The structural, mechanical and electronic properties of Ti-Al-based compounds by first-principles calculations.

The first-principles calculations with density functional theory were performed to investigate the effects of transition metal elements (Mo, Cu, Fe, Ni and Nb) on the physical properties of the Ti-Al-based compounds. Our optimized crystal parameters are in good agreement with the previous theoretical and experimental values. The mechanical stability is verified by the independent elastic constants. The B/G and Poisson's ratio ν both show that Al6TiMo is brittle, while other compounds exhibit ductility. The values of compression anisotropy of the compounds are small, but the shear anisotropy of AlCu2Ti and AlNi2Ti is much more intense than that of other compounds. The anisotropy in elastic properties of AlFe2Ti and AlNbTi2 is smaller than that of the others. It can be seen that the capacity to compress along c-axis is smaller than that along a-axis and b-axis for AlNbTi2. For AlNbTi2, the anisotropy of the bulk modulus along a-axis relative to b-axis is more insignificant than that along c-axis relative to b-axis. The hardness and Debye temperature verify that AlFe2Ti has the greatest resistance to the plastic deformation and more intense inter-atomic bonding force, respectively. Band structures and DOS are used to investigate the electronic properties. The band structures without band gaps show that these ternary Ti-Al-based compounds are conductors. DOS shows the interactions between elements and gives the bond properties. Density of states and charge density both show the strong covalent properties of AlFe2Ti by the hybridization between Fe-3d and Ti-3d states.

Adrenal Crisis Mimicking COVID-19 Encephalopathy in a Teenager with Craniopharyngioma.

There is an increasing number of reported cases with neurological manifestations of COVID-19 in children. Symptoms include headache, general malaise, ageusia, seizure and alterations in consciousness. The differential diagnosis includes several potentially lethal conditions including encephalopathy, encephalitis, intracranial hemorrhage, thrombosis and adrenal crisis. We report the case of a 17-year-old boy with a positive antigen test of COVID-19 who presented with fever for one day, altered mental status and seizure, subsequently diagnosed with adrenal insufficiency. He had a history of panhypopituitarism secondary to a suprasellar craniopharyngioma treated with surgical resection; he was treated with regular hormone replacement therapy. After prompt administration of intravenous hydrocortisone, his mental status returned to normal within four hours. He recovered without neurologic complications. Adrenal insufficiency can present with neurological manifestations mimicking COVID-19 encephalopathy. Prompt recognition and treatment of adrenal insufficiency, especially in patients with brain tumors, Addison's disease or those recently treated with corticosteroids, can rapidly improve the clinical condition and prevent long-term consequences.

Morbidity and mortality of very low birth weight infants in Taiwan-Changes in 15 years: A population based study.

BACKGROUND/PURPOSE: Very low birth weight (VLBW) infants account for over 50% of perinatal deaths in Taiwan. This study aimed to identify changes in parental characteristics, perinatal conditions, mortality, and major neonatal morbidities for VLBW infants in Taiwan, and to highlight the challenges faced by patients, families, and caregivers. METHODS: We conducted a retrospective cohort study to investigate the mortality and morbidity of VLBW infants registered in the Taiwan Premature Infant Follow-up Network from 1997 through 2011. The exclusion criteria included congenital anomalies and chromosome anomalies. Continuous data was represented as mean ± SD, and changes over time in the variables were tested using one-way analysis of variance, with p < 0.05 considered statistically significant. RESULTS: A total of 13,159 VLBW infants were enrolled. We found significant increases over time in the parental age and educational level, in vitro fertilization, first livebirth, multiple births, maternal transfer, cesarean section, and complete antenatal steroid use. Apgar scores at 1 minute and 5 minutes after birth increased, and the intubation rate decreased gradually. Decreasing mortality over time for each successive period was demonstrated. Incidence of some morbidities increased, such as respiratory distress syndrome and patent ductus arteriosus; in contrast, incidence of others decreased, such as sepsis, necrotizing enterocolitis, intraventricular hemorrhage, and chronic lung disease. However, retinopathy of prematurity (ROP) incidence remained constant. CONCLUSION: Although the mortality and most of the morbidity of VLBW infants improved over time, the incidence of ROP remained constant. This requires us to further evaluate our strategy for preventing ROP in the future.

A novel sensitive pathogen detection system based on Microbead Quantum Dot System.

A fast and accurate detection system for pathogens can provide immediate measurements for the identification of infectious agents. Therefore, the Microbead Quantum-dots Detection System (MQDS) was developed to identify and measure target DNAs of pathogenic microorganisms and eliminated the need of PCR amplifications. This nanomaterial-based technique can detect different microorganisms by flow cytometry measurements. In MQDS, pathogen specific DNA probes were designed to form a hairpin structure and conjugated on microbeads. In the presence of the complementary target DNA sequence, the probes will compete for binding with the reporter probes but will not interfere with the binding between the probe and internal control DNA. To monitor the binding process by flow cytometry, both the reporter probes and internal control probes were conjugated with Quantum dots that fluoresce at different emission wavelengths using the click reaction. When MQDS was used to detect the pathogens in environmental samples, a high correlation coefficient (R=0.994) for Legionella spp., with a detection limit of 0.1 ng of the extracted DNAs and 10 CFU/test, can be achieved. Thus, this newly developed technique can also be applied to detect other pathogens, particularly viruses and other genetic diseases.

Down-regulation of NDRG1 promotes migration of cancer cells during reoxygenation.

One characteristic of tumor microenvironment is oxygen fluctuation, which results from hyper-proliferation and abnormal metabolism of tumor cells as well as disorganized neo-vasculature. Reoxygenation of tumors can induce oxidative stress, which leads to DNA damage and genomic instability. Although the cellular responses to hypoxia are well known, little is known about the dynamic response upon reoxygenation. In order to investigate the transcriptional responses of tumor adaptation to reoxygenation, breast cancer MCF-7 cells were cultured under 0.5% oxygen for 24 h followed by 24 h of reoxygenation in normoxia. Cells were harvested at 0, 1, 4, 8, 12, and 24 h during reoxygenation. The transcriptional profile of MCF-7 cells upon reoxygenation was examined using Illumina Human-6 v3 BeadChips. We identified 127 differentially expressed genes, of which 53.1% were up-regulated and 46.9% were down-regulated upon reoxygenation. Pathway analysis revealed that the HIF-1-alpha transcription factor network and validated targets of C-MYC transcriptional activation were significantly enriched in these differentially expressed genes. Among these genes, a subset of interest genes was further validated by quantitative reverse-transcription PCR. In particular, human N-MYC down-regulated gene 1 (NDRG1) was highly suppressed upon reoxygenation. NDRG1 is associated with a variety of stress and cell growth-regulatory conditions. To determine whether NDRG1 plays a role in reoxygenation, NDRG1 protein was overexpressed in MCF-7 cells. Upon reoxygenation, overexpression of NDRG1 significantly inhibited cell migration. Our results revealed the dynamic nature of gene expression in MCF-7 cells upon reoxygenation and demonstrated that NDRG1 is involved in tumor adaptation to reoxygenation.