Habitat degradation of Rhinopithecus bieti in Yunnan, China

Black-and-white snub-nosed monkeys (Rhinopithecus bieti) are endemic to the Trans-Himalayas in Northwest Yunnan and Southeast Tibet between the upper Yangtze and Mekong Rivers. Based on field surveys and previous reports, we identified the dark-coniferous forest, the mixed coniferous and broadleaf forest, and oak patches as suitable habitats (SH) for the monkeys. Summer grazing lands (SGL), which were made by local people cutting and burning the dark-coniferous forest at the high altitude belt, replaced SH. To have a general view of the status of the SH in Yunnan, we estimated the areas of SH and SGL from satellite images in 1997, and compared with areas estimated from aerial photo-based maps (ca. 1958). The work resulted in: 1) the area of SH was 4,169 km(2) in 1997; 2) SGL was 1,923 km(2); 3) during the past 40 years, the area of SH decreased by 31% (1,887 km(2)), and SGL increased by 204% (1,291 km(2)); and 4) the mean size of forest patches decreased from 15.6 to 5.4 km(2). In addition, the area of SGL is positively correlated to local human population (R-2 greater than or equal to0.53), implying that the reduction and fragmentation of habitat for Rhinopithecus bieti is a result of population growth of humans, who mostly employ traditional modes of production. Only 11 monkey groups remained in the changing habitat. Considering that forests at lower elevation were also encroached upon by farmlands in a similar way, the forest ecosystem is highly threatened. The destruction will continue unless there is a change in the mode of production in the region.

Sleeping sites of Rhinopithecus bieti at Mt. Fuhe, Yunnan

Data on sleeping site selection were collected for a group of black-and-white snub-nosed monkeys (Rhinopithecus bieti; around 80) at Mt. Fuhe, Yunnan, China (99degrees20'E, 26degrees25'N, about 3,000 m asl) from November 2000 to January 2002. At the site mainly three vegetation types were present in an elevation-ascending order: deciduous broad leaf forest, mixed coniferous and broad leaf forest, and dark coniferous forest. In addition, bamboo forest presented in areas burned in 1958. Sleeping sites (n = 10) were located in the coniferous forest, where trees were the tallest, bottommost branches were the highest, the diameter of crowns was the second largest, and the gradient of the ground was the steepest. Monkeys usually kept quiet during entering and staying at a sleeping site. The site choice and the quietness may be tactics to avoid potential predators. In the coniferous forest, however, monkeys did not sleep in the valley bottom where trees were the largest, but frequently slept in the middle of the slope towards the east/southeast, in the shadow of ridges in three other directions, to avoid strong wind and to access sunshine; in winter-spring, they ranged in a more southern and lower area than in summer-autumn. These may be behavioral strategies to minimize energy stress in the cold habitat. Monkeys often slept in the same sleeping site on consecutive nights, which reflected a reduced pressure of predation probably due to either the effectiveness of anti-predation through sleeping site selection, or the population decline of predators with increasing human activities in the habitat. The group's behavioral responses to interactive and sometimes conflicting traits of the habitat are site-specific and conform to expectations for a temperate zone primate.

Light-bias induced instability and persistent photoconductivity in In-Zn-O/Ga-In-Zn-O thin film transistors

Stress/recovery measurements demonstrate that even high-performance passivated In-Zn-O/ Ga-In-Zn-O thin film transistors with excellent in-dark stability suffer from light-bias induced threshold voltage shift (ΔV T) and defect density changes. Visible light stress leads to ionisation of oxygen vacancy sites, causing persistent photoconductivity. This makes the material act as though it was n-doped, always causing a negative threshold voltage shift under strong illumination, regardless of the magnitude and polarity of the gate bias.

P-16: Light-bias induced instability and persistent photoconductivity in in-zn-o/ga-in-zn-o thin film transistors

Stress/recovery measurements demonstrate that even highperformance passivated In-Zn-O/ Ga-In-Zn-O thin film transistors with excellent in-dark stability suffer from light-bias induced threshold voltage shift (ΔV T) and defect density changes. Visible light stress leads to ionisation of oxygen vacancy sites, causing persistent photoconductivity. This makes the material act as though it was n-doped, always causing a negative threshold voltage shift under strong illumination, regardless of the magnitude and polarity of the gate bias. © 2011 SID.

Near-ultraviolet zinc oxide nanowire sensor using low temperature hydrothermal growth.

Two near-ultraviolet (UV) sensors based on solution-grown zinc oxide (ZnO) nanowires (NWs) which are only sensitive to photo-excitation at or below 400 nm wavelength have been fabricated and characterized. Both devices keep all processing steps, including nanowire growth, under 100 °C for compatibility with a wide variety of substrates. The first device type uses a single optical lithography step process to allow simultaneous in situ horizontal NW growth from solution and creation of symmetric ohmic contacts to the nanowires. The second device type uses a two-mask optical lithography process to create asymmetric ohmic and Schottky contacts. For the symmetric ohmic contacts, at a voltage bias of 1 V across the device, we observed a 29-fold increase in current in comparison to dark current when the NWs were photo-excited by a 400 nm light-emitting diode (LED) at 0.15 mW cm(-2) with a relaxation time constant (τ) ranging from 50 to 555 s. For the asymmetric ohmic and Schottky contacts under 400 nm excitation, τ is measured between 0.5 and 1.4 s over varying time internals, which is ~2 orders of magnitude faster than the devices using symmetric ohmic contacts.

Cylindrical Fresnel lenses based on carbon nanotube forests

The forests of carbon nanotubes have been termed as the darkest man-made materials. Such materials exhibit near-perfect optical absorption (reflectance∼0.045%) due to low reflectance and nanoscale surface roughness. We have demonstrated the utilization of these perfectly absorbing forests to produce binary amplitude cylindrical Fresnel lenses. The opaque Fresnel zones are defined by the dark nanotube forests and these lenses display efficient focusing performance at optical wavelengths. Lensing performance was analyzed both computationally and experimentally with good agreement. Such nanostructure based lenses have many potential applications in devices like photovoltaic solar cells. © 2012 American Institute of Physics.

Thylakoid terminal oxidases are essential for the cyanobacterium Synechocystis sp. PCC 6803 to survive rapidly changing light intensities.

Cyanobacteria perform photosynthesis and respiration in the thylakoid membrane, suggesting that the two processes are interlinked. However, the role of the respiratory electron transfer chain under natural environmental conditions has not been established. Through targeted gene disruption, mutants of Synechocystis sp. PCC 6803 were generated that lacked combinations of the three terminal oxidases: the thylakoid membrane-localized cytochrome c oxidase (COX) and quinol oxidase (Cyd) and the cytoplasmic membrane-localized alternative respiratory terminal oxidase. All strains demonstrated similar growth under continuous moderate or high light or 12-h moderate-light/dark square-wave cycles. However, under 12-h high-light/dark square-wave cycles, the COX/Cyd mutant displayed impaired growth and was completely photobleached after approximately 2 d. In contrast, use of sinusoidal light/dark cycles to simulate natural diurnal conditions resulted in little photobleaching, although growth was slower. Under high-light/dark square-wave cycles, the COX/Cyd mutant suffered a significant loss of photosynthetic efficiency during dark periods, a greater level of oxidative stress, and reduced glycogen degradation compared with the wild type. The mutant was susceptible to photoinhibition under pulsing but not constant light. These findings confirm a role for thylakoid-localized terminal oxidases in efficient dark respiration, reduction of oxidative stress, and accommodation of sudden light changes, demonstrating the strong selective pressure to maintain linked photosynthetic and respiratory electron chains within the thylakoid membrane. To our knowledge, this study is the first to report a phenotypic difference in growth between terminal oxidase mutants and wild-type cells and highlights the need to examine mutant phenotypes under a range of conditions.

Durability and photo-electric characteristics of a mille-feuille structured amorphous selenium (a-Se)-arsenic selenide (As2Se3) multi-layered thin film

A mille-feuille structured amorphous selenium (a-Se)-arsenic selenide (As2Se3) multi-layered thin film and a mixed amorphous Se-As2Se3 film is compared from a durability perspective and photo-electric perspective. The former is durable to incident laser induced degradation after numerous laser scans and does not crystallise till 105 of annealing, both of which are improved properties from the mixed evaporated film. In terms of photo-electric properties, the ratio between the photocurrent and the dark current improved whereas the increase of the dark current was higher than that of As2Se3 due to the unique current path developed within the mille-feuille structure. Implementing this structure into various amorphous semiconductors may open up a new possibility towards structure-sensitive amorphous photoconductors. © 2013 Elsevier B.V.

Optically activated shutter using a photo-tunable short-pitch chiral nematic liquid crystal

We report the demonstration of an optically activated shutter based upon a short-pitch chiral nematic liquid crystal (LC) device sandwiched between crossed polarizers. This LC is comprised of photo-active chiral dopants. In the trans-state, the LC appears dark between crossed polarizers due to the very short pitch. As the pitch is extended through exposure to ultraviolet light, the device becomes transmissive reaching a maximum for a particular value of the pitch. As a result, it is possible to switch between the light and dark states by subjecting the device to visible light so as to cause a cis-trans photo-isomerisation. © 2013 AIP Publishing LLC.

Onychostoma virgulatum, a new species of cyprinid fish (Pisces: Teleostei) from southern Anhui Province, South China

Onychostoma virgulatum, new species, is described from the Qiupu River, a tributary on the Southern bank of the lower Yangtze River at Shitai County, southern Anhui Province, South China. It shares with O. fusiforme and O. meridionale the presence of a longitudinal dark brown stripe extending along the lateral line, a character separating them from all other congeners of the moderate-mouth group diagnosed by having a slightly arched or nearly transverse mouth opening (with the extremities slightly curved posteriorly), its width being equal to or slightly less than the width of head at this same point, and a short postlabial groove extending along half of the length of the lateral margin of the lower jaw. Onychostoma virgulatum differs from both in the presence of two pairs of barbels in adults, from O. fusiforme in the body depth, caudal-peduncle depth, and position of pelvic and anal fins, and from O. meridionale in the structure of the last simple dorsal-fin ray.

Influence of dew on biomass and photosystem II activity of cyanobacterial crusts in the Hopq Desert, northwest China

Dew is an important water source for desert organisms in semiarid and arid regions. Both field and laboratory experiments were conducted to investigate the possible roles of dew in growth of biomass and photosynthetic activity within cyanobacterial crust. The cyanobacteria, Microcoleus vaginatus Gom. and Scytonema javanicum (Kutz.) Born et Flah., were begun with stock cultures and sequential mass cultivations, and then the field experiment was performed by inoculating the inocula onto shifting sand for forming cyanobacterial crust during late summer and autumn of 2007 in Hopq Desert, northwest China. Measurements of dew amount and Chlorophyll a content were carried out in order to evaluate the changes in crust biomass following dew. Also, we determined the activity of photosystem II(PSII) within the crust in the laboratory by simulating the desiccation/rehydration process due to dew. Results showed that the average daily dew amount as measured by the cloth-plate method (CPM) was 0.154 mm during fifty-three days and that the crust biomass fluctuated from initial inoculation of 4.3 mu g Chlorophyll a cm(-2) sand to 5.8-7.3 mu g Chlorophyll a cm(-2) crust when dew acted as the sole water source, and reached a peak value of approximately 8.2 mu g Chlorophyll a cm(-2) crust owing to rainfalls. It indicated that there was a highly significant correlation between dew amounts and crust moistures (r = 0.897 or r = 0.882, all P < 0.0001), but not a significant correlation between dew and the biomass (r = 0.246 or r = 0.257, all P > 0.05), and thus concluded that dew might only play a relatively limited role in regulating the crust biomass. Correspondingly, we found that rains significantly facilitated biomass increase of the cyanobacterial crust. Results from the simulative experiment upon rehydration showed that approximately 80% of PSII activity could be achieved within about 50 min after rehydration in the dark and at 5 degrees C, and only about 20% of the activity was light-temperature dependent. This might mean that dew was crucial for cyanobacterial crust to rapidly activate photosynthetic activity during desiccation and rehydration despite low temperatures and weak light before dawn. It also showed in this study that the cyanobacterial crusts could receive and retain more dew than sand, which depended on microclimatic characteristics and soil properties of the crusts. It may be necessary for us to fully understanding the influence of dew on regulating the growth and activity of cyanobacterial crust, and to soundly evaluate the crust's potential application in fighting desertification because of the available water due to dew. (C) 2009 Published by Elsevier Ltd.

Impacts of CO2 enrichment on growth and photosynthesis in freshwater and marine diatoms

The physiological responses of Nitzschia palea Kutzing, a freshwater diatom, to elevated CO2 were investigated and compared with those of a marine diatom, Chaetoceros muelleri Lemmermann previously reported. Elevated CO2 concentration to 700 mu l/L increased the dissolved inorganic carbon (DIC) and lowered the pH in the cultures of N. palea, thus enhancing the growth by 4%-20% during the whole growth period. High CO2-grown N. palea cells showed lower levels of dark respiration rates and higher I (k) values. Light-saturated photosynthetic rates and photosynthetic efficiencies decreased in N. palea with the doubling CO2 concentration in airflow to the bottom of cultures, although the doubling CO2 concentration in airflow to the surface cultures had few effects on these two photosynthetic parameters. N. palea cells were found to be capable of using HCO3 (-) in addition to gaseous CO2, and the CO2 enrichment decreased their affinity for HCO3 (-) and CO2. Although doubled CO2 level would enhance the biomass of N. palea and C. muelleri to different extents, compared with the marine diatom, it had a significant effect on the specific growth rates of N. palea. In addition, the responses of photosynthetic parameters of N. palea to doubled CO2 concentration were almost opposite to those of C. muelleri.

alpha-tocopherol is essential for acquired chill-light tolerance in the cyanobacterium Synechocystis sp strain PCC 6803

Unlike Escherichia coli, the cyanobacterium Synechocystis sp. strain PCC 6803 is insensitive to chill (5 degrees C) in the dark but rapidly losses viability when exposed to chill in the light (100 mu mol photons m(-2) s(-1)). Preconditioning at a low temperature (15 degrees C) greatly enhances the chill-light tolerance of Synechocystis sp. strain PCC 6803. This phenomenon is called acquired chill-light tolerance (ACLT). Preconditioned wild-type cells maintained a substantially higher level of alpha-tocopherol after exposure to chill-light stress. Mutants unable to synthesize alpha-tocopherol, such as slr1736, slr1737, slr0089, and slr0090 mutants, almost completely lost ACLT. When exposed to chill without light, these mutants showed no or a slight difference from the wild type. When complemented, the slr0089 mutant regained its ACLT. Copper-regulated expression of slr0090 from P-petE controlled the level of et-tocopherol and ACLT. We conclude that alpha-tocopherol is essential for ACLT of Synechocystis sp. strain PCC 6803. The role of a-tocopherol in ACLT may be based largely on a nonantioxidant activity that is not possessed by other tocopherols or pathway intermediates.

Plasmonic silver nanoparticles for improved organic solar cells

In the present work we compare the performance of organic solar cells, based on the bulk heterojunction system of P3HT:PCBM when adequate silver nanoparticles (NPs) are incorporated in two distinct places among the device structure. Introduction of NPs on top of the transparent anode revealed better overall performance with an increased efficiency of 17%. Alternatively, placing the NPs on top of the active photovoltaic layer resulted to 25% higher photo-current generation albeit with inferior electrical characteristics (i.e series and shunt resistance). Our findings suggest that enhanced scattering to non-specular directions from NPs site is maximized when penetrating light meets the particles after the polymer blend, but even this mechanism is not sufficient enough to explain the enhanced short circuit current observed. A second mechanism should be feasible; that is plasmon enhancement which is more efficient in the case where NPs are in direct contact with the polymer blend. J-V characteristics measured in the dark showed that NPs placed on top of the ITO film act as enhanced hole conducting sites, as evident by the lower series resistance values in these cells, suggesting this mechanism as more significant in this case. © 2012 Elsevier B.V. All rights reserved.

Effects of buffer layer properties and annealing process on bulk heterojunction morphology and organic solar cell performance

The performance of polymer-fullerene bulk heterojunction (BHJ) solar cells is strongly dependent on the vertical distribution of the donor and acceptor regions within the BHJ layer. In this work, we investigate in detail the effect of the hole transport layer (HTL) physical properties and the thermal annealing on the BHJ morphology and the solar cell performance. For this purpose, we have prepared solar cells with four distinct formulations of poly(3,4- ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) buffer layers. The samples were subjected to thermal annealing, applied either before (pre-annealing) or after (post-annealing) the cathode metal deposition. The effect of the HTL and the annealing process on the BHJ ingredient distribution - namely, poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) - has been studied by spectroscopic ellipsometry and atomic force microscopy. The results revealed P3HT segregation at the top region of the films, which had a detrimental effect on all pre-annealed devices, whereas PCBM was found to accumulate at the bottom interface. This demixing process depends on the PEDOT:PSS surface energy; the more hydrophilic the surface the more profound is the vertical phase separation within the BHJ. At the same time those samples suffer from high recombination losses as evident from the analysis of the J-V measurements obtained in the dark. Our results underline the significant effect of the HTL-active and active-ETL (electron transport layer) interfacial composition that should be taken into account during the optimization of all polymer-fullerene solar cells. © 2012 The Royal Society of Chemistry.