ABSTRACT
The electronic and optical properties of finite silicene, graphene, and arsenene heterostructures are investigated using first principles calculations. The optoelectronic properties of these structures are precisely controlled, by chemical functionalization, shape, and size, to produce suitable donor energy gap and minimal conduction band offset that enable the construction of efficient heterojunction solar cells. Heterojunctions with only Van der Waals interactions between layers have been achieved in functionalized silicene/graphene and arsenene/graphene. The distribution of the highest occupied/lowest unoccupied molecular orbital on donor/acceptor layer in addition to the contribution of each layer into the total electronic density of states insure that the only interlayer interaction is the van der Waals one and charge separation is attained. The heterojunctions have donors' energy gaps ranging from 1.2 to 1.8â¯eV which in conjunction with the very low conduction band offsetâ¯â¼â¯0.002â¯eV enable the building of type-II solar cells with extremely high power conversion efficiency up to 23.34%. The prominent low energy optical excitations are mainly contributed by a transition from donor molecular orbitals to acceptor ones. Therefore, functionalized 2D heterojunctions are excellent candidates for building ultrathin, stable, and low-cost efficient solar cells.
ABSTRACT
OBJECTIVE: p53 antigen is an oncoprotective antigen and when damaged, leads to production of anti-p53 and also predisposes to various cancers, including hepatocellular carcinoma (HCC). Serum anti-p53 has been proven to have a prognostic value in patients with HCC. The objective of this study was to determine the prevalence and prognostic utility of serum anti-p53 in Egyptian patients with HCC. METHODS: Forty one patients with HCC, 26 patients with liver cirrhosis and 29 healthy controls were included in this study. For all the studied groups, we studied the clinical data, abdominal ultrasound (US) findings, biochemical liver function tests, serum alpha-fetoprotein (AFP) levels detected by enzyme immunoassay (EIA) kit and anti-p53 antibody levels by a modified enzyme-linked immunosorbent assay (ELISA). The severity of liver disease was assessed by Child-Pugh and MELD scores. Tumor characteristics were detected by (US) with or without computed tomography (CT) scan. These characteristics included tumor size, number and site. Tumor staging was done using Okuda, Cancer Liver Italian Program (CLIP) and Tokyo staging systems. Also, the overall survival of patients with HCC with reference to p53 antibody level was studied. RESULTS: The mean age of HCC patients was 57.95+/-8.41. There was a male predominance among HCC patients with male-to-female ratio of 3.6:1. Anti-p53 antibodies were detected in the sera of 68.3% of HCC patients, 50% of liver cirrhosis patients and 17.2% of healthy control subjects. The data showed that HCC patients had a significantly higher mean anti-p53 antibody values (p=0.0001), than both liver cirrhosis patients and healthy control groups. Our results revealed that anti-p53 has a positive significant correlation with AFP (p=0.002), severity of liver disease [Child Pugh score (p=0.02) and MELD score (p=0.0003)], tumor size (p<0.0001), tumor number (p=0.003) and tumor staging systems [Okuda (p=0.04), CLIP (p=0.006) and Tokyo (p<0.0001)]. Also, our results revealed that serum anti-p53 antibodies had a significant association with overall survival of patients with HCC (p=0.019) with a shorter survival time in anti-p53 positive status patients and with higher anti-p53 antibody levels within 19 months follow up. CONCLUSION: The detection of anti-p53 antibodies may be suitable for assessing the prognosis of HCC patients. The higher percentage of positivity of anti-p53 antibodies in Egyptian control subjects than reported elsewhere needs further thorough investigation.
