Genotoxic effect of nickel chloride and zinc sulphate on fish Hypophthalmichthys molitrix

The present investigation is to assess the genotoxic potential of nickel chloride and zinc sulphate on gill cells of silver carp Hypophthalmichthys molitrix. Fishes were exposed in sublethal concentration of nickel chloride 5. 7 mg/1 and zinc sulphate 6.8 mg/1, and sampled at 10, 20 and 30 days. Nickel chloride and zinc sulphate treated fishes exhibited an apparent increase in the aberration frequency and a decrease in the mitotic index as compared to control. Acentric fragment, chromatid break, endoreduplication, chromatid gap, centromeric fusion, ploidy, sticky plate, dicentric chromosome, clumping and partial sticky plates were some of the abnormalities observed. The chromosomal aberrations in the treated fishes were significant compared to control

Generators for the Algebra of Symmetric Functions

The algebra of symmetric functions contains several interesting families of symmetric functions indexed by integer partitions or skew partitions. Given a sequence $\{u_n\}$ of symmetric functions taken from one of these families such that $u_n$ is homogeneous of degree $n$, we provide necessary and sufficient conditions for the sequence to form a system of algebraically independent generators for the algebra of symmetric functions.Comment: 18 pages, Comments are welcom

Electrochemistry at nanoscale electrodes : individual single-walled carbon nanotubes (SWNTs) and SWNT-templated metal nanowires

Individual nanowires (NWs) and native single-walled carbon nanotubes (SWNTs) can be readily used as well-defined nanoscale electrodes (NSEs) for voltammetric analysis. Here, the simple photolithography-free fabrication of submillimeter long Au, Pt, and Pd NWs, with sub-100 nm heights, by templated electrodeposition onto ultralong flow-aligned SWNTs is demonstrated. Both individual Au NWs and SWNTs are employed as NSEs for electron-transfer (ET) kinetic quantification, using cyclic voltammetry (CV), in conjunction with a microcapillary-based electrochemical method. A small capillary with internal diameter in the range 30–70 μm, filled with solution containing a redox-active mediator (FcTMA+ ((trimethylammonium)methylferrocene), Fe(CN)64–, or hydrazine) is positioned above the NSE, so that the solution meniscus completes an electrochemical cell. A 3D finite-element model, faithfully reproducing the experimental geometry, is used to both analyze the experimental CVs and derive the rate of heterogeneous ET, using Butler–Volmer kinetics. For a 70 nm height Au NW, intrinsic rate constants, k0, up to ca. 1 cm s–1 can be resolved. Using the same experimental configuration the electrochemistry of individual SWNTs can also be accessed. For FcTMA+/2+ electrolysis the simulated ET kinetic parameters yield very fast ET kinetics (k0 > 2 ± 1 cm s–1). Some deviation between the experimental voltammetry and the idealized model is noted, suggesting that double-layer effects may influence ET at the nanoscale

Sociobiological Control of Plasmid copy number

Background:
All known mechanisms and genes responsible for the regulation of plasmid replication lie with the plasmid rather than the chromosome. It is possible therefore that there can be copy-up mutants. Copy-up mutants will have within host selective advantage. This would eventually result into instability of bacteria-plasmid association. In spite of this possibility low copy number plasmids appear to exist stably in host populations. We examined this paradox using a computer simulation model.

Model:
Our multilevel selection model assumes a wild type with tightly regulated replication to ensure low copy number. A mutant with slightly relaxed replication regulation can act as a “cheater” or “selfish” plasmid and can enjoy a greater within-host-fitness. However the host of a cheater plasmid has to pay a greater cost. As a result, in host level competition, host cell with low copy number plasmid has a greater fitness. Furthermore, another mutant that has lost the genes required for conjugation was introduced in the model. The non-conjugal mutant was assumed to undergo conjugal transfer in the presence of another conjugal plasmid in the host cell.

Results:
The simulatons showed that if the cost of carrying a plasmid was low, the copy-up mutant could drive the wild type to extinction or very low frequencies. Consequently, another mutant with a higher copy number could invade the first invader. This process could result into an increasing copy number. However above a certain copy number within-host selection was overcompensated by host level selection leading to a rock-paper-scissor (RPS) like situation. The RPS situation allowed the coexistence of high and low copy number plasmids. The non-conjugal “hypercheaters” could further arrest the copy numbers to a substantially lower level.

Conclusions:
These sociobiological interactions might explain the stability of copy numbers better than molecular mechanisms of replication regulation alone

Investigation of Wear Behaviour of Al6061 reinforcement with TiC and MoS2

Metal matrix composite (MMC) focuses primarily on improved specific strength, high temperature and wear resistance application. Aluminum matrix reinforced with titanium carbide and molybdenum disulfide has good potential and also self-lubrication. The main challenge is to produce this composite in a cost effective way to meet the above requirements. In this study Al–TiC-MoS2 castings with different volume fraction of TiC and MoS2 were produced in an argon atmosphere by an enhanced stir casting method. Hardness of the composite has increased with higher % of TiC addition. At that same time self-lubrication of composite has occur in the effort of MoS2. Dry sliding wear behavior of AMC was analyses with the help of a pin on disc wear and friction monitor. The present analyses reveal the improved hardness  as well as wear resistance

Strain Rate Dependent Behavior of Glass/Nano Clay Filled Epoxy Resin Composite

It is believed that addition of small amount of nanoclays in the neat epoxy and fiber reinforced epoxy composite system can improve the mechanical properties. The mechanical properties of most of polymer matrix composites are sensitive to testing rate. However, most of the researches were concentrated on the behavior of the polymermatrix composites at high strain rates. The present research work is to investigate the role of clay on neat epoxy and glass–fiber reinforced epoxy composites, at low strain rates. The clay in terms of 1.5 wt%, 3 wt%, and 5 wt% are dispersed in the epoxy resin using mechanical stirring followed by sonication process. The corresponding glass/epoxy nanocomposites are prepared by impregnating the clay epoxy mixture by hand lay-up process. Characterization of the nanoclay is done by X-ray diffraction and Scanning Electron Microscopy. Tensile stress-strain curves are obtained at strain rates of 10-4 s-1, 10-3 s-1, 10-2 s-1, and 10-1 s-1 by a hydraulic  machine reporting that, even at low strain rates, the longitudinal strength and stiffness increase as strain rate increases for all clay loadings. It is observed that the tensile modulus increases as the clay loading increases for both epoxy and glass/epoxy nanocomposites. It is also noticed that the longitudinal tensile strength decreases as the clay loading increases. The failed specimens show marked changes in the fracture surface with increased strain rate. Scanning electron microscopy is used to study the fiber/matrix/clay adhesion in fracture surfaces.Defence Science Journal, Vol. 64, No. 3, May 2014, pp. 295-302, DOI:http://dx.doi.org/10.14429/dsj.64.733

Urinary tract infection and its impact on sexual health

A sexual dysfunction and lower urinary tract symptoms have been a hot issue in recent years for scientists to study. There have been several clinical epidemiologic studies conducted in order to examine the connections between these two seemingly unrelated areas of urology research. In this review, an attempt is made to address these two sectors, their influence on patients’ quality of life, shared pathophysiological processes, and therapeutic features. Many urological patients suffer from both conditions, which are widespread in the general community. Phosphodiesterase type 5 inhibitors, the generally accepted combo therapy in this situation, sparked interest in finding alternative therapeutic choices

Covering Numbers of Some Irreducible Characters of the Symmetric Group

The covering number of a non-linear character $\chi$ of a finite group $G$ is the least positive integer $k$ such that every irreducible character of $G$ occurs in $\chi^k$. We determine the covering numbers of irreducible characters of the symmetric group $S_n$ indexed by certain two-row partitions (and their conjugates), namely $(n-2,2)$ and $((n+1)/2, (n-1)/2)$ when $n$ is odd. We also determine the covering numbers of irreducible characters indexed by certain hook-partitions (and their conjugates), namely $(n-2,1^2)$, the almost self-conjugate hooks $(n/2+1, 1^{n/2-1})$ when $n$ is even, and the self-conjugate hooks $((n+1)/2, 1^{(n-1)/2})$ when $n$ is odd.Comment: 33 page

Combinatorial inhibition of Angiotensin converting enzyme, Neutral endopeptidase and Aminopeptidase N by N-methylated peptides alleviates blood pressure and fibrosis in rat model of dexamethasone-induced hypertension

Angiotensin converting enzyme (ACE), neutral endopeptidase (NEP) and aminopeptidase N (APN) are responsible for generation of vasoactive peptides that regulates vasoconstriction, vasodilation and natriuresis, which altogether regulate blood pressure. Cumulative inhibition of ACE, NEP and APN effectively blocks the progression of respective pathways. In this study, N-methylated peptide inhibitors F-N(Me)H-L, V-N(Me)F-R and R-N(Me)V-Y were synthesized against ACE, NEP and APN respectively, using their respective physiological substrates. F-N(Me)H-L inhibited ACE activity with an IC50 of 83 nmol/L, V-N(Me)F-R inhibited NEP activity with an IC50 of 1.173 mu mol/L and R-N(Me)V-Y inhibited APN activity with an IC50 of 3.94 nmol/L respectively. Further, the anti-hypertensive effect of N-methylated peptides was evaluated using rat model of dexamethasone-induced hypertension. Individual peptides and their cocktail treatment were started from day 6 of the study period and blood pressure was measured on every alternate day during 15 day study. Administration of F-N(Me) H-L (138 +/- 3 mmHg) and cocktail of all the three peptides at a dose of 100 mg/kg significantly reduced systolic blood pressure (SBP) compared to dexamethasone group (SBP of Groups-dexamethasone; (167 +/- 5 mmHg), F-N (Me)H-L (138 +/- 3 mmHg), and Cocktail (122 +/- 3 mmHg). Anti-hypertensive, anti-hypertrophic and anti-fibrotic effects of N-methylated peptides and cocktail was further reflected by the decreased levels of circulating Ang II and increased ANP levels in sera of hypertensive rats along with decrease in collagen deposition in heart and kidney. Though, ACE inhibition is adequate to reduce SBP, targeting NEP and APN along with ACE is beneficial in tackling hypertension and associated fibrosis of heart

Ballistic Impact on Glass/Epoxy Composite Laminates

Glass/epoxy composite laminates are subjected to impact loading and the energy absorbing capacity of the laminates is studied. In the present study, laminates with four different orientations and thickness values are considered. Analytical study is carried out based on energy method and results are compared with FE results obtained from Abaqus/Explicit software. Results obtained from the analytical methods are showing good agreement with the FE results. It is found that cross-ply laminates are most efficient in ballistic resistance when compared with the laminates of other orientations. It is also noticed that the energy absorbing capacity is decreasing with increase in velocity of the projectile for a given lay-up and thickness value.Defence Science Journal, Vol. 64, No. 4, July 2014, pp. 393-399, DOI:http://dx.doi.org/10.14429/dsj.64.3882