Effect of Electron Beam Irradiation on Survival of Brucella spp. in Traditional Ice Cream

Irradiation is a new technology which can be used for foods especially for the ones which common methods such as thermal method cannot be applied. Traditional ice cream samples were purchased from a local market. After applying a 15 kGy dose for sterilization, Brucella abortus and Brucella melitensis were inoculated to samples and then treated with four doses of 1, 2, 3 and 5 kGy electron beam irradiation at −18C storage temperature. Microbial examinations were performed in 3, 7, 14 and 21 days after treatment with electron beam irradiation. Results showed that no bacteria were observed in the initial test after use of 5 kGy dose. Applying 2 and 3 kGy reduced significantly (P < 0.05) the microbial population but could not eliminate it completely. This study confirmed that electron beam irradiation is a reliable way to reduce microbial population of Brucella spp. in traditional ice cream and therefore improve food safety. Practical Applications: To maintain palatability of traditional ice cream, milk must not be too heated or else pasteurization is not achieved. So, electron beam irradiation could ensure the safety of ice cream, instead of heat treatment. © 2015 Wiley Periodicals, Inc

Apex Exponents for Polymer--Probe Interactions

We consider self-avoiding polymers attached to the tip of an impenetrable probe. The scaling exponents $\gamma_1$ and $\gamma_2$, characterizing the number of configurations for the attachment of the polymer by one end, or at its midpoint, vary continuously with the tip's angle. These apex exponents are calculated analytically by $\epsilon$-expansion, and numerically by simulations in three dimensions. We find that when the polymer can move through the attachment point, it typically slides to one end; the apex exponents quantify the entropic barrier to threading the eye of the probe

Viral self-assembly as a thermodynamic process

The protein shells, or capsids, of all sphere-like viruses adopt icosahedral symmetry. In the present paper we propose a statistical thermodynamic model for viral self-assembly. We find that icosahedral symmetry is not expected for viral capsids constructed from structurally identical protein subunits and that this symmetry requires (at least) two internal "switching" configurations of the protein. Our results indicate that icosahedral symmetry is not a generic consequence of free energy minimization but requires optimization of internal structural parameters of the capsid proteins.Comment: pdf file, 13 pages, three figure

pH-Responsive PVA-Based Nanofibers Containing GO Modified with Ag Nanoparticles: Physico-Chemical Characterization, Wound Dressing, and Drug Delivery

Site-specific drug delivery and carrying repairing agents for wound healing purposes can be achieved using the intertwined three-dimensional structure of nanofibers. This study aimed to optimize and fabricate poly (vinyl alcohol) (PVA)-graphene oxide (GO)-silver (Ag) nanofibers containing curcumin (CUR) using the electrospinning method for potential wound healing applications. Fourier Transform Infrared (FTIR) spectrophotometry, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and zeta potential were used to characterize the nanostructures. The mechanical properties of the nanostructures were subsequently examined by tensile strength and elongation test. As shown by MIC analysis of E. coli and S. aureus bacteria, the fabricated nanofibers had superior inhibitory effects on the bacteria growth. Ag nanoparticles incorporation into the nanofibers resulted in increased loading and encapsulation efficiencies from 21% to 56% and from 61% to 86%, respectively. CUR release from PVA/GO-Ag-CUR nanofiber at pH 7.4 was prevented, while the acidic microenvironment (pH 5.4) increased the release of CUR from PVA/GO-Ag-CUR nanofiber, corroborating the pH-sensitivity of the nanofibers. Using the in vitro wound healing test on NIH 3T3 fibroblast cells, we observed accelerated growth and proliferation of cells cultured on PVA/GO-Ag-CUR nanofibers

Anticancer activity of Sargassum oligocystum water extract against human cancer cell lines

Background and Objectives: Antitumor drug resistance and side effects of antitumor compounds are the most common problems in medicine. Therefore, finding new antitumor agents with low side effects could be interesting. This study was designed to assay antitumor activity of the extract from brown alga Sargassum oligocystum, gathered from Persian Gulf seashore, against K562 and Daudi human cancer cell lines. Materials and Methods: The research was performed as an in vitro study. The effect of the alga extract on proliferation of cell lines were measured by two methods: MTT assay and trypan blue exclusion test. Results and Conclusion: The most effective antitumor activity has been shown at concentrations 500 μg/ml and 400 μg/ml of the alga extract against Daudi and K562 cell lines, respectively. The results showed that the extracts of brown alga Sargassum oligocystum have remarkable antitumor activity against K562 and Daudi cell lines. It is justified to be suggested for further research such as algal extract fractionation and purification and in vivo studies in order to formulate natural compounds with antitumor activities

Optical spectra and thermal Schottky levels in dysprosium sesquisulfide

We report a detailed crystal-field splitting analysis of the energy levels of Dy3+(4f9)Dy3+(4f9) in single crystals of Dy2S3Dy2S3 that have the Th3P4Th3P4 cubic defect structure. From an analysis of the temperature-dependent absorption spectra, we have identified seven of the eight crystal-field split energy (Stark) levels of the ground-state multiplet manifold, 6H15/2.6H15/2. Sixty-two experimental Stark levels from various multiplet manifolds of Dy3+Dy3+ are compared with a calculated crystal-field splitting, whose initial crystal-field parameters, Bnm,Bnm, were determined from lattice-sum calculations. The rms deviation between experimental and calculated levels is 7 cm−1. Both the experimental and calculated crystal-field splitting of the 6H15/26H15/2 manifold are compared with an assignment of Schottky levels obtained from a reassessment of heat capacity data reported earlier. Based on entropy considerations and verification of the Schottky level assignments by analyses of the optical and magnetic susceptibility data, we conclude that the anomaly observed in the heat capacity data near 3.4 K is due to antiferromagnetic ordering. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69677/2/JCPSA6-110-24-12125-1.pd

Antiviral activity of Holothuria sp. a sea cucumber against herpes simplex virus type 1 (HSV-1)

BACKGROUND: Finding the new bioactive compounds with antiviral activity from the natural resources are in interest of many drug discovery scientists. Sea cucumber is among the marine organisms a traditional food item in Asia with different applications in traditional medicine. METHODS: In current study, a cold water extract of the Holothuria sp, one type Persian Gulf’s sea cucumber was evaluated for its antiviral effects against KOS strain of Herpes Simplex Virus tyoe 1 (HSV-1) in cell culture. The half maximal inhibitory concentration (IC50) values were calculated for anti-adsorption activity and intracellular antiviral activity of the crude extract separately. RESULTS: The extract exhibited antiviral activity not only against the virus adsorption to the cells, but also on virus intracellular replication.The CC50 for sea cucumber extract was 32.57 mg/ml. The IC50 values for the inhibition of the virus adsorption to the cells and virus intracellular replication were 120.2 and 189.9 μg/ml respectively. Selectivity index (SI) value for anti-adsorption activity was 189 while that value for the extract’s intracellular antiviral activity was 172. CONCLUSIONS: The results showed that Holothuria sp, water extract has remarkable antiviral effect against HSV-1 in cell culture and it is crucial to investigate the mechanism(s) of action of extract. Moreover, identification of the effective compound(s) within the extract would be necessary for future studies towards developing the new natural antiviral agent against HSV-1

Dynamic Pathways for Viral Capsid Assembly

We develop a class of models with which we simulate the assembly of particles into T1 capsid-like objects using Newtonian dynamics. By simulating assembly for many different values of system parameters, we vary the forces that drive assembly. For some ranges of parameters, assembly is facile, while for others, assembly is dynamically frustrated by kinetic traps corresponding to malformed or incompletely formed capsids. Our simulations sample many independent trajectories at various capsomer concentrations, allowing for statistically meaningful conclusions. Depending on subunit (i.e., capsomer) geometries, successful assembly proceeds by several mechanisms involving binding of intermediates of various sizes. We discuss the relationship between these mechanisms and experimental evaluations of capsid assembly processes.Comment: 13 pages, 13 figures. Submitted to Biophys.

In vitro antitumor activity of Gracilaria corticata (a red alga) against Jurkat and molt-4 human cancer cell lines

Gracilaria corticata is a red alga which can be collected from many sea coasts around the world such as China, India, Persian Gulf, etc. The Persian Gulf is a unique marine habitat infested with diverse seaweeds. The aim of the present study is to explore anticancer potential of the crude extracts from G. corticata which was collected from the Bushehr coast (South west of Iran). Here, different concentration of the aqueous extract from G. corticata was tested for probable antitumoral activity on Jurkat and molt- 4 human lymphoblastic leukemic cell lines. The cells were treated by different concentration of algal extract and the number of viable cells was determined by trypan blue. Also, cytotoxicity of the extract was evaluated by methyl thiazolyl tetrazolium (MTT) assay. The results showed that 9.336 and 9.726 μg/μl of algal extract were the most effective concentrations against Jurkat and molt-4 cells, respectively. The water crude extract of red alga G. corticata had significant anticancer activity and it might be a good candidate for further investigations in order to develop a natural compound as an anticancer agent which can be used for the production of potential anticancer drug and novel pharmaceutical leads.Key words: Gracilaria corticata, anticancer, Jurkat, molt-4