Heat Transfer Analysis of Cryogenic EXLO Specimen Handling.

A conduction heat transfer analysis of ex situ lift-out specimen handling under cryogenic conditions (cryo-EXLO) is performed and compared with experimentally determined temperature values using a type K thermocouple. Using a finite-volume solver for heat conduction, the analysis confirms that manipulation of a specimen by a probe above a working surface cooled at liquid nitrogen (LN2) temperatures can remain below the critical vitreous temperature up to several hundreds of micrometers above the working surface, allowing for ample distance for lift out and specimen manipulation. In addition, the temperature above the cryogenic shuttle sample holder working surface remains below the vitreous temperature for several tens of minutes without adding cryogen, yielding sufficient time to complete multiple manipulations.

Variability in the acid adaptation of ten different O157:H7 and non-O157 Escherichia coli strains in orange juice and the impact on UV radiation resistance.

This study aimed to assess the impact of adaptation of ten strains of O157:H7 and non-O157 Escherichia coli to low pH (acid shock or slow acidification) and the effects of this exposure or not on the resistance of E. coli strains to UV radiation in orange juice (pH 3.5).

Conjugate Multimode Heat Transfer Analysis of Cryogenic EXLO Manipulation.

In this study, a conjugate radiation/conduction multimode heat transfer analysis of cryogenic focused ion beam (FIB) milling steps necessary for producing ex situ lift out specimens under cryogenic conditions (cryo-EXLO) is performed. Using finite volume for transient heat conduction and enclosure theory for radiation heat transfer, the analysis shows that as long as the specimen is attached or touching the FIB side wall trenches, the specimen will remain vitreous indefinitely, while actively cooled at liquid nitrogen (LN2) temperatures. To simulate the time needed to perform a transfer step to move the bulk sample containing the FIB-thinned specimen from the cryo-FIB to the cryo-EXLO cryostat, the LN2 temperature active cooling is turned off after steady-state conditions are reached and the specimen is monitored over time until the critical devitrification temperature is reached.

Hybrid materials based on chitosan functionalized with green synthesized copper nanoparticles: Physico-chemical and antimicrobial analysis.

Recently, the development of materials with antimicrobial properties has become a challenge under scrutiny. The incorporation of copper nanoparticles (NpCu) into a chitosan matrix appears to represent a viable strategy to contain the particles and prevent their oxidation. Regarding the physical properties, the nanocomposite films (CHCu) showed a decrease in the elongation at break (5 %) and an increase in the tensile strength of 10 % concerning chitosan films (control).

A Promising Use of Trimethyl Chitosan for Removing in Water Treatment Processes.

The increase in cyanobacterial blooms linked to climate change and the eutrophication of water bodies is a global concern. The harmful cyanobacterium is one of the most common bloom-forming species whose removal from fresh water and, in particular, from that used for water treatment processes, remains a crucial goal. Different biodegradable and environmentally friendly coagulants/flocculants have been assayed, with chitosan showing a very good performance.

The Eco-Physiological Role of in a Changing World.

Among the bloom-forming cyanobacteria, is one of the most harmful species [...

Mechanism of FIB-Induced Phase Transformation in Austenitic Steel.

The transformation of unstable austenite to ferrite or α′ martensite as a result of exposure to Xe+ or Ga+ ions at room temperature was studied in a 304 stainless steel casting alloy. Controlled Xe+ and Ga+ ion beam exposures of the 304 were carried out at a variety of beam/sample geometries. It was found that both Ga+ and Xe+ ion irradiation resulted in the transformation of the austenite to either ferrite or α′ martensite.

A Stochastic Characterization of Hydrogen Peroxide-Induced Regulated Cell Death in .

Regulated cell death (RCD) encompasses the activation of cellular pathways that initiate and execute a self-dismissal process. RCD occur over a range of stressors doses that overcome pro-survival cellular pathways, while higher doses cause excessive damage leading to passive accidental cell death (ACD). Hydrogen peroxide (HP) has been proposed as a potential tool to control harmful cyanobacterial blooms, given its capacity to remove cyanobacterial cells and oxidize cyanotoxins.

Cell Death in Cyanobacteria: Current Understanding and Recommendations for a Consensus on Its Nomenclature.

Cyanobacteria are globally widespread photosynthetic prokaryotes and are major contributors to global biogeochemical cycles. One of the most critical processes determining cyanobacterial eco-physiology is cellular death. Evidence supports the existence of controlled cellular demise in cyanobacteria, and various forms of cell death have been described as a response to biotic and abiotic stresses.

Fatty acid response of the invasive bivalve Limnoperna fortunei fed with Microcystis aeruginosa exposed to high temperature.

The success of Limnoperna fortunei as an invasive freshwater bivalve species is related to its physiological plasticity to endure changes in environmental conditions. The aim of this study was to investigate the physiological responses of L. fortunei after feeding on Microcystis aeruginosa grown at 26 °C (control) and 29 °C during 10 days.

[D-Leu]MC-LR Has Lower PP1 Inhibitory Capability and Greater Toxic Potency than MC-LR in Animal and Plant Tissues.

Two microcystins, MC-LR and [D-Leu]MC-LR, present in La Plata Basin blooms, are differentiated by substitution of D-Alanine for D-Leucine at position 1. Our objective was to evaluate acute toxicity of [D-Leu]MC-LR and MC-LR in mice (N:NIH Swiss) and beans (). We observed variations in [D-Leu]MC-LR lethal doses with respect to those reported for MC-LR (100 μg/kg), with an increased liver/body weight ratio and intrahepatic hemorrhages in mice exposed to 50-200 μg [D-Leu]MC-LR/kg and slight steatosis after a single 25 μg [D-Leu]MC-LR/kg i.

[D-Leu]MC-LR and MC-LR: A Small-Large Difference: Significantly Different Effects on L. (Fabaceae) Growth and Phototropic Response after Single Contact during Imbibition with Each of These Microcystin Variants.

[D-Leu]MC-LR and MC-LR, two microcystins differing in one amino acid, constitute a sanitary and environmental problem owing to their frequent and concomitant presence in water bodies of the Americas and their association with human intoxication during recreational exposure to cyanobacterial bloom. Present in reservoirs used for irrigation as well, they can generate problems in the development of crops such as , of nutritional and economic interest to the region. Although numerous works address the toxic effects of MC-LR, information on the toxicity of [D-Leu]MC-LR is limited.

Effect of temperature on microcystin-LR removal and lysis activity on Microcystis aeruginosa (cyanobacteria) by an indigenous bacterium belonging to the genus Achromobacter.

Microcystis is a frequent cyanobacterium bloom-forming with cosmopolitan distribution which can produce a hepatotoxin group called microcystins (MCs). These MCs are resistant to the traditional processes employed in the water treatment plants and they are often detected after conventional treatments. Because of this, the bio-removal studies have obtained a great interest in the last decades.

The possible role of microcystin (D-Leu MC-LR) as an antioxidant on Microcystis aeruginosa (Cyanophyceae). In vitro and in vivo evidence.

Microcystins constitute a serious threat to the quality of drinking water worldwide. However, the eco-physiological role of them is not completely known and it is suggested that toxins can play a role in the antioxidant protection. The objective of this study was to evaluate the microcystin antioxidant capacity in vitro by Electronic Paramagnetic Resonance, highly specific for the different reactive oxygen species and in vivo by 7 days exposure of Microcystis aeruginosa to high (29 °C) temperature in addition to a 26 °C control condition.

Low arsenic concentrations impair memory in rat offpring exposed during pregnancy and lactation: Role of α7 nicotinic receptor, glutamate and oxidative stress.

Inorganic arsenic (iAs) is an important natural pollutant. Millions of individuals worldwide drink water with high levels of iAs. Arsenic exposure has been associated to cognitive deficits.

Physiological responses and toxin production of Microcystis aeruginosa in short-term exposure to solar UV radiation.

The aim of this study was to evaluate the effects of short-term (hours) exposure to solar UV radiation (UVR, 280-400 nm) on the physiology of Microcystis aeruginosa. Three solar radiation treatments were implemented: (i) PAR (PAR, 400-700 nm), (ii) TUVA (PAR + UVAR, 315-700 nm) and (iii) TUVR (PAR + UVAR + UVBR, 280-700 nm). Differential responses of antioxidant enzymes and the reactive oxygen species (ROS) production to UVR were observed.

Assembly of chitosan support matrix with gallic acid-functionalized nanoparticles.

The incorporation of gallic acid (GA) in a direct way or into nanoparticles included in chitosan edible films appears as a suitable approach to increase its preservation upon adverse conditions. The addition of nanoparticles to chitosan-based matrices resulted in improvements in their solubility, swelling, and mechanical properties. It is worth noting that by means of the nanoencapsulation, the release process can be modulated in relation to the delivery of GA included directly in the matrix, releasing the agent at a lower rate for a longer time.

Growth, toxin production, active oxygen species and catalase activity of Microcystis aeruginosa (Cyanophyceae) exposed to temperature stress.

Microcystis are known for their potential ability to synthesize toxins, mainly microcystins (MCs). In order to evaluate the effects of temperature on chlorophyll a (Chl a), growth, physiological responses and toxin production of a native Microcystis aeruginosa, we exposed the cells to low (23°C) and high (29°C) temperature in addition to a 26°C control treatment. Exponential growth rate was significantly higher at 29°C compared to 23°C and control, reaching 0.

Antifungal effect of kefir fermented milk and shelf life improvement of corn arepas.

Fungal contamination negatively affects the production of cereal foods such as arepa loaf, an ancient corn bread consumed daily in several countries of Latin-America. Chemical preservatives such as potassium sorbate are applied in order to improve the arepa's shelf life and to reduce the health risks. The use of natural preservatives such as natural fermented products in food commodities is a common demand among the consumers.

Assessment of carboxyhemoglobin, hydrogen cyanide and methemoglobin in fire victims: a novel approach.

To establish the cause of death, carboxyhemoglobin (COHb), total hemoglobin (tHb), methemoglobin (MetHb), and hydrogen cyanide (HCN) were quantified in the blood of fire victims. We analyzed 32 out of 33 blood samples from forensic autopsy cases in a disastrous polyurethane mattress fire, which caused the deaths of 33 inmates at a prison in Argentina in 2006. The cadaveric blood samples were collected by femoral vein puncture.

Changes induced by UV radiation in the presence of sodium benzoate in films formulated with polyvinyl alcohol and carboxymethyl cellulose.

This work was focused on: i) developing single and blend films based on carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVOH) studying their properties, ii) analyzing the interactions between CMC and PVOH and their modifications UV-induced in the presence of sodium benzoate (SB), and iii) evaluating the antimicrobial capacity of blend films containing SB with and without UV treatment. Once the blend films with SB were exposed to UV radiation, they exhibited lower moisture content as well as a greater elongation at break and rougher surfaces compared to those without treatment. Considering oxygen barrier properties, the low values obtained would allow their application as packaging with selective oxygen permeability.

Theory and New Applications of Ex Situ Lift Out.

The ex situ lift out (EXLO) adhesion forces are reviewed and new applications of EXLO for focused ion beam (FIB)-prepared specimens are described. EXLO is used to manipulate electron transparent specimens on microelectromechanical systems carrier devices designed for in situ electron microscope analysis. A new patented grid design without a support film is described for EXLO.

Hepatic and intestine alterations in mice after prolonged exposure to low oral doses of Microcystin-LR.

Oral intake of Microcystin-LR (MC-LR) is the principal route of exposure to this toxin, with prolonged exposure leading to liver damage of unspecific symptomatology. The aim of the present paper was therefore to investigate the liver and intestine damage generated by prolonged oral exposure to low MC-LR doses (50 and 100 μg MC-LR/kg body weight, administrated every 48 h during a month) in a murine model. We found alterations in TBARS, SOD activity and glutathione content in liver and intestine of mice exposed to both doses of MC-LR.