The effect of pre-strain on fatigue for a high strength low alloy (HSLA) steel

The effect of initial plastic strain cycle fatigue lives of HSLA specimens is investigated. Specimens were monotonically, quasi-statically loaded under strain control in tension to produce plastic strains (prestrain conditions s0 = 0, s1 = 4,6, s2 = 35,6 and s3 = 66,7 % deformation). Surface analysis on the annealed Zn coat on the prestrain surfaces shows that, the higher the deformation the bigger and deeper the cracks on the Zn coat. Results show that the higher prestrain the higher fatigue resistance for all stress applied, specimens with s3 shows the highest fatigue resistance for these experimental conditions

Effect of cooling rate during solidification on the hard phases of M23C6-type of cast CoCrMo alloy

Microstructural morphology of CoCrMo alloy by control of the cooling rate during the solidification was investigated. Samples were obtained using both an induction furnace for slow cooling rate and electric arc furnace for fast cooling rate. Microstructural characterizations were performed with metallographic techniques. It was found that the difference between the formation temperature of hard secondary phases of M23C6-type carbides determine the reduction of carbide size by increasing the cooling rate

Effect of cooling rate during solidification on the hard phases of M23C6-type of cast CoCrMo alloy

Microstructural morphology of CoCrMo alloy by control of the cooling rate during the solidification was investigated. Samples were obtained using both an induction furnace for slow cooling rate and electric arc furnace for fast cooling rate. Microstructural characterizations were performed with metallographic techniques. It was found that the difference between the formation temperature of hard secondary phases of M23C6-type carbides determine the reduction of carbide size by increasing the cooling rate

Recovery and characterization of a Citrus clementina Hort. ex Tan. 'Clemenules' haploid plant selected to establish the reference whole Citrus genome sequence

<p>Abstract</p> <p>Background</p> <p>In recent years, the development of structural genomics has generated a growing interest in obtaining haploid plants. The use of homozygous lines presents a significant advantage for the accomplishment of sequencing projects. Commercial citrus species are characterized by high heterozygosity, making it difficult to assemble large genome sequences. Thus, the International Citrus Genomic Consortium (ICGC) decided to establish a reference whole citrus genome sequence from a homozygous plant. Due to the existence of important molecular resources and previous success in obtaining haploid clementine plants, haploid clementine was selected as the target for the implementation of the reference whole genome citrus sequence.</p> <p>Results</p> <p>To obtain haploid clementine lines we used the technique of <it>in situ </it>gynogenesis induced by irradiated pollen. Flow cytometry, chromosome counts and SSR marker (Simple Sequence Repeats) analysis facilitated the identification of six different haploid lines (2<it>n </it>= <it>x </it>= 9), one aneuploid line (2<it>n </it>= 2<it>x</it>+4 = 22) and one doubled haploid plant (2<it>n </it>= 2<it>x </it>= 18) of 'Clemenules' clementine. One of the haploids, obtained directly from an original haploid embryo, grew vigorously and produced flowers after four years. This is the first haploid plant of clementine that has bloomed and we have, for the first time, characterized the histology of haploid and diploid flowers of clementine. Additionally a double haploid plant was obtained spontaneously from this haploid line.</p> <p>Conclusion</p> <p>The first haploid plant of 'Clemenules' clementine produced directly by germination of a haploid embryo, which grew vigorously and produced flowers, has been obtained in this work. This haploid line has been selected and it is being used by the ICGC to establish the reference sequence of the nuclear genome of citrus.</p

La influencia del darwinismo sobre los conceptos raciales en México

It has been repeatedly pointed out that Vicente Riva Palacio and Andrés Molina Enríquez were influenced by Darwin’s ideas to develop their own racial concepts regarding the Mexican half-blood. However, after analysing said ideas both in their original biological context as in the social context they were transferred to, it is concluded that this affirmation can only be accepted sensu lato. Their thesis about the superiority of the half-blood is more strongly based on lineal conceptions of evolution and their own alterations than in the Darwinist model of natural selection. It is important to know the influence of Darwinism outside its original context as it helps to understand how the complex and unavoidable exchanges among science, society and politics occurred. Their appropriation of the Darwinist ideas may not be conceptually or methodologically accurate, but it contributed to the ideological construction of the half-blood as an advanced race in terms of evolution. This thesis contrasts with the most prevailing one in other Latin American countries, where the half-bloods were perceived as the personification of a racial degeneration.Se ha señalado reiteradamente que Vicente Riva Palacio y Andrés Molina Enríquez fueron influidos por las ideas de Darwin al desarrollar sus propios conceptos raciales sobre el mestizo mexicano. Sin embargo, después de analizar dichas ideas tanto en su contexto biológico original como en el ámbito social al que fueron trasplantadas, concluimos que tal afirmación solo puede aceptarse en un sentido laxo. Su tesis sobre la superioridad del mestizo se sustentó más en concepciones lineales de la evolución y en mixtificaciones propias que en el modelo darwinista de selección natural. Conocer las repercusiones del darwinismo fuera de su ámbito original contribuye a entender cómo se dio el complejo e inevitable interjuego entre ciencia, sociedad y política. Aunque la apropiación que hicieron Riva Palacio y Molina de las ideas darwinistas no tuvo rigor conceptual ni metodológico, contribuyó a la construcción ideológica del mestizo como una raza evolutivamente avanzada. Esta tesis contrasta con la que prevaleció en otros países latinoamericanos, donde se concibió al mestizo como la personificación de la degeneración racial

Pharmaceuticals and environmental risk assessment in municipal wastewater treatment plants and rivers from Peru

This is the first study dealing with removal of the pharmaceutical substances in municipal wastewater treatment plants (MWWTPs) from Peru and the impact of these compounds in surface waters receiving treated wastewater. To this aim, samples from MWWTP of Lima (Peruvian Coast), MWWTP of Cusco, Puno and Juliaca (Peruvian Highlands), as well surface water (confluence of Torococha and Coata rivers in Juliaca) were analyzed. A total of 38 target pharmaceuticals were included in this study and were determined by Liquid Chromatography coupled to tandem Mass Spectrometry (LC-MS/MS). Around 60% and 75% of the target pharmaceuticals could be quantified in surface water and MWWTPs, respectively. Acetaminophen was the drug found at the highest concentration, and it was present in all the treated wastewater samples reaching average values above 100 μg/L in the department of Puno. The gabapentin anti-epileptic drug (up to 11.85 μg/L in MWWTP Lima) and the antibiotics clarithromycin, trimethoprim, ciprofloxacin, sulfamethoxazole and azithromycin (1.86 to 4.47 μg/L in MWWTP Lima) were also found at moderate concentrations in the treated wastewater. In surface water, the highest concentration corresponded also to acetaminophen (28.70 μg/L) followed by sulfamethoxazole (4.36 μg/L). As regards the pharmaceuticals removal, data of this work showed that the MWWTP Cusco (aerobic biologic process by synthetic trickling filters as secondary treatment) was more efficient than the MWWTP Lima (a preliminary treatment that combines grilles, sand trap, degreaser-aerated and sieved of 1.0 mm). However, many pharmaceuticals (around 50% of the compounds investigated) presented concentrations in treated wastewater similar or even higher than in influent wastewater. The environmental ecological risk of pharmaceuticals was assessed based on calculated Risk Quotient (RQ) in the treated wastewater and surface water from the concentration data found in the samples. According to our data, three antibiotics (clarithromycin, ciprofloxacin, clindamycin) and the analgesic acetaminophen posed high environmental risk (RQ ≥ 1) on the aquatic environment. In the river, all antibiotics (except norfloxacin) as well as the analgesic-anti-inflammatory compounds acetaminophen, diclofenac posed a high environmental risk (RQ ≥ 1). Based on data reported in this work for the first time in water samples from Peru, it can be deduced that the treatment processes applied in important cities from Peru are not enough efficient to remove pharmaceuticals in wastewater. As a consequence, severe environmental risks associated to the presence of pharmaceuticals in treated wastewater and surface water are expected; so complementary treatment processes should be implemented in the MWWTPs for a more efficient elimination of these compounds