Berry Phase Effects on Electronic Properties

Ever since its discovery, the Berry phase has permeated through all branches of physics. Over the last three decades, it was gradually realized that the Berry phase of the electronic wave function can have a profound effect on material properties and is responsible for a spectrum of phenomena, such as ferroelectricity, orbital magnetism, various (quantum/anomalous/spin) Hall effects, and quantum charge pumping. This progress is summarized in a pedagogical manner in this review. We start with a brief summary of necessary background, followed by a detailed discussion of the Berry phase effect in a variety of solid state applications. A common thread of the review is the semiclassical formulation of electron dynamics, which is a versatile tool in the study of electron dynamics in the presence of electromagnetic fields and more general perturbations. Finally, we demonstrate a re-quantization method that converts a semiclassical theory to an effective quantum theory. It is clear that the Berry phase should be added as a basic ingredient to our understanding of basic material properties.Comment: 48 pages, 16 figures, submitted to RM

An atmospheric correction algorithm for FY3/MERSI data over land in China

Feng-Yun (FY-3) is the second generation of the Chinese Polar Orbiting Meteorological Satellites with global, three-dimensional, quantitative, and multispectral capabilities. Medium Resolution Spectral Imager (MERSI) has 20 channels onboard the FY-3A and FY-3B satellites, including five channels (four VIS and one thermal IR) with a spatial resolution of 250m. The top of the atmosphere signal are necessary to be radiometrically calibrated and corrected for atmospheric effects based on surface reflectance, especially in land surface remote sensing and applications. This paper presents an atmospheric correction algorithm for FY3/MERSI data over land in China, taking into account the directional properties of the observed surface by a kernel-based Bi-directional Reflectance Distribution Function (BRDF) model. The comparison with MODGA and ASD reflectance showed that there is a good agreement. Therefore, FY3/MERSI can serve a reliable and new data source for quantifying global environment change

Evaluation of PD-L1 expression on vortex-isolated circulating tumor cells in metastatic lung cancer.

Metastatic non-small cell lung cancer (NSCLC) is a highly fatal and immunogenic malignancy. Although the immune system is known to recognize these tumor cells, one mechanism by which NSCLC can evade the immune system is via overexpression of programmed cell death ligand 1 (PD-L1). Recent clinical trials of PD-1 and PD-L1 inhibitors have returned promising clinical responses. Important for personalizing therapy, patients with higher intensity staining for PD-L1 on tumor biopsies responded better. Thus, there has been interest in using PD-L1 tumor expression as a criterion for patient selection. Currently available methods of screening involve invasive tumor biopsy, followed by histological grading of PD-L1 levels. Biopsies have a high risk of complications, and only allow sampling from limited tumor sections, which may not reflect overall tumor heterogeneity. Circulating tumor cell (CTC) PD-L1 levels could aid in screening patients, and could supplement tissue PD-L1 biopsy results by testing PD-L1 expression from disseminated tumor sites. Towards establishing CTCs as a screening tool, we developed a protocol to isolate CTCs at high purity and immunostain for PD-L1. Monitoring of PD-L1 expression on CTCs could be an additional biomarker for precision medicine that may help in determining response to immunotherapies

Label-free isolation of prostate circulating tumor cells using Vortex microfluidic technology.

There has been increased interest in utilizing non-invasive "liquid biopsies" to identify biomarkers for cancer prognosis and monitoring, and to isolate genetic material that can predict response to targeted therapies. Circulating tumor cells (CTCs) have emerged as such a biomarker providing both genetic and phenotypic information about tumor evolution, potentially from both primary and metastatic sites. Currently, available CTC isolation approaches, including immunoaffinity and size-based filtration, have focused on high capture efficiency but with lower purity and often long and manual sample preparation, which limits the use of captured CTCs for downstream analyses. Here, we describe the use of the microfluidic Vortex Chip for size-based isolation of CTCs from 22 patients with advanced prostate cancer and, from an enumeration study on 18 of these patients, find that we can capture CTCs with high purity (from 1.74 to 37.59%) and efficiency (from 1.88 to 93.75 CTCs/7.5 mL) in less than 1 h. Interestingly, more atypical large circulating cells were identified in five age-matched healthy donors (46-77 years old; 1.25-2.50 CTCs/7.5 mL) than in five healthy donors <30 years old (21-27 years old; 0.00 CTC/7.5 mL). Using a threshold calculated from the five age-matched healthy donors (3.37 CTCs/mL), we identified CTCs in 80% of the prostate cancer patients. We also found that a fraction of the cells collected (11.5%) did not express epithelial prostate markers (cytokeratin and/or prostate-specific antigen) and that some instead expressed markers of epithelial-mesenchymal transition, i.e., vimentin and N-cadherin. We also show that the purity and DNA yield of isolated cells is amenable to targeted amplification and next-generation sequencing, without whole genome amplification, identifying unique mutations in 10 of 15 samples and 0 of 4 healthy samples

Classification of large circulating tumor cells isolated with ultra-high throughput microfluidic Vortex technology.

Circulating tumor cells (CTCs) are emerging as rare but clinically significant non-invasive cellular biomarkers for cancer patient prognosis, treatment selection, and treatment monitoring. Current CTC isolation approaches, such as immunoaffinity, filtration, or size-based techniques, are often limited by throughput, purity, large output volumes, or inability to obtain viable cells for downstream analysis. For all technologies, traditional immunofluorescent staining alone has been employed to distinguish and confirm the presence of isolated CTCs among contaminating blood cells, although cells isolated by size may express vastly different phenotypes. Consequently, CTC definitions have been non-trivial, researcher-dependent, and evolving. Here we describe a complete set of objective criteria, leveraging well-established cytomorphological features of malignancy, by which we identify large CTCs. We apply the criteria to CTCs enriched from stage IV lung and breast cancer patient blood samples using the High Throughput Vortex Chip (Vortex HT), an improved microfluidic technology for the label-free, size-based enrichment and concentration of rare cells. We achieve improved capture efficiency (up to 83%), high speed of processing (8 mL/min of 10x diluted blood, or 800 μL/min of whole blood), and high purity (avg. background of 28.8±23.6 white blood cells per mL of whole blood). We show markedly improved performance of CTC capture (84% positive test rate) in comparison to previous Vortex designs and the current FDA-approved gold standard CellSearch assay. The results demonstrate the ability to quickly collect viable and pure populations of abnormal large circulating cells unbiased by molecular characteristics, which helps uncover further heterogeneity in these cells

Treating farm dairy effluent with poly‐ferric sulphate dramatically reduces phosphorus and E. coli leaching through subsurface drains—A physical drainage model study

Land application of farm dairy effluent (FDE) may lead to water contamination, by contaminants such as phosphorus (P) and E. coli. A new FDE treatment technology using poly-ferric sulphate (PFS) has been developed to recycle wastewater in FDE for washing the farmyard. A physical drainage model study was conducted to investigate the effect of treating FDE with PFS on phosphorus and E. coli leaching through model subsurface drains. Dissolved reactive phosphorus (DRP) and total phosphorus (TP) leaching losses from untreated effluent (FDE) averaged 3.48 kg P ha¯¹ and 11.44 kg P ha¯¹, respectively. The application of PFS-treated effluent (TE) resulted in significantly lower DRP and TP leaching losses at 0.24 kg P ha¯¹ and 4.52 kg P ha¯¹ for fresh TE and 0.27 kg P ha¯¹ and 6.31 kg P ha¯¹ for TE stored for 3 weeks before application (TE-S). Cumulative DRP lost to drainage water from the TE and TE-S treatments was 93.1% and 92.2% lower than that from the FDE treatments. Compared with the FDE treatment, there was a 98.27% and 99.99% reduction in E. coli in the drainage water from the TE and TE-S treatments. Plant biomass and P uptake were not affected by the effluent treatments. These results indicate that land application of PFS-treated effluent, fresh or stored, on drained pasture soils can produce significant environmental benefits by reducing the concentration and amount of P and E. coli in the drainage water, without adversely impacting plant growth

Kinetics of non-structural protein 1, IgM and IgG antibodies in dengue type 1 primary infection

<p>Abstract</p> <p>Background</p> <p>Early and accurate diagnosis of dengue infection is essential for control of disease outbreaks. Recently, the dengue virus non-structural antigen 1 (NS1), a conserved and secreted glycoprotein, has been used as a marker for early diagnosis of dengue with convenience and cost-effectiveness. Serological tests of dengue IgM and IgG antibodies are still the most widely used for diagnosis of dengue. In order to assess combined diagnostic value of these tests, we study the kinetic profiles of circulating NS1, dengue IgM and IgG antibodies over the course of the disease by using an in-house dengue type 1 (DENV1) specific NS1 capture ELISA and the commercial Panbio Dengue IgM and IgG capture ELISAs.</p> <p>Results</p> <p>A panel of 313 acute-and early convalescent-phase serum specimens from 140 DENV1 primary infected patients during an outbreak of dengue in Guangzhou, China, in 2006 were studied. Dengue NS1 presented high levels in acute-phase serum samples. It was detectable as early as day 1 of illness, and up to 14 day after onset. The sensitivity of NS1 detection was ranged from 81.8% to 91.1% with samples taken during the first 7 days. Anti-dengue IgM antibody was detectable on the third day of onset with the positive rate of 42.9%, and rapidly increasing to 100% by day 8 of illness. Anti-dengue IgG antibody was detectable on the fifth day of onset with low level at the first week of onset, and slowly increasing to 100% by day 15 of illness. Combining the results of NS1 and IgM antibody detection allowed positive diagnosis in 96.9% -100% for samples taken after day 3 of onset.</p> <p>Conclusions</p> <p>Dengue NS1 detection might shorten the window period by first few days of illness. A combination of dengue NS1 antigen and IgM antibody testing facilitates enhanced diagnosis rates. The procedures should be suitable for developing countries where dengue is endemic.</p