An innovative ultrasound, Fe and TiO2 photoassisted process for bisphenol a mineralization

This paper explores the degradation of a model pollutant, bisphenol A, by an advanced oxidation process that combines sonolysis, Fe²⁺, and TiO₂ in a photoassisted process. Experiments were done under saturated oxygen conditions. The effect of different Fe²⁺ (0.56 and 5.6 mg/L) and TiO₂ (10 and 50 mg/L) concentrations was investigated on both the elimination and mineralization of the pollutant. A pronounced synergistic effect that led to the complete and rapid elimination of dissolved organic carbon (DOC) was observed even at low catalyst loadings. In this system, almost a complete removal of DOC (93%) was observed after 4 h using 10 and 5.6 mg/L of TiO₂ and Fe²⁺, respectively, whereas at the same time, only 5, 6, and 22% of DOC was removed by an individual process alone (TiO₂ photocatalysis, ultrasound, and photo-Fenton, respectively). In this system, ultrasound has the principal role of eliminating the initial substrate and providing hydrogen peroxide for the photocatalytic systems, while photo-Fenton and TiO₂ photocatalysis are mainly responsible for the transformation of the intermediates in CO₂ and H₂O. The role of H₂O₂ generated from the sonochemical process is also discussed.     

Proceedings of the eleventh annual meeting of the arizona society for electron microscopy and microbeam analysis held in tucson,arizona, february 7–8, 1990

The ultrastructure of the progressive testicular involution with advancing age in men is reviewed. There is no definite age at which testicular involution begins, and the onset and severity of testicular lesions are subjected to pronounced individual variations. Hormone studies also indicate great individual variations, and subtle changes in both the testis and the pituitary develop progressively with age. Testicular size, sperm quality, and numbers of all germ cell types, Sertoli cells, and Ley dig cells decrease with age. The volume occupied by the seminiferous tubules decreases, whereas that occupied by the testicular interstitium remains constant. The most frequent histological pattern of the aging testis is a mosaic of different seminiferous tubule lesions, varying from tubules with complete, although reduced, spermatogenesis, to completely sclerosed tubules. The tubules with complete spermatogenesis may show numerous morphological abnormalities in the germ cells, including multinucleation. Abnormal germ cells degenerate causing Sertoli cell vacuolation. These vacuoles correspond to dilations of the extracellular spaces resulting from the premature exfoliation of germ cells. Degenerating cells that are phagocytosed by the Sertoli cells give rise to an accumulation of lipid droplets in the Sertoli cell cytoplasm. The loss of germ cells begins with the spermatids, but progressively affects the earlier germ cell types, and tubules with maturation arrest at the level of the spermatocytes or spermatogonia are observed. The Sertoli cells show morphological abnormalities such as dedifferentiation, mitochondrial metaplasia, and multinucleation. Germ cell loss is associated with thickening of the tunica propria. When all seminiferous epithelial cells have disappeared, only an intensely collagenized tunica propria with myoid cells remains (sclerosed tubules). The Ley dig cells progressively dedifferentiate with a decrease in the quantity of both smooth endoplasmic reticulum and mitochondria, together with an accumulation of lipid droplets, crystalline inclusions, and residual bodies, and formation of multinucleate cells. The development of tubular involution with age is similar to that observed after exprimental ischemia, suggesting that vascular lesions may play an important role in age-related testicular atrophy.     

Acceleration‐Based Automated Vehicle Classification on Mobile Bridges

Mobile bridges have been used for a broad range of applications including military transportation or disaster restoration. Because mobile bridges are rapidly deployed under a wide variety of conditions, often remaining in place for just minutes to hours, and have irregular usage patterns, a detailed record of usage history is important for ensuring structural safety. To facilitate usage data collection in mobile bridges, a new acceleration‐based vehicle classification technique is proposed to automatically identify the class of each vehicle. Herein we present a new technique that is based on the premise that each class of vehicles produces distinctive dynamic patterns while crossing this mobile bridge, and those patterns can be extracted from the system's acceleration responses. Measured acceleration signals are converted to time–frequency images to extract two‐dimensional patterns. The Viola–Jones object detection algorithm is applied here to extract and classify those patterns. The effectiveness of the technique is investigated and demonstrated using laboratory and full‐scale mobile bridges by simulating realistic scenarios.     

Pro-poor tax policy and yardstick competition: a spatial investigation for VAT relief on food in Brazil

This paper investigates whether a pro-poor tax policy follows yardstick competition in the value-added tax (VAT) base in Brazilian states. We explore an institutional arrangement that allows lower levels of government to set tax relief (tax cuts and exemptions) for food goods in a so-called basic basket food. Next, we examine the relationship between the VAT and the ‘Fund Against Poverty’ (FAP) financed by VAT rate increases on cigarettes and gas. Our findings indicate that the state tax function responds positively to the neighbour’s redistributive policy. Moreover, we estimate that the degree of spatial tax interaction among states has increased since the establishment of the FAP, suggesting that FAP resources are viewed as a complementary pro-poor policy rather than either a fiscal equalisation (substitute policy) or a possible slackness in the constraint of redistributive policies.     

Steel beam-column connection using copper-based shape memory alloy dampers

This study presents the details of an experimental investigation on a prototype partially restrained connection using copper-based shape memory alloy (SMA) bars. The proposed configuration consists of an end-plate connection between a rectangular hollow structural steel beam and a wide flange steel column, where four CuAlBe () bars, in austenitic phase, are used to prestress the end-plate to the column flange. A physical model of the connection was tested by applying a controlled cyclic displacement history at the tip of the beam with two different characteristic frequencies of 0.25 and 1 Hz. Potentiometers and load cells were used to measure strains and stresses in the bars and the displacement and load applied at the beam tip. Similar bars, with the same thermal treatment, had been previously tested in cyclic tension at several nominal strains and frequencies, showing superelastic behavior for deformations up to 2.3% strain. In static tensile tests, the fracture strain was approximately 8%, with a transgranular fracture mechanism. The equivalent damping ratio for the single bar test increases for larger strains, being 6% for a 2.3% strain. The beam-column connection also exhibited superelastic behavior, a moderate level of energy dissipation, and no strength degradation after being subjected to several cycles up to 3% drift. Finally, a set of numerical simulations are conducted to compare the performance of a rigid steel frame and a partially restrained frame with SMA connections using a three-story benchmark structure.     

Characterization of Enterococcus faecalis-infecting phages (enterophages) as markers of human fecal pollution in recreational waters

Enterophages are a novel group of phages that specifically infect Enterococcus faecalis and have been recently isolated from environmental water samples. Although enterophages have not been conclusively linked to human fecal pollution, we are currently characterizing enterophages to propose them as viral indicators and possible surrogates of enteric viruses in recreational waters. Little is known about the morphological or genetic diversity which will have an impact on their potential as markers of human fecal contamination. In the present study we are determining if enterophages can be grouped by their ability to replicate at different temperatures, and if different groups are present in the feces of different animals. As one of the main objectives is to determine if these phages can be used as indicators of the presence of enteric viruses, the survival rate under different conditions was also determined as was their prevalence in sewage and a large watershed. Coliphages were used as a means of comparison in the prevalence and survival studies. Results indicated that the isolates are mainly DNA viruses. Their morphology as well as their ability to form viral plaques at different temperatures indicates that several groups of enterophages are present in the environment. Coliphage and enterophage concentrations throughout the watershed were lower than those of thermotolerant coliforms and enterococci. Enterophage concentrations were lower than coliphages at all sampling points. Enterophages showed diverse inactivation rates and T₉₀ values across different incubation temperatures in both fresh and marine waters and sand. Further molecular characterization of enterophages may allow us to develop probes for the real-time detection of these alternative indicators of human fecal pollution.     

Structural optimization for performance-based design in earthquake engineering: Applications of neural networks

This work addresses an approach to performance-based design in the context of earthquake engineering. The objective is the optimization of the total structural cost, under constraints related to minimum target reliabilities specified for the different limit states or performance requirements. The problem involves (1) the use of a nonlinear, time-stepping dynamic analysis to investigate the responses of relevance to the performances’ evaluation and (2) the integration of the responses into measures of damage accumulated during the earthquake. The random responses are deterministically obtained for different combinations of the design parameters and the intervening random variables, of which some are associated with the structure and some with the earthquake characteristics. The approach uses a neural network representation of the responses and, for each one, the variability associated with different earthquake records is accommodated by developing two networks: one for the mean response over the records, and another for the corresponding standard deviation. The neural network representation facilitates the estimation of reliability by Monte Carlo simulation, and the reliability achieved in each performance level, for a specific combination of the design parameters, is itself represented with a neural network. This is then used within an optimization algorithm for minimum total cost under reliability constraints. An application example uses a reinforced concrete, multi-storey plane structure with seismic demands corresponding to the city of Mendoza, Argentina.     

Improved probabilistic quantification of drift demands for seismic evaluation

This study deals with the evaluation and formulation of methods to improve the probabilistic quantification of maximum story drift demands for structural systems exposed to severe ground motions. The focus is on flexible structures that are prone to dynamic instability. The quantification of drift demands is based on the probability distribution of the maximum story drift over the height, for a given ground motion hazard level, which in this study is represented by the spectral acceleration at the first mode period of the building. Improvements in the probabilistic estimation of maximum story drift demands are illustrated with a nine-story, moment-resisting frame building exposed to a set of 40 ground motions. It is concluded that (1) the three-parameter LN distribution more rationally describes maximum story drifts at higher values of spectral acceleration; (2) statistically adding values to replace truncated data points provides better goodness-of-fit in maximum drift demand prediction when the structure is close to the onset of dynamic instability, and (3) the least-squares fitting of the LN distribution yields parameters that provide an improved fit compared to that from maximum likelihood estimation and the method of moments.     

Silver contamination on abiotic and biotic compartments of Nahuel Huapi National Park lakes, Patagonia, Argentina

The Ag contents of abiotic and biotic compartments of different lakes of Nahuel Huapi National Park, Patagonia, Argentina were analyzed. The water bodies studied were lakes Nahuel Huapi, Moreno, Escondido, Espejo Chico and Traful, the latter chosen as a reference lake. The Ag concentration profiles of short sediment cores, dated by (210)Pb and (137)Cs techniques, were analyzed, as well as suspended load collected from three sites of lake Nahuel Huapi. The biota studied were the native mussel Diplodon chilensis (digestive gland and total soft tissues pooled samples) and five species of fish, two native and three introduced (liver and muscle pooled samples). Ag contents were determined by Instrumental Neutron Activation Analysis (INAA). The upper layers of the sediment cores sampled in lake Nahuel Huapi were enriched in Ag contents compared to deep layers in accumulation periods corresponding to the second half of the 20th century, but this enrichment was neither observed in the reference lake Traful, nor in lakes Espejo Chico and Escondido. Ag was enriched over background level (0.1 microg g(-1)) also in suspended load collected in lake Nahuel Huapi. Ag fluxes to sediments were computed for suspended load and enriched sediment core layers. Highest Ag fluxes, from 350 to 470 microg m(-2) year(-1), were measured in Nahuel Huapi near the site where the liquid effluents of the Bariloche city sewage treatment plant are released to the lake. The spatial distribution of the other Ag fluxes suggests that this is the main source of Ag to lake Nahuel Huapi and lateral transport occurs within the water body. Ag concentrations on biota samples were consistent with these conclusions. Mussels collected in lake Nahuel Huapi showed higher Ag concentrations than in the other lakes, especially when compared to lake Traful. Ag contents in mussels were strongly associated with sediment intake, but enriched probably due to sediment grain size sorting during the intake processes. Evidence of food chain biomagnification of Ag in fish liver was observed. Ag contents in fish liver were higher at lake Nahuel Huapi even considering the high intra-specific variability, with highest values ranging from 10 to 29 microg g(-1) dry weight for brown trout and rainbow trout.     

Comparison of next-generation portable pollution monitors to measure exposure to PM2.5 from household air pollution in Puno,Peru

Assessment of personal exposure to PM_2.5 is critical for understanding intervention effectiveness and exposure-response relationships in household air pollution studies. In this pilot study, we compared PM_2.5 concentrations obtained from two next-generation personal exposure monitors (the Enhanced Children MicroPEM or ECM; and the Ultrasonic Personal Air Sampler or UPAS) to those obtained with a traditional Triplex Cyclone and SKC Air Pump (a gravimetric cyclone/pump sampler). We co-located cyclone/pumps with an ECM and UPAS to obtain 24-hour kitchen concentrations and personal exposure measurements. We measured Spearmen correlations and evaluated agreement using the Bland-Altman method. We obtained 215 filters from 72 ECM and 71 UPAS co-locations. Overall, the ECM and the UPAS had similar correlation (ECM ρ = 0.91 vs UPAS ρ = 0.88) and agreement (ECM mean difference of 121.7 µg/m³ vs UPAS mean difference of 93.9 µg/m³) with overlapping confidence intervals when compared against the cyclone/pump. When adjusted for the limit of detection, agreement between the devices and the cyclone/pump was also similar for all samples (ECM mean difference of 68.8 µg/m³ vs UPAS mean difference of 65.4 µg/m³) and personal exposure samples (ECM mean difference of −3.8 µg/m³ vs UPAS mean difference of −12.9 µg/m³). Both the ECM and UPAS produced comparable measurements when compared against a cyclone/pump setup.