Wetting layer evolution and its temperature dependence during self assembly of InAs/GaAs quantum dots

For InAs/GaAs(001) quantum dot (QD) system, the wetting layer (WL) evolution and its temperature dependence were studied using reflectance difference spectroscopy (RDS) and analyzed with a rate equation model. The WL thicknesses showed a monotonic increase at relatively low growth temperatures but a first increase and then decrease at higher temperatures, which were unexpected from the thermodynamic understanding. By adopting a rate equation model, the temperature dependence of QD growth was assigned as the origin of different WL evolutions. A brief discussion on the indium desorption was also given. Those results gave hints of the kinetic aspects of QD self-assembly.Comment: 13 pages, 3 figure

Valence band offset of InN/BaTiO3 heterojunction measured by X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy has been used to measure the valence band offset of the InN/BaTiO(3 )heterojunction. It is found that a type-I band alignment forms at the interface. The valence band offset (VBO) and conduction band offset (CBO) are determined to be 2.25 ± 0.09 and 0.15 ± 0.09 eV, respectively. The experimental VBO data is well consistent with the value that comes from transitivity rule. The accurate determination of VBO and CBO is important for use of semiconductor/ferrroelectric heterojunction multifunctional devices

Morphological Characterization of a New and Easily Recognizable Nuclear Male Sterile Mutant of Sorghum (\u3ci\u3eSorghum bicolor\u3c/i\u3e)

Sorghum (Sorghum bicolor L. Moench) is one of the most important grain crops in the world. The nuclear male sterility (NMS) trait, which is caused by mutations on the nuclear gene, is valuable for hybrid breeding and genetic studies. Several NMS mutants have been reported previously, but none of them were well characterized. Here, we present our detailed morphological characterization of a new and easily recognizable NMS sorghum mutant male sterile 8 (ms8) isolated from an elite inbred BTx623 mutagenized by ethyl methane sulfonate (EMS). Our results show that the ms8 mutant phenotype was caused by a mutation on a single recessive nuclear gene that is different from all available NMS loci reported in sorghum. In fertile sorghum plants, yellow anthers appeared first during anthesis, while in the ms8 mutant, white hairy stigma emerged first and only small white anthers were observed, making ms8 plants easily recognizable when flowering. The ovary development and seed production after manual pollination are normal in the ms8 mutant, indicating it is female fertile and male sterile only. We found that ms8 anthers did not produce pollen grains. Further analysis revealed that ms8 anthers were defective in tapetum development, which led to the arrest of pollen formation. As a stable male sterile mutant across different environments, greenhouses, and fields in different locations, the ms8 mutant could be a useful breeding tool. Moreover, ms8 might be an important for elucidating male gametophyte development in sorghum and other plants

Effect of growth temperature on the morphology and phonon properties of InAs nanowires on Si substrates

Catalyst-free, vertical array of InAs nanowires (NWs) are grown on Si (111) substrate using MOCVD technique. The as-grown InAs NWs show a zinc-blende crystal structure along a < 111 > direction. It is found that both the density and length of InAs NWs decrease with increasing growth temperatures, while the diameter increases with increasing growth temperature, suggesting that the catalyst-free growth of InAs NWs is governed by the nucleation kinetics. The longitudinal optical and transverse optical (TO) mode of InAs NWs present a phonon frequency slightly lower than those of InAs bulk materials, which are speculated to be caused by the defects in the NWs. A surface optical mode is also observed for the InAs NWs, which shifts to lower wave-numbers when the diameter of NWs is decreased, in agreement with the theory prediction. The carrier concentration is extracted to be 2.25 × 1017 cm-3 from the Raman line shape analysis. A splitting of TO modes is also observed

Research trends and hot spots in global nanotechnology applications in liver cancer: a bibliometric and visual analysis (2000-2022)

BackgroundLiver cancer (LC) is one of the most common malignancies. Currently, nanotechnology has made great progress in LC research, and many studies on LC nanotechnology have been published. This study aims to discuss the current status, hot spots, and research trends in this field through bibliometric analysis.MethodsThe Web of Science Core Collection (WoSCC) database was searched for papers related to hepatocellular carcinoma (HCC) included from January 2000 to November 2022, and its research hotspots and trends were visualized and analyzed with the help of VOSviewer. In addition, a search was conducted to find LC papers related to nanotechnology. Then we used the visual analysis software VOSviewer and CiteSpace to evaluate the contributions of countries/regions, authors, and journals related to the topic and analyze keywords to understand the research priorities and hot spots in the field as well as the development direction.ResultsThere are 1908 papers in the highly cited literature on LC, and its research hotspots are pathogenesis, risk factors, and survival rate. The literature on the application of nanotechnology in LC had 921 papers. Among them, China (n=560, 60.8%) and the United States (n=170, 18.5%) were the countries with the highest number of published papers. Wang Yan (n=11) and Llovet JM (n=131) were the first authors and co-cited authors, respectively. The International Journal of Nanomedicine was the most prolific academic journal (n=41). In addition to “hepatocellular carcinoma” and “nanoparticles”, the most frequent keyword was “drug delivery”. In recent years, “metastasis” and “diagnosis” appeared in the keyword bursts. This indicates that the application of nanoparticles in the early diagnosis and drug delivery of LC (including liver metastasis) has a good prospect.ConclusionNanotechnology has received more and more attention in the medical field in recent years. As nanoparticles are easily localized in organelles and cells, they can increase drug permeability in tumor tissues, improve drug delivery efficiency and reduce drug toxicity. Our research results were the first scientific evaluation of the application of nanotechnology in LC, providing scholars with research hotspots and development trends

Sorghum bicolor INDETERMINATE1 is a conserved primary regulator of flowering

IntroductionA fundamental developmental switch for plants is transition from vegetative to floral growth, which integrates external and internal signals. INDETERMINATE1 (Id1) family proteins are zinc finger transcription factors that activate flowering in grasses regardless of photoperiod. Mutations in maize Id1 and rice Id1 (RID1) cause very late flowering. RID1 promotes expression of the flowering activator genes Early Heading Date1 (Ehd1) and Heading date 1 (Hd1), a rice homolog of CONSTANS (CO).Methods and resultsMapping of two recessive late flowering mutants from a pedigreed sorghum EMS mutant library identified two distinct mutations in the Sorghum bicolor Id1 (SbId1) homolog, mutant alleles named sbid1-1 and sbid1-2. The weaker sbid1-1 allele caused a 35 day delay in reaching boot stage in the field, but its effect was limited to 6 days under greenhouse conditions. The strong sbid1-2 allele delayed boot stage by more than 60 days in the field and under greenhouse conditions. When sbid1-1 and sbid1-2 were combined, the delayed flowering phenotype remained and resembled that of sbid1-2, confirming late flowering was due to loss of SbId1 function. Evaluation of major flowering time regulatory gene expression in sbid1-2 showed that SbId1 is needed for expression of floral activators, like SbCO and SbCN8, and repressors, like SbPRR37 and SbGhd7.DiscussionThese results demonstrate a conserved role for SbId1 in promotion of flowering in sorghum, where it appears to be critical to allow expression of most major flowering regulatory genes

Association of Short Tandem Repeat Polymorphism in the Promoter of Prostate Cancer Antigen 3 Gene with the Risk of Prostate Cancer

BACKGROUND: PCA3 (prostate cancer antigen 3) gene is one of the most prostate cancer-specific genes at present. Consequently, the prostate-specific expression and the sharp up-regulation of PCA3 mRNA in prostate cancer suggest a unique transcriptional regulation, which possibly can be attributed to promoter polymorphism. In our study, we evaluated whether there is polymorphism in PCA3 promoter region and also assess the association of the polymorphism with prostate cancer. METHODOLOGY/PRINCIPAL FINDINGS: We designed a specific primer set to screen the promoter of PCA3 gene by polymerase chain reaction (PCR)-based cloning and sequencing with the DNA extracted from peripheral blood samples of prostate cancer (PCa) cases (n = 186) and healthy control cases (n = 135). Genotype-specific risks were estimated as odds ratios (ORs) with associated 95% confidence intervals (CIs) by chi-square test. Possible deviation of the genotype frequencies from controls and PCa cases expected under Hardy-Weinberg equilibrium was assessed by the chi-square test. Short tandem repeat polymorphism of TAAA was found in the promoter region of PCA3 gene, five polymorphisms and eight genotypes were identified. The eight genotypes were divided into three groups: ≤10TAAA, 11TAAA, ≥12TAAA. The group 11TAAA and ≥12TAAA were associated with higher relative risk for prostate cancer than group ≤10TAAA (OR = 1.76, 95%CI = 1.07-2.89[for group 11TAAA]; OR = 5.28, 95%CI = 1.76-15.89[for group ≥12TAAA]). CONCLUSIONS/SIGNIFICANCE: The presence of the (TAAA)n short tandem repeat polymorphisms in the PCA3 promoter region may be a risk factor for prostate cancer in the Chinese population