Agar Solution Research Articles

Antimicrobial test of roselle (hibiscus sabdariffa L.) ethanol extract againts porphyromonas gingivalis and streptococcus sanguis using agar method (in vitro study)

The use of natural materials in the world of health tends to increase every single year, including in dentistry. Due to the increased of resistance to antibiotics, the development and new innovations to obtain a new antimicrobial agent. Some potential sources of plants have been studied. One of the natural plants is used as drinks, food, medicine and antimicrobial agent is Hibiscus sabdariffa Linn commonly known as Roselle. Several major Gram-negative bacteria are related to periodontal disease such as Porphyromonas gingivalis (P.gingivalis), The dominant species of Gram-positive including Streptococcus sanguis(S.sanguis). The purpose of this in vitro study is to evaluate the Roselle ethanol extract against P.gingivalis bacteria (Gram negative bacteria) and S. sanguis (Gram positive bacteria) with a concentration of 2.5%, 5%, 7.5% and 10%. The in vitro study of antibacterial effectiveness of Roselle (Hibiscus sabdariffa L.) ethanol extract on P.gingivalis and S. sanguis. Natrium Agar (NA) solution was poured into a glass plate which had previously been sterilized and then left in place until the medium solidified. P.gingivalis and S.sanguis bacterial cultures were inoculated with inscribed which had solidified. Then put paper disk which had previously been saturated with Roselle extract samples with a concentration of 2.5%, 5%, 7.5% and 10%, and the negative control at the surface of the medium (Ampicillin) and incubated for 1 day. Clear zone is formed then observed and measured. There are 24 samples, consisting of 12 samples P.gingivalis and S.sanguis 12 samples, given intervention roselle flower extract with four types of concentrations to determine the minimum inhibitory consentration (MIC). The observations show that the extensive zone of inhibition concentration of 2.5% a broad zone of inhibition is the smallest among other concentration, both of S.sanguins and P.gingivalis. Meanwhile, the average increases the broad zones of inhibition of P.gingivalis followed by increasing concentrations of roselle flower extract, making it the largest broad zones of inhibition are shown at a concentration of 10%, However, the bacteria S.sanguins, shows that vast zone of greatest inhibition was found at a concentration of 7.5%. The results of this research showed that the ethanol extract of roselle effectively inhibits P. gingivalis as Gram-positive bacteria atconcentrations of 10% and S. sanguins at a concentration of 7.5%. Iit can be concluded that the ethanol extract of roselle flowers effective at inhibiting Gram positive and Gram negative bacteria.

Preparation and characterization of agar-based nanocomposite films reinforced with bimetallic (Ag-Cu) alloy nanoparticles

Agar-based active nanocomposite films were prepared by incorporating silver-copper (Ag-Cu) alloy nanoparticles (NPs) (0.5–4wt%) into glycerol plasticized agar solution. Thermo-mechanical, morphological, structural, and optical properties of the nanocomposite films were characterized by texture analyzer, differential scanning calorimetry (DSC), scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, and surface color measurement. Tensile strength and the melting temperature of the film increased linearly with NPs loading concentration. Color, transparency and UV barrier properties of agar films were influenced by the reinforcement of Ag-Cu NPs. XRD analysis confirmed the crystalline structure of the Agar/Ag-Cu nanocomposite films, whereas the smoothness and the homogeneity of film surface strongly reduced as observed through the SEM. The nanocomposite films exhibited a profound antibacterial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Salmonella enterica sv typhimurium) bacteria. Overall, the agar nanocomposite films could be used as packaging material for food preservation by controlling foodborne pathogens and spoilage bacteria.

SU‐G‐IeP1‐06: Estimating Relative Tissue Density From Quantitative MR Images: A Novel Perspective for MRI‐Only Heterogeneity Corrected Dose Calculation

Purpose:To explore the feasibility of extracting the relative density from quantitative MRI measurements as well as estimate a correlation between the extracted measures and CT Hounsfield units.Methods:MRI has the ability to separate water and fat signals, producing two separate images for each component. By performing appropriate corrections on the separated images, quantitative measurement of water and fat mass density can be estimated. This work aims to test this hypothesis on 1.5T.Peanut oil was used as fat‐representative, while agar as water‐representative. Gadolinium Chloride III and Sodium Chloride were added to the agar solution to adjust the relaxation times and the medium conductivity, respectively. Peanut oil was added to the agar solution with different percentages: 0%, 3%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%. The phantom was scanned on 1.5T GE Optima 450W with the body coil using a multigradient echo sequences. Water/fat separation were performed while correcting for main field (B0) inhomogeneity and T2* relaxation time. B1+ inhomogeneities were ignored. The phantom was subsequently scanned on a Philips Brilliance CT Big Bore. MR‐corrected fat signal from all vials were normalized to 100% fat signal. CT Hounsfield values were then compared to those obtained from the normalized MR‐corrected fat values as well as to the phantom for validation.Results:Good agreement were found between CT HU and the MR‐extracted fat values (R2 = 0.98). CT HU also showed excellent agreement with the prepared fat fractions (R2=0.99). Vials with 70%, 80%, and 90% fat percentages showed inhomogeneous distributions, however their results were included for completion.Conclusion:Quantitative MRI water/fat imaging can be potentially used to extract the relative tissue density. Further in‐vivo validation are required.

Markers-traits association for iron toxicity tolerance in selected Indonesian rice varieties

Nugraha Y, Utami DW, Rosdianti I, Ardie SW, Ghulammahdi M, Suwarno, Aswidinnoor H. 2016. Markers-traits association for iron toxicity tolerance in selected Indonesian rice varieties. Biodiversitas 17: 753-763. Ferrous iron toxicity is a mineral disorder frequently occurring under flooded soils condition where rice is cultivated. Here we study identification the Single Nucleotide Polymorphism (SNPs) markers associated with iron toxicity tolerance characters. The phenotypical data was collected from exploiting of twenty-four rice genotypes that were grown under Yoshida + 0.2% agar solution with treatment of 400 mg. L-1 Fe2+ and control conditions. The same genotypes were grown in iron toxicity acute and control sites at Taman Bogo, Lampung Province, Indonesia. The Principle Component Analysis (PCA) of the phenotypic data showed that 18 rice genotypes were selected representing grouping of related characters to iron toxicity condition. The genotyping of selected genotypes was carried out using multiplexes of 384 SNPs Golden Gate Illumina© assay. We identified, TBGI380435 which located on 14.45 Mbp of chromosome 9 was associated to leaf bronzing and relative shoot weight characters in the greenhouse experiment. The marker was associated with heavy metal transport detoxification (HTDT). The results are expected to assist in locating the potential candidate genes or Fe toxicity tolerance and to allow for precise marker-assisted selection. This research will serve for rice improvement through marker-assisted breeding and genomic selection in Indonesia. Keywords: Golden gate assay, grain yield, leaf bronzing scores, principle component analysis, single nucleotide polymorphism Abbreviations: SNPs = Single Nucleotide Polymorphisms, AM = Association Mapping, LD= Linkage Disequilibrium, GG= Golden Gate Assay, NGS= Next Generation sequencing ,QTL = Quantitative Trait Loci, LBS = Leaf Bronzing Score, PCA = Principle Component Analysis, SES = Standard Evaluation System For Rice, GLM = General Linear Model, PC = Principle Component, HTDT = Heavy Metal Transport Detoxification

Photothermal effects of gold nanoparticles induced by light emitting diodes

Gold nanoparticles (AuNPs) have a great potential for biomedical application due to the superior photothermal efficiency. The photothermal effects of AuNPs in different heated media under a polychromatic and three monochromatic light emitting diode (LED) illuminations were experimentally investigated to explore the possible use of LED for the thermotherapy treatment. The results show that the noticeable temperature increase of the heated media can be achieved by the injection of AuNPs induced by LED illumination. The selection of the LED wavelength depends not only on the absorption peak wavelengths of the AuNP with different sizes but also on the absorption coefficient of the heated media. Either a smaller AuNP size, higher AuNP concentration, or higher power density can lead to a higher temperature increase. The AuNP aggregation occurred in the heated egg white, agar solution, and blood leads to the lower temperature increase comparing with the heated water. Moreover, the LED light with a wavelength of 635 nm results in better heating for the heated blood and biological tissue in vitro comparing with other selected wavelengths due to the lower light absorption of the blood, deeper penetration in biological tissues, and the light absorption rate of AuNP to a certain degree.

Biocompatibility evaluation of sputtered zirconium-based thin film metallic glass-coated steels.

Thin film metallic glasses comprised of Zr48Cu36Al8Ag8 (at.%) of approximately 1.5 μm and 3 μm in thickness were prepared using magnetron sputtering onto medical grade 316L stainless steel. Their structural and mechanical properties, in vitro corrosion, and antimicrobial activity were analyzed. The amorphous thin film metallic glasses consisted of a single glassy phase, with an absence of any detectable peaks corresponding to crystalline phases. Elemental composition close to the target alloy was noted from EDAX analysis of the thin film. The surface morphology of the film showed a smooth surface on scanning electron microscopy and atomic force microscopy. In vitro electrochemical corrosion studies indicated that the zirconium-based metallic glass could withstand body fluid, showing superior resistance to corrosion and electrochemical stability. Interactions between the coated surface and bacteria were investigated by agar diffusion, solution suspension, and wet interfacial contact methods. The results indicated a clear zone of inhibition against the growth of microorganisms such as Escherichia coli and Staphylococcus aureus, confirming the antimicrobial activity of the thin film metallic glasses. Cytotoxicity studies using L929 fibroblast cells showed these coatings to be noncytotoxic in nature.

EXTRACTION OF AGAR FROM Gelidium P (RHODOPHYTA) AND GREEN SYNTHESIS OF AGAR /SILVER NANOPARTICLES

Physicochemical and rheological characters of agar sample extracted from(rhodophyta)Gelidium sp. collected from the Egyptian coast of the red sea has been investigated. Agar yielded 29% on dry biomass basiswith pretreatment using 0.15 M sodium hydroxide. Agar surface texture was investigated through the usage of the scanning electron microscopy (SEM). Agar is a white flakes and threads, insoluble in cold water, but it swells absorbing much water making hydrogels.The morphology of the agar surface texture was investigated using scanning electron microscopy (SeM).The dynamic rheological measurements of agar solutions (2, 3, 4 mg agar/ml) as a function of shear rate were achieved at 85o C and let to cool gradually (1.5oC/ min), with the maximum values of viscosity as following 1.26, 3.12 and 5.18cP, respectively at shear rate of 40 sec-1.Agr solutions revieled the presence of non-Newtonian fluid material demonstrating shear thinning (Pseudoplastic) flow behavior in aqueous solution (2 mg agar/ml) giving up to formation of an elastic gel. At higher concentrations (3 & 4 mg agar/ml) induce shear thickening representd as viscosity increases as shear rate increased giving up to Newtonian fluid behavior.The AgNPs were synthesized and characterized on the bases of spectral (FT-IR and UV-visible), morphological (Transmission electron microscopy-TEM), zeta potential and atomic force microscopy (AFM) measurements. The resulted Agar Nanoparticles (AgNPs) are showing gradualproperities as gradual increase in absorbance with increasing the intensity of the yellow-brown color, it showed peak maximum located at 410 nm with absorbance value of 0.579.The average size distributions of AgNPs were found to be .It was illustrated that zeta potential value for AgNPs was -28.0 mV.

Functional PDMS Composite Microbridges for Temperature Sensing Applications

Microstructures provide excellent sensing and actuating capabilities due to their high surface to volume ratio and have brought about important advancements in life sciences research [1-3]. The development of electrically-conductive polymer composites for such sensors and actuators as well as rapid fabrication techniques will result in microstructures with better transduction, low cost of production and flexibility [4, 5]. Conventional microfabrication techniques for such transducers are photolithography, reactive ion etching (RIE), laser ablation, and focussed ion beam etching. However these techniques are limited by the requirement of multiple processing steps (photolithography and RIE) or serial processing with specialized equipment (laser ablation and focussed ion-beam etching). In this work we report a low-cost, rapid and convenient technique to microfabricate electrically-conductive Iron-Polydimethylsiloxane (Fe-PDMS) microbridges using agar as the sacrificial material and further demonstrate the temperature sensing property of this polymer composite. Fabrication of the Fe-PDMS microbridges by the sacrificial agar technique is illustrated schematically in Fig. 1. A rectangular mold containing a 20mm×0.7mm×0.2mm channel and three pairs of sidewall through-holes (800µm in diameter) was manufactured via 3D printing (Fig.1a-i). Glass capillary guide rods with diameters of 65µm, 240µm and 350µm were inserted into the sidewall though-holes and passed through the channel (Fig.1a-ii). The guide rods functioned as master molds for the sacrificial agar, creating cavities for the Fe-PDMS composite to flow through. A 4% agar solution was prepared and poured into the rectangular mold (Fig.1a-iii). Following the room-temperature curing of the agar, the guide rods were removed horizontally and the agar replica was carefully de-molded, exposing the cylindrical cavities to be filled with Fe-PDMS composite (Fig.1a-iv). The agar replica was transferred into a petri dish (Fig.1a-v). The Fe-PDMS composite was prepared by mixing 80wt% iron particles (200 mesh size) with Sylgard 184 pre-polymer (10:1 elastomer-curing agent ratio). This composite was carefully casted into the aforementioned cylindrical cavities using assistive capillary flow. Undoped Sylgard 184 pre-polymer (10:1 elastomer-curing ratio) was then casted on the entire structure and cured at 37oC for 24 hours (Fig. 1a-vi). The cured structure was then immersed in a 100˚C water bath (Fig. 1a-vii) to dissolve the sacrificial agar and dried to form the suspended microbridge structures (Fig. 1a-viii) before plasma bonding to another flat PDMS layer (Fig. 1a-ix). The scanning electron microscope images of the fabricated microbridges are shown in Fig. 2. The thickness of the fabricated suspended bridges were measured and compared against their respective guide rod thicknesses (Fig. 3). The average thicknesses of the 65µm and 240µm microbridges showed a high precision in fabrication with a standard deviation of ~12µm from the guide rods. The larger deviation of the 350µm microbridge may be attributed to the size range (1-75 µm) of the iron particles in the Fe-PDMS composite which is currently under investigation. Uniform particle size would ensure better consistency in microbridge thicknesses. The temperature sensing ability of the Fe-PDMS composite was experimentally verified as well. A 24 AWG copper wire was used to provide electrical interconnection with the composite. The current-voltage (IV) characteristics of the Fe-PDMS composite in the input voltage range of 1-20V was measured by a Keithley 2410 source meter at four equilibrium temperatures of 45, 50, 60 and 70˚C applied externally via a hot plate. Each equilibrium temperature level produced a distinctive near-ohmic IV curve (Fig. 4a) with a positive correlation between the temperature and electrical conductivity. The obtained mean resistivities (Fig. 4b) imply a positive coefficient of resistance that is analogous to metals. The sacrificial agar fabrication technique in conjunction with the properties of the developed Fe-PDMS polymer composite will be suitable for development of low-cost and flexible electrodes and microstructures in microfluidic devices for thermo-electric temperature sensing and actuating applications. References F. Mei, S. P. J. Fancy, Y.-A. a Shen, J. Niu, C. Zhao, B. Presley, E. Miao, S. Lee, S. R. Mayoral, S. a Redmond, A. Etxeberria, L. Xiao, R. J. M. Franklin, A. Green, S. L. Hauser and J. R. Chan, Nat. Med., 2014, 20, 954–960.F. Liu, Y. Piao, J. S. Choi and T. S. Seo, Biosens. Bioelectron., 2013, 50, 387–392.S. Ito, T. Yasui, Y. Okamoto, N. Kaji and M. Tokeshi, Proc. 16th Int. Conf. Miniaturized Syst. Chem. Life Sci., 2012, 1234–1236.Gong X, Wen W, Polydimethylsiloxane-based conducting composites and their applications in microfluidic chip fabrication, Biomicrofluidics 2009, 3, 012007, pp1-14Calvert P, Deepak D, Patra P, Agrawal A, Sawhney A, Conducting Polymer and Conducting Composite Strain Sensors on Textiles. Molecular Crystals and Liquid Crystals, 2008; 484 (1), pp291-302 Figure 1

Development of a water-stable agar-based diet for the supplementary feeding of cleaner fish ballan wrasse (Labrus bergylta) deployed within commercial Atlantic salmon (Salmon salar) net-pens

Abstract The aim of this project was to develop a water-stable and palatable diet for the supplementary feeding of wrasse deployed in salmon sea-pens using a gelling agent mixed with a manufactured dry-feed component. Three binders (gelatine from cold water fish skin, beef gelatin and agar-agar) were compared for water-gel strength over a range of concentrations. Gel formed using agar was found to be significantly stronger than the other binders tested. An experimental aqua-feed made using a grinded, dry ingredient mix binded with 20 g/L agar solution at 1/1.6 (w/v) ratio and offered as blocks within individual feeders was water-stable for 7 days when deployed fresh or following a week of preservation at -20 °C. Farmed ballan wrasse in tanks fed on the agar-based diet within 2 days of deployment. Wild wrasse stocked in salmon sea-pens at low density (1.2–2.1%), up to 4 weeks prior the start of the trial and not previously fed a manufactured diet first ingested the agar feed within 2 weeks and total feed intake significantly increased afterwards. Feed intake was significantly higher from feeders placed within a small feeding shelter made of artificial kelp than within the large wrasse shelter. No nutrient leaching after water immersion and no alterations in the fatty acid profile after preparation of the experimental feed was found. A manufactured grinded ingredient mix binded with 20 g/L agar solution at a 1/1.6 (w/v) ratio and offered within static feeders is proposed as the basis of a novel supplementary feeding methodology for cleaner fish wrasse deployed in salmon sea-pens. This methodology has the potential to facilitate wrasse feeding and to allow the monitoring of feed intake to safeguard the health, welfare and delousing activity of the biological stock over the salmon rearing cycle.

In-vitro diagnosis of single and poly microbial species targeted for diabetic foot infection using e-nose technology.

BackgroundEffective management of patients with diabetic foot infection is a crucial concern. A delay in prescribing appropriate antimicrobial agent can lead to amputation or life threatening complications. Thus, this electronic nose (e-nose) technique will provide a diagnostic tool that will allow for rapid and accurate identification of a pathogen.ResultsThis study investigates the performance of e-nose technique performing direct measurement of static headspace with algorithm and data interpretations which was validated by Headspace SPME-GC-MS, to determine the causative bacteria responsible for diabetic foot infection. The study was proposed to complement the wound swabbing method for bacterial culture and to serve as a rapid screening tool for bacteria species identification. The investigation focused on both single and poly microbial subjected to different agar media cultures. A multi-class technique was applied including statistical approaches such as Support Vector Machine (SVM), K Nearest Neighbor (KNN), Linear Discriminant Analysis (LDA) as well as neural networks called Probability Neural Network (PNN). Most of classifiers successfully identified poly and single microbial species with up to 90% accuracy.ConclusionsThe results obtained from this study showed that the e-nose was able to identify and differentiate between poly and single microbial species comparable to the conventional clinical technique. It also indicates that even though poly and single bacterial species in different agar solution emit different headspace volatiles, they can still be discriminated and identified using multivariate techniques.

Magnetic resonance imaging of electrolysis.

This study explores the hypothesis that Magnetic Resonance Imaging (MRI) can image the process of electrolysis by detecting pH fronts. The study has relevance to real time control of cell ablation with electrolysis. To investigate the hypothesis we compare the following MR imaging sequences: T1 weighted, T2 weighted and Proton Density (PD), with optical images acquired using pH-sensitive dyes embedded in a physiological saline agar solution phantom treated with electrolysis and discrete measurements with a pH microprobe. We further demonstrate the biological relevance of our work using a bacterial E. Coli model, grown on the phantom. The results demonstrate the ability of MRI to image electrolysis produced pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E. Coli model grown on the phantom. The results are promising and invite further experimental research.

The Efficiency of UVC Radiation in the Inactivation of Listeria monocytogenes on Beef-Agar Food Models.

The aim of this study is to evaluate the effect of meat content and surface smoothness on the deactivation of Listeria monocytogenes in beef-agar food models achieved by shortwave ultraviolet (UVC) light. Food models with various meat contents were made using chopped beef slices and agar solution. Prepared models together with a Listeria selective agar (LSA) plate and a slice of cooked beef were inoculated with L. monocytogenes and then exposed to UVC light. Population of Listeria reduced to below the level of detection on the LSA plates. As the content of beef in the beef-agar models increased, more L. monocytogenes cells survived. Survival was greatest on the treated cooked slice of beef. To better understand the effect of surface irregularities, a white light interferometer was used to analyse the surface smoothness of beef-agar media and LSA plates. No correlation was observed between the surface roughness of seven out of nine types of produced beef-agar media and the degree of inactivation resulting from UVC radiation at the given dose, whereas, less bacterial cells were killed as beef content of the food models increased. The findings of the current study show that the chemical composition of the treated sample also plays an important role in pathogen resistance and survival, meaning that two samples with similar surface irregularities but different chemical composition might produce very different inactivation results when exposed to UVC light.

Fungicide Impact on in vitro Germination of Basidiospores of Puccinia horiana, the Causal Agent of Chrysanthemum White Rust

Puccinia horiana is an actionable pathogen that, upon diagnosis, triggers an eradication protocol combining destruction of symptomatic chrysanthemums and a strict fungicide regime for asymptomatic plants. Symptoms typically appear during the fall as growers prepare to ship their crops. To expand the list of effective fungicides and develop fungicide sensitivity baselines, we screened in vitro germination of P. horiana basidiospores in 0.05% water agar solution amended with varying concentrations of 14 fungicides: azoxystrobin, boscalid + pyraclostrobin, fluoxastrobin, mancozeb, mandestrobin, metconazole, myclobutanil, propiconazole, tebuconazole, triadimefon, trifloxystrobin, trifloxystrobin + triadimefon, and triticonazole. Leaves with pustules ready to sporulate were affixed to petri plate lids over bases containing fungicide-amended agar. After 2 days in the dark, percent basidiospore germination was assessed. Concentrations required for 50% germination (EC50) grouped according to fungicide mode of action. Benzimidazoles exhibited EC50 values ranging from 9 to 244 ppm, while strobilurins ranged from 2 to 27 ppb. Mancozeb exhibited an EC50 of 7 ppm, and chlorothalonil was 205 ppb. Combinations of strobilurins with other modes of action exhibited EC50 values in the same range as the strobilurins. These data provide a baseline for monitoring resistance development to P. horiana over time. Accepted for publication 15 January 2015. Published 7 April 2015.

The Efficacy of Voriconazole Eye Drops Reconstituted in Sterile Water for Injection

Purpose: To investigate the efficacy of voriconazole 1% eye drops reconstituted in sterile water for injection and stored in the fridge or room conditions and correlate the results to bibliographic data. Methods: Voriconazole powder was reconstituted with water for injection, in order to prepare a 1% solution. The solution was separated in sterile vials stored in the fridge or in the cupboard. Malt extract agar solutions were prepared with the addition of this voriconazole solution to achieve concentrations of 1 μg/ml, 2 μg/ml and 4 μg/ml and the same procedure was repeated after one and after two weeks. Petri plates were inoculated with standardized solutions of Candida albicans, Aspergillus fumigatus, Alternaria alternata, Fusarium solani and Fusarium oxysporum. The fungal growth was compared to the control plates, which contained only malt extract agar without voriconazole. Results: The voriconazole solutions remained effective for more than two weeks (18 days), independently of the storage conditions. The concentration of 1μg/ml was effective against Candida albicans and Aspergillus fumigatus, the 2 μg/ml against Alternaria alternata (and until the 17th day also against Fusarium oxysporum but not on the 18th day) and the 4 μg/ml against Fusarium oxysporum but not against Fusarium solani. Conclusion: The reconstituted with sterile water for injection voriconazole eye drops are effective against various fungi. Fusarium solani was resistant up to the concentration of 4 μg/ml. The susceptibility of the examined fungi varies and thus, considerations should be raised about the combination with other routes of administration in order to achieve the appropriate drug concentrations in the eye. There was no significant difference in the effectiveness of voriconazole solutions in relation to the storage conditions.

In vitro corrosion and biocompatibility screening of sputtered Ti40Cu36Pd14Zr10 thin film metallic glasses on steels.

The growth of multi-component thin film metallic glasses (TFMGs) of Ti40Cu36Pd14Zr10 (at.%) alloys fabricated using magnetron sputtering on bioimplantable 316 L stainless steel substrates has been investigated. The vapor-solid quenching during sputtering enables the amorphous phases to be formed. The amorphous films consist of a single glassy phase, as evidenced by a broad hump and no detectable crystalline peaks as observed from XRD and selective area electron diffraction (SAED) patterns. The average surface roughness (Ra) of the coated film as observed from AFM was 0.3 nm. Nanohardness of about 7.7 GPa and Young's modulus of 110 GPa were measured from nanoindentation analysis. The potentiodynamic polarization and impedance measurements showed that coated stainless steel substrates have higher corrosion resistance compared to uncoated SS substrate in simulated body fluid (SBF) solution. The cytotoxicity studies using L929 fibroblast cells showed that these coatings were non-cytotoxic in nature. The interactions between the coated surface and bacteria were investigated by agar diffusion method, solution suspension and wet interfacial contact methods.

A split flow chamber with artificial sediment to examine the below-ground microenvironment of aquatic macrophytes

We present a new experimental set-up enabling fine-scale examination of how changing environmental conditions affect the below-ground biogeochemical microenvironment of aquatic macrophytes. By means of microsensor and planar optode technology, the influence of plant-mediated radial O2 release on the below-ground chemical microenvironment of Zostera muelleri and Halophila ovalis was determined in high spatio-temporal resolution. The seagrass specimens were cultured in a new split flow chamber with artificial sediment made of a deoxygenated seawater–agar solution with added sulphide. Microelectrode measurements revealed radial O2 release from the root–shoot junction of both Z. muelleri and H. ovalis during both light stimulation and darkness, resulting in a rapid decrease in H2S concentration, and a significant drop in pH was observed within the plant-derived oxic microzone of Z. muelleri. No radial O2 release was detectable from the below-ground tissue of Z. muelleri during conditions of combined water-column hypoxia and darkness, leaving the plants more susceptible to sulphide invasion. The spatial O2 heterogeneity within the immediate rhizosphere of Z. muelleri was furthermore determined in two dimensions by means of planar optodes. O2 images revealed a decrease in the spatial extent of the plant-derived oxic microzone surrounding the below-ground tissue during darkness, supporting the microelectrode measurements. This new experimental approach can be applied to all rooted aquatic plants, as it allows for direct visual assessment of the below-ground tissue surface during microprofiling, while enabling modification of the above-ground environmental conditions.

Preparation of oxidized agar and characterization of its properties

A series of oxidized agars with different carboxyl content were prepared, and their properties were determined and analyzed. The results showed that the gelling temperature, the optical rotation and the apparent viscosity of the agar solution, and the melting temperature, the strength, the hardness, the fracturability, the springiness, the chewiness and the gumminess of agar gel all decreased except that the cohesiveness increased after oxidation. The gel skeleton structures of agar before and after oxidation were all of the porous network structures, but the pores of gel skeleton structure became smaller and denser after oxidation.

Tunable Porous Hydrogels from Cocontinuous Polymer Blends

Hydrogels embedded with networks of fully interconnected pores were prepared with microporous polylactide (PLA) molds obtained by extracting the polystyrene (PS) phase in melt-processed cocontinuous blends of PLA and PS. Quiescent annealing of the blends prior to the PS extraction allowed control over the average pore diameter from ∼1 to ∼500 μm for the PLA molds. Solutions of agar or alginate were injected within the molds and gelled in situ. Porous gels were obtained by extracting the PLA molds and X-ray microtomography was employed to characterize their microstructure. Water removal/uptake cycles were fully reversible with very fast kinetics. Freeze-drying yielded ultraporous materials without modification of the macroscopic dimensions, and rehydration yielded back porous hydrogels. It was possible to scale up the technique by using extrusion and injection molding equipment. This versatile new method allows extensive control over the gels’ porosity parameters and the use of various gel chemistries.

Chitosan-triphosphate nanoparticles for encapsulation of super-paramagnetic iron oxide as an MRI contrast agent

Super-paramagnetic iron oxide nanoparticles (SPIONPs) were encapsulated at various concentrations within chitosan-triphosphate (SPIONPs-CS) nanoparticles using an ionotropic gelation method. The encapsulation of SPIONPs within CS nanoparticles enhanced their dispersion ability in aqueous solution, with all particles being lower than 130nm in size and having highly positive surface charge. The SPIONPs-CS nanoparticles exhibited crystalline structure and super-paramagnetic behavior, as seen in non-encapsulated SPIONPs. The morphology of SPIONPs-CS nanoparticles showed that they almost spherical in shape. The effect of phantom environments (culture medium and 3% agar solution) on either T1 or T2 weighted MRI was investigated using a clinical 1.5T MRI scanner. The results revealed that 3% agar solution showed relaxation values higher than the culture medium, leading to a significant decrease in the MR image intensity. Our results demonstrated that the SPIONPs-CS nanoparticles can be applied as tissue-specific MRI contrast agents.

Enhancement of Germination and Growth of Slickspot Peppergrass in a New Medium with Two Compost Organic Fractions

Slickspot peppergrass (Lepidium papilliferum) is an herbaceous biennal or possibly perennial “rare” endemic plant of the southwestern Idaho high desert listed as a threatened species. This plant establishes perennial seed banks, with seeds remaining dormant and viable for several years. This study aimed to enhance the germination and early growth of this plant by adopting a new medium, a nutrient-enriched agar solution, also added with humic acid (HA) and water-extractable organic matter (WEOM) fractions isolated from a green compost (GC) and a mixed compost (MC). The germination percentage of slickspot peppergrass in this new medium was much greater than that obtained in previous studies. Further, the addition of GC-HA in the medium enhanced significantly the germination and early growth of this plant. The addition of GC-WEOM and MC-WEOM were beneficial only on plant growth for at least 7 months.