Reducing energy demand by the combined application of advanced control strategies in a full scale WWTP.

Two advanced control strategies were applied in the secondary and tertiary stages, respectively, of a full scale wastewater treatment plant (WWTP). This has a nominal capacity of 330,000 population equivalent (PE), a complex configuration (having been upgraded several times through the years), and it faces significant seasonal load fluctuations (being located in a touristic area, in Northern Italy). The lifting station of the tertiary treatments (devoted to phosphorus precipitation and UV disinfection) was optimized by adjusting the pumped flowrate, depending on influent phosphorus concentration. A preliminary simulation showed that a 15% reduction of pumping energy could be achieved. This result was confirmed by field measurements. Moreover, a fuzzy control system was designed and applied to one of the six parallel nitrification reactors, yielding a reduction of more than 25% of the power requirement for aeration. Overall, the combined application of the two controllers led to a 7% reduction of the total energy consumption of the plant. This result is particularly promising given that the fuzzy controller was applied only to one of six biological reactors.

Energy saving for air supply in a real WWTP: application of a fuzzy logic controller.

An unconventional cascade control system, for the regulation of air supply in activated sludge wastewater treatment plants (WWTPs), was tested. The dissolved oxygen (DO) set point in the aeration tank was dynamically calculated based on effluent ammonia concentration, following a fuzzy logic based approach. First, simulations were conducted, according to the BSM2 protocol, for a general comparison with more conventional control strategies. It turned out that the effluent quality could be improved by 7-8%, based on the EQI parameter. Moreover, the aeration energy requirement could be reduced up to 13%. Subsequently, the system was installed in a full-scale WWTP. While stably complying with the ammonia effluent standard (10 mg/L), excess air supply was prevented, and a reduction of the specific power consumption (kWh/kgCODremoved) of 40-50% was recorded with respect to the previously installed PID controller (fixed DO set point).

Hidden solidlike properties in the isotropic phase of the 8CB liquid crystal.

Novel dynamic experiments have enabled the identification of a macroscopic solidlike response in the isotropic phase of a low molecular weight liquid crystal, 4,4'-n-octylcyanobiphenyl (8CB). This unknown property indicates that the low frequency shear elasticity identified in the isotropic phase of liquid crystal polymers is not reminiscent from the glass transition but reveals likely a generic property of the liquid state. The comparison to high molecular weight liquid crystals indicates, however, that the shear modulus is much enhanced when the liquid crystal moieties are attached to a polymer chain. The macroscopic length scales probed (0.050-0.100 mm) exclude wall-induced effects.

Liquid phase deposition of polymers on arbitrary shaped surfaces and their suitability for e-beam patterning.

We present a straightforward low cost liquid phase deposition method to coat arbitrary-shaped dielectric substrates with uniform electron beam sensitive polymer films. Furthermore, we investigate the use of electron beam lithography to pattern the coated pre-form substrates. The polymers studied are poly-methyl-methacrylate with different molecular weights, poly(methyl methacrylate-co-ethyl acrylate) and methyl methacrylate. The polymer coverage over the whole surface area is shown to be uniform and the thickness of the film dependent on the concentration of the polymer liquid used. As the uniform polymer layer is deposited on non-flat surfaces, we show that with an electron beam various surfaces, e.g. microlens arrays, can be re-patterned accurately with nanoscale features. Furthermore, we show the required dose for electron beam exposure to be dependent on the concentration and on the molecular weight of the polymer used.

Performance evaluation and assessment of receiver impairments of a novel PolSK transceiver based on differential demodulation.

We present a novel transceiver setup for Polarization Shift Keying (PolSK) modulation using a simple transmitter and a receiver based on differential demodulation. The transmitter is made up of a LiNbO(3) phase modulator with the input fiber pigtailed at 45 degrees with respect to the principal axes of the modulator. The receiver is composed of an asymmetric Mach-Zehnder Interferometer (AMZI) and a couple of balanced photodetectors (BPD), as usually employed for receiving DPSK. To our knowledge, it is the first time such receiver structure is applied to PolSK. In order to fully assess the system performance of the proposed setup, we have carried out numerical simulations using a semi-analytical technique for bit-error-rate evaluation and performed experimental measurements at 10 Gbit/s. After having optimized transceiver performances, we evaluated the resilience to receiver impairments to verify the viability of a realistic implementation. Surprisingly, PolSK shows a better sensitivity using a single-end receiver (with the AMZI tuned at the minimum transmittance point) than using a balanced one. Another improvement has been obtained optimizing the driving voltage at the transmitter: this leads to a "non-ideal" PolSK modulation with non-orthogonal symbols, which shows an enhanced performance thanks to a synchronous phase modulation.

8B10B line coding to mitigate the non-uniform FM laser response of direct modulated CPFSK transmitter.

We propose to employ 8B10B line coding as a simple technique to mitigate the impact of non-uniform laser diode FM response on the system performance of directly-modulated CPFSK. Experimental results show its effectiveness in decreasing signal distortion and penalty.

Pressure effects revealed by small angle neutron scattering on block copolymer gels.

We study the effects of hydrostatic pressure (P) on aqueous solutions and gels of the block copolymer B(20)E(610) (E, oxyethylene; B, oxybutylene; subscripts, number of repeats), by performing simultaneous small angle neutron scattering/pressure experiments. Micellar cubic gels were studied for 9.5 and 4.5 wt % B(20)E(610) at T = 20-80 and 35-55 degrees C, respectively, while micellar isotropic solutions where studied for 4.5 wt % B(20)E(610) at T > 55 degrees C. We observed that the interplanar distance d 110 (cubic unit cell parameter a = [see text for formula]) decreases while the correlation length of the cubic order (delta) increases, upon increasing P at a fixed T for 9.5 wt % B(20)E(610). The construction of master curves for d(110) and delta corresponding to 9.5 wt % B(20)E(610) proved the correlation between changes in T and P. Neither d(110) and delta nor the cubic-isotropic phase transition temperature was affected by the applied pressure for 4.5 wt % B(20)E(610). The dramatic contrast between the pressure-induced behavior observed for 9.5 and 4.5 wt % B(20)E(610) suggests that pressure induced effects might be more effectively transmitted through samples that present wider domains of cubic structure order (9.5 wt % compared to 4.5 wt % B(20)E(610)).

Evaluation of batch adsorption of chromium ions on natural and crosslinked chitosan membranes.

Removal of chromium ions from aqueous solutions by using natural and crosslinked chitosan membranes was achieved using batch adsorption experiments. The effect of pH (6.0 and 2.0), concentration of chromium ions and crosslinking agents (glutaraldehyde: GLA and epichlorohydrin: ECH) on the adsorption properties of chitosan membranes was analyzed. The experimental equilibrium data was fitted to Langmuir and Freundlich models. Through the model curves, it was possible to observe that the amount of chromium ions adsorbed was significantly higher for crosslinked membranes compared to non-crosslinked chitosan. The maximum adsorbed amount was about 1400 mg g(-1) for ECH-crosslinked chitosan at pH 6.0. The adsorption rates for crosslinked chitosan membranes with glutaraldehyde and epichlorohydrin were similar for natural chitosan. Desorption study using NaCl (1 mol L(-1)) solution was performed on chitosan membranes, in order to recover chromium ions and to determine the suitable number of cycles for repeated use of these membranes without considerable decrease in their adsorption capacity. The desorption results showed that chromium ions could be more effectively removed at pH 2.0 than pH 6.0, mainly for ECH-crosslinked chitosan.

A mathematical model for the prediction of solute kinetics, osmolarity and fluid volume changes during hemodiafiltration with on-line regeneration of ultrafiltrate (HFR).

Hemodiafiltration with on-line regeneration of ultrafiltrate (HFR) is a technique indicated for the treatment of dialysis patients affected by inflammatory syndrome and malnutrition. In the present work, a mathematical model, which describes intradialytic fluid and solute kinetics during standard diffusive dialysis, has been adapted to analyze solutes and fluid dynamics during HFR. The model is an improved version of our previous ones, and represents a good compromise between simplicity and reliability. It considers the intradialytic kinetics of sodium, potassium and urea, and two body fluid compartments: intracellular and extracellular. Moreover, the model includes simple equations to predict the intradialytic time pattern of osmolarity. The model has been experimentally validated by using 9 HFR sessions on 9 patients (one per each patient), comparing the time course of plasma solutes and osmolarity measured every 30 minutes during HFR, with those predicted by the model. Predictions are performed a priori, i.e., without any parameter adjustment, but just starting from knowledge of a few quantities (plasma sodium, potassium, urea, osmolarity and body weight) at the beginning of the session. The average deviations between model and real data (sodium: 1.9 mEq/L; potassium: 0.32 mEq/L; urea: 1.04 mmol/L; osmolarity: 5.02 mosm/L) are of the same order as measurement errors and similar to those obtained using our previous models in standard and profiled hemodialysis. Moreover, the prediction on sodium concentration only scarcely worsens (from 1.9 to 2.02 mEq/L) if default values are used for the initial value of other solutes in blood (i.e., if the algorithm uses only initial body weight and initial sodium concentration in plasma). The results confirm the good predictive capacity of the model in HFR, and suggest its possible innovative use to optimize sodium balance in HFR, from knowledge of only the sodium concentration in the ultrafiltrate.

Process improvement and energy saving in a full scale wastewater treatment plant: air supply regulation by a fuzzy logic system.

Achieving good performance in air supply control is an important goal in the management of wastewater treatment plants, whose highly nonlinear behaviour makes the application of conventional control techniques problematic. This paper presents the development and experimentation of a fuzzy logic system for air supply regulation in a full scale municipal wastewater treatment plant. The system is composed of two main modules, one devoted to continuously adjusting the DO set point on the basis of the current effluent NH4(+)-N concentration (on-line measurement), and the other devoted to achieve the DO set point by controlling air supply devices. The experiment was carried out on the plant for about one year, leading to significant advantages in terms of both process stability and energy saving.

The frozen state in the liquid phase of side-chain liquid-crystal polymers.

Quenched isotropic melts of side-chain liquid-crystal polymers reveal surprisingly an anisotropic polymer conformation. This small-angle neutron-scattering (SANS) result is consistent with the identification of a macroscopic, solidlike response in the isotropic phase. Both experiments (rheology and SANS) indicate that the polymer system appears frozen on millimeter length scales and at the time scales of the observation. This result implies that the flow behavior is not the terminal behavior and that cross-links or entanglements are not a necessary condition to provide elasticity in melts.

Solid-like rheological response of non-entangled polymers in the molten state.

We show that non-entangled polymers display an elastic-like behaviour at a macroscopic scale (probed at some 0.100 mm thickness) up to at least hundred degrees above the glass transition temperature. This observation, found under non-slippage conditions, both for side-chain liquid crystalline polymers and ordinary polymers, is in contradiction with the typically found flow behaviour of polymer melt. Our measurements were carried out with a conventional rheometer at thicknesses of several tenths millimetres. Thus, we were probing bulk properties. The observed elasticity supposedly implies that even in the melt the chains experience a cohesive effect of macroscopic distances, involving collective motions over time scales longer than the individual relaxation time of an individual polymer chain. The detection of such a solid-like property of molten non-entangled polymers is of considerable importance for a better understanding of the polymer dynamics.

Pressure-induced reduction of the Landau-Peierls instabilities in a side-chain polymer liquid crystal with reentrant polymorphism.

Cyanobiphenyl mesogens are known to exhibit partially bilayered smectic A (S(Ad)) and also reentrant nematic (N(re)) phases. Nematic and smectic orders are coupled parameters which depend both on temperature and pressure. We report the first structural study of the influence of a hydrostatic pressure on the smectic phase. This study was carried out on a side-chain liquid crystalline polymer, by neutron diffraction using two specifically designed pressure cells. These results concluded first that the pressure acts on the phase elastic constants via a reduction of the layer fluctuations giving rise to a hardening of the phase together with an extension of the smectic domain towards higher temperatures. Second, the S(Ad)-N(re) phase transition temperature remains unchanged in the studied pressure range revealing that the polymer component plays an important role which allows us to subtract the associated packing interactions from the pressure-induced volume reduction.

Managing uncertainty in diagnosis of acute coronaric ischemia.

The paper presents the reasoning mechanism of COR, a knowledge-based system (KBS) able to provide support for the diagnosis of coronaric ischemia by integrating the interpretation of chest pain, 12-lead ECG, and bio-marker concentrations. Chest pain features are collected interactively through a questionnaire. The ECG signal is acquired in SCP format. Any set of bio-markers can be considered. Data input is incremental and possibly incomplete. Reasoning is based on revised uncertainty calculus, which allows a formal treatment of verbally expressed uncertainty concerning both input data and diagnostic rules. Each diagnosis is supplemented by a linguistic label, expressing the plausibility of the disease identified, given the symptoms observed.

[Secondary serologic responses to dengue epidemic in 1998 in Salta, Argentina, where other flavivirus co-circulate]. / Respuestas serológicas secundarias en la epidemia de dengue de 1998 en Salta, Argentina, donde co-circulan otros flavivirus.

In 1998, a dengue outbreak (serotype 2) occurred in Salta province in Northern Argentina, following the first detection of dengue in the same area in 1997. We classified the serologic response of cases from 1998 as primary or secondary, since the risk of severe disease is greater for secondary cases. We studied 154 cases by plaque reduction neutralization and hemagglutination inhibition tests. Thirty-eight cases (25%) were classified as primary serologic responses and 84 cases (54%) as secondary responses. Thirty-two cases (21%) with borderline IgG titers could not be classified. Previous exposure to potentially cross-reacting flaviviruses (Saint Louis Encephalitis [SLE] and Yellow Fever [YF] viruses) was analyzed, as a possible cause of the secondary response pattern. Our results indicated that among cases classified as dengue secondary response, 83% could be attributed to previous SLE or YF exposure or serologic cross-reactivity. Vaccination against YF virus was at most a minor contributor to the secondary response pattern. The finding of a positive YF serologic result among persons not vaccinated may indicate silent circulation of YF in a region that can support both urban and jungle cycles. Other cases showing dengue secondary responses remained unexplained, suggesting the unrecognized occurrence of a previous infection with other dengue serotypes or of flaviviruses other than SLE or YF.

Respuestas serológicas secundarias en la epidemia de dengue de 1998 en Salta, Argentina, donde co-circulan otros flavivirus. / [Secondary serologic responses to dengue epidemic in 1998 in Salta, Argentina, where other flavivirus co-circulate]

In 1998, a dengue outbreak (serotype 2) occurred in Salta province in Northern Argentina, following the first detection of dengue in the same area in 1997. We classified the serologic response of cases from 1998 as primary or secondary, since the risk of severe disease is greater for secondary cases. We studied 154 cases by plaque reduction neutralization and hemagglutination inhibition tests. Thirty-eight cases (25

) were classified as primary serologic responses and 84 cases (54

) as secondary responses. Thirty-two cases (21

) with borderline IgG titers could not be classified. Previous exposure to potentially cross-reacting flaviviruses (Saint Louis Encephalitis [SLE] and Yellow Fever [YF] viruses) was analyzed, as a possible cause of the secondary response pattern. Our results indicated that among cases classified as dengue secondary response, 83

could be attributed to previous SLE or YF exposure or serologic cross-reactivity. Vaccination against YF virus was at most a minor contributor to the secondary response pattern. The finding of a positive YF serologic result among persons not vaccinated may indicate silent circulation of YF in a region that can support both urban and jungle cycles. Other cases showing dengue secondary responses remained unexplained, suggesting the unrecognized occurrence of a previous infection with other dengue serotypes or of flaviviruses other than SLE or YF.

[Outbreak of Dengue-2 virus in Salta, Argentina, 1988]. / Epidemia por virus dengue-2 en Salta, Argentina, 1998.

Dengue (DEN) reemergence was first detected in Salta, Argentina, in 1997. It was confirmed by serology and PCR that DEN-2 virus was responsible for sporadic cases and indigenous transmission. A laboratory-based surveillance system allowed the detection of an outbreak in Salta several months later. In total, 378 DEN cases were laboratory diagnosed out of 646 (58%) studied. The cases were distributed in 10 localities of the province between January 3rd and May 31st, 1998. One DEN-2 viral isolation and 4 PCR products were obtained from patients coming from Orán and Embarcación localities. Male and female cases occurred at a similar rate (1:1), with adult cases (82.5%) nearly five times greater than for children under 15 years-old (17.5%). Clinically, all cases corresponded to classic DEN. This is the first time that a DEN outbreak has been laboratory-diagnosed in Argentina and also the first time that DEN virus has been isolated in this country.

Epidemia por virus dengue-2 en Salta, Argentina, 1998. / [Outbreak of Dengue-2 virus in Salta, Argentina, 1988]

Dengue (DEN) reemergence was first detected in Salta, Argentina, in 1997. It was confirmed by serology and PCR that DEN-2 virus was responsible for sporadic cases and indigenous transmission. A laboratory-based surveillance system allowed the detection of an outbreak in Salta several months later. In total, 378 DEN cases were laboratory diagnosed out of 646 (58

) studied. The cases were distributed in 10 localities of the province between January 3rd and May 31st, 1998. One DEN-2 viral isolation and 4 PCR products were obtained from patients coming from Orán and Embarcación localities. Male and female cases occurred at a similar rate (1:1), with adult cases (82.5

) nearly five times greater than for children under 15 years-old (17.5

). Clinically, all cases corresponded to classic DEN. This is the first time that a DEN outbreak has been laboratory-diagnosed in Argentina and also the first time that DEN virus has been isolated in this country.

Dengue reemergence in Argentina.

Aedes aegypti, eradicated from Argentina in 1963, has now reinfested the country as far south as Buenos Aires. In 1997, four persons with travel histories to Brazil, Ecuador, or Venezuela had confirmed dengue, and surveillance for indigenous transmission allowed the detection of 19 dengue cases in Salta Province. These cases of dengue are the first in Argentina since 1916 and represent a new southern extension of dengue virus.

[Varicocele and its repercussion on infertility. Indications and limitations of surgical intervention]. / Varicocele e sue ripercussioni sulla sterilità. Indicazioni e limiti dell'intervento chirurgico.

According to different Authors, varicocele incidence in unselected population fluctuates from 8 to 22% but in selected population affected by sterility incidence ranges from 21 to 39%. However other Authors have demonstrated that about 50% of patients suffering from varicocele have semen alterations. Various mechanisms have been suggested for testicular dysfunction associated with varicocele: intrascrotal hyperthermia, reflux of renal and adrenal metabolites from the renal vein and hypoxia. The most important semen alterations are observed in patients suffering from grade 2 and 3 varicocele and especially these patients must undergo surgical operation. According to recent findings, better results about the improvement of semen quality are obtained by operating children in puberal age. This clinical approach allows a prevention of testicular hypotrophy or, when this is already present, its reversibility. Varicocele surgical treatment makes use of traditional techniques microsurgical or not and mininvasive techniques. After renouncing of intrascrotal varicocelectomy, traditional techniques provide ligature and section of ectasic spermatic veins, after a surgical high (at level of the internal inguinal ring) or low (over inguinal canal) skin incision. Microsurgery allows recognition and protection of lymphatic and arterial vessels and execution of microsurgical anastomosis between venous spermatic and ileo-femoral circle vessels, when this is necessary. Internal spermatic vessels and vas deferens can be visualized through the laparoscope and so laparoscopic varicocele treatment was suggested. These new techniques and traditional operation are burdened with the same percentage of relapses but in laparoscopic procedure complications are more important. Recently radiographic occlusion techniques are also utilized (internal spermatic vein retrograde scleroembolization); the percentage of relapses is between 4 and 11%, with no risk of postvaricocelectomy hydrocele but with risk of loss of kidney (migration of the ballon or coil into the renal vein). Surgical treatment of varicocele produces a significant improvement in semen analysis in 60 to 80 per cent of patients affected by testicular dysfunction. Pregnancy rates after varicocelectomy are including from 20 to 60 per cent with most series averaging about 35 per cent.