Complex Interplay between Absorber Composition and Alkali Doping in High‐Efficiency Kesterite Solar Cells

Sodium treatment of kesterite layers is a widely used and efficient method to boost solar cell efficiency. However, first experiments employing other alkali elements cause confusion as reported results contradict each other. In this comprehensive investigation, the effects of absorber composition, alkali element, and concentration on optoelectronic properties and device performance are investigated. Experimental results show that in the row Li–Na–K–Rb–Cs the nominal Sn content should be reduced by more than 20% (relative) to achieve the highest conversion efficiency. The alkali concentration resulting in highest device efficiencies is lower by an order of magnitude for the heavy alkali elements (Rb, Cs) compared to the lighter ones (Li, Na, K). Utilization of a wide range of characterization techniques helps to unveil the complex interplay between absorber composition and alkali doping. A ranking of alkali for best device performances, when employing alkali treatment, resulted in the order of Li > Na > K > Rb > Cs based on the statistics of more than 700 individual cells. Finally, a champion device with 11.5% efficiency (12.3% active area) is achieved using a high Li concentration with an optimized Sn content.     

The Interplay of Oxygen Functional Groups and Folded Texture in Densified Graphene Electrodes for Compact Sodium‐Ion Capacitors

Sodium‐ion capacitors (SICs) can effectively combine high energy density with high power density, and are especially appropriate for high‐power demanding applications of large‐scale stationary energy storage. Surface‐induced pseudocapacitive charge storage based on porous or nano carbon materials is regarded as the most promising candidate for SICs. Unfortunately, their ultralow packing densities severely restrict their practical applications. A novel approach toward ultrafast high‐volumetric SICs based on folded‐graphene electrodes has already been demonstrated and showed quite competitive performance. In this work, it is further proved that oxygen functional groups and folded texture are two key elements for high‐volumetric sodium storage of folded‐graphene electrodes. Through a simple and controllable method, of thermal treatment in inert atmosphere, both the oxygen functional groups and folded texture can be quantitatively manipulated to better investigate the individual contribution and mutual interplay. It is illustrated that oxygen functional groups are crucial to superior capacitive sodium storage while folded texture is not only the origin for high‐volumetric sodium storage but also beneficial for both capacitive and additional diffusion‐controlled sodium storage. Inspired by above‐mentioned conclusion, more rational designs and effective preparation of advanced structure and novel materials can be realized to better promote the development of high‐volumetric SICs.     

光氧化胁迫条件下叶绿体中活性氧的产生、清除及防御

活性氧(ROS)具有双重作用,高浓度引起细胞损伤,低浓度起保护作用。在光氧化胁迫条件下,光合作用高能态的反应与O2丰富供应使叶绿体成为活性氧丰富的来源。当ROS的积累超过抗氧化剂防护系统清除能力,叶绿体及细胞不可逆的光氧化损伤就会出现。而高等植物的质粒是半自主的细胞器,有它们自己的基因组学及转录、翻译机制来控制ROS生成、保护光合作用机构免受光氧化损伤。因此,本文就光氧化胁迫期间,叶绿体中ROS的乍成、功能与防护机制进行了综述。     

Depth perception in disparity-defined objects: finding the balance between averaging and segregation

Deciding what constitutes an object, and what background, is an essential task for the visual system. This presents a conundrum: averaging over the visual scene is required to obtain a precise signal for object segregation, but segregation is required to define the region over which averaging should take place. Depth, obtained via binocular disparity (the differences between two eyes’ views), could help with segregation by enabling identification of object and background via differences in depth. Here, we explore depth perception in disparity-defined objects. We show that a simple object segregation rule, followed by averaging over that segregated area, can account for depth estimation errors. To do this, we compared objects with smoothly varying depth edges to those with sharp depth edges, and found that perceived peak depth was reduced for the former. A computational model used a rule based on object shape to segregate and average over a central portion of the object, and was able to emulate the reduction in perceived depth. We also demonstrated that the segregated area is not predefined but is dependent on the object shape. We discuss how this segregation strategy could be employed by animals seeking to deter binocular predators.This article is part of the themed issue ‘Vision in our three-dimensional world’.     

Relationship between Protein Composition and Coagulation Reactivity,Particulate Formation,and Incorporation of Lipids in Soymilk

Many studies have suggested that the 11S/7S ratio in soybeans affects the coagulation reaction at the first step. In this study, the 11S/7S ratio in soybeans showed significantly negative correlation with MgCl₂ concentrations for the maximum breaking stress of tofu for six Japanese varieties. To determine the effect of the 11S/7S ratio, soymilk was fractionated by centrifugation after the addition of MgCl₂, and the distribution of lipids and proteins was studied. The amount of precipitate increased as the MgCl₂ concentration or the 11S/7S ratio increased. More triglyceride was incorporated into the precipitate as the MgCl₂ concentration or the 11S/7S ratio increased. The stain intensity of bands after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS–PAGE) indicated that the ratio of oleosin, a membrane protein of the oil body, increased in the precipitate as the MgCl₂ concentration or the 11S/7S ratio increased, while the ratios of glycinin and β-conglycinin were less variable. These results indicate that the 11S/7S ratio and coagulant concentration may have an effect on the amount of coagulum and the concentration of oil globules in the coagulum at the beginning of coagulation.     

Sodium nitroprusside toxicity in Drosophila melanogaster: delayed pupation, reduced adult emergence, and induced oxidative/nitrosative stress in eclosed flies

The toxicity of sodium nitroprusside (SNP) was tested on the Drosophila melanogaster model system. Fly larvae were raised on food supplemented with SNP at concentrations of 0.01-1.5 mM. Food supplementation with SNP caused a developmental delay in flies and reduced adult eclosion. Biochemical analyses such as levels of oxidative stress markers and activities of antioxidant and associated enzymes were carried out on 2-day-old flies emerged from control and SNP-fed larvae. Larval exposure to SNP resulted in lower activities of aconitase and catalase in adult flies relative to the control cohort. However, larval treatment with SNP led to higher carbonyl protein content and higher activities of superoxide dismutase, glucose-6-phosphate dehydrogenase, thioredoxin reductase, and glutathione-S-transferase in flies. Among the parameters tested, aconitase activity and developmental end points may be useful early indicators of toxicity caused by SNP. The study also suggests that the toxicity of SNP may arise not just from its direct effects, but also from its decomposition products such as nitric oxide and iron ions.     

香蕉不同成熟度果实活性氧、乙烯与淀粉酶活性相关性研究

采用各种活性氧诱发剂(0.5g/L百草枯、10mmol/L H₂O₂和10mmol/L H₂O₂+10mmol/L FeSO₄·7H₂O)及相应的清除剂(20mmol/L没食子酸丙酯、10个单位CAT和70mmol/L DMSO)、外源乙烯(750μl/L乙烯利)、乙烯生成先导物(合成前体,1mmol/L ACC)和乙烯合成抑制剂(10mmol/L AOA)处理香蕉果肉切片。结果表明,在不同成熟度的香蕉果实中,只有O₂^·存在及乙烯合成不受抑制时,淀粉酶活性才能呈现,果实才能软化、成熟;而O₂^·及OH^·可能在乙烯合成中所起的作用有所不同。     

Sodium and potassium transport to the xylem are inherited independently in rice, and the mechanism of sodium: potassium selectivity differs between rice and wheat

The heritability of sodium and potassium transport to the xylem was measured by the regression of F_n+1, on F_n means in two segregating breeding populations of rice (Oryza sativa L.). The narrow-sense heritabilities of shoot sodium concentration were 0.42 and 0.43 in the two populations, respectively, and the corresponding values for the heritability of shoot potassium concentration were 0.46 and 0.52. The sodium: potassium ratio was apparently heritable (0.36 and 0.40) because it was regressed positively on sodium concentration and negatively on potassium concentration. There was no significant relationship between the shoot sodium and potassium concentrations themselves. It is concluded that sodium and potassium uptake in rice are controlled by different genes which segregate independently. The magnitude of the transpirational bypass flow was estimated to be some 10 times greater in rice than in wheat (Triticum aestivum L.) and was found to be highly correlated with sodium uptake in rice but not in wheat. It is concluded that the bypass flow provides an additional pathway for sodium uptake in rice and that this accounts for the functional and genetic independence of sodium and potassium uptake in rice and consequently for the lesser prominence of potassium:sodium discrimination in rice than in wheat.     

Reaeration of Oxygen in Shallow,Macrophyte Rich Streams: II. Relationship between the Reaeration Rate Coefficient and Hydraulic Properties

The rate coefficient K₂ of the physical exchange of oxygen between flowing water and the atmosphere is dependent on water temperature and the hydraulic variables: mean velocity of flow U, mean depth H, and slope S of the stream channel. 36 equations from the literature predicting K₂ on basis of combinations of U, H and S have been tested against 144 corresponding measurements of K₂ and hydraulic variables taken in 10 reaches in 6 Danish streams with different development of the submerged macrophyte community. A statistical analysis showed that all equations except one had to be rejected. To improve predictive accuracy an equation K₂ (20 °C) = 8784 U^0.734H^−0.420 S^0.930 was developed applying multiple linear regression. This equation allows K₂-predictions for streams where the hydraulic variables U range from 0.06 to 0.52 m s⁻¹, H from 0.12 to 1.37 m and S from 0.3 to 7.4 × 10⁻³ m m⁻¹, respectively. Using this equation the lower and upper 95 % limit of confidence for a given K₂-prediction (K_2p) are K_2p/1.95 and K_2p × 1.95, indicating that such equations at best approximate the real K₂. Therefore K₂ should preferably be measured.     

Representing Statistical Distributions for Uncertain Parameters in LCA. Relationships between mathematical forms,their representation in EcoSpold,and their representation in CMLCA (7 pp)

Introduction Statistical information for LCA is increasingly becoming available in databases. At the same time, processing of statistical information is increasingly becoming easier by software for LCA. A practical problem is that there is no unique unambiguous representation for statistical distributions.- Representations. This paper discusses the most frequently encountered statistical distributions, their representation in mathematical statistics, EcoSpold and CMLCA, and the relationships between these representations.- The distributions. Four statistical distributions are discussed: uniform, triangular, normal and lognormal.- Software and examples. An easy to use software tool is available for supporting the conversion steps. Its use is illustrated with a simple example.Discussion This paper shows which ambiguities exist for specifying statistical distributions, and which complications can arise when uncertainty information is transferred from a database to an LCA program. This calls for a more extensive standardization of the vocabulary and symbols to express such information. We invite suppliers of software and databases to provide their parameter representations in a clear and unambiguous way and hope that a future revision of the ISO/TS 14048 document will standardize representation and terminology for statistical information.     

Sodium fluxes in corn roots: comparison to Cl and K fluxes, and to Na-fluxes in barley

Abstract. Carbonylcyanide, m -chlorophenyl hydra-zone (CCCP) decreased the ATP content of barley and corn roots by 80% within 5 min. The protonophore inhibited K and Cl absorption by largely unvacuolated root tips, and vacuolated root segments of barley and corn. The protonophore also inhibited Na absorption by root segments and Na extrusion by root tips of barley; it did not affect these Na fluxes in corn root tips and segments, and Na Influx in barley root tips. It was concluded that corn roots lack a metabolic mechanism for Na extrusion from the cytoplasm to the external solution or vacuole, which is functional in barley roots.     

Gas sensing in microplates with optodes: influence of oxygen exchange between sample, air, and plate material

Microplates with integrated optical oxygen sensors are a new tool to study metabolic rates and enzyme activities. Precise measurements are possible only if oxygen exchange between the sample and the environment is known. In this study we quantify gas exchange in plastic microplates. Dissolved oxygen was detected using either an oxygen-sensitive film fixed at the bottom of each well or a needle-type sensor. The diffusion of oxygen into wells sealed with different foils, paraffin oil, and paraffin wax, respectively, was quantified. Although foil covers showed the lowest oxygen permeability, they include an inevitable gas phase between sample and sealing and are difficult to manage. The use of oil was found to be critical due to the extensive shaking caused by movement of the plates during measurements in microplate readers. Thus, paraffin wax was the choice material because it avoids convection of the sample and is easy to handle. Furthermore, without shaking, significant gradients in pO2 levels within a single well of a polystyrene microplate covered with paraffin oil were detected with the needle-type sensor. Higher pO2 levels were obtained near the surface of the sample as well as near the wall of the well. A significant diffusion of oxygen through the plastic plate material was found using plates based on polystyrene. Thus, the location of a sensor element within the well has an effect on the measured pO2 level. Using a sensor film fixed on the bottom of a well or using a dissolved pO2-sensitive indicator results in pO2 offset and in apparently lower respiration rates or enzyme activities. Oxygen diffusion through a polystyrene microplate was simulated for measurements without convection--that is, for samples without oxygen diffusion through the cover and for unshaken measurements using permeable sealings. This mathematical model allows for calculation of the correct kinetic parameters.     

Oxygen consumption and ammonia excretion rates in Octopus maya,loligo forbesi and Lolliguncula brevis (Mollusca: Cephalopoda)

Oxygen consumption and ammonia excretion rates were investigated in young Octopus maya (hatching to 139 days old; 0.11–81.23 g wet body weight, BW; 22.5–23.9°C), young squids of Loligo forbesi (hatching to 45 days old; 9.4–115.3 mg BW; 12.3–13.1°C) and young squids of Lolliguncula brevis (2.00–39.98 g BW; 23.8–24.7°C). Except at hatching, oxygen consumption and ammonia excretion rates on an individual basis (M) of these three cephalopods increased linearly with increasing body weight (BW) expressed as M = aBW^b . Values of b for oxygen consumption were 0.900, 0.910 and 0.848 and for ammonia excretion were 0.744, 0.809 and 0.751 for O. maya, L. forbesi and L. brevis, respectively. Among the three species the value a varied widely, while b was similar for both oxygen consumption and ammonia excretion rates. Based upon these data, metabolism for hatchlings of O. maya and L. forbesi was estimated to be relatively lower than that of older juveniles. The O/N ratios for hatchlings of O. maya and L. forbesi were relatively high and indicate an apparent dependence upon lipids in the immediate post‐hatching period, followed by standard protein energy utilization thereafter.     

Interplay between various aspects in social relationships of young rhesus monkeys: Dominance,agonistic help,and affiliation

Relationships between group-living primates depend strongly on their position in the group dominance hierarchy and on their relationships with other group members. The influence of various behaviours on social relationships of immature rhesus monkeys (Macaca mulatta) was investigated here. Dominance ranks were established and related to the degree of affiliation in a dyad. Older monkeys were mostly dominant to the younger ones, regardless of kinship. Subordinate monkeys left proximity of their dominant members more often than they were left by them both among siblings and non-siblings, but the effect of dominance rank on the amount of play initiation and grooming in a dyad differed between these two types of dyads. The amount of agonistic help two individuals provided for each other was low among immatures. Nevertheless, pairs of siblings gave help to each other in agonistic conflicts more often than non-siblings, and such help was more often reciprocated between siblings than between non-siblings. Help in agonistic conflicts was positively correlated with the amount of time monkeys spent playing, grooming, or in proximity. Adults tended to interfere less in conflicts of frequent sibling play partners or non-sibling grooming partners. No evidence was found for young monkeys to exchange reciprocally grooming for agonistic help. It is argued that the time monkeys spend interacting with each other in affiliative interactions increases their familiarity and thus promotes close relationships between them. On the whole, young monkeys' relationships, like those between adults, are influenced strongly by their kinship, and position in the dominance hierarchy.     

The Role of Flower Inclination, Depth, and Height in the Preferences of a Pollinating Beetle (Coleoptera: Glaphyridae)

Amphicoma (Glaphyridae) beetles are important pollinators of red bowl-shaped flowers in the Mediterranean. The role of color and shape in flower choice is well studied but the roles of inclination, depth, and height have seldom been investigated. Under field conditions, models were used to experimentally manipulate these three characters and visitation rates of beetles were recorded. Models with red horizontal surfaces were visited significantly more often than models with red vertical surfaces. Shallow flower models were visited significantly more than deeper equivalents. Models below or at the height of natural flower populations elicited significantly more landings than models above the height of flowers. Inclination, depth, and height characteristics are all likely to be important components in the flower preferences exhibited by pollinating beetles.     

Clastogenic and Mutagenic Actions of Active Species Generated in the 6-Hydroxydopamine/Oxygen Reaction: Effects of Scavengers of Active Oxygen, Iron, and Metal Chelating Agents

A pro-oxidant triphenol, 6-hydroxydopamine (6-OHDA), induced mutations in the Salmonella typhimurium TA104 tester strain (over the concentration range to 800/JM), and induced chromosomal aberrations in cultured Chinese hamster ovary (CHO) cells at lower concentrations (up to 90 μM). It was however only marginally mutagenic (up to cytotoxic levels of 200 μM) in the TA102 tester strain. Clastogenicity in the more sensitive CHO cell assay was mediated by activated oxygen. Superoxide dismutase decreased the incidence of chromosomal aberrations by 60% and catalase (or superoxide dismutase plus catalase) decreased the incidence to control levels. The clastogenicity of 6-OHDA was dependent upon unsequestered transition metal ions, since addition of EDTA plus desferoxamine decreased chromosomal aberrations by 90%. The simplest explanation of the data is that genotoxicity is mediated by active species generated in a Fenton-type reaction between 6-OHDA and H₂O₂ catalyzed by traces of metals in the medium.     

Microbial colonisation of tannin-rich tropical plants: Interplay between degradability,methane production and tannin disappearance in the rumen

Condensed tannins in plants are found free and attached to protein and fibre but it is not known whether these fractions influence rumen degradation and microbial colonisation. This study explored the rumen degradation of tropical tannin-rich plants and the relationship between the disappearance of free and bound condensed tannin fractions and microbial communities colonising plant particles using in situ and in vitro experiments. Leaves from Calliandra calothyrsus, Gliricidia sepium, and Leucaena leucocephala, pods from Acacia nilotica and the leaves of two agricultural by-products: Manihot esculenta and Musa spp. were incubated in situ in the rumen of three dairy cows to determine their degradability for up to 96 h. Tannin disappearance was determined at 24 h of incubation, and adherent microbial communities were examined at 3 and 12 h of incubation using a metataxonomic approach. An in vitro approach was also used to assess the effects of these plants on rumen fermentation parameters. All plants contained more than 100 g/kg of condensed tannins with a large proportion (32–61%) bound to proteins. Calliandra calothyrsus had the highest concentration of condensed tannins at 361 g/kg, whereas Acacia nilotica was particularly rich in hydrolysable tannins (350 g/kg). Free condensed tannins from all plants completely disappeared after 24-h incubation in the rumen. Disappearance of protein-bound condensed tannins was variable with values ranging from 93% for Gliricidia sepium to 21% for Acacia nilotica. In contrast, fibre-bound condensed tannin disappearance averaged ～ 82% and did not vary between plants. Disappearance of bound fractions of condensed tannins was not associated with the degradability of plant fractions. The presence of tannins interfered with the microbial colonisation of plants. Each plant had distinct bacterial and archaeal communities after 3 and 12 h of incubation in the rumen and distinct protozoal communities at 3 h. Adherent communities in tannin-rich plants had a lower relative abundance of fibrolytic microbes, notably Fibrobacter spp. whereas, archaea diversity was reduced in high-tannin-containing Calliandra calothyrsus and Acacia nilotica at 12 h of incubation. Concurrently, in vitro methane production was lower for Calliandra calothyrsus, Acacia nilotica and Leucaena leucocephala although for the latter total volatile fatty acids production was not affected and was similar to control. Here, we show that the total amount of hydrolysable and condensed tannins contained in a plant govern the interaction with rumen microbes affecting degradability and fermentation. The effect of protein- and fibre-bound condensed tannins on degradability is less important.     

Biomass Characteristics,Aeration and Oxygen Transfer in Membrane Bioreactors: Their Interrelations Explained by a Review of Aerobic Biological Processes

Membrane bioreactor (MBR) is a promising alternative to conventional wastewater treatment methods. However this process is still under-used due to its high running costs. Its main power requirement comes from aeration, which is used to supply dissolved oxygen to the micro-organisms and to maintain the solids in suspension. In addition, in submerged MBRs, aeration is used for membrane cleaning. A complex matrix links the biomass characteristics, the aeration and the oxygen transfer. These parameters can impact on each other and/or delete one another effect. In order to understand the phenomena occurring in MBRs, similar aerobic biological processes, such as fermentation, mineral industry and slurry, were investigated. This review discusses the interrelations of the biomass characteristics (solids concentration, particle size and viscosity), the aeration intensity and the oxygen transfer in MBRs.