A new look at the modified Coulomb potential in a strong magnetic field

The static Coulomb potential of Quantum Electrodynamics (QED) is calculated in the presence of a strong magnetic field in the lowest Landau level (LLL) approximation using two different methods. First, the vacuum expectation value of the corresponding Wilson loop is calculated perturbatively in two different regimes of dynamical mass $m_{dyn.}$, {\it i.e.}, $|{\mathbf{q}}_{\|}^{2}|\ll m_{dyn.}^{2}\ll |eB|$ and $m_{dyn.}^{2}\ll |\mathbf{q}_{\|}^{2}|\ll|eB|$, where $\mathbf{q}_{\|}$ is the longitudinal components of the momentum relative to the external magnetic field $B$. The result is then compared with the static potential arising from Born approximation. Both results coincide. Although the arising potentials show different behavior in the aforementioned regimes, a novel dependence on the angle $\theta$ between the particle-antiparticle's axis and the direction of the magnetic field is observed. In the regime $|{\mathbf{q}}_{\|}^{2}|\ll m_{dyn.}^{2}\ll |eB|$, for strong enough magnetic field and depending on the angle $\theta$, a qualitative change occurs in the Coulomb-like potential; Whereas for $\theta=0,\pi$ the potential is repulsive, it exhibits a minimum for angles $\theta\in]0,\pi[$.Comment: V1: 26 pages, 8 figures, latex format, V2: Accepted for publication in PRD (2007

Optimization and validation of a method for extraction and quantification of ochratoxin A in black pepper

Abstract The extraction method for the determination of ochratoxin A (OTA) in black pepper was optimized. The influence of three variables, i.e., type of solvent, solvent-volume-to-samplesize ratio (v/w) and amount of sodium chloride (NaCl) (g), on OTA recovery was evaluated. Analysis of variance was used to compare recovery values obtained from different solvents, and response surface methodology (RSM) was used to determine the optimum amount of NaCl and the solvent-volume-to-sample-size ratio. The concentration of OTA was determined by high-performance liquid chromatography with fluorescence detection. The highest recovery (95.2 %) was obtained when methanol/water (80:20, v/v) was used as the solvent. The RSM results showed that the experimental data could be adequately fitted to a second-order polynomial model with multiple regression coefficients (R 2 ) of 0.962. The optimum amount of NaCl was determined to be 3 g, whereas the optimum solvent-volume-to-sample-size ratio (v/w) was found to be 4. The proposed method was applied to 20 samples, and the presence of OTA was found in 8 (40%) samples ranging from 0.11 to 3.16 ng g -1

Comparison of Propolis and Calcium Hydroxide in terms of Mineralization and Cytotoxicity Using Dental Pulp Stem Cells

Objectives: This study aimed to compare the in vitro cytotoxic activity of propolis, a bioactive material made by the honeybee, and calcium hydroxide (CH) and their effect on formation of mineralized nodules by human dental pulp stem cells (HDPSCs).Methods: In this in vitro study, HDPSCs were obtained from the Cellular and Molecular Oral Biology Laboratory of School of Dentistry, Shahid Beheshti University of Medical Sciences. In order to evaluate the proliferative effect of propolis and CH, HDPSCs were incubated with different concentrations of propolis (0-32mg/mL) and CH (0-4.8 mg/mL). Twenty-four and 48 hours later, the methylthiazolyl diphenyl-tetrazolium bromide (MTT) assay was carried out to evaluate the proliferation potential and viability of HDPSCs treated with propolis and CH. The effect of propolis and CH on mineralization of HDPSCs was assessed by alizarin red staining.Results: The MTT assay revealed that propolis at its highest concentration caused the greatest proliferation after 24 and 48 hours. Alizarin test showed that the lowest concentrations of CH and propolis at 14 days induced the formation of calcium nodules but at 21 days, propolis was deposited on the cells and calcification was not well recognizable.Conclusion: Propolis led to higher cell vitality at all concentrations in comparison to CH. However, due to its deposition on the cells, its effects on mineralization at 48 hours could not be determined

Obstacles and Challenges in the Use of Probiotics

BACKGROUND AND OBJECTIVE: Probiotics are living microorganisms whose adequate intake has shown healthful effects in the host body and have been suggested to have beneficial effects in the prevention and treatment of many diseases. This study was conducted to investigate the obstacles and challenges of probiotic products in the production process and their effects on human health. METHODS: For data collection in this review article, articles containing one of the terms “probiotic”, “lactobacillus”, “bifidobacterium”, “biogenic amine” and “antibiotic resistance” from 1990 to 2017 were searched and reviewed at Thomson Reuters, Pubmed, Scopus, Science Direct and Islamic World Science Citation Center(ISC). FINDING: Research has shown that systematic infections and chronic diseases, over-stimulation of the immune system, transfer of antibiotic resistance genes, production of biogenic amines and D-lactic acidosis, lack of survival and sustainability of microorganisms and ultimately the change in the taste and flavor of probiotic products are among the obstacles and challenges facing the production of probiotics. The use of bifidobacterium to transfer antibiotic resistance genes is safer than other microorganisms for the production of probiotic products. CONCLUSION: Based on the results of this study, probiotics are only safe in healthy people, although they are very useful for human health, but their use in children, pregnant women and people with a weakened immune system causes infection

GenoMetric Query Language: A novel approach to large-scale genomic data management

Motivation: Improvement of sequencing technologies and data processing pipelines is rapidly providing sequencing data, with associated high-level features, of many individual genomes in multiple biological and clinical conditions. They allow for data-driven genomic, transcriptomic and epigenomic characterizations, but require state-of-the-art ‘big data’ computing strategies, with abstraction levels beyond available tool capabilities. Results: We propose a high-level, declarative GenoMetric Query Language (GMQL) and a toolkit for its use. GMQL operates downstream of raw data preprocessing pipelines and supports queries over thousands of heterogeneous datasets and samples; as such it is key to genomic ‘big data’ analysis. GMQL leverages a simple data model that provides both abstractions of genomic region data and associated experimental, biological and clinical metadata and interoperability between many data formats. Based on Hadoop framework and Apache Pig platform, GMQL ensures high scalability, expressivity, flexibility and simplicity of use, as demonstrated by several biological query examples on ENCODE and TCGA datasets. Availability and implementation: The GMQL toolkit is freely available for non-commercial use at http://www.bioinformatics.deib.polimi.it/GMQL/. Contact: [email protected] Supplementary information: Supplementary data are available at Bioinformatics online

The effect of Pogostone on viability, membrane integrity, and apoptosis of liver cancer cells

OBJECTIVE: The incidence of liver cancer is still high in many countries, including Iran. Drug resistance and various side effects are the main obstacles to treating this cancer. Herbs, which are traditionally used, are now widely regarded as treatment options for cancer. Pogostone is a natural substance isolated from Indian mint (Pogostemon cablin) and has various medicinal activities. This study aimed to determine the effect of Pogostone on liver cancer cell line (viability, membrane integrity, and apoptosis). MATERIALS AND METHODS: The liver cancer cell line was prepared from Pasteur Institute of Iran and treated with appropriate concentrations of Pogostone. Cytotoxicity was determined by MTT, trypan blue, and lactate dehydrogenase assay. Apoptosis induction was evaluated by diphenylamine assay, Annexin V-FITC staining and a Real-time PCR test. Data were analyzed by SPSS statistical software using Tukey’s test one-way analysis of variance. RESULTS: After all three time periods, a significant decrease in viability was observed (p <0.05) in a concentration- and time-dependent manner. The cytotoxicity of Pogostone to liver cancer cells was in a concentration- and time-dependent manner. Pogostone significantly induced apoptosis compared to control cells (p<0.05). Treatment of liver cancer cells with Pogostone significantly reduced Bcl-2 gene expression (p<0.05). On the other hand, expression of all three Bax, p53, and caspase 3 genes showed a significant increase after treatment (p<0.05). CONCLUSIONS: Pogostone had a concentration- and time-dependent toxic effect on liver cancer cells. It induced apoptosis by increasing the Bax to Bcl-2 ratio