Light

The utilization of macromolecules in therapy of cancer and other diseases is becoming increasingly relevant. Recent advances in molecular biology and biotechnology have made it possible to improve targeting and design of cytotoxic agents, DNA complexes, and other macromolecules for clinical applications. To achieve the expected biological effect of these macromolecules, in many cases, internalization to the cell cytosol is crucial. At an intracellular level, the most fundamental obstruction for cytosolic release of the therapeutic molecule is the membrane-barrier of the endocytic vesicles. Photochemical internalization (PCI) is a novel technology for release of endocytosed macromolecules into the cytosol. The technology is based on the use of photosensitizers located in endocytic vesicles that upon activation by light induces a release of macromolecules from their compartmentalization in endocytic vesicles. PCI has been shown to potentiate the biological activity of a large variety of macromolecules and other molecules that do not readily penetrate the plasma membrane, including type I ribosome-inactivating proteins (RIPs), gene-encoding plasmids, adenovirus, oligonucleotides, and the chemotherapeutic bleomycin. PCI has also been shown to enhance the treatment effect of targeted therapeutic macromolecules. The present protocol describes PCI of an epidermal growth factor receptor (EGFR)-targeted protein toxin (Cetuximab-saporin) linked via streptavidin-biotin for screening of targeted toxins as well as PCI of nonviral polyplex-based gene therapy. Although describing in detail PCI of targeted protein toxins and DNA polyplexes, the methodology presented in these protocols are also applicable for PCI of other gene therapy vectors (e.g., viral vectors), peptide nucleic acids (PNA), small interfering RNA (siRNA), polymers, nanoparticles, and some chemotherapeutic agents.

OBJECTIVE: To assess the impact of laser peripheral iridotomy (LPI) on forward-scatter of light and subjective visual symptoms and to identify LPI parameters influencing these phenomena. DESIGN: Cohort study derived from a randomized trial, using an external control group. PARTICIPANTS: Chinese subjects initially aged 50 or older and 70 years or younger with bilateral narrow angles undergoing LPI in 1 eye selected at random, and age- and gender-matched controls. METHODS: Eighteen months after laser, LPI-treated subjects underwent digital iris photography and photogrammetry to characterize the size and location of the LPI, Lens Opacity Classification System III cataract grading, and measurement of retinal straylight (C-Quant; OCULUS, Wetzlar, Germany) in the treated and untreated eyes and completed a visual symptoms questionnaire. Controls answered the questionnaire and underwent straylight measurement and (in a random one-sixth sample) cataract grading. MAIN OUTCOME MEASURES: Retina...

It has been previously described that when a sample's particle size is determined using different sizing techniques, the results can differ considerably. The purpose of this study was to review several in-process techniques for particle size determination (Spatial Filtering Velocimetry, Focused Beam Reflectance Measurements, Photometric Stereo Imaging, and the Eyecon Ò technology) and compare them to well-known and widespread off-line reference methods (laser diffraction and sieve analysis). To start with, a theoretical explanation of the working mechanism behind each sizing technique is presented, and a comparison between them is established. Secondly, six batches of granules and pellets (i.e., spherical particles) having different sizes were measured using these techniques. The obtained size distributions and related D 10 , D 50 , and D 90 values were compared using the laser diffraction wet dispersion method as reference technique. As expected, each technique provided different size distributions with different D values. These dissimilarities were examined and explained considering the measurement principles behind each sizing technique. The particle property measured by each particle size analyzer (particle size or chord length) and how it is measured as well as the way in which size information is derived and calculated from this measured property and how results are presented (e.g., volume or mass distributions) are essential for the interpretation of the particle size data.

This paper reports on the use of cellulose paper simultaneously as electrolyte, separation of electrodes, and physical support of a rechargeable battery. The deposition on both faces of a paper sheet of metal or metal oxides thin layers with different electrochemical potentials, respectively as anode and cathode, such as Cu and Al, lead to an output voltage of 0.70 V and a current density that varies between 150 nA/cm 2 and 0.5 mA/cm 2 , subject to the paper composition, thickness and the degree of OH x species adsorbed in the paper matrix. The electrical output of the paper battery is independent of the electrodes thickness but strongly depends on the atmospheric relative humidity (RH), with a current density enhancement by more than 3 orders of magnitude when RH changes from 60% to 85%. Besides flexibility, low cost, low material consumption, environmental friendly, the power output of paper batteries can be adapted to the desired voltage-current needed, by proper integration. A 3-V prototype was fabricated to control the ON/OFF state of a paper transistor.

The maximum distance to which the secondary mirror can be moved with respect to its primary in a true Cassegrain telescope with limited image deterioration is found to be proportional to the fourth power of the focal ratio of the primary mirror. This limit is independent of all other parameters describing the system when the magnification of the secondary is greater than about 3.

Recruitment is essential for the maintenance of populations, but far more is typically known about the more easily-observed adult stages than their smaller, often microscopic early life-history counterparts. This discrepancy can be particularly problematic for populations of foundation species that create biogenic habitat for a multitude of other taxa, but are themselves prime candidates for exploitation, fragmentation, and loss, and therefore become the focus of restoration eVorts partly or fully dependent on recruitment. The purpose of this study was to improve ecological understanding for early life-history stages of the habitat-forming marine alga Cystoseira barbata (Stackhouse) C. Agardh (Fucales: Sargassaceae), member of a genus that has experienced considerable fragmentation and population decline on European coasts. Using experimental manipulations of water temperature, light intensity, and sediment accumulation, we observed that sediment virtually precluded recruitment of C. barbata, and greatly impacted the survival of recently settled germlings (up to »83% mortality). Stronger intensities of light facilitated the growth of germlings, including the capacity for »50% of them to outgrow detrimental sediment and survive. Temperature (10 vs. 16°C) had no eVect on early recruitment, survival, or growth. This information helps to identify likely causes and locations of recruitment failure, and by extension, the conditions needed (either naturally or through human intervention) to facilitate recruitment and possible habitat restoration. Ultimately, this knowledge can increase our capacity to predict population persistence and the likely success of restoration eVorts. Communicated by S. D. Connell.

It is shown that the Fraunhofer diffraction pattern of a tilted aperture screen can be interpreted as a ' monocular view of the Ewald sphere. Two of those patterns recorded at opposite tilting angles are used to give a stereoscopic impression of the Ewald sphere. Experimental results are shown, and the approximations involved are discussed.

Background: The bacterial luciferase (lux) gene cassette consists of five genes (luxCDABE) whose protein products synergistically generate bioluminescent light signals exclusive of supplementary substrate additions or exogenous manipulations. Historically expressible only in prokaryotes, the lux operon was re-synthesized through a process of multibicistronic, codon-optimization to demonstrate for the first time self-directed bioluminescence emission in a mammalian HEK293 cell line in vitro and in vivo. Methodology/Principal Findings: Autonomous in vitro light production was shown to be 12-fold greater than the observable background associated with untransfected control cells. The availability of reduced riboflavin phosphate (FMNH 2) was identified as the limiting bioluminescence substrate in the mammalian cell environment even after the addition of a constitutively expressed flavin reductase gene (frp) from Vibrio harveyi. FMNH 2 supplementation led to a 151fold increase in bioluminescence in cells expressing mammalian codon-optimized luxCDE and frp genes. When injected subcutaneously into nude mice, in vivo optical imaging permitted near instantaneous light detection that persisted independently for the 60 min length of the assay with negligible background. Conclusions/Significance: The speed, longevity, and self-sufficiency of lux expression in the mammalian cellular environment provides a viable and powerful alternative for real-time target visualization not currently offered by existing bioluminescent and fluorescent imaging technologies.

Geometric solids are used to simulate tree crowns and their shadows. If real tree crowns cannot be accurately modelled by standard geometric shapes, inaccurate estimates of shadow-pattern location can result. This error may cause substantial inaccuracies in subsequent calculations of tree shade effects on space heating and cooling costs, as well as in estimates of crown volume and leaf surface area. This study found no statistically significant difference between formula-and photoestimated tree crown profile areas when opengrown trees were assigned geometric shapes with a template in the field. Less than 10% mean difference was found between the measures for three crown shapes; parabaloids, vertical ellipsoids and horizontal ellipsoids,

The restoration of anterior teeth is a difficult task, even for an experienced operator. Currently there are many different ceramic systems that can be used to achieve highly esthetic results. These include metal-ceramics with porcelain margins, Dicor, In-Ceram, Cerestore, Hi-Ceram, IPS-Empress, Cerapearl, Optec, and CAD/CAM ceramics. While metal-ceramics have been used for more than four decades, the quest for a material that transmits and refracts light like a natural tooth has inspired research into all-ceramic restorations. The purpose of this paper is to briefly discuss the properties of each of the above-mentioned materials and clinically evaluate the optical behavior of: (1) metal-ceramic crowns with castings 2 mm short of the shoulder preparation and 360-degree porcelain margins; (2) In-Ceram Spinell restorations; and (3) IPS Empress restorations, and to compare these with metal-ceramic crowns with copings to the shoulder preparation and 180-degree porcelain margins. Light t...

An hybrid atomic force-scanning near-field optical microscope (AFM-SNOM) has been realized starting from a home-built AFM. The instrument uses a tetrahedral SiN tip for force and near field detection and is designed to provide, besides simple imaging, a full three-dimensional (3-D) mapping of force, friction and light intensity on the sample. High-resolution optical images of dielectric samples are presented together with curves describing the behavior of the collected optical intensity as a function of tip-object distance. AFM images and forcedistance curves are reported as well and are compared with those obtained from the optical channel. Subwavelength features of the samples can be easily appreciated in both kinds of images, and the refractive index of the object can be computed from the attenuation constant of the tunneling light detected by the tip, with the AFM curve providing a convenient way of detecting the contact point. The spatial resolution of this kind of measurement is far better than that obtainable with any other index-measuring device. Homogeneous glass samples as well as monomode channel waveguides were analyzed in our experiments. The refractive index of several different prisms, made either of BK7 (n = 1:519 at = 532 nm) or of SF58 (n = 1:932) glass, could be measured with our near-field technique. As for the channel waveguides, the accuracy of our measurements lets us detect their presence and lateral extension in the substrate but is not yet sufficient to allow the reconstruction of their index profile.

A nonlinear image technique for characterization of the optical nonlinearities is used to investigate the solid semiconductor ZnSe at 600 nm. The method based on a 4f nonlinear image technique with a phase object is used to obtain the diffraction pattern of the nonlinear filter in solid ZnSe located at the Fourier plane by a CCD camera. The nonlinear absorption coefficient and nonlinear refraction index were both obtained by fitting the nonlinear image. Good agreement between the experiment data and the simulated result are obtained indicating a sensitive and powerful method for nonlinear optical measurements.

A theory is presented which relates the minimum detectable contrast level for an object in the presence of noise to the statistics of the speckle. Consideration is given to smoothing of the noise by multiple looks and by area. Measurements of the minimum detectable contrast are made for two types of speckle noise. First, a coherent, plane wave is added to an ideal diffuse wave and the threshold of detection is established as a function of the beam ratio. Secondly, these results are compared to the technique of speckle smoothing using an N-fold intensity superposition of fully developed theory is observed.

We measure the spectrum of coherent Brillouin scattering (CBS) in a gas as a function of time and observe for the first time additional spectral sidebands and line shape narrowing of the Brillouin peak. We find that both effects result from the interference of the density modulation induced by the moving dipole force of the pump beams with the acoustic waves induced by their fast thermalization and are predicted by a hydrodynamic-light scattering model. These line shapes differ from both spontaneous and stimulated Brillouin scattering spectra and also from previous coherent Rayleigh-Brillouin measurements.

The influence of season, gender, and reproductive maturity on the sensory properties (appearance, odor, taste, flavor, texture/mouthfeel, and aftertaste) of roe from sea urchins (Evechinus chloroticus) was investigated. A trained sensory panel applied descriptive analysis, with a comprehensive sensory vocabulary of 35 descriptors to analyze sea urchin roe obtained from samples collected during the austral autumn, winter, summer, and spring, over a 2-y period. Sensory differences between genders were less pronounced in autumn (March to May) and winter (June to August) when more nutritive cells were present in the roe, and more pronounced over spring (September to November) and summer (December to February) months as the gametogenic cells matured. Roe from female sea urchins were commonly associated with sulfur odor, bitter taste, and metallic flavor, while roe from the male sea urchins were associated with sweet taste. During autumn, female roe were closest in sensory quality to male roe (least bitter and most sweet compared to other seasons), while there were little differences in sweetness and bitterness of male roe over the 4 seasons. Despite the relative size of the roe being lowest in autumn, it appeared to be the optimum season to harvest E. chloroticus sea urchins to obtain high-quality roe.

Using cDNA microarray analysis, we previously identified a set of differentially expressed genes in primary breast tumors based on the status of estrogen and progesterone receptors. In the present study, we performed an integrated computer-assisted and manual search of potential estrogen response element (ERE) binding sites in the promoter region of these genes to characterize their potential to be regulated by estrogen receptors (ER). Publicly available databases were used to annotate the position of these genes in the genome and to extract a 5'flanking region 2 kb upstream to 2 kb downstream of the transcription start site for transcription binding site analysis. The search for EREs and other binding sites was performed using several publicly available programs. Overall, approximately 40% of the genes analyzed were potentially able to be regulated by estrogen via ER. In addition, 17% of these genes are located very close to other genes organized in a head-to-head orientation with less than 1.0 kb between their transcript units, sharing a bidirectional promoter, and could be classified as bidirectional gene pairs. Using quantitative real-time PCR, we further investigated the effects of 17β-estradiol and antiestrogens on the expression of the bidirectional gene pairs in MCF-7 breast cancer cells. Our results showed that some of these gene pairs, such as TXNDC9/ EIF5B, GALNS/TRAPPC2L, and SERINC1/PKIB, are modulated by 17β-estradiol via ER in MCF-7 breast cancer cells. Here, we also characterize the promoter region of potential ER-regulated genes and provide new information on the transcriptional regulation of bidirectional gene pairs.

: The quantitative description of cell structures in light microscope images is an important task in biological research. The inclusion of digital image processing techniques and fluorescent markers into light microscope imaging has recently made this task feasible. In this paper, we present a method for detection of filamentary structures in cell images that have been highlighted with fluorescent markers. The method has three stages. First, pixels belonging to fiber contours are extracted from the image. Then these pixels are grouped together based on proximity by a minimal spanning tree. Finally, the fiber contours are determined as sub-trees of the minimal spanning tree. Once the pixels belonging to individual fibers contours have been determined, quantitative statistics describing the fibers in the cell can be calculated.

We determine temperature effect on the absorption and reduced scattering coefficients (a and s Ј) of human forearm skin. Optical and thermal simulation data suggest that a and s Ј are determined within a temperature-controlled depth of Ϸ2 mm. Cutaneous s Ј change linearly with temperature. Change in a was complex and irreversible above body normal temperatures. Light penetration depth (␦) in skin increased on cooling, with considerable person-toperson variations. We attribute the effect of temperature on s Ј to change in refractive index mismatch, and its effect on a to perfusion changes. The reversible temperature effect on s Ј was maintained during more than 90 min. contact between skin and the measuring probe, where temperature was modulated between 38 and 22°C for multiple cycles While temperature modulated s Ј instantaneously and reversibly, a exhibited slower response time and consistent drift. There was a statistically significant upward drift in a and a mostly downward drift in s Ј over the contact period. The drift in temperature-induced fractional change in s Ј was less statistically significant than the drift in s Ј. ⌬ s Ј values determined under temperature modulation conditions may have less nonspecific drift than s Ј which may have significance for noninvasive determination of analytes in human tissue.

Experimental and theoretical flux models have been developed to reveal the influence of sun flecks and increasing CO 2 concentrations on the energy and entropy balances of the leaf. The rapid and wide range of fluctuations in light intensity under field conditions were simulated in a climatic gas exchange chamber and we determined the energy and entropy balance of the leaf based on radiation and gas exchange measurements. It was estimated that the energy of photosynthetic active radiation (PAR) accounts for half of transpiration, which is the main factor responsible for the exportation of the entropy generated in photosynthesis (S g) out of the leaf in order to maintain functional the photosynthetic machinery. Although the response of net photosynthetic production to increasing concentrations of CO 2 under fluctuating light is similar to that under continuous light, rates of transpiration respond slowly to changes of light intensity and are barely affected by the concentration of CO 2 in the range of 260-495 ppm, in which net photosynthesis increases by more than 100%. The analysis of the results confirms that future increases of CO 2 will improve the efficiency of the conversion of radiant energy into biomass, but will not reduce the contribution of plant transpiration to the leaf thermal balance.

Recently, several theoretical papers have derived relationships for fiber-optic transmission system performance in terms of associated physical layer parameters. At the same time, a large number of detailed experiments have been and continue being performed that demonstrate increasing capacities and unregenerated reach. We use this wealth of experimental data to validate the aforementioned relationships, and to propose a set of simple scaling rules for performance. We find that, despite substantial differences in experimental configurations, overall performance in terms of spectral efficiency and unregenerated reach is well explained by scaling rules. These scaling rules will be useful to carriers seeking to understand what they should expect to see in terms of network performance using deployed or easily accessible technology, which may be radically different from hero experiment results. These rules will also be useful to design engineers seeking cost effective tradeoffs to achiev...

In the second half of the twentieth century, a new paradigm in food consumption emerged, expressed in the quest for low-calorie foods, with the objective of meeting new aesthetic standards, but also countering the development of overweight-related diseases.

Arrestins are members of a superfamily of proteins that arrest the activity of G-protein coupled receptors. Mouse cone photoreceptors express two visual arrestins, Arr1 and Arr4 (Carr). We quantified their expression levels and subcellular distributions in mouse cones: total Arr1 was estimated to be in an ~ 6:1 ratio to cone opsin, about 50-fold higher than Arr4. Recordings from single cones of Arr1 −/− and Arr4 −/− mice establish that both proteins are competent to arrest the activity of photoactivated S-and M-cone opsins. Recordings from Arr1 −/− , Arr4 −/− double-knockout mice establish a requirement for at least one of the two visual arrestins for normal cone opsin inactivation at all flash intensities. These recordings also reveal low activity photoproducts of S-and M-opsins that are absent when Grk1 and an arrestin are co-expressed, but which decay 70-fold more rapidly than the comparable photoproducts of rhodopsin in rods.

The objective of this study was to determine the relationship between light levels in the understory of a broadleaf forest and the content of six ginsenosides (Rg 1 , Re, Rb 1 , Rc, Rb 2, and Rd) in 1-and 2-year-old American ginseng (Panax quinquefolius L.) roots. Our results revealed that ginsenoside contents in 1-and 2 year-old roots collected in September were significantly related to direct and total light levels, and duration of sunflecks. At this time, the effect of light levels accounted for up to 48 and 62% of the variation in ginsenoside contents of 1-and 2-year-old American ginseng roots. Also, red (R) and far red (FR) light, and the R:FR ratio significantly affected Rd, Rc, and Rg 1 contents in 2-year-old roots, accounting for up to 40% of the variation in ginsenoside contents. Crown

Proper mixing of reagents is of paramount importance for an efficient chemical reaction. While on a large scale there are many good solutions for quantitative mixing of reagents, as of today, efficient and inexpensive fluid mixing in the nanoliter and microliter volume range is still a challenge. Complete, i.e., quantitative mixing is of special importance in any small-scale analytical application because the scarcity of analytes and the low volume of the reagents demand efficient utilization of all available reaction components. In this paper we demonstrate the design and fabrication of a novel centrifugal force-based unit for fast mixing of fluids in the nanoliter to microliter volume range. The device consists of a number of chambers ͑including two loading chambers, one pressure chamber, and one mixing chamber͒ that are connected through a network of microchannels, and is made by bonding a slab of polydimethylsiloxane ͑PDMS͒ to a glass slide. The PDMS slab was cast using a SU-8 master mold fabricated by a two-level photolithography process. This microfluidic mixer exploits centrifugal force and pneumatic pressure to reciprocate the flow of fluid samples in order to minimize the amount of sample and the time of mixing. The process of mixing was monitored by utilizing the planar laser induced fluorescence ͑PLIF͒ technique. A time series of high resolution images of the mixing chamber were analyzed for the spatial distribution of light intensities as the two fluids ͑suspension of red fluorescent particles and water͒ mixed. Histograms of the fluorescent emissions within the mixing chamber during different stages of the mixing process were created to quantify the level of mixing of the mixing fluids. The results suggest that quantitative mixing was achieved in less than 3 min. This device can be employed as a stand alone mixing unit or may be integrated into a disk-based microfluidic system where, in addition to mixing, several other sample preparation steps may be included. Physics 80, 075102-1 075102-2 Noroozi et al. Rev. Sci. Instrum. 80, 075102 ͑2009͒ 075102-3 Noroozi et al. Rev. Sci. Instrum. 80, 075102 ͑2009͒ 075102-5 Noroozi et al. Rev. Sci. Instrum. 80, 075102 ͑2009͒ 075102-6 Noroozi et al. Rev. Sci. Instrum. 80, 075102 ͑2009͒ 075102-7 Noroozi et al. Rev. Sci. Instrum. 80, 075102 ͑2009͒

SYNOPSIS. An age-autolyzed culture of Chroomonas salina, grown under cool-white light with glycerol, produced waxy lipid constituting about 44% of total matter harvested. This lipid was composed of 87% wax ester, 9% triglyceride, 3% polar lipid and 1% hydrocarbon. The major wax ester species were identified by total carbon number as C26(28%), C28(35%), C30(15%). The main fatty acid components of the wax esters were 12:0 (39%), 14:0 (30%), 16:0 (14%), while the main alcohols were 14:0 (53%) and 16:0 (40%). The hydrocarbon fraction showed saturated paraffins ranging from C17 to C33, with odd-numbered chain components predominating. No polyunsaturated components were detected in the wax ester or hydrocarbon fractions. This is the first record of wax ester production by a cryptomonad or a marine phytoplankter.

A theory of the influence of measurement conditions on temperature measurement accuracy with infrared systems has been recently presented. A comparison study of the shortwave 13-5-µm2 and longwave 18-12-µm2 measuring IR cameras was conducted on the basis of this theory. The results of the simulations show that the shortwave systems in typical measurement conditions generally offer better accuracy in temperature measurement than do the longwave systems. Some experiments that use a commercially available IR camera were carried out to verify the theory. The results of these experiments and a discussion about the theory limitations are presented.

The clinical performance of light polymerised dental composites is greatly in#uenced by the quality of the light-curing unit (LCU) used. Commonly used halogen LCUs have some speci"c drawbacks such as decreasing of the light output with time. This may result in low degree of monomer conversion of the composites with negative clinical implications. Previous studies have shown that blue-light-emitting diode (LED) LCUs have the potential to polymerise dental composites without having the drawbacks of halogen LCUs. Despite the relatively low irradiance of current LED LCUs, their e$ciency is close to that of conventional halogen LCUs with more than twice the irradiance. This phenomenon has not been explained fully yet. Hence, more tests of the LED LCU's e!ectiveness and of the mechanical properties of oral biomaterials processed with LED LCUs need to be carried out. This study investigates the #exural properties of three di!erent composites with three di!erent shades, which were polymerised with either a commercial halogen LCU or an LED LCU, respectively. In most cases no signi"cant di!erences in #exural strength and modulus between composites polymerised with a halogen LCU or an LED LCU, respectively, were found. A simple model for the curing e!ectiveness based on the convolution absorption spectrum of the camphorquinone photoinitiator present in composites and the emission spectra of the LCUs is presented.

Here we report the first crystal structure of the SH3 domain of the cellular Src tyrosine kinase (c-Src-SH3) domain on its own. In the crystal two molecules of c-Src-SH3 exchange their -RT loops generating an intertwined dimer, in which the two SH3 units, preserving the binding site configuration, are oriented to allow simultaneous binding of two ligand molecules. The dimerization of c-Src-SH3 is induced, both in the crystal and in solution, by the binding of a PEG molecule at the dimer interface, indicating that this type of conformations are energetically close to the native structure. These results have important implications respect to in vivo oligomerization and amyloid aggregation.

We investigated whether the degree of light inhibition of leaf respiration (R) differs among large Eucalyptus saligna grown in whole-tree chambers and exposed to present and future atmospheric [CO2] and summer drought. Associated with month-to-month changes in temperature were concomitant changes in R in the light (Rlight) and darkness (Rdark), with both processes being more temperature dependent in well-watered trees than under drought. Overall rates of Rlight and Rdark were not significantly affected by [CO2]. By contrast, overall rates of Rdark (averaged across both [CO2]) were ca. 25% lower under drought than in well-watered trees. During summer, the degree of light inhibition of leaf R was greater in droughted (ca. 80% inhibition) than well-watered trees (ca. 50% inhibition). Notwithstanding these treatment differences, an overall positive relationship was observed between Rlight and Rdark when data from all months/treatments were combined (R 2 = 0.8). Variations in Rlight were also positively correlated with rates of Rubisco activity and nitrogen concentration. Light inhibition resulted in a marked decrease in the proportion of light-saturated photosynthesis respired (i.e. reduced R/Asat). Collectively, these results highlight the need to account for light inhibition when assessing impacts of global change drivers on the carbon economy of tree canopies.

The molecular size of an outer surface protein from the photosynthetic bacterium Chlorobium tepidum was studied by dynamic light scattering (DLS) and HPLC gel filtration. For that purpose, the membrane protein was isolated and studied in four different nonionic surfactants, namely t-octylphenoxypolyethenoxyethanol (Triton X-100), (methyl-6-O-(N)-heptyl-carbamoyl)-a-D-glucopyranoside (Hecameg), dodecyl-h-D-maltoside (DDM) and n-octyl-oligo-oxyethylene (Octyl-POE). The protein was isolated by solubilization of the membranes with Triton X-100. The final purification step was a gel filtration, which was also used for surfactant exchange. Light scattering reveals the simultaneous presence of particles of different sizes in the 3 -6 and 20 -110 nm range, respectively. The smaller size is related to the hydrodynamic radius of the individual protein/surfactant complexes, whereas the larger size is associated with the presence of complex aggregates. D

In this study we report a systematic investigation of phthalocyanine (Pc) optical properties, showing that the effect of re-absorption of fluorescence plays a critical role in the line-shape of Pc optical spectra. We demonstrate that a strong dependence of the photoluminescence parameters on the concentration of phthalocyanines solution accounts for the apparent experimental evidence of a fluorescent dimer band in the emission at high concentrations. Despite a model based on fluorescent aggregates seems to describe the photophysical behavior of the system, additional experiments, such as electronic absorption spectroscopy, and fluorescence spectroscopy in which the optical pathlength inside the solution is suitably modified, provide a correct explanation of the observed optical behavior. We demonstrate that the shapes of optical spectra are completely independent on phthalocyanine aggregation state and are due only to experimental artifacts, i.e. inner filter effects.

Low-frequency ultrasound (LFUS) irradiation induces morphological, optical and surface changes in the commercial nano-TiO 2 -based photocatalyst, Evonik-Degussa P-25. Low-temperature electron spin resonance (ESR) measurements performed on this material provided the first experimental evidence for the formation of oxygen vacancies (V o ), which were also found responsible for the visible-light absorption. The V o surface defects might result from high-speed inter-particle collisions and shock waves generated by LFUS sonication impacting the TiO 2 particles. This is in contrast to a number of well-established technologies, where the formation of oxygen vacancies on the TiO 2 surface often requires harsh technological conditions and complicated procedures, such as annealing at high temperatures, radio-frequencyinduced plasma or ion sputtering.

To determine the relation between the corneal light transmission measurements and the epithelial surface properties in hen corneas after different refractive surgery techniques photorefractive keratectomy, laser in situ keratomileusis, and laser-assisted subepithelial keratomileusis, and a group with only epithelial corneal removal (deepithelialization). Methods. Five groups of hen corneas with different treatments and a control group were analyzed at 30 days. Direct transmittance and corneal light scattering were measured by a scatterometer developed by our group. Quantitative and systematic measurements of external and internal roughness and epithelium thickness were assessed using standard techniques developed for quantitative analysis of microphotographs of the corneal epithelium. Results. Data analysis revealed that the roughness in the epithelial surface was associated with the corneal light transmission. The direct transmittance of light showed a significant correlation with the epithelial roughness in the control (r ϭ Ϫ0.99, p Ͻ 0.05) and photorefractive keratectomy (r ϭ Ϫ0.99, p Ͻ 0.05) groups. However, there was no relation between the epithelial thickness and the corneal light transmission measurements. Conclusions. The experimental results suggested that the roughness of the epithelial surfaces is related to the light transmission in the cornea. (Optom Vis Sci 2010;87:1-•••)