Powder-blown laser-based directed energy deposition of (14M) Ni-Mn-Ga magnetic shape memory alloy

Ni-Mn-Ga-based magnetic shape memory (MSM) alloys are renowned for their large magnetic-field-induced strains, making them attractive for compact magnetically controlled actuators requiring high response frequencies and large reversible deformations. In this study, Ni-Mn-Ga alloy samples were deposited using powder-blown laser-based directed energy deposition (DED-LB), employing gas-atomised powder pre-alloyed with excess Mn. The samples were deposited following a systematic experimental design, varying the applied laser power and employing two melting strategies: unidirectional and bidirectional. The results demonstrate the feasibility of achieving high relative densities (&gt;97.5 %) in multi-layered Ni-Mn-Ga samples through DED-LB. All as-deposited samples exhibited a consistent 0.7–0.9 at% Mn loss in comparison to the powder feedstock, thus showing that the Mn overdosing requirements for DED-LB differ from those in laser powder bed fusion. Both as-deposited and heat-treated samples exhibited seven-layered modulated (14 M) martensite structures at ambient temperature. In contrast, the heat-treated samples also exhibited fully reversible martensite transformation at around 66 ºC and a Curie temperature at around 94 ºC. Distinct microstructural characteristics were observed based on the melting strategy, with bidirectional melting promoting the formation of large columnar grains with a strong &lt;100&gt; texture approximately along the build direction. This study highlights the potential of DED-LB processes in manufacturing relatively large (mm to cm scale) functional Ni-Mn-Ga actuators and contributes to the ongoing efforts in laser additive manufacturing of functional materials.</p

Detection of Colicin genes by PCR in Escherichia coli isolated from cattle in Shiraz-Iran Tahamtan 1

ABSTRACT A variety of probiotic bacteria have been tested to control animal and foodborne pathogenic bacteria in livestock. The mechanism of inhibition of pathogenic bacteria for several of those probiotic microorganisms is mediated by the production of bacteriocins. Colicins are probably the group of bacteriocins that have been most thoroughly characterized. Colicins are antimicrobial proteins produced by one strains of Escherichia coli to suppress the growth of other strains of E.coli. The present study indicated the preparation of colicin from colicinogenic bacteria. A total of three hundred rectal and rumen swabs isolated from health and diarrheic calves located in Fars province feces. One hundred and fifteen strains were confirmed as E.coli by biochemical test. Polymerase chain reaction was used to determine the following genes encoding colicins. Nearly 100% of isolates were contained at least one gene of colicin. The frequency of several classes of colicin was determined. As a result the most detected gene was Ia Ib and the least detected gene was A.N.S 4 . Colicin should be tested to control animal and foodborne pathogenic bacteria in livestock

Prevalence and molecular characterization of verotoxin-producing Escherichia coli O157:H7 in cattle and sheep in Shiraz-Iran

Shiga toxin producing Escherichia coli have been associated with HUS, HC and TTP in human. We found recto-anal mucosal sample in sheep as well in cattle is the main site for E. coli O157 localization. 1246 E. coli isolates from 872 both healthy and diarrheic animals were analyzed, by screening for the presence of Shiga toxin-producing (VT 1 and VT 2) and intimin (eae) genes used Multiplex PCR. 87(9.75%) VTEC from 52 cattle and 28(7.90%) from 28 sheep were isolated. VT2 gene was found to be more frequent than VT1 in cattle (54.02% vs 26.43%), in contrast the same genes in sheep (21.42%vs25%). There was observed significant difference in the origin of VT positive sheep in close contact with farms of cattle origin. Having cattle and sheep with each other was a possible risk factor. The animal was kept in pen was more localized than tethered. Young cattle were documented strongly significant high prevalence rate in E. coli O157:H7 than older, but no effect of age was observed on the occurrence of E. coli O157 in sheep. Both diarrheic and healthy animals were shed E. coli O157:H7 in their feces. Sheep and dairy cow were not illustrated any significance differences geographical region and seasonal variation with E. coli O157:H7 prevalence rate

Detection of Colicin genes by PCR in Escherichia coli isolated from cattle in Shiraz-Iran

A variety of probiotic bacteria have been tested to control animal and foodborne pathogenic bacteria in livestock. The mechanism of inhibition of pathogenic bacteria for several of those probiotic microorganisms is mediated by the production of bacteriocins. Colicins are probably the group of bacteriocins that have been most thoroughly characterized. Colicins are antimicrobial proteins produced by one strains of Escherichia coli to suppress the growth of other strains of E.coli. The present study indicated the preparation of colicin from colicinogenic bacteria. A total of three hundred rectal and rumen swabs isolated from health and diarrheic calves located in Fars province feces. One hundred and fifteen strains were confirmed as E.coli by biochemical test. Polymerase chain reaction was used to determine the following genes encoding colicins. Nearly 100% of isolates were contained at least one gene of colicin. The frequency of several classes of colicin was determined. As a result the most detected gene was Ia Ib and the least detected gene was A.N.S4. Colicin should be tested to control animal and foodborne pathogenic bacteria in livestock

Mixed-dimensional heterostructures of hydrophobic/hydrophilic graphene foam for tunable hydrogen evolution reaction

The synergetic effect of hydrophilic and hydrophobic carbon can be used to obtain tunable hydrogen evolution reaction (HER) at the interface. Herein, graphene oxide (GO-Hummers method) was coated on graphene foam (GF) synthesized via chemical vapor deposition to develop mixed-dimensional heterostructure for the observation of HER. The porosity of GF not only provides an optimized diffusion coefficient for better mass transport but also modified surface chemistry (GF/GO-hydrophobic/hydrophilic interface), which results in an onset potential 50 mV and overpotential of 450 mV to achieve the current density 10 mA/cm2. The surface analysis shows that inherent functional groups at the surface played a key role in tuning the activity of hybrid, providing a pathway to introduce non-corrosive electrodes for water splitting