Beyond waste: new sustainable fillers from fly ashes stabilization, obtained by low cost raw materials

A sustainable economy can be achieved only by assessing processes finalized to optimize the use of resources. Waste can be a relevant source of energy thanks to energy-from-waste processes. Concerns regarding the toxic fly ashes can be solved by transforming them into resource as recycled materials. The commitment to recycle is driven by the need to conserve natural resources, reduce imports of raw materials, save landfill space and reduce pollution. A new method to stabilize fly ash from Municipal Solid Waste Incinerator (MSWI) at room temperature has been developed thanks to COSMOS-RICE LIFE+ project (www.cosmos-rice.csmt.eu). This process is based on a chemical reaction that occurs properly mixing three waste fly ashes with rice husk ash, an agricultural by-product. COSMOS inert can replace critical raw materials (i.e. silica, fluorspar, clays, bentonite, antimony and alumina) as filler. Moreover the materials employed in the stabilization procedure may be not available in all areas. This paper investigates the possibility of substituting silica fume with corresponding condensed silica fume and to substitute flue-gas desulfurization (FGD) residues with low-cost calcium hydroxide powder. The removal of coal fly ash was also considered. The results will be presented and a possible substitution of the materials to stabilize fly ash will be discussed.

Suprarenal aortic cross-clamping in elective abdominal aortic aneurysm surgery

INTRODUCTION

this retrospective study was undertaken to evaluate whether suprarenal aortic cross-clamping increased the perioperative mortality and morbidity as compared to infrarenal clamping, in order to create the rationale for a more extensive application of this apparently more traumatic manoeuvre.

MATERIALS AND METHODS

in a series of 734 elective aortic substitutions for abdominal aneurysm (AA), performed consecutively from January 1992 to June 1999, aortic cross-clamping was performed at a suprarenal level in 56 juxtarenal aneurysms, i.e. aneurysms extending to the lower edge of the renal arteries (8%, Group 1), and at an infrarenal level in 634 subrenal aneurysms (92%, Group 2). When analysing preoperative data, the diameter of aneurysms was larger in Group 1 than in Group 2 (p<0. 005). No significant differences were found between the two groups as regards age, sex, postinfarction cardiomyopathy, chronic obstructive pulmonary disease, chronic renal insufficiency and ASA classification of operative risks.

RESULTS

the average time of renal exclusion in the juxtarenal aneurysms was 20 min (range 12-35 min). There is no difference between the two groups as regards the time of aortic clamping (mean 50 vs. 60 min) or the need for homologous blood transfusion (7% vs. 11% of patients). Perioperative (30 days) mortality did not differ: 3.6% vs. 1.9% (n.s.); nor did the incidence of acute myocardial infarction (3.6% vs. 2.3%). Renal function deteriorated in 8 (14%) vs. 0 (0%) (p<0.001) and 1 patient (2%) required permanent dialysis, as compared to 0% in Group 2. The incidence of ischaemic colitis was also significantly higher in Group 1 (7%) than in Group 2 (2%, p<0.01).

CONCLUSION

this data shows that suprarenal clamping, which is necessary for the radical treatment of juxtarenal aortic aneurysms, can be performed with a low risk.

[Carotid endarterectomy in patients with neurological non-side related (NSRS) symptoms]

Out of 970 carotid endarterectomies (CE) performed for high-grade (> 80%) stenosis of the internal carotid artery (ICA) until 1995, 147 patients with neurological non side-related symptoms (NSRS) and without any cardiac, ocular or vestibular significant pathology have been evaluated, analyzing the medium and long-term functional results (mean follow-up 37.6 months) related to the morphological status of the ICA contralateral and the vertebral arteries. NSRS disappeared in 126 pts (85.71%): contralateral ICA was non-stenotic in 32 cases (25.39%), stenotic < 75% in 68 cases (53.96%), stenotic > 75% in 7 cases (5.55%) and occluded in 19 cases (15.09%); vertebral arteries were pathological in only 6 cases (4.75%), among which 4 were on the same side and 2 on the opposite side of CE. NSRS persisted in 20 pts (13.6%): contralateral ICA was non-stenotic in 5 cases (25%), with a stenosis < 75% in 11 cases (55%) and with stenosis > 75% in 4 cases (20%); vertebral obliterative lesions were 3 (15.78%), among which 1 on the same and 2 on the opposite side of CE. No one statistical comparison among the groups of cases obtained on the ground of the status of ICA and vertebral arteries were significant (p always > 0.05 at chi-square analysis). Authors' data confirmed that high grade stenoses of ICA can cause NSRS and that CE--always performed at the aim to prevent major neurological attacks--can relieve also these functional disorders in the most of cases, independently from the status of the contralateral ICA and the vertebral arteries.

Monitoring of somatosensory evoked potentials during carotid endarterectomy: relationship with different haemodynamic parameters and clinical outcome

The authors studied the changes of Somatosensory Evoked Potentials (SEPs) performed in 241 anaesthetised patients during 264 carotid endarterectomies (CEs). SEP responses were considered significantly modified when the central conduction time was greater than 1 ms and/or when the amplitude of the complex N20-P25 decreased by at least 50%. Both CCT and N20-P25 have been correlated with different parameters, including the presence or absence of preoperative neurological deficits, the type of general anaesthesia, the status of the contralateral and the ipsilateral carotid artery, stump pressure, the use of an intraluminal shunt and the perioperative results. After carotid cross-clamping SEP responses were within the normal range in 236 CEs (89%), and abnormal in 28 (11%). A shunt was inserted 23 times in 264 (9%) cases. None of the patients operated on in this series experienced a permanent neurological deficit; there were three (1.1%) transient deficits (two Rinds and one TIA) and two deaths from non-neurological causes. Only one of the transient deficits was present when the patient woke from the anaesthetic and this event was predicted by significant modification of the SEP which did not reverse after removal of the clamps (a shunt was not used). None of the patients in our series who did not present significant modifications of SEPs during the operation had any postoperative neurological deficit. The authors conclude that SEP recording is a highly reliable and objective method for continuous monitoring of brain function during CE.