Impact of SWMM Fouling and Position on the Performance of SWRO Systems in Operating Conditions of Minimum SEC

Due to water stress in the world in general desalination technologies are becoming increasingly important. Among the available technologies, reverse osmosis (RO) is the most widespread due to its reliability and efficiency compared to other technologies. The main weakness of RO is the loss of performance due to membrane fouling, which usually affects the water permeability coefficient (A), causing it to decrease. In RO desalination plants, fouling does not affect all spiral wound membrane modules (SWMMs) in the pressure vessels (PVs) in the same way. This will depend on the type of fouling and the position of the SWMM inside the PV. In this study, the impact of A and the position of the SWMM on the performance of the RO system is analyzed. For this purpose, decrements of up to 50% have been assumed for the seven SWMMs in series considering nine commercial SWMM models. The operating point analyzed is that which minimizes the specific energy consumption (SEC), a point obtained in a previous work carried out by the authors. The results show how the impact of A on the SWMM in the first position is more significant than the impact on modules that are in another position for the nine SWRO models studied. A drop of 50% in the coefficient A of the first element produces a permeate loss in the pressure pipe between 0.67 and 1.35 m3 d-1. Furthermore, it was observed that the models with the lowest coefficient A exhibited the highest performance losses in terms of permeate production when A was decreased.

Tasas de letalidad por SARS-CoV-2 según Comunidades Autónomas durante la segunda onda epidémica en España

Introducción

En España, los sistemas sanitarios están transferidos a las Comunidades Autónomas (CC.AA.), constituyendo 19 sistemas sanitarios con gestión y recursos diferenciados. Durante la primera onda epidémica de la COVID-19 se objetivaron diferencias en los sistemas de declaración y en las tasas de letalidad (TL) entre las CC.AA. El objetivo de este estudio fue analizar las TL por CC.AA. durante la segunda onda epidémica (del 20 de julio al 25 de diciembre de 2020) y su relación con la prevalencia de la infección.

Material y métodos

Se realizó un estudio observacional descriptivo con la información disponible sobre el número de fallecidos por COVID-19 registrados en el Ministerio de Sanidad, Consejerías de Salud y los Departamentos de Salud Pública de las CC.AA. y según el exceso de mortalidad informado por el Sistema de Monitorización de Mortalidad Diaria (MoMo). La prevalencia de la infección se estimó a partir de las diferencias entre la segunda y cuarta ronda del estudio ENE-COVID y sus intervalos de confianza del 95%. Se calcularon las TL (fallecidos por cada mil infectados) globales, por sexo, grupos de edad (< 65 y ≥ 65 años) y CC.AA. Se calculó la razón estandarizada de letalidad por edad (REL) de las CC.AA. utilizando las TL de España para cada grupo de etario. Estas estimaciones se realizaron con las defunciones declaradas oficialmente (TLo) y el exceso de defunciones estimadas por MoMo (TLMo). Se estimaron las correlaciones entre las prevalencias de infección y las TLo y TLMo, ponderando por población.

Resultados

Para el conjunto de España, la TLo durante la segunda onda epidémica fue del 7,6%, oscilando entre 3,8% de Baleares y 16,4% de Asturias, y la TLMo fue de 10,1%, oscilando entre el 4,8% de Madrid y el 21,7% en Asturias. Se observaron diferencias significativas entre la TLo y la TLMo en Canarias, Castilla la Mancha, Extremadura, Comunidad Valenciana, Andalucía y las Ciudades Autónomas de Ceuta y Melilla. La TLo fue significativamente mayor en hombres (8,2%) que en mujeres (7,1%). Las TLo y TLMo fueron significativamente mayores en el grupo de edad ≥ 65 años (55,4 y 72,2%, respectivamente) que en el grupo < 65 años (0,5 y 1,4%, respectivamente). País Vasco, Aragón, Andalucía y Castilla la Mancha presentaron una REL significativamente superiores a uno. Las correlaciones entre la prevalencia de infección y las TLo fueron inversas.

Conclusiones

La letalidad por COVID-19 durante la segunda onda epidémica en España mejoró respecto a la primera. Los datos disponibles sugieren que la letalidad de la segunda onda en las CC.AA. estaría influida por la elevada letalidad observada en la primera onda en personas con comorbilidades, así como por las limitaciones de los sistemas de detección y notificación de SARS-CoV-2. Las tasas de letalidad fueron mayores en hombres y personas mayores, y variaban significativamente entre CC.AA. Es necesario profundizar en el análisis de las causas de estas diferencias.

Thermodynamic Limitations and Exergy Analysis of Brackish Water Reverse Osmosis Desalination Process

The reverse osmosis (RO) process is one of the most popular membrane technologies for the generation of freshwater from seawater and brackish water resources. An industrial scale RO desalination consumes a considerable amount of energy due to the exergy destruction in several units of the process. To mitigate these limitations, several colleagues focused on delivering feasible options to resolve these issues. Most importantly, the intention was to specify the most units responsible for dissipating energy. However, in the literature, no research has been done on the analysis of exergy losses and thermodynamic limitations of the RO system of the Arab Potash Company (APC). Specifically, the RO system of the APC is designed as a medium-sized, multistage, multi pass spiral wound brackish water RO desalination plant with a capacity of 1200 m³/day. Therefore, this paper intends to fill this gap and critically investigate the distribution of exergy destruction by incorporating both physical and chemical exergies of several units and compartments of the RO system. To carry out this study, a sub-model of exergy analysis was collected from the open literature and embedded into the original RO model developed by the authors of this study. The simulation results explored the most sections that cause the highest energy destruction. Specifically, it is confirmed that the major exergy destruction happens in the product stream with 95.8% of the total exergy input. However, the lowest exergy destruction happens in the mixing location of permeate of the first pass of RO desalination system with 62.28% of the total exergy input.

Model Based Simulation and Genetic Algorithm Based Optimisation of Spiral Wound Membrane RO Process for Improved Dimethylphenol Rejection from Wastewater

Reverse Osmosis (RO) has already proved its worth as an efficient treatment method in chemical and environmental engineering applications. Various successful RO attempts for the rejection of organic and highly toxic pollutants from wastewater can be found in the literature over the last decade. Dimethylphenol is classified as a high-toxic organic compound found ubiquitously in wastewater. It poses a real threat to humans and the environment even at low concentration. In this paper, a model based framework was developed for the simulation and optimisation of RO process for the removal of dimethylphenol from wastewater. We incorporated our earlier developed and validated process model into the Species Conserving Genetic Algorithm (SCGA) based optimisation framework to optimise the design and operational parameters of the process. To provide a deeper insight of the process to the readers, the influences of membrane design parameters on dimethylphenol rejection, water recovery rate and the level of specific energy consumption of the process for two different sets of operating conditions are presented first which were achieved via simulation. The membrane parameters taken into consideration include membrane length, width and feed channel height. Finally, a multi-objective function is presented to optimise the membrane design parameters, dimethylphenol rejection and required energy consumption. Simulation results affirmed insignificant and significant impacts of membrane length and width on dimethylphenol rejection and specific energy consumption, respectively. However, these performance indicators are negatively influenced due to increasing the feed channel height. On the other hand, optimisation results generated an optimum removal of dimethylphenol at reduced specific energy consumption for a wide sets of inlet conditions. More importantly, the dimethylphenol rejection increased by around 2.51% to 98.72% compared to ordinary RO module measurements with a saving of around 20.6% of specific energy consumption.

Heat rectification with a minimal model of two harmonic oscillators

We study heat rectification in a minimalistic model composed of two unequal atoms subjected to linear forces and in contact with effective Langevin baths induced by Doppler lasers. Analytic expressions of the heat currents in the steady state are spelled out. Asymmetric heat transport is found in this linear system if both the bath temperatures and the temperature-dependent bath-system couplings are exchanged. The model can be realized with two ions in either common or individual traps. This physical setting allows for a natural temperature dependence of the coupling to the baths. We also explore the parameter space of the model to optimize asymmetric heat current and find conditions for maximal rectification. High rectification corresponds to a good match of the power spectra of the ions for forward temperature bias and mismatch for reverse bias, which may be understood by the behavior of dissipative normal modes.

[Analysis of fatality rates case of SARS-CoV-2 infection in the Autonomous Communities of Spain]

INTRODUCTION

The SARS-CoV-2 pandemic has posed a real challenge to health systems. In Spain, the heterogeneous distribution of the virus infection and the different health strategies have conditioned the morbidity and fatality rate. The aim of this study was to analyse the lethality of the infection by sex and age range in the Autonomous Communities (AC) of Spain.

MATERIAL AND METHODS

To perform the analysis, data were extracted from the Ministry of Health, Regional and Public Health Departments of the different AC. The infected population was estimated from the results of the ENE-COVID19 and the population registered on 1 January 2020 (INE) for the validity of the IgG antibody test with 80% sensitivity and 100% specificity. The case fatality rate (TL) (deaths/1000 estimated infected) by sex and age (<20years, 20-64 and ≥65years) was calculated for each AC. The standardized case fatality ratio (REL) was calculated by the exact method (EPIDAT).

RESULTS

The estimated prevalence of SARS-CoV-2 infection in Spain was 6% (range, 1.4% [Ceuta] -14.1% [Community of Madrid]). The TL in Spain was 9,6/1000, ranged per AC from 1/1000 in Melilla to 26.6/1000 in La Rioja, with no correlation between case fatality and prevalence of infection. The TL was higher in men (10.2/1000, ratio 1.17 with respect to women), except in Cataluña (ratio 0.92), and especially high in those over 64years of age in La Rioja (143.5/1000), Asturias (69.2/1000) and Basque Country (46.6/1000). Overall excess REL was found to be over 30% in La Rioja (2.91; 95%CI: 2.36-3.57), Asturias (1.51; 95%CI: 1.27-1.80), Basque Country (1.42; 95%CI: 1.31-1.54) and Extremadura (1.37; 95%CI: 1.20-1.57) and in those over 64 years in Madrid and the Canary Islands.

CONCLUSIONS

SARs-CoV-2 virus infection has been very unevenly distributed in the different ACs, with notably differences in TL between ACs, particularly high in La Rioja, Asturias and the Basque Country. Is important to study the excess in TL the population over 64years of age in the ACs of Madrid and the Canary Islands.

Hyaluronic acid biomaterial for human tissue-engineered skin substitutes: Preclinical comparative in vivo study of wound healing

BACKGROUND

There is not an ideal biomaterial for tissue-engineered skin substitutes (TESSs), and most of the studies or existing therapies use xenogeneic origin natural biomaterials or biosynthetic scaffolds.

OBJECTIVE

To analyse clinical, histological integration and homeostasis parameters of a human TESS manufactured with fibrin-hyaluronic acid biomaterial (HA-Skin), grafted in immunodeficient mice for 8 weeks, and compared with the gold standard treatment (Autograft), a human TESS manufactured with fibrin-agarose biomaterial (AG-Skin) and secondary wound healing dressings.

METHODS

Human TESSs and autografts were implanted into BALB/c mice after surgical excision. Secondary wound healing approach was achieved with biosynthetic collagen wound dressing (Biobrane^® ) and fibrin-hyaluronic acid or fibrin-agarose biomaterial without cells (Total N = 44). Clinical integration and homeostasis parameters were evaluated every two weeks for two months. Histological and immunohistochemical analyses were performed four and eight weeks after grafting.

RESULTS

HA-Skin, AG-Skin and Autograft groups showed a proper clinical integration and epithelization eight weeks later. Scar evaluation revealed better results for Autograft and HA-Skin. Homeostasis analysis indicated similar values of transepidermal water loss and elasticity between HA-Skin (6.42 ± 0.75 g/h/m² , 0.42 ± 0.08 AU), Autograft (6.91 ± 1.28 g/h/m² , 0.40 ± 0.08 AU) and healthy mouse skin (6.40 ± 0.43 g/h/m² , 0.35 ± 0.03 AU). Histological results showed that human TESSs and autografts presented better skin structuration and higher expression of cytokeratins.

CONCLUSIONS

This study suggests that human TESS based on fibrin-hyaluronic acid biomaterial could be suitable for clinical application in the treatment of several dermatological pathologies (wound healing).

Spatial configurations and temperature profiles in nonequilibrium steady state of two-species trapped ion systems

We study Coulomb crystals containing two ion species simultaneously confined in radio frequency traps and coupled to different thermal reservoirs located in two separate regions. We use a three-dimensional model to simulate the trapped bicrystal and show in a numerically rigorous manner the effects of the mass dependence of the trapping frequencies on the underlying nonequilibrium dynamics and the temperature profiles. By solving the classical Langevin equations of motion, we obtain the spatial probability densities of the two ion species and the kinetic temperature profiles across the axial direction of the trap in the nonequilibrium steady state. We analyze trapping conditions leading to bicrystals that exhibit ion conformations ranging from a linear chain of alternating ion species to two- and three-dimensional configurations. The results evidence the spatial segregation of the two ion species due to the mass dependence of the trapping frequencies and the increase of ion delocalization for heavier ion species and/or weaker trapping confinements. We also show the correlation between the increase of the temperature gradient in the bulk and this enhancement of ion delocalization through the trap.

Delocalization and heat transport in multidimensional trapped ion systems

We study the connection between heat transport properties of systems coupled to different thermal baths in two separate regions and their underlying nonequilibrium dynamics. We consider classical systems of interacting particles that may exhibit a certain degree of delocalization and whose effective dimensionality can be modified through the controlled variation of a global trapping potential. We focus on Coulomb crystals of trapped ions, which offer a versatile playground to shed light on the role that spatial constraints play on heat transport. We use a three-dimensional model to simulate the trapped ion system and show in a numerically rigorous manner to what extent heat transport properties could be feasibly tuned across the structural phase transitions among the linear, planar zigzag, and helical configurations. By solving the classical Langevin equations of motion, we analyze the steady state spatial distributions of the particles, the temperature profiles, and total heat flux through the various structural phase transitions that the system may experience. The results evidence a clear correlation between the degree of delocalization of the internal ions and the emergence of a nonzero gradient in the temperature profiles. The signatures of the phase transitions in the total heat flux as well as the optimal spatial configuration for heat transport are shown.

Correction to: Similarities and differences in tissue distribution of DLK1 and DLK2 during E16.5 mouse embryogenesis

In the original publication of the article, some symbols in Figure 3 were not correctly aligned with the image.

Kinetic modelling of passive transport and active efflux of a fluoroquinolone across Caco-2 cells using a compartmental approach in NONMEM

The purpose was to develop a general mathematical model for estimating passive permeability and efflux transport parameters from in vitro cell culture experiments. The procedure is applicable for linear and non-linear transport of drug with time, <10 or >10% of drug transport, negligible or relevant back flow, and would allow the adequate correction in the case of relevant mass balance problems. A compartmental kinetic approach was used and the transport barriers were described quantitatively in terms of apical and basolateral clearances. The method can be applied when sink conditions are not achieved and it allows the evaluation of the location of the transporter and its binding site. In this work it was possible to demonstrate, from a functional point of view, the higher efflux capacity of the TC7 clone and to identify the apical membrane as the main resistance for the xenobiotic transport. This methodology can be extremely useful as a complementary tool for molecular biology approaches in order to establish meaningful hypotheses about transport mechanisms.

Clinical and polygraphic evolution of sleep-related breathing disorders in adolescents

It has been suggested that sleep-related breathing disorders (SRBD) involve a continuum that develops over the course of life. If modifiable factors could be identified, the progression of SRBD could perhaps be addressed early in life. Although some studies have looked at the evolution of SRBD in pre-pubertal children, very few studies obtained data in adolescents. Anthropometric, clinical and polygraphic variables were collected during a 4-yr follow-up study among 148 normal adolescents after initial cross-sectional analysis. From a total of 267 adolescents studied at baseline (mean+/-sd age 14.3+/-2.1 yrs), 148 (55.4%) were followed up for 4 yrs. During follow-up, there were no significant changes in snoring and polygraphic parameters. However, a tendency toward weight gain with centrally distributed fat was observed. Habitual snorers had a significantly higher body mass index and more centrally distributed fat than nonsnorers. Males had a higher snoring prevalence and a higher number of respiratory events than females. Snoring at baseline, male sex and poor academic performance were significant predictors of snoring at follow-up. Snoring tends to persist during adolescence and male sex acts as a risk factor. A relationship between snoring and academic performance was observed. These findings may have implications for long-term management of sleep-related breathing disorders.

Laboratory evaluation of entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae against puparia and adults of Ceratitis capitata (Diptera: Tephritidae)

Laboratory experiments were done to measure the pathogenicity of 10 autochthonous isolates of Beauveria bassiana (Balsamo) Vuill. and of five Metarhizium anisopliae (Metsch.) Sorok. toward puparia and adults of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Although all isolates applied via inoculation of the fungal suspensions on the ventral surface of the abdomen were pathogenic to adults, with mortality rates ranging from 30 to 100% and average survival times (ASTs) from 6.5 to 8.6 d, when C. capitata puparia were immersed in the conidial suspensions, only B. bassiana Bb-1333 and EABb 01/103-Su and M. anisopliae EAMa 01/58-Su isolates caused >50% mortality of puparia. In a second series of bioassays conducted on five selected isolates, adults were sprayed with four 10-fold concentrations ranging from 1.0 x 10(5) to 1.0 x 10(8) colony-forming units (cfu)/ml. The median lethal concentrations (LC50) of the four most virulent isolates ranged from 4.9 x 10(5) to 2.0 x 10(6) cfu/ml with estimated time to kill 50% of the insects ranging from 4.6 to 5.3 d. The effect of a sublethal dose (ca. LD50) of either B. bassiana EABb 01/103-Su or M. anisopliae EAMa 01/58-Su isolate was studied by reciprocal crossing. Treatment with B. bassiana reduced fecundity and fertility at 6, 8, and 10 d after treatment, with fecundity and fertility reductions ranging from 20.0 to 71.2% and from 33.6 to 60.0%, respectively. These reductions occurred in pairing combinations of treated females with either treated or nontreated males. M. anisopliae was more effective in reducing fecundity and fertility at 6 d after treatment, with the reduction varying from 58.4 to 72.1% and from 28.6 to 45.9%, respectively. In addition, the first oviposition was significantly delayed for 1 d in females treated by either fungal species. The above-mentioned five selected isolates were assayed against C. capitata puparia treated as late third instars in sterilized soil at 25'C under three moisture conditions (-0.1, -0.01, and -0.0055 MPa). At -0.01 MPa, all isolates were low pathogenic to C. capitata puparia, whereas significant differences in the puparia mortality occurred between isolates at -0.1 and -0.0055 MPa. The highest pupal mortalities ranged from 52.5 to 70.0%, as a function of soil moisture and were caused by EAMa 01/58-Su and Bb-1333 isolates.

[Study of unmatched cases and controls: hyperhomocysteinaemia and chronic ischaemic cardiopathy]

OBJECTIVE

To evaluate the extent of the association between hyperhomocysteinaemia and chronic ischaemic heart disease.

DESIGN

Unmatched, case-control (1:3) study.

SETTING

Pintores Health Centre, Area 10, Primary Care, Madrid, Spain.

PARTICIPANTS

Patients of the health centre over 35 with chronic ischaemic heart disease or without it.

METHOD

Consecutive, non-randomized sample. Analysis of cases and controls with chi2 test and odds ratio (OR). The quantitative variables were analysed with the Student's t test.

RESULTS

The 76.32% (87/114) of cases had 2 or more cardiovascular risk factors versus 33.56% (99/265) in the control group (P<.0001). Average homocysteinaemia was 10.07 micromol/L (SD, 3.64) in the control group; and 12.74 (SD, 4.59) in the cases group. The difference between the averages (2.67 micromol/L; 95% CI, 1.82-3.52) was significant (P<.001). The difference (16.07%; 95% CI, 6.91-25.23) in hyperhomocysteinaemia (> or =15 micromol/L) between cases (28.95%, 33/114) and controls (12.88%, 38/295) was significant (P=.0001), with an association between hyperhomocysteinaemia and chronic ischaemic heart disease (OR=2.76; 95% CI, 1.62-4.68). This association increased (OR=3.26; 95% CI, 2.07-5.13) when hyperhomocysteinaemia was taken as > or =12 micromol/L, with a significant difference of 27% (95% CI, 16.59-37.41) (P<.0001) between cases (51.75%, 59/114) and controls (24.75%, 73/295).

CONCLUSIONS

The risk factor of hyperhomocysteinaemia > or =15 micromol/L was significantly associated (OR=2.76) with chronic ischaemic heart disease. This association was greater (OR=3.26) when hyperhomocysteinaemia was taken as > or =12 micromol/L.

Pharmacokinetics, bioavailability and absorption of flumequine in the rat

The study demonstrates that the oral extent of bioavailability of flumequine in the rat, relative to the intravenous injection, is complete (0.94 +/- 0.04) and not significantly different from that found by the intraduodenal route (0.95 +/- 0.04). The rate of oral bioavailability, however, is slow (ka = 1.20 +/- 0.07 h-1; Tmax = 2.0 h), but enough to maintain plasma levels above the minimal inhibitory concentration of the most common pathogens for an extended period of time (about 10 h). The reason for the oral absorption slowness could be a slow gastric emptying, an adsorption to the gastric mucosae, a precipitation in the gastric medium or any other feature concerning the stomach as the intraduodenal administration is very quick (kid = 38.1 +/- 4.7 h-1; Tmax = 0.05 h). A possible precipitation of flumequine cannot be discarded as the solubility of flumequine is very low in the pH range of 3 to 6 (mean pH values for rat stomach and rat intestine, respectively; T.T. Kararli, Biopharm. Drug Dispos. 16 (1995) 351-380). Flumequine was shown to be not substantially excreted in bile (2-3% of the dose). Surprisingly, plasma levels and AUC values found for animals with interrupted bile flow always surpass those found for animals with enterohepatic circulation. This could be due to experimental model features, which might bias plasmatic flumequine concentrations if the homeostatic equilibrium of the animal is not completely restored due to the volume reduction induced by biliary extraction.