Illumination Cycle Research Articles

Exponential growth and selection in self-replicating materials from DNA origami rafts.

Self-replication and evolution under selective pressure are inherent phenomena in life, and but few artificial systems exhibit these phenomena. We have designed a system of DNA origami rafts that exponentially replicates a seed pattern, doubling the copies in each diurnal-like cycle of temperature and ultraviolet illumination, producing more than 7 million copies in 24 cycles. We demonstrate environmental selection in growing populations by incorporating pH-sensitive binding in two subpopulations. In one species, pH-sensitive triplex DNA bonds enable parent-daughter templating, while in the second species, triplex binding inhibits the formation of duplex DNA templating. At pH 5.3, the replication rate of species I is ∼1.3-1.4 times faster than that of species II. At pH 7.8, the replication rates are reversed. When mixed together in the same vial, the progeny of species I replicate preferentially at pH 7.8; similarly at pH 5.3, the progeny of species II take over the system. This addressable selectivity should be adaptable to the selection and evolution of multi-component self-replicating materials in the nanoscopic-to-microscopic size range.

A four state parametric model for the kinetics of the non-photochemical quenching in Photosystem II

The phenomenon of non-photochemical quenching (NPQ) was studied in spinach chloroplasts using pulse amplitude modulated (PAM) fluorometry. We present a new analysis method which describes the observed fluorescence quantum yield as the sum of the product of four different states of PSII and their corresponding quantum yields. These four distinct states are PSII in the quenched or unquenched state, and with its reaction center either open or closed depending upon the reduction of the QA site. With this method we can describe the dynamics of the NPQ induction and recovery as well as quantify the percentage of photoinactivated RC throughout the measurement. We show that after one cycle of quenching followed by a period of recovery, approximately 8–9% of the RC are photoinactivated, after two cycles of illumination this number becomes 15-17%. The recovery from the quenching appeared with rates of (50s)−1 and (1h)−1. The new analysis method presented here is flexible, allowing it to be applied to any type of PAM fluorometry protocol. The method allows to quantitatively compare qualitatively different PAM curves on the basis of statistically relevant fitting parameters and to quantify quenching dynamics and photoinactivation. Moreover, the results presented here demonstrate that the analysis of a single PAM fluorometry quenching experiment can already provide information on the relative quantum yield of the four different states of PSII for the intact chloroplasts - something no other form of spectroscopy could provide in a single measurement.

A method to transfer an individual graphene flake to a target position with a precision of sub-micrometer**Project supported by the National Key Research and Development Program of China (No. 2016YFB0402404), the High-Tech Research and Development Program of China (Nos. 2013AA031401, 2015AA016902, 2015AA016904), and the National Natural Foundation of China (Nos. 61674136, 61176053, 61274069, 61435002).

Graphene field-effect transistors have been intensively studied. However, in order to fabricate devices with more complicated structures, such as the integration with waveguide and other two-dimensional materials, we need to transfer the exfoliated graphene samples to a target position. Due to the small area of exfoliated graphene and its random distribution, the transfer method requires rather high precision. In this paper, we systematically study a method to selectively transfer mechanically exfoliated graphene samples to a target position with a precision of sub-micrometer. To characterize the doping level of this method, we transfer graphene flakes to pre-patterned metal electrodes, forming graphene field-effect transistors. The hole doping of graphene is calculated to be 2.16 . In addition, we fabricate a waveguide-integrated multilayer graphene photodetector to demonstrate the viability and accuracy of this method. A photocurrent as high as 0.4 μA is obtained, corresponding to a photoresponsivity of 0.48 mA/W. The device performs uniformly in nine illumination cycles.

Self-Assembled Lead Halide Perovskite Nanocrystals in a Perovskite Matrix

Hybrid metal halide perovskite materials are produced with facile routes, but their morphology is sensitive to water, oxygen, temperature, and exposure to light. While phase separation and self-assembly of perovskite nanostructures have been demonstrated, the realization of controlled perovskite–perovskite heterostructures has been limited up to now. We demonstrate here the growth of stable CH3NH3PbI3–xBrx nanocrystals in a CH3NH3PbBr3 matrix. Optical emission from the nanocrystals can be reversibly activated upon illumination through a photobrightening process. Optical microscopy images show that nanocrystals are stable in time, through several illumination cycles. Ultrafast photoluminescence measurements imply that optical excitations are funneled from the matrix into the lower bandgap nanocrystals. Because the nanocrystals represent <2% of the materials volume, the local carrier concentration is higher in the nanocrystals than in the matrix, leading to an increase in the photoluminescence quantum yield...

Enhanced photocurrent production by the synergy of hematite nanowire-arrayed photoanode and bioengineered Shewanella oneidensis MR-1

Coupling the light-harvesting capabilities of semiconductors with the catalytic power of bacteria is a promising way to increase the efficiency of bioelectrochemical systems. Here, we reported the enhanced photocurrents produced by the synergy of hematite nanowire-arrayed photoanode and the bio-engineered Shewanella oneidensis MR-1 in a solar-assisted microbial photoelectrochemical system (solar MPS) under the visible light. To increase the supply of bioelectrons, the D-lactate transporter, SO1522, was overexpressed in the recombinant S. oneidensis (T-SO1522) that could digest D-lactate 61% faster than the wild-type S. oneidenesis. Without light illumination, the addition of either the wild-type or the recombinant S. oneidensis to the system did not induce any obvious increase in the current output. However, under one-sun illumination, the photocurrent of the abiotic control was 16±2 μA cm−2 at 0.8V vs. Ag/AgCl, and the addition of the wild-type S. oneidensis and the recombinant S. oneidensis increased the photocurrent to 70±6 and 95±8 μA cm−2, respectively, at 0.8V vs. Ag/AgCl. Moreover, the solar MPS with T-SO1522 presented quick and repeatable responses to the on/off illumination cycles, and had relatively stable photocurrent generation in the 273-h operation. Scanning electron microscope (SEM) images showed that the cell density on the hematite photoelectrode was similar between the recombinant and the wild-type S. oneidensis. These findings revealed the pronounced influence of metabolic rates on the light-to-electricity conversion in the complex photocatalyst-electricigen hybrid system, which is important to promote the development of the solar MPS for electricity production and wastewater treatment.

Live-cell super-resolution imaging of intrinsically fast moving flagellates*This article belongs to the special issue: Emerging Leaders, which features invited work from the best early-career researchers working within the scope of J Phys D. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Susanne Fenz was selected by the Editorial Board of J Phys D

Recent developments in super-resolution microscopy make it possible to resolve structures in biological cells at a spatial resolution of a few nm and observe dynamical processes with a temporal resolution of ms to μs. However, the optimal structural resolution requires repeated illumination cycles and is thus limited to chemically fixed cells. For live cell applications substantial improvement over classical Abbe-limited imaging can already be obtained in adherent or slow moving cells. Nonetheless, a large group of cells are fast moving and thus could not yet be addressed with live cell super-resolution microscopy. These include flagellate pathogens like African trypanosomes, the causative agents of sleeping sickness in humans and nagana in livestock.Here, we present an embedding method based on a in situ forming cytocompatible UV-crosslinked hydrogel. The fast cross-linking hydrogel immobilizes trypanosomes efficiently to allow microscopy on the nanoscale. We characterized both the trypanosomes and the hydrogel with respect to their autofluorescence properties and found them suitable for single-molecule fluorescence microscopy (SMFM). As a proof of principle, SMFM was applied to super-resolve a structure inside the living trypanosome. We present an image of a flagellar axoneme component recorded by using the intrinsic blinking behavior of eYFP.

Ultraviolet-ozone anode surface treatment and its effect on organic solar cells

The effect of ultraviolet (UV)-ozone-treated indium-tin oxide (ITO, anode) on the initial parameters and degradation in small-molecule organic solar cells (OSCs) with the structure of ITO/copper phthalocyanine (CuPc, donor)/fullerene (acceptor)/bathocuproine (cathode buffer)/Ag (cathode) was experimentally investigated. A UV-ozone exposure with a UV intensity of 13.5mW/cm2 on the ITO surface was examined. The results indicated that compared with OSCs with no UV exposure, the initial short-circuit current density and power-conversion efficiency ηp increased in the OSC by 20% and 13%, respectively, after 1min of UV-ozone exposure. A repeated illumination stress comprising 3s of illumination and 12s of darkness was imposed on OSCs in air. The UV-ozone-treated OSCs showed excellent durability under the repeated illumination stress. After 10min of UV-ozone exposure, the OSCs exhibited only an 8% decrease in ηp after 100 illumination cycles. However, with no UV exposure, ηp decreased by approximately 65%, and the OSCs developed strong S-shaped kinks in their current–voltage characteristics, suggesting an increase in series resistance at the ITO–CuPc interface. The UV-ozone treatment much reduces the carbon contaminants on the ITO surface and increases the clean surface with polar components of OH functional groups and negatively charged oxygen. This generates attractive force between ITO and CuPc film. The attractive force prevents further CuPc crystal disorder and void formation at the ITO/CuPc interface, and achieves the durability against the illumination stress.

Effect of light-dark cycles on hydrogen and poly-β-hydroxybutyrate production by a photoheterotrophic culture and Rhodobacter capsulatus using a dark fermentation effluent as substrate

A Rhodobacter capsulatus strain and a photoheterotrophic culture (IZT) were cultivated to produce hydrogen under different light-dark cycles. A dark fermentation effluent (DFE) was used as substrate. It was found that IZT culture had an average cumulative hydrogen production (Paccum H2) of 1300±43mLH2L−1 under continuous illumination and light-dark cycles of 30 or 60min. In contrast, R. capsulatus reduced its Paccum H2 by 20% under 30:30min light-dark cycles, but tripled its poly-β-hydroxybutyrate (PHB) content (308±2mgPHB gdw−1) compared to continuous illumination. The highest PHB content by IZT culture was 178±10mgPHB gdw−1 under 15:15min light-dark cycles. PCR-DGGE analysis revealed that the IZT culture was mainly composed of Rhodopseudomonas palustris identified with high nucleotide similarity (99%). The evaluated cultures might be used for hydrogen and PHB production. They might provide energy savings by using light-dark cycles and DFE valorization.

Abstract B081: Spatially-resolved, multiplexed (up to 800 plex) digital characterization of protein and mRNA abundance in FFPE tissue sections: Application to immuno-oncology

Abstract The Tumor Microenvironment (TME) has emerged as a key compartment that determines the overall effectiveness of cancer immunotherapy. Hence, it is very important to determine the abundance and location of key immune-regulators in the TME. Historically, standard immunohistochemistry (IHC) and immunofluorescence have been used to assess spatial heterogeneity of proteins and nucleic-acids in tissue slices. However, these techniques are inherently limited in utility because it has been difficult to quantify the abundance of multiple protein/nucleic-acids across a wide dynamic range. Here, we report the development and validation of a spatially-resolved protein and RNA detection platform with the potential to simultaneously quantify up to 800 targets with greater than 5 log10 of dynamic range from a single formalin-fixed paraffin-embedded (FFPE) slide. We demonstrate validation of this technology by characterization of a panel of immune proteins expressed in colorectal cancer samples, and we also demonstrate spatially resolved detection of RNA. In situ high-plex digital molecular profiling is enabled by the use of UV-photocleavable small indexing DNA-oligo tags that can be delivered to the target within the tissue via direct attachment to RNA binding probes or conjugation to primary antibodies and are quantified with the standard nCounter technology. A slide-mounted FFPE tissue section is bound with a multiplexed cocktail of oligo-labeled primary antibody or mRNA hybridization probes, and a microfluidic flow cell is attached to the slide. Low-plex (3 or 4 color fluorescence) visible wavelength probes are utilized to generate an overall view of the FFPE tissue slice morphology (e.g., nuclear staining probes, select antibody pairs such as anti-CD3 and anti-CD8). Using the visible wavelength morphology as a guide, regions of interest (ROI) in the tumor are identified (e.g., areas with tumor infiltrating leukocytes) and then sequentially illuminated with UV light to release the indexing-oligos off all the high-plex molecular profiling reagents. Using this approach and standard microscope instrumentation, the limits of detection enable near single cell resolution. Following each UV illumination cycle, the photocleaved indexing-oligos are released into the buffer-layer above the tissue slice, collected via microcapillary aspiration, and stored in an individual well of a microtiter-plate. The contents of each well can then be referenced back to the exact region of tumor that was illuminated by UV light. Oligos are then hybridized to the nCounter fluorescently labeled optical barcodes to permit ex-situ digital counting of as many as 800 different analytes localized within a single ROI in the tumor. As demonstration of the technology, simultaneous multiplexed detection of CD3, CD8, CD45R0, CD4, CD45, PD-1, PD-L1, Vista, TIM-3, B7-H3, Ki67 (plus additional key IO-targets) will be quantified from colorectal tumor biopsies using oligo-conjugated primary antibodies. Furthermore, we will demonstrate detection of key IO associated immune RNA targets using direct hybridization of oligo-labeled probes. The ability to measure DNA, RNA, and protein at up-to 800-plex from single slices of FFPE tissue may enable the discovery of key immune biomarkers in tumors and accelerate the development immunotherapy and their associated companion diagnostics. Citation Format: Dwayne Dunaway, Jaemyeong Jung, Chris Merritt, Isaac Sprague, Philippa Webster, Sarah Warren, Joseph Beechem. Spatially-resolved, multiplexed (up to 800 plex) digital characterization of protein and mRNA abundance in FFPE tissue sections: Application to immuno-oncology [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B081.

Fatigue behavior of planar CH3NH3PbI3 perovskite solar cells revealed by light on/off diurnal cycling

Long-term stability represents a major challenge for the commercial deployment of hybrid perovskite solar cells (PSCs). The stability of solar cells is commonly tested under continuous illumination over extended periods of time, for example, 1000h. We have found that such a method does not adequately reflect the long-term performance of perovskite solar cells under the diurnal solar irradiation cycles experienced in real-world applications. We report a new characterization protocol of multiple 12-h cycles of darkness and illumination, uncovering a unique ‘fatigue’ behavior of PSCs. The PSC efficiency was found to decrease to 50% or less of its maximum value after storage in the dark for 12h under open circuit conditions. The solar cell performance was capable of recovering to its maximum value in the subsequent 12-h illumination period, but the recovery rate slowed significantly with successive illumination/darkness cycles. This fatigue mechanism was strongly dependent on the cell temperature. The identification of this fatigue behavior renders our proposed characterization protocol an essential component of perovskite solar cell testing.

Degradation by ultra-violet light and its mechanism in organic solar cells

We experimentally investigate the optimum illumination wavelength range and the degradation mechanism by the ultra-violet (UV) light for small-molecule organic solar cells (OSCs) using various long-pass filters with different cutoff wavelengths λc. The OSC structure consists of an indium–tin–oxide (ITO, anode)/copper phthalocyanine (CuPc, donor)/fullerene (acceptor)/bathocuproine (buffer)/Ag (cathode). The initial power conversion efficiency ηp is not affected by the use of the long-pass filter with λc < 400 nm. As λc increases above 400 nm, the initial ηp decreases significantly accompanied by a significant decrease in the short-circuit current, since the total amount of light energy absorbed in the OSC is decreased. The degradation of the OSC is investigated by repeating 30 s cycles, each consisting of 3 s of illumination followed by 27 s in the dark. The curve of the current JL vs voltage V under illumination becomes strongly S-shaped at the 100th illumination cycle for λc < 400 nm, showing degradation. In contrast, for λc > 400 nm, no distinct degradation appears. Thus, the origin of the degradation is revealed to be UV light with wavelengths less than 400 nm. The degradation mechanism is attributed to the decrease in carrier transport efficiency at the interface between ITO and CuPc film. Reorganization of the CuPc crystal structure occurs in the near-surface region on ITO due probably to the heat generated by the UV light. This would deteriorate the electrical contact at the interface, resulting in an increase in series resistance there.

Abstract 1371: Spatially-resolved, multiplexed digital characterization of protein distribution and abundance in FFPE tissue sections

Abstract Intratumoral heterogeneity has emerged as a critical challenge to the implementation of targeted therapeutics. Historically, immunohistochemistry (IHC) has been used to assess spatial heterogeneity of proteins; however, it has been difficult to quantify protein abundance at high multiplex and wide dynamic range. Here, we report the development and validation of a spatially-resolved, antibody-based proteomic approach with a “barcoding-potential” to quantify up to 800 targets with 5.5 logs (base 10) of dynamic range in a single formalin-fixed paraffin-embedded (FFPE) slide. By labeling antibodies with photocleavable oligos which are recognized by NanoString® nCounter® fluorescent barcodes and subsequently exposing them to focused UV light, we have developed an nCounter assay capable of quantifying protein abundance in a predefined spatial region of a tissue section. Methods: A slide-mounted FFPE tissue section is bound with a multiplexed cocktail of primary antibody-oligo conjugates, and a microfluidic flow cell is attached to the slide. Using a simple modification of a standard microscope, regions of interest are identified by light or fluorescence microscopy and are sequentially illuminated with UV light to release the oligos. Following each illumination cycle, an eluent is collected and analyzed, resulting in digital counts that correspond to the abundance of each targeted protein in sequentially illuminated areas. We demonstrate a high degree of linearity (0.97 &amp;lt; R2 &amp;lt; 0.99) for the number of observed counts versus area of UV illumination, with current detection spatial resolution down to 100 μm x 100 μm, or approximately 100 cells. Application: FFPE slides from resected breast cancers are bound with an antibody cocktail (10+ plex, including HER2, EGFR, PR and others) and visualized by light microscopy. Regions of interest are identified, and oligo barcodes from those regions are released by UV illumination and digitally quantified by nCounter analysis. This enables multiplexed detection and comparison of proteins of interest from discrete regions within the tumor and adjacent normal tissue, enabling systematic interrogation of the heterogeneous tumor microenvironment. Conclusion: Application of this NanoString barcoded antibody platform to ongoing clinical studies is intended to elucidate novel responses to immunotherapy and other targeted therapies. Further development of this technology will enable the multiplexed analysis of up to 800 protein targets from a single FFPE section and facilitate detailed interrogation of spatial interactions within a tissue. The ability to measure DNA, RNA, and protein from FFPE tissue may enable the discovery of immune biomarkers in tumors and the development of companion diagnostics. Citation Format: Alessandra Cesano, Joseph Beechem, Philippa Webster, Chris Merritt, Jaemyeong Jung, Dwayne Dunaway, Gary Geiss, Sarah Warren, Gordon Mills. Spatially-resolved, multiplexed digital characterization of protein distribution and abundance in FFPE tissue sections. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1371.

Chitosan-based microparticles for immobilization of TiO2 nanoparticles and their application for photodegradation of textile dyes

The present paper deals with removal and photocatalytic degradation of the textile dyes by TiO2 nanoparticles immobilized onto chitosan-based microparticles. The microparticles composed of chitosan (Ch) and poly(methacrylic acid) (PMA) were fabricated for the first time by inverse suspension polymerization. They were utilized for colloidal TiO2 nanoparticles immobilization, synthetized by acidic hydrolysis of TiCl4. To evaluate the potential application of Ch/PMA/TiO2 microparticles for treatment of textile wastwaters, their photocatalytic activity was examined by degradation assessment of three different groups of anionic azo dyes in aqueous solutions under solar light simulating source. FTIR analysis revealed that Ch and PMA were incorporated in the polymer network. SEM and optical microscopy confirmed their spherical shape. Under illumination, Ch/PMA/TiO2 microparticles completely removed dyes C.I. Acid Orange 7, C.I. Acid Red 18, C.I. Acid Blue 113, C.I. Reactive Black 5, C.I. Direct Blue 78, while removal degree of C.I. Reactive Yellow 17 was 75%. It was found that pH had significant influence on the photocatalytic activity of Ch/PMA/TiO2 microparticles. Increase of solution pH from acidic to alkaline, lead to decrease in photodegradation rate of C.I. Acid Orange 7 during the first hours of illumination. After three illumination cycles, removal degree of C.I. Acid Orange 7 was maintained at remarkably high level (95% at pH 5.60 and 100% at pH 2.00 and 8.00), indicating that microparticles could be reused without significant loss of photocatalytic efficiency.

Visible-light-driven Fe2O3 nanoparticles/TiO2 array photoelectrode and its photoelectrochemical property

A Fe2O3 nanoparticles/TiO2 array composite photoelectrode was prepared by growing Fe2O3 nanoparticles on TiO2 nanorods array by a hydrothermal method. Different concentrations of iron precursors were studied and 0.04 mol/L (4F/T) was found to possess the optimal quality. The heterojunctions between Fe2O3/TiO2 were confirmed by scanning electron microscope, transmission electron microscope and X-ray photoelectron spectroscopy. The Fe2O3 nanoparticles/TiO2 array composite photoelectrode exhibited enhanced photoelectrochemical activity under visible light irradiation. Compared to a Fe2O3 nanoparticles film electrode, it exhibited five times higher enhanced photoelectrochemical activity. Moreover, the composite photoelectrode displayed good stability for PEC measurements from the transient photocurrents of ON/OFF illumination cycles. The enhanced activity may be ascribed to the superior charge transport ability of the TiO2 nanorods array, proved by electrochemical impedance spectroscopy and Mott–Schottky analysis.

Ferroelectric photovoltaic response to structural transformations in doped BiFeO3 derivative thin films

We report an investigation on crystallographic texturing, optical bandgap modulation and ferroelectric photovoltaic (FE-PV) response of semitransparent Au/BiFeO3 derivatives/Sn:In2O3 (ITO) thin film capacitors. Optimized A/B-site doping of respective Ce3+ and Mn2+ drives large-amplitude structural changes in BiFeO3 (BFO) films with partial tetragonal transformation and upsurge in extent of texture of (110) preferred orientation. Spin coated BFO, doped BiFe0.9Mn0.1O3, Bi0.88Ce0.12FeO3 and codoped Bi0.88Ce0.12Fe0.9Mn0.1O3 films of 350nm thickness on ITO coated corning glass exhibited optical transmittance of 65–80% in visible light range and revealed blue shift in optical band gap from 2.53 to 2.81eV due to splitting of t2g and eg orbital. Influence of single and co-doping on FE-PV response demonstrated crystallographic orientation and depolarizing field dependent behavior of short circuit current (JSC) and open circuit voltage (VOC). Current-voltage (J-V) characteristics of semitransparent Au/Bi0.88Ce0.12Fe0.9Mn0.1O3/ITO capacitors possessed large JON/JOFF ratio of approx. 104 at zero bias. Temporal dependence of photocurrent showed highly repeatable and stable response for consecutive ON/OFF cycles of illumination under solid state violet laser (405nm) of 160mW/cm2 intensity, a forward step towards non-destructive memory combining electronic and optical functionalities.

BiFeO3/BaTiO3 Multilayer Structures for Solar Energy Harvesting Application

Abstract The BiFeO3/BaTiO3 (BFO/BTO) multilayer structures with varying number of individual layers from two to seven were prepared using chemical solution deposition (CSD) technique towards the ferroelectric photovoltaic applications. The BFO/BTO multilayer structure with six stacking layers exhibited maximum value of Voc=1.80 V and JON/OFF=2.955×103 due to enhanced ferroelectric properties which is attributed to significant interface coupling between 6 stacking layers of BFO and BTO. Good retention and high stability of transient current response were observed over multiple cycles of light illumination (on and off) highlighting the potential of fabricated photovoltaic cell based on multilayer structure having six stacking layers of BiFeO3 and BaTiO3 towards the solar energy harvesting applications.

Un miniatore nella bottega degli Astrapas? Alcune osservazioni attorno alle immagini del Tolomeo Marciano gr. Z. 516 (904)

Between the end of the thirteenth century and the beginning of the fourteenth, Thessaloniki was a flourishing and cosmopolitan city: in this context was realized the Ptolemy Marc. gr. Z. 516 (904), then belonging to cardinal Basilios Bessarion and today preserved in the Marciana Library of Venice. Copied in Greek by a Frank named Andrea Teluntas, the manuscript contained also a cryptic cycle of illumination that once Italo Furlan defined as an ethic and philosophical Christian Weltanschauung.The paper focuses on the illuminated cycle contained in the Ptolemy Marc. gr. Z. 516 (904), analyzing its artistic and literary sources and providing also a stylistic reading of it.

Functionally integrated liquid crystalline photochromic triple block copolymer with locally light‐ and thermal‐controllable sub‐blocks

ABSTRACTPhotoorientation and reorientation processes induced by illumination of the samples with oppositely directed polarized light and by the thermal treatment were studied for the films of triblock copolymer pAzo10‐b‐pPhM80‐b‐pAzo10 consisting of a nematic phenyl benzoate сentral sub‐block (PhM, DP = 80) with two terminal smectic azobenzene sub‐blocks (Azo, DP = 10). For amorphized films of triblock copolymer, illumination with polarized light (λ = 546 nm) is shown to be by orientation of only Azo‐containing groups, but upon following annealing of the film, PhM groups are adjusted to the orientation of Azo fragments. It was found, that the subsequent illumination of the block copolymer sample with oppositely directed polarized light changes the orientation of azobenzene groups, while the orientation of phenyl benzoate groups is remained unchanged. Thus, the cyclic illumination of the triblock copolymer samples by the linear polarized light and subsequent thermal treatment make it possible to control and fix orientation of azobenzene and phenyl benzoate groups located in different sub‐blocks in the desired and independent manner. The comparison of these results with the data on random p(Azo7‐ran‐PhM30) copolymer of the similar composition revealed, that in the random copolymer, both Azo and PhM mesogenic groups are involved in the orientational cooperative process regardless of films process treatment. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1602–1611

Effects of Aqueous Extract of Saffron on Gamma-Amino Butyric Acid Content in Rat Hypothalami

Background: Preliminary studies revealed that 4-aminobutyric acid (GABA) is a key and major inhibitory neurotransmitter in the brain. Evidence from many animal studies and even some clinical studies indicate that GABA is responsible for regulating behavior and also plays an important role in brain functions. Previous studies presented Glutamic acid decarboxylase as a catalyst for the conversion of glutamic acid to GABA. Objectives: The aim of this study was to evaluate the effects of saffron on GABA content in the hypothalamus of rats. Materials and Methods: Male rats weighing 190 - 210 g were used. They were maintained in a temperature-controlled room with a 12-hour light/dark illumination cycle. The rats were fed standard pellet feed and had access to water ad libitum. The animals were divided into three groups: The first group received a 250 L intraperitoneal injection of 0.05 g/mL saffron (Group I). The second group received a 250 L intraperitoneal injection of 0.1 g/mL saffron (Group II). The third group acted as the control and received only water (Group III). The time intervals chosen for this experiment were 1, 2, 4, and 8 weeks following the administration of saffron. At least six animals were assigned to each experimental group. At each time interval, the animals were anaesthetized and brain tissue extracted, hypothalami separated and homogenized in PBS solution, rinsed with PBS, re-filtered, and centrifuged at 1200 g for 10 minutes. Results: In this study, both doses of saffron (0.05g/mL[Group I];and0.1g/mL[Group II]) caused significantly increasedGABAcontent in each hypothalamus. GABA in Group I increased significantly compared to the control group (1.00 0.05 [mean  SD, n = 8] vs. 0.29  0.05, mM). GABA in Group II also increased significantly compared to the control group (1.45  0.07 [mean  SD, n = 8] vs. 0.290.05, mM). The effect of saffron on GABA was also dose dependent; the only exception occurring during the final time interval for the 0.1 g/mL saffron concentration. Conclusions: The results of this study demonstrated a significant increase in hypothalamus GABA content from saffron administration. One explanation for this observation could be the stimulation of glutamic acid decarboxylase the primary enzymeresponsible for the production of GABA. Saffron may be a potential therapeutic agent for improving neurotransmitter levels.

Circadian rhythm in locomotor activity in the burrower crayfish Procambarus acanthophorus (Villalobos 1948)

Crayfish Procambarus acanthophorus is a burrower that spends long periods building deep tunnels to reach the water table during the dry season; thus, its survival entertains a close ecological relationship with the sediment. The aim of this work was to determine whether the properties of the circadian rhythm of locomotor activity could be modified by the sediment availability. Experiments were conducted in both aquaria filled with sediment or filled with water, under cycles of Bright and Dim Illumination (BI:DI, 12:12 h) or under continuous DI:DI. The rhythm of locomotor activity was entrained with the photoperiod in aquaria with sediment or water; however, statistical differences between conditions were obtained comparing the period and the level of activity under free-running. These data suggest that the substrate’s sensorial perception could be encoded as a significant ecological parameter that exerts influence in the physiological mechanisms that control the temporal order in P. acanthophorus.