows. The results showed that nano and organic Zn sources in the diet of dairy cows were more suitable than inorganic Zn as supplements for dairy cows.Keywords: milk composition, milk production, metabolism, somatic cell coun

Efficacy of tenofovir disoproxil fumarate therapy in nucleoside-analogue naive Iranian patients treated for chronic hepatitis B

Background: Tenofovir disoproxil fumarate (TDF) is a new effective treatment option for patients with chronic hepatitis B (CHB). Objectives: To evaluate TDF efficacy in nucleos(t)ide analogues (NAs)-naive Iranian patients with CHB. Patients and Methods: The NA-naive patients received TDF for at least six months. The primary endpoint was the proportion of patients achieving a complete virological response (CVR) during the treatment. Multivariate Cox regression analysis determined predictive factors independently associated with the time to CVR. The secondary endpoints were biochemical and serological responses, frequency of virological breakthrough, genotypic resistance development, safety and tolerability. Results: In all, 93 patients (64.5 hepatitis B e antigen HBeAg-negative) were eligible. Of these, 70 patients completed 24 months of treatment. The cumulative CVR rates in HBeAg-negative and HBeAg-positive patients were 87% versus 53% at 24 months, respectively. The multivariate Cox regression model showed only HBeAg positivity at baseline and a high baseline HBV DNA level were independent factors predicting a CVR. No patient achieved hepatitis B surface antigen (HBsAg) and HBeAg loss or seroconversion and no virologic breakthrough occurred. A new amino acid substitution (rtD263E) was observed to develop in 60% of patients with viremia. Conclusions: The cumulative CVR rates showed that patients with HBeAg-negative have better virologic respond than those with HBeAg-positive during the same period. The rtD263E mutation might be associated with partial resistance to TDF. © 2015, Kowsar Corp

State Space Modeling of an Offshore Wind Power Plant With an MMC-HVDC Connection for an Eigenvalue-Based Stability Analysis

Large offshore wind power plants (OWPPs) installed far from the coastline are emerging to benefit from the strong and steady wind resources available at these locations. The high-voltage direct-current (HVDC) transmission system based on the modular multilevel converter (MMC) is the most appropriate solution to transmit the produced energy to the onshore grid, in a way that a complex power-electronic-based electrical system is formed at the OWPP. Undesired interactions can occur between the MMC-based HVDC station, the several wind-turbine (WT) converters, and the passive elements of the offshore grid. To guarantee a safe and reliable operation of the OWPP, a small-signal analysis must be performed in advance to predict possible unstable situations and their root causes, in a way as to take corrective measures to avoid them. In this paper, a state-space model of an OWPP is developed adopting a recently proposed model in multiple dq frames of the MMC, which considers the internal dynamics of the converter. With the developed model, an eigenvalue-based stability assessment is carried out, where participation factors are calculated to identify the main contributors to the unstable modes that appear as a consequence of undesired low-frequency interactions at the offshore grid. As far as the authors know, an eigenvalue-based stability assessment of an OWPP with an MMC-HVDC connection is a topic rarely or never explored in the literature before since a detailed time-invariant state-space model of the MMC was not available until recently. Thus, the eigenvalue-based stability study is the main contribution of this paper. The developed model can easily be extended to more complex OWPPs with different configurations in future works. Another contribution of this paper is the proposal of an adaptation to the MMC's grid-following state-space model so that the converter's dynamics in grid-forming mode can be represented. Finally, various studies are presented to prove that the adopted MMC's approximated model is accurate enough for small-signal stability analyses.</p