Pt/MnO Interface Induced Defects for High Reverse Water Gas Shift Activity.

The implementation of supported metal catalysts heavily relies on the synergistic interactions between metal nanoparticles and the material they are dispersed on. It is clear that interfacial perimeter sites have outstanding skills for turning catalytic reactions over, however, high activity and selectivity of the designed interface-induced metal distortion can also obtain catalysts for the most crucial industrial processes as evidenced in this paper. Herein, the beneficial synergy established between designed Pt nanoparticles and MnO in the course of the reverse water gas shift (RWGS) reaction resulted in a Pt/MnO catalyst having ≈10 times higher activity compared to the reference Pt/SBA-15 catalyst with >99 % CO selectivity. Under activation, a crystal assembly through the metallic Pt (110) and MnO evolved, where the plane distance differences caused a mismatched-row structure in softer Pt nanoparticles, which was identified by microscopic and surface-sensitive spectroscopic characterizations combined with density functional theory simulations. The generated edge dislocations caused the Pt lattice expansion which led to the weakening of the Pt-CO bond. Even though MnO also exhibited an adverse effect on Pt by lowering the number of exposed metal sites, rapid desorption of the linearly adsorbed CO species governed the performance of the Pt/MnO in the RWGS.

The growth and thermal properties of Au deposited on Rh(111): formation of an ordered surface alloy.

Scanning tunnelling microscopy (STM), low energy ion scattering spectroscopy (LEIS), X-ray photoelectron spectroscopy (XPS) and high resolution electron energy loss spectroscopy (HREELS) were applied for studying Au deposited on the Rh(111) surface. Both the deposition of Au at different substrate temperatures (400-800 K) and the effect of annealing Au deposited at 500 K were investigated. Gold deposition at 500 K, investigated by STM and LEIS methods, revealed that up to half monolayer Au the system exhibits clearly layer-by layer growth; however, above this coverage a slight deviation was identified, mainly due to kinetic and morphological effects. A continuous cover layer of Au was formed only above ∼2.5 monolayers (ML). Below this coverage, the pseudomorphic character of the Au overlayer was clearly proven by STM, but this feature disappears at 4 ML coverage. A moderate (5-10%) surface mixing of the two metals was observed only above 600 K, for both annealing the Au layer formed at lower temperatures and performing the deposition at elevated temperatures. Above 600 K a clear step-flow growth mechanism was verified. Depending on the Au coverage, a more extended mixing of the top layer and the sublayer was observed at even higher temperatures. In this case, nano-range ordering of the alloyed layer was detected by STM, where the lateral extension of the uniform commensurate (2 × 1) domains was around 4 × 4 nm2. In this case, the local intralayer mixing of Rh and Au can locally reach a value of 50%. The proposed structural model for the (2 × 1) alloy phase was also corroborated by HREELS investigations on CO adsorption.

Adsorption and switching properties of a N-benzylideneaniline based molecular switch on a Au(111) surface.

High resolution electron energy loss spectroscopy has been employed to analyze the adsorption geometry and the photoisomerization ability of the molecular switch carboxy-benzylideneaniline (CBA) adsorbed on Au(111). CBA on Au(111) adopts a planar (trans) configuration in the first monolayer (ML) as well as for higher coverages (up to 6 ML), in contrast to the strongly nonplanar geometry of the molecule in solution. Illumination with UV light of CBA in direct contact with the Au(111) surface (1 ML) pronounced modifications of vibrational features were observed, which we assign to a trans-->cis isomerization. Thermal activation induced the back reaction to trans-CBA. We propose that the photoisomerization is driven by a direct (intramolecular) electronic excitation of the adsorbed CBA molecules in the second ML (and above) analogous to CBA in the liquid phase.

Double probing individual human spermatozoa: aniline blue staining for persistent histones and fluorescence in situ hybridization for aneuploidies.

OBJECTIVE: To study the potential relationship between two sperm nuclear attributes: persistence of histones and occurrence of chromosomal aneuploidies. DESIGN: The two variables were examined by double probing of the same spermatozoa. SETTING: Academic Andrology Laboratory. PATIENT(S): Semen samples subjected for analyses were examined. INTERVENTION(S): We studied >58,000 spermatozoa, in seven men, first with aniline blue histone staining, graded as light (mature sperm), intermediate (moderately immature), and dark (severely arrested maturation). After recording the staining patterns and destaining, the same spermatozoa were subjected to fluorescence in situ hybridization (FISH), using centrometric X, Y, and 17 chromosome probes. MAIN OUTCOME MEASURE(S): Proportions of sperm with light, intermediate, and dark staining were assessed, and ploidy of these sperm was evaluated. RESULT(S): The aneuploidy frequencies in intermediate versus light (mature) spermatozoa were increased four- to sixfold. In addition, aneuploidy frequencies and proportions of intermediate sperm were related. There was no FISH signal detectable in the darkly stained, severely arrested mature sperm. CONCLUSION(S): The data suggest that in sperm with arrested maturity and DNA fragmentation, the binding of FISH probes is diminished. DNA damage is further aggravated by the decondensation and denaturation steps of FISH. Thus, there is a strong likelihood that in oligozoospermic men, with a higher proportion of sperm with arrested maturation, the sperm disomy frequencies are historically underestimated.

Acute effect of cigarette smoking on placental circulation - a study by carbon-monoxide measurement and Doppler assessment.

OBJECTIVE: Carbon-monoxide (CO) decreases placental vascular impedance. We assessed the consequences of smoking-induced temporary maternal CO-increase on fetal and placental circulation. STUDY DESIGN: In a prospective study twenty-nine smoking pregnant women and their fetuses were evaluated. We determined the changes in maternal blood CO levels after smoking, and the concomitant changes in maternal and fetal circulation. Changes in fetal heart rate, uterine artery (UTA), middle cerebral artery (MCA), and descending aorta (DA) flow were measured by Doppler velocimetry. Changes in maternal CO level and umbilical flow value were assessed by paired t-test. The correlation between CO level and placental flow was assessed by partial correlation test. RESULTS: CO level increased (mean +/-SD 1.7 +/- 0.065% vs. 2.36 +/- 0.89, p<0.0001). Nicotine-related maternal circulatory parameters changed significantly, but uterine flow values remained unchanged. Fetal heart rate increased, while flow in MCA and DA showed no change. CO-dependent umbilical artery impedance remained unchanged (Pulsatility Index: 0.956 +/- 0.18 vs. 0.948 +/- 0.21). Partial correlation between CO level and umbilical arterial impedance showed no significance (r:-0.324). CONCLUSION: Despite significant CO elevation, the mainly CO-regulated placental flow remained unchanged.

Double probing of human spermatozoa for persistent histones, surplus cytoplasm, apoptosis and DNA fragmentation.

Individual spermatozoa were assessed with pairs of probes for persistent histones and cytoplasmic retention, persistent histones and DNA fragmentation, and persistent histones and apoptotic markers. The individual spermatozoa were treated sequentially with combinations of probes for these cytoplasmic and nuclear biochemical markers. Sperm fields were recorded with computer-assisted imaging, and staining patterns with the two probes in the same spermatozoa were examined and scored as light, intermediate or dark (mature to arrested-maturity spermatozoa). The effects of arrested sperm maturation were similar with respect to the cytoplasmic and nuclear characteristics of spermatozoa in 84% of cells, indicating that cytoplasmic and nuclear attributes of arrested sperm maturation are related. However, there were moderate (intermediate-dark or intermediate-light patterns, 14.5% of cells) or major (light-dark patterns, 1.6% of cells) discrepancies in the intensity of the double staining patterns. Thus, testing with single maturity markers may not be fully reliable. These findings are important with respect to: (i) arrested sperm maturation; (ii) potential efficacy of antioxidant and similar therapeutic strategies in subfertile men, as spermatozoa with infrastructure defects due to mismaturation or maturation arrest are unlikely to respond to interventions; and (iii) detection of adverse male environmental exposures.

Dimensional assessment of X-bearing and Y-bearing haploid and disomic human sperm with the use of fluorescence in situ hybridization and objective morphometry.

OBJECTIVE: To explore the dimensional attributes of haploid and disomic X-bearing and Y-bearing spermatozoa. DESIGN: Morphometric evaluation of more than 2,000 X-bearing and Y-bearing spermatozoa after identification of the genotype with fluorescence in situ hybridization. SETTING: Academic clinical and research andrology laboratory. MAIN OUTCOME MEASURE(S): Sperm head area, perimeter, long axis, short axis, shape factor, elliptical form factor (long axis/short axis), and tail length. RESULT(S): We found no differences in dimensions or dimensional distributions between X-bearing and Y-bearing spermatozoa, whether in the native or the decondensed state, or in oligozoospermic or normozoospermic men. There were inconsistent differences and a 70% overlap in the dimensions of haploid and disomic spermatozoa. The other 30% of sperm with disomic nuclei were either smaller or larger compared to haploid spermatozoa. CONCLUSION(S): There are no differences, or distinguishing characteristics, in dimensions or dimensional distributions between X-bearing and Y-bearing spermatozoa. Dimensional attributes do not discriminate between dysomic and haploid spermatozoa.

Detection of feeding artery improves the ultrasound diagnosis of endometrial polyps in asymptomatic patients.

OBJECTIVE: To investigate whether transvaginal power Doppler imaging of the vascularity improves the ultrasound detection rate of endometrial polyps in symptomatic and asymptomatic patients. STUDY DESIGN: Forty-one patients with endometrial polyps confirmed by operative hysteroscopy and histologic examination. They were all examined with grey-scale and subsequent power Doppler enhanced ultrasound preoperatively according to the same protocol. Double layer endometrium and detailed endometrial morphology were described at grey scale scan. With power Doppler imaging pattern of endometrial vascularity. In the presence of a single feeding artery the ultrasound diagnosis of an endometrial polyp was made. RESULTS: With grey-scale imaging 20 polyps (49%) were recognized, while the subsequent application of power Doppler diagnosed the remaining 21 polyps increasing the overall detection rate to 10% (P < 0.01). The grey-scale detection rate for the polyp was 11/30 (0.37) in the asymptomatic patients and 9/11 (82%) in the symptomatic patients. No difference in endometrial thickness was observed. With power Doppler imaging, the detection rate for the feeding arteries was 97% (29/30) in the asymptomatic polyps and a similar 91% (10/11) in the symptomatic polyps. In the 21 polyps, where imaging of the vascularity was the only diagnostic marker, all but two were asymptomatic. CONCLUSION: Power Doppler enhanced ultrasound detection of the feeding vessels can be a simple, non-invasive and highly effective first line test for the diagnosis of endometrial polyps in asymptomatic patients.

Surface and subsurface oxidation of Mo2C/Mo(100): low-energy ion-scattering, auger electron, angle-resolved X-ray photoelectron, and mass spectroscopy studies.

The interaction of oxygen with a carburized Mo(100) surface was investigated at different temperatures (300-1000 K). The different information depths of low-energy ion-scattering (LEIS) spectroscopy, with topmost layer sensitivity, Auger electron spectroscopy (AES), and angle-resolved X-ray photoelectron spectroscopy (ARXPS) allowed us to discriminate between reactions on the topmost layer and subsurface transformations. According to ARXPS measurements, a carbide overlayer was prepared by the high-temperature decomposition of C(2)H(4) on Mo(100), and the carbon distribution proved to be homogeneous with a Mo(2)C stoichiometry down to the information depth of XPS. O(2) adsorbs dissociatively on the carbide layer at room temperature. One part of the chemisorbed oxygen is bound to both C and Mo sites, indicated by LEIS. Another fraction of oxygen atoms probably resides in the hollow sites not occupied by C. The removal of C from the outermost layer by O(2), in the form of CO, detected by mass spectroscopy (MS), was observed at 500-600 K. The carbon-depleted first layer is able to adsorb more oxygen compared to the Mo(2)C/Mo(100) surface. Applying higher doses of O(2) at 800 K results in the inward diffusion of O and the partial oxidation of Mo atoms. This process, however, is not accompanied by the removal of C from subsurface sites. The depletion of C from the bulk starts only at 900 K (as shown by MS, AES, and XPS), very probably by the diffusion of C to the surface followed by its reaction with oxygen. At T(ads) = 1000 K, the carbon content of the sample, down to the information depth of XPS, decreased further, accompanied by the attenuation of the C concentration gradient and a substantially decreased amount of oxygen.

[Ultrasound diagnosis of focal intrauterine lesions]. / Méhen belüli körülírt elváltozások ultrahang-diagnosztikája.

OBJECTIVE: To compare the efficacy of the conventional grey-scale real time ultrasound, color Doppler ultrasound (color flow mapping) and hysteroscopy in the diagnosis of circumscript intrauterine lesions, such as endometrial polyps and submucosal myomas. METHODS: Preoperative transvaginal ultrasound data of 124 patients with focal intrauterine lesions, as confirmed by operative hysteroscopy, were elaborated. Using grey-scale ultrasound the detailed endometrial morphology, with color Doppler the vascularization pattern of the endometrium was examined. The ultrasound diagnosis, the hysteroscopic diagnosis and the histological diagnosis were matched and the sensitivity of conventional grey-scale ultrasound, color Doppler ultrasound and hysteroscopy were calculated. Age, menstrual and fertility status, medication and symptoms (abnormal bleeding) of patients were also evaluated. RESULTS: Of the 124 removed lesions the histological examination confirmed 114 endometrial polyps and 10 leiomyomas. Conventional grey-scale ultrasound was performed at 79 patients (TVS group), while 45 patient were examined by color Doppler ultrasound (TVCD group). In the TVS group the intrauterine lesion was detected in 59 cases, and the origin was also correctly diagnosed in 48 cases. In the TVCD group 42 lesions were detected, and the ultrasound diagnosis was consistent with the histological diagnosis in 41 cases. At hysteroscopy 118 endometrial polyps and 6 myoma were described. In this material the sensitivity of conventional transvaginal grey-scale ultrasound, the color Doppler ultrasound, and hysteroscopy in the detection of circumscript intrauterine lesions was 0.74, 0.93 and 1, respectively; in the diagnosis of the intrauterine lesion was 0.66, 0.91 and 0.97, respectively. Statistically significant differences were found between the ultrasound detection rates (p < 0.05) and between the diagnosis rates (p < 0.01) of the TVS and the TVCD group. Abnormal menopausal bleeding, recurrent bleeding, infertility, and tamoxifen therapy were present with high frequency in clinical data. CONCLUSION: Visualization of the feeding vessels using color or power Doppler ultrasound imaging improves the detection rate and the ultrasound diagnosis of the circumscript intrauterine lesions, approaching the sensitivity of hysteroscopy. First line application is recommended for patients at risk, such as infertility, recurrent postmenopausal bleeding, or for patients receiving long term tamoxifen.