In Situ Transmission Electron Microscopy Observation of Silver Oxidation in Ionized/Atomic Gas

The interaction between silver and ionized and atomic gas was observed directly by in situ transmission electron microscopy with an environmental cell for the first time. The electron beam provides dual functions as the source of both gas ionization and imaging. The concentration of ionized gas was tuned via adjusting the current density of the electron beam. Oxidation of the silver is observed in situ, indicating the presence of ionized and/or atomic oxygen. The evolution of microstructure and phase constituents was characterized. Then the oxidation rate was measured, and the relationships among grain size, mass transport rate, and electron flux were characterized. The role of the electron beam is discussed, and the results are rationalized with respect to ex situ results from the literature

In Situ Transmission Electron Microscopy Observation of Silver Oxidation in Ionized/Atomic Gas

The interaction between silver and ionized and atomic gas was observed directly by in situ transmission electron microscopy with an environmental cell for the first time. The electron beam provides dual functions as the source of both gas ionization and imaging. The concentration of ionized gas was tuned via adjusting the current density of the electron beam. Oxidation of the silver is observed in situ, indicating the presence of ionized and/or atomic oxygen. The evolution of microstructure and phase constituents was characterized. Then the oxidation rate was measured, and the relationships among grain size, mass transport rate, and electron flux were characterized. The role of the electron beam is discussed, and the results are rationalized with respect to ex situ results from the literature

Metastability and Structural Polymorphism in Noble Metals: The Role of Composition and Metal Atom Coordination in Mono- and Bimetallic Nanoclusters

This study examines structural variations found in the atomic ordering of different transition metal nanoparticles synthesized <i>via</i> a common, kinetically controlled protocol: reduction of an aqueous solution of metal precursor salt(s) with NaBH₄ at 273 K in the presence of a capping polymer ligand. These noble metal nanoparticles were characterized at the atomic scale using spherical aberration-corrected scanning transmission electron microscopy (C_s-STEM). It was found for monometallic samples that the third row, face-centered-cubic (fcc), transition metal [(3M)Ir, Pt, and Au] particles exhibited more coherently ordered geometries than their second row, fcc, transition metal [(2M)Rh, Pd, and Ag] analogues. The former exhibit growth habits favoring crystalline phases with specific facet structures while the latter samples are dominated by more disordered atomic arrangements that include complex systems of facets and twinning. Atomic pair distribution function (PDF) measurements further confirmed these observations, establishing that the 3M clusters exhibit longer ranged ordering than their 2M counterparts. The assembly of intracolumn bimetallic nanoparticles (Au–Ag, Pt–Pd, and Ir–Rh) using the same experimental conditions showed a strong tendency for the 3M atoms to template long-ranged, crystalline growth of 2M metal atoms extending up to over 8 nm beyond the 3M core

Age-Dependent Sex Hormone-Binding Globulin Expression in Male Rat

<div><p></p><p>Sex hormone binding globulin (SHBG) is known as a carrier protein, classically thought to be mainly synthesized in the liver and then secreted into the circulating system, where it binds to sex steroids with a high affinity and modulates the bioavailability of these hormones. In humans, the organs other than the liver known to produce SHBG include the brain, uterus, testis, prostate, breast and ovary, and the locally expressed SHBG is considered to play an important role in various physiological and pathological processes. A few studies of SHBG in rats were reported, but systemic SHBG studies in consideration of different organs and aging are currently missing. So we examined the SHBG expression in the brain, liver, prostate, and serum in 40 Sprague–Dawley male rats in four different groups (newborn, 2, 6, and 12 months old, respectively) with 10 in each group by immunohistochemistry, immunofluorescience microscopy, qRT-PCR, ELISA, western blotting, and laser confocal microscopy. We discovered that SHBG was increasingly expressed in all the three tissues along with age, and the SHBG protein expression was observed in the cytoplasm and membrane of neurons, hepatocyte, and prostate epithelial cells. The ELISA assay of the sera also supported an increasing SHBG level along with age. It is concluded that the locally synthesized SHBG in the liver, brain, and prostate and the circulating SHBG of male SD rats are positively associated with age, further indicating a potential role of SHBG in aging.</p></div

Stem-like phenotype analyses by flow cytometry.

<p>(A–C) CD44, CD24 and CD90 expressions were analyzed by flow cytometry in LNCaP and PC-3 cells cultivated with/without DHT in 10 nM for 48 hours. CD44 was induced by DHT treatment in both cell lines (A). No statistically significant difference of CD24 expression level was shown in both cell lines (B). CD90 expression was significantly increased by DHT stimulation in both cell lines (C). (* means <i>P</i><0.05).</p

DHT upregulates AR expression and increases PSA secretion in LNCaP cells.

<p>(<b>A</b>) DHT upregulates AR expression in LNCaP cells in both time-dependent and concentration-dependent manners (left panel); there are also higher levels of PSA in the DHT treated cells revealed by the ELISA method (right panel). (<b>B</b>) Immunocytochemistry shows nuclear positivity of AR in LNCaP cells and its expression is upregulated by DHT treatment; but AR expression is negative in the PC-3 cells with/without DHT treatment (bar scale: 50 µm).</p

Immunohistochemistry of SHBG expression in prostate cancer tissues.

<p>(A) Positive and negative control of SHBG in liver tissues. (B) Weak SHBG positivity is shown in a benign prostate tumor and strong SHBG immunoreactivity is revealed in a malignant Gleason score 8 cancer tissue. (C) Representative immunohistochemical images of different scores of prostate cancer samples are shown. Bar scale in all of the images is 150 µm.</p

Clinical and pathologic characteristics for 117 patients with malignant prostate cancer.

<p>PSA, prostatic specific antigen.</p

DHT induces cell growth and clonogenicity in prostate cancer cell lines.

<p>(A) Cell growth curves show statistically significant difference in LNCaP cells with/without DHT treatment, but not in PC-3 cells (* means <i>P</i><0.05). (B) Representative photographs of colony formation in both cell lines demonstrate that more colonies were formed by 1 nM DHT treatment and even more colonies were obtained by 10 nM DHT treatment (bar scale: 50 mm). (C) Histograms of colony formation efficiency show statistically higher efficiencies in the cells treated with low concentration of DHT (<i>P</i><0.01), and even higher efficiencies in the cells by high concentration of DHT (<i>P</i><0.001). (D) Representative photographs for sphere formation for both cell lines in the cells with/without DHT treatment (bar scale: 50 µm). (E) Histograms for sphere formation efficiency show higher efficiencies in the cells added with 1 nM DHT (<i>P</i><0.05), and even higher efficiencies in the cells stimulated with 10 nM DHT (<i>P</i><0.01).</p