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D Bono

Publications and source records attributed to D Bono.

At least 19 recordsLinked to original sources
PubMed2006

Muon spin relaxation studies of superconductivity in a crystalline array of weakly coupled metal nanoparticles.

We report muon-spin-relaxation studies in weak transverse fields of the superconductivity in the metal cluster compound, Ga84[N(SiMe3)2]20-Li6Br2(thf)20.2 toluene. The temperature and field dependence of the muon-spin-relaxation rate and Knight shift clearly evidence type II bulk superconductivity below Tc approximately 7.8 K, with Bc1 approximately 0.06 T, Bc2 approximately 0.26 T, kappa approximately 2, and weak flux pinning. The data are well described by the s-wave BCS model with weak electron-phonon coupling in the clean limit. A qualitative explanation for the conduction mechanism in this novel type of narrow-band superconductor is presented.

Journal Article↗
PubMed2006

Neutron spin-echo investigation of slow spin dynamics in kagomé-bilayer frustrated magnets as evidence for phonon assisted relaxation in SrCr9xGa12-9xO19.

A neutron spin-echo investigation of the low temperature spin dynamics in two well-characterized kagomé bilayer compounds SrCr9xGa12-9xO19 (x=0.95, SCGO) and Ba2Sn2ZnCr7xGa10-7xO22 (x=0.97, BSZCGO) reveals two novel features. One is the slowing down of the relaxation rate without critical behavior at Tg, where a macroscopic spin-glass-like freezing occurs. The second is, in SCGO at 4 K (approximately Tg)<T<7 K, the relaxation rate activation energy Ea=7+/-0.4 meV, equal to the energy of a phonon mode, pointing out the role of spin-lattice coupling.

Journal Article↗
PubMed2006

Superconductivity in a molecular metal cluster compound.

Compelling evidence for band-type conductivity and even bulk superconductivity below Tc approximately 8 K has been found in (69,71)Ga NMR experiments in crystalline ordered, giant Ga84 cluster compounds. This material appears to represent the first realization of a theoretical model proposed by Friedel in 1992 for superconductivity in ordered arrays of weakly coupled, identical metal nanoparticles.

Journal Article↗
PubMed2005

Ground state of the kagomé-like S=1/2 antiferromagnet volborthite Cu3V2O7(OH)2 x 2H2O.

The volborthite compound is one of the very few realizations of S=1/2 quantum spins on a highly frustrated kagomé-like lattice. Low-T SQUID measurements reveal a broad magnetic transition below 2 K which is further confirmed by a peak in the 51V nuclear spin relaxation rate (1/T1) at 1.4 K +/- 0.2 K. Through 51V NMR, the ground state (GS) appears to be a mixture of different spin configurations, among which 20% corresponds to a well defined short-range order, possibly of the sqrt(3) x sqrt(3) type. While the freezing involves all the Cu2+ spins, only 40% of the copper moment is actually frozen which suggests that quantum fluctuations strongly renormalize the GS.

Journal Article↗
PubMed2005

Cascade of bulk magnetic phase transitions in NaxCoO2 as studied by muon spin rotation.

Using muon spin rotation, well-defined bulk approximately 100% magnetic phases in NaxCoO2 are revealed. A novel magnetic phase is detected for x=0.85 with the highest transition temperature ever observed for x>or=0.75. This stresses the diversity of x>or=0.75 magnetic phases and the link between magnetic and structural degrees of freedom. For the charge-ordered x=0.50 compound, a cascade of transitions is observed below 85 K. From a detailed analysis of our data, we conclude that the ordered moment varies continuously with temperature and suggest that the two secondary transitions at 48 and 29 K correspond to a moderate reorientation of antiferromagnetically coupled moments.

Journal Article↗
PubMed2004

muSR study of the quantum dynamics in the frustrated S=3/2 kagomé bilayers.

We present muSR experiments in the S=3/2 kagomé bilayer compound Ba(2)Sn(2)ZnGa(10-7p)Cr(7p)O22 [BSZCGO(p)] and compare it to the isostructural SrCr(9p)Ga(12-9p)O19 [SCGO(p)], including for the latter new results for p > or =0.89. Quantum-dynamical low energy magnetic excitations are evidenced in this novel compound. We study the evolution of the muon relaxation rate with p, T, and field. A phenomenological model for the muon relaxation based on sporadic dynamics due to spin excitations in a singlet sea proposed by Uemura et al. is extended to all fields and T range. Its connection to the RVB picture is discussed, and we argue that such coherent states might mediate the interactions between "impurities" which induce the spin glass freezing.

Journal Article↗
PubMed2004

Intrinsic susceptibility and bond defects in the novel two dimensional frustrated antiferromagnet Ba2Sn2ZnCr7pGa10-7pO22.

We present microscopic and macroscopic magnetic properties of the highly frustrated antiferromagnet Ba(2)Sn(2)ZnCr(7p)Ga(10-7p)O22, respectively, probed with NMR and SQUID experiments. The T variation of the intrinsic susceptibility of the Cr3+ frustrated Kagomé bilayer, chi(Kag), displays a maximum around 45 K. The dilution of the magnetic lattice has been studied in detail for 0.29</=p</=0.97. Novel dilution independent defects, likely related with magnetic bond disorder, are evidenced and discussed. We compare our results to SrCr(9p)Ga(12-9p)O19. Both bond defects and spin vacancies do not affect the average susceptibility of the Kagomé bilayers.

Journal Article↗
PubMed2001

[Continuous brachial plexus blockade for shoulder surgery].

Continuous brachial plexus block is the technique of choice for postoperative shoulder pain treatment. The localization of the plexus is usually obtained drawing landmarks on the skin and using the electrical nerve stimulator; these and other different modalities are applied in order to reach safely and precisely nerve roots to be blocked with an anaesthetic solution. The Author presents a new anatomical perspective to guide the localization of the brachial plexus. It is shown how it is possible to detect the pathway of the brachial plexus from the cutaneous surface, linking between each other various landmarks: a) the apex of the scalene triangle, at the cross of a line leaving from the cricoid process and directed posterior to the posterior border of the sternocleidomastoid muscle, b) the midline of the clavicle c)the deltoid-pectoral sulcus d) the midpoint between the coracoid process and the chest profile e) the pulsation of the artery in the axylla. Following the guide of the so formed anesthetic line, is possible to place the needle, with a direction from distal to proximal, in a tangential route towards the interscalenic groove, thus allowing to perform a block of the plexus in a simple and efficacious way.

Brachial Plexus↗
PubMed2001

[Jejunostomy for enteral feeding in surgery. Technical contribution and experience].

UNLABELLED: The necessity to maintain the nutritional integrity in patients subjected to major surgery of the superior digestive tract has been broadly accepted. The enteral nutrition for yeyunostomy is accepted as more physiologic, sure and effective than the parenteral one. MATERIALS AND METHOD: 171 yeyunostomies were indicated in: 151 patients with malignant neoplasm of the superior digestive tract, 15 with infected pancreatic necrosis, 3 bile-duodenum-pancreatic traumatisms and in 1 stenosis for gastroesophagic reflux. Depending on the pathological type, a yeyunostomy using the Witzell technique was carried out with either local or general anesthesia at a 15 to 20 cm. of the Treitz angle. To facilitate the fixation of the catheter and to avoid the stenosis of the jejunum we have incorporated, as an original technical detail, the proximal serous section with cold scalpel in about 4 cm, that is to say in the sector to be tunneled. RESULTS: There was not mortality in relation to the yeyunostomy. Among the minor complications we emphasize the abdominal distension, colic pain and diarrhea, situations that were reverted, controlling the debit and the feeding characteristics. This approach could be maintained for period of 2 months and in some cases at home. CONCLUSIONS: We emphasize the great importance of the enteral feeding for yeyunostomy, for its of easy handling, security and low cost that, together with the suggested technical detail, has allowed us to obtain a deeding road almost without inherent complications.

Digestive System Surgical Procedures↗
PubMed1999

[Loco-regional block in ophthalmic surgery: single drug or drug combination with hyaluronidase? Randomized prospective study].

UNLABELLED: The aim of this study is the comparison between the use of bupivacaine alone and a mixture of bupivacaine, mepivacaine and hyaluronidase in both retrobulbar and peribulbar blockades for eye surgery. Three hundred ninety-nine consecutive adult patients scheduled for cataract surgery with regional anaesthesia were included in this prospective, randomized and partially blind study. Peribulbar blockade was performed on 199 patients (group P). Ninety-nine of them received a mixture of local anaesthetics and hyaluronidase (sub-group M), while 100 received bupivacaine alone (sub-group B). Retrobulbar blockade was performed on 200 patients (group R): 100 of them received the mixture with hyaluronidase (sub-group M), while 100 received bupivacaine (sub-group B). The interval between anaesthesia and motor blockade (onset time), the presence of residual ocular movements, the need of further anaesthesia, the quality of anaesthesia, the ocular tone, the length of anaesthesia and possible complications were registered. RESULTS: Retrobulbar blockade has the only advantage of a shorter onset time, while peribulbar blockade shows a longer anaesthetic effect. Mixture with hyaluronidase (the sub-group M) has a shorter onset time, a lesser need of further anaesthesia, fewer residual ocular movements and a better quality of anaesthesia. CONCLUSIONS: Local anaesthetics mixture with hyaluronidase associated with peribulbar blockade presents the advantages of rapidity, duration and better quality without the risks of retrobulbar blockade side effects.

Adult↗
PubMed1999

[Amplifying right colectomy: place in the treatment of obstructive proximal left colon cancer].

The results obtained about nineteen (19) patients operated by left colon cancer with variable grade obstruction have been analysed. Seventeen (17) patients operated due to obstructive left colon cancer situated: five (5) in distal transverse colon, other five (5) at splenic flexure and seven (7) in proximal descending colon but three of them with right synchronic neoplasias. The remaining two (2) that showed a cancer located at splenic flexure and the other one in proximal descending colon were reoperated three weeks later than a transverse colostomy had been performed owing to an obstructive condition. One patient had to be reoperated because a generalised peritonitis from a fistula with partial disruption on end to end ileo-colic anastomosis. Exteriorization of both ends was carried out with favourable evolution and subsequent reanastomosis. An exteriorized patient by splenic flexure cancer also had to be drained ten days later for a retroperitoneal abscess through a percutaneous puncture and a lesion grade 1 in lower pole of spleen was resolved with electrofulguration. No patient has showed invalidating diarrhea and all themselves have been stabilised with two or three stools daily about two month after surgery. Amplifying right colectomy is a safe procedure with low surgical morbimortality and take privileged place in the treatment of the patients undergoing synchronical neoplasias and/or carcinomas associated with polyps, specially in all those cases when a variable grade of obstruction have occurred.

Aged↗
PubMed1992

Effect of PEEP on respiratory mechanics in anesthetized paralyzed humans.

With the use of the technique of rapid airway occlusion during constant flow inflation, respiratory mechanics were studied in eight anesthetized paralyzed supine normal humans during zero (ZEEP) and positive end-expiratory pressure (PEEP) ventilation. PEEP increased the end-expiratory lung volume by 0.49 liter. The changes in transpulmonary and esophageal pressure after flow interruption were analyzed in terms of a seven-parameter "viscoelastic" model. This allowed assessment of static lung and chest wall elastance (Est,L and Est,W), partitioning of overall resistance into airway interrupter (Rint,L) and tissue resistances (delta RL and delta RW), and computation of lung and chest wall "viscoelastic constants." With increasing flow, Rint,L increased, whereas delta RL and delta RW decreased, as predicted by the model. Est,L, Est,W, and Rint,L decreased significantly with PEEP because of increased lung volume, whereas delta R and viscoelastic constants of lung and chest wall were independent of PEEP. The results indicate that PEEP caused a significant decrease in Rint,L, Est,L, and Est,W, whereas the dynamic tissue behavior, as reflected by delta RL and delta RW, did not change.

Abdominal Muscles↗
PubMed1992

[Urapidil and dopamine in severe heart failure. A clinical case].

The Authors report their experience with a new vasodilator drug (Urapidil) employed in the management of serious cardiac failure, in a patient who previously didn't respond in a satisfactory manner to a therapy with Dopamine alone. After several days of continuous treatment, the patient was discharged, without any sign of toxic or metabolic reactions.

Aged↗
PubMed1991

Electrical and mechanical output of the expiratory muscles in anesthetized dogs.

In anesthetized intact and vagotomized dogs chest wall diameters, expiratory muscles' (EM) electrical activity, work, mean pressure and volume displacement contributed by EM contraction were assessed in the supine and upright posture during rebreathing, and during continuous positive pressure breathing (CPAP) in the supine posture. Corresponding inspiratory mechanical output variables were related to diaphragm activity. During resting breathing triangularis sterni and internal interosseous were more easily recruited than transversus abdominis and external oblique. EM activity increased with tilting, CPAP and rebreathing. Vagotomy depressed or abolished abdominal EM activity, with lesser effects on rib cage EM. Expiratory mechanical output grossly paralleled EM activity: it markedly depended on rib cage and abdominal EM coactivation, besides lung inflation and chest wall shape. Upper rib cage configuration at end-expiration never departed from the relaxation one, suggesting trivial effects of the triangularis sterni contraction. Lower chest wall distortion occurred almost regularly, so that much of EM activity was not converted into external work. In contrast with expiratory electromechanical relations, those for the diaphragm were always highly significant and independent of EM activation.

Animals↗
PubMed1991

Pulmonary and chest wall mechanics in anesthetized paralyzed humans.

Pulmonary and chest wall mechanics were studied in 18 anesthetized paralyzed supine humans by use of the technique of rapid airway occlusion during constant-flow inflation. Analysis of the changes in transpulmonary pressure after flow interruption allowed partitioning of the overall resistance of the lung (RL) into two compartments, one (Rint,L) reflecting airway resistance and the other (delta RL) representing the viscoelastic properties of the pulmonary tissues. Similar analysis of the changes in esophageal pressure indicates that chest wall resistance (RW) was due entirely to the viscoelastic properties of the chest wall tissues (delta RW = RW). In line with previous measurements of airway resistance, Rint,L increased with increasing flow and decreased with increasing volume. The opposite was true for both delta RL and delta RW. This behavior was interpreted in terms of a viscoelastic model that allowed computation of the viscoelastic constants of the lung and chest wall. This model also accounts for frequency, volume, and flow dependence of elastance of the lung and chest wall. Static and dynamic elastances, as well as delta R, were higher for the lung than for the chest wall.

Adolescent↗