Increasing the angular sensitivity of two-dimensional photonic crystal based sensors to arbitrary values.

A new design of photonic crystal (PhC) for optical sensing using guided mode resonance (GMR) is presented. We theoretically show that angular sensitivity is inversely proportional to the group velocity of the probed mode and can be made arbitrarily high in a properly designed PhC. PhCs made in polycrystalline diamond on insulator are fabricated. The angular sensitivity dependence is validated. We measured modes with group velocity of c/80 at a wavelength of 800 nm. A sensitivity in the order of 500 ° per refractive index unit is inferred, a value much larger than the one usually encountered in PhCs.

Carboxylated nanodiamonds can be used as negative reference in in vitro nanogenotoxicity studies.

Nanodiamonds (NDs) are promising nanomaterials for biomedical applications. However, a few studies highlighted an in vitro genotoxic activity for detonation NDs, which was not evidenced in one of our previous work quantifying γ-H2Ax after 20 and 100 nm high-pressure high-temperature ND exposures of several cell lines. To confirm these results, in the present work, we investigated the genotoxicity of the same 20 and 100 nm NDs and added intermediate-sized NDs of 50 nm. Conventional in vitro genotoxicity tests were used, i.e., the in vitro micronucleus and comet assays that are recommended by the French National Agency for Medicines and Health Products Safety for the toxicological evaluation of nanomedicines. In vitro micronucleus and in vitro comet assays (standard and hOGG1-modified) were therefore performed in two human cell lines, the bronchial epithelial 16HBE14o- cells and the colon carcinoma T84 cells. Our results did not show any genotoxic activity, whatever the test, the cell line or the size of carboxylated NDs. Even though these in vitro results should be confirmed in vivo, they reinforce the potential interest of carboxylated NDs for biomedical applications or even as a negative reference nanoparticle in nanotoxicology. Copyright © 2017 John Wiley & Sons, Ltd.

Surface-sensitive diamond photonic crystals for high-performance gas detection.

Diamond slotted photonic crystal (PhC) cavities were fabricated and used for gas detection. They exhibit wavelength sensitivity reaching a 350 nm per unit change of the refractive index of the gaseous environment of the PhC. With a simple oxidized surface termination, diamond PhCs display an ultrahigh sensitivity to the surface adsorption of polar molecules. Gaseous concentrations as low as 80 parts per million (ppm) of hexanol vapor in nitrogen are probed, and a detection limit in the ppm range is inferred, demonstrating a high interest of such devices for trace sensing.

Boron doped diamond biotechnology: from sensors to neurointerfaces.

Boron doped nanocrystalline diamond is known as a remarkable material for the fabrication of sensors, taking advantage of its biocompatibility, electrochemical properties, and stability. Sensors can be fabricated to directly probe physiological species from biofluids (e.g. blood or urine), as will be presented. In collaboration with electrophysiologists and biologists, the technology was adapted to enable structured diamond devices such as microelectrode arrays (MEAs), i.e. common electrophysiology tools, to probe neuronal activity distributed over large populations of neurons or embryonic organs. Specific MEAs can also be used to build neural prostheses or implants to compensate function losses due to lesions or degeneration of parts of the central nervous system, such as retinal implants, which exhibit real promise as biocompatible neuroprostheses for in vivo neuronal stimulations. New electrode geometries enable high performance electrodes to surpass more conventional materials for such applications.

Integration of multimodal MRI data via PCA to explain language performance.

OBJECTIVE/METHODS: Neuroimaging research has predominantly focused on exploring how cortical or subcortical brain abnormalities are related to language dysfunction in patients with neurological disease through the use of single modality imaging. Still, limited knowledge exists on how various MRI measures relate to each other and to patients' language performance. In this study, we explored the relationship between measures of regional cortical thickness, gray-white matter contrast (GWMC), white matter diffusivity [mean diffusivity (MD) and fractional anisotropy (FA)] and the relative contributions of these MRI measures to predicting language function across patients with temporal lobe epilepsy (TLE) and healthy controls. T1- and diffusion-weighted MRI data were collected from 56 healthy controls and 52 patients with TLE. By focusing on frontotemporal regions implicated in language function, we reduced each domain of MRI data to its principal component (PC) and quantified the correlations among these PCs and the ability of these PCs to explain the variation in vocabulary, naming and fluency. We followed up our significant findings by assessing the predictive power of the implicated PCs with respect to language impairment in our sample. RESULTS: We found significant positive associations between PCs representing cortical thickness, GWMC and FA that appeared to be partially mediated by changes in total brain volume. We also found a significant association between reduced FA and increased MD after controlling for confounding factors (e.g., age, field strength, total brain volume). Reduced FA was significantly associated with reductions in visual naming while increased MD was associated with reductions in auditory naming scores, even after controlling for the variability explained by reductions in hippocampal volumes. Inclusion of FA and MD PCs in predictive models of language impairment resulted in significant improvements in sensitivity and specificity of the predictions. CONCLUSIONS: Quantitative MRI measures from T1 and diffusion-weighted scans are unlikely to represent perfectly orthogonal vectors of disease in individuals with epilepsy. On the contrary, they exhibit highly intercorrelated PCs in their factor structures, which is consistent with an underlying pathological process that affects both the cortical and the subcortical structures simultaneously. In addition to hippocampal volume, the PCs of diffusion weighted measures (FA and MD) increase the sensitivity and specificity for determining naming impairment in patients with TLE. These findings underline the importance of combining multimodal imaging measures to better predict language performance in TLE that could extend to other patients with prominent language impairments.

Carboxylated nanodiamonds are neither cytotoxic nor genotoxic on liver, kidney, intestine and lung human cell lines.

Although nanodiamonds (NDs) appear as one of the most promising nanocarbon materials available so far for biomedical applications, their risk for human health remains unknown. Our work was aimed at defining the cytotoxicity and genotoxicity of two sets of commercial carboxylated NDs with diameters below 20 and 100 nm, on six human cell lines chosen as representative of potential target organs: HepG2 and Hep3B (liver), Caki-1 and Hek-293 (kidney), HT29 (intestine) and A549 (lung). Cytotoxicity of NDs was assessed by measuring cell impedance (xCELLigence® system) and cell survival/death by flow cytometry while genotoxicity was assessed by γ-H2Ax foci detection, which is considered the most sensitive technique for studying DNA double-strand breaks. To validate and check the sensitivity of the techniques, aminated polystyrene nanobeads were used as positive control in all assays. Cell incorporation of NDs was also studied by flow cytometry and luminescent N-V center photoluminescence (confirmed by Raman microscopy), to ensure that nanoparticles entered the cells. Overall, we show that NDs effectively entered the cells but NDs do not induce any significant cytotoxic or genotoxic effects on the six cell lines up to an exposure dose of 250 µg/mL. Taken together these results strongly support the huge potential of NDs for human nanomedicine but also their potential as negative control in nanotoxicology studies.

Role of frontotemporal fiber tract integrity in task-switching performance of healthy controls and patients with temporal lobe epilepsy.

The objective of this study is to investigate the relationships among frontotemporal fiber tract compromise and task-switching performance in healthy controls and patients with temporal lobe epilepsy (TLE). We performed diffusion tensor imaging (DTI) on 30 controls and 32 patients with TLE (15 left TLE). Fractional anisotropy (FA) was calculated for four fiber tracts [uncinate fasciculus (UncF), arcuate fasciculus (ArcF), dorsal cingulum (CING), and inferior fronto-occipital fasciculus (IFOF)]. Participants completed the Trail Making Test-B (TMT-B) and Verbal Fluency Category Switching (VFCS) test. Multivariate analyses of variances (MANOVAs) were performed to investigate group differences in fiber FA and set-shifting performances. Canonical correlations were used to examine the overall patterns of structural-cognitive relationships and were followed by within-group bivariate correlations. We found a significant canonical correlation between fiber FA and task-switching performance. In controls, TMT-B correlated with left IFOF, whereas VFCS correlated with FA of left ArcF and left UncF. These correlations were not significant in patients with TLE. We report significant correlations between frontotemporal fiber tract integrity and set-shifting performance in healthy controls that appear to be absent or attenuated in patients with TLE. These findings suggest a breakdown of typical structure-function relationships in TLE that may reflect aberrant developmental or degenerative processes.

Surface properties of hydrogenated nanodiamonds: a chemical investigation.

Hydrogen terminations (C-H) confer to diamond layers specific surface properties such as a negative electron affinity and a superficial conductive layer, opening the way to specific functionalization routes. For example, efficient covalent bonding of diazonium salts or of alkene moieties can be performed on hydrogenated diamond thin films, owing to electronic exchanges at the interface. Here, we report on the chemical reactivity of fully hydrogenated High Pressure High Temperature (HPHT) nanodiamonds (H-NDs) towards such grafting, with respect to the reactivity of as-received NDs. Chemical characterizations such as FTIR, XPS analysis and Zeta potential measurements reveal a clear selectivity of such couplings on H-NDs, suggesting that C-H related surface properties remain dominant even on particles at the nanoscale. These results on hydrogenated NDs open up the route to a broad range of new functionalizations for innovative NDs applications development.

Changes in fiber tract integrity and visual fields after anterior temporal lobectomy.

OBJECTIVE: To investigate postoperative changes in fiber tract integrity in patients with temporal lobe epilepsy (TLE) following anterior temporal lobectomy (ATL) and to determine whether postoperative changes are 1) stable vs progressive and 2) related to visual field defects. METHODS: Diffusion tensor imaging (DTI) was obtained in 7 patients with TLE before, 2 months after, and 1 year after ATL. Changes in fractional anisotropy (FA) were evaluated in a whole-brain voxel-wise analysis, as well within specific fiber tracts. Repeated-measures analysis of variance was performed to examine the time course of FA changes within ipsilateral and contralateral fiber tracts. Quantitative visual field analysis was performed to determine whether decreases in regional FA were related to the extent or location of visual field defects. RESULTS: Patients showed decreased FA 2 months post-ATL in ipsilateral fiber tracts transected during surgery (parahippocampal cingulum, uncinate fasciculus, inferior longitudinal fasciculus, and fornix), as well as in fiber tracts not directly transected (inferior fronto-occipital fasciculus and corpus callosum). Additional decreases in FA were not observed from 2 months to 1 year post-ATL. Visual field defects in most patients were characterized by incomplete quadrantanopsias. However, FA reductions in one patient extended into temporo-occipital cortex and the splenium of the corpus callosum and were associated with a complete hemianopia. CONCLUSIONS: Wallerian degeneration is apparent 2 months following unilateral ATLs in ipsilateral fibers directly and indirectly affected during surgery. These changes do not appear to progress over the course of a year, but may correlate with the nature and extent of postoperative visual field defects.

Induction of supernumerary ribs with sodium salicylate.

Although many chemical agents induce supernumerary ribs (SNR), few efforts have been published examining the induction of SNR in the presence or absence of maternal toxicity and the effect of dose on SNR length. A single administration of sodium salicylate on Day 9 of pregnancy at different dose levels (120, 180, 240, and 300 mg/kg) was used to induce SNR in the thoracolumbar region. At 180, 240, and 300 mg/kg, body weight loss was observed for dams following the administration, associated with reduced food consumption. The mean litter incidence of SNR in the control groups ranged between 0 and 17.1% and in the treated groups (from 180 to 300 mg/kg) between 50.5 and 88.6%. At 120 mg/kg, no adverse effects were noted in dams and the incidence of SNR was in the range of the control groups. Furthermore, in the three highest dose groups, increased incidences of 27 presacral vertebrae (PSV) were noted. In most instances, fetuses with 27 PSV had extra ribs whereas fetuses with 26 PSV tended to have rudimentary ribs. The distinction of SNR between rudimentary and extra ribs is usually based on a ratio of the length of 14th to 13th rib of 0.50. However, this value does not reflect the separation of the apparent bimodal distribution of SNR induced by sodium salicylate. A ratio of 0.35, which corresponds to the superior limit of the SNR of control fetuses, seemed to better define the two populations of SNR.

Optimum incubation conditions of the domestic guinea fowl egg.

1. During artificial incubation of 8000 guinea fowl eggs, the effects of temperature, relative humidity, rate of inflowing air and age of the laying flocks were determined. 2. Total duration of incubation was divided into setter (0 to 24 days) and hatcher (25 to 28 days) periods. Eggs transferred at the end of the setter period, (ET, % of fertile eggs) and hatching rate (HR, % of transferred eggs) were calculated, as well as the total hatching rate expressed as percentage of fertile eggs. 3. In the range 36 to 39 degrees C, temperature affected significantly (P < 0.001) ET and HR, with optima at 37.2 and 37.0 degrees C +/- 0.1 degrees C respectively. 4. During incubating period, relative humidity in the range 40 to 64% (water vapour partial pressure, PH2O = 17 to 34 Torr at 36 to 39 degrees C), significantly (P < 0.001) affected the total diffusive water loss and hatchling mass, both expressed as percentage of fresh egg mass. ET was significantly affected by water loss, the highest ET being for water loss of 13.3 +/- 0.5%. Optimal relative humidity was calculated to be 48 to 52% (PH2O = 23 to 25 Torr at 37.2 degrees C). 5. The rate of inflowing air significantly (P < 0.001) affected HR, with an optimum at 3.1 LSTPD/(h.egg). 6. The age of the laying flock significantly (P < 0.001) increased water loss; this was explained by a parallel increase of the mass specific shell conductance to water vapour. 7. Finally optimum incubation conditions were deduced, giving total hatching rates of 78 to 81% of fertile eggs, improving by 5 to 8% the best results obtained routinely in commercial practice.

Oxygen uptake and chorioallantoic blood flow changes during acute hypoxia and hyperoxia in the 16 day chicken embryo.

Oxygen consumption rate (MO2) of hen eggs was measured on incubation day 16 (37.8 degrees C, 55% humidity) during acute exposure (90 min) to ambient hyperoxia (FI02 = 0.42) or hypoxia (FIO2 = 0.105). During the last part of these exposures, an H2 washout method was used to estimate relative changes in chorioallantoic membrane (CAM) blood flow, taking as an index the net change in the H2 washout rate constant between any experimental condition and the circulation arrested egg. Doubling normoxic FIO2 increased MO2 to an asymptotic value which was 4% above the normal (P less than 0.05; MO2 in normoxia = 890 mumols/h) even after correcting for the normoxic increase in MO2 with time during development (delta MO2/delta t = 21.5 mumols/h2; P less than 0.001). Halving FIO2 reduced MO2 calculated in the same way to 388 mumols/h. The estimate of the CAM blood flow, relative to normoxia, was 1.12 in hyperoxia (not significant, P = 0.05) and 0.68 in hypoxia (P less than 0.001). The limited changes in CAM blood flow and MO2 during hyperoxia indicate that they are both already close to their maximal values in normoxia. During acute hypoxia the 16 day embryo behaves as an oxygen-conformer; however, the small relative decrease in MO2 per unit of the flow index observed during hyperoxia suggests that the embryo can regulate its CAM blood flow to a small extent. The survival of the embryo and its recovery from hypoxia without a detectable O2 repayment suggest small if any anaerobic regulatory pathways and indicate a true metabolic depression.

Cellulose Fermentation by an Asporogenous Mutant and an Ethanol-Tolerant Mutant of Clostridium thermocellum.

Two mutants of Clostridium thermocellum were isolated after UV light mutagenesis. Mutant A1, selected as asporogenous, exhibited a fermentation pattern similar to that of the wild type. However, at pH 6.5, the mutant degraded 12% more cellulose than did the wild type, leading to enhanced ethanol production. Mutant 647, selected as ethanol tolerant, was able to grow in medium containing 4% ethanol. During the early stage of the exponential growth phase, ethanol was produced as the main product, up to a concentration of about 9 g/liter. After 3 days of culture, 48.3 g (89% of the initial amount) of degraded cellulose per liter was fermented into 12.7 g of ethanol per liter.

Enhanced Cellulose Fermentation by an Asporogenous and Ethanol-Tolerant Mutant of Clostridium thermocellum.

A mutant of Clostridium thermocellum isolated after UV mutagenesis and selection for resistance to fluoropyruvate was found to be asporogenous and ethanol tolerant. The mutant was also an ethanol hyperproducer, able to ferment 63 g of cellulose into 14.5 g of ethanol per liter of medium. The ratio of ethanol to total organic acids produced by the mutant was increased, and H(2) production was decreased. Culture conditions were optimized for ethanol production by the new strain.

[Augmentation of nitrogen efficiency and hyperphagia associated with refeeding after prolonged fast in the domestic goose]. / Augmentation du rendement azoté et hyperphagie associées à la réalimentation après un jeûne prolongé chez l'oie domestique.

The domestic goose is hyperphagic after a fast resulting in a 40% decrease in body mass (a decrease similar to that during breeding anorexia). Food intake is maximum on the 8th day of refeeding. As it is then an average of 2.5 times higher than before the fast, food intake may thus reach the value during forced-feeding for "foie gras". Since nitrogen assimilation rate also increases 2.5 times, nitrogen fixation is increased 6.8 times, suggesting a high level of protein synthesis.

Oxygen consumption of the chick embryo's respiratory organ, the chorioallantoic membrane.

A new technique based on stopping the chick embryo's blood circulation in the intact egg was used to measure in situ the chorioallantoic (CA) oxygen consumption, MCAO2, from incubation day 12 to 20. Total egg MO2, MTOTO2, and wet and dry masses of embryo and CA were also measured daily. Embryo MO2, MEMBO2, was calculated. Mean MCAO2 decreased from 71 mumol X h-1 (17% of MTOTO2, 24% of MEMBO2) at 12 days to 62 mumol X h-1 (5% of MTOTO2) at 20 days. Dry mass of CA did not change significantly. Water remained at a high level in CA (88-94%), but embryo water decreased from 93% to 82% between days 12 and 20. The fairly high level of MCAO2, more marked at young stages, calls for corrections in respiratory and circulatory embryonic variables derived from MTOTO2, such as CA blood flow, CA diffusive capacity for O2, and CA arterio-venous shunt. Mass specific values and intra-specific allometric relations in bird embryos should be recalculated on the basis of MEMBO2 instead of MTOTO2.

Uric acid and urea in relation to protein catabolism in long-term fasting geese.

Five ganders were subjected to an experimental fast comparable to that which spontaneously occurs during breeding in domestic geese, and during migration and breeding in various wild birds. Plasma uric acid and urea concentrations, and their excretion as a proportion of total nitrogen excretion, were studied in relation to daily change in body mass per unit body mass, mg/mdt. This variable has previously been found to reflect changes in protein catabolism over the three phases of fast: I, dm/mdt and protein utilization both decrease; II, they are maintained at a low value; and III, they increase. In the fed state, daily total nitrogen excretion was 5 gN X 24 h-1; uric acid, ammonia and urea accounted for 51, 15 and 5% respectively. The high remaining proportion of excreted nitrogen (29%), after subtraction of uric acid-N, ammonia-N and urea-N to total nitrogen, accords with the literature. During fasting, the changes in daily excretion of uric acid, urea, ammonia and total nitrogen followed a pattern essentially similar to that for dm/mdt. Uric acid accounted for a progressively increasing fraction of total nitrogen, up to 76% at the end of phase III, while urea remained at a constant 5%. Plasma concentrations of both uric acid and urea followed similar trends during the fast, in particular both increasing during phase III, i.e. when there was a rise in nitrogen excretion. This suggests they could be used as an index in field investigations, to determine whether birds which naturally fast in connection with specific activities have entered into the situation where proteins are no longer spared.

Altitude hypocapnia at 2,800 m does not affect development of the chicken embryo.

Eggs laid at sea level and incubated at high altitude are subject to hypoxia, hypocapnia, and excessive water loss, resulting in retarded development and poor hatchability. The effect of altitude hypocapnia alone was studied in two series of eggs incubated at a simulated altitude of 2,800 m, PB = 542 torr; the incubator was ventilated at a low flow rate with O2-enriched air; the relative humidity was 70-74%, PH2O 34.4-36.4 torr; ambient PO2 about 130 torr at the plateau stage. In the normocapnic series, CO2 produced by the embryos increased ambient PCO2 to 14 torr at 18-19 days; altitude hypoxia, hypocapnia, and excessive water loss were practically compensated for. In the hypocapnic series, ambient CO2 was almost completely absorbed by soda lime, so that only hypocapnia was not compensated for. In 17-19-day eggs with similar sea level mass specific shell conductances [sp GH2O = 0.26-0.25 mg [g.d.torr]-1], the measured PO2 in the gas space, hematocrit, hemoglobin concentration, lengths of beak and third toe, and masses of body and brain were essentially the same in both series. The masses of heart, liver, and left wing were slightly different on day 19. Altitude hypocapnia alone, without altitude hypoxia and excessive water loss, had almost no significant effect on the embryos' development and hatchability.

Ambient temperature and ketone body plasma concentration in fasting geese.

The effect on ketonemia of alternate exposure to ambient temperatures (Ta) of 25 and 5 degrees C was investigated in fasting geese. Three experimental birds were compared to three controls continuously exposed to 25 degrees C Ta while fasting. During the first 9 days of fasting, when both groups were exposed to 25 degrees C, plasma concentration of beta-hydroxybutyrate (beta-OHB) increased similarly in both, from 0.10 +/- 0.02 to 6.62 +/- 0.71 mmol X L-1. It later plateaued at 8-9 mmol X L-1 in the control birds. When the experimental birds were exposed to 5 degrees C Ta between the 9th and 15th day of the fast, it increased further during the first 24 h but thereafter decreased of 57%, from 8.62 +/- 1.56 to 3.73 +/- 1.24 mmol X L-1. This decrease was reversed within the 6 days of return to 25 degrees C Ta. In both groups, plasma acetoacetate (AcAc) concentration remained very low during the fast: 51 +/- 1 mumol X L-1. This reversible cold-induced effect on ketonemia may be used for investigating the possible role of ketone bodies in protein sparing during fasting.

Purification and properties of the endoglucanase C of Clostridium thermocellum produced in Escherichia coli.

The celC gene, which codes for a new endoglucanase of Clostridium thermocellum, termed endoglucanase C, was found to be expressed when cloned in Escherichia coli. The enzyme was purified to electrophoretic homogeneneity from E. coli and its biochemical properties were studied. It differs from the previously studied endoglucanases A and B. In particular, endoglucanase C displays features common to endo- and exoglucanases, since it had a high activity on carboxymethylcellulose and on p-nitrophenyl-beta-D-cellobioside where only the agluconic bond was split. In addition, the enzyme was able to release cellobiose units from G3, G4 and G5 cellodextrins. Endoglucanase C was characterized by Western blot in a culture supernatant from C. thermocellum grown on cellulose, using an antiserum raised against the enzyme produced by E. coli.