Effects of metal ion concentration on electrodeposited CuZnSn film and its application in kesterite Cu2ZnSnS4solar cells

In this study, effects of concentrations of Cu(II), Zn(II) and Sn(II) ions in the electrolytic bath solution on the properties of electrochemically deposited CuZnSn (CZT) films were investigated. Study of the composition of a CZT film has shown that the metallic content (relative atomic ratio) in the film increased linearly with increase in the metal ion concentration. It is the first time that the relationship of the compositions of the alloy phases in the co-electrodeposited CZT film with the concentration of metal ions has been revealed. The results have confirmed that the formation and content of Cu6Sn5 and Cu5Zn8 alloy phases in the film were directly controlled by the concentration of Cu(II). SEM measurements have shown that Sn(II) has significant impact on film morphology, which became more porous as a result of the larger nucleation size of tin. The changes in the surface properties of the films was also confirmed by chronoamperometry characteristic (i–t) deposition curves. By optimization of metal ion concentrations in the electrolyte solution, a copper-poor and zinc-rich kesterite Cu2ZnSnS4 (CZTS) film was synthesized by the sulfurization of the deposited CZT film. The solar cell with the CZTS film showed an energy conversion efficiency of 2.15% under the illumination intensity of 100 mW cm 2.

Wikipedia, collective authorship, and the politics of knowledge

This chapter considers the legal ramifications of Wikipedia, and other online media, such as the Encyclopedia of Life. Nathaniel Tkacz (2007) has observed: 'Wikipedia is an ideal entry-point from which to approach the shifting character of knowledge in contemporary society.' He observes: 'Scholarship on Wikipedia from computer science, history, philosophy, pedagogy and media studies has moved beyond speculation regarding its considerable potential, to the task of interpreting - and potentially intervening in - the significance of Wikipedia's impact' (Tkacz 2007). After an introduction, Part II considers the evolution and development of Wikipedia, and the legal troubles that have attended it. It also considers the establishment of rival online encyclopedia - such as Citizendium set up by Larry Sanger, the co-founder of Wikipedia; and Knol, the mysterious new project of Google. Part III explores the use of mass, collaborative authorship in the field of science. In particular, it looks at the development of the Encyclopedia of Life, which seeks to document the world's biodiversity. This chapter expresses concern that Wiki-based software had to develop in a largely hostile and inimical legal environment. It contends that copyright law and related fields of intellectual property need to be reformed in order better to accommodate users of copyright material (Rimmer 2007). This chapter makes a number of recommendations. First, there is a need to acknowledge and recognize forms of mass, collaborative production and consumption - not just individual authorship. Second, the view of a copyright 'work' and other subject matter as a complete and closed piece of cultural production also should be reconceptualised. Third, the defense of fair use should be expanded to accommodate a wide range of amateur, peer-to-peer production activities - not only in the United States, but in other jurisdictions as well. Fourth, the safe harbor protections accorded to Internet intermediaries, such as Wikipedia, should be strengthened. Fifth, there should be a defense in respect of the use of 'orphan works' - especially in cases of large-scale digitization. Sixth, the innovations of open source licensing should be expressly incorporated and entrenched within the formal framework of copyright laws. Finally, courts should craft judicial remedies to take into account concerns about political censorship and freedom of speech.

Re-thinking ancillary: Australian screen content in education

The use of Australian screen content in Australian schools and universities is undergoing rapid change due to digital and online distribution capacity on the supply side and digital and online affordance embedded in student cultures. This paper examines the ways in which Australian screen content and its distribution are beginning to adapt to educational usage. Issues facing content rights holders, distribution companies and emerging digital platforms reflect broad-based digital disruption patterns. Learning opportunities that can coincide with the growth in uptake of Australian screen content in Australia's education sector are not immune to the challenges posed by emerging digital consumption behaviours and issues of sustainability. At the same time, the growth in the use of digital and online screen content learning resources, under current copyright conditions, poses significant increases in the underlying cost structure for educational interests. This paper examines the innovations occurring in both the supply and the demand sides of Australian screen content and the expanded learning opportunities arising out of emerging digital affordances. Precedents in the UK are explored that demonstrate how stronger connections can be forged between nationally produced film and media content and a national curriculum. While addressing recent issues arising out of the Australian Law Review Commission's inquiry into copyright in the digital economy, the purpose of this discussion is not to assess policy debates about fair use versus fair dealing. What is clear, however, is that independent research is required that draws upon research-based evidence with an aim to better understanding the needs of the education sector against the transformative shifts taking place in digital-based learning materials and their modes of delivery.

In-vehicle filming of driver fatigue on YouTube: Vlogs, crashes and bad advice

Background: Driver fatigue contributes to 15-30% of crashes, however it is difficult to objectively measure. Fatigue mitigation relies on driver self-moderation, placing great importance on the necessity for road safety campaigns to engage with their audience. Popular self-archiving website YouTube.com is a relatively unused source of public perceptions. Method: A systematic YouTube.com search (videos uploaded 2/12/09 - 2/12/14) was conducted using driver fatigue related search terms. 442 relevant videos were identified. In-vehicle footage was separated for further analysis. Video reception was quantified in terms of number of views, likes, comments, dislikes and times duplicated. Qualitative analysis of comments was undertaken to identify key themes. Results: 4.2% (n=107) of relevant uploaded videos contained in-vehicle footage. Three types of videos were identified: (1) dashcam footage (n=82); (2) speaking directly to the camera - vlogs (n=16); (3) passengers filming drivers (n=9). Two distinct types of comments emerged, those directly relating to driver fatigue and those more broadly about the video or its uploader. Driver fatigue comments included: attribution of behaviour cause, emotion experienced when watching the video and personal advice on staying awake while driving. Discussion: In-vehicle footage related to driver fatigue is prevalent on YouTube.com and is actively engaged with by viewers. Comments were mixed in terms of criticism and sympathy for drivers. Willingness to share advice on staying awake suggests driver fatigue may be seen as a common yet controllable occurrence. This project provides new insight into driver fatigue perception, which may be considered by safety authorities when designing education campaigns.

Genetic and genomic studies of PADI4 in rheumatoid arthritis

Objectives. Strong genetic association of rheumatoid arthritis (RA) with PADI4 (peptidyl arginine deiminase) has previously been described in Japanese, although this was not confirmed in a subsequent study in the UK. We therefore undertook a further study of genetic association between PADI4 and RA in UK Caucasians and also studied expression of PADI4 in the peripheral blood of patients with RA. Methods. Seven single-nucleotide polymorphisms (SNP) were genotyped using polymerase chain reaction (PCR)-restriction fragment length polymorphism in 111 RA cases and controls. A marker significantly associated with RA (PADI4_100, rs#2240339) in this first data set (P = 0.03) was then tested for association in a larger group of 439 RA patients and 428 controls. PADI4 transcription was also assessed by real-time quantitative PCR using RNA extracted from peripheral blood mononuclear cells from 13 RA patients and 11 healthy controls. Results. A single SNP was weakly associated with RA (P = 0.03) in the initial case-control study, a single SNP (PADI4_100) and a two marker haplotype of that SNP and the neighbouring SNP (PADI4_04) were significantly associated with RA (P = 0.02 and P = 0.03 respectively). PADI4_100 was not associated with RA in a second sample set. PADI4 expression was four times greater in cases than controls (P = 0.004), but expression levels did not correlate with the levels of markers of inflammation. Conclusion. PADI4 is significantly overexpressed in the blood of RA patients but genetic variation within PADI4 is not a major risk factor for RA in Caucasians.

Dynamics of ribonuclease A and ribonuclease S: Computational and experimental studies

RNase S is a complex consisting of two proteolytic fragments of RNase A: the S peptide (residues 1-20) and S protein (residues 21-124). RNase S and RNase A have very similar X-ray structures and enzymatic activities. previous experiments have shown increased rates of hydrogen exchange and greater sensitivity to tryptic cleavage for RNase S relative to RNase A. It has therefore been asserted that the RNase S complex is considerably more dynamically flexible than RNase A. In the present study we examine the differences in the dynamics of RNaseS and RNase A computationally, by MD simulations, and experimentally, using trypsin cleavage as a probe of dynamics. The fluctuations around the average solution structure during the simulation were analyzed by measuring the RMS deviation in coordinates. No significant differences between RNase S and RNase A dynamics were observed in the simulations. We were able to account for the apparent discrepancy between simulation and experiment by a simple model, According to this model, the experimentally observed differences in dynamics can be quantitatively explained by the small amounts of free S peptide and S protein that are present in equilibrium with the RNase S complex. Thus, folded RNase A and the RNase S complex have identical dynamic behavior, despite the presence of a break in polypeptide chain between residues 20 and 21 in the latter molecule. This is in contrast to what has been widely believed for over 30 years about this important fragment complementation system.

Regolith mass balance inferred from combined mineralogical, geochemical and geophysical studies: Mule Hole gneissic watershed, South India

The aim of this study is to propose a method to assess the long-term chemical weathering mass balance for a regolith developed on a heterogeneous silicate substratum at the small experimental watershed scale by adopting a combined approach of geophysics, geochemistry and mineralogy. We initiated in 2003 a study of the steep climatic gradient and associated geomorphologic features of the edge of the rifted continental passive margin of the Karnataka Plateau, Peninsular India. In the transition sub-humid zone of this climatic gradient we have studied the pristine forested small watershed of Mule Hole (4.3 km(2)) mainly developed on gneissic substratum. Mineralogical, geochemical and geophysical investigations were carried out (i) in characteristic red soil profiles and (ii) in boreholes up to 60 m deep in order to take into account the effect of the weathering mantle roots. In addition, 12 Electrical Resistivity Tomography profiles (ERT), with an investigation depth of 30 m, were generated at the watershed scale to spatially characterize the information gathered in boreholes and soil profiles. The location of the ERT profiles is based on a previous electromagnetic survey, with an investigation depth of about 6 m. The soil cover thickness was inferred from the electromagnetic survey combined with a geological/pedological survey. Taking into account the parent rock heterogeneity, the degree of weathering of each of the regolith samples has been defined using both the mineralogical composition and the geochemical indices (Loss on Ignition, Weathering Index of Parker, Chemical Index of Alteration). Comparing these indices with electrical resistivity logs, it has been found that a value of 400 Ohm m delineates clearly the parent rocks and the weathered materials, Then the 12 inverted ERT profiles were constrained with this value after verifying the uncertainty due to the inversion procedure. Synthetic models based on the field data were used for this purpose. The estimated average regolith thickness at the watershed scale is 17.2 m, including 15.2 m of saprolite and 2 m of soil cover. Finally, using these estimations of the thicknesses, the long-term mass balance is calculated for the average gneiss-derived saprolite and red soil. In the saprolite, the open-system mass-transport function T indicates that all the major elements except Ca are depleted. The chlorite and biotite crystals, the chief sources for Mg (95%), Fe (84%), Mn (86%) and K (57%, biotite only), are the first to undergo weathering and the oligoclase crystals are relatively intact within the saprolite with a loss of only 18%. The Ca accumulation can be attributed to the precipitation of CaCO3 from the percolating solution due to the current and/or the paleoclimatic conditions. Overall, the most important losses occur for Si, Mg and Na with -286 x 10(6) mol/ha (62% of the total mass loss), -67 x 10(6) mol/ha (15% of the total mass loss) and -39 x 10(6) mol/ha (9% of the total mass loss), respectively. Al, Fe and K account for 7%, 4% and 3% of the total mass loss, respectively. In the red soil profiles, the open-system mass-transport functions point out that all major elements except Mn are depleted. Most of the oligoclase crystals have broken down with a loss of 90%. The most important losses occur for Si, Na and Mg with -55 x 10(6) mol/ha (47% of the total mass loss), -22 x 10(6) mol/ha (19% of the total mass loss) and -16 x 10(6) mol/ha (14% of the total mass loss), respectively. Ca, Al, K and Fe account for 8%, 6%, 4% and 2% of the total mass loss, respectively. Overall these findings confirm the immaturity of the saprolite at the watershed scale. The soil profiles are more evolved than saprolite but still contain primary minerals that can further undergo weathering and hence consume atmospheric CO2.

Variable-Temperature EPR and Transport Studies on Poly(4,4'-methylenedianiline): Evidence for Bipolarons

The correlation between magnetic and transport properties is examined by studying poly(4,4'-methylenedianiline)(PMDA) salts and their bases using EPR and conductivity measurements. Five different PMDA salts (doped polymers)were prepared by chemical polymerization of 4,4'-methylenedianiline using different protonic acids. The PMDA bases were obtained by dedoping the salts using ammonium hydroxide. Ambient temperature electrical conductivity measurements show evidence for the doped PMDA system to be highly disordered. The EPR spectra of the samples were recorded in the range 20-200 "C, and the results were analyzed on the basis of the polaron-bipolaron model, which is typical of nondegenerate systems. Both PMDA salts and their bases consist of self-trapped, highly mobile polarons or radical cations. EPR studies on PMDA salts show evidence for the presence of thermally activated and temperature independent (or Pauli type) paramagnetism while the bases show thermally activated, Pauli and Curie-Weiss types of paramagnetism. The paramagnetism arises due to polarons.It is proposed that charge transport takes place through both polarons and bipolarons.

Structural and functional studies of Bacillus stearothermophilus serine hydroxymethyltransferase: the role of Asn(341), Tyr(60) and Phe(351) in tetrahydrofolate binding

SHMT (serine hydoxymethyltransferase), a type I pyridoxal 5'-phosphate-dependent enzyme, catalyses the conversion of L-serine and THF (tetrahydrofolate) into glycine and 5,10-methylene THE SHMT also catalyses several THF-independent side reactions such as cleavage of P-hydroxy amino acids, trans-amination, racemization and decarboxylation. In the present study, the residues Asn(341), Tyr(60) and Phe(351), which are likely to influence THF binding, were mutated to alanine, alanine and glycine respectively, to elucidate the role of these residues in THF-dependent and -independent reactions catalysed by SHMT. The N341A and Y60A bsSHMT (Bacillus stearothermophilus SHMT) mutants were inactive for the THF-dependent activity, while the mutations had no effect on THF-independent activity. However, mutation of Phe(351) to glycine did not have any effect oil either of the activities. The crystal structures of the glycine binary complexes of the mutants showed that N341A bsSHMT forms an external aldimine as in bsSHMT, whereas Y60A and F351G bsSHMTs exist as a Mixture of internal/external aldimine and gem-diamine forms. Crystal structures of all of the three Mutants obtained in the presence of L-allo-threonine were similar to the respective glycine binary complexes. The structure of the ternary complex of F351G bsSHMT with glycine and FTHF (5-formyl THF) showed that the monoglutamate side chain of FTHF is ordered in both the subunits of the asymmetric unit, unlike in the wild-type bsSHMT. The present studies demonstrate that the residues Asn(341) and Tyr(60) are pivotal for the binding of THF/FTHF, whereas Phe(351) is responsible for the asymmetric binding of FTHF in the two subunits of the dimer.

Synthesis, structure and spectroscopic studies on hydroxo-bridged heterotrinuclear complexes of cobalt(m) with ethane-l,2-diamine and ammonia as terminal ligands

Hydroxo-bridged homo- and hetero-trinuclear cobalt(III) complexes of the type [MII(H2O)2{(OH)2CoIII(N4)}2]X2·nH2O [MII= a divalent metal ion such as CoII, NiII or ZnII; N4=(en)2(en = ethane-1,2-diamine) or (NH3)4; X = SO4 or (ClO4)2; n= 3 or 5] have been prepared and spectroscopically characterized. The structure of [Cu{(OH)2Co(en)2}2][SO4]2·2H2O 1 has been determined. The geometry around copper atom is a pseudo-square-based pyramid, with the basal sites occupied by four bridging hydroxide oxygens and the apical site is occupied by a weakly co-ordinated sulfate anion [Cu–O 2.516(4)Å]. The hydroxo groups bridge pairs of cobalt(III) ions which are in near-octahedral environments. The ethylenediamine chelate rings have the twist conformation. In the crystal structure of [Cu{(OH)2Co(en)2}2][ClO4]4·2H2O 2 the perchlorate ion is not co-ordinated and the en ligands have envelope conformations. The sulfate ion in [Cu{(OH)2Co(NH3)4}2][SO4]2·4H2O 3 is not co-ordinated to the central copper ion. Electronic, infrared and variable-temperature EPR spectral data are discussed.

Synthesis and magnetic studies of flower-like nickel nanocones

Flower-like nickel nanocone structures are synthesized by a simple chemical reduction method using hydrazine hydrate as the reducing agent. The structure, morphology and magnetic properties of as synthesized products are studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and SQUID magnetometer. The morphology evolution is studied by varying the reaction temperature and concentration of nickel chloride keeping other conditions unchanged.

Synthesis and magnetic studies of flower-like nickel nanocones

Flower-like nickel nanocone structures are synthesized by a simple chemical reduction method using hydrazine hydrate as the reducing agent. The structure, morphology and magnetic properties of as synthesized products are studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and SQUID magnetometer. The morphology evolution is studied by varying the reaction temperature and concentration of nickel chloride keeping other conditions unchanged.

High-Pressure Low-Temperature Locknut Cell For Both Electron-Paramagnetic-Res And Nmr-Studies To 10 Kilobars And 77-K

A locked high-pressure cell with working pressure range up to 10 kbars suitable for low-temperature studies to 77 K has been described. It can be used for both EPR and NMR studies of single crystals (and other solid samples). The high-pressure seal and all other aspects of the cell remain the same for either application. Only a change of the bottom plug is required for a switch from a nuclear-magnetic-resonance (NMR) to an electron-paramagnetic-resonance (EPR) experiment. Details of the procedure for the calibration of pressure inside the cell at various temperatures are discussed. The performance of the cell in EPR (Cr3+ion) and NMR (27Al nucleus) studies is reported.

Conformational analysis of small disulfide loops. Spectroscopic and theoretical studies on a synthetic cyclic tetrapeptide containing cystine

The conformational analysis of the synthetic peptide Boc-Cys-Pro-Val-Cys-NHMe has been carried out, as a model for small disulfide loops, in biologically active polypeptides. 'H NMR studies (270 MHz) establish that the Val(3) and Cys(4) NH groups are solvent shielded, while 13C studies establish an all-trans peptide backbone. Circular dichroism and Raman spectroscopy provide evidence for a right-handed twist of the disulfide bond. Analysis of the vicinal (JaB)c oupling constants for the two Cys residues establishes that XI - *60° for Cys(4), while some flexibility is suggested at Cys( 1). Conformational energy calculations, imposing intramolecular hydrogen bonding constraints, favor a P-turn (type I) structure with Pro(2)-Va1(3) as the corner residues. Theoretical and spectroscopic results are consistent with the presence of a transannular 4 - 1 hydrogen bond between Cys( 1) CO and Cys(4) NH groups, with the Val NH being sterically shielded from the solvent environment.

Thermochemical and kinetic studies on the effects of cobalt salicylate on the oxidative degradation of polystyrene

The effect of cobalt salicylate on the oxidative degradation and ignition of polystyrene has been studied. It was found that cobalt salicylate sensitizes both the degradation and ignition of polystyrene by facilitating electron-transfer processes in the propagation step. From thermochemical and kinetic studies it was found that the cobalt ion, owing to its ability to exist in variable valence states, promotes electron transfer in the propagation step of polymer degradation, increasing the rate of propagation and consequently the overall rate. Using solid-phase thermal ignition theory, an attempt has been made to explain the sensitization of ignition by the cobalt ion.