Ultrasonic study of water adsorbed in nanoporous glasses.

Thermodynamic properties of fluids confined in nanopores differ from those observed in the bulk. To investigate the effect of nanoconfinement on water compressibility, we perform water sorption experiments on two nanoporous glass samples while concomitantly measuring the speed of longitudinal and shear ultrasonic waves in these samples. These measurements yield the longitudinal and shear moduli of the water-laden nanoporous glass as a function of relative humidity that we utilize in the Gassmann theory to infer the bulk modulus of the confined water. This analysis shows that the bulk modulus (inverse of compressibility) of confined water is noticeably higher than that of the bulk water at the same temperature. Moreover, the modulus exhibits a linear dependence on the Laplace pressure. The results for water, which is a polar fluid, agree with previous experimental and numerical data reported for nonpolar fluids. This similarity suggests that irrespective of intermolecular forces, confined fluids are stiffer than bulk fluids. Accounting for fluid stiffening in nanopores may be important for accurate interpretation of wave propagation measurements in fluid-filled nanoporous media, including in petrophysics, catalysis, and other applications, such as in porous materials characterization.

A Strong Test of Atomically Detailed Models of Molecular Adsorption in Zeolites Using Multilaboratory Experimental Data for CO2 Adsorption in Ammonium ZSM-5.

A recent international interlaboratory study led by the U.S. National Institute of Standards (NIST) reported CO2 adsorption isotherms measured independently by 11 groups on reference material RM 8852, an ammonium ZSM-5 zeolite. Good reproducibility and high reliability of this experimental data provide a strong test for the ability of atomically detailed models to predict adsorption of CO2 in zeolites. We developed force fields for CO2 in ammonium zeolites based on first-principles calculations and also independently performed experiments with RM 8852 by microcalorimetry. At low pressures good agreement was obtained between predictions and experiments. At high pressures, however, deviations were observed. We show that the charge-balancing cations in the experimental material are the predominant source of the discrepancy between simulation and experiment at high pressures; the experimental sample treatment causes deammoniation. In addition, accounting for a small amount of noncrystalline mesoporosity in the zeolite brings predictions into much better agreement with experiments.

Endoscopic therapy of superficial bladder cancer in high-risk patients: Holmium laser versus transurethral resection.

Many lasers are widely used in urological surgery for several applications. Their use to treat the superficial bladder cancer (SBC) is safe and minimally invasive. The Holmium:YAG (Ho:YAG) laser represents the pinnacle of laser technology in Urology. The authors carried out this study on safety, efficacy, complication rates, postoperative catheterization time, and hospital stay of high-risk patients who underwent Ho:YAG vs. transurethral resection (TUR). Two groups of high-risk patients with SBC and comorbidities underwent either Ho:YAG or TUR. Different clinical aspects of the tumours and recurrences were considered. No significant difference between the two groups was noted regarding number, progression of grade and stage and place and time of recurrences. In the Ho:YAG patients, perioperative complications occurred at a lower percent than in the TUR group. Also, in 54% of patients, the catheter was removed within 24 hours; 76% had a postoperative hospital stay of 24 to 48 hours. In the TUR patients: 4% had the catheter removed within 24 hours and 6% left the hospital within 24 to 48 hours. In SBC treatment, Ho:YAG and TUR were equally as effective; the Ho:YAG laser was associated with shorter catheterization time and hospital stay. These Ho:YAG features could be advantageous from a psychological standpoint, particularly for elderly, high-risk patients and in terms of cost:benefit ratios.

[Role of 3D-ultrasonography in the assessment of transitional zone PSA]. / Il ruolo dell'ecografia 3d nella valutazione del PSA TZ.

OBJECTIVE: Valute 3 TRUS to study the transitional zone of the prostate to calculate the PSA density Tz in patient with first negative biopsy, PSA Tot > 4 ng/ml and clinical suspicion of cancer. METHODS: During a 12 months period we performed 429 biopsies. All patients had PSA = 4-10 ng/ml and/or suspected DRE. We repeated biopsy in 35 patients with PSA > 4 ng/ml, normal DRE but clinical suspicion of cancer. We used 3 TRUS to calculate the PSA density Tz and we performed standard sextant biopsies and additionally two biopsies of the transitional zone one on each side. RESULTS: Of the 429 patients, 304 (70.8%) had IPB, 100 (23.3%) had cancer in peripherical and/or apex zone, 25 (5.9%) cancer in the transitional zone only. CONCLUSIONS: The use of 3 DUS is very important to study and estimate the volume of the transitional zone to calculate the PSA density Tz. The clear visualization of the Tz permit a careful execution of the biopsy. The biopsy of the TZ is not a method for the early detection to cancer prostate but only for specifics cases: negative first biopsy, negative DRE, PSA Tot > 4 ng/ml and clinical suspicion of cancer.