Oxygen Exposure Time Research Articles

Can Hypoxic Conditioning Improve Bone Metabolism? A Systematic Review.

Among other functions, hypoxia-inducible factor plays a critical role in bone–vascular coupling and bone formation. Studies have suggested that hypoxic conditioning could be a potential nonpharmacological strategy for treating skeletal diseases. However, there is no clear consensus regarding the bone metabolism response to hypoxia. Therefore, this review aims to examine the impact of different modes of hypoxia conditioning on bone metabolism. The PubMed and Web of Science databases were searched for experimental studies written in English that investigated the effects of modification of ambient oxygen on bone remodelling parameters of healthy organisms. Thirty-nine studies analysed the effect of sustained or cyclic hypoxia exposure on genetic and protein expression and mineralisation capacity of different cell models; three studies carried out in animal models implemented sustained or cyclic hypoxia; ten studies examined the effect of sustained, intermittent or cyclic hypoxia on bone health and hormonal responses in humans. Different modes of hypoxic conditioning may have different impacts on bone metabolism both in vivo and in vitro. Additional research is necessary to establish the optimal cyclical dose of oxygen concentration and exposure time.

Postdepositional aerobic and anaerobic particulate organic matter degradation succession reflected by dinoflagellate cysts: The Madeira Abyssal Plain revisited

We report on the succession of selective degradation of dinoflagellate cyst species that can be considered representative for discrete particulate organic matter (POM) classes of different degradability. The effects of anaerobic and aerobic degradation as well as bioturbation in a natural setting are documented in high resolution by means of palynological and geochemical analyses on Madeira Abyssal Plain A- and F-turbidites. These turbidites are unique as their initial ungraded sediments are affected by a downward penetrating oxydation front.Geochemical analyses document the presence of an active downward penetrating oxidation front in the A turbidite, and a palaeo-oxidation front in the F-turbidite. In this latter turbidite, several zones can be distinguished from top to bottom: an oxidised bioturbated zone, an oxidised but not-bioturbated zone, a visible paleo-oxidation front, and a narrow nitrogenous zone overlying unoxidised sediments.We are the first to report that anaerobic degradation within the nitrogenous zones in both turbidites affects cysts of some heterotrophic dinoflagellates. The cyst species affected (Echinidinium aculeatum, Echinidinium spp., cysts of Protoperidinium monospinum and Brigantedinium spp.) exponentially decrease in this zone that is further characterised by a strong decrease in sulphur content due to sulphide oxidation. Degradation rates are different for each species. These cysts of heterotrophic dinoflagellates consist of a nitrogen-rich glycan in contrast to the cellulosic cysts walls of phototrophic dinoflagellates. Therefore, our observation supports the hypothesis that the quality of organic matter plays an important role in OM degradation in oxygen deficient environments with N-rich OM being more labile than other components in these environments.All heterotrophic species are strongly affected by aerobic degradation with their cyst concentrations exponentially decreasing with increasing oxygen exposure. Degradation rates vary between species and range von highly degradable to slightly degradable. Most strongly affected are cysts of Protoperidinium monospinum, Brigantedinium spp., and Echinidinium spp. Increasingly less affected are: Selenopemphix nephroides, Selenopemphix quanta, other Peridinioids and Echinidinium aculeatum. An effect of aerobic degradation on photosynthetic species could only be observed for Pentapharsodinium dalei. All Impagidinium species appeared to be resistant to aerobic degradation.Despite having analysed only a limited number of samples in the bioturbated zone of the F-turbidite, we have strong indications that the bioturbation can lead to the degradation of POM that is not affected by aerobic degradation alone. The cyst species Spiniferites ramosus, Impagidinium paradoxum, Lingulodinium machaerophorum, Nematosphaeropsis labyrinthus, Spiniferites spp., Impagidinium sphaericum, Spiniferites elongates and Spiniferites mirabilis do not show concentration changes in the non-bioturbated aerobic sediments but their concentrations are considerably decreased in the bioturbated part of the F-turbidite. This supports the hypothesis that bioturbation can increase the degradation of POM by e.g. increasing oxygen exposure time and/or by an alteration of aerobic and anaerobic conditions.We furthermore show that the degradation rates of POM components represented by individual cyst species differ between zones with different redox and biological conditions. This implies that POM degradation reaction rate coefficients are environment dependent. Our observation that dinoflagellate cyst species have different degradation rates ranging from extremely labile to extremely recalcitrant within the individual redox/bioturbation zones supports the hypothesis that cyst walls have a species specific molecular structure. Our results support continuum models of organic matter degradation that assume a continuous distribution of organic matter reactivity.

Impact of family integrated care on infants\u2019 clinical outcomes in two children\u2019s hospitals in China: a pre-post intervention study

BackgroundMost Neonatal Intensive Care Units (NICUs) in China have restricted visiting policies for parents. This also implicates that parents are not involved in the care of their infant. Family Integrated Care (FIC), empowering parents in direct care delivery and decisions, is becoming the standard in NICUs in many countries and can improve quality-of-life and health outcomes of preterm infants. The aim of this study was to evaluate the impact of a FIC intervention on the clinical outcomes of preterm infants with Bronchopulmonary Dysplasia (BPD).MethodsA pre-post intervention study was conducted at NICUs in two Chinese children’s hospitals. Infants with BPD were included: pre-intervention group (n = 134) from December 2015 to September 2016, post-intervention (FIC) group (n = 115) and their parents from October 2016 to June 2017. NICU nurses were trained between July and September 2016 to deliver the FIC intervention, including parent education and support. Parents had to be present and care for their infant minimal three hours a day. The infants’ outcome measures were length-of-stay, breastfeeding, weight gain, respiratory and oxygen support, and parent hospital expenses.ResultsCompared with control group (n = 134), the FIC group (n = 115) had significantly increased breastfeeding rates (83% versus 71%, p = 0.030), breastfeeding time (31 days versus 19 days, p < 0.001), enteral nutrition time (50 days versus 34 days, p < 0.001), weight gain (29 g/day versus 23 g/day, p = 0.002), and significantly lower respiratory support time (16 days versus 25 days, p < 0.001). Oxygen Exposure Time decreased but not significant (39 days versus 41 days p = 0.393). Parents hospital expenses in local Chinese RMB currency was not significant (84 K versus 88 K, p = 0.391).ConclusionThe results of our study suggests that FIC is feasible in two Chinese NICUs and might improve clinical outcomes of preterm infants with BPD. Further research is needed to include all infants admitted to NICUs and should include parent reported outcome measures. Our study may help other NICUs with limited parental access to implement FIC to enhance parental empowerment and involvement in the care of their infant.

Abstract PD-033: A PRE-POST INTERVENTION STUDY TO ASSES THE IMPACT OF FAMILY INTEGRATED CARE ON INFANTS’ CLINICAL OUTCOMES IN TWO CHINESE NEONATAL INTENSIVE CARE UNITS

Aims & Objectives: In China, parents have limited access to Neonatal Intensive Care Units (NICUs) and are not integrated in the care of their preterm infant during hospitalization. Family Integrated Care (FIC) is a model where parents become the primary caretaker to improve quality-of-life and health outcomes of preterm infants. The aim of the study was to evaluate the impact of a FIC intervention on the clinical outcomes of preterm infants with Bronchopulmonary Disease (BPD). Methods A pre-post intervention study at NICUs in two Chines children’s hospitals. The pre-intervention group included infants (n=134) hospitalized from December 2015 to September 2016; FIC group were infants (n=115) admitted between October 2016 to June 2017. NICU nurses were trained, July to September 2016, to deliver the FIC intervention; parent education and support. Parents needed to take care for their infant for minimal three hours a day. Outcome measures were length-of-stay, breastfeeding, weight gain, respiratory and oxygen support. Results Compared with control group (n=134), FIC group (n=115) had significantly higher breastfeeding rate (χ2 = 4.696, p=0.030), breastfeeding time (t = 4.501, p<0.001), enteral nutrition time (t = 7.195, p<0.001), weight gain (t=3.180,p=0.002), and significantly lower respiratory support time (t = -5.388, p<0.001). Oxygen Exposure Time decreased but not significant (39.38 ± 14.918 VS 40.94 ± 13.786; p=0.393) (Table 1).Conclusions Our study suggests that educating and involving parents in the care might improve clinical outcomes of preterm infants with BPD and provides a reference for further implementation of FIC to enhance parental involvement in those NICU with limited parental participation.

The former presence of organic matter caused its later absence: Burn‐down of organic matter in oceanic red beds enhanced by bioturbation (Eocene Variegated Shale, Carpathians)

AbstractEocene oceanic red beds that formed in a well‐oxygenated setting at low sedimentation rates below the calcite compensation depth are effectively barren of organic carbon in the present state. Recurrent distal low‐erosive turbidites preserve the bioturbated zone underneath that documents seasonal and long‐term fluctuating accumulation of considerable amounts of organic matter on the sea floor as evidenced by Scolicia; the producers of this trace fossil exploited nutritious organic matter conserved in turbidite‐buried sea floor deposits. Over the long‐term, slow average sedimentation of (hemi)pelagic oxic (red) mud led to long oxygen exposure times and low burial of organic matter. Consequently, trace fossils representing persistent sediment‐feeding modes are of small size. Although the food‐limited setting appears appropriate for producers of graphoglyptids, such ‘stationary’ burrows have not been encountered because seasonal deposition of organic matter fostered at least temporary surface layer feeding organisms, for instance producers of Nereites irregularis that intensively reworked the sediment and, hence, hindered graphoglyptid production. These findings confirm palaeoceanographic modelling results that suggest upwelling in the study area during the Eocene.

The effects of hypoxia on active ionic transport processes in the gill epithelium of hyperregulating crab, Carcinus maneas

Effects of hypoxia on the osmorespiratory functions of the posterior gills of the shore crab Carcinus maenas acclimated to 12ppt seawater (DSW) were studied. Short-circuit current (Isc) across the hemilamella (one epithelium layer supported by cuticle) was substantially reduced under exposure to 1.6, 2.0, or 2.5mg O2/L hypoxic saline (both sides of epithelium) and fully recovered after reoxygenation. Isc was reduced equally in the epithelium exposed to 1.6mg O2/L on both sides and when the apical side was oxygenated and the basolateral side solely exposed to hypoxia. Under 1.6mg O2/L, at the level of maximum inhibition of Isc, conductance was decreased from 40.0mScm−2 to 34.7mScm−2 and fully recovered after reoxygenation. Isc inhibition under hypoxia and reduced 86Rb+ (K+) fluxes across apically located K+ channels were caused preferentially by reversible inhibition of basolaterally located and ouabain sensitive Na+,K+-ATPase mediated electrogenic transport. Reversible inhibition of Isc is discussed as decline in active transport energy supply down regulating metabolic processes and saving energy during oxygen deprivation.In response to a 4day exposure of Carcinus to 2.0mg O2/L, hemolymph Na+ and Cl− concentration decreased, i.e. hyperosmoregulation was weakened. Variations of the oxygen concentration level and exposure time to hypoxia lead to an increase of the surface of mitochondria per epithelium area and might in part compensate for the decrease in oxygen availability under hypoxic conditions.

The influence of oxygen exposure time on the composition of macromolecular organic matter as revealed by surface sediments on the Murray Ridge (Arabian Sea)

The Arabian Sea represents a prime example of an open ocean extended oxygen minimum zone (OMZ) with low oxygen concentrations (down to less than 2µM) between 200 and 1000m water depth. The OMZ impinges on the ocean floor, affecting organic matter (OM) mineralization. We investigated impact of oxygen depletion on the composition of macromolecular OM (MOM) along a transect through the OMZ on the slopes of the Murray Ridge. This sub-marine high in the northern Arabian Sea, with the top at approximately 500m below sea surface (mbss), intersects the OMZ. We analyzed sediments deposited in the core of OMZ (suboxic conditions), directly below the OMZ (dysoxic conditions) and well below the OMZ (fully oxic conditions). The upper 18cm of sediments from three stations recovered at different depths were studied. MOM was investigated by Rock Eval and flash pyrolysis techniques. The MOM was of a predominant marine origin and inferred from their pyrolysis products, most biomolecules (tetra-alkylpyrrole pigments, polysaccharides, proteins and their transformation products, and polyphenols including phlorotannins), showed a progressive relative degradation with increasing exposure to oxygen. Alkylbenzenes and, in particular, aliphatic macromolecules increased relatively. The observed differences in MOM composition between sediment deposited under various bottom water oxygen conditions (i.e. in terms of concentration and exposure time) was much larger than within sediment cores, implying that early diagenetic alteration of organic matter depends largely on bottom water oxygenation rather than subsequent anaerobic degradation within the sediments, even at longer time scales.

Effect of ocean oxidation on the chemical structure of marine kerogen

The burial of organic matter (OM) in marine sediments is an important control on global climate and petroleum formation on geological timescales. While the oxygen exposure time of sediment has been shown to affect the efficiency of organic carbon burial, and influence OM properties in recent sediments, the implications for the chemical composition of kerogen have not been tested. This study tests the hypothesis that oceanic redox conditions are an important control on the molecular structure and composition of kerogen. Samples from a number of outcropping Late Cretaceous mudstones of the Eagle Ford Formation were chosen, spanning a gradient of paleo-redox depositional conditions (oxic/sub-oxic to anoxic) and the bulk molecular composition of the kerogen was determined using solid state 13C nuclear magnetic resonance (NMR) spectroscopy. The NMR spectral properties of kerogen covaried with redox-sensitive trace metal abundance, whereas the thermal maturity and OM source biomarkers were relatively invariant. Anoxic environments favor the preservation of alkyl C moieties, while kerogen formed in oxic depositional environments was enriched in aromatic C. This study is the first to demonstrate that diagenetic consequences of bottom water redox conditions are retained in the molecular structure of the kerogen macromolecule on geological timescales.

The impact of oxic degradation on long chain alkyl diol distributions in Arabian Sea surface sediments

Oxygen exposure has a large impact on lipid biomarker preservation in surface sediments and may affect the application of organic proxies used for reconstructing past environmental conditions. To determine its effect on long chain alkyl diol and keto-ol based proxies, the distributions of these lipids was studied in nine surface sediments from the Murray Ridge in the Arabian Sea obtained from varying water depths (900–3000m) but in close lateral proximity and, therefore, likely receiving a similar particle flux. Due to substantial differences in bottom water oxygen concentration (<3–77μmol/L) and sedimentation rate, substantial differences exist in the time the biomarker lipids are exposed to oxygen in the sediment. Long chain alkyl diol and keto-ol concentrations in the surface sediments (0–0.5cm) decreased progressively with increasing oxygen exposure time, suggesting increased oxic degradation. The 1,15-keto-ol/diol ratio (DOXI) increased slightly with oxygen exposure time as diols had apparently slightly higher degradation rates than keto-ols. The ratio of 1,14- vs. 1,13- or 1,15-diols, used as upwelling proxies, did not show substantial changes. However, the C30 1,15‐diol exhibited a slightly higher degradation rate than C28 and C30 1,13‐diols, and thus the Long chain Diol Index (LDI), used as sea surface temperature proxy, showed a negative correlation with the maximum residence time in the oxic zone of the sediment, resulting in ca. 2–3.5°C change, when translated to temperature. The UK′37 index did not show significant changes with increasing oxygen exposure. This suggests that oxic degradation may affect temperature reconstructions using the LDI in oxic settings and where oxygen concentrations have varied substantially over time.

Hypoxia Treatment of Callosobruchus maculatus Females and Its Effects on Reproductive Output and Development of Progeny Following Exposure.

Modified atmospheres present a residue-free alternative to fumigants for controlling postharvest pests of grain during storage. How sub-lethal applications of this method affects the reproductive fitness of target pests, however, is still not fully understood. We examined how low levels of ambient oxygen influence the reproduction of the female cowpea bruchid (Callosobruchus maculatus), a pest of cowpea. We used three low-oxygen atmospheres—2%, 5% and 10% (v/v) oxygen—and observed their effects on: (1) the number of eggs laid by bruchids compared to insects held in normoxic (~20% oxygen) conditions; (2) the total number of eggs laid; and (3) the number of progeny that reached maturity. Low oxygen did not significantly affect the number of eggs laid during 48 or 72 h of exposure, but 2% and 5% oxygen did negatively affected total egg production. Increasing the exposure time from 48 to 72 h further depressed lifetime reproductive output. Maternal and egg exposure to hypoxia reduced the number of progeny that reached adulthood. Lower adult emergence was observed from eggs laid under low oxygen and longer exposure times. These data demonstrate that hermetic conditions depress the egg-laying behavior of cowpea bruchids and the successful development of their progeny.

Organic carbon burial efficiency in a subtropical hydroelectric reservoir

Abstract. Hydroelectric reservoirs bury significant amounts of organic carbon (OC) in their sediments. Many reservoirs are characterized by high sedimentation rates, low oxygen concentrations in bottom water and a high share of terrestrially derived OC, and all of these factors have been linked to a high efficiency of OC burial. However, investigations of OC burial efficiency (OCBE, i.e., the ratio between buried and deposited OC) in reservoirs are limited to a few studies, none of which include spatially resolved analyses. In this study we determined the spatial variation in OCBE in a large subtropical reservoir and related it to sediment characteristics. Our results show that the sediment accumulation rate explains up to 92 % of the spatial variability in OCBE, outweighing the effect of other variables, such as OC source and oxygen exposure time. OCBE at the pelagic sites varied from 48 to 86 % (mean 67 %) and decreased towards the dam. At the margins, OCBE was lower (9–17 %) due to the low sediment accumulation in shallow areas. Our data show that the variability in OCBE both along the rivers–dam and the margin–pelagic axes must be considered in whole-reservoir assessments. Combining these results with a spatially resolved assessment of sediment accumulation and OC burial in the studied reservoir, we estimated a spatially resolved mean OC burial efficiency of 57 %. Being the first assessment of OCBE with such a high spatial resolution in a reservoir, these results suggest that reservoirs may bury OC more efficiently than natural lakes.

Effect of glow discharge oxygen plasma treated surface and antimicrobial properties of viscose fabric

In this paper, an effective and clean production process was developed for spandex mixed viscose fabric pretreatment with the aid of low pressure plasma. The functional properties are developed due to plasma treatment. The influence of plasma parameters, such as oxygen pressure, discharge power and exposure time of pretreatment, on the fabric was investigated and compared with aloe vera and ZnO coated fabric. Results reveal the weight loss, impurity removal, contact angle and antimicrobial properties of the fabric. Modification of the chemical nature of the fabric surface was characterised by ATR-FTIR, the study of the surface morphology by scanning electron microscopy.

A simple and controllable method for reproduction of a model of high oxygen tension induced acute lung injury

To explore a simpler, more economic and reproducible method to reproduce a model of high oxygen induced acute lung injury (HALI) in rats. An animal feeding box equipped with a controllable high oxygen was designed. 100 Sprague-Dawley (SD) rats were divided into normal control group and HALI group by random number table method, with 50 rats in each group. Each group was randomly subdivided into five subgroups according to the duration of exposure to high oxygen, namely 0, 24, 48, 72 and 96-hour subgroups, with 10 rats in each subgroup. The rats in normal control group were kept in cages with ambient air, and the rats in HALI group were kept in an oxygen tank in which the oxygen concentration was higher than 90% volume ratio, with the temperature maintained at 25-27?centigrade, humidity of 50%-70%, and CO2 concentration < 0.5% for 23.5 hours every day. The arterial blood of rats was collected for analysis of blood gas at all time points, and the oxygenation index (OI) and respiratory index (RI) were calculated. Then the rats were sacrificed and the right lung was harvested, which was sectioned and stained with hematoxylin and eosin (HE). The changes in histopathology were observed with light microscopy, and pathological score was recorded. The left lung was harvested for the measurement of the wet/dry weight ratio (W/D). With the prolongation of high oxygen exposure time, the degree of lung injury in HALI group was gradually increased, and the degree of derangement of alveolar structure appeared in an increasing degree, with destruction of the alveolar wall, widening of alveolar space, and appearance of edema, and inflammatory cell infiltration. A small quantity of red blood cells exudation could be found in some rats. The pathologic changes were most obvious at 48-72 hours after exposure. With the prolongation of high oxygen exposure time (0, 24, 48, 72, 96 hours), the OI (mmHg, 1 mmHg = 0.133 kPa) in HALI group was gradually decreased (446.67±29.93, 306.19±37.23, 269.70±29.00, 253.81±43.40 and 245.58±35.25), RI, pathological score of lung tissue and W/D ratio were gradually increased [RI: 0.25±0.04, 0.31±0.06, 0.38±0.06, 0.46±0.07 and 0.44±0.03; pathological score of lung tissue: 0.00±0.00, 0.90±0.74, 2.90±1.20, 4.70±1.57 and 4.80±1.23; lung W/D ratio: 3.84±0.61, 4.14±0.46, 4.56±0.34, 5.32±0.27 and 5.18±0.25]. Statistically significant differences were found in 72-hour group as compared with that of other groups (all P < 0.05), while no significant difference was found between 96 hours and 72 hours groups (all P > 0.05). There were significant differences in changes between 24, 48, 72, and 96 hours as compared with those of the normal control group: OI (mmHg): 24 h 306.19±37.23 vs. 435.65±25.34 and 96 h 245.58±35.25 vs. 465.42±24.75; RI: 24 h 0.31±0.06 vs. 0.24±0.04 and 96 h 0.44±0.03 vs. 0.24±0.06. The same as true in pathological scores of lung tissue: 24 h 0.90±0.74 vs. 0.00±0.00 and 96 h 4.80±1.23 vs. 0.00±0.00; lung W/D ratio: 24 h 4.14±0.46 vs. 3.79±0.44 and 96 h 5.18±0.25 vs. 4.12±0.91, all P < 0.05. A self-designed high oxygen box is simple, easy to operate and reproduction of HALI model can be attained. Sustained exposure to high concentrations of oxygen (≥ 90%) for 24 hours can replicate the HALI model successfully, and the most serious injury appears at 48-72 hours after exposure.

Manipulation of Conditions during Wort Collection in Production-Scale Fermentations to Regulate Volatile Ester Synthesis as an Aid to Product Matching for Multisite Brewing

Volatile esters are amongst the most important yeast-derived flavor-active compounds produced during brewery fermentation. Dissolved oxygen concentration has long been recognized as an effector for the synthesis of esters by Saccharomyces spp. Here we demonstrate the effects of oxygen exposure time at vessel filling on the synthesis of esters during fermentation using a series of laboratory-scale experiments. In control fermentations, all the yeast was pitched into 10 L of high-gravity wort. In trial fermentations, all the yeast was pitched at the start of collection and wort was added as three 3.33-L batches or five 2-L batches over 12 or 24 hr, respectively. Wort was oxygenated to 15 ppm of O2 for each experiment and identical pitching rates and temperature profiles were adopted. Compared with the controls, increasing the number of batch fills to three and five reduced the final concentration of isoamyl acetate by 15.7 and 34%, respectively, and ethyl acetate by 25 and 39%, respectively, suggesting that a relationship exists between oxygen exposure time and ester synthesis. In parallel, hydrostatic pressure was applied to each condition, resulting in a further decrease in acetate esters. These data suggest that an inverse correlation exists between vessel size relative to brew length and ester production.

Temperature, oxygen, and vegetation controls on decomposition in a James Bay peatland

AbstractThe biochemical composition of a peat core from James Bay Lowland, Canada, was used to assess the extent of peat decomposition and diagenetic alteration. Our goal was to identify environmental controls on peat decomposition, particularly its sensitivity to naturally occurring changes in temperature, oxygen exposure time, and vegetation. All three varied substantially during the last 7000 years, providing a natural experiment for evaluating their effects on decomposition. The bottom 50 cm of the core formed during the Holocene Climatic Optimum (~7000–4000 years B.P.), when mean annual air temperature was likely 1–2°C warmer than present. A reconstruction of the water table level using testate amoebae indicated oxygen exposure time was highest in the subsequent upper portion of the core between 150 and 225 cm depth (from ~2560 to 4210 years B.P.) and the plant community shifted from mostly Sphagnum to vascular plant dominance. Several independent biochemical indices indicated that decomposition was greatest in this interval. Hydrolysable amino acid yields, hydroxyproline yields, and acid:aldehyde ratios of syringyl lignin phenols were higher, while hydrolysable neutral sugar yields and carbon:nitrogen ratios were lower in this zone of both vascular plant vegetation and elevated oxygen exposure time. Thus, peat formed during the Holocene Climatic Optimum did not appear to be more extensively decomposed than peat formed during subsequent cooler periods. Comparison with a core from the West Siberian Lowland, Russia, indicates that oxygen exposure time and vegetation are both important controls on decomposition, while temperature appears to be of secondary importance. The low apparent sensitivity of decomposition to temperature is consistent with recent observations of a positive correlation between peat accumulation rates and mean annual temperature, suggesting that contemporary warming could enhance peatland carbon sequestration, although this could be offset by an increasing contribution of vascular plants to the vegetation.

EVALUATION OF CHOROIDAL THICKNESS AND RETINAL PIGMENTED EPITHELIUM USING CIRRUS SD-OCT IN PORTUGUESE CHILDREN WITH HISTORY OF PRETERM BIRTH

Purpose: To determine choroidal thickness in preterm children with and without history of Retinopathy of Prematurity using spectral domain optical coherence tomography (SD-OCT) system. Methods: In a cross-sectional study, 39 eyes of premature patients (Group 1) and 39 eyes with history of ROP (Group 2) between 9 and 17 years old were evaluated with Cirrus Zeiss 500 SD-OCT after cycloplegia. Choroidal thickness was measured from the fovea to 1500µm nasal- and temporally with intervals of 500 µm using HD1 line raster program of SD-OCT. Clinical history such as gestational age at birth, birth weight, time of oxygen exposure, Stage of ROP in maximal severity of acute disease, ROP treatment were questioned. Results: Subfoveal thickness was lower in Group 2 ( 296,85±60,11µm) than in Group 1 (301,82±30,63µm). The mean choroidal thickness in all retinal tested points weren’t statistically different between the 2 groups. The time of oxygen exposure was the most relevant negative predictor considering choroidal thickness (s=-0,420; p= 0,032). Conclusions: Choroidal thickness can be measured using SD-OCT high definition raster scans in the majority of children eyes. Choroidal thickness across the macula of children with and without ROP is thinner nasally, sub-foveal and temporally in the second group, however without statistical difference. This can suggest a delayed development of choroid in preterm infant due to ROP, which can be attenuated with age.

Tunable near-infrared localized surface plasmon resonances of djurleite nanocrystals: effects of size, shape, surface-ligands and oxygen exposure time

The effects of size, shape, surface ligands and oxygen exposure time on the localized surface plasmon resonance absorption in monoclinic djurleite nanocrystals have been demonstrated.

Effect of low-temperature oxygen plasma on the degumming of ramie fabric

Ramie fiber is one of the most important materials for textile manufacturing. However, the conventional degumming processes for ramie involve numerous chemicals and water consumptions, resulting in a serious environmental concern. The purpose of this work is to investigate the effect of low-temperature oxygen plasma (LTP-O2) treatment on ramie fabric degumming in combination with a subsequent mild wet chemical process. The oxygen plasma treatment variables such as oxygen gas pressure, discharge power and exposure time were investigated and optimized according to the indexes of fabric total impurity removal, whiteness, capillary rise height, tensile strength and elongation, etc. The results show that a notable effect of oxygen plasma on ramie degumming was observed in a subsequent mild wet chemical process. The fabric capillary rise height, whiteness, tensile strength and elongation of the pretreated ramie were improved with gas pressures from 20 Pa to 40 Pa, although accompying with a decrease tendency in impurity removal, as well as for the capillary rise height as pressures higher than 40 Pa. Furthermore, the fabric impurity removal, capillary rise height were enhanced with plasma discharge power from 30.0 W to 250.0 W, with less affects on fabric whiteness, tensile strength and elongation. Moreover, most of the degumming indexes were also improved as the exposure time from 1.0 min to 3.0 min, except for a worse deterioration of fabric tensile strength as an exposure time longer than 5.0 min. An optimized plasma process for ramie fabric degumming was at 40.0 Pa of oxygen gas and 250.0 W of glow discharge for 3.0 min. In comparison with a control and conventional degumming processes, higher degumming effects and mechanical properties of ramie fabric were achieved by the combination degumming process with more environmentally friendly due to less consumption of chemicals, water and energy. Moreover, the effect of oxygen plasma on ramie fiber was further confirmed and characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM).

Efficacy of caffeine combined with non-invasive respiratory support on the treatment of apnea in very low birth weight preterm infants

Objective To compare the efficacy and safety of caffeine combined with humidified high-flow nasal cannula (HHHFNC) and nasal continuous positive airway pressure (nCPAP) on the treatment of apnea in very low birth weight (VLBW) preterm infants. Methods Totally 80 VLBW preterm infants with neonatal apnea, who were enrolled in the NICU of Hebei Province Children Hospital from September 2013 to March 2014, were randomly assigned to either HHHFNC group (39 cases) or nCPAP group (41 cases) according to respiratory support mode by random number table method, both groups were given caffeine. The incidence of severe apnea, incidence of reintubation, oxygen exposure time, duration of non-invasive ventilation time, feeding conditions and incidence of adverse events were compared. Results There were no significant differences in male/female ratio, gestational age, age at randomization and birth weight between the two groups (P>0.05). There were no significant differences in the incidence of severe apnea[15.4% (6/39) vs 12.2% (5/41)], incidence of reintubation[17.9% (7/39) vs 19.5% (8/41)], oxygen exposure time [(183.1±31.2) h vs (175.9±32.1) h], duration of non-invasive ventilation time [(163.3±25.1) h vs (153.0±26.2) h] between the two groups (P>0.05). The occurrence of abdominal distention[7.7% (3/39) vs 24.4% (10/41)], nasal trauma[2.6% (1/39) vs 19.5% (8/41)], head shaping[0.0% (0/39) vs 29.3% (12/41)] during treatment were lower in HHHFNC group than those of nCPAP group (P<0.05). Age began feeding was earlier in HHHFNC group than nCPAP group [(67.5±19.1) h vs (96.3±18.7) h, P<0.05], and day to full oral feeding was reduced in HHHFNC group than nCPAP group [(346.8±28.6) h vs (371.0±29.4), P<0.05]. Conclusion HHHFNC combined with caffeine is effective on the treatment of apnea in VLBW preterm infants, and easier to make newborn tolerated. HHHFNC is an effective non-invasive respiratory support mode with few side effects. Key words: Very low birth weight preterm infants; Heated humidified high-flow nasal cannula; Nasal continuous positive airway pressure; Apnea; Caffeine

Low organic carbon burial efficiency in arctic lake sediments

AbstractMany arctic landscapes are rich in lakes that store large quantities of organic carbon in their sediments. While there are indications of highly efficient carbon burial in high‐latitude lakes, the magnitude and efficiency of carbon burial in arctic lake sediments, and thus their potential as carbon sinks, has not been studied systematically. We therefore investigated the burial efficiency of organic carbon (OC), defined as the ratio between OC burial and OC deposition onto the sediment, in seven contrasting lakes in western Greenland representing different arctic lake types. We found that the OC burial efficiency was generally low in spite of the differences between lake types (mean 22%, range 11–32%), and comparable to lakes in other climates with similar organic matter source and oxygen exposure time. Accordingly, post‐depositional degradation of sediment organic matter was evident in the organic matter C:N ratio, δ13C and δ15N values during the initial ~50 years after deposition, and proceeds simultaneously with long‐term changes in, e.g., productivity and climate. Pore water profiles of dissolved methane suggest that post‐depositional degradation may continue for several centuries in these lakes, at very low rates. Our results demonstrate that the regulation of the sediment OC burial efficiency is no different in arctic lakes than in other lakes, implying that the efficiency of the carbon sink in lake sediments depends similarly on environmental conditions irrespective of latitude.