Autoclaved Samples Research Articles

Biosynthesis and Functionalization of Bacterial Cellulose Membranes with Cerium Nitrate and Silver Nanoparticles

This work aimed to synthesize bacterial cellulose (BC) membranes functionalized with Ce(NO3)3 and silver nanoparticles (AgNPs) heat-treated in oven and autoclave. The AgNPs were characterized by TEM and the membranes were characterized by their rehydration capacity, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy with Dispersive Energy Spectroscopy (SEM/EDS), Wide-angle X-ray Diffractometry (XRD), Atomic Absorption Spectroscopy (AAS), antimicrobial activity and cytotoxicity. The BC membranes were white to light yellow or brown indicating functionalization with AgNps with 20 nm. XRD detected a decrease in the degree of crystallinity in functionalized membranes. The autoclaved samples exhibited the largest porosity and good rehydration capacity. AAS showed Ag presence in all samples. The best antibacterial activity was achieved for the membrane’s oven treated with 40 ppm of AgNPs. Among the functionalized membranes, the most recommended to be used as burn dressing is the Ag40A and Ag20CN1.1A since they showed good porosity, good antimicrobial activity, and better suitable cell viability.

Effect of replacing maize and starch with Shoti meal (Curcuma zedoaria) in broiler

The effects of raw and autoclaved Shoti (Curcuma zedoaria) meal on the growth and N utilization of growing broilers were determined. Shoti from Bangladesh Agricultural University campus was collected and sorted on the basis of white color of the rhizome. Then they were chopped into pieces, sun dried and pulverized in a flour mill. Aliquot samples were autoclaved at 1200C under 15 lb of pressure per square inch for 30 min. Autoclaved samples were stored in tightly lid contained for future use. 3 One hundred -day-old Cobb 500 broiler chicks were reared on the floor and a total of 24 growing broilers, 4 birds in each group were weighed on d 15 Two broilers were placed in each cage. There were a total of four experimental and two control (positive and negative Non-protein control) diets. Diets were fed ad libitum from day 15 to 33days. Body weight, feed intake, feed refusal and fecal weights were recorded every day. Cumulative feed efficiency per bird was calculated as the ratio of weight gained to feed consumed. Dry matter of excreta was determined from the last 10 d of feeding trial by drying aliquots of every day’s droppings by drying for 6 h at 1050C. On d 19, birds were bled to death. Immediately after slaughter, the carcasses were examined systematically. The chemical composition of Shoti meal showed that it is low in protein, fat and trace minerals and therefore mainly a source of energy. The bulk of the tuber (75 percent) consists of carbohydrates, made up of 10.6% fiber, and 64.9% nitrogen free extracts (NFE). A peculiarity of Curcuma rhizome meal contains high level of ash (9.9%) on DM basis. The results showed that at day 33, the weight of the broiler chicken fed shoti 100g, 200g, 300 g and 200g (autoclaved shoti meal)/ Kg diet was significantly different from the weight of the chicken fed on a maize-soybean diet. The birds given shoti meal consumed less feed than those provided with a maize diet. Feed efficiency or weight gain to feed ration over 19-d period was the poorest when fed 300 g Shoti/ Kg diet. Intake picked up when the shoti meal was incorporated after having been autoclaved and there was slight improvement in body weight gain as compared to that of other Shoti fed group. However, feed efficiency and body weight gain as % of initial weight remained significantly lower than the maize-soybean control. The inclusion of Shoti meal generally had an adverse effect on the apparent dry matter digestibility compared with the control diets. The group fed autoclaved shoti meal had a similar effect and the true N digestibility was the lowest when compared to those of control fed on maize-soybean meal. Thus, physical treatment like using autoclave, caused further reduction of digestibility of its N. Lipid digestibility was reduced by ingestion of shoti meal. Since the diets were isocaloric, after correction for the apparent endogenous lipid losses, which were obtained from the results of non-protein control feeding, the net faecal losses was around 66.2% of the ingested lipid against control diet fed birds.
 Bang. J. Anim. Sci. 2018. 47 (1): 40-46

XRD analysis of phase development and peak broadening during the production of AAC

AbstractThe production process of autoclaved aerated concrete (AAC) is driven by the transformation of mineral phases. During green cake step, strength is developed by the formation of hydrate phases such as ettringite and in larger quantity portlandite. In respective XRD plots, portlandite often shows anisotropic peak broadening due to anisotropic domain morphology. A new implementation in Rietveld refinement allows to refine the peak broadening calculating anisotropic domain sizes. An appropriate model is used to approximate the domains of portlandite. In this way, it is possible to track the mechanism of portlandite growth during hydration and the quantification of phase development during the green cake hydration is performed more precisely. In autoclaved samples, the main phase is tobermorite, which shows anisotropic peak broadening as well. The application of the described approach in a similar way to portlandite enables an advanced refinement. To approximate the domains of tobermorite a triaxial cylinder model is used, so that tobermorite is characterized more accurately. In addition, this method allows to investigate the influence of variations in the chemical composition of raw materials on domain morphology of tobermorite, as exchanged ions like Al3+ make a significant impact. Consequently, a new possibility to analyze the link between mechanical and thermal properties and phase characteristics is given.

Usability of chemical additives to accelerate initial curing time of AAC

AbstractAutoclaved aerated concrete (AAC) products have been promising materials for the construction sector. For this reason, fast production techniques are becoming more important in this area. In the present study, effects of chemical accelerators on the initial curing time of AAC blocks have been studied. Two different organic additives (Ad1 and Ad2), which are commercial chemical agents used as setting accelerators in cement sector, were studied to investigate effects of curing times of G2/350 receipt. Ad1 and Ad2 were added into the raw materials mix of G2/350 recipe in proportion of 0.3, 0.6, and 0.9% of cement amount in raw materials mix during mixing process. Curing times of expended mud (cake) samples were measured by the hardening apparatus. On the other hand, mechanical, physical, and microstructural analyses of autoclaved samples were investigated. According to the results, it is determined that Ad1 and Ad2 can be used as a curing accelerator in production of AAC blocks. In addition to that Ad1 (in the amount of 0.3%) is the most suitable chemical agent to shorten initial curing time of R1 recipe of AAC.

Trichoderma polysporum selectively inhibits white-nose syndrome fungal pathogen Pseudogymnoascus destructans amidst soil microbes

BackgroundPseudogymnoascus destructans (Pd), the causative fungal agent of white-nose syndrome (WNS), has led to the deaths of millions of hibernating bats in the United States of America (USA) and Canada. Efficient strategies are needed to decontaminate Pd from the bat hibernacula to interrupt the disease transmission cycle without affecting the native microbes. Previously, we discovered a novel Trichoderma polysporum (Tp) strain (WPM 39143), which inhibited the growth of Pd in autoclaved soil samples. In the present investigation, we used culture-based approaches to determine Tp-induced killing of native and enriched Pd in the natural soil of two bat hibernacula. We also assessed the impact of Tp treatment on native microbial communities by metagenomics.ResultsOur results demonstrated that Tp at the concentration of 105 conidia/g soil caused 100% killing of native Pd in culture within 5 weeks of incubation. A 10-fold higher concentration of Tp (106 conidia/g soil) killed an enriched Pd population (105 conidia/g soil). The 12,507 fungal operational taxonomic units (OTUs, dominated by Ascomycota and Basidiomycota) and 27,427 bacterial OTUs (dominated by Acidobacteria and Proteobacteria) comprised the native soil microbes of the two bat hibernacula. No significant differences in fungal and bacterial relative abundances were observed between untreated and Tp-treated soil (105Tp conidia/g soil, p ≤ 0.05).ConclusionsOur results suggest that Tp-induced killing of Pd is highly specific, with minimal to no impact on the indigenous microbes present in the soil samples. These findings provide the scientific rationale for the field trials of Tp in the WNS-affected hibernacula for the effective decontamination of Pd and the control of WNS.

Analysis of surfacing materials from cast carbide alloys using inductively coupled plasma atomic emission spectrometry (ICP-AES)

A technique for analysis of surfacing materials (cast cobalt-based carbide alloys) using by ICP-AES in combination with microwave autoclave sample preparation is developed. Composition of the acid mixture, temperature and time parameters of the sample preparation under microwave heating in an autoclave are specified, thus ensuring complete quantitative transfer of the sample into a convenient analytical form without losses of volatile components for the subsequent ICP-AES analysis. Analytic lines of the elements free from spectral interference were chosen to determine all the rated components in the casting materials from cast carbide alloys. Study of surfacing materials was carried out using alloys Pr-B3K-PrH-U10Kh63B5, Pr-B3K-P-PrN-U20Kh57B10 and TsN-2-E-190K62X29B5C2, containing the alloying elements (% wt.): Co (up to 65); Cr (28.0 – 32.0); W (4.0 – 11.0); Si (1.0 to 3.0); C (1.0 – 2.0); Ni (0.1 – 2.0); Mn (0.3 – 0.6) and Fe (up to 2.0). The correctness of determining rated element was confirmed in analysis of standard samples using sample weight variation. The developed technique was tested on industrial prototypes of surfacing materials made of cobalt-based cast carbide alloys of tested grades. The method is rapid (11-fold reduction in the time of analysis) and reagent-saving (by 12.5 times) procedure compared to single-element methods by 11 times and reduction of the volume of applied reagents. Combination of the multielement ICP-AES method with microwave sample preparation provides an increase in the accuracy of Si, Cr, Mn, Fe, Ni, and W determination in surfacing materials of cast carbide alloys within a range of rated concentrations.

Evaluation and modification of lanthanum-based flocculation for isolation of bacteria from water samples

Molecular detection of pathogenic microorganisms in drinking and natural water is often challenged by low concentrations of the sought-after agents. Convenient methods to concentrate bacteria from water samples ranging from 1-10 L are highly warranted. Here we account for the evaluation of a lanthanum-based flocculation method to concentrate bacteria from water samples, applying four different bacterial species in tap water as well as river water. Our results show that the success of lanthanum-based flocculation is determined by both the bacterial species and the nature of the water sample. For tap water, satisfying flocculation efficiencies (above 60 %) were only reached for autoclaved water samples. However, the performance of the lanthanum-based flocculation method for non-autoclaved water was markedly improved by the addition of 20 mM bicarbonate to increase alkalinity. Our modified flocculation protocol may be applied as an alternative concentration method for bacteria in water samples of one liter or more.

Optimization of hyaluronic acid production and its cytotoxicity and degradability characteristics

In the present study, culture conditions of Streptococcus equi was optimized through Box–Behnken experimental design for hyaluronic acid production. About 0.87 gL−1 of hyaluronic acid was produced under the determined conditions and optimal conditions were found as 38.42 °C, 24 hr and 250 rpm. The validity and practicability of this statistical optimization strategy were confirmed relation between predicted and experimental values. The hyaluronic acid obtained under optimal conditions was characterized. The effects of different conditions such as ultraviolet light, temperature and enzymatic degradation on hyaluronic acid produced under optimal conditions were determined. 118 °C for 32 min of autoclaved HA sample included 63.09 µg mL−1 of d-glucuronic acid, which is about two-fold of enzymatic effect. Cytotoxicity of hyaluronic acid on human dermal cells (HUVEC, HaCaT), L929 and THP-1 cells was studied. In vitro effect on pro or anti-inflammatory cytokine release of THP-1 cells was determined. Although it varies depending on the concentration, cytotoxicity of hyaluronic acid is between 5 and 30%. However, it varies depending on the concentration of hyaluronic acid, TNF-α release was not much increased compared to control study. Consequently, purification procedure is necessary to develop and it is worth developing the bacterial hyaluronic acid.

Effect of Dephytinization by Fermentation and Hydrothermal Autoclaving Treatments on the Antioxidant Activity, Dietary Fiber, and Phenolic Content of Oat Bran.

Fermentation and hydrothermal methods were tested to reduce the phytic acid (PA) content of oat bran, and the effects of these methods on the dietary fiber (DF) and total phenolic (TP) contents as well as the antioxidant activity (AA) were also investigated. Fermentation with 6% yeast and for 6 h resulted in 88.2% reduction in PA content, while it only resulted in 32.5% reduction in the sample incubated for 6 h without yeast addition. The PA loss in autoclaved oat bran sample (1.5 h, pH 4.0) was 95.2% while it was 41.8% at most in the sample autoclaved without pH adjustment. In both methods, soluble, insoluble, and total DF contents of samples were remarkably higher than the control samples. Also for TP in the oat bran samples, both processes led to 17% and 39% increases, respectively, while AA values were 8% and 15%, respectively. Among all samples, the autoclaving process resulted in the lowest PA and the greatest amount of bioactive compounds.

Permeability of carbon fibre PEEK composites for cryogenic storage tanks of future space launchers

This work presents an experimental investigation into the permeability of carbon fibre (CF) polyetheretherketone (PEEK) for cryogenic storage tanks for space applications. The effects of cryogenic cycling, manufacturing method, PEEK matrix type, fibre type, cryogenic temperatures, pressure, and thickness on the permeability of CF-PEEK laminates are investigated. Laminates are manufactured using autoclave, press and in-situ laser assisted automated tape placement (ATP) consolidation. Optical microscopy is used to characterise the microstructure of test samples. The results show that, for undamaged autoclaved CF-PEEK samples, the permeability remains essentially constant for the ranges of pressures and thicknesses tested. Samples manufactured using the ATP process and samples which were damaged by cryogenic cycling, had a higher leak rate than autoclaved and pressed samples. For cryogenically cycled samples, the leak rate was shown to be dependent on the damage state of the microstructure.

Dissolved organic nitrogen recalcitrance and bioavailable nitrogen quantification for effluents from advanced nitrogen removal wastewater treatment facilities

The objective of this study was to determine the composition of nitrogen (N) in the effluents of advanced N removal (ANR) wastewater treatment plants (WWTPs). This study also tested two different experimental protocols for determining dissolved N recalcitrance. An analysis of 15 effluent samples from five WWTPs, showed effluent concentrations and especially effluent composition varied greatly from one system to the other, with total nitrogen (TN) ranging between 1.05 and 8.10 mg L−1. Nitrate (NO3−) accounted for between 38 ± 32% of TN, and ammonium accounted for a further 29 ± 28%. All of these samples were dominated by dissolved inorganic nitrogen (DIN; NO3− + NH4+), and uptake experiments indicated the DIN fraction was as expected highly bioavailable. Dissolved organic N (DON) accounted for 20 ± 11% for the total dissolved N in these effluents, and uptake experiments indicated the bioavailability of this fraction varied between 27 ± 26% depending on the WWTP assessed. These results indicate near complete DIN removal should be the primary goal of ANR treatment systems. The comparison of bioavailable nitrogen (BAN) quantification protocols showed that the dissolved nitrogen uptake bioassay approach was clearly a more reliable way to determine BAN concentrations compared to the conventional cell yield protocol. Moreover, because the nitrogen uptake experiment was much more sensitive, this protocol made it easier to detect extrinsic factors (such as biological contamination or toxicity) that could affect the accuracy of these bioassays. Based on these results, we recommend the nitrogen uptake bioassay using filtered and autoclaved samples to quantify BAN concentrations. However, for effluent samples indicating toxicity, algal bioassays will not accurately quantify BAN.

Kinetics of Duplex Oxide Growth on 9Cr Steels Exposed in CO2: Application of Dimensional Metrology

Investigations into potentially extending the lives of UK advanced gas-cooled reactors have highlighted the need for improved understanding of the long-term oxidation and carburisation of 9Cr ferritic steels. These steels were used in evaporators and primary superheaters and as these are to be used beyond their original design lives, it is necessary to ensure that these degradation routes remain within acceptable levels. A dimensional metrology technique has been applied to archived autoclave samples to measure such damage. These samples had previously been exposed to a range of temperatures, pressures and gas chemistries representative of those experienced by 9Cr steels in CO2-rich AGR gases. Earlier sample assessments had focused on weight change measurements, but the dimensional technique enables measurement of duplex oxide thicknesses around samples and the extraction of related data from longer exposure times. These data also support estimation of the extent of both carbon and oxygen uptake.

Proximal sensing of soil biological activity for precision agriculture

There is growing interest in monitoring soil biological health to complement the traditional evaluation of soil physical and chemical characteristics in agricultural fields. Activity of soil microorganisms mediates many essential soil processes that affect fertility, and, therefore, essential to the successful adoption of precision agriculture. However, there are technical limitations to cost-effective monitoring of spatial and temporal dynamics of soil biological activity across agricultural landscapes. This paper summarizes three consecutive studies on in situ measurement of soil biological activity. The first study reveals spatial heterogeneity of microbial population growth in three agricultural fields using bio-films. In the second study, microbiological activity was analyzed using a substrate-induced respiration technique. This technique was evaluated through a series of soil toxicity experiments that involved a comparison of fresh and autoclaved soil samples. Finally, the aim of the third study was to develop a portable instrumented system to evaluate carbon dioxide concentrations in soil by extracting air stored within the soil pores. This instrument was tested under various conditions to quantify the effects of soil moisture, compaction and presence of glucose (artificially increased microbial respiration). Optimization of the discussed techniques will allow for detailed mapping of these indices of soil biological health and their interactions with the physical and chemical environment at any specific point in time.

Myxomycete Assemblages Recovered from Experimental Grass and Forb Microhabitats Placed Out and Then Recollected in the Tallgrass Prairie Preserve, OK

Abstract Results obtained in studies of grassland myxomycetes (plasmodial slime molds or myxogastrids), based on the species appearing in moist-chamber cultures, have indicated that forb microhabitats yield considerably more collections than grass microhabitats. We experimentally evaluated this pattern at the Tall Grass Prairie Preserve in Oklahoma by using litterbags prepared with autoclaved samples of grasses and forbs. We obtained a total of 162 collections representing 20 species; Perichaena pedata and Diderma effusum were the dominant species present. Total number of collections, species richness, and species diversity were significantly higher for forb microhabitats when compared to grass microhabitats. These results corroborate previous reports and demonstrate the utility of using litterbags as an experimental approach to assess myxomycete diversity and to confirm or refute observations from previous ecological studies.

Enhancement of Biodegradation of Palm Oil Mill Effluents by local Isolated Fungi

This study was designed to investigate the fungi associated with palm oil mill effluent (POME) in Gulur village of Tumkur. Biodegradation of palm oil mill effluents was conducted to measure the discarded POME based on physicochemical quality. The fungi that were isolated are Aspergillusniger, A. flavus, A. fumigatus, A. ochraceus, Rhizopussp, Peniciliumsp and Trichodermavirde. The autoclaved and unautoclaved raw POME samples were incubated for 7 days and the activities of the fungi were observed each for 12 hours. The supernatants of the digested POME were investigated for the removal of chemical oxygen demand (COD), color (ADMI), and biochemical oxygen demand (BOD) at the end of each digestion cycle. The results showed that the unautoclaved raw POME sample degraded better than the inoculated POME sample and this suggests that the microorganisms that are indigenous in the POME are more effective than the introduced micro-organisms. This result, however, indicates the prospect of isolating indigenous microorganisms in the POME for effective biodegradation of POME. Moreover, the effective treatment of POME yields useful products such as reduction of BOD, COD, and color.

Dissipation of pterosin B in acid soils – Tracking the fate of the bracken fern carcinogen ptaquiloside

Bracken ferns (Pteridium spp.) are well-known for their carcinogenic properties, which are ascribed to the content of ptaquiloside and ptaquiloside-like substances. Ptaquiloside leach from the ferns and may cause contamination of drinking water. Pterosin B is formed by hydrolysis of ptaquiloside. In soil, Pterosin B is adsorbed more strongly and it is expected to have a slower turnover than ptaquiloside. We thus hypothesized that pterosin B may serve as an indicator for any past presence of ptaquiloside. Pterosin B degradation was studied in acid forest soils from bracken-covered and bracken-free areas. Soil samples were incubated with pterosin B at 3 and 8 μg g−1 for 10 days, whereas sterile (autoclaved) samples were incubated for 23 days. Pterosin B showed unexpected fast degradation in soils with full degradation in topsoils in 2–5 days. Pterosin B dissipation followed the sum of two-first order reactions. The initial fast reaction with half-lives of 0.7–3.5 h contributed 11–59% of the total pterosin B degradation, while the slow reaction was 20–100 times slower than the fast reaction. Total dissipation half-lives were shorter for loamy sand (4 h) than for sandy loam soils (28 h). No degradation of pterosin B took place under sterile conditions assuming observed dissipation during the first 3 h could be attributed to irreversible sorption. Our results demonstrate that pterosin B is microbially degraded and that pterosin B is as unstable as ptaquiloside and hence cannot be used as an indicator for former presence of ptaquiloside in soil.

Fatty acids characterization, oxidative perspectives and consumer acceptability of oil extracted from pre-treated chia (Salvia hispanica L.) seeds

BackgroundChia (Salvia hispanica L.) seeds have been described as a good source of lipids, protein, dietary fiber, polyphenolic compounds and omega-3 polyunsaturated fatty acids. The consumption of chia seed oil helps to improve biological markers related to metabolic syndrome diseases. The oil yield and fatty acids composition of chia oil is affected by several factors such as pre-treatment method and size reduction practices. Therefore, the main mandate of present investigate was to study the effect of different seed pre-treatments on yield, fatty acids composition and sensory acceptability of chia oil at different storage intervals and conditions.MethodsRaw chia seeds were characterized for proximate composition. Raw chia seeds after milling were passed through sieves to obtain different particle size fractions (coarse, seed particle size ≥ 10 mm; medium, seed particle size ≥ 5 mm; fine, seed particle size ≤ 5 mm). Heat pre-treatment of chia seeds included the water boiling (100 C°, 5 min), microwave roasting (900 W, 2450 MHz, 2.5 min), oven drying (105 ± 5 °C, 1 h) and autoclaving (121 °C, 15 lbs, 15 min) process. Extracted oil from pre-treated chia seeds were stored in Tin cans at 25 ± 2 °C and 4 ± 1 °C for 60–days and examined for physical (color, melting point, refractive index), oxidative (iodine value, peroxide value, free fatty acids), fatty acids (palmitic, stearic, oleic, linoleic, α-linolenic) composition and sensory (appearance, flavor, overall acceptability) parameters, respectively.ResultsThe proximal composition of chia seeds consisted of 6.16 ± 0.24 % moisture, 34.84 ± 0.62 % oil, 18.21 ± 0.45 % protein, 4.16 ± 0.37 % ash, 23.12 ± 0.29 % fiber, and 14.18 ± 0.23 % nitrogen contents. The oil yield as a result of seed pre-treatments was found in the range of 3.43 ± 0.22 % (water boiled samples) to 32.18 ± 0.34 % (autoclaved samples). The oil samples at day 0 indicated the maximum color (R and Y Lovibond scale) value for oven drying while at storage day 60 (25 ± 2 °C), the highest color value was found for autoclave pre-treatment. The slightly increasing trend of color values for all treatments was observed during the storage period. The lowest iodine value (182.83 ± 1.18 g/100 g at storage day 0 & 173.49 ± 1.21 g/100 g at storage day 60, 25 ± 2 °C) was calculated for autoclaved samples while the maximum iodine value (193.42 ± 1.14 g/100 g at storage day 0 & 190.36 ± 1.17 g/100 g at storage day 60, 25 ± 2 °C) was recorded for raw chia samples. The significant increasing trend for all treatments was observed in case of peroxide value and free fatty acids production during storage. Maximum decrease in linoleic (35 %) and α-linolenic (18 %) fatty acids was observed in autoclaved samples. The oil from pre-treated seed samples obtained decreasing scores for sensory parameters throughout the storage period at different conditions.ConclusionsAs a result, chia seeds are an important source of lipids and essential fatty acids. The water boiling and high temperature processing of chia seeds provides instability to lipids during storage at room temperature. However, detailed investigation is required on the processing performance and storage stability of food products supplemented with pre-treated chia seeds and furthers their effect on biological system.

Ultrasonication as a rapid and high yield DNA extraction method for bacterial gene quantification by NanoGene assay

We demonstrated ultrasonication as a rapid and high yield DNA extraction method suitable for bacterial gene quantification by NanoGene assay. The NanoGene assay utilizes DNA hybridization in solution and a combination of magnetic beads and quantum dot nanoparticles. Unlike the existing gene quantification assays, the NanoGene method is capable of quantifying genes in the presence of environmental inhibitors and cell materials. The performance of the ultrasonication was compared with heating and freeze-thaw. They first were evaluated for their cell lysis capability in humic acids laden sand samples, via EtBr assay. Using autoclaved samples as a bench mark, their cell lysis capability were 106 ± 3, 68 ± 5, and 48 ± 15%, respectively. Morphological changes of cells for each method were also observed by FE-SEM. More importantly, ultrasonication performed significantly better (more than 3× fluorescence signal) than commercial DNA extraction methods during bacterial gene quantification in humic acids laden sand samples.

Effect of sterilization on the physical stability of brimonidine-loaded solid lipid nanoparticles and nanostructured lipid carriers

Nanoparticulate delivery systems have recently been under consideration for topical ophthalmic drug delivery. Brimonidine base-loaded solid lipid nanoparticles and nanostructured lipid carrier formulations were prepared using glyceryl monostearate as solid lipid and were evaluated for their physical stability following sterilization by autoclaving at 121°C for 15min. The objective of this work was to evaluate the effect of autoclaving on the physical appearance, particle size, polydispersity index, zeta potential, entrapment efficiency and particle morphology of the prepared formulations, compared to non-autoclaved ones. Results showed that, autoclaving at 121°C for 15min allowed the production of physically stable formulations in nanometric range, below 500nm suitable for ophthalmic application. Moreover, the autoclaved samples appeared to be superior to non-autoclaved ones, due to their increased zeta potential values, indicating a better physical stability. As well as, increased amount of brimonidine base entrapped in the tested formulations.

Corrosion Behavior of Zirconium, Titanium, and Their Alloys in Simulated Dissolver Solution of Fast Breeder Reactor Spent Nuclear Fuel Using Zircaloy-4 Mock-Up Dissolver Vessel

Long-term corrosion testing of a mock-up dissolver vessel to be employed in the aqueous reprocessing of spent nuclear fuels of fast breeder reactors has been initiated. In this work, a Zircaloy-4 (Zr-4) mock-up dissolver vessel was used as the testing facility to evaluate the corrosion rate of several candidate materials based on zirconium and titanium in the boiling and vapor phases of simulated dissolver solution (SDS) comprising fission and corrosion product ions in 11.5 M nitric acid. Several campaigns of 100, 250, 500, 1000, and 2500 h of operation were completed. The corrosion rates of the candidate materials are expressed both in micrometers per year (μm/yr) and mils per year (mils/yr). Zirconium-702, Zr-4, autoclaved Zr-4, and commercial pure titanium (CP-Ti) exhibited low corrosion rates of 0.08 to 0.23 μm/yr (0.003 to 0.009 mils/yr) in the as-received and welded conditions exposed to the boiling liquid phase of the dissolver solution for 2500 h. Whereas the CP-Ti and CP-Ti weld exhibited marginally higher corrosion rates of 1.0 μm/yr (0.04 mils/yr) and 1.9 μm/yr (0.075 mils/yr), respectively, in the vapor phase of the dissolver solution, the lowest corrosion rate of 0.08 μm/yr (0.003 mils/yr) was obtained for the autoclaved Zr-4 sample exposed to boiling SDS. Scanning electron microscope investigations did not reveal any corrosion attack for the titanium and zirconium samples. Laser Raman spectroscopic analysis confirmed that the origins of passivity of zirconium and titanium samples were due to the formation of ZrO2 and TiO2, respectively. However, the CP-Ti/AISI Type 304L stainless steel (SS 304L) and Zr-4/SS 304L dissimilar welds had undergone severe corrosion. Visual inspection of the Zr-4 dissolver vessel revealed no corrosion attack after operation for 2500 h. The results of this 2500-h campaign would serve as the baseline data for the analysis of future long-term campaigns.