Measurement of dielectric function and bandgap of germanium telluride using monochromated electron energy-loss spectroscopy

Using a monochromator in transmission electron microscopy, a low-energy-loss spectrum can provide inter- and intra-band transition information for nanoscale devices with high energy and spatial resolutions. However, some losses, such as Cherenkov radiation, phonon scattering, and surface plasmon resonance superimposed at zero-loss peak, make it asymmetric. These pose limitations to the direct interpretation of optical properties, such as complex dielectric function and bandgap onset in the raw electron energy-loss spectra. This study demonstrates measuring the dielectric function of germanium telluride using an off-axis electron energy-loss spectroscopy method. The interband transition from the measured complex dielectric function agrees with the calculated band structure of germanium telluride. In addition, we compare the zero-loss subtraction models and propose a reliable routine for bandgap measurement from raw valence electron energy-loss spectra. Using the proposed method, the direct bandgap of germanium telluride thin film was measured from the low-energy-loss spectrum in transmission electron microscopy. The result is in good agreement with the bandgap energy measured using an optical method.

Colossal Dielectric Perovskites of Calcium Copper Titanate (CaCu3 Ti4 O12 ) with Low-Iridium Dopants Enables Ultrahigh Mass Activity for the Acidic Oxygen Evolution Reaction

Oxygen evolution reaction (OER) under acidic conditions becomes of significant importance for the practical use of a proton exchange membrane (PEM) water electrolyzer. In particular, maximizing the mass activity of iridium (Ir) is one of the maiden issues. Herein, the authors discover that the Ir-doped calcium copper titanate (CaCu₃Ti₄O₁₂, CCTO) perovskite exhibits ultrahigh mass activity up to 1000 A g_Ir ^-1 for the acidic OER, which is 66 times higher than that of the benchmark catalyst, IrO₂ . By substituting Ti with Ir in CCTO, metal-oxygen (M-O) covalency can be significantly increased leading to the reduced energy barrier for charge transfer. Further, highly polarizable CCTO perovskite referred to as "colossal dielectric", possesses low defect formation energy for oxygen vacancy inducing a high number of oxygen vacancies in Ir-doped CCTO (Ir-CCTO). Electron transfer occurs from the oxygen vacancies and Ti to the substituted Ir consequentially resulting in the electron-rich Ir and -deficient Ti sites. Thus, favorable adsorptions of oxygen intermediates can take place at Ti sites while the Ir ensures efficient charge supplies during OER, taking a top position of the volcano plot. Simultaneously, the introduced Ir dopants form nanoclusters at the surface of Ir-CCTO, which can boost catalytic activity for the acidic OER.

In Situ Observation of the Early Stages of Rapid Solid-Liquid Reaction in Closed Liquid Cell TEM Using Graphene Encapsulation

In situ liquid cell transmission electron microscopy (TEM) is a very useful tool for investigating dynamic solid–liquid reactions. However, there are challenges to observe the early stages of spontaneous solid–liquid reactions using a closed-type liquid cell system, the most popular and simple liquid cell system. We propose a graphene encapsulation method to overcome this limitation of closed-type liquid cell TEM. The solid and liquid are separated using graphene to suspend the reaction until the graphene layer is destroyed. Graphene can be decomposed by the high-energy electron beam used in TEM, allowing the reaction to proceed. Fast dissolution of graphene-capped copper nanoparticles in an FeCl3 solution was demonstrated via in situ liquid cell TEM at 300 kV using a cell with closed-type SiNx windows.

Green ammonia synthesis using CeO2/RuO2 nanolayers on vertical graphene catalyst via electrochemical route in alkaline electrolyte

The electrochemical synthesis of ammonia at ambient temperature and pressure has the potential to replace the conventional process for the production of ammonia. However, the low ammonia yield and poor long-term stability of catalysts for the synthesis of ammonia hinders the application of this technology. Herein, we endeavored to tackle this challenge by synthesizing 3-D vertical graphene (VG) on Ni foam via a one-step, low-temperature plasma process, which offered high conductivity and large surface area. Subsequently, the vertical graphene on Ni foam was loaded with nanolayers of ruthenium oxide (RuO₂, ∼2 nm) and cerium oxide (CeO₂, <20 nm) nanoparticles via magnetron sputtering. The incorporation of nanoparticle layers (RuO₂ and CeO₂/RuO₂) on VG significantly increased the NH₃ yield in KOH electrolyte. Finally, the performance and long-term stability of this composite material were successfully demonstrated by the addition of CeO₂/RuO₂ nanolayers on the VG electrocatalyst. The catalyst achieved an excellent performance with a high ammonia synthesis yield of 50.56 μg mg_{total cat.}^-1 h^-1 (1.11 × 10^-10 mol cm^-2 s^-1) during the performance evaluation period of 36 h. This observation was also verified by density functional theory calculation, where CeO₂ exhibited the best catalytic performance compared to RuO₂ and pristine graphene.

Comparison between Fe2O3/C and Fe3C/Fe2O3/Fe/C Electrocatalysts for N2 Reduction in an Alkaline Electrolyte

Cost-effective and nonprecious iron-based catalysts were synthesized, evaluated, and compared for electrocatalytic N₂ reduction reaction (NRR) under alkaline conditions in the potential range from -0.4 to 0.1 V [vs reversible hydrogen electrode (RHE)] at low temperature (≤60 °C) and atmospheric pressure. The tested H-type cell was separated by an anion exchange membrane in 6 M KOH alkaline electrolyte (pH = over 14) in order to minimize hydrogen evolution reaction and to directly form NH₃ gas. The amount of ammonia synthesized was quantified using an indophenol blue method and cross-checked with ¹H nuclear magnetic resonance spectroscopy and ion chromatography using both ¹⁴N₂ and ¹⁵N₂ gases. Because of the synergistic effect between the Fe₃C, Fe₂O₃, and Fe composites in the NRR, both the ammonia formation rate and faradaic efficiency in Fe₃C/Fe₂O₃/Fe/C were approximately fourfold higher than those in Fe₂O₃/C at 60 °C and 0.1 V (vs RHE). These results can provide insights into designing Fe-based electrocatalysts for NRR at atmospheric pressure.

Realization of Wafer-Scale 1T-MoS2 Film for Efficient Hydrogen Evolution Reaction

The octahedral structure of 2D molybdenum disulfide (1T-MoS₂ ) has attracted attention as a high-efficiency and low-cost electrocatalyst for hydrogen production. However, the large-scale synthesis of 1T-MoS₂ films has not been realized because of higher formation energy compared to that of the trigonal prismatic phase (2H)-MoS₂ . In this study, a uniform wafer-scale synthesis of the metastable 1T-MoS₂ film is performed by sulfidation of the Mo metal layer using a plasma-enhanced chemical vapor deposition (PE-CVD) system. Thus, plasma-containing highly reactive ions and radicals of the sulfurization precursor enable the synthesis of 1T-MoS₂ at 150 °C. Electrochemical analysis of 1T-MoS₂ shows enhanced catalytic activity for the hydrogen evolution reaction (HER) compared to that of previously reported MoS₂ electrocatalysts 1T-MoS₂ does not transform into stable 2H-MoS₂ even after 1000 cycles of HER. The proposed low-temperature synthesis approach may offer a promising solution for the facile production of various metastable-phase 2D materials.

Method of Ga removal from a specimen on a microelectromechanical system-based chip for in-situ transmission electron microscopy

In-situ transmission electron microscopy (TEM) holders that employ a chip-type specimen stage have been widely utilized in recent years. The specimen on the microelectromechanical system (MEMS)-based chip is commonly prepared by focused ion beam (FIB) milling and ex-situ lift-out (EXLO). However, the FIB-milled thin-foil specimens are inevitably contaminated with Ga⁺ ions. When these specimens are heated for real time observation, the Ga⁺ ions influence the reaction or aggregate in the protection layer. An effective method of removing the Ga residue by Ar⁺ ion milling within FIB system was explored in this study. However, the Ga residue remained in the thin-foil specimen that was extracted by EXLO from the trench after the conduct of Ar⁺ ion milling. To address this drawback, the thin-foil specimen was attached to an FIB lift-out grid, subjected to Ar⁺ ion milling, and subsequently transferred to an MEMS-based chip by EXLO. The removal of the Ga residue was confirmed by energy dispersive spectroscopy.

Electroplated Silver-Nickel Core-Shell Nanowire Network Electrodes for Highly Efficient Perovskite Nanoparticle Light-Emitting Diodes

The low sheet resistance and high optical transparency of silver nanowires (AgNWs) make them a promising candidate for use as the flexible transparent electrode of light-emitting diodes (LEDs). In a perovskite LED (PeLED), however, the AgNW electrode can react with the overlying perovskite material by redox reactions, which limit the electroluminescence efficiency of the PeLED by causing the degradation of and generating defect states in the perovskite material. In this study, we prepared Ag-Ni core-shell NW electrodes using the solution-electroplating technique to realize highly efficient PeLEDs based on colloidal formamidinium lead bromide (FAPbBr₃) nanoparticles (NPs). Solvated Ni ions from the NiSO₄ source were deposited onto the surface of AgNW networks in three steps: (i) cathodic cleaning, (ii) adsorption of the Ni-ion complex onto the AgNW surface, and (iii) uniform electrodeposition of Ni. An ultrathin (∼3.5 nm) Ni layer was uniformly deposited onto the AgNW surface, which exhibited a sheet resistance of 16.7 Ω/sq and an optical transmittance of 90.2%. The Ag-Ni core-shell NWs not only increased the work function of the AgNW electrode, which facilitated hole injection into the emitting layer, but also suppressed the redox reaction between Ag and FAPbBr₃ NPs, which prevented the degradation of the emitting layer and the generation of defect states in it. The resulting PeLEDs based on FAPbBr₃ NPs with the Ag-Ni core-shell NWs showed high current efficiency of 44.01 cd/A, power efficiency of 35.45 lm/W, and external quantum efficiency of 9.67%.

Rapid and mass-producible synthesis of high-crystallinity MoSe2 nanosheets by ampoule-loaded chemical vapor deposition

MoSe₂ is an attractive transition-metal dichalcogenide with a two-dimensional layered structure and various attractive properties. Although MoSe₂ is a promising negative electrode material for electrochemical applications, further investigation of MoSe₂ has been limited, mainly by the lack of MoSe₂ mass-production methods. Here, we report a rapid and ultra-high-yield synthesis method of obtaining MoSe₂ nanosheets with high crystallinity and large grains by ampoule-loaded chemical vapor deposition. Application of high pressure to an ampoule-type quartz tube containing MoO₃ and Se powders initiated rapid reactions that produced vertically oriented MoSe₂ nanosheets with grain sizes of up to ∼100 μm and yields of ∼15 mg h^-1. Spectroscopy and microscopy characterizations confirmed the high crystallinity of the obtained MoSe₂ nanosheets. Transistors and lithium-ion battery cells fabricated with the synthesized MoSe₂ nanosheets showed good performance, thereby further indicating their high quality. The proposed simple scalable synthesis method can pave the way for diverse electrical and electrochemical applications of MoSe₂.

Wafer-Scale and Low-Temperature Growth of 1T-WS2 Film for Efficient and Stable Hydrogen Evolution Reaction

The metallic 1T phase of WS₂ (1T-WS₂ ), which boosts the charge transfer between the electron source and active edge sites, can be used as an efficient electrocatalyst for the hydrogen evolution reaction (HER). As the semiconductor 2H phase of WS₂ (2H-WS₂ ) is inherently stable, methods for synthesizing 1T-WS₂ are limited and complicated. Herein, a uniform wafer-scale 1T-WS₂ film is prepared using a plasma-enhanced chemical vapor deposition (PE-CVD) system. The growth temperature is maintained at 150 °C enabling the direct synthesis of 1T-WS₂ films on both rigid dielectric and flexible polymer substrates. Both the crystallinity and number of layers of the as-grown 1T-WS₂ are verified by various spectroscopic and microscopic analyses. A distorted 1T structure with a 2a₀ × a₀ superlattice is observed using scanning transmission electron microscopy. An electrochemical analysis of the 1T-WS₂ film demonstrates its similar catalytic activity and high durability as compared to those of previously reported untreated and planar 1T-WS₂ films synthesized with CVD and hydrothermal methods. The 1T-WS₂ does not transform to stable 2H-WS₂ , even after a 700 h exposure to harsh catalytic conditions and 1000 cycles of HERs. This synthetic strategy can provide a facile method to synthesize uniform 1T-phase 2D materials for electrocatalysis applications.

Characteristics of an Amorphous Carbon Layer as a Diffusion Barrier for an Advanced Copper Interconnect

The size of the advanced Cu interconnects has been significantly reduced, reaching the current 7.0 nm node technology and below. With the relentless scaling-down of microelectronic devices, the advanced Cu interconnects thus requires an ultrathin and reliable diffusion barrier layer to prevent Cu diffusion into the surrounding dielectric. In this paper, amorphous carbon (a-C) layers of 0.75-2.5 nm thickness have been studied for use as copper diffusion barriers. The barrier performance and thermal stability of the a-C layers were evaluated by annealing Cu/SiO₂/Si metal-oxide-semiconductor (MOS) samples with and without an a-C diffusion barrier at 400 °C for 10 h. Microstructure and elemental analysis performed by transmission electron microscopy (TEM) and secondary ion mass spectroscopy showed that no Cu diffusion into the SiO₂ layer occurred in the presence of the a-C barrier layer. However, current density-electric field and capacitance-voltage measurements showed that 0.75 and 2.5 nm thick a-C barriers behave differently because of different microstructures being formed in each thickness after annealing. The presence of the 0.75 nm thick a-C barrier layer considerably improved the reliability of the fabricated MOS samples. In contrast, the reliability of MOS samples with a 2.5 nm thick a-C barrier was degraded by sp² clustering and microstructural change from amorphous phase to nanocrystalline state during annealing. These results were confirmed by Raman spectroscopy, X-ray photoelectron spectroscopy and TEM analysis. This study provides evidence that an 0.75 nm thick a-C layer is a reliable diffusion barrier.

Amorphous TaxMnyOz Layer as a Diffusion Barrier for Advanced Copper Interconnects

An amorphous Ta_xMn_yO_z layer with 1.0 nm thickness was studied as an alternative Cu diffusion barrier for advanced interconnect. The thermal and electrical stabilities of the 1.0-nm-thick Ta_xMn_yO_z barrier were evaluated by transmission electron microscopy (TEM) and current density-electric field (J-E) and capacitance-voltage (C-V) measurements after annealing at 400 °C for 10 h. X-ray photoelectron spectroscopy revealed the chemical characteristics of the Ta_xMn_yO_z layer, and a tape peeling test showed that the Ta_xMn_yO_z barrier between the Cu and SiO₂ layers provided better adhesion compared to the sample without the barrier. TEM observation and line profiling measurements in energy-dispersive X-ray spectroscopy after thermal annealing revealed that Cu diffusion was prevented by the Ta_xMn_yO_z barrier. Also, the J-E and C-V measurements of the fabricated metal-oxide-semiconductor sample showed that the Ta_xMn_yO_z barrier significantly improved the electrical stability of the Cu interconnect. Our results indicate that the 1.0-nm-thick Ta_xMn_yO_z barrier efficiently prevented Cu diffusion into the SiO₂ layer and enhanced the thermal and electrical stability of the Cu interconnect. The improved performance of the Ta_xMn_yO_z barrier can be attributed to the microstructural stability achieved by forming ternary Ta-Mn-O film with controlled Ta/Mn atomic ratio. The chemical composition can affect the atomic configuration and density of the Ta-Mn-O film, which are closely related to the diffusion behavior. Therefore, the 1.0-nm-thick amorphous Ta_xMn_yO_z barrier is a promising Cu diffusion barrier for advanced interconnect technology.

Electron beam irradiation induced crystallization behavior of amorphous Ge2Sb2Te5 chalcogenide material

The crystallization of amorphous Ge₂Sb₂Te₅ phase change material induced by electron beam irradiation was investigated by in-situ transmission electron microscopy (TEM). Amorphous matrix transformed into a partially crystalline state after being irradiated with a 200-keV electron beam for a long time. Real-time observation revealed that the crystallization of amorphous Ge₂Sb₂Te₅ film occurs through a nucleation and growth mechanism under electron beam irradiation in TEM. While uncertainty from the 2D projection remains, the nuclei have been observed to grow preferentially along the < 100> direction.

Evaluation of ion/electron beam induced deposition for electrical connection using a modern focused ion beam system

Focused ion beam method, which has excellent capabilities such as local deposition and selective etching, is widely used for micro-electromechanical system (MEMS)-based in situ transmission electron microscopy (TEM) sample fabrication. Among the MEMS chips in which one can apply various external stimuli, the electrical MEMS chips require connection between the TEM sample and the electrodes in MEMS chip, and a connected deposition material with low electrical resistance is required to apply the electrical signal. Therefore, in this study, we introduce an optimized condition by comparing the electrical resistance for C-, Pt-, and W- ion beam induced deposition (IBID) at 30 kV and electron beam induced deposition (EBID) at 1 and 5 kV. The W-IBID at 30 kV with the lowest electrical resistance of about 30 Ω shows better electrical properties than C- and Pt-IBID electrodes. The W-EBID at 1 kV has lower electrical resistance than that at 5 kV; thus, confirming its potential as an electrode. Therefore, for the materials that are susceptible to ion beam damage, it is recommended to fabricate electrical connections using W-EBID at 1 kV.

Millimeter-Scale Growth of Single-Oriented Graphene on a Palladium Silicide Amorphous Film

It is widely accepted in condensed matter physics and material science communities that a single-oriented overlayer cannot be grown on an amorphous substrate because the disordered substrate randomizes the orientation of the seeds, leading to polycrystalline grains. In the case of two-dimensional materials such as graphene, the large-scale growth of single-oriented materials on an amorphous substrate has remained unsolved. Here, we demonstrate experimentally that the presence of uniformly oriented graphene seeds facilitates the growth of millimeter-scale single-oriented graphene with 3 × 4 mm² on palladium silicide, which is an amorphous thin film, where the uniformly oriented graphene seeds were epitaxially grown. The amorphous palladium silicide film promotes the growth of the single-oriented growth of graphene by causing carbon atoms to be diffusive and mobile within and on the substrate. In contrast to these results, without the uniformly oriented seeds, the amorphous substrate leads to the growth of polycrystalline graphene grains. This millimeter-scale single-oriented growth from uniformly oriented seeds can be applied to other amorphous substrates.

Investigation of Zirconium Effect on the Corrosion Resistance of Aluminum Alloy Using Electrochemical Methods and Numerical Simulation in an Acidified Synthetic Sea Salt Solution

Corrosion resistance of Zr that has been added to an Al alloy (U1070) is higher than that of a commercial Al alloy (A1070). A decreasing number and size of Al₃Fe intermetallic particles (IMPs) were observed by electron microprobe analysis and transmission electron microscopy. Based on the numerical corrosion simulation, it was confirmed that decreasing the number and size of IMPs was favorable for improving the corrosion resistance of the Al alloy due to the reduction of the galvanic effect. In addition, Al₃Zr was found to be insignificant in promoting galvanic corrosion within the Al matrix. Thus, Zr is an advantageous alloying element for improving the corrosion resistance of the Al alloy.

Quantification of crystallinity using zero-loss filtered electron diffraction

The quantity of the crystalline phases present in a nanomaterial is an important parameter that governs the correlation between its properties and microstructure. However, quantification of crystallinity in nanoscale-level applications by conventional methods (Raman spectroscopy and X-ray diffraction) is difficult because of the spatial limitations of sampling. Therefore, we propose a technique that involves using energy-filtered electron diffraction in transmission electron microscopy which offers improved spatial resolution. The degree of crystallinity (DOC) was calculated by separating the crystalline and amorphous intensities from the total intensity histogram acquired by the azimuthal averaging of the zero-loss filtered signals from electron diffraction. In order to validate the method, it was demonstrated that the DOC calculated by zero-loss filtered electron diffraction was consistent with the DOC measured by the area ratio using an amorphous silicon on crystalline silicon standard sample. In addition, the results obtained from zero-loss filtered and conventional electron diffractions were compared. The zero-loss filtered electron diffraction successfully provided the reliable results of the crystallinity quantification. In contrast, the DOC measured using conventional electron diffraction yielded extremely variable results. Therefore, our results provide a crystallinity quantification technique that can extract quantitative information about crystallinity of nanoscale devices by using zero-loss filtered electron diffraction with better reliability than conventional electron diffraction. RESEARCH HIGHLIGHTS: The degree of crystallinity can be measured by separating the crystalline and amorphous intensities from the total intensity histogram acquired by the azimuthal averaging of the zero-loss filtered signals from selected area electron diffraction.

Epitaxial-Growth-Induced Junction Welding of Silver Nanowire Network Electrodes

In this study, we developed a roll-to-roll Ag electroplating process for metallic nanowire electrodes using a galvanostatic mode. Electroplating is a low-cost and facile method for deposition of metal onto a target surface with precise control of both the composition and the thickness. Metallic nanowire networks [silver nanowires (AgNWs) and copper nanowires (CuNWs)] coated onto a polyethylene terephthalate (PET) film were immersed directly in an electroplating bath containing AgNO₃. Solvated silver ions (Ag⁺ ions) were deposited onto the nanowire surface through application of a constant current via an external circuit between the nanowire networks (cathode) and a Ag plate (anode). The amount of electroplated Ag was systematically controlled by changing both the applied current density and the electroplating time, which enabled precise control of the sheet resistance and optical transmittance of the metallic nanowire networks. The optimized Ag-electroplated AgNW (Ag-AgNW) films exhibited a sheet resistance of ∼19 Ω/sq at an optical transmittance of 90% (550 nm). A transmission electron microscopy study confirmed that Ag grew epitaxially on the AgNW surface, but a polycrystalline Ag structure was formed on the CuNW surface. The Ag-electroplated metallic nanowire electrodes were successfully applied to various electronic devices such as organic light-emitting diodes, triboelectric nanogenerators, and a resistive touch panel. The proposed roll-to-roll Ag electroplating process provides a simple, low-cost, and scalable method for the fabrication of enhanced transparent conductive electrode materials for next-generation electronic devices.

Tissue-specific expression of occludin, zona occludens-1, and junction adhesion molecule A in the duodenum, ileum, colon, kidney, liver, lung, brain, and skeletal muscle of C57BL mice

Tight junctions are the most apically positioned intercellular junction and play many roles such as securing adjacent cells, forming barriers from extracellular materials, and facilitating paracellular transport. Occludin and junction adhesion molecule A (JAM-A) are classified as transmembrane proteins that are directly involved in paracellular transport. Zona occludens-1 (ZO-1) is a protein that contains a PDZ domain which forms a binding site for other tight junction proteins. In this study, we assessed the differential expression of these tight junction components in various mouse organs including the intestine (duodenum, ileum, and colon), kidney, liver, lung, brain, and skeletal muscle. Realtime PCR and Western blot assays were performed to measure the gene and protein expression of occludin, JAM-A, and ZO-1. Similar levels of occludin gene expression were detected in all tissues except for skeletal muscle in which occludin expression was not found. The JAM-A and ZO-1 genes were highly expressed in all the tested tissues. Localization of occludin, JAM-A, and ZO-1 was determined by immunohistochemistry. These proteins were detected in the intercellular apical junctions in each tissue except for occludin (which was not observed in skeletal muscle). These immunostaining data were consistent with the gene expression profiles we obtained. Our results suggest that occludin, JAM-A, and ZO-1 genes are normally expressed in the intestine, kidney, liver, lung, and brain indicating that these factors may be essential for maintaining appropriate physiological concentration of ions, solutes and water.

Additional effects of bisphenol A and paraben on the induction of calbindin-D(9K) and progesterone receptor via an estrogen receptor pathway in rat pituitary GH3 cells

There are concerns about the combined estrogenic effects of chemicals since mixtures of these chemicals exist in our environment. This study investigated potential additional interactions between bisphenol A (BPA) and isobutylparaben (IBP), which are major xenoestrogens used in the manufacture of plastics, cosmetics, drugs, and other products. The combined effects of these two chemicals were analyzed by measuring the expression of calbindin-D(9k) (CaBP-9k) in rat pituitary cancer GH3 cells. GH3 cells were treated with single and combination doses of both chemicals (BPA single doses: 10(-7), 10(-6) and 10(-5) M; IBP single doses: 10(-7), 10(-6) and 10(-5) M, and each of the BPA and IBP doses combined). Prior to treatment, cells were temporarily transfected with a plasmid containing an ERE-luciferase reporter gene. Luciferase activity was measured as an indicator of ER activation by 17β-estradiol (E2), BPA, and IBP. BPA (10(-5) M) combined with IBP (10(-7) M and 10(-6) M) induced a significant increase in the luciferase activity. Twenty-four hours after treatment, dose-dependent effects were observed in both single and combined dose groups, and several combination doses induced significant increases in the expression of CaBP-9k and progesterone receptor (PR) at both transcriptional and translational levels. Pre-treatment with ICI 182,780, a pure estrogen antagonist, significantly reversed BPA- and IBP-induced CaBP-9k and PR upregulation in GH3 cells. Taken together, these results indicate that BPA and IBP may have additionally increased estrogenic potency via an estrogen receptor-mediated pathway.

Regulation and molecular mechanisms of calcium transport genes: do they play a role in calcium transport in the uterine endometrium?

Maintenance of calcium (Ca) balance in the uterus is critically important for many physiological functions, including smooth muscle contraction during embryo implantation. Ca transport genes, i.e., transient receptor potential cation channel subfamily V members 5/6 (TRPV5/6), calbindins, plasma membrane Ca(2+)-ATPase 1 (PMCA1), and NCX1/NCKX3, may play roles in the uterus for Ca transport and reproductive function. Although these Ca transport genes may have a role in Ca metabolism, their role(s) and molecular mechanisms require further elucidation. In this review, we highlight the expression and regulation of Ca transport genes in the uterus to clarify their potential role(s). Since Ca transport genes are abundantly expressed in reproductive tissues in a distinct manner, they may be involved in specific uterine functions including fetal implantation, Ca homeostasis, and endometrial cell production.

A cellular automaton model of cancerous growth

A cellular automaton model describing immune system surveillance against cancer is furnished. In formulating the model, we have taken into account the microscopic mechanisms of cancerous growth, such as the proliferation of cancer cells, the cytotoxic behaviors of the immune system, the mechanical pressure inside the tumor and so forth. The model may describe the Gompertz growth of a cancer. The results are in agreement with experimental observations. The influences of the proliferation rate of cancer cells, the cytotoxic rate and other relevant factors affecting the Gompertz growth are studied.