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The creep rupture properties of Sn–3.5Ag based ternary alloys with varying amounts of Cu or Bi were investigated using rolled and heat-treated bulk specimens. Nominal compositions of the third element were 0% (Base), 0.5, 0.75, 1.0 and 1.5% Cu and 2.5, 4.8, 7.5 and 10% wt% Bi, respectively. The alloys generally showed the secondary and tertiary creep characteristics only, and the minimum strain rates e min were lowest for the 0.75 Cu specimens, and highest for the 10 Bi specimens. The stress exponents (n) of e min were usually around 4 ± 1, with the exception of the 0.5 Cu and 0.75 Cu alloys with n=6.0∼7.6, and the 10 Bi alloy which showed n ~ 2. Fractographic analyses revealed typical creep rupture by the nucleation and growth of cavities in the matrix for the Base and Cu-containing alloy except the 1.5 Cu specimens, which showed cavity nucleation by the cracking of brittle Cu6Sn5 particles. On the other hand, all the Bi-containing alloys showed cavity nucleation on grain boundaries due to the segregation of Bi to the β-Sn grain boundaries. Subsequent rupture time analyses showed that creep rupture by necking could predict rupture times of the Base and the Cu-containing alloys reasonably, and that the model based on the continual nucleation of cavitating facets could explain the rupture times of the Bi-containing alloys reasonably well. The Kachanov equation made reasonable predictions of the rupture time for all cases.

With the earth's abundance of kesterite, recent progress in chalcogenide based Cu2ZnSn(Sx,Se1−x)4 (CZTSSe) thin films has drawn prime attention in thin film solar cells (TFSCs) research and development. This review is focused on the current developments in the synthesis of CZTS nanocrystals (NCs) using a hot injection (HI) technique and provides comprehensive discussions on the current status of CZTSSe TFSCs. This article begins with a description of the advantages of nanoparticulate based thin films, and then introduces the basics of this technique and the corresponding growth mechanism is also discussed. A brief overview further addresses a series of investigations on the developments in the HI based CZTSSe NCs using different solvents in terms of their high toxicity to environmentally benign materials. A variety of recipes and techniques for the NCs ink formulation and thereby the preparation of absorber layers using NC inks are outlined, respectively. The deposition of precursor thin films, post-deposition processes such as sulfurization or selenization treatments and the fabrication of CZTSSe NCs based solar cells and their performances are discussed. Finally, we discussed concluding remarks and the perspectives for further developments in the existing research on CZTSSe based nanoparticulate (NP) TFSCs towards future green technology.

With the earth's abundance of kesterite, recent progress in chalcogenide based Cu2ZnSn(Sx,Se1−x)4 (CZTSSe) thin films has drawn prime attention in thin film solar cells (TFSCs) research and development. This review is focused on the current developments in the synthesis of CZTS nanocrystals (NCs) using a hot injection (HI) technique and provides comprehensive discussions on the current status of CZTSSe TFSCs. This article begins with a description of the advantages of nanoparticulate based thin films, and then introduces the basics of this technique and the corresponding growth mechanism is also discussed. A brief overview further addresses a series of investigations on the developments in the HI based CZTSSe NCs using different solvents in terms of their high toxicity to environmentally benign materials. A variety of recipes and techniques for the NCs ink formulation and thereby the preparation of absorber layers using NC inks are outlined, respectively. The deposition of precursor thin films, post-deposition processes such as sulfurization or selenization treatments and the fabrication of CZTSSe NCs based solar cells and their performances are discussed. Finally, we discussed concluding remarks and the perspectives for further developments in the existing research on CZTSSe based nanoparticulate (NP) TFSCs towards future green technology.

After fertilization, the sperm and oocyte genomes undergo extensive epigenetic reprogramming to form a totipotent zygote. The dynamic epigenetic changes during early embryo development primarily involve DNA methylation and demethylation. We have previously identified Gse (gonad-specific expression gene) to be expressed specifically in germ cells and early embryos. Its encoded protein GSE is predominantly localized in the nuclei of cells from the zygote to blastocyst stages, suggesting possible roles in the epigenetic changes occurring during early embryo development. Here, we report the involvement of GSE in epigenetic reprogramming of the paternal genome during mouse zygote development. Preferential binding of GSE to the paternal chromatin was observed from pronuclear stage 2 (PN2) onward. A knockdown of GSE by antisense RNA in oocytes produced no apparent effect on the first and second cell cycles in preimplantation embryos, but caused a significant reduction in the loss of 5-methylcytosine (5mC) and the accumulation of 5-hydroxymethylcytosine (5hmC) in the paternal pronucleus. Furthermore, DNA methylation levels in CpG sites of LINE1 transposable elements, Lemd1, Nanog and the upstream regulatory region of the Oct4 (also known as Pou5f1) gene were clearly increased in GSE-knockdown zygotes at mid-pronuclear stages (PN3-4), but the imprinted H19-differential methylated region was not affected. Importantly, DNA immunoprecipitation of 5mC and 5hmC also indicates that knockdown of GSE in zygotes resulted in a significant reduction of the conversion of 5mC to 5hmC on LINE1. Therefore, our results suggest an important role of maternal GSE for mediating active DNA demethylation in the zygote.

Cu(2)ZnSnS(4) (CZTS) thin films were prepared by the sequential sulfurization of a co-sputtered precursor with a multitarget (Cu, ZnS, and SnS(2)) sputtering system. In order to investigate the crystallization behaviour of the thin films, the precursors were sulfurized in a tube furnace at different temperatures for different time durations. The Raman spectra of the sulfurized thin films showed that their crystallinity gradually improved with an increase in the sulfurization temperature and duration. However, transmission electron microscopy revealed an unexpected result-the precursor thin films were not completely transformed to the CZTS phase and showed the presence of uncrystallized material when sulfurized at 250-400 °C for 60 min and at 500 °C for 30 min. Thus, the crystallization of the co-sputtered precursor thin films showed a strong dependence on the sulfurization temperature and duration. The crystallization mechanism of the precursor thin films was understood on the basis of these results and has been described in this paper. The understanding of this mechanism may improve the standard preparation method for high-quality CZTS absorber layers.

In mammalian oocytes, the ubiquitin-proteasome system (UPS) is suggested to play important roles in oocyte meiosis resumption, spindle assembly, polar body emission and pronuclear formation by regulating cyclin B1 degradation. However, little is known about the direct relationship between zygotic gene activation (ZGA) and degradation of maternal proteins. Here, we investigated the role of the UPS in the onset of ZGA in early mouse embryos. First, we found degradation of cyclin B1 protein in fertilized oocytes at 1 hpi by western blot analysis and used these oocytes throughout this study. Subsequently, we determined optimal experimental conditions for transient inhibition of proteasomal activity by specific and reversible proteasomal inhibitor MG132 in the G1 phase of the first cell cycle. Under the selected optimal conditions, we subjected transient MG132-treated embryos to reverse transcription (RT)-PCR analysis of expression of four ZGA genes, i.e., the hsp70.1, MuERV-L, eif-1a and zscan4d genes. As a result, we found that onset of expression of the four examined ZGA genes was delayed in both normally developed 2-cell embryos and arrested 1-cell embryos. Our results indicate that proteasomal degradation of proteins by the UPS plays a pivotal role in the molecular mechanisms of ZGA in early mouse embryos.

The nanocrystalline Zinc Sulfide (ZnS) thin films were prepared on glass substrates by chemical bath deposition (CBD) method using aqueous solutions of zinc acetate, thiourea and tri-sodium citrate in alkaline medium at 80 degrees C. The tri-sodium citrate acts as a complexing agent. The effects of complexing agent and annealing atmosphere (95%N2 + 5%H2S) on structural, morphological and optical properties of ZnS thin films were studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and optical absorption. XRD study revealed that single phase ZnS powder was formed in the solution with tri-sodium citrate, however, ZnS and ZnO mixed phase powder was formed in the solution without tri-sodium citrate. The films deposited with trisodium citrate showed ZnS with hexagonal wurtzite phase. However, annealed film in (N2 + H2S) atmosphere showed cubic (zincblende) phase. FE-SEM images show that grain size of as-deposited and annealed ZnS films are about 20 nm and 50 nm, respectively. Optical absorption study showed that the films have moderate optical transmission from 65% to 75% in the visible region and the optical band gap energy of as-deposited ZnS film is 3.91 eV and it decreases to 3.73 eV after annealing.

Functional and structural changes in the mammalian ovary are coordinately regulated by the pituitary glycoprotein hormones, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), leading to follicular development, ovulation and transformation of follicles into corpus lutea. To investigate protein profiles during these processes of the mouse ovarian cycle, we applied combined methods (two-dimensional gel electrophoresis [2-DE] for separation and visualization of proteins plus matrix laser desorption/ionization time-of-flight mass spectrometry [MALDI-TOF/MS] analysis for protein identification) for comparative proteomic analysis using immature mice at 3 weeks of age. Protein profiles were obtained from proteins extracted from intact ovaries that had been collected from pregnant mare serum gonadotropin (PMSG)/human chorionic gonadotropin (hCG)-primed immature mice at 0 (no PMSG), 24 and 48 h post PMSG, as well as at 10 and 20 h post hCG. The results showed that 1028 common protein spots were found in representative gels that had been separated in the 3 to 11 pH range and the 15-200 kDa range, 253 protein spots (24.6%) of which were differentially expressed (p

In the recent semiconductor mass production, the tri-layer hardmask system has become crucial for successful patterning in many applications. Silicon-based anti-reflective spin-on hardmask (Si-SOH), which can be built by spin-on coating, is desirable in terms of mass production throughput and the overall cost of ownership. As the pattern size shrinks, the thickness of photoresist also becomes thinner, which forces the thickness of Si-SOH to be thinner resulting in a tighter thickness margin. In this case, controlling optical properties of Si-SOH becomes important in order to achieve low reflectivity in the exposure process. In addition, the tri-layer system can be set up more easily when the etch properties of Si-SOH can be controlled. Previously, we reported papers on silicon-based anti-reflective spin-on hardmask materials for 193 nm lithography, immersion ArF lithography, and optimization of optical properties of Si-SOH. In this paper, the technique for controlling etch properties of Si-SOH by a different type of monomer is described. To control etch properties in the same resin platform, the synthesis method was modified. Characterization of the Si-SOH synthesized by the new technique and the lithographic performance using this material are described in detail.

In the current semiconductor industry, hardmasks have become essential for successful patterning in many applications. Silicon-based anti-reflective spin-on hardmask (Si-SOH), which can be built by spin-on coating, is desirable in terms of mass production throughput and cost of ownership. As the design rule shrinks, the thickness of photoresist also becomes thinner, which forces the thickness of Si-SOH to be thinner resulting in a tighter thickness margin. In this case, controlling of optical properties of Si-SOH is important in order to obtain low reflectivity in the exposure process. Previously, we reported papers on silicon-based anti-reflective spin-on hardmask materials for 193 nm lithography and immersion ArF lithography. In this paper, the technique for optimization of optical properties, especially n and k values, of Si-SOH is described. To control n and k values, several chromophores were screened and the ratio among them was optimized. Although the amount of chromophores increased and the silicon contents decreased, our etch resistance enhancement technique allowed Si-SOH to have sufficient etch resistance. Characterization of this Si-SOH and lithographic performance using these materials are described in detail.

We isolated a mouse cDNA, zag1 (zygotic gene activation-associated gene 1), that has an open reading frame of 1,728-bp encoding a protein of 66.2 kDa including both a bipartite nuclear targeting sequence and a P-loop motif containing nucleoside triphosphate hydrolase motifs. Northern blot analysis of mouse tissues showed that zag1 was widely expressed but was especially prominent in the ovary and testis. RT-PCR analysis of in vitro fertilized embryos showed that the abundance of zag1 transcripts in oocytes decreased after fertilization, and zag1 mRNA was detected at 15 h post insemination (hpi) in fertilized embryos indicating that the gene was expressed at the start of zygotic gene activation at the mouse 1-cell stage. The nuclear-localization of ZAG1 protein in mouse preimplantation embryos at 15 hpi was confirmed by both subcellular analysis of enhanced green fluorescent protein (EGFP)-tagged ZAG1 and immunocytochemical analysis with anti-ZAG1 antibody. Subsequently, using yeast two-hybrid screening, we identified U2 small nuclear ribonucleoprotein B (U2B"), which is associated with pre-mRNA splicing, as a putative interacting partner of ZAG1 protein. Furthermore, knockdown of zag1 expression by an antisense DNA plasmid induced arrest and/or delay of embryonic development in injected 1-cell embryos. These results suggest that ZAG1 may be closely associated with zygotic gene expression in mouse preimplantation embryos.

A novel approach of successive ionic adsorption and reaction (SILAR) with a modified sequence is developed to synthesize Cu2ZnSnS4 (CZTS) films with outstanding photovoltaic characteristics. The influence of different anionic bath immersion times on the properties of CZTS films is investigated. The best PEC of 2.33% with a maximum Jsc of 12.88 mA cm−2, Voc of 0.42 V and FF of 0.43 is obtained for the lower value of anionic bath immersion time.

(CZTSSe) thin films were prepared by sulfurization of evaporated precursor thin films. Precursor was prepared using evaporation method at room temperature. The sulfurization was carried out in a graphite box with S powder at different temperatures. The temperatures were varied in a four step process from to . The effects of the sulfurization temperature on the micro-structural, morphological, and compositional properties of the CZTSSe thin films were investigated using X-ray diffraction (XRD), Raman spectra, field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The XRD and Raman results showed that the sulfurized thin films had a single kesterite crystal CZTSSe. From the FE-SEM and TEM results, the (MoSSe) interfacial layers of the sulfurized CZTS thin films were observed and their thickness was seen to increase with increasing sulfurization temperature. The microstructures of the CZTSSe thin films were strongly related to the sulfurization temperatures. The voids in the CZTSSe thin films increased with the increasing sulfurization temperature.

Al doped ZnO (AZO) thin films were prepared on ZnO coated glass substrates by hydrothermal synthesis technique using aqueous solutions containing zinc nitrate hexahydrate, ammonium hydroxide, and different sodium citrate concentrations at 60 °C for 6 h. The effects of different trisodium citrate concentrations on the microstructural, crystallinity, morphological, optical, and chemical properties of thin films were investigated. X-ray diffraction studies showed that the AZO thin films were grown as a polycrystalline wurtzite hexagonal phase with a c-axis preferred orientation and without an unwanted second phase regardless of trisodium citrate concentrations. The thickness and grain sizes of AZO thin films decreased with increasing trisodium citrate concentration. The microstructure of AZO thin films was changed from flat to needle shaped and the morphology was smoother with increasing trisodium citrate concentrations. The AZO thin films have a high transmittance in the visible region ranging from 75 to 85% and a sharp edge from 366 to 374 nm.

Cu2ZnSnS4 (CZTS) thin films were prepared by the sequential sulfurization of a co-sputtered precursor with a multitarget (Cu, ZnS, and SnS2) sputtering system. In order to investigate the crystallization behaviour of the thin films, the precursors were sulfurized in a tube furnace at different temperatures for different time durations. The Raman spectra of the sulfurized thin films showed that their crystallinity gradually improved with an increase in the sulfurization temperature and duration. However, transmission electron microscopy revealed an unexpected result—the precursor thin films were not completely transformed to the CZTS phase and showed the presence of uncrystallized material when sulfurized at 250–400 °C for 60 min and at 500 °C for 30 min. Thus, the crystallization of the co-sputtered precursor thin films showed a strong dependence on the sulfurization temperature and duration. The crystallization mechanism of the precursor thin films was understood on the basis of these results and has been described in this paper. The understanding of this mechanism may improve the standard preparation method for high-quality CZTS absorber layers.

Chalcogenide-based semiconductors, such as CuInSe2, CuGaSe2, Cu(In,Ga)Se2 (CIGS), and CdTe have attracted considerable interest as efficient materials in thin film solar cells (TFSCs). Currently, CIGS and CdTe TFSCs have demonstrated the highest power conversion efficiency (PCE) of over 11% in module production. However, commercialized CIGS and CdTe TFSCs have some limitations due to the scarcity of In, Ga, and Te and the environmental issues associated with Cd and Se. Recently, kesterite CZTS, which is one of the In- and Ga- free absorber materials, has been attracted considerable attention as a new candidate for use as an absorber material in thin film solar cells. The CZTS-based absorber material has outstanding characteristics such as band gap energy of 1.0 eV to 1.5 eV, high absorption coefficient on the order of 104cm-1, and high theoretical conversion efficiency of 32.2% in thin film solar cells. Despite these promising characteristics, research into CZTS-based thin film solar cells is still incomprehensive and related reports are quite few compared to those for CIGS thin film solar cells, which show high efficiency of over 20%. The recent development of kesterite-based CZTS thin film solar cells is summarized in this work. The new challenges for enhanced performance in CZTS thin films are examined and prospective issues are addressed as well.

In this paper, we report a facile, low cost synthesis and characterization of kesterite Cu2ZnSn(Sx,Se1−x)4 (CZTSSe) nanocrystals (NCs) by a two-step process involving a solution-based precursor and a post-annealing route. The effects of different Se vaporization temperatures, ranging from 350 °C to 550 °C, on the structural, chemical, compositional, and optical properties of CZTSSe NCs were investigated. X-ray diffraction patterns, Raman spectroscopy, and transmission electron microscopy results indicated that the precursor powder showed several broad peaks that could not be assigned to Cu2ZnSnS4 (CZTS), ZnS, Cu2−xS, Sn2S3 and Cu2SnS3. However, the post-annealed NCs with and without Se vaporization were a single kesterite CZTS phase without a secondary phase. UV-vis spectroscopy results showed that the absorption coefficients of all the post-annealed NCs were over 104 cm−1 in the visible region, and the optical band gap energy decreased systematically from 1.46 eV to 1.14 eV with increasing Se vaporization temperatures.

It has been reported that activity of Rho, one of the GTPases, is essential for division of nuclei and cytoplasm of fertilized mouse eggs. Since it has been reported that alteration of activities of GTPases modifies their ability to attach to each of their effector proteins in somatic cells, effector proteins seem to be able to control not only progression but also repression of cell division by changing their cellular localizations through activities of GTPases. For this reason, Rhophilin-2, one of the effector proteins of Rho, seems to be involved in the decision of progression of division of fertilized mouse eggs. To examine whether this involvement works in fertilized mouse eggs, cellular localization of Rho and Rhophilin-2 in fertilized mouse eggs that were treated with Rho inhibitor were analyzed. Moreover, cellular localization of GABA A receptor association protein (GABARAP), which was identified in our previous study (Matsuoka et al. 2006 Reprod. Fertil. Dev. 18, 176–177) as a protein that interacts with Rhophilin-2, was also analyzed. Fertilized mouse eggs were obtained from in vitro fertilization technique. One group of fertilized eggs was obtained at 24 h after insemination as experimental control. To obtain the mouse eggs in which Rho activities were inhibited, Clostridium botulinum C3 exoenzyme (C3-CB), an inhibitor of Rho activity, was injected into the other group of fertilized mouse eggs at 12 h after insemination, and were collected after 12 h of subsequent culture. Cellular localization of Rho (n = 100), Rhophilin-2 (n = 10). and GABARAP (n = 10) in the collected oocytes was analyzed by using immunofluorescence. Our results showed that Rho and Rhophilin-2 were co-localized at the midbody microtubule, which is an important device for cytoplasmic division in control eggs. However, the inhibition of Rho activity did not modify the co-localization of Rho and Rhophilin-2. On the other hand, localization of GABARAP was modified by the inhibition of Rho activity, and GABARAP was detected around the nuclei of fertilized eggs in which Rho activity was inhibited. In the next experiment, we examined whether interaction of Rhophilin-2 and GABARAP was modified by the inhibition of Rho activity by using a co-immunoprecipitation assay (co-IP) (n = 100). The interaction of Rhophilin-2 and GABARAP was found to disappear after inhibition of Rho activity. These results suggest that activity of Rho seems to regulate cytoplasmic division through Rhophilin-2 modification. Moreover, Rho seem to modulate the nuclear division of fertilized mouse eggs by regulating the interaction between Rhophilin-2 and GABARAP. This study was supported by a Grant-in-Aid for the 21st Century COE Program of the Japan Mext and by a grant for the Wakayama Prefecture Collaboration of Regional Entities for the Advancement of Technology Excellence of the JST.

Zygotic gene activation (ZGA) starts at the G2 phase at the 1-cell stage in the mouse. However, the molecular mechanism of ZGA has not been completely elucidated. We have investigated the molecular functions of many gene clusters, DD clones obtained by differential display assays for ovulated eggs at the M II stage and 1-cell stage embryos at the G2 phase. As a result, we have identified a functionally unknown gene, whose sequence did not match a known transcript in the gene bank DD2-2 gene. Here, we report the expression profile and knockdown analysis of the DD2-2 gene in mouse pre-implantation embryos. Nucleotide sequence analysis of the DD2-2 cDNA revealed that the open reading frame of 1056 bp encodes a protein of 351 amino acids with a predicted molecular mass of 41.5 kDa. The deduced amino acid sequence indicated that DD2-2 protein might be a soluble protein without a signal peptide. We first investigated the expression profiles of DD2-2 in pre-implantation embryos by quantitative real-time PCR using an ABI PRISM 7300 Sequence Detection System (Applied Biosystems, Foster City, CA, USA). To investigate the effect of knockdown of the DD2-2 gene on the development of pre-implantation embryos, we injected pβ-act/antisenseDD2-2/IRES/EGFP into male pronuclei of embryos at 7 to 9 h after insemination (hpi) and observed the development of embryos that showed EGFP expression at 24 hpi. Real-time PCR analysis of pre-implantation embryos showed that maternal DD2-2 mRNA at a low level significantly increased up to the early 2-cell stage, and significantly decreased by the 4-cell stage and later, suggesting that DD2-2 gene specifically expresses at major ZGA. In the knockdown analysis, EGFP-positive embryos with pβ-act/antisenseDD2-2/IRES/EGFP showed a lower rate of development to the 4-cell stage and later, compared with that of EGFP-positive embryos with pβ-act/luc+/IRES/EGFP [72% (94/130) vs. 54% (71/131); P < 0.05], indicating that the knockdown of DD2-2 by antisense RNA resulted in a inhibition of pre-implantation development. In conclusion, the DD2-2 gene, a functionally unknown gene, may play an important role in pre-implantation development. This study was supported by a Grant-in-Aid for the 21st Century COE Program of the Japan Mext and by a grant for the Wakayama Prefecture Collaboration of Regional Entities for the Advancement of Technology Excellence of the JST.

Structural, electrical resistivity, and magnetization properties of 200-MeV Ag+15-ion-irradiated Co-implanted ZnO thin films are presented. The structural studies show the presence of Co clusters whose size is found to increase with increase of Co implantation. The implanted films were irradiated with 200-MeV Ag+15 ions to fluence of 1×1012ions∕cm2. The Co clusters on irradiation dissolve in the ZnO matrix. The electrical resistivity of the irradiated samples is lowered to half. The magnetization hysteresis measurements show ferromagnetic behavior at 300K, and the coercive field increases with the Co implantation. The ferromagnetism at room temperature is confirmed by magnetic force microscopy measurements. The results are explained on the basis of the close interplay between the electrical and the magnetic properties.

Transparent conductive and flexible Mg and Ga co-doped ZnO (MGZO) thin films were prepared on poly-ethylene terephthalate (PET) by RF magnetron sputtering technique at room temperature. The effects of different working pressures on the structural, chemical, morphological, optical and electrical properties of MGZO thin films were investigated. X-ray diffraction results indicate that all the MGZO thin films were grown as polycrystalline wurtzite structures without secondary phases such as MgO, Ga2O3, MgGa2O4, or ZnGa2O4. The MGZO thin film prepared at 6mTorr has the lowest value of full width at half maximum. A typical survey spectrum of all the MGZO thin films confirmed the presence of Mg, Ga, Zn and O. The MGZO thin film prepared at 6mTorr showed the widest optical band gap energy of 3.91eV and lowest electrical resistivity of 5.3×10−3Ωcm.