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Interactions within bacterial communities are frequently mediated by the production of antimicrobial agents. Despite the increasing interest in research of new antimicrobials, studies describing antagonistic interactions among cold-adapted microorganisms are still rare. Our study assessed the antimicrobial interactions of 36 Antarctic Pseudomonas spp. and described the genetic background of these interactions in selected strains. The overall bacteriocinogeny was greater compared to mesophilic Pseudomonas non-aeruginosa species. R-type tailocins were detected on transmission electron micrographs in 16 strains (44.4%); phylogenetic analysis of the corresponding gene clusters revealed that the P. prosekii CCM 8878 tailocin was related to the Rp3 group, whereas the tailocin in Pseudomonas sp. CCM 8880 to the Rp4 group. Soluble antimicrobials were produced by eight strains (22.-2%); gene mining found pyocin L homologues in the genomes of P. prosekii CCM 8881 and CCM 8879 and pyocin S9-like homologues in P. prosekii CCM 8881 and Pseudomonas sp. CCM 8880. Analysis of secretomes confirmed the production of all S- and L-type pyocin genes. Our results suggest that bacteriocin-based inhibition plays an important role in interactions among Antarctic soil bacteria, and these native, cold-adapted microorganisms could be a promising source of new antimicrobials.

The present study pertains to the exploitation of biowaste generated through Banana (Musa acuminate L.) peels for the synthesis of green silver nanoparticles (AgNPs) and their bioactivity was evaluated for managing the dengue vector, Aedes aegypti. UV-VIS specrtophotometery was used for confirming AgNPs synthesis and a peak was observed at 426 nm. Characterization of AgNPs was done using Scanning electron microscopy which depicted spherical shape of AgNPs while Transmission electron micrographs revealed their size to be ranging from 20 to 50 nm. AgNPs bioactivity was studied against III instar larvae following 24, 48 and 72 h exposure and values of LC50 and LC90 were analyzed using probit analysis. LC50 values ranged from 10.69 to 25.15 ppm with AgNPs at various time exposures. Antioxidant potential of these AgNPs was also evaluated to supplement these findings. This study highlights the potential of biowastes as a potent larvicide against Aedes aegypti.

ZnS nanoparticles (NPs) were synthesized using a simple, green, and reproducible hydrothermal method. Transmission electron micrographs show polyhedral NPs having an average diameter of 21 nm; whereas the X-ray diffraction analysis is consistent with the exclusive presence of cubic ZnS; however no oxide could be detected. A comprehensive characterization of the NPs' surface was accomplished through X-ray photoelectron spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), Raman, and thermogravimetric analysis-differential scanning calorimetry, showing a fairly pure ZnS composition and a remarkable amount of adsorbed water molecules. The interaction capabilities of the surface were probed in situ by DRIFT using small molecules (CO, CO2, methanol, pyridine) as molecular probes. The same interactions were also theoretically studied with density functional calculations using a slab model based on the sphalerite ZnS (110) surface. By comparing theoretical and experimental vibrational shifts, insights on the nature of the interaction between molecular probes and surfaces were obtained. Water was found to alter both the structure as well as the reactivity of the surface, mediating the interaction of methanol with the surface, and allowing the conversion of CO2 into surface carbonates. Pyridine was instead evidenced to be able to replace water molecules because of its high adsorption energy (1 eV) which is in tune with the known pyridine-detection capabilities of ZnS. No-SH moieties or Lewis acid behavior of the exposed S atoms were observed.

This work investigates defect formation and evolution associated with the deposition of GaP layers on precisely oriented Si(0 0 1) substrates. The GaP layers were grown with thicknesses ranging from ∼37 nm to ∼2 µm at a growth rate of 0.52 μm/hr using molecular beam epitaxy (MBE). The crystallinity of thin (37-nm) MBE-grown GaP layers was also compared with thin GaP layers grown by migration-enhanced epitaxy (MEE). The MBE growth procedure was shown to postpone relaxation of the epitaxial GaP layers up to a thickness of ∼250 nm. Detailed analysis of high-resolution X-ray diffraction patterns and comparison with cross-sectional transmission electron micrographs clarified the defect formation mechanism. Thin GaP layers showed very low defect densities except for anti-phase boundaries, whereas substantial threading defects predominated in the thicker, noticeably relaxed structures.

Near-shore marine sediments deposited during the Paleocene-Eocene Thermal Maximum at Wilson Lake, NJ, contain abundant conventional and giant magnetofossils. We find that giant, needle-shaped magnetofossils from Wilson Lake produce distinct magnetic signatures in low-noise, high-resolution first-order reversal curve (FORC) measurements. These magnetic measurements on bulk sediment samples identify the presence of giant, needle-shaped magnetofossils. Our results are supported by micromagnetic simulations of giant needle morphologies measured from transmission electron micrographs of magnetic extracts from Wilson Lake sediments. These simulations underscore the single-domain characteristics and the large magnetic coercivity associated with the extreme crystal elongation of giant needles. Giant magnetofossils have so far only been identified in sediments deposited during global hyperthermal events and therefore may serve as magnetic biomarkers of environmental disturbances. Our results show that FORC measurements are a nondestructive method for identifying giant magnetofossil assemblages in bulk sediments, which will help test their ecology and significance with respect to environmental change.

The order-disorder transition in Ni-Al alloys under irradiation represents an interplay between various reordering processes and disordering due to thermal spikes generated by incident high energy particles. Typically, ordering is enabled by diffusion of thermally generated vacancies, and can only take place at temperatures where they are mobile and in sufficiently high concentration. Here, in situ transmission electron micrographs reveal that the presence of He---usually considered to be a deleterious immiscible atom in this material---promotes reordering in ${\mathrm{Ni}}_{3}\mathrm{Al}$ at temperatures where vacancies are not effective ordering agents. A rate-theory model is presented, that quantitatively explains this behavior, based on parameters extracted from atomistic simulations. These calculations show that the ${\mathrm{V}}_{2}\mathrm{He}$ complex is an effective agent through its high stability and mobility. It is surmised that immiscible atoms may stabilize reordering agents in other materials undergoing driven processes, and preserve ordered phases at temperature where the driven processes would otherwise lead to disorder.

Chinese rice wine, a traditional wine widely consumed in China, is typically sterilized in light of its sublethal alcohol content and nutritional richness. Nevertheless, several foodborne pathogens have been detected in final products, of which Bacillus cereus is one of the most heat-resistant. To study the effects of the wine matrix on bacterial inactivation, simulated media were established based on the main characteristics of the wine, including glucose content (23.48 ± 0.86 g/L), alcohol content (17.0 ± 0.5%), pH (4.14 ± 0.06), and protein content. In Chinese rice wine, log counts declined to 5.79 after 1 min heat treatment at 60.0 °C, 4.99 at 70.0 °C, and 4.37 at 80.0 °C. The loss of viability was smaller in simulated media with protein and glucose than in sterile saline, implying that glucose and especially protein were protective. The inactivation kinetics of B. cereus vegetative cells were then assessed in these media, and modeled. Remarkably, thermal survival curves in Chinese rice wine and simulated media were linear and well-modeled by first-order kinetics with R2 values 0.9501–0.9992. The data demonstrated that media with acidic pH were the most adverse environment against B. cereus, with D-value 0.61 ± 0.02 min at 60.0 °C. Similar values were obtained in media with 23.48 g/L glucose at 80.0 °C. Transmission electron micrographs showed heat-induced injuries in B. cereus through “coagulation” of the cytoplasmic content in all the media. Furthermore, modifications on the cell wall in acidic pH and alcohol media, leakage of cellular content observed in Chinese rice wine and glucose media. Conclusively, the results might help optimize the sterilization parameters to ensure the safety and quality of Chinese rice wine.

Bacteriophages that infect the foodborne pathogen Listeria monocytogenes were previously isolated from New York dairy farms. The complete genome sequences for three of these Listeria phages, with genome sizes of 64.6 to 65.7 kb, are presented here. Listeria phages LP-010, LP-013, and LP-031-2 are siphoviruses that belong to the genus Homburgvirus .

Reduction-responsive vesicle was prepared by salt-bridging N-[3-(dimethylamino)propyl]-octadecanamide (DMAPODA, a cationic amphiphile) using 3,3′-dithiodipropionic acid (DTPA, a disulfide diacid compound). According to the transmission electron micrograph and the fluorescence quenching degree (53.2%), it could be said that vesicles were formed when the DMAPODA to DTPA molar ratio was 2:2. The DMAPODA/DTPA associate was considered to be a building block for vesicle formation because DTPA could electrostatically associate with DMAPODA and help the cationic amphiphile assemble into the vesicle. On a differential scanning calorimetric thermogram, the DMAPODA/DTPA vesicle showed two endothermic peaks at 50.6°C and 63.2°C. The peak found at the lower temperature was possibly due to the solid gel-to-liquid crystal phase transition of the vesicular membrane and the peak found at the higher temperature was considered to be due to the melting of DMAPODA, indicating that unassociated DMAPODA coexisted with D...

Custom built in-situ ultrasonic aging equipment was used to investigate the precipitation hardening response in a commercial WE43 alloy at 210°C. Three power levels (100, 300, 400 W) with time intervals of 15, 30, and 60 s between sonication were used to measure the change in hardness. Aging response was 24 times faster, decreasing the time to achieve peak hardness from 48 hrs during conventional aging to 2 hrs under the influence of ultrasonic waves. While higher power increased the peak hardness, shortening the interval time from 30 to 15 s did not have any influence. Transmission electron micrographs revealed well-developed β1 variants in as little as 15 minutes for ultrasonically aged samples, which was the reason for enhanced age hardening response.

Summary Nutrients and temperature are the major elements in maintaining stable endosymbiotic relationships. The mechanisms and response of cultured Symbiodinium cells in the absence of nitrogen, and at various temperatures are still unclear. The present study investigated the influence of different temperatures and nitrogen-deprivation on free-living Symbiodinium cultures. The physiological responses of free-living Symbiodinium cells cultured at different temperatures during nitrogen deprivation under a 12:12 h light:dark were measured. Symbiodinium cell growth was significantly lower in response to lower temperatures. Transmission electron micrographs (TEMs) revealed the formation of lipid droplets induced by nitrogen deprivation under different temperatures. The results of this study will increase our understanding of adaptive responses occurring in Symbiodinium under environmental stress.

Ferrite nanoparticles (NPs) with composition $$\hbox {MFe}_{2}\hbox {O}_{4}$$ (M = Mg/Co) were synthesized by a facile combustion method. NPs were characterized employing various physico-chemical techniques. X-ray diffraction patterns confirmed the phase purity, transmission electron micrographs indicated that NPs are spherical and average diameter of maximum fraction of NPs was in the range of 20–30 nm. Magnetic studies revealed that the saturation magnetization values for $$\hbox {MgFe}_{2}\hbox {O}_{4}$$ and $$\hbox {CoFe}_{2}\hbox {O}_{4}$$ NPs were 13.17 and 41.12 emu $$\hbox {g}^{-1}$$ , respectively. The Brunauer–Emmett–Teller surface area of $$\hbox {CoFe}_{2}\hbox {O}_{4}$$ and $$\hbox {MgFe}_{2}\hbox {O}_{4}$$ NPs was 22.98 and 34.39 $$\hbox {m}^{2}$$ $$\hbox {g}^{-1}$$ , respectively. Synthesized ferrite NPs and activated charcoal were comparatively analysed as adsorbents for removal of Pb(II) ions. The factors influencing uptake behaviour of Pb(II) ions viz. adsorbent dose, pH, concentration, temperature and contact time were quantified. The adsorption data showed good correlation with Langmuir and Freundlich models as compared to Dubinin–Radushkevich model. The maximum adsorption capacity displayed a two-fold increase for NPs as compared to activated charcoal. The easy magnetic separation of ferrite NPs from the solution and their regeneration with 0.1 N NaOH for reuse without any loss make them potential adsorbents. The trend in ascending order for the elimination of Pb(II) ions from the solution was activated charcoal $$