1,629 research outputs found
Partial inner product spaces: Some categorical aspects
We make explicit in terms of categories a number of statements from the
theory of partial inner product spaces (PIP spaces) and operators on them.
In particular, we construct sheaves and cosheaves of operators on certain PIP
spaces of practical interest.Comment: 21 page
Assessment of landfill leachate biodegradability and treatability by means of allochthonous and autochthonous biomasses
The biodegradability and treatability of a young (3 years old) municipal landfill leachate was evaluated by means of chemical oxygen demand (COD) fractionation tests, based on respirometric techniques. The tests were performed using two different biomasses: one cultivated from the raw leachate (autochthonous biomass) and the other collected from a conventional municipal wastewater treatment plant after its acclimation to leachate (allochthonous biomass). The long term performances of the two biomasses were also studied. The results demonstrated that the amount of biodegradable COD in the leachate was strictly dependent on the biomass that was used to perform the fractionation tests. Using the autochthonous biomass, the amount of biodegradable organic substrate resulted in approximately 75% of the total COD, whereas it was close to 40% in the case of the allochthonous biomass, indicating the capacity of the autochthonous biomass to degrade a higher amount of organic compounds present in the leachate. The autochthonous biomass was characterized by higher biological activity and heterotrophic active fraction (14% vs 7%), whereas the activity of the allochthonous biomass was significantly affected by inhibitory compounds in the leachate, resulting in a lower respiration rate (SOUR = 13 mg O2 gVSS-1 h-1 vs 37 mg O2 gVSS-1 h-1). The long-term performance of the autochthonous and allochthonous biomasses indicated that the former was more suitable for the treatment of raw landfill leachate, ensuring higher removal performance towards the organic pollutants
Effects of Supplemental Irrigation on Berseem Seed Crop in a Semi-Arid Mediterranean Environment
Berseem seed production in Mediterranean environments is strongly influenced by soil water availability, particularly during spring growth. A long-term study (11 years) in Sicily recorded seed yields of between 0 and 1600 kg/ha, for an annual rainfall range of 289 to 867 mm (Stringi et al., 2001). It was proposed that water irrigation during sensitive growth stages could increase and stabilize seed yield. This research investigated the response of berseem seed crop to low levels of irrigation applied at different growth stages
Preliminary evaluation of biopolymers production by mixed microbial culture from citrus wastewater in a MBR system using respirometric techniques
This preliminary study was aimed at evaluating the feasibility to produce biopolymers (BP) from citrus wastewater by mixed microbial culture in an anaerobic/aerobic membrane bioreactor (A/O-MBR). The activated sludge of the A/O-MBR was successfully enriched in microorganisms having a good capacity in producing intracellular biopolymers. The production of BP was found to be about 0.55 mgCOD mgCOD−1 using pure acetate at a concentration of 1000 mgCOD L−1. When using fermented wastewater, the conversion of acetate into BP product was 0.56 mgCOD mgCOD−1 in the test performed with C/N equal to 1000:1, whereas it was only 0.12 mgCOD mgCOD−1 in the test with C/N of 100:5. The results achieved suggested the feasibility to use citrus wastewater as a feedstock for biopolymers production although the low biomass storage capacity (0.26 mgCOD mgCODbiomass−1) suggested the need for optimizing the operating conditions in future studies
Three dimensional imaging of short pulses
We exploit a slightly noncollinear second-harmonic cross-correlation scheme
to map the 3D space-time intensity distribution of an unknown complex-shaped
ultrashort optical pulse. We show the capability of the technique to
reconstruct both the amplitude and the phase of the field through the coherence
of the nonlinear interaction down to a resolution of 10 m in space and 200
fs in time. This implies that the concept of second-harmonic holography can be
employed down to the sub-ps time scale, and used to discuss the features of the
technique in terms of the reconstructed fields.Comment: 16 pages, 6 figure
biogas from municipal solid waste landfills a simplified mathematical model
Abstract
Municipal solid waste (MSW) landfills now represent one of the most important issues related to the waste management cycle. Knowledge of biogas production is a key aspect for the proper exploitation of this energy source, even in the post-closure period. In the present study, a simple mathematical model was proposed for the simulation of biogas production. The model is based on first-order biodegradation kinetics and also takes into account the temperature variation in time and depth as well as landfill settlement. The model was applied to an operating landfill located in Sicily, in Italy, and the first results obtained are promising. Indeed, the results showed a good fit between measured and simulated data. Based on these promising results, the model can also be considered a useful tool for landfill operators for a reliable estimate of the duration of the post-closure period
Fouling mechanism elucidation in membrane bioreactors by bespoke physical cleaning
Cake layer deposition on a membrane surface can determine both external and internal membrane fouling through negatively affecting the total filtration resistance while exerting a positive effect as a pre-filter. Membranes are usually subjected to a periodic cake layer removal through routine physical cleaning, specifically permeate backwashing of hollow fiber membranes, or enhanced cleaning through, for example, chemically-enhanced backwashing. Physical cake layer removal is crucial for sustaining permeability, yet the effect of different physical cleaning modes remains poorly evaluated. The present work attempts to analyze physical cake layer removal through the application of specific cleaning methods and the impact of these on the subsequent resistance. The constituent contributions to the overall resistance are appraised by means of the Resistances In-Series model, with the aim of producing a robust protocol for quantifying these discrete contributors. The results, based in part on published data, show the proposed approach to reliably determine the relative contribution of the different resistance components to within 0.1 · 1012 m−1 across a range of different bench and pilot-scale plants, confirming the resilience of the method
MMP-2, MMP-9 and activin A blood levels in patients with breast cancer or prostate cancer metastatic to the bone.
Background: The clinical significance of the
circulating levels of activin A and matrix metalloproteinase-2
(MMP-2) and -9 (MMP-9) was investigated in patients with
breast cancer (BC) or prostate cancer (PC) with (M1) or
without (M0) bone metastasis. Patients and Methods: MMP-2,
MMP-9 and activin A blood concentrations were measured by
enzyme immunoassays in 79 cancer patients and in 57 healthy
blood donors (HS) who served as a control group. The
diagnostic accuracy of these molecules to discriminate between
M0 and M1 patients was evaluated by the receiver operating
characteristic curve (ROC) and compared to that of tumor
markers CA15.3 or prostate-specific antigen (PSA). Results:
Activin A and MMP-2 were significantly increased in BC and
PC patients as compared to sex-matched HS while MMP-9
levels were more elevated only in the PC patients. Interestingly,
in the PC patients, activin A levels were significantly higher than
those measured in the BC patients. In this latter group, activin A
and CA15.3 but not MMP-2 or MMP-9 were increased in the
M1 patients as compared to M0 patients. Furthermore, a
significant relationship was also highlighted between activin A
concentration and the number of bone metastases and tumor
grade, between MMP-9 and tumor grade, and between MMP-2
and CA15.3. ROC curve analysis showed a good diagnostic
accuracy for activin A and CA15.3 but a poor accuracy for
MMP-2 and MMP-9 in discriminating between M0 and M1
patients. However, CA15.3 retained the best diagnostic accuracy
in this respect. In the PC group, only activin A and PSA levels
were significantly increased in the M1 patients as compared to
the M0 patients. A similar although not statistically significant
trend was noted for MMP-9. Interestingly, a significant correlation
was observed between PSA and activin A and MMP-9, and
between Activin A and Gleason score and the number of
skeletal metastases. ROC curve analysis showed a good
diagnostic accuracy for activin A, MMP-9 and PSA and a poor
diagnostic accuracy for MMP-2 in detecting M1 patients.
However, PSA showed the highest diagnostic accuracy.
Conclusion: Activin A, MMP-2 and MMP-9 may be regarded as
possible therapeutic targets in the treatment of metastatic bone
disease. However, their usefulness as additional markers of bone
metastasis remains to be better define
Primary Pyomyositis as Unusual Cause of Limp: Three Cases in Immunocompetent Children and Literature Review
Treatment of high strength industrial wastewater with membrane bioreactors for water reuse: Effect of pre-treatment with aerobic granular sludge on system performance and fouling tendency
In this study, the treatment of citrus wastewater with membrane bioreactors (MBRs) under different configurations was investigated for water reuse. In particular, one MBR and one aerobic granular sludge MBR (AGS+MBR) bench scale plants were operated for 60 days. The experimental campaign was divided into two periods. In Phase I, a conventional hollow fiber MBR was employed for the treatment of the raw high strength wastewater, whereas in Phase II a combination of in-series reactors (AGS plus MBR) was adopted for the treatment of the high strength citrus wastewater
The results demonstrated that both plant configurations enabled very high COD removal, with average values close to 99%. Respirometric batch tests revealed a considerable high metabolic activity of the biomass in both plant configurations, with higher values in the AGS+MBR. It was speculated that the MBR reactor enriched in active biomass deriving from the erosion of the external granule layers in the upstream reactor. In terms of fouling tendency, higher resistance to filtration was observed in the AGS+MBR plant, also characterized by higher irremovable resistance increase compared to the MBR plant that might severely affect the membrane service life
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