Publications by authors named "Xifeng Yang"

12 Publications

  • Page 1 of 1

Enhanced Optical Absorption in Perovskite/Si Tandem Solar Cells with Nanoholes Array.

Nanoscale Res Lett 2020 Nov 12;15(1):213. Epub 2020 Nov 12.

School of Electronics and Information Engineering, Changshu Institute of Technology, Changshu, 215500, China.

Perovskite solar cells are used in silicon-based tandem solar cells due to their tunable band gap, high absorption coefficient and low preparation cost. However, the relatively large optical refractive index of bottom silicon, in comparison with that of top perovskite absorber layers, results in significant reflection losses in two-terminal devices. Therefore, light management is crucial to improve photocurrent absorption in the Si bottom cell. In this paper, nanoholes array filled with TiO is introduced into bottom cells design. By finite-difference time-domain methods, the absorption efficiency and photocurrent density in the range of 300-1100 nm has been analyzed, and the structural parameters have been also optimized. Our calculations show the photocurrent density which tends to be saturated with the increase in the height of the nanoholes. The absorption enhancement modes of photons at different wavelengths have been analyzed intuitively by the distribution of electric field. These results enable a viable and convenient route toward high efficiency design of perovskite/Si tandem solar cells.
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http://dx.doi.org/10.1186/s11671-020-03445-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7661566PMC
November 2020

Whole-Genome Assemblies for Three Yersinia pestis Strains Isolated in Erenhot, China.

Microbiol Resour Announc 2020 Nov 5;9(45). Epub 2020 Nov 5.

Huhehaote Customs District P.R. China, Hohhot, China

To explore the genetic diversity of strains in Erenhot, China, and their relationship with Mongolian strains, we collected and sequenced three strains from Erenhot, China, in 2018. Here, we report the draft genome sequences of three bv. Medievalis strains belonging to the 2.MED phylogroup that were circulating in populations.
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http://dx.doi.org/10.1128/MRA.01084-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7645668PMC
November 2020

Downregulation of miR‑181b inhibits human colon cancer cell proliferation by targeting CYLD and inhibiting the NF‑κB signaling pathway.

Int J Mol Med 2020 Nov 4;46(5):1755-1764. Epub 2020 Sep 4.

Department of Oncology, Dongying People's Hospital, Dongying, Shandong 257091, P.R. China.

It has been reported that microRNA (miRNA/miR)‑181b plays an important role in regulating cellular proliferation, invasion and apoptosis in various tumors. However, the role of miR‑181b and its molecular mechanisms in colon cancer cells have not yet been elucidated. The present study thus aimed to investigate the mechanisms of miR‑181b targeting cylindromatosis (CYLD) to regulate the nuclear factor‑κB (NF‑κB) signaling pathway, and to determine its role in colon cancer cell proliferation and apoptosis. For this purpose, miR‑181b was overexpressed and silenced in the SW480 cell line. The cell proliferation and apoptotic rates were determined using a Cell Counting kit and colony formation assays, and Annexin V‑FITC staining, respectively. The expression levels of proteins associated with the NF‑κB signaling pathway and apoptosis were detected by western blot analysis. Furthermore, a dual luciferase assay was applied to confirm the interaction between miR‑181b and CYLD. CYLD was also overexpressed and silenced in the SW480 cell line using a CYLD overexpression plasmid and siRNA technology, respectively. Transfected cells were used for subsequent experiments. In addition, a nude mouse model was established to measure tumor volume and weight. Immunohistochemistry and a TUNEL assay were performed to detect the Ki67 levels and the cell apoptotic rate, respectively. Compared with the control group, miR‑181 silencing or CYLD overexpression significantly attenuated cell proliferation, invasion and migration, and notably increased the proportion of apoptotic cells. Furthermore, the expression levels of Bax and cleaved caspase‑3 were markedly increased, whereas those of Bcl‑2 were significantly decresaed (P<0.05). In addition, the protein expression levels of p‑p65/p65 and p‑IκBα/IκBα were significantly downregulated and upregulated, respectively (P<0.05). Consistent with the results obtained in vitro, in vivo experiments using a nude mouse model yielded similar findings. The aforementioned results indicated that miR‑181b downregulation inhibited human colon cancer cell proliferation by targeting CYLD to attenuate the activity of the NF‑κB signaling pathway.
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http://dx.doi.org/10.3892/ijmm.2020.4720DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7521473PMC
November 2020

Transition metal-containing molecular devices: controllable single-spin negative differential thermoelectric resistance effects under gate voltages.

Phys Chem Chem Phys 2019 Feb;21(9):5243-5252

College of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu 215500, China.

Based on the non-equilibrium Green function method combined with density functional theory, we investigate the spin-resolved transport through transition metal (TM) (= Cr, Mn, Fe and Ru)-containing molecular devices in the presence of zigzag graphene nanoribbon (ZGNR) electrodes. The wave-function mismatch for the single-spin component results in a perfect spin-filtering property near the Fermi level. Moreover, we also observe Fano and Breit-Wigner resonance peaks in the transmission spectrum. Under a temperature gradient, the single-spin electric current exhibits a remarkable negative differential thermoelectric resistance (NDTR) in the Ru-complex molecular device, which originates from the Fano asymmetry of the single-spin transmission peak near the Fermi level. A gate voltage allows for a precise control of the single-spin NDTR in the Ru-complex molecular device.
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http://dx.doi.org/10.1039/c8cp07049kDOI Listing
February 2019

Metal-Free Half-Metallicity in B-Doped gh-CN Systems.

Nanoscale Res Lett 2018 Feb 20;13(1):57. Epub 2018 Feb 20.

Jiangsu Laboratory of Advanced Functional Materials, College of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu, Jiangsu, 215500, China.

Half-metallicity rising from the s/p electrons has been one of the hot topics in spintronics. Based on the first-principles of calculation, we explore the magnetic properties of the B-doped graphitic heptazine carbon nitride (gh-CN) system. Ferromagnetism is observed in the B-doped gh-CN system. Interestingly, its ground state phase ([email protected]) presents a strong half-metal property. Furthermore, the half-metallicity in [email protected] can sustain up to 5% compressive strain and 1.5% tensile strain. It will lose its half-metallicity, however, when the doping concentration is below 6.25%. Our results show that such a metal-free half-metallic system has promising spintronic applications.
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http://dx.doi.org/10.1186/s11671-018-2473-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5820242PMC
February 2018

A Novel Pruning Algorithm for Smoothing Feedforward Neural Networks Based on Group Lasso Method.

IEEE Trans Neural Netw Learn Syst 2018 05 26;29(5):2012-2024. Epub 2017 Sep 26.

In this paper, we propose four new variants of the backpropagation algorithm to improve the generalization ability for feedforward neural networks. The basic idea of these methods stems from the Group Lasso concept which deals with the variable selection problem at the group level. There are two main drawbacks when the Group Lasso penalty has been directly employed during network training. They are numerical oscillations and theoretical challenges in computing the gradients at the origin. To overcome these obstacles, smoothing functions have then been introduced by approximating the Group Lasso penalty. Numerical experiments for classification and regression problems demonstrate that the proposed algorithms perform better than the other three classical penalization methods, Weight Decay, Weight Elimination, and Approximate Smoother, on both generalization and pruning efficiency. In addition, detailed simulations based on a specific data set have been performed to compare with some other common pruning strategies, which verify the advantages of the proposed algorithm. The pruning abilities of the proposed strategy have been investigated in detail for a relatively large data set, MNIST, in terms of various smoothing approximation cases.
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http://dx.doi.org/10.1109/TNNLS.2017.2748585DOI Listing
May 2018

Triple shape memory effect of star-shaped polyurethane.

ACS Appl Mater Interfaces 2014 May 5;6(9):6545-54. Epub 2014 May 5.

Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University , Chengdu 610031, P.R. China.

In this study, we synthesized one type of star-shaped polyurethane (SPU) with star-shaped poly(ε-caprolactone) (SPCL) containing different arm numbers as soft segment and 4,4'-diphenyl methane diisocyanate (MDI) as well as chain extender 1,4-butylene glycol (BDO) as hard segment. Proton nuclear magnetic resonance (1H-NMR) confirmed the chemical structure of the material. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) results indicated that both the melting temperature (Tm) and transition temperature (Ttrans) of SPU decreased with the hard segment composition increase. X-ray diffraction (XRD) results demonstrated that the increase of the crystallinity of SPU following the raised arm numbers endowed a high shape fixity of six-arm star-shaped polyurethane (6S-PU) and a wide melting temperature range, which resulted in an excellent triple-shape memory effect of 6S-PU. The in vitro cytotoxicity assay evaluated with osteoblasts through Alamar blue assay demonstrates that this copolymer possessed good cytocompatibility. This material can be potentially used as a new smart material in the field of biomaterials.
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http://dx.doi.org/10.1021/am5001344DOI Listing
May 2014

Design of triple-shape memory polyurethane with photo-cross-linking of cinnamon groups.

ACS Appl Mater Interfaces 2013 Nov 17;5(21):10520-8. Epub 2013 Oct 17.

Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University , Chengdu 610031, P.R. China.

A triple-shape memory polyurethane (TSMPU) with poly(ε-caprolactone) -diols (PCL-diols) as the soft segments and diphenyl methane diisocyanate (MDI), N,N-bis (2-hydroxyethyl) cinnamamide (BHECA) as the hard segments was synthesized via simple photo-crosslinking of cinnamon groups irradiated under λ > 280 nm ultraviolet (UV) light. Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance ((1)H-NMR) and ultraviolet-visible absorption spectrum (UV-vis) confirmed the chemical structure of the material. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) results demonstrated that the photo-crosslinked polymer possessed two transition temperatures, one is due to the melting point of the soft segment PCL-diols, and the other is due to the glass transition temperature. All these contributed to the cross-linked structure of the hard segments and resulted in an excellent triple-shape memory effect. Alamar blue assay showed that the material has good non-cytotoxicity and can be potentially used in biomaterial devices.
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http://dx.doi.org/10.1021/am402091mDOI Listing
November 2013

MUC1 glycopeptide epitopes predicted by computational glycomics.

Int J Oncol 2012 Dec 27;41(6):1977-84. Epub 2012 Sep 27.

Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.

Bioinformatic tools and databases for glycobiology and glycomics research are playing increasingly important roles in functional studies. However, to verify hypotheses generated by computational glycomics with empirical functional assays is only an emerging field. In this study, we predicted glycan epitopes expressed by a cancer-derived mucin, MUC1, by computational glycomics. MUC1 is expressed by tumor cells with a deficiency in glycosylation. Although numerous diagnostic reagents and cancer vaccines have been designed based on abnormally glycosylated MUC1 sequences, the glycan and peptide sequences responsible for immune responses in vivo are poorly understood. The immunogenicity of synthetic MUC1 glycopeptides bearing Tn or sialyl-Tn antigens have been studied in mouse models, while authentic glyco-epitopes expressed by tumor cells remain unclear. To examine the immunogenicity of authentic cancer derived MUC1 glyco-epitopes, we expressed membrane bound forms of MUC1 tandem repeats in Jurkat, a mutant cancer cell line deficient of mucin-type core-1 β1-3 galactosyltransferase activity, and immunized mice with cancer cells expressing authentic MUC1 glyco-epitopes. Antibody responses to individual glyco-epitopes were determined by chemically synthesized candidate MUC1 glycopeptides predicted through computational glycomics. Monoclonal antibodies can be generated toward chemically synthesized glycopeptide sequences. With RPAPGS(Tn)TAPPAHG as an example, a monoclonal antibody 16A, showed 25-fold higher binding to glycosylated peptide (EC50=9.278±1.059 ng/ml) compared to its non-glycosylated form (EC(50)=247.3±16.29 ng/ml) as measured by ELISA experiments with plate-bound peptides. A library of monoclonal antibodies toward authentic MUC1 glycopeptide epitopes may be a valuable tool for studying glycan and peptide sequences in cancer, as well as reagents for diagnosis and therapy.
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http://dx.doi.org/10.3892/ijo.2012.1645DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3556481PMC
December 2012

A rapid detection method for apoptosis and necrosis measurement using the Cellometer imaging cytometry.

Apoptosis 2011 Dec;16(12):1295-303

Department of Technology R&D, Nexcelom Bioscience LLC, Lawrence, MA 01843, USA.

Apoptosis and necrosis play an important role in various aspects of preclinical pharmaceutical drug discovery and validation. The ability to quickly determine the cytotoxic effect of chemical compounds on cancer cells allows researchers to efficiently identify potential drug candidates for further development in the pharmaceutical discovery pipeline. Recently, a new imaging cytometry system has been developed by Nexcelom Bioscience LLC (Lawrence, MA, USA) for fluorescence-based cell population analysis. Currently, fluorescence-based cell death assays have not been demonstrated by the Cellometer system, which can potentially provide a quick, simple, and inexpensive alternative method for smaller biomedical research laboratories. In this study, we demonstrate for the first time the use of Cellometer imaging cytometry for necrosis/apoptosis detection by studying the dose-response effect of heat and drug-induced cell death in Jurkat cells labeled with annexin V-FITC (apoptotic) and propidium iodide (necrotic). The experimental results were evaluated to validate the imaging cytometric capabilities of the Cellometer system as compared to the conventional flow cytometry. Similar cell population results were obtained from the two methods. The ability of Cellometer to rapidly and cost-effectively perform fluorescent cell-based assays has the potential of improving research efficiency, especially where a flow or laser scanning cytometer is not available or in situations where a rapid analysis of data is desired.
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http://dx.doi.org/10.1007/s10495-011-0651-8DOI Listing
December 2011

CD molecules 2006--human cell differentiation molecules.

J Immunol Methods 2007 Jan 4;319(1-2):1-5. Epub 2006 Dec 4.

Child Health Research Institute and Adelaide University Discipline of Paediatrics, 72 King William Road, North Adelaide, South Australia 5006, Australia.

The Human Leucocyte Differentiation Antigens Workshops (HLDA) have since 1984 provided a forum for the characterization and study of leucocyte surface molecules and antibodies against them. HLDA devised the CD nomenclature, which is sanctioned by IUIS. The HLDA Council reviewed and modified the objectives of HLDA in 2004, and changed the name of the organization to Human Cell Differentiation Molecules (HCDM) to reflect the broader objectives. Workshop studies under the HCDM banner proceeded during 2005 and early 2006, culminating in a meeting in May 2006. At that meeting the Council, acting as Nomenclature Committee, approved a number of new CD designations and changes to some pre-existing CD designations, which are summarized in this report.
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http://dx.doi.org/10.1016/j.jim.2006.11.001DOI Listing
January 2007

Dispersion of linearly polarized light propagating in a thin birefringent plate.

J Opt Soc Am A Opt Image Sci Vis 2005 Apr;22(4):752-9

Institute of Modern Optics Nankai University, Key Laboratory of Opto-electronic Information Science and Technology, Education Ministry of China, Tianjin 300071, China.

We analyze theoretically the dispersion of linearly polarized light propagating in a uniaxial anisotropic medium where multibeam interference is present. Explicit expressions of the group-delay dispersion for transmitting waves are derived for the simplest situation, and the effect of dispersion on pulse broadening is analyzed for a few selected cases. Our results reveal that at normal incidence and in the situation where the optic axis is parallel to the surface of birefringent plate (in the x-y plane), the dispersion of the refracted wave decreases with the extent of birefringence. In particular, the dispersion for the electric field parallel to the polarization direction of the incident light changes with the rotation angle between the optic axis and the polarization direction of the incident field, whereas the dispersion for the refracted field whose direction is vertical to the polarization of incident light is independent of this angle. For oblique incidence, dispersion varies substantially for different incident angles. In the situation where the optic axis is in the x-z plane at either normal or oblique incidence, the dispersion increases in a periodically oscillating manner as a function of the relative thickness of the birefringent plate.
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http://dx.doi.org/10.1364/josaa.22.000752DOI Listing
April 2005
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