Polyethylene pipes exposed to chlorine dioxide in drinking water supply system: A critical review of degradation mechanisms and accelerated aging methods

Polyethylene (PE) pipes have been widely used in drinking water distribution systems across the world. In many cases, chlorine dioxide (ClO₂) is used to maintain a residual disinfectant concentration in potable water. Practical experiences have shown that the lifetime of PE pipes is significantly reduced due to exposure to drinking water with ClO₂. Recently, many companies have proposed new PE pipes with a modified formulation, which are more resistant to chlorine dioxide. However, a standardized test method for evaluating the long-term performances of PE pipes is still missing. This literature review was performed to provide a description of chlorine dioxide uses and degradation mechanisms of polyethylene pipes in real water distribution systems. Current accelerated aging methods to evaluate long-term performances of PE pipes exposed to ClO₂ are described and discussed along with the common technics used to characterize the specimens. Accelerate aging methods can be distinguished in immersion aging tests and pressurized pipe loop tests. Wide ranges of operational conditions (chlorine dioxide concentration, water pressure, water temperature, etc.) are applied, resulting in a great variety of results. It was concluded that pressurized looping tests applying semi-realistic operational conditions could better replicate the aging mechanisms occurring in service. Despite this, the acceleration and the evaluation of the long-term performance are still difficult to determine precisely. Further experimentation is needed to correlate chemical-mechanical characterization parameters of PE pipes with their lifetime in service.

A vibrational in vitro approach to evaluate the potential of monoolein nanoparticles as isofuranodiene carrier in MDA-MB 231 breast cancer cell line: New insights from Infrared and Raman microspectroscopies

Isofuranodiene (IFD) is a sesquiterpene occurring in several plant species, which proved to have multiple anticancer activities. IFD has a lipophilic nature and, hence, a very low water solubility and a poor bioavailability; moreover, it is not stable, undergoing the "Cope rearrangement" to the less active curzerene. The use of appropriate delivery systems can thus be considered as a valid tool to enhance IFD bioavailability, solubility, stability and at the same time also to improve its intracellular uptake and pharmacological activity. Within this frame, monoolein (GMO) nanoparticles loaded with IFD were prepared and their enhanced anticancer activity, compared to pristine IFD, was assessed. In this study, for the first time, an in vitro Fourier Transform Infrared and Raman Microspectroscopy approaches were exploited to evaluate the effects of IFD, alone and loaded in GMO nanoparticles, on MDA-MB 231 breast cancer cell line. The anti-cancer effects of IFD were evidenced by both the spectroscopic techniques and discriminated from the GMO-induced changes in the culture environment; moreover, a synergistic effect of IFD and GMO administration can be envisaged by the experimental results.

Transformation of industrial and organic waste into titanium doped activated carbon - cellulose nanocomposite for rapid removal of organic pollutants

Production of cost-efficient composite materials with desired physicochemical properties from low-cost waste material is much needed to meet the growing needs of the industrial sector. As a step forward, the current study reports for the first time an effective utilization of industrial metal (inorganic) waste as well as fall leaves (organic waste), to produce three types of nanomaterials at the same time; "Titanium Doped Activated Carbon Nanostructures (Ti-ACNs)", "Nanocellulose (NCel)", and combination of both "Titanium Doped Activated Carbon Cellulose Nanocomposite (Ti-AC-Cel-NC)". X-ray diffraction (XRD), transmission electron microscopy (TEM) and microanalysis (EDXS) measurements reveal that the Ti-ACNs material is formed by Ti-nanostructures, generally poorly crystalized but in some cases forming hexagonal Ti-crystallites of 15 nm, embedded in mutated graphene clouds. Micro- Fourier transform infrared spectroscopy (micro-FTIR) confirms that the chemical structure of NCel with bond vibrations between 1035 to 2917 cm^-1 remained preserved during Ti-AC-Cel-NC formation. The prepared materials (Ti-ACNs, Ti-AC-Cel-NC) have demonstrated rapid removal of organic pollutants (Crystal Violet, Methyl Violet) from wastewater through surface adsorption and photocatalysis. In the first 20 min, Ti-ACNs have adsorbed ≈87% of the organic pollutants and further photocatalyzed them up to ≈96%. When Ti-ACNs are combined with NCel, their efficiency is increased of about four times. This performance originates from the adsorption by mutated graphene-like carbon and assisted photocatalysis by Ti nanostructures as well as the good supporting capacity of NCel for the homogenous Ti-ACNs distribution.

Cubic and Hexagonal Mesophases for Protein Encapsulation: Structural Effects of Insulin Confinement

Monoolein-based cubic and hexagonal mesophases were investigated as matrices for insulin loading, at low pH, as a function of temperature and in the presence of increasing amounts of oleic acid, as a structural stabilizer for the hexagonal phase. Synchrotron small angle X-ray diffraction, rheological measurements, and attenuated total reflection-Fourier transform infrared spectroscopy were used to study the effects of insulin loading on the lipid mesophases and of the effect of protein confinement in the 2D- and 3D-lipid matrix water channels on its stability and unfolding behavior. We found that insulin encapsulation has only little effects both on the mesophase structures and on the viscoelastic properties of lipid systems, whereas protein confinement affects the response of the secondary structure of insulin to thermal changes in a different manner according to the specific mesophase: in the cubic structure, the unfolding toward an unordered structure is favored, while the prevalence of parallel β-sheets, and nuclei for fibril formation, is observed in hexagonal structures.

One-pot synthesis of alkyl pyrrole-2-carboxylates starting from β-nitroacrylates and primary amines

Herein, we present a new, efficient, one-pot synthesis of pyrrole-2-carboxylate derivatives starting from ketal-functionalized β-nitroacrylates in combination with primary amines under acidic heterogeneous conditions.

PEA I and PEA II based implantable haemodynamic monitor: pre clinical studies in sheep

AIMS

The aims of this study were first, to demonstrate that Peak Endocardial Acceleration during isovolumic systole (PEA I) is related to positive peak LVdP/dt, while Peak Endocardial Acceleration during isovolumic relaxation time (PEA II) is related to aortic diastolic pressure (ADP) and to negative peak LVdP/dt; and second, to test if the simultaneous recording of PEA I and PEA II offers a new chance to monitor indexes of LV systolic and diastolic function.

METHODS

An implantable haemodynamic monitor, based on PEA I and PEA II measurements via a microaccelerometer sensor located in the tip of a pacing lead, screwed into the right ventricle, was tested in nine sheep at baseline and during acute haemodynamic interventions: nitrate (0.1 mg/ kg), metaraminol (0.15 mg/kg), dobutamine (5 microg/kg) infusion. ADP, positive and negative peak LVdP/dt were simultaneously recorded by an aortic and left ventricular Millar catheter.

RESULTS

PEA I changes were significantly related to positive peak LVdP/dt changes during dobutamine induced inotropic changes (r = 0.83, P < 0.001). PEA II changes were significantly related to both ADP (r = 0.91, P < 0.001) and negative peak LVdP/dt changes (r = 0.92, P < 0.001) during nitrate induced hypotension and metaraminol induced hypertension.

CONCLUSION

The simultaneous recording of PEA I and PEA II with an implantable system offers a new chance to monitor indexes of LV systolic and diastolic function.

Peak endocardial acceleration reflects heart contractility also in atrial fibrillation

Previous studies demonstrated that peak endocardial acceleration (PEA) in sinus rhythm is related to LV dP/dtmax. Until now, PEA was never evaluated during R-R interval variations in AF. The aim of this study was to establish the behavior of PEA in AF and the relationship of PEA versus LV dP/dtmax. Six sheep (65 +/- 6 kg) were instrumented with a LV Millar catheter and with an accelerometer lead. AF was induced and PEA, LV dP/dtmax, and ECG were monitored. AF persisted for 5 +/- 1.3 minutes. From sinus rhythm to AF, the heart rate went from 92 +/- 3 to 130 +/- 35 beats/min (P < 0.05), LV dP/dtmax from 684 +/- 18 to 956 +/- 344 mmHg/s (P = NS) and PEA from 0.82 +/- 0.06 to 0.94 +/- 0.33 g (P = NS). The correlation between PEA and LV dP/dtmax was significative in sinus rhythm (r = 0.7, P < 0.05) and in AF (r = 0.8, P < 0.05). A positive relationship was found between the preceding interval and PEA (r = 0.4 +/- 0.07, P < 0.05) and LV dP/dtmax (r = 0.61 +/- 0.08, P < 0.05), while a negative one was found between the prepreceding interval and both PEA (r = -0.39 +/- 0.11, P < 0.05) and LV dP/dtmax (r = -0.64 +/- 0.05, P < 0.05). At the onset of AF, LV dP/dtmax and PEA showed similar changes: beat-to-beat correlation between PEA and LV dP/dtmax was high. As for LV dP/dtmax, PEA is positively related to the preceding interval and negatively related to the prepreceding interval. These data confirm that PEA reflects heart contractility also during AF and hold promise for the use of this sensor in therapeutic implantable devices.

Primary endoleakage in endovascular treatment of the thoracic aorta: importance of intraoperative transesophageal echocardiography

OBJECTIVES

Endovascular treatment of the thoracic aorta has developed as an efficacious alternative to open surgical repair. However, despite the high primary success rate, perigraft leakage constitutes the major concern in long-term follow-up. Endoleaks are widely reported both in abdominal and thoracic endovascular series and are usually identified by intraoperative angiography. Transesophageal echocardiography is a sensitive imaging technique in the evaluation of aortic diseases, widely used to monitor cardiac surgery. The aim of this study was to evaluate the efficacy of transesophageal echocardiography in leakage detection during endovascular stent procedures of the thoracic aorta.

METHODS

Intraoperative transesophageal echocardiography was used in conjunction with angiography in 25 patients subjected to endovascular stent treatment of the descending thoracic aorta. Spiral computed tomographic scanning was performed before discharge and 3, 6, and 12 months after treatment.

RESULTS

Information from transesophageal echocardiography was relevant in the selection of the landing zone in 62% of cases. In 8 patients, transesophageal echocardiography with color Doppler sonography showed a perigraft leak, 6 of which were not visible on angiography, suggesting the need for further balloon expansion or graft extension. Postoperative computed tomographic scanning in the 25 patients showed 1 endoleak, which sealed spontaneously. At 3 months, computed tomographic examination confirmed the absence of perigraft leakage in all patients.

CONCLUSIONS

During implantation of a stent-graft in the descending thoracic aorta, transesophageal echocardiography provides information in addition to that provided by angiography, improving immediate and late procedural results.

[Endovascular treatment in diseases of the thoracic aorta]

PURPOSE

To determine whether endovascular treatment of thoracic aorta conditions can be an effective alternative approach to surgical repair.

MATERIAL AND METHODS

July 1997 to February 1999, eighteen patients (16 men and 2 women; 58.6 +/- 14.8 years) presenting with different kinds of descending aorta conditions were selected for the endovascular treatment. All patients exhibited severe comorbid pulmonary and/or cardiovascular medical conditions which increased surgical risk. All implants were performed in the operating room under fluoroscopic and TEE guidance. Clinical and imaging follow-up was performed 1, 3, 6 and 12 months later.

RESULTS

The endovascular treatment was successful in 17 cases. No deaths or major complications occurred. No leakage was evident at post-procedure angiography. The patients were discharged after 6 +/- 4 days. MRI or CT study performed before hospital discharge showed aneurysms exclusion in 16 patients. In the four cases of dissection, thrombosis of the false lumen was evident since the first follow-up study. In the group of patients (11 cases) with 6 months follow-up, the diameters of stented aortic segments decreased. No late leakage was observed and thrombosis was complete in all cases.

DISCUSSION

The natural history of aortic aneurysms and dissection is progressive toward dilation and aortic rupture. Surgery of descending thoracic aorta is burdened with a mortality of 8-12% in elective cases and over 50% in emergency cases or aortic dissection. The endovascular treatment of aortic conditions was introduced in clinical practice in 1991 and literature data show that it is effective, with lower mortality and morbidity rates than surgical treatment.

CONCLUSION

Our results stress the feasibility and effectiveness of endovascular procedure in the treatment of complex thoracic aorta conditions even in high risk patients. Thus, endovascular treatment of thoracic aorta can be considered an effective alternative approach to conventional surgery.

Cardioverter-defibrillator oversensing due to double counting of ventricular tachycardia electrograms

We report a case of a patient with idiopathic dilated cardiomyopathy and recurrent ventricular tachycardias refractory to antiarrhythmic treatment with amiodarone. A cardioverter defibrillator implantation was performed by the transvenous technique, but ventricular tachycardia detection resulted to be inappropriate because of constant double sensing of ventricular tachycardia electrograms (QRS width=250 ms). Device programmability didn't allow a satisfactory solution to this problem, therefore a more appropriate sensing system was considered. Through an anterior thoracotomy two epicardial wires were positioned and sensing by these wires, placed closer to ventricular tachycardia origin, resulted appropriate. An electrophysiologic study and subsequent follow up confirmed appropriate ICD detection of ventricular tachycardias. This case emphasizes how in some cases sensing by epicardial wires may be a solution for QRS double counting occurring with endocardial leads during ventricular tachycardia.

[Transvenous cardioverter-defibrillators: clinical experience at implantation and follow-up]

Thirty-seven patients with ventricular tachyarrhythmias refractory to antiarrhythmic drug treatment, guided by electrophysiological testing, were submitted to implantation of a cardioverter-defibrillator by the transvenous technique. Mean age was 55 +/- 14 years and the underlying heart disease was coronary heart disease in 24 patients, cardiomyopathy or other etiologies in 11 patients. In 2 patients ventricular arrhythmias were idiopathic. Left ventricular ejection fraction was < or equal to 40% in 65% of the patients. The following devices were implanted: CPI Ventak P in 2 patients, Ventak P2 in 9 patients, Ventak PRx in 9 patients, Ventak PRxII in 2 patients, Telectronics Guardian ATP III 4215 in 9 patients, Siemens Siecure in 5 patients, Medtronic Jewel PCD in 1 patient. At implantation defibrillation threshold was lower with biphasic shocks than with monophasic shocks (17.0 +/- 3.2 vs 20.9 +/- 3.8 J, p < 0.003) and the need for subcutaneous patches was lower when biphasic shocks were employed. Operative and perioperative mortality were 0% and no significant complications were observed. During the follow-up (16 +/- 11 months) 35% of the patients had appropriate shocks and 93% of the patients with antitachycardia pacing availability (n = 15) had effective antitachycardia pacing interventions. The following complications were observed: lead failure in 4 patients (3 insulation breaks and 1 elongation for stretching), late lead dislodgement in 2 patients, lead recall in 1 patient, all of which required reintervention. Inappropriate shocks occurred in 30% of the patients and were related to lead failure, supraventricular arrhythmias or alternating current interference. During the follow-up one patient died of sudden death and one was submitted to heart transplantation. In conclusion, implantation of a cardioverter-defibrillator by the transvenous technique is a procedure relatively free from complications. During the follow-up lead failure appears to be one of the most relevant complications. Antitachycardia pacing allows effective termination of ventricular tachycardias without cardioversion, with a better compliance.

[Neoplastic caval and intracardiac thrombosis secondary to reno-adrenal tumors. One-stage surgical treatment in deep hypothermia and cardiocirculatory arrest]

Due to the considerable progress made by instrumental total body diagnostics (ECO, CAT, RMN, angiography, etc.) in recent years heart surgery has increasingly often been used to treat pathologies which are not primarily cardiac but which see the involvement of the heart and large vessels in the advanced stages of cancer and non-cancer diseases of other organs or apparatus. This is the case of malignant renal or adrenal tumours which infiltrate along the caval lumen until they reach the right atrium. In these cases caval and atrial involvement must be seen as a prolapse of the tumour and not a long-distance metastasis: prognosis only appears to be linked to the hemodynamic impairment caused by the obstacle to systemic lower venous drainage. On the bases of this observation radical surgery may be justified at a renal, caval and cardiac level. The authors report their preliminary experience in 6 patients with renal cancer (4 renal carcinoma, 1 Wilm's tumour, 1 adrenal carcinoma) who underwent combined surgery, in a single stage, involving enlarged nephrectomny and caval and atrial thrombectomy, the latter performed in profound hypothermia and cardiocirculatory arrest. Two patients died later and 4 are living, in good condition and with perviousness of the lower caval venous drainage. Similar to other analogous experience reported in the literature, the authors suggest taking a combined approach performed in a single stage into consideration for these patients.

Multicenter clinical evaluation of a new SSIR pacemaker

A multicenter clinical evaluation of Sorin Swing 100, a new SSIR pacemaker with a gravimetric sensor, was performed by seven different centers enrolling a total of 89 patients, 56 men and 33 women, mean age 73.1 years, for pacemaker implantation (73 patients) or pacemaker replacement (16 patients). Pacing mode was VVIR in 73 patients and AAIR in 16. The behavior of pacing rate was evaluated 3 months after the implant by performing a 24-hour Holter monitor, an exercise stress test, and tests for the assessment of mechanical external interference (MEI). A physiological behavior of the paced rate was always observed during Holter monitoring. In 52 completely paced patients mean diurnal, nocturnal, and maximal heart rate were, respectively, 74.9 +/- 5.7 ppm, 58.1 +/- 5.8 ppm, and 113.4 +/- 12.7 ppm; a paced rate exceeding 100 ppm was reached on the average 5.6 times/Holter monitor. In all but two patients the sleep rate (55 ppm) was reached during the night or long resting time. During exercise stress test a direct correlation between the increase in pacing rate and the increase in workload was observed; the mean maximal heart rate reached in 49 completely paced patients was, respectively, 102.8 +/- 9 ppm in 17 patients who accomplished stage 1, 116.2 +/- 13.6 ppm in 28 patients who accomplished stage 2, and 133 +/- 6.7 ppm in 10 patients who accomplished stage 3 of the Bruce protocol. MEI testing never increased the pacing rate over the noise rate (10 ppm over the basic rate). In only seven patients the results obtained suggested to change the nominal set up of the pacemaker.(ABSTRACT TRUNCATED AT 250 WORDS)