A novel route for tethering graphene with iron oxide and its magnetic field alignment in polymer nanocomposites

We present a new route for tethering graphene nanoplatelets (GNPs) with Fe3O4 nanoparticles to enable their alignment in an epoxy using a weak magnetic field. The GNPs are first stabilised in water using poly(vinylpyrrolidone) (PVP) and Fe3O4 nanoparticles are then attached via coprecipitation. The resultant Fe3O4/PVP-GNPs nanohybrids are superparamagnetic and can be aligned in an epoxy resin, before gelation, by applying a weak magnetic field as low as 0.009 T. A theoretical model describing the alignment process is presented. The resulting nanocomposites exhibit anisotropic properties with significantly improved electrical conductivities (three orders of magnitude) in the alignment direction and dramatically increased fracture energy (about 530%) when the nanohybrids are aligned transverse to the crack growth direction, compared with the unmodified epoxy. Compared with the randomly-oriented nanocomposites, these aligned nanocomposites show approximately 50% increase in toughness transverse to the alignment direction and a seven-fold increase in electrical conductivity in the alignment direction

On the recent cyclone lashed across Gujarat coast and its effect on marine flsheries sector

A heavy cyclonic wind crossed the coastal Gujarat on 9-6-'98 resulting in the destruction of life and property besides total disruptions of communication, electricity and water supply systems. The present report summarises the effect of this cyclone on the marine fishery sector of coastal Gujarat

Epoxy nanocomposites containing magnetite-carbon nanofibers aligned using a weak magnetic field

Novel magnetite-carbon nanofiber hybrids (denoted by "Fe3O4@CNFs") have been developed by coating carbon nanofibers (CNFs) with magnetite nanoparticles in order to align CNFs in epoxy using a relatively weak magnetic field. Experimental results have shown that a weak magnetic field (∼50 mT) can align these newly-developed nanofiber hybrids to form a chain-like structure in the epoxy resin. Upon curing, the epoxy nanocomposites containing the aligned Fe3O4@CNFs show (i) greatly improved electrical conductivity in the alignment direction and (ii) significantly higher fracture toughness when the Fe3O4@CNFs are aligned normal to the crack surface, compared to the nanocomposites containing randomly-oriented Fe3O4@CNFs. The mechanisms underpinning the significant improvements in the fracture toughness have been identified, including interfacial debonding, pull-out, crack bridging and rupture of the Fe3O4@CNFs, and plastic void growth in the polymer matrix

Sudden emergence of fishery and some aspects of biology and population dynamics of Aluterus monoceros (Linnaeus, 1758) at Veraval

The sudden emergence of a fishery and selected aspects of biology and population dynamics of Aluterus monoceros landed by trawlers at Veraval was studied from January 2008 to December 2009. Total catch of 475 t recorded in September 2009, which increased to 7042 t in October dominated in the trawl landings with a contribution of 29.5%. However, in November and December, the catch decreased sharply to 1374 t and 94 t, respectively. The combined length-weight relationship was log W = -1.50 + 2.694 log L (r = 0.86) (n = 222) indicating allometric growth. Sex ratio was 1:1.05 (n = 129). Females attained sexual maturity at 50.2 cm total length. Zoobenthos, dominated by benthic invertebrates, cnidarians and worms, zooplankton dominated by copepods and nekton dominated by Acetes spp. and clupeid juveniles were the major food items of A. monoceros. The von Bertalanffy growth equation was Lt = 63.53 [1 – e - 0.22 (t + 0.077)]. Natural mortality, fishing mortality and exploitation ratio were 0.53, 0.58 and 0.52 respectivel

Improving the toughness and electrical conductivity of epoxy nanocomposites by using aligned carbon nanofibres

There is an increasing demand for high performance composites with enhanced mechanical and electrical properties. Carbon nanofibres offer a promising solution but their effectiveness has been limited by difficulty in achieving directional alignment. Here we report the use of an alternating current (AC) electric field to align carbon nanofibres in an epoxy. During the cure process of an epoxy resin, carbon nanofibres (CNFs) are observed to rotate and align with the applied electric field, forming a chain-like structure. The fracture energies of the resultant epoxy nanocomposites containing different concentrations of CNFs (up to 1.6wt%) are measured using double cantilever beam specimens. The results show that the addition of 1.6wt% of aligned CNFs increases the electrical conductivity of such nanocomposites by about seven orders of magnitudes to 10-2S/m and increases the fracture energy, GIc, by about 1600% from 134 to 2345J/m2. A modelling technique is presented to quantify this major increase in the fracture energy with aligned CNFs. The results of this research open up new opportunities to create multi-scale composites with greatly enhanced multifunctional properties

Using carbon nanofibre sensors for in-situ detection and monitoring of disbonds in bonded composite joints

This paper focuses on the ability of carbon nanofibre (CNF) networks to in situ monitor fatigue induced disbond damage in adhesive bonded composite joints. The inclusion of CNFs in the epoxy adhesive increases its conductivity by five orders of magnitude. The improved electrical conductivity is utilized to evaluate the ability of the CNF network to monitor and detect the fatigue induced disbond damage by measuring the in-situ resistance changes using a four probe setup. The changes in total resistance was a function of the bulk electrical resistivity of the adhesive and the bond dimensions, which were related to the disbond length to model and determine the size of the disbond. The simple resistivity model was in good agreement with the resistance measured during fatigue testing. Good agreement was found between the optical disbond observations and the disbond length calculated using the proposed model. Finite element simulations were performed to ascertain the range of applicability of the proposed model. The simplicity of the disbond detection technique via direct current potential drop technique enables real time monitoring of crack growth in the composite structure

Unusual landings of flying fish Cheilopogon furcatus(Mitchill, 1815) in Veraval, Mangrol and Chorwad

Flying fish, locally called "Zeri" or Kunga" have been occassionally reported from different fish landing centres in Gujarat. They are tropical oceanic pelagic fish which migrate and aggregate in the near shore areas for spawning

Identification of the Range of Nursing Skills Used to Provide Social Support for Mothers of Preterm Infants in Neonatal Intensive Care

Background. Hospitalization of preterm infants in neonatal intensive care units (NICUs) is a stressful experience for parents. Iranian NICUs do not have specified levels of care, nor do they integrate supportive methods of parent support such as family-centered care approaches. This study investigated the range and types of neonatal nursing support, as perceived by mothers of preterm infants, and its association with mothers’ satisfaction with infant care in the NICU. Methods. This is a descriptive, correlational study of mothers of preterm infants who were hospitalized in three different NICUs in Iran. A convenience sampling method was used. Data were collected using three questionnaires that identified (i) demographic information; (ii) social support available; and (iii) parent satisfaction with infant care. Results. Mothers (N = 110) generally rated the support from nurses as being moderate. Correlation analysis identified a moderate association of neonatal nurse social support domains for affirmational (r = 0.44) and concrete aid (r = 0.41), a moderately strong association for affectional support (r = 0.64), and total social support (r = 0.60) with mothers’ satisfaction. Conclusion. There were positive associations between social support from nurses and mothers’ satisfaction with the care of their infants. Therefore, planning to promote and create opportunities for neonatal nurses to support mothers in NICU is important to promote increased maternal satisfaction in infant care

Allosteric effects in cyclophilin mutants may be explained by changes in nano-microsecond time scale motions

The relationship between molecular motion and catalysis in enzymes is debated. Here, simulations of cyclophilin A and three catalytically-impaired mutants reveal a nanosecond-scale interconversion between active and inactive conformations, orders of magnitude faster than previously suggested