Visible Light Driven Ultrasensitive and Selective NO2 Detection in Tin Oxide Nanoparticles with Sulfur Doping Assisted by l-Cysteine.

In the pandemic era, the development of high-performance indoor air quality monitoring sensors has become more critical than ever. NO2 is one of the most toxic gases in daily life, which induces severe respiratory diseases. Thus, the real-time monitoring of low concentrations of NO2 is highly required. Herein, a visible light-driven ultrasensitive and selective chemoresistive NO2 sensor is presented based on sulfur-doped SnO2 nanoparticles. Sulfur-doped SnO2 nanoparticles are synthesized by incorporating l-cysteine as a sulfur doping agent, which also increases the surface area. The cationic and anionic doping of sulfur induces the formation of intermediate states in the band gap, highly contributing to the substantial enhancement of gas sensing performance under visible light illumination. Extraordinary gas sensing performances such as the gas response of 418 to 5 ppm of NO2 and a detection limit of 0.9 ppt are achieved under blue light illumination. Even under red light illumination, sulfur-doped SnO2 nanoparticles exhibit stable gas sensing. The endurance to humidity and long-term stability of the sensor are outstanding, which amplify the capability as an indoor air quality monitoring sensor. Overall, this study suggests an innovative strategy for developing the next generation of electronic noses.

Automated optimization of double heater convective polymerase chain reaction devices based on CFD simulation database and artificial neural network model.

This paper presents a framework for automated optimization of double-heater convective PCR (DH-cPCR) devices by developing a computational fluid dynamics (CFD) simulation database and artificial neural network (ANN) model. The optimization parameter space that includes the capillary tube geometries and the heater sizes of DH-cPCR is established, and a database consisting of nearly 10,000 CFD simulations is constructed. The database is then used to train a two-stage ANN models that select practically relevant data for modeling and predict PCR device performance. The trained ANN model is then combined with the gradient-based and the heuristics optimization approaches to search for optimal device configuration that possesses the shortest DNA doubling time. The entire design process including model meshing and configuration, parallel CFD computation, database organization, and ANN training and utilization is fully automated. Case studies confirm that the proposed framework can successfully find the optimal device configuration with an error of less than 0.3 s, and hence, representing a cost-effective and rapid solution of DH-cPCR device design.

Analysis of mouse male germ cell-specific or -predominant Tex13 family genes encoding proteins with transcriptional repressor activity.

Mammalian spermatogenesis is a highly organized process with successive mitotic, meiotic, and postmeiotic phases. This unique developmental process is characterized by the involvement of spermatogenic cell-specific genes. In this study, we identified and investigated testis expressed gene 13 (Tex13) family genes, consisting of Tex13a, Tex13b, Tex13c1, and Tex13d, in mice. All of these genes were transcribed specifically or predominantly in male germ cells, and their transcription was developmentally regulated. Proteins encoded by the Tex13 genes were predicted to have a conserved domain of ~ 145 amino acids. Tex13a, Tex13c1, and Tex13d encode additional C-terminal regions containing a short conserved sequence termed a zinc finger-RAN binding protein 2 (zf-RanBP2) or zf-RanBP2-like domain. As TEX13B reportedly has transcriptional repressor activity, we examined the effect of the TEX13 proteins on transcriptional regulation using a reporter assay. All of the TEX13 proteins exhibited transcriptional repressor activity. This activity was revealed to reside in the TEX13B-corresponding regions of TEX13A, TEX13C1, and TEX13D. Further, we found that the C-terminal regions of TEX13A, TEX13C1, and TEX13D also have inhibitory activities. These results suggest that male germ cell-specific or -predominant TEX13 proteins commonly function in transcriptional repression as transcription cofactors and/or RNA binding proteins.

Identification of a novel embryo-prevalent gene, Gm11545, involved in preimplantation embryogenesis in mice.

In mammals, the early embryo travels down the oviduct to the uterus and prepares for implantation. The unique features of preimplantation development include compaction followed by blastocyst formation. This first cell lineage specification involves various proteins including cell polarity regulators, kinases, and transcription factors. In this study, a novel gene named predicted gene 11545 (Gm11545) expressed predominantly in mouse early embryos was identified and characterized at the transcript, protein, cellular, and functional levels. The Gm11545 protein localized to both cytoplasmic and membrane regions of preimplantation embryos. Remarkably, knockdown of Gm11545 led to arrest of mouse embryos at the morula stage and consequent impairment of blastocyst formation. Expression patterns of the key transcription factors critical for early lineage specification, octamer-binding transcription factor 4 and caudal type homeobox 2, were affected by Gm11545 depletion. Based on the collective findings, we propose that the novel protein identified in this study, Gm11545, is implicated in cell proliferation and cell lineage specification critical for blastocyst formation.-Kim, J., Kim, J., Jeong, J., Hong, S. H., Kim, D., Choi, S., Choi, I., Oh, J. S., Cho, C. Identification of a novel embryo-prevalent gene, Gm11545, involved in preimplantation embryogenesis in mice.

SPATC1L maintains the integrity of the sperm head-tail junction.

Spermatogenesis is a tightly regulated process involving germ cell-specific and germ cell-predominant genes. Here we investigate a novel germ cell-specific gene, Spatc1l (spermatogenesis and centriole associated 1 like). Expression analyses show that SPATC1L is expressed in mouse and human testes. We find that mouse SPATC1L localizes to the neck region in testicular sperm. Moreover, SPATC1L associates with the regulatory subunit of protein kinase A (PKA). Using CRISPR/Cas9-mediated genome engineering, we generate mice lacking SPATC1L. Disruption of Spatc1l in mice leads to male sterility owing to separation of sperm heads from tails. The lack of SPATC1L is associated with a reduction in PKA activity in testicular sperm, and we identify capping protein muscle Z-line beta as a candidate target of phosphorylation by PKA in testis. Taken together, our results implicate the SPATC1L-PKA complex in maintaining the stability of the sperm head-tail junction, thereby revealing a new molecular basis for sperm head-tail integrity.

Mesoporous Si-Cu nanocomposite anode for a lithium ion battery produced by magnesiothermic reduction and electroless deposition.

Copper deposited mesoporous silicon was fabricated by magnesiothermic reduction and electroless deposition and its electrochemical properties as an anode for lithium ion batteries were investigated. The 300-400 nm sized mesoporous Si particles were synthesized by magnesiothermic reduction of SiO2 nanospheres prepared by the Stöber method. The mesopores of Si particles were effectively decorated with Cu using Sn sensitization/Pd activation and subsequent Cu electroless deposition. The homogeneous distribution of Cu inside the mesoporous Si particles was confirmed by high resolution transmission electron microscopy images and energy dispersive spectroscopy mapping on the cross-sectional specimen prepared by a focused ion beam. The mesoporous Si-Cu nanocomposite exhibited high initial Coulombic efficiency, long cycle stability, and high rate capability, delivering a high capacity of 1569 mAh g-1 after 200 cycles at the current density of 1000 mA g-1. The improved electrochemical performance in a mesoporous Si-Cu nanocomposite was attributed to the high electrical conductivity, high Li+ ion mobility, and structural stability to restrict the aggregation and pulverization of active materials.

Profiling of testis-specific long noncoding RNAs in mice.

BACKGROUND: Spermatogenesis, which is the complex and highly regulated process of producing haploid spermatozoa, involves testis-specific transcripts. Recent studies have discovered that long noncoding RNAs (lncRNAs) are novel regulatory molecules that play important roles in various biological processes. However, there has been no report on the comprehensive identification of testis-specific lncRNAs in mice. RESULTS: We performed microarray analysis of transcripts from mouse brain, heart, kidney, liver and testis. We found that testis harbored the highest proportion of tissue-specific lncRNAs (11%; 1607 of 14,256). Testis also harbored the largest number of tissue-specific mRNAs among the examined tissues, but the proportion was lower than that of lncRNAs (7%; 1090 of 16,587). We categorized the testis-specific lncRNAs and found that a large portion corresponded to long intergenic ncRNAs (lincRNAs). Genomic analysis identified 250 protein-coding genes located near (≤ 10 kb) 194 of the loci encoding testis-specific lincRNAs. Gene ontology (GO) analysis showed that these protein-coding genes were enriched for transcriptional regulation-related terms. Analysis of male germ cell-related cell lines (F9, GC-1 and GC-2) revealed that some of the testis-specific lncRNAs were expressed in each of these cell lines. Finally, we arbitrarily selected 26 testis-specific lncRNAs and performed in vitro expression analysis. Our results revealed that all of them were expressed exclusively in the testis, and 23 of the 26 showed germ cell-specific expression. CONCLUSION: This study provides a catalog of testis-specific lncRNAs and a basis for future investigation of the lncRNAs involved in spermatogenesis and testicular functions.

Effect of the Amine Concentration on Phase Evolution and Densification in Printed Films Using Cu(II) Complex Ink.

The nucleation and growth behavior of Cu nanoparticles during thermal heating of Cu(II) complex inks for printed Cu metallization were investigated, particularly focusing on the effects of the amine concentration on the microstructure evolution and electrical conductivity. Herein, the dual effects of hexylamine as a reducing agent dissociating the carboxyl group from the precursor and a capping agent hindering the subsequent growth of Cu nuclei were confirmed. On the basis of such dual effects of amine, the sufficient complexation of the Cu(II) precursor with a high amine concentration in the ink led to the single-route growth of Cu nanoparticles during thermal heating, which resulted in the dense film with a narrow particle size distribution exhibiting a high electrical conductivity. The electrical conductivity of the film could be further enhanced by a reducing atmosphere with formic acid. Significantly, the understanding of the ink chemistry and the nucleation and growth kinetics in the metal ion complex or metal-organic decomposition (MOD) ink can provide the design rules for the formulation of the solution-type inks to control the microstructure of printed metallization.

Direct printing synthesis of self-organized copper oxide hollow spheres on a substrate using copper(II) complex ink: gas sensing and photoelectrochemical properties.

The direct printing synthesis of metal oxide hollow spheres in the form of film on a substrate is reported for the first time. This method offers facile, scalable, high-throughput production and device fabrication processes. The printing was carried out via a doctor-blade method using Cu(II) complex ink with controllable high viscosity based on formate-amine coupling. Following only thermal heating in air, well-defined polycrystalline copper oxide hollow spheres with a submicrometer diameter (≤1 µm) were formed spontaneously while being assembled in the form of a film with good adhesion on the substrate. This spontaneous hollowing mechanism was found to result from the Kirkendall effect during oxidation at elevated temperature. The CuO films with hollow spheres, prepared via direct printing synthesis at 500 °C, led to the creation of a superior p-type gas sensor and photocathode for photoelectrochemical water splitting with completely hollow cores, a rough/porous shell structure, a single phase, high crystallinity, and no organic/polymer residue. As a result, the CuO hollow-sphere films showed high gas responses and permissible response speeds to reducing gases and high photocurrent density compared to conventional CuO powder films and the values previously reported. These results exemplify the successful realization of a high-throughput printing fabrication method for the creation of superior nanostructured devices.

Profiling of testis-specific or testis-predominant genes expressed in mouse male germ cell lines GC-1 and GC-2.

BACKGROUND: Spermatogenesis is a tightly organized process that utilizes an intrinsic genetic program composed of germ cell-specific genes. Although mouse germ cell-related cell lines are available, few germ cell-specific genes have been comprehensively identified in such cell lines. OBJECTIVE: We aimed to profile gene expression in the male mouse germ cell-related cell lines, GC-1 and GC-2, characterize their transcriptomic nature, and identify potential testis- or germ cell-specific or -predominant genes expressed in these cell lines. METHODS: We performed profiling analysis of genes transcribed in the mouse germ cell-related cell lines, GC-1 and GC-2, using our previous microarray data together with public transcriptome information. We analyzed the expression of a number of the cell line genes predicted to be preferentially expressed in testis by RT-PCR. RESULTS: We found that most testis-specific or -predominant mRNAs are not expressed in GC-1 and GC-2 cells, implying that these cell lines have lost their testis- or germ cell-specific genetic characteristics. RT-PCR analysis of genes predicted to be expressed in the cell lines with preferential testicular expression showed the testis-specific or -predominant expression of nine genes and verified four of them as being expressed in the germ cell lines. Among them, only cyclin-dependent kinase inhibitor 3 genes (Cdkn3) showed testis and germ cell specificity. CONCLUSION: Our study provides extensive transcriptomic information to shed light on the limited testicular characteristics of the mouse male germ cell-derived cell lines, GC-1 and GC-2, and offers a list of germ cell line genes with testicular preference.

Synthesis of Graphitic Carbon Coated ZnPS3 and its Superior Electrochemical Properties for Lithium and Sodium Ion Storage.

Graphitic carbon-coated ZnPS3 is prepared via direct phosphosulfurization and high energy mechanical milling (HEMM) with multiwall carbon nanotubes (MWCNTs) and first introduced as an anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The HEMM process with MWCNTs reduces the particle size of as-synthesized ZnPS3 bulk to 100-500 nm and yields the ≈5 nm thick graphitic carbon coated ZnPS3 nanoparticles, which are the nanocomposites of 5 nm sized nanocrystallites embedded in the amorphous matrix. The ZnPS3 electrode undergoes the combined conversion and alloying reactions with Li and Na ions and exhibits high initial discharge and charge capacities in both LIBs and SIBs. The graphitic carbon-coated ZnPS3 electrode exhibits excellent high-rate capability and long-term cyclability. The superior electrochemical properties can be attributed to high electrical conductivity, high Li ion mobility, and high reversibility and structural stability derived from the graphitic carbon-coated nanoparticles. This study demonstrates that the novel graphitic carbon-coated ZnPS3 is a promising anode material for both LIBs and SIBs and the graphitic carbon coating methodology by HEMM is expected to apply to the various metal oxides, sulfides, and phosphides.

Integrating metal-oxide-decorated CNT networks with a CMOS readout in a gas sensor.

We have implemented a tin-oxide-decorated carbon nanotube (CNT) network gas sensor system on a single die. We have also demonstrated the deposition of metallic tin on the CNT network, its subsequent oxidation in air, and the improvement of the lifetime of the sensors. The fabricated array of CNT sensors contains 128 sensor cells for added redundancy and increased accuracy. The read-out integrated circuit (ROIC) was combined with coarse and fine time-to-digital converters to extend its resolution in a power-efficient way. The ROIC is fabricated using a 0.35 µm CMOS process, and the whole sensor system consumes 30 mA at 5 V. The sensor system was successfully tested in the detection of ammonia gas at elevated temperatures.

Mapping the electrocatalytic water splitting activity of VO2 across its insulator-to-metal phase transition.

The electrocatalytic water splitting activity of V-based oxides has been rarely investigated, even though several polymorphs in VO2 are expected to exhibit different electrocatalytic activities depending on their crystal and electronic structures. The rutile structure of VO2(R), showing metallic character, is a good candidate for a new electrocatalyst since it undergoes insulator-to-metal transition (IMT) from the insulating VO2(M1) at a low temperature of 68 °C, and involves a substantially increased electrical conductivity by three orders of magnitude. The extensive improvements in the electrocatalytic activity for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) are confirmed when the IMT is induced where the overpotential (η10) is reduced from 1056 mV to 598 mV in the OER and 411 mV to 136 mV in the HER, respectively. This improvement is attributed to the increased electrochemically active surface area (ECSA), reduced charge transfer resistance, and increased electron density, driven by the IMT to the metallic VO2(R) phase.

Testicular germ cell-specific lncRNA, Teshl, is required for complete expression of Y chromosome genes and a normal offspring sex ratio.

Heat shock factor 2 (HSF2) regulates the transcription of the male-specific region of the mouse Y chromosome long arm (MSYq) multicopy genes only in testes, but the molecular mechanism underlying this tissue specificity remains largely unknown. Here, we report that the testicular germ cell-specific long noncoding RNA (lncRNA), NR_038002, displays a characteristic spatiotemporal expression pattern in the nuclei of round and elongating spermatids. NR_038002-knockout male mice produced sperm with abnormal head morphology and exhibited reduced fertility accompanied by a female-biased sex ratio in offspring. Molecular analyses revealed that NR_038002 interacts with HSF2 and thereby activates expression of the MSYq genes. We designate NR_038002 as testicular germ cell-specific HSF2-interacting lncRNA (Teshl). Together, our study is the first to demonstrate that the testis specificity of HSF2 activity is regulated by the lncRNA Teshl and establishes a Teshl-HSF2-MSYq molecular axis for normal Y-bearing sperm qualities and consequent balanced offspring sex ratio.

Transcriptome Analysis of Testicular Aging in Mice.

Male reproductive aging, or andropause, is associated with gradual age-related changes in testicular properties, sperm production, and erectile function. The testis, which is the primary male reproductive organ, produces sperm and androgens. To understand the transcriptional changes underlying male reproductive aging, we performed transcriptome analysis of aging testes in mice. A total of 31,386 mRNAs and 9387 long non-coding RNAs (lncRNAs) were identified in the mouse testes of diverse age groups (3, 6, 12, and 18 months old) by total RNA sequencing. Of them, 1571 mRNAs and 715 lncRNAs exhibited changes in their levels during testicular aging. Most of these aging-related transcripts exhibited slight and continuous expression changes during aging, whereas some (9.6%) showed larger expression changes. The aging-related transcripts could be classified into diverse expression patterns, in which the transcripts changed mainly at 3-6 months or at 12-18 months. Our subsequent in silico analysis provided insight into the potential features of testicular aging-related mRNAs and lncRNAs. We identified testis-specific aging-related transcripts (121 mRNAs and 25 lncRNAs) by comparison with a known testis-specific transcript profile, and then predicted the potential reproduction-related functions of the mRNAs. By selecting transcripts that are altered only between 3 and 18 months, we identified 46 mRNAs and 34 lncRNAs that are stringently related to the terminal stage of male reproductive aging. Some of these mRNAs were related to hormonal regulation. Finally, our in silico analysis of the 34 aging-related lncRNAs revealed that they co-localized with 19 testis-expressed protein-coding genes, 13 of which are considered to show testis-specific or -predominant expression. These nearby genes could be potential targets of cis-regulation by the aging-related lncRNAs. Collectively, our results identify a number of testicular aging-related mRNAs and lncRNAs in mice and provide a basis for the future investigation of these transcripts in the context of aging-associated testicular dysfunction.

SnO(2) nanotubes fabricated using electrospinning and atomic layer deposition and their gas sensing performance.

A novel method is developed to fabricate a SnO(2) nanotube network by utilizing electrospinning and atomic layer deposition (ALD), and the network sensor is proven to exhibit excellent sensitivity to ethanol owing to its hollow, nanostructured character. The electrospun polyacrylonitrile (PAN) nanofibers of 100-200 nm diameter are used as a template after stabilization at 250 degrees C. An uniform and conformal SnO(2) coating on the nanofiber template is achieved by ALD using dibutyltindiacetate (DBTDA) as the Sn source at 100 degrees C and the wall thickness is precisely controlled by adjusting the number of ALD cycles. The calcination at 700 degrees C transforms the amorphous nanofibers into SnO(2) nanotubes composed of several nanometer-sized crystallites. The SnO(2) nanotube network sensor responds to ethanol, H(2), CO, NH(3) and NO(2) gases, but it exhibited an extremely high gas response to ethanol with a short response time (<5 s). The results demonstrate that the combination of electrospinning and ALD is a very effective and promising technique to fabricate long and uniform metal oxide nanotubes with the precise control of wall thickness, which can be applied to various applications such as gas sensors and lithium ion batteries.

H(2) sensing characteristics of SnO(2) coated single wall carbon nanotube network sensors.

SnO(2) nanoparticle coated single wall nanotube (SWNT) network sensors were fabricated by forming a SWNT network on the Pt patterned SiO(2)/Si substrate using a dip coating method and subsequently depositing SnO(2) nanoparticles on the SWNT network by rf magnetron sputtering. Their H(2) gas sensing properties were investigated. The SnO(2)-SWNT network sensors stably and reversibly responded to H(2) gas even at room temperature and could detect H(2) gas down to 100 ppm. In addition to the low temperature detection, a remarkable finding was that the gas sensing behavior of SnO(2)-SWNT network sensors was changed from p-type to n-type with increasing SnO(2) deposition time (i.e. surface coverage of SnO(2) on SWNT). A schematic model was proposed to explain the switching of sensing behavior depending on the surface coverage of SnO(2) nanoparticles on the SWNTs.

Normal fertility in male mice lacking ADAM32 with testis-specific expression.

The a disintegrin and metalloprotease (ADAM) family proteins comprise a group of membrane-anchored proteins. ADAM32 is expressed specifically in testis and is closely related phylogenetically to ADAM2 and ADAM3, which are known to be critical for fertilization in mice. To assess the biological role of ADAM32, we analyzed Adam32-mutant mice. We found that male mice lacking ADAM32 have normal fertility, testicular integrity, and sperm characteristics. ADAM32 was found to exist at lower levels than ADAM2 and ADAM3 in wild-type testis and sperm, respectively. The present study demonstrates that ADAM32 is dispensable for fertility and appears to be functionally unrelated to ADAM2 and ADAM3 in mice.

Surrogate-based optimization with adaptive sampling for microfluidic concentration gradient generator design.

This paper presents a surrogate-based optimization (SBO) method with adaptive sampling for designing microfluidic concentration gradient generators (µCGGs) to meet prescribed concentration gradients (CGs). An efficient physics-based component model (PBCM) is used to generate data for Kriging-based surrogate model construction. In a comparative analysis, various combinations of regression and correlation models in Kriging, and different adaptive sampling (infill) techniques are inspected to enhance model accuracy and optimization efficiency. The results show that the first-order polynomial regression and the Gaussian correlation models together form the most accurate model, and the lower bound (LB) infill strategy in general allows the most efficient global optimum search. The CGs generated by optimum designs match very well with prescribed CGs, and the discrepancy is less than 12% even with an inherent limitation of the µCGG. It is also found that SBO with adaptive sampling enables much more efficient and accurate design than random sampling-based surrogate modeling and optimization, and is more robust than the gradient-based optimization for searching the global optimum.

A MnV2O6/graphene nanocomposite as an efficient electrocatalyst for the oxygen evolution reaction.

A MnV2O6/graphene nanocomposite was fabricated through hydrothermal synthesis and high energy milling to introduce it as an efficient OER electrocatalyst. The MnV2O6/graphene nanocomposite with 20 wt% graphene exhibited superior electrocatalytic OER performance with a low overpotential and high stability and durability in 1 M KOH aqueous solution, exhibiting even after 1000 CV cycles.