Showing papers on "Light intensity published in 2011"

Influence of abiotic stress signals on secondary metabolites in plants

Abstract: Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and industrially important biochemicals. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Secondary metabolites play a major role in the adaptation of plants to the environment and in overcoming stress conditions. Environmental factors viz. temperature, humidity, light intensity, the supply of water, minerals, and CO2 influence the growth of a plant and secondary metabolite production. Drought, high salinity, and freezing temperatures are environmental conditions that cause adverse effects on the growth of plants and the productivity of crops. Plant cell culture technologies have been effective tools for both studying and producing plant secondary metabolites under in vitro conditions and for plant improvement. This brief review summarizes the influence of different abiotic factors include salt, drought, light, heavy metals, frost etc. o...

Aerosol measurement : principles, techniques, and applications

Abstract: Preface. List of Principal Symbols. Contributors. PART I: PRINCIPLES. Historical Aspects of Aerosol Measurements (K. Spurny). Bridging Science and Application in Aerosol Measurement: Accessing Available Tools (P. Baron and K. Willeke). Aerosol Fundamentals (P. Baron and K. Willeke). Gas and Particle Motion (P. Baron, K. Willeke). Physical and Chemical Changes in the Particulate Phase (W. Hinds). Size Distribution Characteristics of Aerosols (W. John). An Approach to Performing Aerosol Measurements (P. Baron and W. Heitbrink). PART II: TECHNIQUES. Sampling and Transport of Aerosols (J. Brockmann). Filter Collection (K. Lee and R. Mukund). Inertial Gravitational, Centrifugal and Thermal Collection Techniques (V. Marple, et al.). Chemical Analysis Methods for Atmospheric Aerosol Components (P. Solomon, et al.). Analysis of Individual Collected Particles (R. Fletcher, et al.). Real--Time Single--Particle Analysis (A. Wexler and M. Johnston). Dynamic Mass and Surface Area Measurements (U. Baltensperger, et al.). Optical Direct--Reading Techniques: Light Intensity Systems (J. Gebhart). Optical Direct--Reading Techniques: In Situ Sensing (D. Rader and T. O'Hern). Direct--Reading Techniques Optical Particle Motion and Optical Detection (P. Baron, et al.). Electrical Techniques (R. Flagan). Condensation Detection and Diffusion Size Separation Techniques (Y.--S. Cheng). Electrodynamic Levitation of Particles (E. Davis). Instrument Calibration (B. Chen and W. John). Methods of Size Distribution Data Analysis and Presentation (D. Cooper). PART III: APPLICATIONS. Nonspherical Particles Measurement: Shape Factors, Fractals, and Fibers (P. Baron, et al.). Biological Particle Sampling (T. Reponen, et al.). Aerosol Measurement in the Workplace (A. Maynard and P. Jensen). Mine Aerosol Measurement (B. Cantrell and J. Volkwein). Ambient Air Sampling (J. Watson and J. Chow).Fugitive Dust Emissions (C. Cowherd). Indoor Aerosols and Aerosol Assessment (C. Rodes and R. Wiener). Measurement of Aerosol from Aircraft (J. Wilson and W. Seebaugh). Measurement of High--Concentration and High--Temperature Aerosols (P. Biswas). Manufacturing of Materials by Aerosols Processes (S. Pratsinis, et al.). Aerosol Measurements in Cleanrooms (R. Donovan). Radioactive Aerosols (M. Hoover and G. Newton). Radon and Its Short--Lived Decay Product Aerosols (B. Cohen). Aerosol Measurement of Pharmaceutical and Diagnostic Aerosols (A. Hickey and D. Swift). Inhalation Toxicology: Sampling Strategies Related to Control of Exposure Atmospheres (O. Moss). Appendix A: Glossary of Terms. Appendix B: Conversion Factors. Appendix C: Commonly Used Constants. Appendix D: Some Properties of Air and Water. Appendix E: Major Dimensionless Numbers. Appendix F: Properties of Particles. Appendix G: Geometric Formulas Appendix H: Bulk Density of Some Common Aerosol Materials. Appendix I: Manufacturers and Suppliers. Index.

The effect of light, salinity, and nitrogen availability on lipid production by Nannochloropsis sp.

Abstract: We examined responses of batch cultures of the marine microalga Nannochloropsis sp. to combined alterations in salinity (13, 27, and 40 g/l NaCl) and light intensity (170 and 700 μmol photons/m2·s). Major growth parameters and lipid productivity (based on total fatty acid determination) were determined in nitrogen-replete and nitrogen-depleted cultures of an initial biomass of 0.8 and 1.4 g/l, respectively. On the nitrogen-replete medium, increases in light intensity and salinity increased the cellular content of dry weight and lipids due to enhanced formation of triacylglycerols (TAG). Maximum average productivity of ca. 410 mg TFA/l/d were obtained at 700 μmol photons/m2·s and 40 g/l NaCl within 7 days. Under stressful conditions, content of the major LC-PUFA, eicosapentaenoic acid (EPA), was significantly reduced while TAG reached 25% of biomass. In contrast, lower salinity tended to improve major growth parameters, consistent with less variation in EPA contents. Combined higher salinity and light intensity was detrimental to lipid productivity under nitrogen starvation; biomass TFA content, and lipid productivity amounted for only 33% of DW and ca. 200 mg TFA/l/day, respectively. The highest biomass TFA content (ca. 47% DW) and average lipid productivity of ca. 360 mg TFA/l/day were achieved at 13 g/l NaCl and 700 μmol photons/m2·s. Our data further support selecting Nannochloropsis as promising microalgae for biodiesel production. Moreover, appropriate cultivation regimes may render Nannochloropsis microalgae to produce simultaneously major valuable components, EPA, and TAG, while sustaining relatively high biomass growth rates.

Seeing protein monolayers with naked eye through plasmonic Fano resonances

Abstract: We introduce an ultrasensitive label-free detection technique based on asymmetric Fano resonances in plasmonic nanoholes with far reaching implications for point-of-care diagnostics. By exploiting extraordinary light transmission phenomena through high-quality factor (Qsolution ∼ 200) subradiant dark modes, we experimentally demonstrate record high figures of merits (FOMs as high as 162) for intrinsic detection limits surpassing that of the gold standard prism coupled surface-plasmon sensors (Kretschmann configuration). Our experimental record high sensitivities are attributed to the nearly complete suppression of the radiative losses that are made possible by the high structural quality of the fabricated devices as well as the subradiant nature of the resonances. Steep dispersion of the plasmonic Fano resonance profiles in high-quality plasmonic sensors exhibit dramatic light intensity changes to the slightest perturbations within their local environment. As a spectacular demonstration of the extraordinary sensitivity and the quality of the fabricated biosensors, we show direct detection of a single monolayer of biomolecules with naked eye using these Fano resonances and the associated Wood’s anomalies. To fabricate high optical-quality sensors, we introduce a high-throughput lift-off free evaporation fabrication technique with extremely uniform and precisely controlled nanofeatures over large areas, leading to resonance line-widths comparable to that of the ideally uniform structures as confirmed by our time-domain simulations. The demonstrated label-free sensing platform offers unique opportunities for point-of-care diagnostics in resource poor settings by eliminating the need for fluorescent labeling and optical detection instrumentation (camera, spectrometer, etc.) as well as mechanical and light isolation.

Manipulation of photoprotection to improve plant photosynthesis

Abstract: Light is of course essential for photosynthesis and supports most life on earth. However, light intensity and spectral quality are highly variable in space and time according to time of day, season, geography, climate, and the position of leaf within canopy and cell within leaf. This has resulted in

Microalgae--novel highly efficient starch producers.

Abstract: The freshwater alga Chlorella, a highly productive source of starch, might substitute for starch-rich terrestrial plants in bioethanol production. The cultivation conditions necessary for maximizing starch content in Chlorella biomass, generated in outdoor scale-up solar photobioreactors, are described. The most important factor that can affect the rate of starch synthesis, and its accumulation, is mean illumination resulting from a combination of biomass concentration and incident light intensity. While 8.5% DW of starch was attained at a mean light intensity of 215 µmol/(m2 s1), 40% of DW was synthesized at a mean light intensity 330 µmol/(m2 s1). Another important factor is the phase of the cell cycle. The content of starch was highest (45% of DW) prior to cell division, but during the course of division, its cellular level rapidly decreased to about 13% of DW in cells grown in light, or to about 4% in those kept in the dark during the division phase. To produce biomass with high starch content, it is necessary to suppress cell division events, but not to disturb synthesis of starch in the chloroplast. The addition of cycloheximide (1 mg/L), a specific inhibitor of cytoplasmic protein synthesis, and the effect of element limitation (nitrogen, sulfur, phosphorus) were tested. The majority of the experiments were carried out in laboratory-scale photobioreactors, where culture treatments increased starch content to up to about 60% of DW in the case of cycloheximide inhibition or sulfur limitation. When the cells were limited by phosphorus or nitrogen supply, the cellular starch content increased to 55% or 38% of DW, respectively, however, after about 20 h, growth of the cultures stopped producing starch, and the content of starch again decreased. Sulfur limited and cycloheximide-treated cells maintained a high content of starch (60% of DW) for up to 2 days. Sulfur limitation, the most appropriate treatment for scaled-up culture of starch-enriched biomass, was carried out in an outdoor pilot-scale experiment. After 120 h of growth in complete mineral medium, during which time the starch content reached around 18% of DW, sulfur limitation increased the starch content to 50% of DW. Biotechnol. Bioeng. 2011; 108:766–776. © 2010 Wiley Periodicals, Inc.

Advances in Heterogeneous Photocatalytic Degradation of Phenols and Dyes in Wastewater: A Review

Abstract: The heterogeneous photocatalytic water purification process has gained wide attention due to its effectiveness in degrading and mineralizing the recalcitrant organic compounds as well as the possibility of utilizing the solar UV and visible light spectrum. This paper aims to review and summarize the recently published works in the field of photocatalytic oxidation of toxic organic compounds such as phenols and dyes, predominant in wastewater effluent. In this review, the effects of various operating parameters on the photocatalytic degradation of phenols and dyes are presented. Recent findings suggested that different parameters, such as type of photocatalyst and composition, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidizing agents/electron acceptors, mode of catalyst application, and calcinations temperature can play an important role on the photocatalytic degradation of organic compounds in water environment. Extensive research has focused on the enhancement of photocatalysis by modification of TiO2 employing metal, non-metal, and ion doping. Recent advances in TiO2 photocatalysis for the degradation of various phenols and dyes are also highlighted in this review.

Optical indicia reading terminal with combined illumination

Abstract: An optical indicia reading terminal ( 100 ) can comprise an image sensor ( 62,1032 ), an imaging lens ( 1110 ) configured to focus an image of decodable indicia ( 15 ) on the image sensor ( 62,1032 ), an analog-to-digital converter ( 1037 ) configured to convert an analog signal read out of the image sensor ( 62,1032 ) into a digital signal representative of light incident on the image sensor ( 62,1032 ), a hand held housing ( 52 ) encapsulating the image sensor ( 62,1032 ), a microprocessor ( 1060 ) configured to output a decoded message data corresponding to the decodable indicia ( 15 ) by processing the digital signal, and an illumination assembly ( 1207 ). The illumination assembly ( 1207 ) can include at least one visible spectrum illumination source ( 322 a - 322 z ) and at least one invisible spectrum illumination source ( 324 a - 324 z ). The visible spectrum illumination source ( 322 a - 322 z ) can be configured to emit a light having a wavelength belonging to a visible spectrum region. The invisible spectrum illumination source ( 324 a - 324 z ) can be configured to emit a light having a wavelength belonging to an invisible spectrum region. The intensities of light emitted by the visible spectrum light sources ( 322 a - 322 z ) and invisible spectrum light sources ( 324 a - 324 z ) can be chosen to minimize a perceived combined light intensity while providing an illumination sufficient for obtaining an image suitable for decoding the decodable indicia ( 15 ).

Advances in heterogeneous photocatalytic degradation of phenols and dyes in wastewater : a review

Abstract: The heterogeneous photocatalytic water purification process has gained wide attention due to its effectiveness in degrading and mineralizing the recalcitrant organic compounds as well as the possibility of utilizing the solar UV and visible light spectrum. This paper aims to review and summarize the recently published works in the field of photocatalytic oxidation of toxic organic compounds such as phenols and dyes, predominant in waste water effluent. In this review, the effects of various operating parameters on the photocatalytic degradation of phenols and dyes are presented. Recent findings suggested that different parameters, such as type of photocatalyst and composition, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidizing agents/electron acceptors, mode of catalyst application, and calcinations temperature can play an important role on the photocatlytic degradation of organic compounds in water environment. Extensive research has focused on the enhancement of photocatalysis by modification of TiO2 employing metal, non-metal and ion doping. Recent advances in TiO2 photocatalysis for the degradation of various phenols and dyes are also highlighted in this review.

High‐density kinetic analysis of the metabolomic and transcriptomic response of Arabidopsis to eight environmental conditions

Abstract: The time-resolved response of Arabidopsis thaliana towards changing light and/or temperature at the transcriptome and metabolome level is presented. Plants grown at 21°C with a light intensity of 150 μE m⁻² sec⁻¹ were either kept at this condition or transferred into seven different environments (4°C, darkness; 21°C, darkness; 32°C, darkness; 4°C, 85 μE m⁻² sec⁻¹; 21 °C, 75 μE m⁻² sec⁻¹; 21°C, 300 μE m⁻² sec⁻¹ ; 32°C, 150 μE m⁻² sec⁻¹). Samples were taken before (0 min) and at 22 time points after transfer resulting in (8×) 22 time points covering both a linear and a logarithmic time series totaling 177 states. Hierarchical cluster analysis shows that individual conditions (defined by temperature and light) diverge into distinct trajectories at condition-dependent times and that the metabolome follows different kinetics from the transcriptome. The metabolic responses are initially relatively faster when compared with the transcriptional responses. Gene Ontology over-representation analysis identifies a common response for all changed conditions at the transcriptome level during the early response phase (5-60 min). Metabolic networks reconstructed via metabolite-metabolite correlations reveal extensive environment-specific rewiring. Detailed analysis identifies conditional connections between amino acids and intermediates of the tricarboxylic acid cycle. Parallel analysis of transcriptional changes strongly support a model where in the absence of photosynthesis at normal/high temperatures protein degradation occurs rapidly and subsequent amino acid catabolism serves as the main cellular energy supply. These results thus demonstrate the engagement of the electron transfer flavoprotein system under short-term environmental perturbations.

The ecological significance of phenology in four different tree species: effects of light and temperature on bud burst

Abstract: The process of adaptation is the result of stabilising selection caused by two opposite forces: protection against an unfavourable season (survival adaptation), and effective use of growing resources (capacity adaptation). As plant species have evolved different life strategies based on different trade offs between survival and capacity adaptations, different phenological responses are also expected among species. The aim of this study was to compare budburst responses of two opportunistic species (Betula pubescens, and Salix x smithiana) with that of two long-lived, late successional species (Fagus sylvatica and Tilia cordata) and consider their ecological significance. Thus, we performed a series of experiments whereby temperature and photoperiod were manipulated during dormancy. T. cordata and F. sylvatica showed low rates of budburst, high chilling requirements and responsiveness to light intensity, while B. pubescens and S. x smithiana had high rates of budburst, low chilling requirements and were not affected by light intensity. In addition, budburst in B. pubescens and S. x smithiana was more responsive to high forcing temperatures than in T. cordata and F. sylvatica. These results suggest that the timing of growth onset in B. pubescens and S. x smithiana (opportunistic) is regulated through a less conservative mechanism than in T. cordata and F. sylvatica (long-lived, late successional), and that these species trade a higher risk of frost damage for the opportunity of vigorous growth at the beginning of spring, before canopy closure. This information should be considered when assessing the impacts of climate change on vegetation or developing phenological models.

Electrical and Photosensitive Characteristics of a-IGZO TFTs Related to Oxygen Vacancy

Abstract: The electrical and photosensitive characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) related to the oxygen vacancies VO are discussed. With the filling of VO of ratio from 14 to 8, the electron density of the a-IGZO channel decreases from 7.5 to 3.8 ( ×1016 cm-3); the saturation mobility of the TFT decreases from 3.1 to 1.4 cm-2/(V · s); the threshold voltage increases from 7 to 11 V for the TFT with a lower on-current; and the subthreshold slope increases from 2.4 to 4.4 V/dec for the TFT with a higher interface defect density of 4.9 × 1011 cm-2, the worst electrical stability of Vth ~ 10 V, and a hysteresis-voltage decrease from 3.5 to 2 V. The photoreaction properties of a-IGZO TFTs are also sensitive to the oxygen-content-related absorption of the a-IGZO channel. With the lowest content of oxygen in the channel, the TFT has the largest photocurrent gain of 50 μA (Vg = 30 V; Vd = 10 V) and decrease in Vth ( Vth V) at a high light intensity. The light-induced change of TFT characteristics is totally reversible with the time constant for recovery of about 2.5 h.

Influence of the interfacial charge-transfer resistance at the counter electrode in dye-sensitized solar cells employing cobalt redox shuttles

Abstract: We highlight the effect of the interfacial charge-transfer resistance at the counter electrode in dye-sensitized solar cells based on two cobalt redox shuttles, namely cobalt(III/II) tris(2,2′-bipyridine) and cobalt(III/II) tris(1,10-phenanthroline). Highly porous counter electrodes based on poly(3,4-ethylenedioxythiophene) (PEDOT) prepared by electro-oxidative polymerization are compared to the typically employed platinized FTO glass, with the former showing much lower charge transfer resistances for both cobalt complexes, leading to improved fill factors and to linear response of the short circuit photo-current density to light intensity up to one sun. Based on these findings, an excellent power conversion efficiency of 10.3% was achieved with a recently reported organic sensitizer and PEDOT as counter electrode.

Base-calling for next-generation sequencing platforms

Abstract: Next-generation sequencing platforms are dramatically reducing the cost of DNA sequencing. With these technologies, bases are inferred from light intensity signals, a process commonly referred to as base-calling. Thus, understanding and improving the quality of sequence data generated using these approaches are of high interest. Recently, a number of papers have characterized the biases associated with base-calling and proposed methodological improvements. In this review, we summarize recent development of base-calling approaches for the Illumina and Roche 454 sequencing platforms.

Electron Transport and Recombination in ZnO-Based Dye-Sensitized Solar Cells

Abstract: The photovoltaic performance of ZnO-based dye-sensitized solar cells (DSCs) has been studied for three different configurations involving two dyes and two types of electrolytes with the iodide/iodine as redox mediator: ZnO/N719/organic solvent electrolyte (C1), ZnO/D149/organic solvent electrolyte (C2), and ZnO/N719/ionic liquid electrolyte (C3). The DSCs were characterized by measuring current–voltage curves and photovoltage as a function of light intensity and by electrochemical impedance spectroscopy (EIS), intensity-modulated photocurrent spectroscopy (IMPS), intensity-modulated photovoltage spectroscopy (IMVS), and open circuit photovoltage decay (OCVD). The results demonstrate the good light harvesting properties of the D149 dye and highlight the photovoltage limitation of the solvent-free (ionic liquid) electrolyte. The intensity dependence of the photovoltage and the OCVD, EIS, and IMVS results provide evidence of the nonlinear character of the recombination kinetics. It has been found that by com...

Role of charge recombination processes in photodamage and photoprotection of the photosystem II complex

Abstract: Light-induced damage of the photosynthetic apparatus is an important and complex phenomenon, which affects primarily the photosystem II (PSII) complex. Here, the author summarizes the current state of understanding, which concerns the role of charge recombination reactions in photodamage and photoprotection. The main mechanism of photodamage induced by visible light appears to be mediated by acceptor side modifications, which develop under light intensity conditions when the capacity of light-independent photosynthetic processes limits the utilization of electrons produced in the initial photoreactions. This situation facilitates triplet chlorophyll formation and singlet oxygen production in the reaction center of PSII, which initiates the damage of electron transport components and protein structure. This mechanism is an important, but not exclusive, pathway of photodamage, and light-induced inactivation of the Mn cluster of water oxidation may occur in parallel with the singlet oxygen-dependent pathway.

Phototherapy to prevent severe neonatal hyperbilirubinemia in the newborn infant 35 or more weeks of gestation.

Abstract: OBJECTIVE: To standardize the use of phototherapy consistent with the American Academy of Pediatrics clinical practice guideline for the management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation. METHODS: Relevant literature was reviewed. Phototherapy devices currently marketed in the United States that incorporate fluorescent, halogen, fiber-optic, or blue light-emitting diode light sources were assessed in the laboratory. RESULTS: The efficacy of phototherapy units varies widely because of differences in light source and configuration. The following characteristics of a device contribute to its effectiveness: (1) emission of light in the blue-to-green range that overlaps the in vivo plasma bilirubin absorption spectrum (∼460–490 nm); (2) irradiance of at least 30 μW·cm −2 ·nm −1 (confirmed with an appropriate irradiance meter calibrated over the appropriate wavelength range); (3) illumination of maximal body surface; and (4) demonstration of a decrease in total bilirubin concentrations during the first 4 to 6 hours of exposure. RECOMMENDATIONS (SEE APPENDIX FOR GRADING DEFINITION): The intensity and spectral output of phototherapy devices is useful in predicting potential effectiveness in treating hyperbilirubinemia (group B recommendation). Clinical effectiveness should be evaluated before and monitored during use (group B recommendation). Blocking the light source or reducing exposed body surface should be avoided (group B recommendation). Standardization of irradiance meters, improvements in device design, and lower-upper limits of light intensity for phototherapy units merit further study. Comparing the in vivo performance of devices is not practical, in general, and alternative procedures need to be explored.

A mitochondrial GABA permease connects the GABA shunt and the TCA cycle, and is essential for normal carbon metabolism

Abstract: Summary In plants, γ-aminobutyric acid (GABA) accumulates in the cytosol in response to a variety of stresses. GABA is transported into mitochondria, where it is catabolized into TCA cycle or other intermediates. Although there is circumstantial evidence for mitochondrial GABA transporters in eukaryotes, none have yet been identified. Described here is an Arabidopsis protein similar in sequence and topology to unicellular GABA transporters. The expression of this protein complements a GABA-transport-deficient yeast mutant. Thus the protein was termed AtGABP to indicate GABA-permease activity. In vivo localization of GABP fused to GFP and immunobloting of subcellular fractions demonstrate its mitochondrial localization. Direct [3H]GABA uptake measurements into isolated mitochondria revealed impaired uptake into mitochondria of a gabp mutant compared with wild-type (WT) mitochondria, implicating AtGABP as a major mitochondrial GABA carrier. Measurements of CO2 release, derived from radiolabeled substrates in whole seedlings and in isolated mitochondria, demonstrate impaired GABA-derived input into the TCA cycle, and a compensatory increase in TCA cycle activity in gabp mutants. Finally, growth abnormalities of gabp mutants under limited carbon availability on artificial media, and in soil under low light intensity, combined with their metabolite profiles, suggest an important role for AtGABP in primary carbon metabolism and plant growth. Thus, AtGABP-mediated transport of GABA from the cytosol into mitochondria is important to ensure proper GABA-mediated respiration and carbon metabolism. This function is particularly essential for plant growth under conditions of limited carbon.