Increase In Light Transmission Research Articles

Chitosan solutions and films properties obtained using electromagnetic-activated water

Purpose of research: to obtain chitosan films with improved performance properties by using water activated by an electromagnetic field of the radio frequency range as a solvent. Objects of research: water activated by an electromagnetic field of the radio frequency range (90-200 MHz), as well as chitosan solutions and films obtained using it. Methods of research: conductometry, potentiometry, densitometry, viscometry, turbidimetry, gravimetry, IR spectroscopy are used in the work. To determine the deformation and strength characteristics of the films, a universal testing machine with an electromechanical drive УТС-110M was used. Main results of research: The effect of pretreatment of water with an electromagnetic field of various frequencies on the properties of acetic acid (2 %) chitosan solutions in the concentration range of 0.1-2.0% has been studied. A decrease in surface tension by 2.0–5.2 % was found, as well as an increase in light transmission by 10-30 % and viscosity of solutions by 24-37 % at a chitosan concentration of 1.0-2.0 %. These effects are most pronounced for frequencies of 70, 90, 110 and 130 MHz. Films were prepared from 2 % chitosan solutions and their deformation-strength and sorption characteristics with respect to water vapor were determined. The greatest increase in tensile strength was found for chitosan films obtained from solutions prepared on water activated by an electromagnetic field with frequencies of 70 and 110 MHz (38 and 23 %, respectively). A decrease in the hygroscopicity of films and an increase in the intensity of bands in the IR spectra of films obtained using activated water were found.

Human platelet‐mediated transfer of cardioprotection by remote ischemic conditioning is abrogated by aspirin, but not by ticagrelor

BackgroundRepeated ischemia/reperfusion in a tissue/organ remote from the heart (remote ischemic conditioning, RIC) protects against injury from sustained myocardial ischemia/reperfusion (I/R). Platelets are considered as mediators/targets of RIC´s protection. We have recently reported that infusion of washed platelets, taken from healthy volunteers after RIC, reduced infarct size (IS) in isolated rat hearts (FASEB Journal 2021; 35; S1; DOI: 10.1096/fasebj.2021.35.S1.03444). Anti‐platelet drugs are potential confounders of RIC.AimTo study the impact of anti‐platelet drugs, the cyclooxygenase inhibitor aspirin and the P2Y12 inhibitor ticagrelor, on the platelet‐mediated transfer of cardioprotection.MethodsWe included 18 healthy volunteers. As a contemporary control, volunteers were subjected to RIC through 3 x 5 min blood pressure cuff inflation at 200 mmHg on the left upper arm/ 5 min deflation. After at least 2 weeks, these volunteers were again subjected to RIC 3 hours after pretreatment with oral aspirin (500‐1000 mg) and again at least another 2 weeks later 2 hours after pretreatment with oral ticagrelor (180 mg). Venous blood samples were taken before RIC and 60 min after RIC, respectively. Washed platelets were prepared using apyrase, prostaglandin E1 and citrated Tyrode‐buffer. The platelet count was adjusted to 2.5 x 105platelets/µL. The functionality of washed platelets was tested in response to thrombin (1U/ml), aggregation measured with turbodimetric light transmission aggregometry and expressed as the increase in light transmission in percent of control. Platelet preparations with an aggregation <60% were discarded. Male Lewis rats were sacrificed, their hearts isolated and perfused at constant pressure with buffer. Washed platelets before and after RIC, respectively, were infused for 8 min (2.5 x 104 platelets/µL) into rat hearts before global 30 min/ 120 min I/R. IS was demarcated by triphenyl tetrazolium chloride staining and calculated in percent of ventricular mass.ResultsWe confirm, that infusion of platelets after RIC reduces IS in isolated hearts with global I/R (Figure). This platelet‐mediated transfer of cardioprotection was abrogated by aspirin‐pretreatment of the volunteers (Figure). Platelets before RIC from ticagrelor‐pretreated volunteers reduced IS per se; nevertheless, platelets after RIC further reduced IS (Figure).ConclusionHuman platelets serve as carriers for RIC’s cardioprotective signal through an aspirin‐sensitive and thus cyclooxygenase‐dependent mechanism. The P2Y12 inhibitor ticagrelor per se induces a cardioprotective platelet‐dependent signal, which is further enhanced by RIC. The precise signal transfer from the platelets to the myocardium and the nature of the platelet‐derived factors remain to be further identified.

Comparative Spectrophotometer Analysis of Ultraviolet-light Filtering, Blue-light Filtering, and Violet-light Filtering Intraocular Lenses.

PurposeTo compare the light transmittance property of seven currently used intraocular lens (IOL) models by spectrophotometer data.MethodsLight transmission spectra of seven IOL models were assessed with a spectrophotometer. The transmittance properties were analyzed in 1 nm units from 350 nm wavelength to 800 nm.ResultsThree ultraviolet filtering IOL models (ZCB00, XC1-SP, and AT LISA 809M) showed nearly full transmittance of the light from 400 to 500 nm, while steeply attenuating light with shorter wavelengths in various degrees. Three blue-light filtering IOLs (yellow-tinted IOLs; XY1, SN60WF, and TNFT00) showed a slow-sloped increase of light transmission between 400 to 500nm. Among the three, XY1 showed different degree of inclination, showing a steeper slope than SN60WF and TNFT00. The violet-light filtering IOL (ZFR00V) showed a rapid increase of the transmission at around 435 nm wavelength, which is similar to ultraviolet filtering IOLs.ConclusionsThe seven different IOLs measured showed different characteristics of light transmission depending on the properties of each material and color. Blue-light filtering IOLs tend to blocked a wide range of wavelength up to 500 nm, but rather were not effective at the range of 400 to 430 nm. Violet-light filtering IOL showed advantages in filtering the high-energy wavelength, around 430 nm, having a potential risk to retina and allowing the transmission of useful blue and green wavelength which is necessary for a better scotopic contrast sensitivity.

Platelet binding to polymerizing fibrin is avidity driven and requires activated αIIbβ3 but not fibrin cross-linking

AbstractThe molecular basis of platelet-fibrin interactions remains poorly understood despite the predominance of fibrin in thrombi. We have studied the interaction of platelets with polymerizing fibrin by adding thrombin to washed platelets in the presence of the peptide RGDW, which inhibits the initial platelet aggregation mediated by fibrinogen binding to αIIbβ3 but leaves intact a delayed increase in light transmission (delayed wave; DW) as platelets interact with the polymerizing fibrin. The DW was absent in platelets from a patient with Glanzmann thrombasthenia, indicating a requirement for αIIbβ3. The DW required αIIbb3 activation and it was inhibited by the αIIbβ3 antagonists eptifibatide and the monoclonal antibody (mAb) 7E3, but only at much higher concentrations than needed to inhibit platelet aggregation initiated by a thrombin receptor activating peptide (T6). Surface plasmon resonance and scanning electron microscopy studies both supported fibrin having greater avidity for αIIbβ3 than fibrinogen rather than greater affinity, consistent with fibrin's multivalency. mAb 10E5, a potent inhibitor of T6-induced platelet aggregation, did not inhibit the DW, suggesting that fibrin differs from fibrinogen in its mechanism of binding. Inhibition of factor XIII–mediated fibrin cross-linking by >95% reduced the DW by only 32%. Clot retraction showed a pattern of inhibition similar to that of the DW. We conclude that activated αIIbβ3 is the primary mediator of platelet-fibrin interactions leading to clot retraction, and that the interaction is avidity driven, does not require fibrin cross-linking, and is mediated by a mechanism that differs subtly from that of the interaction of αIIbβ3 with fibrinogen.

Surface modification of carbon dots by UV laser radiation

Carbon dots have been modified using UV irradiation (405 nm laser light). UV irradiation of carbon dots has led to various changes in optical properties, which in turn means photomodification of the carbon dots surface. With an increase in light transmission, we have obtained the increasing intensity of photoluminescence and a blue shift by the laser irradiation of the carbon dots. The proposed method can help to adapt and improve the optical properties of carbon dots and can be used in applications, for example, in the optical encryption field.

Fe Thin Film-Coated Optics for Corrosion Monitoring: Optical and Electrochemical Studies

Corrosion proxy materials integrated with an optical sensing platform enable a real-time optical corrosion sensor for natural gas pipelines to prevent methane leaks and catastrophic events. Effects of CO2, pH, and film thickness on corrosion of Fe thin films (25 nm, 50 nm, 100 nm) were studied using optical and electrochemical methods in 3.5 wt.% NaCl solutions at 30°C. An increase in light transmission (T%) corresponded to corrosion of Fe thin films. CO2 accelerated corrosion of Fe thin films because of the lower pH and the promoted corrosion reactions, resulting in a faster increase of T% than without CO2 or at higher pH. While the corrosion rate increased with increasing film thickness, electrochemical corrosion of Fe thin films was in good agreement with that of bulk carbon steel, verifying that Fe thin films can serve as a representative corrosion proxy when integrated with the optical sensing platform.

Theoretical investigation of optical phenomenon from nanometric antireflex layers

SummaryWithin the paper were studied the physical phenomenon which characterize the passing of light through a dielectric environment, a case which can be applied to eyeglass lenses with a nanometric antireflex layer. Were determined the optical characteristics required or such nanometric layers. Was studied practically the increase of light transmission, respectively the reduction of reflection for this new manufacturing technology for eyeglass lenses and the nanometric antireflex layers. The study was completed with photometric measurements and measurements for the resistance of the antireflex coatings compared for several manufacturing technologies.

Increase of light transmission by 10% in the Venlo-type greenhouse: from design to results of a cucumber experiment

During the autumn and winter at higher latitudes natural light is the limiting factor for crop growth in greenhouses. A new greenhouse and cultivation concept has been developed to increase the overall light transmission of the greenhouse with at least 10%. Several innovative elements have been considered: diffuse glass with an anti-reflective coating, high transmission under wet conditions, increased glass panel size, improved screen material, V-shaped screen installation, highly reflective coatings on constructional parts. This has led to an integral design and realization of a 500 m2 greenhouse in 2016 at Wageningen University & Research in the Netherlands. In an earlier study Kempkes et al. (2017) presented the final results of the new Winterlight greenhouse design. According to model calculations a 10.5% gain in PAR sum could be reached during winter. The greenhouse concept has been tested by growing cucumbers. In cooperation with growers a growing strategy has been developed. Besides maximizing the use of natural light, energy consumption was reduced using two movable screens, a balance ventilation system with heat recovery during dehumidification and growing according to the principles of the ‘New Cultivation Strategies’. Light transmission has been measured and was compared with raytracing simulations. Especially during diffuse light conditions, the accuracy was within 1%. On the long-term the difference between calculated and measured PAR sum was below 3%. Greenhouse climate and energy consumption have been compared with those of commercial growers. Energy savings up to 40% and production increases up to 30% were reached growing cucumber ‘High Power’ in the new greenhouse compared to commercial greenhouses. Light transmission was increased with more than 10%. Energy use was 176 kWh m-2 for heat and 2.5 kWh m-2 electricity for the fans of the balance ventilation and heating system. Additionally, 10.2 kg m-2 of CO2 was purchased. Cucumber production was 120 kg m-2 with good quality (284 pcs). An average Dutch grower using the high-wire system uses about 282 kWh m-2 gas equivalents producing around 95 kg m-2.

Nitrogen plasma irradiation of Fe doped ZnO nanowire arrays for improved optical properties

This work reports on the ability to improve the optical properties of hydrothermally grown, vertically-aligned arrays of wurzite ZnO and Fe doped ZnO nanowires by means of nitrogen doping during high-powered plasma irradiation. The morphology, structural and optical properties of ZnO, Fe:ZnO NWs and N2 – Fe:ZnO NWs are studied by scanning electron microscopy, grazing incidence X-ray diffraction and UV–visible spectroscopy, respectively, whereas elemental doping of the nanostructures are investigated by means of X-ray photo-electron spectroscopy. SEM micrographs show no discernible morphological differences between the ZnO, Fe:ZnO NWs and N2-Fe:ZnO NWs, however a clear increase in light transmission over the visible to UV range, accompanied by a decrease in optical band gap of 3.261 eV for ZnO NWs to 3.255 eV for Fe:ZnO NWs and ultimately 3.250 eV for N2-Fe:ZnO nanowires is observed. This band gap reduction is ascribed to the presence of a high density of shallow donor states in the bandgap of the ZnO lattice, subsequently causing an overall reshape of the conduction band minimum, caused by filling of oxygen vacancies and substitutional replacement of lattice oxygen by the highly kinetic α-N species during oxynitride, O-Zn-N bond formation. The results suggest that nitrogen doping during plasma irradiation provides a controlled method of deep lattice nitrogen doping that is favorable for improved photo-electrochemical, photovoltaic and photo-response applications of ZnO nanowires.

Quantitative dynamics of reversible platelet aggregation: mathematical modelling and experiments

Although reversible platelet aggregation observed in response to ADP stimulation in the presence of calcium is a well-known phenomenon, its mechanisms are not entirely clear. To study them, we developed a simple kinetic mass-action-law-based mathematical model to use it in combination with experiments. Light transmission platelet aggregometry (LTA) induced by ADP was performed for platelet-rich plasma or washed platelets using both conventional light transmission and aggregate size monitoring method based on optical density fluctuations. Parameter values of the model were determined by means of parameter estimation techniques implemented in COPASI software. The mathematical model was able to describe reversible platelet aggregation LTA curves without assuming changes in platelet aggregation parameters over time, but with the assumption that platelet can enter the aggregate only once. In the model, the mean size of platelet aggregates correlated with the solution transparency. This corresponded with flow cytometry analysis and with optical density fluctuations data on aggregate size. The predicted values of model parameters correlated with ADP concentration used in experiments. These data suggest that, at the start of the aggregation, when platelet integrins switch “on”, large unstable platelet aggregates are rapidly formed, which leads to an increase in light transmission. However, upon fragmentation of these aggregates, the probability of the post-aggregate platelets’ attachment to each other decreases preventing new aggregation and resulting in the reversible aggregation phenomenon.

Increase of light transmission of a Venlo-type greenhouse during winter by 10%: a design study

During winter and at higher latitudes, natural light is the limiting factor for crop growth in greenhouses. The design of Venlo-type greenhouses in the Netherlands has not changed for many years, although recent developments of diffuse glass with anti-reflective coatings might necessitate alteration of the roof design for maximized light transmissivity during winter. Light transmissivity of a greenhouse, in general, is influenced by roof slope, gutter orientation, roof shape, dimensions, position and reflectivity of construction elements, screen installation, position and transmissivity of screen material, transmissivity and light-scattering pattern of the covering and the effect of condensation on the inner side of the covering material or screen. Using the ray-tracing model RAYPRO (Swinkels et al., 2001), the integral effect of all individual and combined measures on light transmission of the greenhouse at crop level was calculated. The results show that it is possible to increase light transmission by more than 10% with a novel greenhouse roof concept. Results of ray-tracing calculations for individual and combined measures are described in this paper. After identifying the roof concept with the theoretically highest increase in light transmissivity during winter in the Netherlands, economic feasibility and all constructional restrictions were taken into account in close cooperation with industrial partners. This has led to a novel roof design that was built as a demonstration greenhouse on a scale of 500 m2 in summer 2016 at Wageningen University & Research station in Bleiswijk. This “winterlight greenhouse” had resulted in a re-design of the traditional Venlo-type greenhouse roof, covering and screen.

Canopy manipulation as a tool for restoring mature forest conifers under an early‐successional angiosperm canopy

Low‐light environments in early‐successional forests that have established after abandonment of farming often restrict the establishment of later successional species resulting in an arrested succession. This 6‐year study tested the potential of different canopy manipulations to facilitate the establishment of a light‐demanding canopy tree species, tōtara (Podocarpus totara), within a regenerating kānuka (Kunzea robusta) stand. Results highlighted the effectiveness of artificial gaps over other methods (ring‐barking and edge‐planting) in accelerating the growth of planted tōtara. Seedlings under gaps grew consistently taller and faster over time indicative of an improved understorey light environment. Ring‐barking did not have a significant effect on tōtara growth because only a portion of the treated trees died, and after 6 years dead trees remained standing with intact branches resulting in insignificant increases in light transmission. At the forest edge sites, tōtara growth was highly variable. Although some seedlings grew as tall as in the gaps, others did not. Survival was also lower in the edge sites than in other treatments, which was likely due to enhanced herbivory from ungulates which impacted some plants at these sites. Gap creation is likely to be an important tool for restoring late‐successional canopy species in regenerating stands both through providing ideal sites for the growth of light‐demanding species such as tōtara and through natural establishment of other future canopy trees into the gaps.

Bringing transparent microelectrodes to market: Evaluation for production and real-world applications

Event Abstract Back to Event Bringing transparent microelectrodes to market: Evaluation for production and real-world applications Michael Mierzejewski1, Pranoti Kshirsagar1, Udo Kraushaar1, Gerhard Heusel1, Ramona Samba2 and Peter D. Jones1* 1 Natural and Medical Sciences Institute, Germany 2 NMI Technologie Transfer GmbH, Germany Introduction Microelectrode arrays (MEAs) are used for a number of applications in electrophysiology, with the ability to record field action potentials (fAP) from cardiomyocytes and neurons, as well as selectively induce a potential on an electrode in the array. This technology makes high throughput monitoring of field potentials possible, but the materials used in commercially-available MEAs can inhibit visual recording or stimulation. While transparent conductors such as indium tin oxide (ITO) are used for conducting traces, the need for microelectrodes to have stable, low electrochemical impedance has necessitated the use of opaque materials such as titanium nitride (TiN), gold (Au), platinum (Pt), and platinum iridium (Pt/Ir). Any bright-field microscopy will lead to a shadow being cast onto the cells above the electrode, resulting in a loss of potentially useful information. To remedy this issue, several groups have been working on transparent microelectrode materials such as Au-mesh coated with conducting polymer [1] and carbon nanomaterials [2-5]. To the best of our knowledge, no MEA with transparent microelectrodes is currently commercially available. The purpose of this project is to evaluate multiple transparent materials to complement those opaque materials currently on the market. Specifically, we are investigating the material properties, suitability for scalable production, stability against sterilization and during cell culture, and evaluating their application in opto- and electrophysiology in cardiac and neural applications. This technology has the potential to advance the current trend of combining electrophysiology with optophysiology. Materials and Methods We are evaluating various transparent materials against state-of-the-art titanium nitride (TiN) microelectrodes. Standard (opaque) and transparent titanium nitride microelectrodes have been fabricated in an 8x8 MEA configuration with ITO traces, SiNx as the insulator, electrode size of 30 µm, and pitch of 200 µm. Carbon nanomaterials and conducting polymers are also being considered as potential materials for transparent electrodes. Impedance spectroscopy was performed with a Bio-logic VMP3 potentiostat at an amplitude of 10 mV from 1 Hz to 100 kHz. Noise measurements were performed using 150 mM phosphate buffered saline (PBS) as the medium, utilizing a MEA2100-system from Multi Channel Systems (MCS). Cardiomyocytes were isolated from embryonic chicken ventricles after 13 days in incubation, and 80 k cells were subsequently plated on each MEA after coating with nitrocellulose. Recordings were taken of these samples in a 3 % Fetal Calf Serum (FCS) medium after 6 days in vitro. Optical transmission measurements were taken with a bright-field Zeiss microscope, performing a line scan across the electrodes. Results and Discussion Characterization of the transparent electrodes showed an increase in transparency, noise, and impedance in comparison to the standard electrodes. An increase in impedance of ~150 kΩ (Figure 1b) led to an increase in peak-to-peak noise of 10 µV when compared against standard opaque electrodes. This increase of impedance and noise is accompanied by a 40 % absolute increase in transmission of light in the visible spectrum (400–700 nm) as shown in Figure 1d. The electrodes were then compared against each other in a real world application. Measurement of fAP from the cardiomyocytes showed the effect of the increased noise and transmission observed during the characterization. This increase in noise affected the clarity of the cardiomyocyte recordings, but cellular activity such as the repolarization event in Figure 1c was still visible. While the recordings were impacted by the characteristics of the transparent material, the increased transmission allowed for cells on top of the electrode to be visible under bright-field spectroscopy. Conclusion and Outlook Preliminary results show that increased transparency can be attained in exchange for increased impedance, and subsequent increased noise. The increase in transparency does allow for the ability to view cells which would normally be obstructed by the electrode. This will provide new capabilities for specific applications where observation or optical stimulation of the cells is important to the application. With continued work on this project we aim to further evaluate transparent TiN as well as materials including carbon nanomaterials and conducting polymers. Along with testing the impedance and noise of all the electrodes, we plan to put the MEAs through real world scenarios to see how well they can be used in research applications. This will include investigating the limits that the MEAs can withstand regarding standard cleaning and sterilization procedures, as well as how well the MEAs withstand extended or repeated cell cultures. Figure 1 Figure 2 Acknowledgements We thank the NMI TT GmbH for supporting MEA fabrication, Sandra Buckenmaier for cardiomyocyte cell culturing and Simon Dickreuter for optical transmittance measurements.

Developmental Changes in Sensory-Evoked Optical Intrinsic Signals in the Rat Barrel Cortex.

Optical Intrinsic Signal imaging (OISi) is a powerful technique for optical brain studies. OIS mainly reflects the hemodynamic response (HR) and metabolism, but it may also involve changes in tissue light scattering (LS) caused by transient cellular swelling in the active tissue. Here, we explored the developmental features of sensory-evoked OIS in the rat barrel cortex during the first 3 months after birth. Multispectral OISi revealed that two temporally distinct components contribute to the neonatal OIS: an early phase of LS followed by a late phase of HR. The contribution of LS to the early response was also evidenced by an increase in light transmission through the active barrel. The early OIS phase correlated in time and amplitude with the sensory-evoked electrophysiological response. Application of the Modified Beer-Lambert Law (MBLL) to the OIS data revealed that HR during the early phase involved only a slight decrease in blood oxygenation without any change in blood volume. In contrast, HR during the late phase manifested an adult-like increase in blood volume and oxygenation. During development, the peak time of the delayed HR progressively shortened with age, nearly reaching the stimulus onset and overlapping with the early LS phase by the fourth postnatal week. Thus, LS contributes to the sensory-evoked OIS in the barrel cortex of rats at all ages, and it dominates the early OIS phase in neonatal rats due to delayed HR. Our results are also consistent with the delayed blood oxygen level dependent (BOLD) signal in human preterm infants.

Effect of shade, opacity and layer thickness on light transmission through a nano-hybrid dental composite during curing.

The aim of this study was to investigate the effect of shade and opacity on the change in light transmission through different thicknesses of a nano-hybrid composite during curing. Twelve different shades of Venus Diamond (Heraeus Kulzer) were placed in disk shaped molds with thickness of 1, 2, and 3 mm (n = 3 per group) and cured with an LED light-curing unit. Initial, final and average irradiance, and the total amount of energy passing through the specimen were measured using the MARC Resin Calibrator at every 10s for a total of 40s. The translucency parameter and the contrast ratio were obtained using a chromameter. Results were analyzed with ANOVA/Tukey's test (α = 0.05). All shades and all thicknesses (up to 3 mm) experienced an increase in light transmittance during curing. The majority of the increase occurred during the initial 10s exposure, with significant increase occurring from subsequent exposures only in thicker specimens (i.e., 3 mm). The increase in irradiance at the bottom during curing was dependent on shade, with darker shades and greater depths of material showing less increase. For one specific resin composite formulation, an increase in translucency occurs as cure progresses, and the increase is enhanced for composites with greater lightness and lower contrast ratio. Composites demonstrate increased light transmittance as curing progress, which may improve depth of cure. The thicker composite showed the least increase in light transmission within the same shade. The increase in translucency is enhanced for composites with great lightness and lower contrast ratio.

Sprouting capacity of Persea borbonia and maritime forest community response to simulated laurel wilt disease

There are numerous examples of how exotic insect pests and pathogens have altered the dominance of native tree species. Changes to the structure of associated communities will depend on whether the affected species survives and if so, the degree to which it is diminished. In the southeastern USA, Persea borbonia, a common tree found in many coastal plain habitats, is the primary host of laurel wilt disease (LWD); infection rates and main-stem mortality are catastrophically high (>90%) in invaded populations. We simulated the effects of LWD prior to its arrival in coastal Mississippi by girdling and then removing the main stems of P. borbonia trees. Over a 2-year period, we monitored P. borbonia persistence via basal resprouts, understory light availability, and community structure. Removal of P. borbonia main stems resulted in a 50% increase in light transmission (measured at 1 m above ground level). All treated individuals produced basal resprouts, the size and number of which were positively related to initial tree girth. Post-treatment increases in basal area were greatest for the sub-canopy species, Ilex vomitoria, and were significantly higher in treatment versus control plots. Woody seedlings and herbaceous plants showed no significant trends in composition and abundance over time or between control and treatment plots. Our results suggest that removal of P. borbonia and subsequent resprouting causes shifts in P. borbonia size class frequencies and sub-canopy species dominance but has negligible impacts on understory plant community dynamics.

Investigation of the Effect of Yttrium Oxide Nanoparticles Doped with Cerium and Neodymium on Electro-Optics of Liquid Crystal Polymer Composites

Morphology and properties of liquid crystal polymer composites doped with inorganic nanoparticles are described. These composites comprised nematic liquid crystal 5CB, polyvinyl acetate, and nanoparticles of oxides (Y2O3, CeO2:Y2O3, and Nd2O3:Y2O3). Nanopowders were synthesized by the laser method of vaporization of a solid target under CO2-laser or fiber ytterbium laser irradiation. The effect of oxides on the electro-optical properties of the composites and times of response to an electrical pulse is investigated. It is shown that incorporation of CeO2:Y2O3 nanopowder in liquid crystal polymer composites affects the decrease of the control field and the increase of light transmission in an electric field stronger than incorporation of Nd2O3:Y2O3 nanoparticles.

Uniform silver nanoparticles coating using dual regime spray deposition system for superhydrophilic and antifogging applications

Antifogging and/or superhydrophilic properties of coatings are widely exploited both in a laboratory environment and in industrial applications. Material choice for the production of the coatings is of vital importance for the final coating properties. Silver nanoparticles have been known to have antibacterial and fungicidal properties, which make them extremely useful in biomedical applications. Production of coatings that combine superhydrophilic and the unique properties of silver nanoparticles can be beneficial in numerous applications. Dual regime spray coating system allows for the production of a thin, uniformly distributed nanoparticle coating through droplet impact velocity and gas flow control. Silver nanoparticles of ~15 nm average diameter were synthesized and coated onto the glass substrate, which produced the top layer with strong superhydrophilic/antifogging properties with water contact angles of close to 6°. In addition, coated surfaces exhibited an increase in light transmission of ~0.7% in the 500–700 nm range.

The potential role of sea ice melt in the distribution of chromophoric dissolved organic matter in the Chukchi and Beaufort Seas

We investigated chromophoric dissolved organic matter (CDOM) in sea ice and the underlying water column in the Chukchi and Beaufort seas of the Pacific Arctic region and its relationship with both physical and biogeochemical parameters. Sea ice, water and melt pond samples were collected as sea ice melted in June–July 2010 and 2011. CDOM absorption was found to be significantly lower in sea ice compared to under-ice waters. In particular, the average CDOM absorption coefficient at 254nm was approximately four times greater in the underlying water column than in the overlying ice. This indicates that melting sea ice did not contribute to net CDOM at this point in the melt season, but rather diluted CDOM in the under-ice water column. In the 2011 under-ice water column samples, the average CDOM absorption coefficients at 440nm were twice as high along a transect associated with high phytoplankton biomass, which may have been contributed through subsequent microbial generation of CDOM. Less extensive sea ice cover with melt ponds may also have increased the presence of CDOM owing to increases in light transmission, leading to under-ice phytoplankton blooms and associated microbial production. However, oxygen isotope analysis of these waters with high under-ice phytoplankton biomass also indicates the presence of prior sea ice melt, including potentially sea ice algae and microbes, which could have also contributed to this anomalously high CDOM. These observations suggest that while melting sea ice may not necessarily contribute to increased CDOM concentrations, there are circumstances where CDOM in underlying waters may be higher than expected, either due to enhanced light transmission and higher under-ice production, and/or prior ice melt that provided significant contributions to under-ice CDOM.

Dynamics of the photosystem II photochemical activity in the developing <em>Brassica nigra</em> L. seeds

Dynamics of the PS II activity in the pod walls, seed coat and embryo cotyledons at early and middle maturation stages of Brassica nigra L. has been studied using the Junior-PAM fluorometer (Heinz Walz Gmbh, Germany). The maximum quantum yield Fv/Fm, effective quantum yield Y(II) and coefficient of photochemical fluorescence quenching qP have been evaluated. We demonstrated maturation-dependent fluctuation of the PS II activity in the different part of seeds: Fv/Fm, Y(II) and qP decreased in the pod walls and seed coat, but increased in the cotyledons of embryo. During transition from early to middle stage of maturation, the maximal electron transport rate of PS II in the cotyledons increased and reached the maximum at higher level of photosynthetic active radiation. Improving the efficiency of PS II in the developing cotyledons of the embryo can be attributed to adaptation of the chloroplasts to a higher light probably due to the increase of light transmission through the seed coat and pericarp at later stages of seed maturation. Refs 29. Figs. 3.