PN Concentrations Research Articles

An alternative approach for daily perineal care of patients with indwelling urinary catheterization: Photodynamic inactivation with cationic porphyrin derivatives

Background: Catheter-associated urinary tract infections (CAUTI) constitute a significant portion of healthcare-associated infections. Using antiseptic for routine daily perineal care of patients with IUC may reduce CAUTIs. Aim: This study aimed to examine antimicrobial photodynamic inactivation (aPDI) against clinical isolates for use in the daily perineal care of patients with IUC. In addition, it was also aimed to compare the antimicrobial activities of aPDI and 0.1% chlorhexidine gluconate. Methods: In this in-vitro study, cationic porphyrin derivatives (CPDs) were used as photosensitizers in the experiments. CPDs, named PM, PE, PN, and PL were synthesized by the researchers. A diode laser device emitting light with a wavelength of 450 nm (blue light) was used as the light source. Methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli and Klebsiella pneumoniae with multidrug-resistant (MDR) properties and Candida albicans were used. Photosensitizer (PS), aPDI, light (L), and control (C) groups in aPDI experiments; control (C) and chlorhexidine gluconate 0.1% groups were used in the chlorhexidine gluconate experiments. Survival was calculated based on CFU/mL in the control group. Results: In experiments, combinations of 25 J/cm² with 6.25 and 3.125 µM PM, PE reduced E. coli, K. pneumoniae, MRSA, and C. albicans survival in the range of 8.70 to 11.53 log₁₀. In aPDI experiments performed with 6.25 and 3.125 µM PN and PL concentrations at the same energy density, reductions in the range of 4.41 to 0.17 log₁₀ were observed in all four clinical isolates. In experiments where 1.5625 µM concentration was used, survival decreased in the range of 8.29 to 10.87 log₁₀ in PM and PE, while antimicrobial activity was limited in PN and PL. In the 0.1% chlorhexidine gluconate experiments, the survival reduction in all four clinical isolates ranged from 8.87 to 10.24 log₁₀. Conclusion: For PM and PE, a very strong aPDI was obtained in C. albicans, E.coli, K. pneumoniae, and MRSA at low concentrations and energy density. The same antimicrobial activity was found in experiments using 0.1% chlorhexidine gluconate. In this context, we would like to inform you that aPDI to be performed with a combination of 25 J/cm² at 6.25 and 3.125 µM concentrations of PM and PE has the potential to be an antiseptic in the daily perineal care of patients with IUC.

Phenomenology of ultrafine particle concentrations and size distribution across urban Europe

The 2017–2019 hourly particle number size distributions (PNSD) from 26 sites in Europe and 1 in the US were evaluated focusing on 16 urban background (UB) and 6 traffic (TR) sites in the framework of Research Infrastructures services reinforcing air quality monitoring capacities in European URBAN & industrial areaS (RI-URBANS) project. The main objective was to describe the phenomenology of urban ultrafine particles (UFP) in Europe with a significant air quality focus.The varying lower size detection limits made it difficult to compare PN concentrations (PNC), particularly PN10-25, from different cities. PNCs follow a TR > UB > Suburban (SUB) order. PNC and Black Carbon (BC) progressively increase from Northern Europe to Southern Europe and from Western to Eastern Europe. At the UB sites, typical traffic rush hour PNC peaks are evident, many also showing midday-morning PNC peaks anti-correlated with BC. These peaks result from increased PN10-25, suggesting significant PNC contributions from nucleation, fumigation and shipping.Site types to be identified by daily and seasonal PNC and BC patterns are: (i) PNC mainly driven by traffic emissions, with marked correlations with BC on different time scales; (ii) marked midday/morning PNC peaks and a seasonal anti-correlation with PNC/BC; (iii) both traffic peaks and midday peaks without marked seasonal patterns. Groups (ii) and (iii) included cities with high insolation.PNC, especially PN25-800, was positively correlated with BC, NO2, CO and PM for several sites. The variable correlation of PNSD with different urban pollutants demonstrates that these do not reflect the variability of UFP in urban environments. Specific monitoring of PNSD is needed if nanoparticles and their associated health impacts are to be assessed. Implementation of the CEN-ACTRIS recommendations for PNSD measurements would provide comparable measurements, and measurements of <10 nm PNC are needed for full evaluation of the health effects of this size fraction.

Assessment of gaseous, particulate, and unregulated emissions from diesel compression ignition and LPG direct injection spark ignition minibus vehicles under the world harmonized vehicle cycle on a chassis dynamometer

Construction of harmful emission inventory from conventional and sustainable low carbon fueled vehicles is important issues to improve urban air quality and human health. In this study, the gaseous, nanoparticle, and unregulated gaseous emission formation behavior from a medium-duty minibus were investigated using the World Harmonized Vehicle Cycle (WHVC). The state-of-the-art diesel and turbocharged direct-injection liquefied petroleum gas (LPG) vehicle were tested on a chassis dynamometer. The after-treatment system of the 3.9-L diesel engine was composed of the DOC, DPF and SCR, which satisfy the Euro 6 emission regulation. The 3.3-L stoichiometric spark ignition direct injection LPG engine was a TWC-only system. The formation of harmful emission components from the light-duty minibus operation was closely related to powertrain types, combustion mechanisms, after-treatment devices, and physicochemical properties of the tested fuels. Additionally, the chemical composition and low heating value (or energy content) of the respective fuels substantially affected the vehicle CO2 emissions and fuel economy performance. Compared to LPG vehicle, the THC and NOx emissions from diesel vehicle were 63% and 511%. Similar PN concentrations were measured with each powertrain, but 2–3 times higher nucleation mode particles were released with diesel vehicle. Two vehicles showed comparable CO2 emissions, while fuel economy from diesel and LPG vehicle were 6.81 km/L and 4.60 km/L. The proportions of N2O and CH4 emissions with ozone forming potential (OFP) were 1.2% (diesel) and 0.3% (LPG), which showed the potential to mitigate the CO2-equivalent emissions from LPG minibus.

Exhaust non-volatile particle filtration characteristics of three-way catalyst and influencing factors in a gasoline direct injection engine compared to gasoline particulate filter

Three-way catalyst (TWC) integrated gasoline particulate filter (GPF) has become a standard configuration for the aftertreatment of a gasoline direct injection (GDI) engine. Although filtration effects on particulate emissions of GPFs have been widely investigated, effects of TWCs on non-volatile particulate emissions are still ambiguous. In the present work, particle size distributions were measured by DMS500 with hot sampling at three locations: before TWC, after TWC and after GPF. The particle filtration characteristics of the TWC and GPF are compared, and the influencing factors and filtration mechanism are analyzed. The results show that the TWC have obvious filtration effects on exhaust particles, and the total filtration efficiency is 20–35% for the TWC compared to 70–85% for the GPF. The TWC exhibits high efficiency in the small and large particle size ends, indicating the particle collection process in the TWC may resemble the collection process in the GPF. Regarding the influencing factors, the filtration efficiency of the TWC is related to both the exhaust temperature and exhaust flow rate, while that of the GPF mainly depends on the exhaust flow rate. With high engine-out PN concentrations, the filtration efficiency of the TWC on AM particles largely decreases, while the filtration efficiency of the GPF on AM particles increases to >95%. It is believed that in TWCs firstly the small particles are collected by diffusion and the large particles by inertia or gravity collection on the washcoat, and then the collected particles get oxidized with the help of the catalyst.

Bus commuter exposure and the impact of switching from diesel to biodiesel for routes of complex urban geometry

We report on commuters’ exposure to black carbon (BC), PM2.5 and particle number (PN, with aerodynamic diameter, da, in the range 0.01 <da< 1.0 μm) collected on-board diesel- and biodiesel-fuelled buses of the Bus Rapid Transit (BRT) system of the city of Curitiba, Brazil. Particulate concentrations measured at high sampling rates allowed the capture of fine gradients along the route and the comparison of in-cabin air pollution on buses of different technologies.Of all metrics, BC showed the largest discrepancies, with mean concentrations of 20.1 ± 20.0 μg m−3 and 3.9 ± 26.0 μg m−3 on diesel- and biodiesel-fuelled buses, respectively. Mean PM2.5 concentrations were similar (31.6 ± 28.5 μg m−3 and 29.0 ± 17.8 μg m−3), whilst mean PN concentrations were larger on the biodiesel buses (56,697 ± 26,800 # cm−3vs. 43,322 ± 32,243 # cm−3). The results are in line with studies on biodiesel emission factors that reported lower BC mass but more particles with smaller diameters. Our hypothesis is that different emission factors of diesel and biodiesel engines reflected in differences of in-cabin particulate concentrations. We found that the passenger exposure during the bus commutes was affected not only by the fuel used but also by the street geometry along the route, with segments with canyon configurations resulting in peak exposure to particulates. The results suggest that i) switching from diesel to biodiesel may help abate commuters’ exposure to BC particles on-board buses of the BRT system, whilst it would need to be complemented with after-treatment technologies to reduce emissions; ii) further reductions in exposure (to peaks in particular) could be achieved by changing bus routes to ones that avoid passing through narrow urban street canyons.

Integration of air pollution data collected by mobile measurement to derive a preliminary spatiotemporal air pollution profile from two neighboring German-Czech border villages

Generally, there are only a few fixed air quality monitoring stations installed in villages or rural areas and only a few studies on small-scale variations in air pollution have been described in detail, which make it difficult to estimate human exposure in such environments and related adverse health effects. Moreover, biomass combustion can be an important source of air pollution in rural areas, comparable to vehicle and industrial emissions in urban planning. And their air pollutants are mainly affected by local sources. For this reason, a survey on rural air pollution was carried out in this study. Therefore, portable, battery-powered monitoring devices were used to measure particulate matter (PM10, PM2.5, PM1, particle number concentration, and black carbon) in order to study air quality in rural communities. The focus of the investigations was to explore the application of mobile monitoring equipment in small-scale environments, compare the differences in rural air pollutants between two neighboring villages in two countries, and the identification of pollution hotspots. The measurements were carried out in November 2018 in two villages on the German-Czech border. Over a period of four days, 21 mobile measurements along fixed routes were carried out simultaneously at both locations. The analysis of the data revealed significant differences in PN and PM concentrations in rural air pollutants between the two countries. The spatial and temporal distribution of air pollution hotspots in the Czech village was higher than that in the German village. The relationships between the measurement parameters were weak but highly significant and the meteorological parameters can effect air pollution. Overall, the results of this study show that mobile measurements are suitable for effectively recording and distinguishing spatial and temporal characteristics of air quality.

On the seasonal aerosol pollution levels and its sources in some primary schools in Vilnius, Lithuania.

Aerosol particle number (PNC) and mass concentrations (PMC) were studied in 11 primary schools during the 2017-2018 school years (from September to May) in Vilnius, Lithuania, with the aim to evaluate the main aerosol pollution sources and its levels. Expeditious information on the total aerosol particle concentration over the full range of sizes (from 0.01 to > 1μm) was estimated using a condensation particle counter (CPC). Particle number and mass concentrations in the size range of 0.3-10μm were measured and estimated using an optical particle sizer (OPS). The use of aerosol particle size spectra (OPS) in school lodgements facilitated the identification of the main sources of indoor air pollution. The main sources responsible for the elevated levels of indoor PN and PM aerosol concentrations were determined: local canteens in the absence of ventilation (particle concentrations up to 97,500 part/cm3 (CPC)), the school-grader activity during the lesson breaks (275-586μg/m3), soft furniture and carpets in the classrooms and corridors (~ 200μg/m3), and in some cases (city center) elevated outdoor aerosol pollution levels (16800-18,170 part/cm3). Elevated aerosol pollution levels were also due to the occasional sources: construction works during lessons (200-1000μg/m3), scraping the exterior walls of buildings near schools (up to 1600μg/m3), and the use of petrol-powered trimmers during cutting of green plantings (22500-66,400 part/cm3 (CPC)).

Potential to reduce the concentrations of short-lived climate pollutants in traffic environments: A case study in a medium-sized city in Brazil

Understanding the spatio-temporal variation of short lived climate pollutants (SLCP) over cities is critical to protect public health and mitigate climate change. There is a lack of knowledge about the distribution of SLCP in South America, mainly in medium-sized cities (<1 million inhabitants). This work reports on results of a campaign conducted at several sites (street canyon, urban background, and suburban) in Londrina, Brazil. The pollution datasets (black carbon BC, nitrogen oxides NOx, ozone O3, fine particles PM2.5, and particle number PN) were analyzed by using descriptive statistics, diurnal cycles, time-space correlations, and establishing linkages with traffic rates and with wind conditions. Hourly mean (±standard deviation) BC concentrations ranged from 0.58 (±0.54) in the suburban area to 3.43 (±2.69) µg m−3 at the street canyon site (10,150 vehicles d−1 on weekdays), showing a high spatio-temporal variability even at short scales. PN (mean of 17,469 cm−3) and NOx (mean of 51.58 µg m−3) concentrations tracked BC levels and traffic rates, particularly the number of diesel buses at the canyon site. PM2.5 and O3 levels presented a lower spatial variability, with poor correlation with traffic rates in the canyon and were more tied to regional sources. NOx, BC, and PN showed the highest reduction potentials connected to the abatement of traffic emissions in the city center, particularly by targeting heavy-duty diesel vehicles. The reduction of PM2.5 and O3 concentrations is more challenging due to a significant regional contribution that requires cutting down emissions at state, national or even transboundary scales.

Short-term effects of airport-associated ultrafine particle exposure on lung function and inflammation in adults with asthma

BackgroundExposure to ultrafine particles (UFP, particles with aerodynamic diameter < 100 nm) is associated with reduced lung function and airway inflammation in individuals with asthma. Recently, elevated UFP number concentrations (PN) from aircraft landing and takeoff activity were identified downwind of the Los Angeles International Airport (LAX) but little is known about the health impacts of airport-related UFP exposure. MethodsWe conducted a randomized crossover study of 22 non-smoking adults with mild to moderate asthma in Nov-Dec 2014 and May-Jul 2015 to investigate short-term effects of exposure to LAX airport-related UFPs. Participants conducted scripted, mild walking activity on two occasions in public parks inside (exposure) and outside (control) of the high UFP zone. Spirometry, multiple flow exhaled nitric oxide, and circulating inflammatory cytokines were measured before and after exposure. Personal UFP PN and lung deposited surface area (LDSA) and stationary UFP PN, black carbon (BC), particle-bound PAHs (PB-PAH), ozone (O3), carbon dioxide (CO2) and particulate matter (PM2.5) mass were measured. Source apportionment analysis was conducted to distinguish aircraft from roadway traffic related UFP sources. Health models investigated within-subject changes in outcomes as a function of pollutants and source factors. ResultsA high two-hour walking period average contrast of ~34,000 particles·cm−3 was achieved with mean (std) PN concentrations of 53,342 (25,529) and 19,557 (11,131) particles·cm−3 and mean (std) particle size of 28.7 (9.5) and 33.2 (11.5) at the exposure and control site, respectively. Principal components analysis differentiated airport UFPs (PN), roadway traffic (BC, PB-PAH), PM mass (PM2.5, PM10), and secondary photochemistry (O3) sources. A standard deviation increase in the ‘Airport UFPs’ factor was significantly associated with IL-6, a circulating marker of inflammation (single-pollutant model: 0.21, 95% CI = 0.08–0.34; multi-pollutant model: 0.18, 0.04–0.32). The ‘Traffic’ factor was significantly associated with lower Forced Expiratory Volume in 1 s (FEV1) (single-pollutant model: −1.52, −2.28 to −0.77) and elevated sTNFrII (single-pollutant model: 36.47; 6.03–66.91; multi-pollutant model: 64.38; 6.30–122.46). No consistent associations were observed with exhaled nitric oxide. ConclusionsTo our knowledge, our study is the first to demonstrate increased acute systemic inflammation following exposure to airport-related UFPs. Health effects associated with roadway traffic exposure were distinct. This study emphasizes the importance of multi-pollutant measurements and modeling techniques to disentangle sources of UFPs contributing to the complex urban air pollution mixture and to evaluate population health risks.

Riverine input of organic carbon and nitrogen in water-sediment system from the Yellow River estuary reach to the coastal zone of Bohai Sea, China

The temporal-spatial distribution of the carbon and nitrogen contents and their isotopic compositions of suspended matter and sediments from the Yellow River estuary reach (YRER), the estuary to the offshore area were measured to identify the source of organic matter. The higher relative abundances of suspended and sedimentary carbon and nitrogen (POC, TOC, PN and TN) in the offshore marine area compared to those of the riverine and estuarine areas may be due to the cumulative and biological activity impact. The organic matter in surface sediments of YRER, the estuary and offshore area of Bohai Sea is basically the mixture of continental derived material and marine material. The values of δ13Csed fluctuate from values indicative of a land source (− 22.50‰ ± 0.31) to those indicative of a sea source (− 22.80‰ ± 0.38), which can be attributed to the fine particle size and decrease in terrigenous inputs to the offshore marine area. Contrary to the slight increase of POC and PN during the dry season, TOC and TN contents of the surface sediments during the flood season (October) were higher than those during the dry season (April). The seasonal differences in water discharge and suspended sediment discharge of the Yellow River Estuary may result in seasonal variability in TOC, POC, TN and PN concentrations in some degree. Overall, the surface sediments in the offshore area of Bohai Sea are dominated by marine derived organic carbon, which on average, accounts for 58–82% of TOC when a two end-member mixing model is applied to the isotopic data.

Freeze\u2013thaw processes and intense rainfall: the one-two punch for high sediment and nutrient loads from mid-Atlantic watersheds

Large runoff, sediment, and nutrient exports from watersheds could occur due to individual extreme climate events or a combination of multiple hydrologic and meteorological conditions. Using high-frequency hydrologic, sediment, and turbidity data we show that freeze–thaw episodes followed by intense winter (February) rainstorms can export very high concentrations and loads of suspended sediment and particulate organic carbon (POC) and nitrogen (PN) from mid-Atlantic watersheds in the US. Peak suspended sediment (> 5000 mg L−1), POC (> 250 mg L−1) and PN (> 15 mg L−1) concentrations at our 12 and 79 ha forested watersheds for the February rainfall-runoff events were highest on record and the fluxes were comparable to those measured for tropical storms. Similar responses were observed for turbidity values (> 400 FNU) at larger USGS-monitored watersheds. Much of the sediments and particulate nutrients likely originated from erosion of stream bank sediments and/or channel storage. Currently, there is considerable uncertainty about the contribution of these sources to nonpoint source pollution, particularly, in watersheds with large legacy sediment deposits. Future climate projections indicate increased intensification of storm events and increased variability of winter temperatures. Freeze–thaw cycles coupled with winter rain events could increase erosion and transport of streambank sediments with detrimental consequences for water quality and health of downstream aquatic ecosystems.

Impact of biomass burning emission on total peroxy nitrates: fire plume identification during the BORTAS campaign

Abstract. Total peroxy nitrate ( ∑ PN) concentrations have been measured using a thermal dissociation laser-induced fluorescence (TD-LIF) instrument during the BORTAS campaign, which focused on the impact of boreal biomass burning (BB) emissions on air quality in the Northern Hemisphere. The strong correlation observed between the ∑ PN concentrations and those of carbon monoxide (CO), a well-known pyrogenic tracer, suggests the possible use of the ∑ PN concentrations as marker of the BB plumes. Two methods for the identification of BB plumes have been applied: (1) ∑ PN concentrations higher than 6 times the standard deviation above the background and (2) ∑ PN concentrations higher than the 99th percentile of the ∑ PNs measured during a background flight (B625); then we compared the percentage of BB plume selected using these methods with the percentage evaluated, applying the approaches usually used in literature. Moreover, adding the pressure threshold ( ∼ 750 hPa) as ancillary parameter to ∑ PNs, hydrogen cyanide (HCN) and CO, the BB plume identification is improved. A recurrent artificial neural network (ANN) model was adapted to simulate the concentrations of ∑ PNs and HCN, including nitrogen oxide (NO), acetonitrile (CH3CN), CO, ozone (O3) and atmospheric pressure as input parameters, to verify the specific role of these input data to better identify BB plumes.

Purine Nucleotides Similarly Regulate Uncoupling Protein 3 and 1

ATP generation is fueled by an electrical potential across the inner mitochondrial membrane (IMM), which can be decreased by an uncoupling protein (UCP) facilitated proton leak. Apart from UCP1, which supports non-shivering thermogenesis, the function of the other UCPs, such as UCP3, remains unknown. In contrast to UCP1, few results on UCP3 regulation from studies on isolated mitochondria or liposomes imply that ADP/GDP has a stronger inhibitory effect on UCP3 than ATP/GTP. In light of the fact that both, UCP1 and UCP3 were found in brown adipose tissue, we now test whether UCP3 and UCP1 are regulated differently. For this we compare the inhibition of UCP1 and UCP3 by PNs of varying phosphorylation and concentration, using a system of planar bilayers reconstituted with recombinant protein and FAs (1). In contrast to liposomes, this enables us to directly apply the membrane potential necessary for UCP3 function under physiological conditions. These results show that ATP and not ADP is the most potent UCP3 inhibitor and this is likewise similar to UCP1 and UCP2 (2, 3). UCP3 conductance is more strongly inhibited by the same PN concentrations than is UCP1 conductance, and adenosine nucleotides are more effective inhibitors than guanosines. Our results demonstrate that inhibition of UCP3 is similar to that of UCP1. We anticipate these findings as a starting point to examine whether different factors (in comparison to UCP1) are required to activate UCP3.(1) Beck et al. (2006) Biochim Biophys Acta. 1757(5-6):474-9.(2) Beck et al. (2007) FASEB J. 21(4):1137-44.(3) Rupprech et al. (2010) Biophys J. 98(8):1503-11.

Influence of ventilation and filtration on indoor particle concentrations in urban office buildings

This study aimed to quantify the efficiency of deep bag and electrostatic filters, and assess the influence of ventilation systems using these filters on indoor fine (<2.5 μm) and ultrafine particle concentrations in commercial office buildings. Measurements and modelling were conducted for different indoor and outdoor particle source scenarios at three office buildings in Brisbane, Australia. Overall, the in-situ efficiency, measured for particles in size ranges 6–3000 nm, of the deep bag filters ranged from 26.3 to 46.9% for the three buildings, while the in-situ efficiency of the electrostatic filter in one building was 60.2%. The highest PN and PM2.5 concentrations in one of the office buildings (up to 131% and 31% higher than the other two buildings, respectively) were due to the proximity of the building's HVAC air intakes to a nearby bus-only roadway, as well as its higher outdoor ventilation rate. The lowest PN and PM2.5 concentrations (up to 57% and 24% lower than the other two buildings, respectively) were measured in a building that utilised both outdoor and mixing air filters in its HVAC system. Indoor PN concentrations were strongly influenced by outdoor levels and were significantly higher during rush-hours (up to 41%) and nucleation events (up to 57%), compared to working-hours, for all three buildings. This is the first time that the influence of new particle formation on indoor particle concentrations has been identified and quantified. A dynamic model for indoor PN concentration, which performed adequately in this study also revealed that using mixing/outdoor air filters can significantly reduce indoor particle concentration in buildings where indoor air was strongly influenced by outdoor particle levels. This work provides a scientific basis for the selection and location of appropriate filters and outdoor air intakes, during the design of new, or upgrade of existing, building HVAC systems. The results also serve to provide a better understanding of indoor particle dynamics and behaviours under different ventilation and particle source scenarios, and highlight effective methods to reduce exposure to particles in commercial office buildings.

Abscisic acid and aldehyde oxidase activity in maize ear leaf and grain relative to post-flowering photosynthetic capacity and grain-filling rate under different water/nitrogen treatments

This study investigated changes in leaf abscisic acid (ABA) concentrations and grain ABA concentrations in two maize cultivars and analyzed the following relationships under different water/nitrogen treatments: leaf ABA concentrations and photosynthetic parameters; leaf ABA concentrations and grain ABA concentrations; leaf/grain ABA concentrations and grain-filling parameters; and aldehyde oxidase (AO,EC 1.2.3.1) activities and ABA concentrations. The ear leaf average AO activities and ABA concentrations were lower in the controlled release urea treatments compared with the conventional urea treatments. The average AO activities in the grains were higher in the controlled release urea treatments, and the ABA concentrations were significantly increased at 11-30 DAF. The Pn and ABA concentrations in ear leaves were negatively correlated. And the Gmean were positively correlated with the grain ABA concentrations at 11-30 DAF and negatively correlated with the leaf ABA concentrations at 20 and 40-50 DAF. The grain ABA concentrations and leaf ABA concentrations were positively correlated. Thus, the Gmean were closely related to the AO activities and to the ear leaf and grain ABA concentrations. As compared to other treatments, the subsoiling and controlled release urea treatment promoted the uptake of water and nitrogen by maize, increased the photosynthetic capacity of the ear leaves, increased the grain-filling rate, and improved the movement of photosynthetic assimilates toward the developing grains. In the cultivar Z958, higher ABA concentrations in grains at 11-30 DAF and lower ABA concentrations in ear leaves during the late grain-filling stage, resulted in higher grain-filling rate and increased accumulation of photosynthetic products (relative to the cultivar D3).

Dissolved and particulate reactive nitrogen in the Elbe River/NW Europe: a 2-yr N-isotope study

Abstract. Rivers collect and transport reactive nitrogen to coastal seas as nitrate, ammonium, dissolved organic nitrogen (DON), or particulate nitrogen. DON is an important component of reactive nitrogen in rivers and is suspected to contribute to coastal eutrophication, but little is known about seasonality of DON loads and turnover within rivers. We measured the concentrations and the isotope ratios 15N/14N of combined DON + NH4+ (δ15DON + NH4+), nitrate (δ15N − NO3−) and particulate nitrogen (δ15PN) in the non-tidal Elbe River (SE North Sea, NW Europe) over a period of 2 yr (June 2005 to December 2007) at monthly resolution. Combined DON + NH4+ concentrations ranged from 22 to 75 μM and comprised nearly 23% of total dissolved nitrogen in the Elbe River in annual mean; PN and nitrate concentrations ranged from 11 to 127 μM, and 33 to 422 μM, respectively. Combined PN and DON + NH4+ concentrations were, to a first approximation, inversely correlated to nitrate concentrations. δ15DON + NH4+, which varied between from 0.8‰ to 11.5‰, changed in parallel to δ15PN (range 6 to 10‰), and both were anti-correlated to δ15N − NO3− (range 6 to 23‰). Seasonal patterns of DON + NH4+ concentrations and δ15DON + NH4+ diverge from those expected from biological DON + NH4+ production in the river alone and suggest that the elution of organic fertilisers significantly affects the DON + NH4+ pool in the Elbe River.

Force-driven unbinding of proteins HU and Fis from DNA quantified using a thermodynamic Maxwell relation

Determining numbers of proteins bound to large DNAs is important for understanding their chromosomal functions. Protein numbers may be affected by physical factors such as mechanical forces generated in DNA, e.g. by transcription or replication. We performed single-DNA stretching experiments with bacterial nucleoid proteins HU and Fis, verifying that the force–extension measurements were in thermodynamic equilibrium. We, therefore, could use a thermodynamic Maxwell relation to deduce the change of protein number on a single DNA due to varied force. For the binding of both HU and Fis under conditions studied, numbers of bound proteins decreased as force was increased. Our experiments showed that most of the bound HU proteins were driven off the DNA at 6.3 pN for HU concentrations lower than 150 nM; our HU data were fit well by a statistical-mechanical model of protein-induced bending of DNA. In contrast, a significant amount of Fis proteins could not be forced off the DNA at forces up to 12 pN and Fis concentrations up to 20 nM. This thermodynamic approach may be applied to measure changes in numbers of a wide variety of molecules bound to DNA or other polymers. Force-dependent DNA binding by proteins suggests mechano-chemical mechanisms for gene regulation.

Zooplankton contribution to the particulate N and P in Lake Kinneret, Israel, under changing water levels

The association of water level changes and the relative (%) contributions of crustacean zooplankton to particulate N (PNz) and particulate P (PPz) in Lake Kinneret, Israel were studied. The PNz and PPz were assessed for a period of 10 years (1999–2008) in relation to water level (WL) changes which occurred during that period. We estimated PNz and PPz, based on crustacean N and P content measured seasonally over 2 years, and a 10-year record of zooplankton densities. Mean cladoceran N and P contents were 8.7 and 1.2% of dry weight, respectively, while for copepods they were 9.5 and 1.5% of dry weight, respectively. Zooplankton density, and hence PNz and PPz, changed dramatically during the 10 years, concurrent with extreme variations in the lake’s WL. The lowest mean values of PNz and PPz occurred during high WL years and the highest PNz and PPz were during low WL years. PNz and PPz were negatively correlated with the total PN and PP concentrations, respectively, in the lake. The reduction in zooplankton contribution to the particulate N and P during high WL is probably due to higher loading of particulate matter in wet years, causing an increase of PN and PP concentration in the lake, as well as lower densities of zooplankton, caused by higher fish predation pressure, both are a by-product of the large water influx during extreme wet winters.

Hydrogen‐bonding, crystallinity, and morphological properties of poly(silicic acid)/waterborne polyurethane nanocomposites

AbstractUnique nanocomposites consisting of poly(silicic acid) nanoparticles (PNs) and waterborne polyurethane (WPU) were prepared. The aliphatic WPU prepared in this study was end‐capped with a silanol group, which could react with PNs via a sol–gel process. PNs were modified with phenyltrimethoxysilane (PTMS) and 3‐(trimethoxysilyl)propyl ester (TMPE) and then blended with WPU. The structure–property relationships were examined. Solid‐state 29Si NMR spectra of WPU showed that structures T1, T2, and T3 of WPU decreased and structures Q3 and Q4 of PN/WPU nanocomposites increased gradually. When the PN concentration increased to 10 wt %, PN/WPU nanocomposites exhibited the maximum fraction of hydrogen‐bonded carbonyl groups. In the PTMS–PN and TMPE–PN systems, the fraction of hydrogen‐bonded carbonyl groups fluctuated stably when the concentrations of PTMS–PN and TMPS–PN exceeded 5 wt %. The X‐ray diffraction results revealed that α‐form, γ‐form, or triclinic crystallization could be found in the WPU matrix. A differential scanning calorimetry spectrum showed that the crystalline structure of the hard segment of WPU was influenced by the nanoparticle concentration. The degrees of crystallinity were 88% for the PN/WPU nanocomposites, 41% for the PTMS–PN/WPU nanocomposites, and 54% for the TMPE–PN/WPU nanocomposites when the PN, PTMS–PN, and TMPE–PN concentrations were 5 wt %. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1076–1089, 2005

Peroxynitrite Reactions with Dimethylsulfide and Dimethylselenide: An Experimental Study

The kinetics of the peroxynitrite (ONOO- and HOONO, PN for both) reaction with (Me)2X (X = S and Se, dimethyl sulfide (DMS) and dimethylselenide (DMSe)) was studied. The reaction is first order with respect to both PN and (Me)2X concentrations. (Me)2XO and NO2- were formed with 100% yield based on PN in all cases except in the DMS reaction with HOONO, where the yield was ∼80%. DMSe is much more reactive than DMS toward both ONOO- and HOONO, while HOONO reacts much faster than ONOO- with both (Me)2X. The activation entropies (in cal deg-1 mol-1) and enthalpies (given in parentheses, in kcal/mol) for the reactions of DMS and DMSe with HOONO were determined to be −23 ± 3 (5.9 ± 0.5) and −20.5 ± 3 (4.6 ± 0.5), respectively. The corresponding values for the reaction with ONOO- were −29 ± 3 (9.7 ± 0.6) and −28 ± 3 (7.2 ± 0.5). A partial replacement of water with an organic cosolvent resulted in a decrease in the rate of reaction of ONOO- with both DMS and DMSe, while it had no effect on the rates of reaction wi...