Machinability of INCONEL718 Alloy with a Porous Microstructure Produced by Laser Melting Powder Bed Fusion at Higher Energy Densities

Products produced by additive manufacturing (AM) seek to exploit net shape manufacturing by eliminating or minimizing post-process stages such as machining. However, many applications which include turbo machinery components with tight dimensional tolerances and a smooth surface finish will require at least a light machine finishing stage. This paper investigates the machinability of the additively fabricated INCONEL718 (IN718) alloy produced by laser melting powder bed fusion (LM-PBF) with different levels of spherical porosity in the microstructure. The literature suggests that the band width for laser energy density, which combines the various scan process parameters to obtain a low spherical type porosity in the LM-PBF IN718 alloy (~1%), has wide breadth. With the increasing laser energy density and above a threshold, there is a rapid increase in the spherical pore size. In this paper, three tube samples each with different levels of spherical porosity were fabricated by varying the laser energy density for LM-PBF of the IN718 alloy within the stable and higher energy density range and the porosity measured. A low laser energy density was avoided due to balling up, which promotes highly irregular lack of fusion defects and poor consolidation within the alloy microstructure. An orthogonal turning test instrumented, with a three-component dynamometer to measure the cutting forces, was performed on AM produced IN718 tube samples under light cut conditions to simulate a finish machining process. The orthogonal turning tests were also performed on a tube sample obtained from the wrought extruded stock. The machining process parameters, which were studied include varying the cutting speed at three levels, at a fixed feed and under dry cut conditions for a short duration to avoid the tool wear. The results obtained were discussed and a notable finding was the higher rate of built-up-edge formation on the tool tip from the AM samples with a higher porosity and especially at a higher cutting speed. The paper also discusses the mechanisms that underpin the findings.     

Patrón de inicio del seguimiento clínico en los pacientes con infección por el virus de la inmunodeficiencia humana en España

Objetive

To describe linkage to care among new HIV diagnoses in Spain; and to estimate factors associated to linkage to care within three months after diagnosis.

Methods

The distribution of the time elapsing between the date of HIV diagnosis and the date of first determination of CD4 (considered to be the date of linkage to care) was calculated among new HIV diagnoses in 2010 in the seven Autonomous Regions participating, where data on date of CD4 count was available. Linkage to care was considered «correct» if done within three months after diagnosis. Factors associated to correct linkage to care were estimated using logistic regression.

Results

A total of 1769 new HIV diagnoses were included. Of them, 83.1% had evidence of linkage to care within a year, and 75.7% were linked within three months after diagnosis. Being an injectable drug user (IDU) was the only factor inversely associated with linkage to care within 3 months (OR = 0.3; 95% CI: 0.2-0.6).

Conclusion

In Spain linkage to care after HIV diagnosis is good, but there is still room for improvement, especially among IDUs.     

Implications of Lipids in Neonatal Body Weight and Fat Mass in Gestational Diabetic Mothers and Non-Diabetic Controls

Purpose of Review

Maternal lipid metabolism greatly changes during pregnancy and we review in this article how they influence fetal adiposity and growth under non-diabetic and gestational diabetic conditions.

Recent Findings

In pregnant women without diabetes (control), maternal glycemia correlates with neonatal glycemia, neonatal body weight and fat mass. In pregnant women with gestational diabetes mellitus (GDM), maternal glucose correlates with neither neonatal glycemia, neonatal birth weight nor fat mass, but maternal triacylglycerols (TAG), non-esterified fatty acids (NEFA) and glycerol do correlate with birth weight and neonatal adiposity. The proportions of maternal plasma arachidonic (AA) and docosahexaenoic (DHA) acids decrease from the first to the third trimester of pregnancy, and at term these long-chain polyunsaturated fatty acids are higher in cord blood plasma than in mothers, indicating efficient placental transfer. In control or pregnant women with GDM at term, the maternal concentration of individual fatty acids does not correlate with neonatal body weight or fat mass, but cord blood fatty acid levels correlate with birth weight and neonatal adiposity—positively in controls, but negatively in GDM. The proportion of AA and DHA in umbilical artery plasma in GDM is lower than in controls but not in umbilical vein plasma. Therefore, an increased utilization of those two fatty acids by fetal tissues, rather than impaired placental transfer, is responsible for their smaller proportion in plasma of GDM newborns.

Summary

In control pregnant women, maternal glycemia controls neonatal body weight and fat mass, whereas in mothers with GDM—even with good glycemic control—maternal lipids and their greater utilization by the fetus play a critical role in neonatal body weight and fat mass. We propose that altered lipid metabolism rather than hyperglycemia constitutes a risk for macrosomia in GDM.

     

Deciphering the role of IS6110 in a highly transmissible Mycobacterium tuberculosis Beijing strain, GC1237

The capacity of infection and the ability of Mycobacterium tuberculosis strains belonging to the Beijing family to spread rapidly probably result from genetic advantages and unidentified mechanisms of virulence not yet thoroughly investigated. Among the mechanisms proposed to be responsible for the varying virulence phenotypes of M. tuberculosis strains we find IS6110 insertions, genetic reorganizations and deletions, which have strong influences on fitness. Beijing family is one of the lineages with the highest number of copies of IS6110. By studying genetic markers characteristic for this lineage, here we have characterized the clinical isolate M. tuberculosis GC1237 strain responsible for important epidemic outbreaks in the Gran Canary Island. We have identified and analyzed each point of insertion of IS6110 using a bacterial artificial chromosome (BAC) library of this strain, in addition to the use of other approximations. Nineteen copies of IS6110 have been localized in GC1237 genome of which, four copies of IS6110 can act as a promoter and we have focused in the characterization of one copy located 31 bp upstream of the essential gene Rv2179c and compared to the reference strain H37Rv.     

Effects of aging and methionine restriction applied at old age on ROS generation and oxidative damage in rat liver mitochondria

It is known that a global decrease in food ingestion (dietary restriction, DR) lowers mitochondrial ROS generation (mitROS) and oxidative stress in young immature rats. This seems to be caused by the decreased methionine ingestion of DR animals. This is interesting since isocaloric methionine restriction in the diet (MetR) also increases, like DR, rodent maximum longevity. However, it is not known if old rats maintain the capacity to lower mitROS generation and oxidative stress in response to MetR similarly to young immature animals, and whether MetR implemented at old age can reverse aging-related variations in oxidative stress. In this investigation the effects of aging and 7 weeks of MetR were investigated in liver mitochondria of Wistar rats. MetR implemented at old age decreased mitROS generation, percent free radical leak at the respiratory chain and mtDNA oxidative damage without changing oxygen consumption. Protein oxidation, lipoxidation and glycoxidation increased with age, and MetR in old rats partially or totally reversed these age-related increases. Aging increased the amount of SIRT1, and MetR decreased SIRT1 and TFAM and increased complex IV. No changes were observed in the protein amounts of PGC1, Nrf2, MnSOD, AIF, complexes I, II and III, and in the extent of genomic DNA methylation. In conclusion, treating old rats with isocaloric short-term MetR lowers mitROS production and free radical leak and oxidative damage to mtDNA, and reverses aging-related increases in protein modification. Aged rats maintain the capacity to lower mitochondrial ROS generation and oxidative stress in response to a short-term exposure to restriction of a single dietary substance: methionine.     

Documento de posicionamiento de la AEG,la SEED y la SEAP sobre calidad de la endoscopia digestiva alta para la detección y vigilancia de las lesiones precursoras de cáncer gástrico

This position paper, sponsored by the Asociación Española de Gastroenterología [Spanish Association of Gastroenterology], the Sociedad Española de Endoscopia Digestiva [Spanish Gastrointestinal Endoscopy Society] and the Sociedad Española de Anatomía Patológica [Spanish Anatomical Pathology Society], aims to establish recommendations for performing an high quality upper gastrointestinal endoscopy for the screening of gastric cancer precursor lesions (GCPL) in low-incidence populations, such as the Spanish population. To establish the quality of the evidence and the levels of recommendation, we used the methodology based on the GRADE system (Grading of Recommendations Assessment, Development and Evaluation). We obtained a consensus among experts using a Delphi method. The document evaluates different measures to improve the quality of upper gastrointestinal endoscopy in this setting and makes recommendations on how to evaluate and treat the identified lesions. We recommend that upper gastrointestinal endoscopy for surveillance of GCPL should be performed by endoscopists with adequate training, administering oral premedication and use of sedation. To improve the identification of GCPL, we recommend the use of high definition endoscopes and conventional or digital chromoendoscopy and, for biopsies, NBI should be used to target the most suspicious areas of intestinal metaplasia. Regarding the evaluation of visible lesions, the risk of submucosal invasion should be evaluated with magnifying endoscopes and endoscopic ultrasound should be reserved for those with suspected deep invasion. In lesions amenable to endoscopic resection, submucosal endoscopic dissection is considered the technique of choice.     

Non-reciprocal Friendships in a School-Age Boy with Autism: The Ties that Build?

This mixed-methods study examined differences in social interaction patterns between a school-age boy with autism and his friends, non-reciprocal friends, and non-friends during recess time at a mainstream school (third grade of elementary school). Through a combination of observational methodology and social network analysis with an idiographic, follow-up and multidimensional design approach, we used lag sequential and polar coordinate analysis to ascertain the associations between various interactive behaviors as a function of type of friendship relation. After 40 sessions, we found that the non-reciprocal friendship relations of the boy with autism could have significantly greater potential than his reciprocal friendships to increase active engagement and reduce the time he spent alone during recess.