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Although graphitic-carbon nitride (gCN) is a highly investigated inorganic semiconductor, especially in the field of photocatalysis, it is still the object of many controversial discussions. The possibility to easily synthesize a homogeneous heterostructure through the condensation and the polymerization of simple molecules allows the growth of a variety of structures with different electronic and optical properties. With the aim of driving the development of the catalyst toward improved performances or newer applications, it is paramount to understand the optically-driven excitation process within each polymer. In this work, we focus on two models of melem-based gCN, i.e. the fully and the partially polymerized structures, and we perform a computational investigation, based on hybrid density functional theory calculations, of their optical properties in terms of vibrational and electronic excitations. First, we determine the normal modes of the ground state and we interpret the IR absorption spectrum. Then, we simulate the electronic excited state with an electron–hole pair model and we determine the exciton binding energy, the self-trapping energy and the photo-emission energy. We compare these numerical results with the experimental data available in literature and in addition we discuss the role of the different polymeric arrangements.

This study aimed at evaluating the influence of salt contamination on the performance of two consolidants (diammonium hydrogen phosphate, DAP, and nanolimes, NL), applied onto slaked lime-based mortars contaminated with sodium sulfate before and/or after consolidation. The strengthening ability of the two treatments was assessed in terms of dynamic elastic modulus and compressive strength by double punch test, while the alterations in the pore system were evaluated by MIP and the features of the new consolidating phases were assessed by XRD and FEG-SEM. To test the durability of the consolidated mortars, salt weathering cycles were performed by alternating immersion into a 14 wt% aqueous solution of Na2SO4·10H2O and drying in oven, as recommended by the European Standard EN 12370. The effects of the salt weathering cycles were assessed by measuring the changes in weight and dynamic elastic modulus after each cycle and the residual compressive strength after 10 cycles and desalination. The results of the study show that, right after the consolidant application, with or without salts initially present in the mortar, the strengthening ability of DAP was higher than that of NL. The DAP treatment induced formation of carbonate hydroxyapatite, as assessed by XRD, and notably the initial presence of salt inside the mortar pores did not negatively affect the outcome of the treatment. However, the formation of carbonate hydroxyapatite was responsible for a shift of the pore size distribution towards smaller pores, which may increase the stress generated by salt crystallization. When the consolidated mortar specimens were subjected to salt weathering cycles, both consolidants provided some benefit against salt weathering, but the high aggressiveness of the salt weathering test might have reduced the performance of the consolidants.

A category of naked maghemite nanoparticles (γ-Fe2O3), named surface active maghemite nanoparticles (SAMNs), is characterized by biological safety, high water colloidal stability and a surface chemistry permitting the binding of ligands. In the present study, the interaction between SAMNs and an antibiotic displaying chelating properties (oxytetracycline, OxyTC) was extensively structurally and magnetically characterized. OxyTC emerged as an ideal probe for providing insights into the colloidal properties of SAMNs. At the same time, SAMNs turned out as an elective tool for water remediation from OxyTC. Therefore, a dilute colloidal suspension of SAMNs was used for the removal of OxyTC in large volume tanks where, to simulate a real in situ application, a population of zebrafish (Danio rerio) was introduced. Interestingly, SAMNs led to the complete removal of the drug without any sign of toxicity for the animal model. Moreover, OxyTC immobilized on SAMNs surface resulted safe for sensitive Escherichia coli bacteria strain. Thus, SAMNs were able to recover the drug and to suppress its antibiotic activity envisaging their feasibility as competitive option for water remediation from OxyTC in more nature related scenarios. The present contribution stimulates the use of novel smart colloidal materials to cope with complex environmental issues.

An abnormal frontal QRS-T angle (fQRSTa) is associated with increased risk of death in primary and secondary cardiovascular prevention. The aim of this study was to evaluate the fQRSTa prognostic role in patients undergoing myocardial revascularization and/or cardiac valve surgery.We enrolled and prospectively followed for 48 ± 26 months 939 subjects with available QRS and T axis data; mean age was 68 ± 12 years, 449 patients (48%) underwent myocardial revascularization, 333 (35%) cardiac valve surgery, 94 (10%) valve plus bypass graft surgery and 63 (7%) cardiac surgery for other cardiovascular (CV) diseases. The ECG variables were collected at the end of the cardiac rehabilitation program and fQRSTa was considered normal if60°, abnormal if120°, borderline otherwise. Endpoints were overall and CV mortality.The fQRSTa was normal in 333 patients (36%), borderline in 285 (30%) and abnormal in 321 (34%). Overall (p = 0.012) and cardiovascular (p = 0.007) mortality were significantly higher in patients with abnormal fQRSTa even after adjusting separately for gender, PR-, QTc- intervals, presence of right or left bundle branch block and left atrial volume index. The predictive value was confirmed in patients with stable coronary artery disease (SCAD), not in patients with acute coronary syndrome or valve disease. SCAD patients with abnormal both fQRSTa and QRS axis had higher risk of overall (hazard ratio = 2.9, p 0.0001) and CV (hazard ratio = 4.4, p 0.0001) mortality compared with SCAD patients with normal fQRSTa, even after multivariate adjustment for age, gender, ECG intervals, left-ventricle ejection fraction and mass index.In SCAD patients undergoing myocardial revascularization, abnormal fQRSTa is independent predictor of overall and CV mortality.

The Stoppani factory manufactured chromium for more than one century, dumping millions of tons of Chromite Ore Processing Residues (COPRs) over decades. The massive presence of COPRs resulted in an intense CrVI leaching and consequent contamination of percolating groundwater. The site offers a unique opportunity to follow COPRs evolution from the primary roasting process to the aged Cr-bearing mineral phases. Herein, new insights on COPRs mineralogy evolution and their role in CrVI release are provided by a dry sample preparation protocol, coupled with in-depth multi-technique characterization. Besides typical COPRs mineral assemblages, highly soluble Na2CrO4 and the first evidence of crocoite (PbCrO4) in a COPR contaminated site are revealed. Selective extraction experiments confirmed a strong reactivity for Cr-bearing minerals as confirmed by concentrations as high as 375 mg L−1 of leached CrVI. The mineralogical approach was combined with a nanotechnological solution for CrVI wastewater remediation. The application of naked colloidal maghemite (γ-Fe2O3) nanoparticles (SAMNs) on the complex industrial wastewater, led to > 90% CrVI removal, either under acidic or in-situ conditions. The present case study of a highly polluted site, ranging from mineral characterization to wastewater remediation, highlights the use of multidisciplinary approaches to cope with complex environmental issues.

The present paper aims at comparing commercial nanolime and nanosilica dispersions with an aqueous solution of diammonium hydrogen phosphate (DAP) for consolidation of marble. The consolidants were first tested in the laboratory on artificially and naturally weathered marble specimens. The DAP-treatment applied by poulticing outperformed nanolime and nanosilica in terms of consolidating effectiveness, while showing good compatibility with the substrate. After preliminary testing of all the three consolidants on small areas of a byzantine marble sarcophagus, the DAP-treatment applied by poulticing was finally selected for application onto the whole sarcophagus. Field results confirmed the promising performance of the DAP-treatment.

Meticillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of hospital-associated infections. This study investigated the potential use of whole-genome sequencing (WGS) for surveillance purposes by re-examining MRSA strains related to past outbreaks among hospitalized paediatric patients. WGS data ameliorated the genotypic profile previously obtained with Sanger sequencing and pulsed-field gel electrophoresis typing, and discriminated between strains that were related and unrelated to the outbreaks. This allowed strain clonality to be defined with a higher level of resolution than achieved previously. This study demonstrates the potential of WGS to trace hospital outbreaks, which may lead to WGS becoming standard practice in outbreak investigations.

Metal-tetraphenyl-porphyrin (M-TPP) molecules typically self-assemble forming square-like superlattices, as dictated by their shape. The dependence of the adsorption properties on the central atom is systematically studied for Co-, Ni-, and Zn-TPP adsorbed on oxygen passivated Fe(001), namely the Fe(001)- p ( 1 × 1 ) O surface. It is found by low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) that despite the weak molecule–substrate interaction, preserving many features of quasi-free molecules, the self-assembled structure switches from the ( 5 × 5 ) R 37 ° superlattice of Co-TPP and Ni-TPP to the plain ( 5 × 5 ) of Zn-TPP. Ab initio calculations based on density functional theory (DFT) are used to investigate the adsorption properties of the different molecules and the possible overlayers formed. Adsorption energies, structures, and electronic properties are reported, discussing the bonding mechanisms and the magnetic character. Only moderate energy differences are found, suggesting that subtle effects may steer the selection of the structure among overlayers with similar properties although differing substantially as for the LEED and STM experimental results.

In this paper, the localization of structures in biomedical images is considered as a multimodal global continuous optimization problem and solved by means of soft computing techniques. We have developed an automatic method aimed at localizing the hippocampus in histological images, after discoveries indicating the relevance of structural changes of this region as early biomarkers for Alzheimer's disease and epilepsy. The localization is achieved by searching the parameters of an empirically-derived deformable model of the hippocampus which maximize its overlap with the corresponding anatomical structure in histological brain images. The comparison between six real-parameter optimization techniques (Levenberg-Marquardt, Differential Evolution, Simulated Annealing, Genetic Algorithms, Particle Swarm Optimization and Scatter Search) shows that Differential Evolution significantly outperforms the other techniques in this task, providing successful localizations in 90.9% and 93.0% of two test sets of real and synthetic images, respectively.

Background Human cytomegalovirus (HCMV) is an opportunistic pathogen especially for immuno-suppressed subjects that might develop pharmacological resistance in patients undergoing prolonged antiviral treatment. Ganciclovir (GCV) is the drug used as first choice therapy in affected children and a GCV-resistant phenotype is mainly linked to mutations of the viral protein kinase UL97. Objectives Here a new quantitative pyrosequence (PSQ) method is presented that allows detection and quantification of the viral species carrying the more frequent UL97 mutations responsible for GCV resistance in clinical samples (>80% of known cases). Study design The system has been validated using two independent approaches (cloning and sequencing of UL-97 gene fragments and real-time PCR) and clinical samples derived from 3 pediatric patients. Results The UL97 pyrosequencing analysis has indicated a significant increase of mutant viruses carrying the H520Q and C592G mutations. In particular, the H520Q viral mutation, known to increase GCV resistance (IC50 = 10) increased around 5 times during hospitalization. In addition, C592G (known to have IC50 = 2.9) also increased 3 times. Conclusions PSQ is a quick, cheap, high throughput and sensitive analysis method to detect GCV-associated resistance mutation useful to follow antiviral therapy in perinatal CMV-infection as well as in immune-suppressed patients.

A low threshold Cr:LiSAF laser pumped with an inexpensive single-mode laser diode emitting 120 mW was passively mode-locked with a novel ultrafast saturable absorber mirror based on single-walled carbon nanotubes (SWCNT-SAM). Pulses as short as 122 fs were achieved, tunable across 14 nm. A second pump diode coupled in polarization allowed to shorten the pulse duration to 106 fs, with up to 24-mW output power.

Treatment of R2Si(C C-SiMe3)2 [1a (Me), 1b (Ph)] with HB(C6F5)2 at low temperature (253 K (a), 273 K (b)) gives the –B(C6F5)2 substituted silacyclobutene products (4a,b) under kinetic control. Upon warming to room temperature they disappear to form the thermodynamically favoured isomeric silole derivatives (2a,b). Similar treatment of Me2Si(C C–R1)2 [5a (R1 = Ph), 5b (R1 = tert-butyl) with HB(C6F5)2 at room temperature gave the stable –B(C6F5)2 substituted silacyclobutene derivatives 6 and 7, respectively. Subsequent photolysis resulted in a Z- to E-isomerization of the substituted exocyclic C C double bonds in these products. The silacyclobutene derivative E-6 was characterized by an X-ray crystal structure analysis.

A measurement of the flux of neutrino-induced muons using the MACRO detector is presented. Different event topologies, corresponding to different neutrino parent energies can be detected. The upward throughgoing muon sample is the larger event sample. The observed upward-throughgoing muons are 26% fewer than expected and the zenith angle distribution does not fit with the expected one. Assuming neutrino oscillations, both measurements suggest maximum mixing and Dm2 of a few times 10-3 eV2. The other samples are due to the internally produced events and to upward-going stopping muons. These data show a regular deficit of observed events in each angular bin, as expected assuming neutrino oscillations with maximum mixing, in agreement with the analysis of the upward-throughgoing muon sample., Comment: 7 pages 6 figures to appear in the proceedings of XVIII International Conference on Neutrino Physics and Astrophysics (Neutrino'98), Takayama, Japan 4-9 June, 1998

Rationale and Objectives This study was performed to evaluate the relationship between dose levels of contrast medium and image quality in magnetic resonance (MR) angiography of the carotid arteries with fluoroscopically monitored, manually triggered, elliptically ordered image acquisitions. Materials and Methods Twenty-five patients with clinical indications for angiography of the carotid arteries were examined with MR at 1.5 T by using a fluoroscopically monitored, manually triggered, elliptically ordered pulse sequence with the administration of one of three different volumes of gadolinium-based contrast medium. The signal intensities of the vessel lumen and the surrounding tissues were measured in single partitions at the origin of the common carotid artery, the carotid bifurcation, and the intracranial internal carotid arteries. The contrast-to-noise ratio in these regions of interest also was measured. Maximum intensity projection image quality was appraised for blurring, artifacts, venous enhancement, background suppression, and contrast medium distribution. Results No artifacts or venous enhancement was observed. The position of the fluoroscopic section affected the distribution of contrast medium along the vessel, as evidenced by the difference between the contrast-to-noise ratio at the origin of the common carotid artery and the ratio at the carotid bifurcation and the intracranial internal carotid arteries (P < .01). The contrast medium dose administered was strongly correlated with image quality (r = 0.90). Conclusion Contrast medium dose is related to image quality in MR angiography of the carotid arteries performed with elliptical ordering, fluoroscopic monitoring, and manual triggering.

The contrast timing is crucial in fast imaging magnetic resonance (MR), particularly in the angiographic techniques. In MR sequences the central lines of k space own the image contrast information (1,2). Hence, the synchronization of the acquisition of central views of k-space during the maximum concentration of contrast media (CM) into the examined vessel is mandatory to obtain images of higher quality (2–7). The lack of adequate timing with premature acquisition yields to poor examination with no visualization of the vessels. On the opposite, the continuous infusion or a delayed acquisition cause the enhancement of veins and soft tissues that may obscure the examined structures (5, 8–11). In fact, although fast imaging sequences increase the image quality and lessen the contrast media injected volume, a shorter acquisition time allows a smaller error in contrast timing (6, 10). Additional factors occurs with high flow vessels such as renal and carotid arteries in which the window of selective enhancement is very narrow (4, 10–13). The delay of the scan is not accurately predicted by patient’s physiological parameters (3, 7, 12). Several techniques have been developed to ensure a proper timing (14). The first one is based on a test bolus administered prior to angiographic acquisition during continuous monitoring scans at the level of the region of interest. The scan delay is estimated from the measurement of the transit time of the test bolus from the site of injection to the examined vessel (3, 7, 12, 15). The second technique is based on a series of consecutive short angiographic sequences expecting that the vessels of interest fill at least during the central period of one of them (16, 17). The third one consists on partial k-space updating with increased time resolution through more frequent sampling of the k-space’s centre (5, 14, 18). All these techniques suffer from several drawbacks because of the inverse relationship between the spatial resolution and the acquisition time. Moreover they are less accurate in high flow vessels. Magnetic resonance angiography (MRA) with centric ordered acquisition is a relatively new technique which has been already investigated by several Authors (6, 10, 13, 19– 22). Basically in this technique the central views of k-space are acquired at the very beginning of the acquisition. The triggering is automatic or manual as the vessel enhancement is detected through an automatic volume sampling with a threshold or through a monitoring “fluoroscopic” slice. The asymmetric structure of this sequence and the advantages on contrast timing lead to a different use of the contrast media. The aim of this study is to assess the influence of the contrast media dose in MRA with elliptical ordering of the carotid arteries and to identify the parameters affecting this technique.

Studies using single photon emission computed tomography (SPECT) have found low cerebral blood flow (CBF) in frontal and parietal cortices in patients with chronic opiate dependence. In the present study, SPECT with 99mTc-HMPAO as tracer was used to compare 27 detoxified opiate addicts with nine healthy control subjects. All the subjects were evaluated with clinical psychiatric (DSM-IV), psychometric and neuropsychological measures. Compared with normal control subjects, the addicts showed a non-significant reduction of whole brain perfusion values. Significant hypoperfusion in the right frontal and left temporal lobes was found in addicts with comorbid depression, and a significant decrease in CBF in the right frontal lobe was observed in those with antisocial tendencies. A significant negative correlation emerged between Depression subscale scores on the Minnesota Multiphasic Personality Inventory and left temporal CBF in the patients. No significant correlations were found, however, between measures of cognition and CBF in opiate addicts. The asymmetrical findings in CBF that characterized the addicts relative to normal control subjects may be more closely related to mood and behavioral traits than to substance abuse, per se.

Aim of this randomized, double-blind, parallel group study was to compare the safety, tolerance and diagnostic efficacy of iomeprol and iopamidol, both at iodine concentration of 150 mgI/ml, in 100 adult patients undergoing peripheral intra-arterial digital subtraction angiography (IA-DSA). All patients underwent extensive pre- and post-contrast clinical, instrumental and laboratory evaluation for safety assessments. The tolerance to the test compounds was evaluated in terms of discomfort associated with the injection of the test compounds. Image quality was prospectively graded by two independent readers according to a five-point scale as 1, insufficient; 2, sufficient; 3, good; 4, excellent; or E, excessive. At the end of the study, two experienced radiologists working at institutions other than the study centre and not aware of patients identity, clinical profile or results of other imaging procedures, jointly evaluated study images using the same ordinal scale. The procedure was always well tolerated. None of the studied patients experienced adverse events. All angiographic examinations were rated as diagnostic. The quality of the radiographs was judged as excellent or good in most individual patient studies, without significant differences between the two study groups. No significant differences between the results of prospective on-site assessment and retrospective external assessment were detected. The results of our study show that iomeprol and iopamidol are equally effective, well tolerated and safe contrast agents when used for peripheral IA-DSA.