Series and parallel coupling of 3D printed micro-perforated panels and coiled quarter wavelength tubes.

Micro-perforated panel sound absorbers are widely used in noise control applications in the fields of architectural acoustics and transport acoustics. Combining micro-perforated panels with other resonant or sound absorbing systems may broaden the frequency range in which they absorb sound while ensuring that large sound absorption values are reached. In this work, a hybrid sound absorber that combines a micro-perforated panel and a coiled quarter wavelength tube is proposed. Series and parallel configurations of these two systems are studied from analytical, numerical, and experimental point of views. A comparison of two three-dimensional (3D) printing techniques for the production of samples highlights the main challenges for the practical implementation of the proposed design. The advantages and limitations of series and parallel arrangements are discussed and while the parallel configuration is more complex to setup in practice, it provides an improved sound-absorbing performance compared with the series configuration. Finally, the reproducibility of the hybrid absorber in parallel configuration is confirmed by testing samples that were produced with two different 3D printers and in two different laboratories.

Experimental pseudo-equivalent deterministic excitation method extension for low frequency domain applications.

In transport engineering applications, flow-induced vibrations is an interesting topic to address since it may negatively affect the operation and the response of the system. Wind tunnel facilities are mandatory to test the structure design efficiency or to analyse new material performances under aerodynamic load. However, these experimental tests can be expensive and take a long time to set up and operate; hence, alternative methods for the reproduction of the structural response to a turbulent boundary layer excitation are required to accelerate and improve the experimental setups and provide more data for uncertainty analysis. In this paper, an alternative approach, the eXperimental Pseudo-Equivalent Deterministic Excitation method (X-PEDEM), is here extended for applications in the low frequency domain. An investigation about the applicability of the method in the low frequency domain is conducted, together with an analysis of its main properties. The reliability of the method is then tested numerically by considering different conditions: two different panels, two different boundary conditions, and different asymptotic flow velocities are considered.

Early Results of Rheumatic Mitral Valve Repair.

BACKGROUND AND AIM OF THE STUDY: Mitral valve repair (MVr) in rheumatic heart disease (RHD) remains challenging. The present authors' surgical experience of MVr in 56 patients with RHD operated in between January 2011 and September 2014 is reported. METHODS: Among the patients (mean age 32 ± 11 years), 11 were in NYHA functional class II, 32 in class III, and seven in class IV. An adequate or oversized autologous pericardial patch was sutured to extend the coaptating edge of both the anterior leaflet (in 18 patients) and the posterior leaflet (in 30 patients). Neochordae were implanted as needed (n = 43), and leaflet thinning (n = 13), commissurotomy (n = 15) and chordal splitting (n = 9) were also performed. A rigid annuloplasty ring was implanted in 32 patients, and in 24 patients a complete flexible annuloplasty ring made from pericardium, 4 mm Gore-Tex tube graft or a Dacron patch was constructed. Repair was not attempted in 16 patients, with replacement using a mechanical bileaflet prosthesis being considered the only option. RESULTS: Intraoperative post-repair transesophageal echocardiography demonstrated competency, with trivial mitral regurgitation (MR) up to grade I in all patients and a minimum coaptation depth ≥5 mm. There were no intraoperative or in-hospital deaths. Clinical and echocardiographic evaluations were performed up to six weeks after surgery, at which time 51 patients were in NYHA classes I-II and five were in class III. Residual mild MR up to grade I was identified in six patients. No recurrence of MR was observed in any of the patients, and no patients were reoperated on. CONCLUSIONS: The lack of adequate access to anticoagulation medication and monitoring, in addition to religious/cultural bias to the type of prosthetic valve used in low-income countries, necessitates an increase in the numbers of rheumatic MVr.

Effects of Surgical Techniques on Long-Term Results in Patients with Degenerative Mitral Valve Bileaflet Prolapse.

BACKGROUND AND AIM OF THE STUDY: The study aim was to evaluate the long-term results in patients with degenerative mitral valve bileaflet prolapse (DMVBLP) undergoing mitral valve repair (MVr) or mitral valve replacement (MVR), and to compare the consequences of survival related to each technique. METHODS: Between 2001 and 2012, a total of 421 patients underwent isolated primary surgery for DMVBLP. MVr was performed in 146 patients (34.7%), and MVR in 275 (65.3%). MVR patients were allocated to two subgroups. Subgroup A were operated on in routine fashion, preserving the posterior subvalvular apparatus, and in selected cases the anterior or both apparatus (n = 119; 43.3%). In subgroup B, surgery was performed without preservation of the subvalvular apparatus (n = 156; 56.7%). RESULTS: There were no intraoperative deaths in all patient groups. The median length of follow up was 5.96 ± 3.28 years. Five patients (3.4%) in the MVr group died, while 11 in MVR subgroup A (9.2%) died, and 29 in MVR subgroup B (18.6%). Patients in the MVr group demonstrated significant and persistent postoperative decreases in left ventricular end-diastolic diameter (LVEDD) and left ventricular end-systolic diameter (LVESD) during the follow up, while the left ventricular ejection fraction (LVEF) showed a trend to improve. In MVR subgroup A, preservation of the mitral subvalvular structures resulted in a decrease in LVEDD; this resulted in a lesser worsening of the LVEF, as occurs when subvalvular structures are resected. In MVR subgroup B, the LVEDD and LVESD were each increased constantly, which resulted in a statistically significant worsening of the LVEF. CONCLUSIONS: MVr in DMVBLP patients achieved a better preservation of left ventricular systolic indices than MVR, and guaranteed better shortand long-term survivals. When MVr is not feasible, it is recommended that subvalvular preservation be performed during MVR, in order to reduce the risk of early and late mortality and to improve left ventricular function.

Monocentric case-series of mesenteric vascular disease occurred in the first month of the COVID-19 pandemic.

Objectives: we describe Coronavirus Disease (COVID-19) patients also manifesting gastro-intestinal symptoms. Methods: five women, between the ages of 32 and 82 years old, were admitted for acute abdomen, and received a nasopharyngeal swab for COVID-19 screening, lab test analysis, and contrast thoraco-abdominal CT-scan. All presented leukocytosis, different localizations of visceral vessels thrombosis and ischemia, and COVID-19. Results: emergency laparotomy was accepted by all but 1, who died after 5 days. Postoperatively, 1 died of multi-organ failure, 3 were discharged home after 14, 8 and 10 days respectively, under anti-platelet and anticoagulation treatment. Conclusions: in COVID-19 patients with acute abdomen, abdominal contrast CT-scans should be systematically extended to the thorax to detect visceral COVID-19 initial pulmonary signs. Emergency laparotomy and visceral arteries thrombectomy could be necessary.

Non Monotonous Effects of Noncovalently Functionalized Graphene Addition on the Structure and Sound Absorption Properties of Polyvinylpyrrolidone (1300 kDa) Electrospun Mats.

Graphene is an attractive component for high-performance stimuli-responsive or 'smart' materials, shape memory materials, photomechanical actuators, piezoelectric materials and flexible strain sensors. Nanocomposite fibres were produced by electrospinning high molecular weight Polyvinylpyrrolidone (PVP-1300 kDa) in the presence of noncovalently functionalised graphene obtained through tip sonication of graphite alcoholic suspensions in the presence of PVP (10 kDa). Bending instability of electrospun jet appears to progressively increase at low graphene concentrations with the result of greater fibre stretching that leads to lower fibre diameter and possibly conformational changes of PVP. Further increase of graphene content seams having the opposite effect leading to greater fibre diameter and Raman spectra similar to the pure PVP electrospun mats. All this has been interpreted on the basis of currently accepted model for bending instability of electrospun jets. The graphene addition does not lower the very high sound absorption coefficient, α, close to unity, of the electrospun PVP mats in the frequency range 200⁻800 Hz. The graphene addition affects, in a non-monotonous manner, the bell shaped curves of α versus frequency curves becoming sharper and moving to higher frequency at the lower graphene addition. The opposite is observed when the graphene content is further increased.

Three Cases of Aneurysmatic Coronary Fistulas Associated With Mitral Valve Insufficiency.

We report three cases of coronary fistula aneurysm associated with mitral valve insufficiency. The patients were referred to our cardiovascular department because of exertional dyspnea. Echocardiography showed severe mitral valve insufficiency resulting from leaflet flail or prolapse and normal left ventricular function. In all three cases, preoperative coronary angiography showed coronary-to-pulmonary artery fistula associated with significant aneurysm of the fistulous tract. All patients underwent uneventful mitral valve repair and external ligation of the fistulas.

Cerebral perfusion issues in acute type A aortic dissection without preoperative malperfusion: how do surgical factors affect outcomes?

OBJECTIVES: Both preoperative (disease-related) and operative (management-related) variables make the assessment of the outcomes of acute type A aortic dissection (ATAAD) surgery a difficult task. Our aim was to evaluate the impact of operative factors, including arterial cannulation site, route of cerebral perfusion and surgeon's specific experience with ATAAD ('aortic surgeon'), on the early results of surgical management, with particular attention to neurological injury. METHODS: Penn classification was used to identify clinically homogeneous risk groups of ATAAD patients undergoing surgery. Between January 2007 and June 2014, 111 of 183 ATAAD patients treated with open surgery in a single centre were in Penn Class Aa (no ischaemic complications at presentation). They were divided in two groups depending on the arterial cannulation site: femoral artery (FemA; 56 patients) or right axillary artery (RAxA; 55 patients). Study outcomes included: 30-day mortality, major adverse cardiac and cerebrovascular events at 30 days, neurological complications and in particular, patterns of stroke as defined by Bamford classification. RESULTS: No significant differences in preoperative variables were observed between cannulation-site groups, except for myocardial ischaemic time (60.9 ± 30.4 min in the RAxA group vs 81.7 ± 52.3 in the FemA group, P = 0.014) and cerebral perfusion time (42.1 ± 25.5 min in the RAxA group vs 52.9 ± 32.6 in the FemA group, P = 0.048). Outcomes in terms of mortality and neurological injury did not differ except for a higher incidence of lacunar cerebral infarction (LACI) in the RAxA group (14.5 vs 3.6%, P = 0.043), mainly but not exclusively explained by a higher incidence of LACI in unilateral (17.2%) than in bilateral cerebral perfusion (6.9%) within the RAxA group. The 'non-aortic surgeon' was associated instead with 30-day mortality and composite outcome in multivariable analysis (respectively, OR 6.40, P = 0.002 and OR 4.68, P = 0.001). CONCLUSIONS: The RAxA cannulation and FemA cannulation are associated with comparable 30-day mortality following surgery for aortic dissection. However, the possible higher risk of LACI-type strokes in the RAxA group, especially when associated with unilateral brain perfusion, should be considered when RAxA cannulation is performed in ATAAD. The hypothesis that more experienced surgeons may produce better earlier outcomes warrants further investigation.

4-Amino-3(2H)-pyridazinones bearing arylpiperazinylalkyl groups and related compounds: synthesis and antinociceptive activity.

A series of 4-amino-3(2H)-pyridazinones substituted at position 2 with arylpiperazinylalkyl groups and analogues were synthesized and their antinociceptive effect was evaluated in the mouse abdominal constriction model. Preliminary SARs studies were performed. Several of the novel compounds dosed at 100 mg/kg s.c. significantly reduced the number of writhes induced by the noxious stimulus. Compound 12e showed 100% inhibition of writhes and was able to protect all the treated animals from the effect of the chemical stimulus. Subsequent dose-response studies revealed 12e to be almost 40-fold more potent than the structurally related Emorfazone.

Anatomic reconstruction in degenerative mitral valve bileaflet prolapse: long-term results.

BACKGROUND: Degenerative mitral valve (MV) bileaflet prolapse (DMVBP) is recognized as one of the most complex lesions to be treated by reconstructive surgery. In the present study, we report our long-term results with reconstructive surgery for DMVBP. METHODS: From 2000 to 2011, 140 patients with MV regurgitation due to DMVBP were treated at our institution. Mean age was 56.4±14.5 years (range 16 to 84). Of the 140 study patients, 24 (17%) were in functional class I, 48 (34%) in class II, 60 (43%) in III, and 8 (6%) in class IV of the New York Heart Association. The MV leaflets were reconstructed without using prosthetic material, maintaining the normal shape and dimension of the valve ring and inter-papillary distance. The standard surgical procedure included the excision of the most elongated or ruptured chordae area of the posterior leaflet, with subsequent transposition of second-order chordae from the posterior leaflet to the most elongated or ruptured chordae area of the anterior leaflet. This procedure was performed in 123 patients. A para-commissural edge-to-edge was performed in 16 patients and a triangular resection of the anterior MV leaflet in 1 patient. The posterior leaflet was reconstructed with different techniques: a longitudinal suture of the annulus and residual scallops in 86 patients, a Z-plasty suture in 51 and a sliding suture of the residual posterior scallops in 3 patients. A posterior trygon-to-trygon annuloplasty was performed with an autologous pericardium strip in all patients. During follow-up, serial echocardiograms were obtained once a year. RESULTS: There were no hospital deaths. Mean follow-up was 6.42±3.1 years. Of the 140 study patients, 7 developed severe (3+), 10 moderate (2+) and 18 mild (1+) MV regurgitation. Two patients were reoperated within 6 months; 1 after 8 years and 1 after 10 years for recurrence of severe MV regurgitation. At 12 years after the initial surgical procedure, overall survival was 95.8%, freedom from MV re-intervention was 91.8% and freedom from late recurrence of 2+ or greater MV regurgitation was 78.7%. All patients had a satisfactory residual MV area, leaflets motion, and inter-papillary muscle distance. No patient developed left ventricular outflow tract obstruction. CONCLUSIONS: Our results confirm the effectiveness of anatomic reconstruction in the DMVBP. Survival rate after mitral valve repair is identical to that of the general population when surgery is performed in asymptomatic or pauci-symptomatic patients; the identification of this kind of patient is required followed by a therapeutic strategy for early surgery. This management approach in patients with DMVBP leads to optimal long-term results of MV repair.

Towards an individualized approach to bicuspid aortopathy: different valve types have unique determinants of aortic dilatation.

OBJECTIVES: Bicuspid aortic valve (BAV)-related aortopathy is increasingly recognized to be a heterogeneous disease entity, although the surgical approach, from indications to techniques, is still standard rather than individualized. We aimed to define the determinants of aortic dilatation in BAV patients stratified according to the valve morphotype. METHODS: A consecutive echocardiographic series of 622 BAV patients was analysed. Among demographic (age, sex), anthropometric (height, weight, body surface area, body mass index), clinical (associated diseases) and echocardiographic variables (valve function, ventricular parameters), the determinants of aortic root and ascending tract diameter were assessed by multivariate regression models, as well as the predictors of aortic dilatation (size index >2.1 cm/m(2)) both in the overall population and separately in groups of different valve morphotypes (RL, right-left fusion; RN, right-non-coronary fusion). RESULTS: Independent determinants of aortic root diameter (at sinuses) were age (P < 0.001), significant aortic regurgitation (P < 0.001), sex (female protective, P < 0.001) and valve morphotype (RN protective, P < 0.001). Independent determinants of ascending aortic diameter (tubular tract) were age (P < 0.001), RN morphotype (P < 0.001), body mass index (P = 0.005) and chronic obstructive pulmonary disease (P < 0.001). In univariate analysis, the RL morphotype was associated with dilatation (ASI > 2.1 cm/m(2)) at sinuses in 41% cases vs 22% for RN (P < 0.001), and the RN morphotype was associated with dilatation at the tubular tract in 68 vs 56% for RL (P = 0.007). The presence of root dilatation was predicted by age and absence of significant stenosis in the RL morphotype subgroup, and by severe regurgitation in the RN subgroup. In the RL-type subgroup, non-regurgitant aortic valve and chronic lung disease predicted dilatation at the ascending level; and in the RN-type subgroup, age and obesity. CONCLUSIONS: The two most common BAV morphotypes are associated with aortic dilatation at two different tracts (RL at the root; RN at the tubular ascending tract) independently of valve function. Moreover, the determinants of aortic dilatation were at least in part different between the two morphotypes: this may provide stratification criteria for individualized methods of follow-up and treatment.

Modification of nociception and morphine tolerance by the selective opiate receptor-like orphan receptor antagonist (-)-cis-1-methyl-7-[[4-(2,6-dichlorophenyl)piperidin-1-yl]methyl]-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ol (SB-612111).

(-)-cis-1-Methyl-7-[[4-(2,6-dichlorophenyl)piperidin-1-yl]methyl]-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ol (SB-612111) is a novel human opiate receptor-like orphan receptor (ORL-1) antagonist that has high affinity for the clonal human ORL-1 receptor (hORL-1 K(i) = 0.33 nM), selectivity versus mu-(174-fold), delta-(6391-fold), and kappa (486-fold)-opioid receptors and is able to inhibit nociceptin signaling via hORL-1 in a whole cell gene reporter assay. SB-612111 has no measurable antinociceptive effects in vivo in the mouse hot-plate test after intravenous administration but is able to antagonize the antimorphine action of nociceptin [ED(50) = 0.69 mg/kg, 95% confidence limit (CL) = 0.34-1.21]. SB-62111 administration can also reverse tolerance to morphine in this model, established via repeated morphine administration. In addition, intravenous SB-612111 can antagonize nociceptin-induced thermal hyperalgesia in a dose-dependent manner (ED(50) = 0.62 mg/kg i.v., 95% CL = 0.22-1.89) and is effective per se at reversing thermal hyperalgesia in the rat carrageenan inflammatory pain model. These data show that an ORL-1 receptor antagonist may be a useful adjunct to chronic pain therapy with opioids and can be used to treat conditions in which thermal hyperalgesia is a significant component of the pain response.

Evidence for a selective role of the delta-opioid agonist [8R-(4bS*,8aalpha,8abeta, 12bbeta)]7,10-Dimethyl-1-methoxy-11-(2-methylpropyl)oxycarbonyl 5,6,7,8,12,12b-hexahydro-(9H)-4,8-methanobenzofuro[3,2-e]pyrrolo[2,3-g]isoquinoline hydrochloride (SB-235863) in blocking hyperalgesia associated with inflammatory and neuropathic pain responses.

The specific involvement of the delta-opioid receptor in the control of nociception was explored by investigating the pharmacological activity in vivo of a selective, orally active, and centrally penetrant delta-opioid agonist. [8R-(4bS*,8aalpha,8abeta,12bbeta)]7,10-dimethyl-1-methoxy-11-(2-methylpropyl)oxycarbonyl 5,6,7,8,12,12b-hexahydro-(9H)-4,8-methanobenzofuro[3,2-e]pyrrolo[2,3-g]isoquinoline hydrochloride (SB-235863) is a new pyrrolomorphinan with high affinity (Ki = 4.81 +/- 0.39 nM) for the delta-opioid receptor, full agonist activity, and binding selectivity versus the mu- and kappa-opioid receptors of 189-fold and 52-fold, respectively. Perorally administered SB-236863 was inactive in the rat tail-flick and hot-plate tests of acute pain response, but potently reversed thermal hyperalgesia in rats resulting from a carrageenan-induced inflammatory response. This activity could be blocked by the delta-opioid antagonist naltrindole (3 mg/kg s.c.), but selective mu- and kappa-opioid antagonists were ineffective. Naltrindole (1 microg i.c.v.) also blocked the activity of 10 mg/kg (p.o.) SB-235863, showing that the compound activates delta-opioid receptor sites in the central nervous system. SB-235863 was additionally effective at reversing chronic hyperalgesia in the Seltzer rat model of partial sciatic nerve ligation after peroral administration. These data show that the delta-opioid receptor plays a selective role in regulating evoked and lasting changes in nociceptive pain signaling. Classical side effects of mu- and kappa-opioid receptor activation (slowing of gastrointestinal transit and motor incoordination, respectively) were not observed after administration of 70 mg/kg (p.o.) SB-235863, nor was evoked seizure activity affected. These results suggest a selective and limited role of delta-opioid receptors in the modulation of nociception.