Solution Processable Nanostructures for Molecular Electronics

PhDIn molecular electronics, the building material (traditionally elemental semiconductor) is replaced by single molecules or a nanoscale collection of molecules. Key to molecular electronics is the ability to precisely embed molecules into a nano device/structure and to manipulate large numbers of functional devices so they can be built in parallel, with each nano-device precisely located on the electrodes. In this work, the assembly of organic and inorganic nanostructures dispersed in aqueous solutions has been controlled via chemical functionalisation. By combining this bottom-up assembly strategy with traditional top-down lithographic apporaches, the properties of these nanostructures have been investigated via a range of different techniques. The high degree of control on the molecular design through chemical synthesis and the scalability by self-assembly make this approach of interest in the field of molecular electronics. In this regard, this dissertation presents a solution-based assembly method for producing molecular transport junctions employing metallic single-walled carbon nanotubes as nanoelectrodes. On solid substrates, electrical and electronic properties have been investigated by Conducting Atomic Force Microscopy (C-AFM). Furthermore, different strategies for asymmetric junction formation have been explored towards the development of a potential nanoscale Schottky diode. Moreover, various patterning techniques based on shadow evaporation and AFM probe scratching have been investigated for the assembly of 1-D nanostructures. Nanostructures dispersed in solution were organised onto surfaces by means of dielectrophoretic assembly, and their electronic properties was then measured by the means of a probing station. In addition to the aforementioned organic nanostructures, we also report on the dispersion of boron nitride nanotubes (BNNT) by DNA wrapping, followed by the formation of nano-hybrids of boron nitride nanotubes and carbon nanotubes. Previously, researchers have adopted BNNT as a 2D dielectric layer. The work inspires me to adopt boron nitride nanotubes as 1D dielectric materials. The techniques developed in this thesis are of interest for fundamental studies of electron transport in molecules and nanostructures. Addtionally, the approaches developed in this work may facilitate the advancement of new technologies for electronics, including, but not limited to, future circuits based on single-wall carbon/boron nitride nanotubes with specific functionality

Few-shot Image Generation via Masked Discrimination

Few-shot image generation aims to generate images of high quality and great diversity with limited data. However, it is difficult for modern GANs to avoid overfitting when trained on only a few images. The discriminator can easily remember all the training samples and guide the generator to replicate them, leading to severe diversity degradation. Several methods have been proposed to relieve overfitting by adapting GANs pre-trained on large source domains to target domains with limited real samples. In this work, we present a novel approach to realize few-shot GAN adaptation via masked discrimination. Random masks are applied to features extracted by the discriminator from input images. We aim to encourage the discriminator to judge more diverse images which share partially common features with training samples as realistic images. Correspondingly, the generator is guided to generate more diverse images instead of replicating training samples. In addition, we employ cross-domain consistency loss for the discriminator to keep relative distances between samples in its feature space. The discriminator cross-domain consistency loss serves as another optimization target in addition to adversarial loss and guides adapted GANs to preserve more information learned from source domains for higher image quality. The effectiveness of our approach is demonstrated both qualitatively and quantitatively with higher quality and greater diversity on a series of few-shot image generation tasks than prior methods

The Structure and Clinical Roles of MicroRNA in Colorectal Cancer

Colorectal cancer (CRC) is one of the most prevalent types of malignancies, particularly among individuals aged between 50 and 75. The global incidence of CRC has been steadily on the rise due in no small part to an aging population and a shift in lifestyle as well as eating habits. MicroRNAs are a group of small, noncoding, and endogenous RNA molecules that have recently emerged as key players in a broad range of pathological pathways. Moreover, dysregulation of microRNAs has been implicated in cancer development and metastasis. This review is intended to provide a brief overview of the structure, functions, and clinical roles of microRNAs. In particular, the review will focus on the discovery, the underlying mechanistic roles, and the diagnostic as well as therapeutic potentials of CRC-specific miRNAs

Effect of combined vitamin D and microwave ablation of parathyroid glands on blood pressure and cardiac function in maintenance-hemodialysis patients with uremic secondary hyperparathyroidism

Purpose: To investigate the effect of microwave ablation of parathyroid glands in combination with active vitamin D on blood pressure and cardiac function in maintenance-hemodialysis patients with uremic secondary hyperparathyroidism. Methods: One hundred and twenty maintenance-hemodialysis patients with uremic secondary hyperparathyroidism admitted to Meizhou People’s Hospital were assigned to 2 groups (A and B) in the order of their admission. Each group had 60 patients. Both groups were treated with active vitamin D, while patients in group A were, in addition, subjected to microwave ablation of parathyroid glands. Blood pressure, and indices for cardiac function, thyroid function s and anemia were determined. Results: After treatment, the blood pressure of group A was significantly lower than that of group B (p < 0.05). Moreover, after treatment, there were significant improvements in indices of cardiac function, thyroid function and anemia in group A patients, relative to group B patients. Conclusion: Microwave ablation of parathyroid glands, when combined with active vitamin D, improves blood pressure, cardiac function and anemia status. Furthermore, the combined therapy enhances recovery of thyroid function in maintenance-hemodialysis patients with uremic secondary hyperparathyroidism. However, the combined therapy should be subjected to further clinical trials prior to application in clinical practice. Keywords: Microwave ablation; Parathyroid glands; Active vitamin D; Hyperparathyroidis

Immediate response of paddy soil microbial community and structure to moisture changes and nitrogen fertilizer application

Water and fertilizer managements are the most common practices to maximize crop yields, and their long-term impact on soil microbial communities has been extensively studied. However, the initial response of microbes to fertilization and soil moisture changes remains unclear. In this study, the immediate effects of nitrogen (N)-fertilizer application and moisture levels on microbial community of paddy soils were investigated through controlled incubation experiments. Amplicon sequencing results revealed that moisture had a stronger influence on the abundance and community composition of total soil bacteria, as well as ammonia oxidizing-archaea (AOA) and -bacteria (AOB). Conversely, fertilizer application noticeably reduced the connectivity and complexity of the total bacteria network, and increasing moisture slightly exacerbated these effects. NH4+-N content emerged as a significant driving force for changes in the structure of the total bacteria and AOB communities, while NO3−-N content played more important role in driving shifts in AOA composition. These findings indicate that the initial responses of microbial communities, including abundance and composition, and network differ under water and fertilizer managements. By providing a snapshot of microbial community structure following short-term N-fertilizer and water treatments, this study contributes to a better understanding of how soil microbes respond to long-term agriculture managements

Use of ITS2 Region as the Universal DNA Barcode for Plants and Animals

The internal transcribed spacer 2 (ITS2) region of nuclear ribosomal DNA is regarded as one of the candidate DNA barcodes because it possesses a number of valuable characteristics, such as the availability of conserved regions for designing universal primers, the ease of its amplification, and sufficient variability to distinguish even closely related species. However, a general analysis of its ability to discriminate species in a comprehensive sample set is lacking.In the current study, 50,790 plant and 12,221 animal ITS2 sequences downloaded from GenBank were evaluated according to sequence length, GC content, intra- and inter-specific divergence, and efficiency of identification. The results show that the inter-specific divergence of congeneric species in plants and animals was greater than its corresponding intra-specific variations. The success rates for using the ITS2 region to identify dicotyledons, monocotyledons, gymnosperms, ferns, mosses, and animals were 76.1%, 74.2%, 67.1%, 88.1%, 77.4%, and 91.7% at the species level, respectively. The ITS2 region unveiled a different ability to identify closely related species within different families and genera. The secondary structure of the ITS2 region could provide useful information for species identification and could be considered as a molecular morphological characteristic.)

Amino acid Formula induces Microbiota Dysbiosis and Depressive-Like Behavior in Mice

Amino acid formula (AAF) is increasingly consumed in infants with cow\u27s milk protein allergy; however, the long-term influences on health are less described. In this study, we established a mouse model by subjecting neonatal mice to an amino acid diet (AAD) to mimic the feeding regimen of infants on AAF. Surprisingly, AAD-fed mice exhibited dysbiotic microbiota and increased neuronal activity in both the intestine and brain, as well as gastrointestinal peristalsis disorders and depressive-like behavior. Furthermore, fecal microbiota transplantation from AAD-fed mice or AAF-fed infants to recipient mice led to elevated neuronal activations and exacerbated depressive-like behaviors compared to that from normal chow-fed mice or cow\u27s-milk-formula-fed infants, respectively. Our findings highlight the necessity to avoid the excessive use of AAF, which may influence the neuronal development and mental health of children

Root nutrient capture and leaf resorption efficiency modulated by different influential factors jointly alleviated P limitation in Quercus acutissima across the North–South Transect of Eastern China

Soil and climatic conditions are known to have close associations with plant morphological and stoichiometric traits at a regional scale along latitudinal gradients; however, how latitude drives biotic and abiotic factors affecting plant nutrient acquisition to accommodate environmental nutrient deficiency remains unclear. We quantified soil, root, leaf, and leaf litter nitrogen (N) and phosphorus (P) concentrations to determine the potentially limiting nutrient and the simultaneous responses of root capture and leaf resorption to nutrient deficiency in seven Quercus acutissima forests across the North–South Transect of Eastern China. The results showed that the mean leaf and root N:P ratios in Q. acutissima were 21.58 and 20.23, respectively, which markedly exceeded the P limitation threshold of 16 for terrestrial plants. The mean leaf litter N and P were 10.63 mg/g and 0.51 mg/g, respectively, indicating that P resorption proficiency was relatively higher than N resorption proficiency. N displayed higher stoichiometric homeostasis than P in the leaf. The leaf and root N:P ratios showed a quadratic variation that first decreased and then increased as latitude increased, whereas the phosphorus resorption efficiency and root-soil accumulation factor of P displayed the opposite trend. Partial least square path modeling (PLS-PM) analysis demonstrated that root nutrient capture and leaf nutrient resorption were regulated by different influential factors. Overall, these findings provide new insights into plant strategies to adapt to environmental nutrient deficiency, as well as the scientific basis for predicting the spatial and temporal patterns of nutrient acquisition in the context of climate change