A method to assess the quality of additive manufacturing metal powders using the triboelectric charging concept.

A new method to assess the quality of additive manufacturing (AM) metal powders using the triboelectric charging concept is demonstrated using CpTi, Ti6Al4V, AlSi10Mg, IN 738, and SS 316L powders. For each powder tested, the surface chemical composition was first analyzed using X-ray photoelectron spectroscopy (XPS) to determine the composition of the passivation layer. Some modifications to the current GranuCharge™ setup, developed by GranuTools™, were then performed by incorporating a flow rate measuring tool to assess how tribocharging is affected as a function of flow rate. Variations in the tribocharging response have been found with the flow rate of CpTi, AlSi10Mg and SS 316L powders. Moreover, results suggest that the tribocharging behavior might not be the same even with powders fabricated with the same passivation process. Finally, the compressed exponential model of Trachenko and Zaccone was used to reproduce the tribocharging behavior of the powders. The models were found to work best when the stretch constant ß = 1.5, which is identical to the value found in other systems such as structural glasses, colloidal gels, entangled polymers, and supercooled liquids, which experience jamming when motion of individual particles become restricted, causing their motion to slow down.

Development of Ti-Al-V alloys for usage as single-axis knee prostheses: evaluation of mechanical, corrosion, and tribocorrosion behaviors.

Single-axis knee prosthesis is an artificial biomechanical device that provides motion to amputees without the need for assistance appliances. Besides it is mainly composed of metallic materials, the current commercial materials did not group adequate properties for long-term usage or accessible cost. This study produced and characterized Ti-(10 -x)Al-xV (x = 0, 2, and 4 wt.%) alloys for potential use as single-axis knee prostheses. The samples exhibited a gradual decrease in the density values, with proper chemical mixing of the alloying elements on the micro-scale. The phase composition exhibited a primary α phase with a minor α' + ß phase for the Ti-8Al-2V and Ti-6Al-4V samples. Due to their different atomic radius compared to Ti, the addition of alloying elements changed the cell parameters. Their selected mechanical properties (Young's modulus, Vickers microhardness, and damping factor) performed better values than the CP-Ti grade 4. The samples also exhibited good corrosion properties against the simulated marine solution. The tribocorrosion resistance of the samples was better than the reference material, with the wear tracks composed of some tribolayers and grooves resulting from adhesive and abrasive wear. The Ti-10Al alloy displayed the best properties and estimated low cost to be used as single-axis knee prostheses.

Diagnóstico de malformación uterina en una paciente de 10 años con piometra. A propósito de un caso / Diagnosis of uterine malformation in a ten-year-old patient. Case report

Las malformaciones uterinas congénitas son poco frecuentes. El útero bicorporal tiene una prevalencia del 0,4%. Generalmente asintomático, se puede manifestar como dolor pélvico por un hematometra o menstruación retrógrada de un cuerno uterino no comunicante. Se presenta el caso de una niña de 10 años a quien, en el contexto de dolor abdominal y fiebre, se le realizaron pruebas de imagen y en quien se objetivó un útero bicorporal ocupado por lo que parecía un hematometra. Se intervino a la paciente para drenarlo, por vía histeroscópica y laparoscópica, y se comprobó que se trataba de un piometra. Se realizó hemihisterectomía, sin incidencias, con el fin de preservar su fertilidad y resolver el cuadro infeccioso.(AU)

Congenital uterine malformations are rare. The bicorporal uterus has a prevalence of 0.4%. Generally asymptomatic, it can manifest as pelvic pain from a haematometra or retrograde menstruation from a non-communicating uterine horn. The case of a 10-year-old girl is presented who, in the context of abdominal pain and fever, underwent imaging tests revealing a bicornuate uterus occupied by what appeared to be a haematometra. The patient was operated on to drain it, hysteroscopically and laparoscopically, confirming that it was a pyometra. Hemihysterectomy was performed without incident to preserve fertility and resolve the infection.(AU)

Oxygen uptake rate in alginate producer (algU+) and nonproducer (algU-) strains of Azotobacter vinelandii under nitrogen-fixation conditions.

AIMS: The sigma E (AlgU) in Azotobacter vinelandii has been shown to control the expression of cydR gene, a repressor of genes of the alternative respiratory chain, and alginate has been considered a barrier for oxygen diffusion. Therefore, the aim of the present study was to compare the respiratory activity of an alginate nonproducing strain, lacking the sigma factor E (algU-), and polymer-producing strains (algU+) of A. vinelandii under diazotrophic conditions at different aeration conditions. METHODS AND RESULTS: Our results reveal that under diazotrophic and high aeration conditions, A. vinelandii strain OP (algU-) had a specific oxygen consumption rate higher (30 and 54%) than those observed in the OP algU+-complemented strain, named OPAlgU+, and the ATCC 9046 respectively. However, the specific growth rate and biomass yields (based on oxygen and sucrose) were lower for OP cultivations as compared to the algU+ strains. These differences were partially explained by an increase in 1·5-fold of cydA relative expression in the OP strain, as compared to that obtained in the isogenic OPAlgU+ strain. CONCLUSIONS: Overall, our results confirm the important role of algU gene on the regulation of respiratory metabolism under diazotrophic growth when A. vinelandii is exposed to high aeration. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights the role of AlgU to control respiration of A. vinelandii when exposed to diazotrophy.

Wheezing and risk factors in the first year of life in Cantabria, Spain. The EISL study

OBJECTIVES: To determine the prevalence of wheezing during the first year of life in Cantabria, Spain and its associated risk factors. METHODOLOGY: A cross-sectional, multicentre, descriptive epidemiological study was carried out in a representative sample of 958 infants in the first year of life, born in Cantabria. A previously validated and standardised written questionnaire was completed by the parents of infants seen between 12 and 15 months of age in the Primary Care Centres. RESULTS: The prevalence of wheezing was 32.7%. A relationship was found with male gender (OR 1.38, 95%CI [1.05-1.81]), the presence of a sibling (OR 2.43 [1.38-3.98]), attending nursery school (OR 2.40 [1.71-3.35]), exclusive breastfeeding for <3 months (OR 1.47 [1.12-1.93]), a first cold at ≤3 months (OR 2.07 [1.56-2.74]), asthma in siblings (OR 2.17 [1.25-3.77]), parental allergic rhinitis (OR 1.62 [1.10-2.37]) and paracetamol use >1 a week (OR 2.49 [1.31-4.73]), and maternal smoking during pregnancy (OR 2.18 [1.51-3.15]). The prevalence of recurrent wheezing (≥3 episodes) was 14.3%. Significant associations were observed with the male gender (OR 1.79 [1.23-2.60]), attending nursery school (OR 2.92 [1.96-4.35]), first cold at ≤3 months (OR 2.11 [1.46-3.04]), eczema (OR 1.92 [1.21-3.04]), maternal asthma (OR 1.77 [1.00-3.14]), exclusive breastfeeding for <3 months (OR 1.53 [1.06-2.22]), and maternal smoking during pregnancy (OR 1.53 [1.05-2.22]). CONCLUSIONS: One third of the infants experienced wheezing during the first year of life; those who were less exclusively breastfed, attended nursery school, presented eczema, family asthma or allergic rhinitis, and maternal smoking during pregnancy

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Intense pulsed light induces synthesis of dermal extracellular proteins in vitro.

Intense pulsed light (IPL) devices have been shown to be highly effective for the skin rejuvenation. In our study, we try to elucidate effects of IPL in fibroblast proliferation, in gene expression, and in extracellular matrix protein production. 1BR3G human skin fibroblasts were used to test the effects of an IPL device (MiniSilk FT, Deka®). Fibroblasts were divided into three groups: group 1 was irradiated with filter 800-1200 nm (frequency 10 Hz, 15 s, fluence 60.1 J/cm) twice; group 2 was irradiated with filter 550-1200 nm (double pulse 5 ms + 5 ms, delay 10 ms, fluence 13 J/cm2) twice; and group 3 was irradiated with filter 550-1200 nm (frequency 10 Hz, 15 s, fluence 60.1 J/cm2) twice. To determine changes in gene expression, messenger RNA (mRNA) levels for collagen types I and III and metalloproteinase 1 (MMP-1) were performed 48 h after irradiation. To determine changes in hyaluronic acid, versican, and decorin, mRNA and ELISA tests were performed after 48 h of treatment. In addition to this, a Picro-Sirius red staining for collagen was made. The study showed an increase of mRNA and hyaluronic acid, decorin, and versican production. With RT-PCR assays, an increase mRNA for collagen type I, type III, and MMP-1 was observed. Collagen and hyaluronic synthesis was increased in all groups with no differences among them, while decorin and versican synthesis was higher in those groups irradiated with 550-1200-nm filters with no dependence of type pulse or total energy dose. IPL applied in vitro cultured cells increases fibroblasts activity. Synthesis of extracellular proteins seems to be produced more specifically in determined wavelengths, which could demonstrate a biochemical mechanism light depending.

Wheezing and risk factors in the first year of life in Cantabria, Spain. The EISL study.

OBJECTIVES: To determine the prevalence of wheezing during the first year of life in Cantabria, Spain and its associated risk factors. METHODOLOGY: A cross-sectional, multicentre, descriptive epidemiological study was carried out in a representative sample of 958 infants in the first year of life, born in Cantabria. A previously validated and standardised written questionnaire was completed by the parents of infants seen between 12 and 15 months of age in the Primary Care Centres. RESULTS: The prevalence of wheezing was 32.7%. A relationship was found with male gender (OR 1.38, 95%CI [1.05-1.81]), the presence of a sibling (OR 2.43 [1.38-3.98]), attending nursery school (OR 2.40 [1.71-3.35]), exclusive breastfeeding for <3 months (OR 1.47 [1.12-1.93]), a first cold at ≤3 months (OR 2.07 [1.56-2.74]), asthma in siblings (OR 2.17 [1.25-3.77]), parental allergic rhinitis (OR 1.62 [1.10-2.37]) and paracetamol use >1 a week (OR 2.49 [1.31-4.73]), and maternal smoking during pregnancy (OR 2.18 [1.51-3.15]). The prevalence of recurrent wheezing (≥3 episodes) was 14.3%. Significant associations were observed with the male gender (OR 1.79 [1.23-2.60]), attending nursery school (OR 2.92 [1.96-4.35]), first cold at ≤3 months (OR 2.11 [1.46-3.04]), eczema (OR 1.92 [1.21-3.04]), maternal asthma (OR 1.77 [1.00-3.14]), exclusive breastfeeding for <3 months (OR 1.53 [1.06-2.22]), and maternal smoking during pregnancy (OR 1.53 [1.05-2.22]). CONCLUSIONS: One third of the infants experienced wheezing during the first year of life; those who were less exclusively breastfed, attended nursery school, presented eczema, family asthma or allergic rhinitis, and maternal smoking during pregnancy.

Hydrodynamics, Fungal Physiology, and Morphology.

Filamentous cultures, such as fungi and actinomycetes, contribute substantially to the pharmaceutical industry and to enzyme production, with an annual market of about 6 billion dollars. In mechanically stirred reactors, most frequently used in fermentation industry, microbial growth and metabolite productivity depend on complex interactions between hydrodynamics, oxygen transfer, and mycelial morphology. The dissipation of energy through mechanically stirring devices, either flasks or tanks, impacts both microbial growth through shearing forces on the cells and the transfer of mass and energy, improving the contact between phases (i.e., air bubbles and microorganisms) but also causing damage to the cells at high energy dissipation rates. Mechanical-induced signaling in the cells triggers the molecular responses to shear stress; however, the complete mechanism is not known. Volumetric power input and, more importantly, the energy dissipation/circulation function are the main parameters determining mycelial size, a phenomenon that can be explained by the interaction of mycelial aggregates and Kolmogorov eddies. The use of microparticles in fungal cultures is also a strategy to increase process productivity and reproducibility by controlling fungal morphology. In order to rigorously study the effects of hydrodynamics on the physiology of fungal microorganisms, it is necessary to rule out the possible associated effects of dissolved oxygen, something which has been reported scarcely. At the other hand, the processes of phase dispersion (including the suspended solid that is the filamentous biomass) are crucial in order to get an integral knowledge about biological and physicochemical interactions within the bioreactor. Digital image analysis is a powerful tool for getting relevant information in order to establish the mechanisms of mass transfer as well as to evaluate the viability of the mycelia. This review focuses on (a) the main characteristics of the two most common morphologies exhibited by filamentous microorganisms; (b) how hydrodynamic conditions affect morphology and physiology in filamentous cultures; and (c) techniques using digital image analysis to characterize the viability of filamentous microorganisms and mass transfer in multiphase dispersions. Representative case studies of fungi (Trichoderma harzianum and Pleurotus ostreatus) exhibiting different typical morphologies (disperse mycelia and pellets) are discussed.

Characterization of the dengue outbreak in Nuevo Leon state, Mexico, 2010.

We studied serotypes circulating dengue virus (DENV) cases, entomological Breteau index, rain-fall index and epidemiology of groups affected during the 2010 outbreak in Nuevo Leon, Mexico. From 2,271 positive cases, 94% were dengue classic and 6% dengue hemorrhagic fever; DENV1 was mainly isolated (99%) (Central-American lineage of American-African-genotype). We found correlation between two environmental phenomena (Increment of rainfall and vector-indexes) (p ≤ 0.05) with epidemiological, clinical and risk of DENV-1 ongoing transmission.

Increased fibroblast proliferation and activity after applying intense pulsed light 800-1200 nm.

BACKGROUND AND OBJECTIVES: Light devices emitting near infrared have been shown to be highly effective for the skin rejuvenation but biochemical and molecular mechanism or optimum dose treatment are not well-known. In our study we try to elucidate why systems emitting near infrared produce skin improvement such as fibroblasts proliferation, increase in gene expression or extracellular matrix (ECM) protein production. STUDY DESIGN/MATERIALS AND METHODS: 1BR3G human skin fibroblasts were used to test the effects of an intense pulsed light device emitting with an 800-1200 nm filter (MiniSilk FT manufactured by Deka(®)). In our protocol, fibroblasts were irradiated twice successively with a 10 Hz frequency, with a total fluence up to 60 J/cm(2) for 15s each pass. After incubating for 48 h, fibroblasts were harvested from the culture plates to test cell proliferation by flow cytometer. To determine changes in gene expression (mRNA levels for collagen types I and III and metalloproteinase 1 (MMP-1)) and protein production (hyaluronic acid, versican and decorin) tests were performed after irradiation. RESULTS: After 48 h irradiation, 1BR3G human skin fibroblasts were observed to proliferate at a fast rate. The study of ECM macromolecules production using ELISA showed an increase of hyaluronic acid and versican production but no changes were observed for decorin. With RT-PCR assays, an increase in mRNA for collagen type I, type III and MMP-1 were observed. CONCLUSION: Intense pulsed light emitting near infrared applied in vitro cultured cells increases fibroblasts proliferation and activity, which can be a possible mechanism of action for these devices in aging skin treatment.

La sífilis y la experimentación en humanos: perspectiva histórica y reflexiones éticas. De la Segunda Guerra Mundial a la actualidad / Syphilis and Human Experimentation From World War II to the Present: A Historical Perspective and Reflections on Ethics

Incluso después de la promulgación del código de Nuremberg las investigaciones sobre sífilis continuaron alejándose en muchas ocasiones de los estándares éticos. En este artículo hemos revisado las investigaciones que sobre esta enfermedad tuvieron lugar después de la Segunda Guerra Mundial, centrándonos en los casos de Guatemala y de Tuskegee. En Guatemala durante los a˜nos 1946 a 1948 se inoculó deliberadamente a más de 1.000 adultos sífilis, cancroide y gonorrea, y se hicieron miles de serologías a poblaciones indígenas o a ni˜nos huérfanos. El experimento Tuskegee sobre sífilis fue realizado entre 1932 y 1972 por el Servicio Público de Salud de los Estados Unidos para estudiar la evolución natural de esta enfermedad en ausencia de tratamiento. Se realizó sobre un grupo de población rural de raza negra y no se interrumpió a pesar de la introducción de tratamientos eficaces para la resolución de la enfermedad durante estos años (1945)

Even after the Nuremberg code was published, research on syphilis often continued to fall far short of ethical standards. We review post-World War II research on this disease, focusing on the work carried out in Guatemala and Tuskegee. Over a thousand adults were deliberately inoculated with infectious material for syphilis, hancroid, and gonorrhea between 1946 and 1948 in Guatemala, and thousands of serologies were performed in individuals belonging to indigenous populations or sheltered in orphanages. The Tuskegee syphilis study, conducted by the US Public Health Service, took place between 1932 and 1972 with the aim of following the natural history of the disease when left untreated. The subjects belonged to a rural black population and the study was not halted when effective treatment for syphilis became available in 1945

Experimentación en sífilis hasta la Segunda Guerra Mundial: historia y reflexiones éticas / Syphilis and Human Experimentation From the First Appearance of the Disease to World War II: A Historical Perspective and Reflections on Ethics

Durante siglos la sífilis ha sido objeto de investigación por parte de los médicos, dado que la etiología, la forma de contagio, la profilaxis y el tratamiento eran desconocidos. En muchas ocasiones las investigaciones se han alejado de los estándares éticos actuales. En este artículo hemos revisado desde un punto de vista histórico y ético las investigaciones que sobre esta enfermedad se han ido realizando a lo largo de los siglos, centrándonos sobre todo en aquellos experimentos realizados en el siglo XX. Describimos con detalle los estudios realizados en los años que tuvieron lugar alrededor de la Segunda Guerra Mundial: experimentos realizados por los médicos norteamericanos en prisiones de Estados Unidos, la sífilis en la Alemania nazi o los ensayos realizados por los japoneses en centros de experimentación creados a tal fin en los territorios ocupados

Physicians have conducted research on syphilis for centuries, seeking to understand its etiology and the means of transmission as well as find ways to prevent and cure the disease. Their research practices often strayed from today's ethical standards. In this paper we review ethical aspects of the long history of research on syphilis with emphasis on the experiments performed in the 20th century. The description of research around the time of World War II covers medical experiments carried out in US prisons and in the experimentation centers established by Japanese doctors in occupied territory, as well as experiments in Nazi Germany and the treatment of syphilitics there

Syphilis and human experimentation from World War II to the present: a historical perspective and reflections on ethics.

Even after the Nuremberg code was published, research on syphilis often continued to fall far short of ethical standards. We review post-World War II research on this disease, focusing on the work carried out in Guatemala and Tuskegee. Over a thousand adults were deliberately inoculated with infectious material for syphilis, chancroid, and gonorrhea between 1946 and 1948 in Guatemala, and thousands of serologies were performed in individuals belonging to indigenous populations or sheltered in orphanages. The Tuskegee syphilis study, conducted by the US Public Health Service, took place between 1932 and 1972 with the aim of following the natural history of the disease when left untreated. The subjects belonged to a rural black population and the study was not halted when effective treatment for syphilis became available in 1945.

On the effects of the dispersant Corexit 9500© during the degradation process of n-alkanes and PAHs in marine sediments.

In many coastal countries, oil spill contingency plans include several alternatives for removal of the spilled oil from the ocean. Frequently, these plans include dispersants. Because this process applies chemical substances that may add toxicity to oil that already contains toxic compounds, it is, at times, a controversial method to fight oil pollution. Additionally, local conditions may result in particular complications. We investigated the possible effects of the dispersant Corexit 9500© under conditions similar to those of subtropical oceans. We used fuel oil #6+ diesel as the test mixture. Under certain conditions, at least part of the dispersed oil may reach the sediment, particularly if the dispersant is applied in coastal waters. Nine experimental units were used in this experiment. Similar conditions of water temperature, salinity, air fluxes into the experimental units, and hydrocarbon concentrations in sediments were used. Two treatments and one control, each one with three replicates, were carried out. We concentrated our investigation on sediment, although measurements of water were also taken. Our results suggest that once the oil has penetrated the sediment, no significant differences exist between oil that contains dispersant and oil without dispersant. Noticeable degradation of aliphatic hydrocarbons occurred mainly in the low molecular weight aliphatic hydrocarbons and not in the others. Apparently, degradation of aromatics was easier than that of alkanes. However, some differences were noticed for the degradation of PAHs in the sediment, suggesting a faster degradation under particular conditions in aerobic environments such as under this experiment.

Syphilis and human experimentation from the first appearance of the disease to World War II: a historical perspective and reflections on ethics.

Physicians have conducted research on syphilis for centuries, seeking to understand its etiology and the means of transmission as well as find ways to prevent and cure the disease. Their research practices often strayed from today's ethical standards. In this paper we review ethical aspects of the long history of research on syphilis with emphasis on the experiments performed in the 20th century. The description of research around the time of World War II covers medical experiments carried out in US prisons and in the experimentation centers established by Japanese doctors in occupied territory, as well as experiments in Nazi Germany and the treatment of syphilitics there.

Study of wheezing and its risk factors in the first year of life in the Province of Salamanca, Spain. The EISL Study

Objectives: To determine the prevalence of wheezing and its associated risk factors in infants in the first year of life in the province of Salamanca, Spain. Methods: A multicentre, cross-sectional, descriptive epidemiological study was designed to evaluate a representative sample of 750 infants in the first year of life, born in the province of Salamanca between 1 June 2008 and 30 September 2009.The study was based on a previously validated and standardised written questionnaire administered among the parents of those children seen for control at 12 months of age in any of the Primary Care centres in the province of Salamanca. Results: The recorded wheezing rate was 32.3%. Feeding and sleep were seen to be affected in 46.3% and 80.9% of the wheezing children, respectively, and parent activity was also altered in 39.3% of the cases. A relationship was found between wheezing and nursery attendance (OR: 1.66, 95% confidence interval [1.19-2.31]); weight at birth >3500g (OR: 1.45 [1.02-2.06]); the presence of eczema at this age (OR: 2.72 [1.75-4.24]); exclusive breastfeeding for <3 months (OR: 1.33 [0.98-1.81]); and maternal smoking during the last three months of pregnancy (OR: 1.60 [0.96-2.68]).The prevalence of recurrent wheezing (defined as three or more episodes) was 11.9%. Significant differences were observed with respect to nursery attendance (OR: 1.71 [1.08-2.72]), the presence of eczema at this age (OR: 2.55 [1.48-4.42]), a history of maternal asthma (OR: 2.19 [1.08-4.44]) and exclusive breastfeeding for <3 months (OR: 1.53 [0.98-2.38]). Conclusions: In the province of Salamanca, one third of the infants studied suffered wheezing in the first year of life. Infants exclusively breastfed for less than three months; attending a nursery; having suffered eczema; or with an asthmatic mother showed significantly more wheezing than the rest. Wheezing proved recurrent in 11.9% of the cases(AU)

Study of wheezing and its risk factors in the first year of life in the Province of Salamanca, Spain. The EISL Study.

OBJECTIVES: To determine the prevalence of wheezing and its associated risk factors in infants in the first year of life in the province of Salamanca, Spain. METHODS: A multicentre, cross-sectional, descriptive epidemiological study was designed to evaluate a representative sample of 750 infants in the first year of life, born in the province of Salamanca between 1 June 2008 and 30 September 2009. The study was based on a previously validated and standardised written questionnaire administered among the parents of those children seen for control at 12 months of age in any of the Primary Care centres in the province of Salamanca. RESULTS: The recorded wheezing rate was 32.3%. Feeding and sleep were seen to be affected in 46.3% and 80.9% of the wheezing children, respectively, and parent activity was also altered in 39.3% of the cases. A relationship was found between wheezing and nursery attendance (OR: 1.66, 95% confidence interval [1.19-2.31]); weight at birth >3500 g (OR: 1.45 [1.02-2.06]); the presence of eczema at this age (OR: 2.72 [1.75-4.24]); exclusive breastfeeding for <3 months (OR: 1.33 [0.98-1.81]); and maternal smoking during the last three months of pregnancy (OR: 1.60 [0.96-2.68]). The prevalence of recurrent wheezing (defined as three or more episodes) was 11.9%. Significant differences were observed with respect to nursery attendance (OR: 1.71 [1.08-2.72]), the presence of eczema at this age (OR: 2.55 [1.48-4.42]), a history of maternal asthma (OR: 2.19 [1.08-4.44]) and exclusive breastfeeding for <3 months (OR: 1.53 [0.98-2.38]). CONCLUSIONS: In the province of Salamanca, one third of the infants studied suffered wheezing in the first year of life. Infants exclusively breastfed for less than three months; attending a nursery; having suffered eczema; or with an asthmatic mother showed significantly more wheezing than the rest. Wheezing proved recurrent in 11.9% of the cases.

Relationship between metal enrichments and a biological adverse effects index in sediments from Todos Santos Bay, northwest coast of Baja California, México.

In 1992 and 2004, heavy metals concentrations were measured in surficial sediments from Todos Santos Bay, located in Ensenada, Baja California, Mexico. The aim was to search for relationships between metal enrichment factors and a biological adverse effects index. Unlike Ni, the elements Cd, Cu and Zn showed significant correlations (p<0.05) between enrichment factors and the biological adverse effects index. Cu showed a 0.74:1 relationship, which means that any enrichment above 0.74 could represent biological adverse effects. On the other hand, Cd and Zn enrichments must be >5.5 and >1.5, respectively, in order for the sediments to be considered toxic. In general, data showed that most of the metal concentrations in Todos Santos Bay sediments could not cause adverse effects to biota. Only Ensenada's harbor and the zone next to a dredging dumping site showed metal enrichments that could be toxic.

Distribution of selenium, molybdenum and uranium in sediment cores from the Colorado River delta, Baja California, Mexico.

The distribution of selenium, molybdenum and uranium was studied in ~1.5 m sediment cores from the Colorado River delta, at the Colorado (CR) and Hardy (HR) riverbeds. Core HR2 showed highest Se, Mo and U concentrations at its bottom (2.3, 0.95 and 1.8 µg g(-1)) within a sandy-silt layer deposited prior to dam construction. In CR5 the highest concentrations of these elements (0.9, 1.4 and 1.7 µg g(-1) respectively) were located at the top of the core within a surface layer enriched in organic carbon. A few samples from HR2 had Se above the probable toxic effect level guidelines.