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Microstructural design is a widespread approach to tailor the properties of functional materials with the size effect being an effective constraint that modifies physical phenomena. In this work, we investigate the grain size effect on the properties and the electric field induced phase transformation behavior in barium titanate. A broad range of unimodal average grain size distribution between 0.4 and 15 μm was successfully sintered avoiding abnormal grain growth. Samples with a grain size close to the range of 1–2 μm, balancing microstructural strain, presence, and mobility of domain walls to allow the field induced crystal phase transformation, showed optimal electromechanical and dielectric properties. By means of in situ high energy x-ray diffraction and a high-resolution multianalyzer detector, we distinguish and quantify a tetragonal–orthorhombic phase transformation induced by an electric field, providing unambiguous proof of this induced phase transformation. These results contribute to the understanding of fundamental questions about the piezoelectric effect in barium titanate and consequently other similar systems. [ABSTRACT FROM AUTHOR]

BiFeO3–BaTiO3 (BF–BT) solid solutions exhibit great promise as the basis for high temperature piezoelectric transducers and energy storage dielectrics, but the fundamental mechanisms governing their functional properties require further clarification. In the present study, both pure and niobium-doped 0.7BF–0.3BT ceramics are synthesized by solid state reaction and their structure–property relationships are systematically investigated. It is shown that substituting a low concentration of Ti with Nb at a level of 0.5 at% increases the resistivity of BF–BT ceramics and facilitates ferroelectric switching at high electric field levels. Stable planar piezoelectric coupling factor values are achieved with a variation from 0.35 to 0.45 over the temperature range from 100 to 430 °C. In addition to the ferroelectric-paraelectric phase transformation at the Curie point (∼430 °C), a frequency-dependent relaxation of the dielectric permittivity and associated loss peak are observed over the temperature range from −50 to +150 °C. These effects are correlated with anomalous enhancement of the remanent polarization and structural (rhombohedral) distortion with increasing temperature, indicating the occurrence of a re-entrant relaxor ferroelectric transformation on cooling. The results of the study provide new insight into the thermal evolution of structure and the corresponding functional properties in BF–BT and related solid solutions. [ABSTRACT FROM AUTHOR]

Bending strength of commercially relevant lead‐free piezoceramics – 0.935Na0.5Bi0.5TiO3‐0.065BaTiO3 (NBT‐6.5BT) with and without acceptor Zn‐doping and 0.92(K0.5Na0.5)NbO3‐0.02(Bi0.5Li0.5)TiO3‐xBaZrO3; x = 0.06, 0.07 (KNN‐BZ100x) have been quantified using 4‐point bending tests and contrasted to that of commercial lead zirconate titanate (PZT, PIC151). The compressive and tensile strength probed using additional strain gauges under 4‐point bending indicate negligible non‐linear deformation, in stark contrast to that of commercial PIC151. The bending strength of KNN‐BZ100x is about 100 MPa, comparable to PIC151, while that of NBT‐6.5BT‐based materials is about twice that of PIC151 at ∼160 MPa. These results are rationalized based on the intrinsic characteristics of the lead‐free piezoceramics in terms of fracture toughness, coercive stress, and Young's modulus. Weibull statistics indicate a higher fracture probability for KNN‐based materials, with NBT‐6.5BT‐based materials featuring Weibull modulus twice that of KNN‐based materials. [ABSTRACT FROM AUTHOR]

A series of morphotropic phase boundary (MPB) compositions of (1–x)Na1/2Bi1/2TiO3‐xBaTiO3 (x = 0.05, 0.055, 0.06, 0.065, 0.07), with and without 0.5 mol% Zn‐doping was synthesized using the solid‐state route. The samples were characterized using X‐ray diffraction, dielectric analysis, and electromechanical measurements (piezoelectric d33 coefficient, coupling factor kp, mechanical quality factor Qm, and internal bias field Ebias). The increase in the ferroelectric‐relaxor transition temperature upon Zn‐doping was accompanied by a shift of the MPB toward the Na1/2Bi1/2TiO3‐rich side of the phase diagram. Higher tetragonal phase fraction and increased tetragonal distortion were noted for Zn‐doped (1 – x)Na1/2Bi1/2TiO3‐xBaTiO3. In addition, ferroelectric hardening and the presence of an internal bias field (Ebias) were observed for all doped compositions. The piezoelectric constant d33 and the coupling coefficient kp decreased by up to ∼30%, while a 4‐ to 6‐fold increase in Qm was observed for the doped compositions. Apart from establishing a structure–property correlation, these results highlight the chemically induced shift of the phase diagram upon doping, which is a crucial factor in material selection for optimal performance and commercialization. [ABSTRACT FROM AUTHOR]

A series of morphotropic phase boundary (MPB) compositions of (1–x)Na1/2Bi1/2TiO3‐xBaTiO3 (x = 0.05, 0.055, 0.06, 0.065, 0.07), with and without 0.5 mol% Zn‐doping was synthesized using the solid‐state route. The samples were characterized using X‐ray diffraction, dielectric analysis, and electromechanical measurements (piezoelectric d33 coefficient, coupling factor kp, mechanical quality factor Qm, and internal bias field Ebias). The increase in the ferroelectric‐relaxor transition temperature upon Zn‐doping was accompanied by a shift of the MPB toward the Na1/2Bi1/2TiO3‐rich side of the phase diagram. Higher tetragonal phase fraction and increased tetragonal distortion were noted for Zn‐doped (1 – x)Na1/2Bi1/2TiO3‐xBaTiO3. In addition, ferroelectric hardening and the presence of an internal bias field (Ebias) were observed for all doped compositions. The piezoelectric constant d33 and the coupling coefficient kp decreased by up to ∼30%, while a 4‐ to 6‐fold increase in Qm was observed for the doped compositions. Apart from establishing a structure–property correlation, these results highlight the chemically induced shift of the phase diagram upon doping, which is a crucial factor in material selection for optimal performance and commercialization. [ABSTRACT FROM AUTHOR]

Quenching from sintering temperature enhances the depolarization temperature (Td) in Na1/2Bi1/2TiO3-based ceramics without significant deterioration of piezoelectric properties (d33). In this work, quenching effects in an ergodic relaxor 0.97(0.94Na0.5Bi0.5TiO3–0.06BaTiO3)–0.03AgNbO3 (NBT–6BT–3AN) were investigated based on structure, ferroelectric, and dielectric properties. The ergodicity to nonergodicity transition was obtained by quenching NBT–6BT–3AN above 1000 °C. The temperature stability of the quenching-induced nonergodicity was examined by annealing the quenched sample at 300 °C and 600 °C. The effect of oxygen vacancy on ergodicity to nonergodicity transition was investigated by comparing ferroelectric and electrostrain responses of the quenched and nitrogen-atmosphere-annealed samples. The influence of quenching on the structure including the average crystal structure, phase fraction and lattice distortion and the local structure including bond lengths and ordering of ions was analyzed. The ergodicity to nonergodicity transition upon quenching is ascribed to the contribution of the off-centered Bi3+ ions and ordered local structure. [ABSTRACT FROM AUTHOR]

We investigated 22 water samples (17 well water and five pipe water - both chlorinated) and six soil samples from the surroundings of wells of the households of suspected patients from Palakkad district, Kerala (India), from where a cholera outbreak was reported during June-July 2016. A total of 25 Vibrio cholerae isolates were collected from three well water samples during a recent cholera outbreak. Biochemical and serological studies revealed that all of the isolates belonged to serogroup O1, biotype El Tor, serotype Ogawa. PCR assays confirmed the occurrence of ctxB, ctxA, hlyA, tcpA El Tor,VPI, ace, zot, ompW, rfbO1 and toxR genes in all isolates. The presence of the ctxB gene of the classical biotype in all of the El Tor isolates suggests that it is a new variant of El Tor biotype. Antibiogram profile of all V. cholerae O1 isolates revealed resistance towards five classes of antibiotics island and indicates that they were multidrug resistant. ERIC-PCR and PFGE finger prints showed the clonal relationship among the V. cholerae O1 isolates. The results of this study revealed the emergence of a new variant of El Tor biotype in the water samples from Palakkad district, from where a cholera outbreak was reported. [ABSTRACT FROM AUTHOR]

Piezoelectric applications such as ultrasonic motors, transformers and therapeutic ultrasonics demand high power generation with low losses, which is facilitated by "hard" ferroelectrics. Hardening of piezoelectric properties, characterized by high mechanical quality factor (Qm), is usually achieved by doping with lower valence elements, thereby tailoring the domain wall dynamics. In the present study, we demonstrate a hardening mechanism by developing composites of 0.94(Na1/2Bi1/2)TiO3-0.06BaTiO3 (NBT-6BT) with ZnO inclusions, as an alternative to chemical modifications. A decrease in the saturation polarization and total strain, higher internal bias fields, lower hysteretic losses and a two-fold increase in Qm are observed in comparison to NBT-6BT. The composite with 0.1 mole ratio of ZnO exhibits the highest Qm of 320 with d33=125 pC/N and Kp=0.29. A one-to-one correspondence between the increase in Qm and the decrease in the domain wall mobility is established from the ac field dependence of permittivity, in the framework of the Rayleigh law. A further increase in ZnO content beyond a mole ratio of 0.1 reduces Qm, but retains it at a higher level, as compared to NBT-6BT. The results are explained based on the poling-induced strain incompatibility between the matrix and the hard ZnO phase. This composite approach is therefore considered a generic hardening concept and can be extended to other ferroelectric systems. [ABSTRACT FROM AUTHOR]

Methicillin-resistant Staphylococcus aureus (MRSA) has been a global health concern since the 1960s, and isolation of this pathogen from food-producing animals has been increasing. However, little information is available on the prevalence of MRSA and its clonal characteristics in seafood and the aquatic environment. In this study, 267 seafood and aquatic environment samples were collected from three districts of Kerala, India. Staphylococcal protein A (spa) typing and multilocus sequence typing (MLST) was performed for 65 MRSA strains isolated from 20 seafood and aquatic environment samples. The MRSA clonal profiles were t657-ST772, t002-ST5, t334-ST5, t311-ST5, t121-ST8, t186-ST88, t127-ST1, and two non-spa assignable strains. Whole spa gene sequence analysis along with MLST confirmed one strain as t711-ST6 and another as a novel MRSA clone identified for the first time in seafood and the aquatic environment with a t15669 spa type and a new MLST profile of ST420-256-236-66-82-411-477. The MRSA strains were clustered into five clonal complexes based on the goeBURST algorithm, indicating high diversity among MRSA strains in seafood and the aquatic environment. The novel clone formed a separate clonal complex with matches to three loci. This study recommends large-scale spa typing and MLST of MRSA isolates from seafood and the aquatic environment to determine the prevalence of new MRSA clones. This monitoring process can be useful for tracing local spread of MRSA isolates into the seafood production chain in a defined geographical area. [ABSTRACT FROM AUTHOR]

The lattice strain and domain switching behavior of xBiScO3-(1-x)PbTiO3 (x=0.40) was investigated as a function of cyclic field and grain orientation by in situ X-ray diffraction during application of electric fields. The electric field induced 200 lattice strain was measured to be five times larger than the 111 lattice strain in pseudorhombohedral xBiScO3-(1-x)PbTiO3 (x=0.40). It is shown that the anomalous 200 lattice strain is not an intrinsic phenomenon, but arises primarily due to stress associated with the reorientation of the 111 domains in dense polycrystalline ceramic. [ABSTRACT FROM AUTHOR]

In this stability-indicating, reversed-phase high-performance liquid chromato-graphic method for flupiritine maleate, forced degradation has been employed and the formed degradants were separated on a C18 column with a 80:20% v/v mixture of methanol-water containing 0.2% (v/v) triethylamine; the pH was adjusted to 3.1. The flow rate was 1 mLmin-1 and the photodiode array detection wavelength was 254 nm. Forced degradation of the drug was carried out under acidic, basic, thermal, photolytic, peroxide, and neutral conditions. Chromatographic peak purity data indicated no co-eluting peaks with the main peaks. This method resulted in the detection of seven degradation products (D1-D7). Among these, three major degradation products from acidic and basic hydrolysis were identified and characterized by 1H-NMR, 13C-NMR, and mass spectral data. The method was validated as per International Conference on Harmonization guidelines (Q2). The linearity of the method was in the concentration range of 20-120 μgmL-1. The relative standard deviations for intra- and interday precision were below 1.5%. The specificity of the method is suitable for the stability-indicating assay. [ABSTRACT FROM AUTHOR]

Piezoelectric and ex situ electric-field induced structural studies were carried out on closely spaced compositions in the morphotropic phase boundary region of (1--x) PbTiO3-(x)BiScO3. While the common approach of zero field structural analysis failed to provide a unique relationship between the anomalous piezoresponse of x = 0.3725 and structural factor(s), ex situ study of electric-field induced structural changes revealed that the composition exhibiting the highest piezoelectric response is the one which also exhibits significantly enhanced polarizability of the lattices of both coexisting (monoclinic and tetragonal) phases. The enhanced lattice polarizability manifests as a significant fraction of the monoclinic phase transforming irreversibly to the tetragonal phase after electric poling. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study that examines the non-radio-labeled probe-based colony blotting assay detection method for rapid enumeration of Salmonella serovars in seafood and water samples. The probe-based technique using a digoxigenin-based labeling assay is compared with the quantitative polymerase chain reaction (PCR) assay. the Salmonella in spiked seafood and water samples was successfully quantified by the assay.

Temperature dependent X-ray powder diffraction and dielectric studies have been carried out on tetragonal compositions of (1− x) PbTiO3-( x) BiMeO3; Me = Sc and Zn1/2 Ti1/2. The cubic and the tetragonal phases coexist over more than 100°C for 0.70 PbTiO3-0.3 Bi( Zn1/2 Ti1/2) O3 and 0.66 PbTiO3-0.34 BiScO3. The wide temperature range of phase coexistence is shown to be an intrinsic feature of the system, and is attributed to the increase in the degree of the covalent character of the ( Pb + Bi)- O bond with increasing concentration of Bi at the Pb-site. The d-values of the {111} planes of the coexisting phases are nearly identical, suggesting this plane to be the invariant plane for the martensitic type cubic-tetragonal transformation occurring in these systems. [ABSTRACT FROM AUTHOR]

Temperature dependent X-ray powder diffraction and dielectric studies have been carried out on tetragonal compositions of (1− x) PbTiO3-( x) BiMeO3; Me = Sc and Zn1/2 Ti1/2. The cubic and the tetragonal phases coexist over more than 100°C for 0.70 PbTiO3-0.3 Bi( Zn1/2 Ti1/2) O3 and 0.66 PbTiO3-0.34 BiScO3. The wide temperature range of phase coexistence is shown to be an intrinsic feature of the system, and is attributed to the increase in the degree of the covalent character of the ( Pb + Bi)- O bond with increasing concentration of Bi at the Pb-site. The d-values of the {111} planes of the coexisting phases are nearly identical, suggesting this plane to be the invariant plane for the martensitic type cubic-tetragonal transformation occurring in these systems. [ABSTRACT FROM AUTHOR]

A study to evaluate the influence of potassium sorbate combined with modified atmosphere packaging (MAP) at 2C on the shelf-life extension of seer fish (Scomberomorus commerson ) steaks was made. The shelf life of 12 days in air pack was extended by 10 and 18 days in MAP and modified-atmosphere-packed seer fish pretreated with potassium sorbate, respectively. K value was not a suitable predictor of shelf life for seer fish. Potassium sorbate treatment showed further inhibition of total aerobic mesophilic count while sulfite reducing clostridial counts were 1 log cfu/g in all the packs after day 12 of storage. Potassium sorbate treated MAP samples showed higher sensory score on day 25 than those observed for MAP (P < 0.05) and CMAP steaks. Significant extension (P < 0.05) in shelf life was noticed due to MAP and treating samples with potassium sorbate. PRACTICAL APPLICATIONS The present study suggests that modified atmosphere 70% CO2 : 30% O2 extended shelf life of seer fish by 10 days. By using 70% CO2 : 30% O2 with 2% potassium sorbate, the shelf life of seer fish was further extended by 18 days compared to air pack which served as control and this particular combination could be commercially exploited. As the optimal gas composition varies depending on the fish, this paper adds new research information on preservation of seer fish. Moreover, as seer fish has high export demand, proper preservation technique suggested in this paper is highly relevant. [ABSTRACT FROM AUTHOR]

The effect of sodium chloride concentration (3, 4, 5, 6, 8, 10 and 12%) and storage temperatures (4°C, 10°C, 15°C and 30°C) on toxin production by Clostridium, botulinum isolated from tropical fish was studied in anaerobic cooked meat medium. The combined effect of sodium chloride (3, 5%), low pH (5.5) and low temperature (15°C) on toxin production by C. botulinum was also examined. The toxicity was tested by mouse bioassay. An increase in lag phase was noticed by increasing the salt concentration. At 30°C, spores of C. botulinum type E were able to grow and produce toxin up to 3% salt (aw = 0.976), whereas for types C and D the limiting salt concentration was 4-5% (aw = 0.97-0.974) and for types A and B it was 8% (aw = 0.952). By lowering the storage temperature, an increase in lag phase and time to toxicity was noticed for type Eat 3% salt and for types A, C and D at 5% salt level. The probability of growth and toxin production at 5% salt decreased as the pH and storage temperature (combined stress) was decreased. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the microbiological quality of farmed giant freshwater prawn (Macrobrachium rosenbergii) collected from four freshwater farms located in Kerala (India). Microbiological counts on whole, deheaded, and deheaded and deveined prawn as well as on head and intestine were determined. Average counts (log10 cfu g-¹) on whole prawn were 6.9 (total mesophilic counts (TPC) at 37°C) and 4.1 (psychrotrophic count at 7°C). The results indicated that the aerobic counts were within the acceptable limit. The levels of enterococci and faecal coliforms in farmed M. rosenbergii were high. There was an increase in the numbers of enterococci and Staphylo- coccus aureus after deheading. The major groups of bacteria comprising the flora of M. rosenbergii were Aeromonadaceae, Enterobacteriaceae and Pseudo,nonas. Farmed M. rosenbergii carried pathogenic bacteria such as Enterococcus spp., S. aureus, Aeromonas hydrophila, A. veronii biovar sobria and Clostridium perfringens. The results of the study sug- gest adoption of good farming and post harvest practices to improve the microbiological quality of farmed freshwater prawn. [Article copies available [ABSTRACT FROM AUTHOR]

This study was undertaken to determine the influence of temperature and pH on growth and time to toxicity of spores of Clostridium botulinum types isolated from tropical fish. Anaerobic meat medium with varying temperatures (4-30°C) and pH values (4.5 to 7.0) were used and toxicity was tested by mouse bioassay. An increase in lag phase was noticed by lowering the growth temperature from 30°C to 4°C and the pH from 7.0 to 4.6. The probability of toxin production increased with storage time, but decreased as either the pH or storage temperature and pH (combined stress) was decreased. The results indicated the effect of pH in controlling toxin production by C. botulinum spores in refrigerated foods with pH 5.0 or < 5.0. [ABSTRACT FROM AUTHOR]

The sensitivity of Oreochromis mossambicus to Clostridium botulinum toxin types A–E was investigated. All five toxin types were toxic to O. mossambicus. In the case of toxin types A–D, O. mossambicus was considerably more resistant than mice and, in the case of type E toxin, fish were more sensitive. The minimum intraperitoneal (i.p.) dose of type E toxin for fish was half the minimum lethal dose for mice. The results of the study suggest that good hygiene should be maintained in fish/shrimp farms to keep contamination at a low level. [ABSTRACT FROM AUTHOR]

High-performance piezoelectric materials constantly attract interest for both technological applications and fundamental research. The understanding of the origin of the high-performance piezoelectric property remains a challenge mainly due to the lack of direct experimental evidence. We perform in situ high-energy x-ray diffraction combined with 2D geometry scattering technology to reveal the underlying mechanism for the perovskite-type lead-based high-performance piezoelectric materials. The direct structural evidence reveals that the electric-field-driven continuous polarization rotation within the monoclinic plane plays a critical role to achieve the giant piezoelectric response. An intrinsic relationship between the crystal structure and piezoelectric performance in perovskite ferroelectrics has been established: A strong tendency of electric-field-driven polarization rotation generates peak piezoelectric performance and vice versa. Furthermore, the monoclinic MA structure is the key feature to superior piezoelectric properties as compared to other structures such as monoclinic MB, rhombohedral, and tetragonal. A high piezoelectric response originates from intrinsic lattice strain, but little from extrinsic domain switching. The present results will facilitate designing high-performance perovskite piezoelectric materials by enhancing the intrinsic lattice contribution with easy and continuous polarization rotation. [ABSTRACT FROM AUTHOR]

Quorum sensing (QS) is a type of cell to cell communication in bacteria that can also regulate the virulence potential in pathogenic strains. Hence, QS disruption, i.e. the quorum quenching (QQ) mechanism, is presently being explored as a novel bio-control strategy to counter bacterial infections. In the present study, we characterized the QQ ability of Bacillus spp. strains to reduce the expression of some virulence factors of a shrimp pathogen, Vibrio harveyi. We screened a total of 118 spore-forming bacterial isolates from aquaculture ponds and mangrove soil for their ability to degrade the synthetic N-acyl-homoserine lactones (AHLs) C4-HSL, C6-HSL, C8-HSL, and C10-HSL. We then selected the top 17 isolates with high AHL-degradation ability for further study. Among them, B. subtilis MFB10, B. lentus MFB2, and B. firmus MFB7 had the highest ability for degradation. These 3 isolates suppressed the expression of virulence genes encoding protease, lipase, phospholipase, caseinase, chitinase, and gelatinase, and potentially inhibited the biofilm formation of V. harveyi MFB32. The reduction in expression of virulence genes like those coding for metalloprotease, serine protease, and haemolysin were confirmed by real-time PCR analysis. Moreover, in an in vivo challenge experiment, these Bacillus spp. protected Penaeus monodon post-larvae against V. harveyi MFB3 infection. Our results demonstrate the potential application of AHL-degrading Bacillus spp. as an alternative to antibiotics in shrimp hatcheries to control luminescent vibriosis. This novel bio-therapeutic method is a promising approach towards disease control in shrimp aquaculture.

Luminescent Vibrio harveyi is common in sea and estuarine waters. It produces several virulence factors and negatively affects larval penaeid shrimp in hatcheries, resulting in severe economic losses to shrimp aquaculture. Although V. harveyi is an important pathogen of shrimp, its pathogenicity mechanisms have yet to be completely elucidated. In the present study, isolates of V. harveyi were isolated and characterized from diseased Penaeus monodon postlarvae from hatcheries in Kerala, India, from September to December 2016. All 23 tested isolates were positive for lipase, phospholipase, caseinase, gelatinase and chitinase activity, and 3 of the isolates (MFB32, MFB71 and MFB68) showed potential for significant biofilm formation. Based on the presence of virulence genes, the isolates of V. harveyi were grouped into 6 genotypes, predominated by vhpA+ flaB+ ser+ vhh1- luxR+ vopD- vcrD+ vscN-. One isolate from each genotype was randomly selected for in vivo virulence experiments, and the LD50 ranged from 1.7 ± 0.5 × 103 to 4.1 ± 0.1 × 105 CFU ml-1. The expression of genes during the infection in postlarvae was high in 2 of the isolates (MFB12 and MFB32), consistent with the result of the challenge test. However, in MFB19, even though all genes tested were present, their expression level was very low and likely contributed to its lack of virulence. Because of the significant variation in gene expression, the presence of virulence genes alone cannot be used as a marker for pathogenicity of V. harveyi.

A disease outbreak in 42-d-old black tiger shrimp Penaeus monodon juveniles from a commercial aquaculture farm in Kerala, India, was investigated. The cause of the disease outbreak was confirmed as Vibrio parahaemolyticus by biochemical tests, PCR targeting the toxR gene and pathogenicity testing of the isolates. All of the isolates tested negative by PCR specific for V. parahaemolyticus associated with acute hepatopancreatic necrosis disease (AHPND), implicating vibriosis unrelated to AHPND as the cause of mortality. Among the 19 isolates obtained, 2 possessed the tdh gene (coding for thermo-stable hemolysin), whereas none of the isolates possessed trh. The LD50 value of 8 isolates of V. parahaemolyticus from diseased and apparently healthy shrimp ranged from 2.7 × 104 to 4.9 × 105 CFU ml-1 by immersion challenge of P. monodon postlarvae. BOX-PCR and dendrogram analysis of the bacterial isolates revealed that the isolates from moribund and apparently healthy shrimp formed separate clusters, indicating that these isolates originate from separate clones. The isolates from moribund shrimp including tdh-positive V. parahaemolyticus clustered together. The present study represents the first report of tdh-positive V. parahaemolyticus causing disease in a shrimp farm.

The prevalence of Listeria monocytogenes in the retail fish markets of the Kerala, India was investigated by screening 227 samples comprising of marine finfish (n = 97) shellfish (n = 19), ready-to-cook fish products (n = 47), ready-to-eat fish products (n = 10), dried fish (n = 11) and retail ice (n = 43). The prevalence of L. monocytogenes and L. innocua was 2·7% and 17·2% respectively. Sample category wise, prevalence of L. monocytogenes was higher in marine finfish (1·8%) and retail ice (0·9%). All the L. monocytogenes isolates carried virulent genes namely inlA, inlC, inlJ, hlyA, iap, plcA, prfA genes and majority (82%) belonged to 1/2a, 3a serogroups. L. monocytogenes isolates were multidrug-resistant and showed resistance to ampicillin, penicillin, erythromycin, tetracycline and clindamycin. Enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) delineated 58% genetic heterogeneity among the L. monocytogenes strains. The study reports that genetic similarities of the isolates were interlinked to their serogroup and sample origin. SIGNIFICANCE AND IMPACT OF THE STUDY: Prevalence of Listeria monocytogenes, in the retail fish markets of Kerala, India was low but their relatively higher presence in marine finfish and retail ice and virulent nature of the isolates signifies food safety concerns. Moreover, multidrug-resistant nature of these isolates may potentially lead to spread of antimicrobial resistance. This study identified retail ice as a vehicle for entry of L. monocytogenes in retail fish and hence, there is a need to ensure quality of retail ice used for maintaining the cold-chain., (© 2019 The Society for Applied Microbiology.)

High-performance piezoelectric materials constantly attract interest for both technological applications and fundamental research. The understanding of the origin of the high-performance piezoelectric property remains a challenge mainly due to the lack of direct experimental evidence. We perform in situ high-energy x-ray diffraction combined with 2D geometry scattering technology to reveal the underlying mechanism for the perovskite-type lead-based high-performance piezoelectric materials. The direct structural evidence reveals that the electric-field-driven continuous polarization rotation within the monoclinic plane plays a critical role to achieve the giant piezoelectric response. An intrinsic relationship between the crystal structure and piezoelectric performance in perovskite ferroelectrics has been established: A strong tendency of electric-field-driven polarization rotation generates peak piezoelectric performance and vice versa. Furthermore, the monoclinic M&#95;{A} structure is the key feature to superior piezoelectric properties as compared to other structures such as monoclinic M&#95;{B}, rhombohedral, and tetragonal. A high piezoelectric response originates from intrinsic lattice strain, but little from extrinsic domain switching. The present results will facilitate designing high-performance perovskite piezoelectric materials by enhancing the intrinsic lattice contribution with easy and continuous polarization rotation.

Viral pathogens appear to exert the most significant constraints on the growth and survival of crustaceans under culture conditions. The prevalence of viral pathogens White Spot Syndrome Virus (WSSV), Hepatopancreatic Parvo Virus (HPV), Monodon Baculo Virus (MBV) and Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) in Penaeus monodon post-larvae was studied. Samples collected from different hatcheries and also samples submitted by farmers from Kerala were analyzed. Out of 104 samples collected, WSSV was detected in 12.5% of the post-larvae samples. Prevalence of concurrent infections by HPV, MBV and WSSV (either dual or triple infection) was present in 60.6% of the total post-larvae tested. Out of the 51 double positives, 98% showed either HPV or IHHNV infection. HPV or IHHNV was detected in 11 post-larval samples showing triple viral infection. This is the first report of IHHNV from India. Result of this study reveals the lack of efficient screening strategies to eradicate viruses in hatchery reared post-larvae.

The Vembanad Lake located on the south-west coast of India, an ecological hotspot is the nursing ground of many economically important crustaceans. The prevalence of white spot syndrome virus (WSSV) among crustaceans from farmed, estuarine and marine environments surrounding the Vembanad Lake, India was detected using PCR. A total of 308 samples from aquaculture ponds consisting of six species of crustaceans collected from five different farms were tested for the presence of WSSV. Of these, 67% were found to carry the virus. A total of 258 samples of crustaceans from the Cochin backwater system that forms a part of the Vembanad lake viz., Metapenaeus dobsoni, Metapenaeus monoceros, Penaeus monodon and Penaeus indicus were found to contain WSSV in 62% of the samples. Fifteen species of crustaceans caught from the seas off Cochin were also screened for the presence of WSSV. Out of these, twelve species had WSSV incidence levels ranging from 6-23%. WSSV was not detected from three species of deep sea crustaceans tested. The black tiger shrimp, Penaeus monodon had the highest incidence of WSSV among the species screened in farmed, estuarine and marine environments.

Mangrovibacter sp. MFB070, a Gram-negative, facultatively anaerobic, nitrogen-fixing bacterium, was isolated from an aquaculture farm in Cochin, India. Here, we report the first draft genome sequence of a member of the genus Mangrovibacter, which may help us to elucidate the evolutionary status of this genus. The draft genome sequence of the Mangrovibacter sp. consists of 5,361,682 bp, encoding 4,971 predicted coding sequences in 57 contigs., (Copyright © 2014 Joseph et al.)

We report the 4.25-Mbp first draft sequence of Gammaproteobacteria strain MFB021, a moderate halophile isolated from petroleum-contaminated soil in Cochin, India. The genome of the strain MFB021 was sequenced to understand the mechanism of hydrocarbon degradation and the halophilicity of the bacterium., (Copyright © 2014 Joseph et al.)

In this stability-indicating, reversed-phase high-performance liquid chromatographic method for flupiritine maleate, forced degradation has been employed and the formed degradants were separated on a C18 column with a 80:20% v/v mixture of methanol-water containing 0.2% (v/v) triethylamine; the pH was adjusted to 3.1. The flow rate was 1 mLmin(-1) and the photodiode array detection wavelength was 254 nm. Forced degradation of the drug was carried out under acidic, basic, thermal, photolytic, peroxide, and neutral conditions. Chromatographic peak purity data indicated no co-eluting peaks with the main peaks. This method resulted in the detection of seven degradation products (D1-D7). Among these, three major degradation products from acidic and basic hydrolysis were identified and characterized by (1)H-NMR, (13)C-NMR, and mass spectral data. The method was validated as per International Conference on Harmonization guidelines (Q2). The linearity of the method was in the concentration range of 20-120 μgmL(-1). The relative standard deviations for intra- and interday precision were below 1.5%. The specificity of the method is suitable for the stability-indicating assay.

The effect of reduced oxygen atmosphere and sodium acetate treatment on the microbial quality of seer fish (Scomberomorus commerson) steaks was determined during chilled storage (1-2 degrees C). The O2 absorber reduced the oxygen content in the pack to less than 0.01% corresponding to 99.96% reduction within 24 h. The use of O2 absorber with sodium acetate dip treatment (2% w/v) extended the sensory shelf life up to 25 days compared to only 12 days for control air packs and 20 days for untreated samples with O2 absorber. A prominent lag phase was observed for many bacterium studied, particularly for the sodium acetate treated samples with O2 absorber. On the day of sensory rejection, both the total mesophilic and psychrotrophic counts reached 7.7-8.1 and 7.1-7.9 log cfu/g, respectively. The sodium acetate treatment and reduced O2 atmosphere affected the type of major spoilers. In air packed samples, H2S-producers predominated followed by Brochothrix thermosphacta, Pseudomonas spp., where as in the untreated samples with O2 absorber, H2S-producers predominated the microbial flora followed by Lactobacillus spp. For treated samples with O2 absorber, B. thermosphacta formed the major micro-flora followed by Lactobacillus spp. The use of O2 absorber inhibited the growth of Pseudomonas spp., and total Enterobacteriaceae., (2010 Elsevier Ltd. All rights reserved.)

Effect of packaging atmosphere (air and under different modified atmospheres (MAs), 40% CO2/60% O2, 50%/50% O2, 60% CO2/40% O2, 70% CO2/30% O2 and 40% CO2/30% O2/30% N2) on the microbial and biochemical attributes of fresh pearlspot (Etroplus suratensis Bloch) stored at 0-2 degrees C was investigated. Trimethylamine nitrogen (TMA-N) and thiobarbituric acid (TBA) values remained lower than the proposed acceptability limits throughout the storage period. Results demonstrated that storage of pearlspot under air and MA 40% CO2/30% O(2)/30% N(2) resulted in growth of Enterobacteriaceae, Aeromonas and H(2)S-producing bacteria including Shewanella putrefaciens, while all other packaging atmospheres did not allow multiplication of Enterobacteriaceae and Aeromonas within 3 weeks. Aeromonas spp. identified were Aeromonas hydrophila, Aeromonas veronii biovar sobria and A. veronii biovar veronii. Significant reduction (p<0.01) was noticed in Aeromonas population of pearlspot stored under MA 60% CO2/40% O2 and 70% CO2/30% O2. A delay of growth of Pseudomonas below 5.0log(10)cfug(-1) was observed during the 15th day of storage at 0-2 degrees C under modified atmosphere packaging (MAP) conditions. Growth of faecal streptococci was significantly inhibited in all the packaging atmospheres at 0-2 degrees C during the entire storage period. Survival of coagulase positive Staphylococci (<50cfug(-1)) in low numbers was noticed during storage in all the packaging atmospheres. Clostridium botulinum toxin was not detected. All the packaging atmospheres did not allow multiplication of sulphite-reducing clostridia at 0-2 degrees C during the entire storage period. Packaging in MA 60% CO2/40% O2 resulted in the inhibition of growth of Aeromonas and Enterobacteriaceae, and the slowest growth of psychrotrophic bacteria, H(2)S-producing bacteria, including Shewanella putrefaciens and Pseudomonas and extended microbiological shelf life to 9-10 days. This study confirms the survival of potentially pathogenic A. hydrophila, A. veronii biovar sobria and A. veronii biovar veronii capable of growth at low temperature in pearlspot stored under MA.

The occurrence of Clostridium botulinum in fresh (67) and cured fish (278) samples in retail trade in Cochin was studied. An overall prevalence of 19% (13/67) was found in fresh retail fish and types A to D were detected in the positive samples. In pelagic fish, incidence of C. botulinum was 18% (7/39) whereas in demersal fish, 21% (5/24) of the samples harboured C. botulinum. Incidence of C. botulinum in shrimp was 25% (1/4) and type D was found in the positive sample. Of 257 cured fish in retail trade tested for the presence of C. botulinum, the overall contamination level was 10% (25/257). Among the C. botulinum types A to D prevalent in fresh fish, types C and D were the predominant types found in cured products. In salt-dried shrimp, of the 21 samples analysed, 10 samples (48%) harboured C. botulinum.

Four groups of weanling male albino rats (Wistar strain) were fed isonitrogenous diet (10% protein) identical in all respects except in the nature of the protein source, for 4 weeks. Control group (group 1) had steamed mackerel meat as the protein source, whereas groups 2, 3 and 4 had mackerel fried on the 1st, 3rd and 4th days in the same coconut oil repeatedly used for frying each day. Four groups of adult male rats weighing around 130 g were fed on the same diet for 12 weeks. Weanlings fed on fish fried on the 4th day showed significantly lower feed consumption and weight gain compared to the other three groups. All the three groups of adult rats fed on fried fish compared well with control rats in weight gain and hepatosomatic index. There was a decrease in the total lipid and cholesterol content of the liver of rats fed with fried fish in comparison with the control rats. The total lipid and cholesterol in heart and serum cholesterol levels increased significantly from control rats through group 4. The C22:6/C20:5 ratio in the heart lipid showed a very high value compared to the dietary lipids. Histopathological examination showed initial stages of cell damage in the liver and kidney of rats fed with fish fried on the 4th day. In-vitro digestibility of proteins of fried fish were lower than that of steamed fish, but the difference in this respect between proteins of fish fried on different days was not significant.