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Magnetic, photocatalytic and antibacterial performance of ZnO NPs were enhanced as doped with Cu.

The present work focuses on the preparation, using a solution process, of flexible conductive nanocomposites based on polyurethane (PU)/polyaniline (PANI) with different mass percentages: 2, 3 and 4%. Because of the low conductivity of the PU + PANI films, these later were doped with inorganic NiCl2. PU + PANI undoped films were synthesized by a “one-shot” process. For doping process, PANI has been doped according to two different methods: The first one consists of the impregnation of the pristine PU + PANI film in a solution of inorganic salt dopant with a solvent (THF) during a soaking time, while the second method uses a “one-shot” process. The structural characterization and conductivity properties of the polymer blends were examined by differential scanning calorimetry, Fourier transform infrared spectroscopy and dielectric measurements spectroscopy. The results show that NiCl2 significatively increases the conductivity compared to pure PU + PANI blends, with better results using the second method of synthesis.

Hydrogenated natural rubber was prepared by the non-catalytic hydrogenation of natural rubber latex (NRL) with diimide generated from oxidation of hydrazine by hydrogen peroxide. The hydrogenated natural rubber (HNR) was characterized by Raman and FTIR spectroscopy. Raman and FTIR spectra showed that the chemical structure of hydrogenated natural rubber tends to be similar to ethylene-propylene-diene-monomer rubber. The thermogravimetric analysis revealed that the thermal-oxidative decomposition resistance of 65% HNR was close to those of EPDM and the thermal-oxidative decomposition behavior of 65% HNR was similar to EPDM. It is interesting that HNR can be a potential alternative to EPDM in terms of thermal-oxidative degradation properties.

In recent years, bacteriocins produced by lactic acid bacteria (LAB) have shown great potential for food safety preservation, especially for ready-to-eat products. In this study, bio-protective membrane was made from plasma-treated polypropylene film and functionalized with Carnobacterium divergens V41 (bacteriocin-producing strain) for the purpose of inhibiting Listeria monocytogenes growth in culture media and cold-smoked salmon (CSS) at refrigerated temperatures. In semi solid Brain Heart Infusion (BHI) agar, bio-protective plastic membrane led to a 3-Log reduction in L. monocytogenes count compared to the control, after 14 days of aerobic incubation at 8 °C. In vacuum-packed CSS, L. monocytogenes growth was inhibited by bio-protective plastic membrane after 7 days of storage at 4 °C and 21 days at 8 °C. Antilisterial activity of plastic membrane was even better than C. divergens cells added in CSS by direct spraying. Stability test has shown that bio-protective plastic membrane stored for 42 days at 4 °C still exerted antimicrobial activity against L. monocytogenes on BHI agar (2-Log reduction compared to the control). These preliminary results demonstrate that bio-protective plastic membrane can be used to control pathogenic bacteria in food products with potential industrial development.

Natural rubber (NR), a natural product from the Hevea brasiliensis tree, has been developed as a photosensitive mechanical modifier utilized in lithography-based three-dimensional (3D) printing technology. Here, we transformed NR to photosensitive NR (PNR) by incorporating acrylate groups via chemical modifications. The acrylated NR was blended with a commercial resin (CR) at various rubber contents (0 to 3 wt %) by a simple mixing approach. The blended resin was solidified to pattern the desired specimen using a digital light processing-based 3D printer. The effect of PNR contents on mechanical properties and thermal performance of the printed specimen compared to the neat CR was studied in this work. A printed sample containing 1.5 wt % PNR can increase the elongation ability and impact strength by approximately 59 and 116%, respectively, compared to the neat CR. The microstructure of the printed objects shows a heterogeneous surface consisting of dispersed rubber droplets and a continuous CR matrix. Two glass transition temperatures belonging to the rubber phase and the resin matrix can be observed. The thermal decomposition of the printed part decreased slightly with the elevation in the rubber content. Consequently, the synthesized photosensitive natural rubber could be used as a toughness modifier employed in ultraviolet-curable resin for the light-based 3D printing technology.

An analytical method was developed and validated for the determination of fludioxonil in rice samples. Rice samples for the study were collected from different regions of Pakistan. The method was based on safe and cost-effective extraction of fludioxonil from rice grains using acetone and methanol (1:1), efficient clean-up through homogenous mixture of acidic aluminum (12 g) and activated charcoal (1 g) followed by liquid chromatographic determination with UV detection. Quantification was performed on Prospher Star C18 (5 µm, 25 x 0.46 cm) column maintaining the temperature 40ºC and detector wavelength 212 nm using mobile phase 50:50 v/v methanol-water (pH 3.3) employing flow rate 1.0 mL.min-1 and 20 µL injection volume. The method showed linearity with correlation coefficient greater than 0.998. The proposed method was precisely validated for rice sample of all regions, showing recoveries higher than 98%. Rice samples collected from Badin, Multan, Hyderabad, Lahore, Jahania and Sarghoda was found to have fludioxonil residues 0.046, 0.045, 0,043, 0.040, 0.024 and 0.016 mg.kg-1 respectively, all below the maximum residual limit (MRL) level i.e. 0.05 mg.kg-1 whereas samples collected from Khanewal and Gularchi showed fludioxonil residue above MRL i.e 0.065 and 0.058 mg.kg-1 respectively. However, fludioxonil residues was not detected in rice sample collected from city Makhdumpur.

In this work, chemical modification of natural rubber in latex stage was focused on a green condition and to improve thermal, ozone and mechanical properties. Two chemical modifications including epoxidation followed by hydrogenation of natural rubber latex (NRL) were carried out continuously in one-pot system. The NRL was treated with in situ performic acid generated from the reaction of formic acid and hydrogen peroxide to obtain partially epoxidized product or epoxidized natural rubber (ENR) latex which was then further modified its residual unsaturated units using hydrazine and hydrogen peroxide to perform hydrogenation reaction. The chemical structure of the obtained modified rubber so called hydrogenated epoxidized natural rubber (HENR) was characterized by 1H-NMR and ATR-FTIR. Two types of HENR including HENR-1 (27 mol% degree of hydrogenation and 17 mol% degree of epoxidation) and HENR-2 (25 mol% degree of hydrogenation and 28 mol% degree of epoxidation) were subjected to investigate their thermal properties compared to the NR, ENR and hydrogenated NR (HNR). It was found that the modified NRs possess higher thermal property and increased Tg as compared to NR, due to both incorporation of epoxide units and reduced unsaturation of the molecular chain. The prepared HENRs were found to maintain the strain induced crystallization character which is the feature of NR. The vulcanized HENR-1 and HENR-2 showed superior tensile strength compared to vulcanized NR. In addition, the oil and ozone resistances of modified NRs were also improved. The preparation of HENR in one-pot latex system is a facile condition and save energy for any solvent recovery. The procedure can be considered as a potential green and sustainable development of NR.

A novel sensitive method for the detection of acetylcholinesterase inhibitors is presented by using unmodified gold nanoparticle coupled with dynamic light scattering (DLS). The hydrolysis of acetylcholine (ACh) mediated by acetylcholinesterase (ACHE) yields the choline, which influences the gold nanoparticles (AuNPs) aggregation, and triggered the increase of their average diameter. The inhibition of the enzyme by pesticides (paraoxon) produces lower yields of choline, leading to less or no AuNP aggregate formation. This study is the first to describe a homogeneous AuNPs-based DLS nanosensor for ultrasensitive detection of paraoxon by measuring ACHE activity. The average diameter and count rate of unmodified AuNPs decreased with the increasing concentration of paraoxon, with a detection limit of 75.5 pmol.L−1. These results suggest that this DLS assay based on unmodified AuNPs could be used in the future for measuring ACHE activity and for non-selective detection of trace amounts of all ACHE inhibitors.

New antimicrobial packaging films made from poly(lactic acid) (PLA) and natural rubber-graft-modified chitosan (chitosan-graft-polyacrylamide-2-methyl propane sulfonic acid (chitosan-g-PAMPS, Cg) loaded with different Ag+ concentrations (NR-g-Cg:Ag+, NCg:Ag) were prepared via a melt mixing process. After mixing NCg:Ag with PLA, the morphology of the compounds showed coarse surface with small particles of NCg:Ag dispersed in the PLA matrix. The size of the NCg:Ag particles found in the blends became smaller than that of the initial particles indicating partial compatibility of the blend between NCg:Ag and PLA. In addition, the compatibility of NCg:Ag and the remaining NCg:Ag particles may contribute to the improvement of the elongation at break, toughness and oxygen barrier properties of PLA films. The release of Ag+ on the order between 5 and 500 ng/cm2 was observed depending on the pH value of the solution and immersion time. However, the optimum concentration of the released Ag+, which was approximately 100 ng/cm2, affected the inhibition of microbial growth. The antimicrobial activity of the final materials was tested using colony count method with 5 bacterial species, both gram-negative and gram-positive bacteria. The blended film exhibited more than 99% reduction in numbers of all bacterial cells during 0–48 h of cultivation.

Raman spectroscopy including mapping technique appears as a powerful technique for the characterization of polymer blends like thermoplastic elastomers (TPEs) and thermoplastic vulcanizates (TPVs). The Raman spectra of polymers blends such as natural rubber/polypropylene (NR/PP) and 65% hydrogenated natural rubber/polypropylene (65%HNR/PP) were identified and the phase distribution was determined. The study was driven for the same type of blends in TPEs state and TPVs state obtained after to 2 different processes, either peroxide cure or sulfur cure. The morphology of TPEs and TPVs obtained by Raman spectroscopy were compared and confirmed using scanning electronic microscopy. Raman mapping shows that the phase morphology of NR/PP, 65%HNR/PP, were characterized as continuous rubber phase morphology of the thermoplastic elastomers (TPEs) and a fine dispersion of cross-linked rubber phase in a continuous matrix of the thermoplastic vulcanizates (TPVs). Raman spectroscopy is demonstrated to be a reference to determine the content ratio of each component in the TPVs. Moreover, Raman mapping could be used to calculate the phase size of cross-linked rubber phase dispersed in the thermoplastic vulcanizates (TPVs).

Sustainable composites derived from epoxidized natural rubber (ENR)/silver-substituted zeolite (AgZ)/poly(lactic acid) (PLA) blends possessing antibacterial activity were reported. ENR, herein, acted as an antibacterial promoter providing more hydrophilicity to the composites and facilitating water diffusion. Two methodologies were used to prepare composites, including solution casting (S) as well as solution casting followed by roll milling (SR). Both composites were compared in terms of morphology, AgZ dispersion, water absorption, and antibacterial activity. The shift of Tg and tan δ toward lower temperature of PLA composites consistently confirmed the compatibility between ENR and PLA by DSC and DMA results, respectively. The good AgZ distribution was observed in composites-SR, as confirmed by SEM/EDX. The results of agar disk diffusion susceptibility test showed that PLA, AgZ/PLA, and even ENR/AgZ/PLA composites-S showed no or less inhibition zone; meanwhile, ENR/AgZ/PLA composites-SR showed the significant inhibition zone against both Escherichia coli and Staphylococcus aureus. Besides, the antibacterial activity of the composites was required at least 5 wt% of AgZ. More than 98% inhibition of S. aureus growth by the composites-SR was observed during 2–24 h of cultivation, whereas AgZ/PLA provided the highest inhibition of only 75% at 24 h of cultivation. Hence, the incorporation of ENR enhances the bactericidal activity of the composites. In terms of mechanical properties, incorporating ENR into the composites decreased tensile modulus and strength, but increased the impact strength significantly. Therefore, the developed composites could be promising materials in food and biomedical fields in which antibacterial and impact resistance properties are required.

Microcellular natural rubber (NR) prepared using a supercritical CO2 technology is a promising alternative to replace traditional foaming agent due to environmental concern. Crucial parameters for the foaming process including CO2 saturation time (30, 60, 90, 120, 180) min, pressure (0, 8.5, 10.5, 12.5) MPa, temperature (45, 55, 65, 85) °C, and crosslinking characteristics of NR (pre-vulcanized time at 15 min and 30 min) were orderly conducted. The results obtained showed a decrement of average cell size (less than 10 μm), cell size distribution, and expansion ratio depending on an enhancement of saturation time and pressure. However, the increment of saturation temperature affected the increase in average cell size, cell size distribution, and expansion ratio. In case of the crosslinking behavior, an escalation of the pre-vulcanized time of rubber influenced the decrement in average cell size, cell size distribution and expansion ratio resulting from an elevation of matrix crosslinking.

Undoped ZnO and Zn0.97−xAl0.03MnxO (x = 0, 1, 2 and 3%) nanopowders (NPs) were synthesized by co-precipitation method. They were characterized by X-ray diffraction (XRD), Fourier transformed infrared (FTIR), Raman, UV–visible, photoluminescence (PL) and impedance spectroscopies. All samples exhibit a single phase wurtzite type. The average crystallite size lying between 22 and 42 nm was found to increase for all doped ZnO samples. The optical transmission in the visible region was improved due to doping. The optical band gap is in the range of 3–3.4 eV and was found to decrease up to 2% of Mn content but slightly increases with further doping. All PL spectra exhibit two emission peaks in UV and visible regions. The deconvolution of the visible emission peak reveals different emissions for all samples. An additional yellow emission is noticed for (Al + Mn) ZnO doped samples suggesting that the incorporation of aluminum and manganese in the zinc oxide host lattice enhances luminescence properties of ZnO. The ac conductivity (σac) was found to follow Jonscher’s power law and was improved with doping. Cole-Cole plots of all samples were suitably fitted to a circuit consisting in a parallel combination of a resistance and a constant phase element (CPE). Keywords: ZnO nanopowder, Doping, XRD, Optical properties, Conductivity

ZnO nanoparticles (ZnO NPs) were synthesized through surfactant free non-hydrolytic organic phase method in which zinc acetate and zinc acetylacetonate were selected as precursors. Structural and size analysis of the as-prepared nanoparticles performed on X-ray diffractometer, transmission electron microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy showed that the obtained nanoparticles were crystalline particles with all reflections matching to wurtzite. TEM images revealed that ZnO NPs from synthesis in which zinc acetate involved as precursor had a shape of sphere while zinc acetylacetonate resulted in rod-shaped nanoparticles. Reaction rates from catalytic activity test performed on Methylene Blue dye (MB) were found to be 2.99×10-2 min-1 and 1.98×10-2 min-1 for spherical and rod-shaped ZnO NPs, respectively. Antibacterial activity experiments shows rod-shaped ZnO NPs almost completely (99.75%) inhibited the growth of Escherichia Coli while only around 6.5% was survived after treatment of spherical ZnO NPs under same conditions.

International audience; New methods for pathogens identification are of growing interest in clinical and food sectors. The challenge remains to develop rapid methods that are more simple, reliable, and specific. Surface-enhanced Raman spectroscopy (SERS) appears to be a promising tool to compete with current untargeted identification methods. This article presents the intensive research devoted to the use of SERS for bacterial identification, from the first to the very recent published results. Compared to normal Raman spectroscopy, the introduction of nanoparticles for SERS acquisition introduces a new degree of complexity. Bacterial Raman fingerprints, which are already subject to high spectral variability for a given strain, become then very dependent on numerous experimental parameters. To overcome these limitations, several approaches have been proposed to prepare the sample, from the microbiological culture conditions to the analysis of the spectrum including the coupling of nanoparticles on the bacterial membrane. Main strategies proposed over the last 20 years are examined here and discussed in the perspective of a protocol transfer towards industry.

Organization of timely implementation of anti-deformation and repair work in tunnels and other objects of transport infrastructure requires a detailed analysis of the physical state of structures, and their individual elements. In recent years, a non-destructive ground penetrating radar (GPR) method is being increasingly used for this purpose. We present the results of GPR determination of electrophysical characteristics (refractive indices and electromagnetic radiation attenuation coefficients averaged within structural layers) of the highway road concretes in the tunnel using 1200–1700 MHz microwave radiation. The method of the GPR data processing is based on classical electrodynamics , and in practical implementation, it does not require additional integration with other geophysical or destructive testing methods. Various approaches have been applied in the calculations of electrophysical parameters of structural layers, which allowed estimating the errors of the computational schemes and approximations. The results obtained were used to clarify the dimensional parameters of the layers and determine the volumetric moisture content.

Red blood cells of mammals contain both raw carbonaceous material (proteins) and catalyzer precursor (iron atoms of metal-organic hemoglobin molecules) for Carbon nanotube (CNT) fabrication by the chemical vapor deposition method. To demonstrate the possibility of CNT fabrication by using blood as a single raw material, livestock (sheep) blood droplets on silicon substrates were used as samples for pyrolysis in an argon and argon + butane atmosphere at 300; 400; 500; 7000 C. Scanning electron microscope (SEM) images, of the product of pyrolysis at 500; 7000 C, magnified up to 20000 times, shows dense bushes consisting of nano-size rods. The length of the rods reached 50 μm; widths were around 400 nm and less. The two carbon bands centered at wavenumbers 1340 and 1580 cm-1 in the Raman spectra of samples recorded using a low power-incident red laser (638 nm), demonstrates increasing graphitization of carbon atoms with rise of pyrolysis temperature. Both the SEM images and the Raman spectra indicate increasing formation of CNT, with an increase of pyrolysis temperature from 400 to 7000 C. No evidence of CNT formation at 3000 C was found.

We present the first field application of a N₂O-based approach to correct for vertical mixing in the estimation of net community production (NCP) from mixed layer O₂ measurements. Using new ship-based observations of N₂O and biological oxygen saturation anomalies (ΔO₂/Ar) from the Subarctic Northeast Pacific, we provide refined mixed layer NCP estimates across contrasting hydrographic regimes and a comprehensive assessment of the methodological considerations and limitations of the approach. Increased vertical mixing coefficients at the base of the mixed layer, derived using N₂O measurements, corresponded with periods of heightened wind speed and coastal upwelling. Corrections were most significant in coastal regions where the vertical supply of low-O₂ water can otherwise falsely imply net heterotrophy from negative ΔO₂/Ar measurements. After correcting for the mixing flux, all coastal stations showed autotrophic signatures, with maximum NCP exceeding 100 mmol O₂ m⁻² d⁻¹ in the spring and summer. Vertical fluxes were lower in off-shelf waters but often contributed more than 50% to corrected NCP. At some oceanic stations, however, the cooccurrence of N₂O minima and O₂ maxima resulted in biased (overestimated) N₂O corrections. Evaluating vertical fluxes in these regions remains a challenge for ship-based studies. Nonetheless, our refined NCP estimates show better coherence with surface chlorophyll, temperature, and mixed layer depth than uncorrected values. Potential mixed layer N₂O production introduces some uncertainty in the approach, but errors are likely to be small. Ultimately, this work provides rationale for the adoption of the N₂O correction to refine NCP estimates, particularly in coastal waters.

The present research evaluates the social inclusion component of the Brazilian National Program for the Production and Use of Biodiesel’s (PNPB) by studying its impact on the livelihoods of family farmers in the country’s Northeast region of Bahia. The overall objective is to critically analyze the social sustainability aspect of the program by including different dimensions of social exclusion in its analysis. More specifically, this thesis examines the PNPB’s effectiveness in helping family farmers in Bahia achieve positive livelihood outcomes. In terms of theoretical perspective, the Sustainable Livelihoods Framework (SLF) is employed while existing research and government data are analyzed using a descriptive method. The findings of this thesis indicate that the PNPB is predominantly designed in economic terms, largely ignoring the multi-dimensional nature of social exclusion. In this sense, the results suggest that the lack of success of the program in the country’s Northeast region can be in part explained by its failure to adopt coherent and sustainable strategies that go beyond market insertion and income generation. In particular, the research demonstrated that the PNPB’s lack of participatory approach and the absence of social and cultural considerations, along with inadequate technical extension services, hampered the program’s success in the region. Based on these results, this research highlights the need for a broader approach when it comes to promoting social inclusion, as well as the importance of taking into account and developing the cultural, social and political capital of family farmers in Bahia. In this sense, this thesis emphasizes the importance of recognizing that social exclusion is a complex and multi-faceted phenomenon, which calls for improving the ways with which we evaluate and deepen the understanding of the livelihoods of family farmers in Bahia.

The ozone stability of partially hydrogenated natural rubbers (HNRs) was evaluated. HNRs with the hydrogenation levels of 14, 33 and 65 mol% including with vulcanization systems of peroxide and sulfur on ozone stability comparing with natural rubber (NR) and ethylene-propylene-diene-rubber (EPDM) vulcanizates were studied. The chemical structures of rubber vulcanizates were characterized by Raman spectroscopy. The surface cracks were observed by Raman optical microscopy. The results clearly exhibited that the ozone stability of HNRs vulcanizates was much greater than that of the NR vulcanizates. The difference between the integral intensities of C=C bonds of isoprene units in rubber chains by Raman spectroscopy before and after ozone exposed was minimized with the degree of hydrogenation. The depth of cracking observed by three-dimensional (3D) modes clearly decreased with an increase in the degree of hydrogenation, while no cracks on the surface of EPDM were found. These findings indicated that ozone stability increased with the degree of hydrogenation. Regarding the effect of vulcanizing systems, sulfur cure showed greater resistance to ozone degradation than peroxide cure.

The impact of a stroke and the individual neuronal regeneration capacity varies highly from patient to patient. In this context, a consistent scoring method is very desirable to quantify the motion impairment and to evaluate the result of rehabilitation. Traditional internationally recognized clinical scores (e.g. Barthel Index, Berg Balance Scale, etc.) are widely used but fail to assess the functional mobility or to assist clinicians in the planning of personalized therapy. For this reason, a new score (the ReHabX score) has been developed, which evaluates 6 functional gait motion criteria, namely “trunk movement”, “arm movement”, “leg movement”, “gait speed”, “gait fluency”, and “stability/risk of falling”. The gait of 59 stroke patients was measured using motion capture technology, and evaluated by a team of medical experts using the ReHabX score. 168 parameters (so-called “features”) were identified and extracted from each measurement. This list of features included conventional gait metrics, discretized joint angles, and non-traditional gait parameters designed to represent specific pathological gait characteristics. Due to the good reliability and normal distribution of the scorings, a linear model was chosen for the reconstruction of the clinicians’ ratings from the features. By a stepwise multilinear regression algorithm, features which allowed the reproduction of the functional scores provided by the medical experts were selected. For each scoring criteria, 3 to 6 features were inserted in the corresponding linear model. The accuracy of the numerical models was evaluated using both the traditional measures of the goodness of fit, and a novel technique. In this context, a novel so-called “bubble plot” was developed, which allows the visualization of the level of agreement among the raters together with the comparison of the numerical scoring with the average medical score. It was thereby shown that the determination of the individual criteria using the gait features accurately corresponds to the reliability of the medical experts. The numerical scores obtained are a valuable contribution to the diagnostics of motion impairment that ensure objectivity and reproducibility. They may support the creation of a personalized therapy and speed-up the post-stroke recovery process. Dissertation, Universität Duisburg-Essen, 2016

Highlights: • We studied the evolutions of structure for TiO{sub 2} thin film as changes with Nb doping and temperatures. • Up to 800 °C, the grain size of Nb{sub 0.1}Ti{sub 0.9}O{sub 2} is smaller than for pure TiO{sub 2} because doped Nb hinders the growth of the TiO{sub 2} grains. • There was no formation of the rutile phase at high temperature. • Nb doped TiO{sub 2} films have high electron densities at 400–700 °C. • Nb dope extends the absorbance spectra of TiO{sub 2} which leads to the band gap reduce. - Abstract: Acid-catalyzed sol–gel and spin-coating methods were used to prepare Nb-doped TiO{sub 2} thin film. In this work, we studied the effect of niobium doping on the structure, surface, and absorption properties of TiO{sub 2} by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectometry (XRR), X-ray photoelectron spectroscopy (XPS), Raman, and UV–vis absorption spectroscopy at various annealing temperatures. EDX spectra show that the Nb:Ti atomic ratios of the niobium-doped titania films are in good agreement with the nominal values (5 and 10%). XPS results suggest that charge compensation is achieved by the formation of Ti vacancies. Specific niobium phases are not observed, thus confirming thatmore » niobium is well incorporated into the titania crystal lattice. Thin films are amorphous at room temperature and the formation of anatase phase appeared at an annealing temperature close to 400 °C. The rutile phase was not observed even at 900 °C (XRD and Raman spectroscopy). Grain sizes and electron densities increased when the temperature was raised. Nb-doped films have higher electron densities and lower grain sizes due to niobium doping. Grain size inhibition can be explained by lattice stress induced by the incorporation of larger Nb{sup 5+} ions into the lattice. The band gap energy of indirect transition of the TiO{sub 2} thin films was calculated to be about 3.03 eV. After niobium doping, it decreased to 2.40 eV.« less

We report the preparation and characterization of spherical core-shell structured Fe3O4-Au magnetic nanoparticles, modified with two component self-assembled monolayers (SAMs) consisting of 3-mercaptophenylboronic acid (3-MBA) and 1-decanethiol (1-DT). The rapid and room temperature synthesis of magnetic nanoparticles was achieved using the hydroxylamine reduction of HAuCl4 on the surface of ethylenediaminetetraacetic acid (EDTA)-immobilized iron (magnetite Fe3O4) nanoparticles in the presence of an aqueous solution of hexadecyltrimetylammonium bromide (CTAB) as a dispersant. The reduction of gold on the surface of Fe3O4 nanoparticles exhibits a uniform, highly stable, and narrow particle size distribution of Fe3O4-Au nanoparticles with an average diameter of 9 +/- 2 nm. The saturation magnetization value for the resulting nanoparticles was found to be 15 emu/g at 298 K. Subsequent surface modification with SAMs against glucoside moieties on the surface of bacteria provided effective magnetic separation. Comparison of the bacteria capturing efficiency, by means of different molecular recognition agents 3-MBA, 1-DT and the mixed monolayer of 3-MBA and 1-DT was presented. The best capturing efficiency of E. coli was achieved with the mixed monolayer of 3-MBA and 1-DT-modified nanoparticles. Molecular specificity and selectivity were also demonstrated by comparing the surface-enhanced Raman scattering (SERS) spectrum of E. coli-nanoparticle conjugates with bacterial growth media.

This study aimed to test Raman (400–1800 cm − 1 ) and Infra-red (1900–500 cm − 1 ) spectroscopies followed by statistical analysis (principal component analysis) to detect molecular changes induced by antibiotics (ampicillin, cefotaxime – cell wall synthesis inhibitors, tetracycline – protein synthesis inhibitor, ciprofloxacin – DNA synthesis inhibitor) against Escherichia coli TOP10. In case of ampicillin and cefotaxime, a decrease in protein bands in both Raman (1240, 1660 cm − 1 ), and IR spectra (1230, 1530, 1630 cm − 1 ), and an increase in carbohydrate bands (1150, 1020 cm − 1 ) in IR spectra were observed. Tetracycline addition caused an increase in nucleic acid bands (775, 1478, 1578 cm − 1 ), a sharp decrease in phenylalanine (995 cm − 1 ) in Raman spectra and the amide I and amide II bands (1630, 1530 cm − 1 ) in IR spectra, an increase in DNA in both Raman (1083 cm − 1 ) and IR spectra (1080 cm − 1 ). Regarding ciprofloxacin, an increase in nucleic acids (775, 1478, 1578 cm − 1 ) in Raman spectra and in protein bands (1230, 1520, 1630 cm − 1 ), in DNA (1080 cm − 1 ) in IR spectra were detected. Clear discrimination of antibiotic-treated samples compared to the control was recorded, showing that Raman and IR spectroscopies, coupled to principal component analysis for data, could be used to detect molecular modifications in bacteria exposed to different classes of antibiotics. These findings contribute to the understanding of the mechanisms of action of antibiotics in bacteria.

In this work, two sets of samples were considered: field samples collected from local waste wood and synthetic samples made by mixing clean wood (including oak, beech, poplar) with typical organic pollutants: creosote, polychlorinated byphenils (PCBs), pentachlorophenol (PCP), cypermethrin, dodecyl dimethyl ammonium chloride (DDAC). Vibrational spectroscopy techniques were tested to detect organic pollutants in wood items. Raman and infrared spectroscopies were showed as fast, non-destructive and non-invasive fingerprint techniques for detection of organic molecules. Associated with principal component analysis, we have shown the evidence of quick detection of and discrimination of polluted wood items by kinds and versus concentration.

In this work, we present a new complete method using Surface Enhanced Raman Spectroscopy (SERS) and chemometrics for the qualitative and quantitative detection of pesticides by measuring the acetylcholinesterase (ACHE) activity. The Raman SERS is not only used for measuring the ACHE activity, but also for the direct detection of pesticides individually and for their identification. Gold nanoparticles (AuNPs) were used as dynamic SERS substrates for sensitive monitoring of ACHE activity in the presence of very low levels of organophosphate and carbamate pesticides, chemical warfare agents that are known to be ACHE inhibitors. The lowest detectable level for paraoxon was determined at 4.0 x 10(-14)M and 1.9 x 10(-9)M for carbaryl. The use of the enzyme allowed limits of detection for both pesticides that were much lower than the limits obtained by direct SERS analysis of the pesticides. The system shows a linear relationship between the intensity band at 639 cm(-1) and pesticide concentration. These results suggest that this biosensor could be used in the future for the non-selective detection of all ACHE inhibitors at very low concentrations with possible identification of the inhibitor. (C) 2016 Elsevier B.V. All rights reserved.

In this study, the interactions between microplastics, chosen among the most widely used in industry such as polypropylene (PP) and high-density polyethylene (HDPE), and a model freshwater microalgae, Chlamydomas reinhardtii, were investigated. It was shown that the presence of high concentrations of microplastics with size >400 μm did not directly impact the growth of microalgae in the first days of contact and that the expression of three genes involved in the stress response was not modified after 78 days. In parallel, a similar colonization was observed for the two polymers. However, after 20 days of contact, in the case of PP only, hetero-aggregates constituted of microalgae, microplastics and exopolysaccharides were formed. An estimation of the hetero-aggregates composition was approximately 50% of PP fragments and 50% of microalgae, which led to a final density close to 1.2. Such hetero-aggregates appear as an important pathway for the vertical transport of PP microplastics from the water surface to sediment. Moreover, after more than 70 days of contact with microplastics, the microalgae genes involved in the sugar biosynthesis pathways were strongly over-expressed compared to control conditions. The levels of over-expression were higher in the case of HDPE than in PP condition. This work presents the first evidence that depending on their chemical nature, microplastics will follow different fates in the environment.

The detection of pollutants in the environment by chemical, physical or biological methods is a necessary part of European policy and biosensors should play a role in the monitoring of such pollution. A portable optical biosensor, namely Lumisens 2, is described for the on line detection of pollutants. Lumisens 2 features three main parts: (I) a central unit, (II) a disposable card where bacteria are immobilized and inserted into unit 1, and (III) an acquisition unit to control the device. The first card used in this study (TBTcard) included the bioluminescent Escherichia coli strain TBT3 harboring the truncated luxAB genes from Vibrio harveyi. TBT3 specifically detects organotin compounds (tributyltin or dibutyltin). Lumisens 2 was validated according to the on line measurement of bioluminescence with a continuous flow of sample. The biosensor was able to detect 2 μM of TBT on line in 400 min and after a contact time of 1 h with the pollutant, the accumulation effect of the matrix allowed us to detect 1 nM of this toxic biocide. Because any bioluminescent bacteria can be immobilized in the cards, Lumisens 2 could become a multipurpose optical biosensor for the detection of either the overall toxicity of a sample or one particular pollutant.

Fast monitoring and control quality of food products become increasingly important for public health. Among foodborne pathogenic microorganisms, bacteria are the most common foodborne pathogens in which the currently used methods are time consuming, labour-intensive and costly. This work aims to develop a new biochip potentially used for an assessment of bacterial contamination on food product. An assessment for bacterial detection employs simple FTIR spectroscopic analysis with a complimentary surface characterization by SEM technique. The biochip based on carboxylic acid functionalized polyurethane (PU) film was synthesized for bacterial detection in particular Salmonella Typhimurium. The PU in this study was synthesized from the reaction of the alcohol groups of hydroxyl telechelic natural rubber based oligomer with the isocyanate groups of 2,4-toluene diisocyanate. The carboxylic acid functional group was incorporated into the PU chain by addition of dimethylol propionic acid as a chain extender during PU preparation. The PU film having different degree of carboxylic acid was explored for the detection of S. Typhimurium. The structural and morphological changes of the PU film after loading of the bacteria were successfully detected using ATR-FTIR and SEM, respectively. The PU film developed is considered a rapid tool for S. Typhimurium detection and has a potential application for rapid food control quality.

Antarctica represents a frontier of science and human exploration on planet Earth. This remote and poorly studied region is home to highly productive marine ecosystems, which are being significantly impacted by rapid warming and ice melt. Using both video and photography, Dr. Tortell will present results from a recent Antarctic expedition documenting the response of surface water biological processes to a range of climate-dependent environmental factors. Insights derived from this work will be important for understanding potential impacts of climate change on Canada’s marine Arctic ecosystems.

The non-catalytic hydrogenation of natural rubber (NR) and two epoxidized NRs (ENRs) i.e. ENR-22 and ENR-40 containing 22 and 40 mol% of epoxide, respectively, was carried out using p-toluenesulfonylhydrazide (TSH) as a hydrogenating agent. A two-fold molar excess of TSH compared with unsaturated units of the rubber was used. The evidence of hydrogenation is a decrease in the intensity of the characteristic signal of the carbon–carbon double bond stretching vibration of the rubber in both the Raman and FT-IR spectra. The percentage hydrogenation was successfully determined by Raman spectroscopy since the vibrational mode of the carbon–carbon unsaturation is strongly Raman active. The progress of the hydrogenation could be monitored by means of the techniques mentioned above as a function of reaction time. The maximum degree of hydrogenation of NR is ∼89% whereas in the case of ENR-22 and ENR-40 it reaches 94 and 96%, respectively. Solid-state 13C NMR spectroscopy was also used to confirm the microstructure characteristics of the hydrogenated rubbers. 13C NMR analysis showed that cis–trans isomerization of carbon–carbon unsaturations occur during hydrogenation. Copyright © 2004 John Wiley & Sons, Ltd.

The diimide hydrogenation of natural rubber (NR) was studied by using p-toluenesulfonylhydrazide (TSH) as a diimide-releasing agent. The microstructure and the percentage of hydrogenation were studied by Raman, 1 H-NMR and 13 C-NMR spectroscopic techniques. Quantitative measurements on fraction of hydrogenated part gave the results in good agreement by using these techniques. The results indicated that percent hydrogenation increased with increasing of reaction time and about 80-85 % hydrogenation was achieved when a two-fold excess of TSH was used. The vibrational characteristic of C=C bond of NR is strongly Raman active and noted at 1663 cm -1 . The decrease of this signal was clearly observed during the progress of hydrogenation but the vibrational frequency of the cis and trans structures of the trisubstituted olefin unit of NR can not be differentiated by this technique. While 1 H- and 13 C-NMR analysis showed that cis-trans isomerization of carbon-carbon unsaturation of NR occurred during hydrogenation.

In this paper, we present a new device composed of a biological part included in an original opto-electronic bioreactor described here in detail. It allows the simultaneous measurement of bioluminescence and optical density of a bioluminescent bacterial culture without any sampling. The cell density is measured through a laser diode and a photodiode by using a numerical synchronous detection and the bioluminescence with a photomultiplier. The experimental results are presented through the validation of the measurement principle using the Vibrio fischeri bacterium which was cultivated under continuous culture conditions. Very good correlation between manual and automatic measurements processed with the instrument has been demonstrated. The device could be applied to the realization of biosensors with any bioluminescent cells.

The structural and vibrational properties of above mentioned crystals were determined using X-ray powder diffraction and Raman scattering experiments. At room temperature hydrate layered perovskites: Rb{sub 2}MnF{sub 5}{center_dot}H{sub 2}O and K{sub 2}FeF{sub 5}{center_dot}H{sub 2}O exhibit orthorhombic--Cmcm (D{sub 2h}{sup 17}) and monoclinic--C2/c (C{sub 2h}{sup 6}) symmetry. Their structure is built up of MnF{sub 6} or FeF{sub 5}{center_dot}H{sub 2}O octahedra forming trans-linked zig-zag chains or hydrogen bonded zig-zag chains along the major crystallographic direction [0 0 1], respectively. To confirm crystal structures and to describe lattice dynamics of these compounds the vibrational normal modes (in {gamma} point of first Brillouin zone) were calculated on the base of the group theory analysis and compared with the spectra obtained from Raman scattering experiments. A relatively good reliability was obtained for both X-ray powder diffraction and Raman scattering.

This article presents a new device devoted to the simultaneous measurement of bioluminescence and optical density of a bioluminescent bacterial culture. It features an optoelectronic bioreactor with a fully autoclavable module, in which the bioluminescent bacteria are cultivated, a modulated laser diode dedicated to optical density measurement, and a detection head for the acquisition of both bioluminescence and optical density signals. Light is detected through a bifurcated fiber bundle. This setup allows the simultaneous estimation of the bioluminescence and the cell density of the culture medium without any sampling. The bioluminescence is measured through a highly sensitive photomultiplier unit which has been photometrically calibrated to allow light flux measurements. This was achieved by considering the bioluminescence spectrum and the full optical transmission of the device. The instrument makes it possible to measure a very weak light flux of only a few pW. The optical density is determined throug...

The hydrogenation of natural rubber (NR) and various epoxidized natural rubbers (ENR) was investigated by using diimide generated in situ from the thermal decomposition of p-toluenesulfonylhydrazide (TSH) in oxylene solution at 135°C. 1 H-NMR analysis indicated that approximately 85-95% of hydrogenation was performed with a twofold excess of TSH. FT-IR and Raman spectroscopy were employed to confirm the microstructure characteristics of the hydrogenated rubbers. The cis-trans isomerization was also observed by 1 H- and 13 C-NMR. The signal in 1 H-NMR of the epoxide group of the ENR disappears after hydrogenation while the signal of the opened epoxide ring product was detected. This may be due to the epoxide ring opening reaction caused by the p-toluenesulfinic acid by-product. The high temperature of the reaction condition leads to chain degradation in both NR and ENR. Thermal behaviors of the hydrogenated rubbers characterized by differential scanning calorimetry showed that the glass transition temperatures of the hydrogenated rubbers were increased about 10-20°C compared with the starting rubbers.