Publications by authors named "Letian Wang"

39 Publications

Early dynamics of cavitation bubbles generated during ns laser ablation of submerged targets.

Opt Express 2020 May;28(10):14300-14309

In this study, we observe and study the early evolution of cavitation bubbles generated during pulsed laser ablation of titanium targets in different liquid environments utilizing a high-resolution stroboscopic shadowgraphy system. A hydrodynamic model is proposed to calculate the early pressure changes within the bubble and in the surrounding fluid. Our results show that the cavitation bubble is a low-pressure region that is bounded by a high-pressure fluid lamina after the incipient stage, and its evolution is primarily affected by the liquid density. Moreover, the initial bubble pressure increases substantially in high viscosity liquids. This work illuminates how the liquid properties affect the early bubble dynamics and is a step towards a deeper understanding of laser-materials interactions in liquid environments.
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http://dx.doi.org/10.1364/OE.391584DOI Listing
May 2020

Fabrication of flexible transparent Ag square-shaped mesh electrode by top-flat nanosecond laser ablation.

Opt Lett 2020 Feb;45(4):901-904

We report a facile top-flat square nanosecond (ns) laser direct writing ablation technique in a thin silver film substrate to fabricate the silver square-shaped cell structure of flexible transparent electrodes. Square silver cell structures feature smooth surface morphology, excellent edge definition, mechanical stability, strong adhesion to the substrate, and favorable resistance and transparency. In particular, this strategy enables fabrication of a high square-shaped cell areal density (ablated square cell to the total area) Ag mesh, substantially improving transparency ($ {\gt} {85}\% $>85%) without considerably sacrificing conductivity ($ {\lt} {5}\;\Omega \;{{\rm sq}^{ - 1}}$<5Ωsq unit of resistance). Consequently, the proposed metallic square-shaped structure shows compatibility with a polyethylene naphthalate flexible substrate for silver-based wearable electronic devices without any protective layer over the electrodes.
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http://dx.doi.org/10.1364/OL.384463DOI Listing
February 2020

Design and validation of a ten nanosecond resolved resistive thermometer for Gaussian laser beam heating.

Rev Sci Instrum 2019 Dec;90(12):124903

Laser Thermal Laboratory, Department of Mechanical Engineering, University of California, Berkeley, Berkeley, California 94720-1740, USA.

Pulsed laser processing plays a crucial role in additive manufacturing and nanomaterial processing. However, probing the transient temperature field during the pulsed laser interaction with the processed materials is challenging as it requires both high spatial and temporal resolution. Previous transient thermometry studies have measured neither sub-100 µm spatial resolution nor sub-10 ns temporal resolution. The temperature field induced by Gaussian laser beam profiles has also not been accounted for. Here, we demonstrate a 9 ns rise time, 50 µm sized Pt thin-film sensor for probing the temperature field generated by a nanosecond pulsed laser on a semiconductor thin film. The measurement error sources and associated improvements in the thin film fabrication, sensor patterning, and electrical circuitry are discussed. We carried out the first experimental and theoretical analysis of spatial resolution and accuracy for measuring a Gaussian pulse on the serpentine structure. Transparent silica and sapphire substrates, as well as 7-45 nm insulation layer thicknesses, are compared for sensing accuracy and temporal resolution. Finally, the measured absolute temperature magnitude is validated through the laser-induced melting of the 40 nm thick amorphous silicon film. Preliminary study shows its potential application for probing heat conduction among ultrathin films.
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http://dx.doi.org/10.1063/1.5118811DOI Listing
December 2019

Bimodal Molecule as NIR-CT Contrast Agent for Hepatoma Specific Imaging.

Anal Chem 2020 01 20;92(1):1138-1146. Epub 2019 Dec 20.

School of Basic Medicine and Clinical Pharmacology , China Pharmaceutical University , Nanjing 211100 , China.

With currently available molecular imaging techniques, hepatocellular carcinoma (HCC), a liver cancer with high mortality rates and poor treatment responses, is mostly diagnosed at its late stage. This is largely due to the lack of highly sensitive contrast agents with high liver specificity. Herein, we report a novel bimodal contrast agent molecule CNCI-1 for the effective detection of HCC at its early stage both in vitro and in vivo. The agent has high liver specificity with effective X-ray computed tomography (CT)/near-infrared (NIR) imaging functions. It has been successfully applied to in vivo NIR imaging with high sensitivity and high selectivity to the HCC region of the HepG2 tumor-xenografted mice model and LM3 orthotopic hepatoma mice model. Moreover, the agent was found to be noninvasive and hepatocarcinoma cells preferential. Furthermore, it also enhanced the tumor imaging by revealing the blood vessels nearby for the CT image acquisition in the VX2 orthotopic hepatoma rabbit model. Our design strategy provides a new avenue to develop the medical relevant bimodal contrast agents for diagnosis of HCC at its early stage.
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http://dx.doi.org/10.1021/acs.analchem.9b04212DOI Listing
January 2020

High-Speed Photothermal Patterning of Doped Polymer Films.

ACS Appl Mater Interfaces 2019 Nov 25;11(44):41717-41725. Epub 2019 Oct 25.

Department of Mechanical Engineering , University of California , Berkeley , 94720 California , United States.

Organic semiconductors (OSCs) offer a new avenue to the next-generation electronics, but the lack of a scalable and inexpensive nanoscale patterning/deposition technique still limits their use in electronic applications. Recently, a new lithographic etching technique has been introduced that uses molecular dopants to reduce semiconducting polymer solubility in solvents and a direct-write laser to remove dopants locally, enabling rapid OSC etching with diffraction limited resolution. Previous publications postulated that the reaction that enables patterning is a photochemical reaction between photoexcited dopants with neutral solvent molecules. In this work, we analyze the photoinduced dissolution kinetics of F4TCNQ doped P3HT films using time-resolved in situ optical probing. We find two competing mechanisms that control de-doping and dissolution: the first is the photochemical reaction posited in the literature, and the second involves direct heating of the polymer by the laser, inducing increased solubility for both the polymer and dopant. We show that the wavelength-specific photochemical effect is dominant in low photon doses while the photothermal effect is dominant with high excitation rates regardless of laser wavelength. With sufficiently high optical intensity input, the photothermal mechanism can in principle achieve a high writing speed up to 1 m/s. Our findings bring new insights into the mechanisms behind laser direct writing of OSCs based on dopant induced solubility control and enable ultraprecise fabrications of various device configurations in large-scale manufacturing.
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http://dx.doi.org/10.1021/acsami.9b15860DOI Listing
November 2019

Site-Selective Atomic Layer Precision Thinning of MoS via Laser-Assisted Anisotropic Chemical Etching.

ACS Appl Mater Interfaces 2019 Oct 8;11(42):39385-39393. Epub 2019 Oct 8.

Laser Thermal Lab, Department of Mechanical Engineering , University of California , Berkeley , California 94720 , United States.

Various exotic optoelectronic properties of two-dimensional (2D) transition metal dichalcogenides (TMDCs) strongly depend on their number of layers, and typically manifest in ultrathin few-layer or monolayer formats. Thus, precise manipulation of thickness and shape is essential to fully access their potential in optoelectronic applications. Here, we demonstrate site-selective atomic layer precision thinning of exfoliated MoS flake by laser. The oxidation mediated anisotropic chemical etching initiated from edge defects and progressed by controlled scanning of the laser beam. Thereby, the topmost layer can be preferentially removed in designed patterns without damaging the bottom flake. In addition, we could monitor the deceleration of the thinning by in situ reflectance measurement. The apparent slow down of the thinning rate is attributed to the sharp reduction in the temperature of the flake due to thickness dependent optical properties. Fabrication of monolayer stripes by laser thinning suggests potential applications in nonlinear optical gratings. The proposed thinning method would offer a unique and rather straightforward way to obtain arbitrary shape and thickness of a TMDCs flake for various optoelectronic applications.
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http://dx.doi.org/10.1021/acsami.9b14306DOI Listing
October 2019

Feasibility Study of Single-Crystal Si Island Manufacturing by Microscale Printing of Nanoparticles and Laser Crystallization.

ACS Appl Mater Interfaces 2019 Sep 5;11(37):34416-34423. Epub 2019 Sep 5.

Department of Mechanical and Aerospace Engineering , Missouri University of Science and Technology , Rolla , Missouri 65409 , United States.

Nonvacuum printing of single crystals would be ideal for high-performance functional device (such as electronics) fabrication yet challenging for most materials, especially for inorganic semiconductors. Currently, the printed films are dominant in amorphous, polycrystalline, or nanoparticle films. In this article, manufacturing of single-crystal silicon micro/nano-islands is attempted. Different from traditional vapor deposition for silicon thin-film preparation, silicon nanoparticle ink was aerosol-printed followed by confined laser melting and crystallization, allowing potential fabrication of single-crystal silicon micro/nano-islands. It is also shown that as-fabricated Si islands can be transfer-printed onto polymer substrates for potential application of flexible electronics. The additive nature of this technique suggests a scalable and economical approach for high-crystallinity semiconductor printing.
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http://dx.doi.org/10.1021/acsami.9b09577DOI Listing
September 2019

The beneficial effects of rutin on myofibrillar protein gel properties and related changes in protein conformation.

Food Chem 2019 Dec 18;301:125206. Epub 2019 Jul 18.

College of Food Science and Technology, Bohai University, National & Local Joint Engineering Research Center of Storage, Jinzhou, Liaoning 121013, China. Electronic address:

Effects of different levels of rutin (0, 10, 50, 100 and 200 μmol/g protein) on the conformational changes and gel properties of myofibrillar protein (MP) were investigated. Rutin at 200 μmol/g caused the greatest carbonyl content. The incorporation of rutin caused the losses of thiol, free amine and α-helix contents, reduction in tryptophan intrinsic fluorescence intensity, and enhanced exposure of hydrophobic groups and protein cross-linking. When compared with control, the MP gels with 10, 50 and 100 μmol/g rutin had higher gel strength but slight lower water-holding capacity; the gels appeared to have compact microstructure with few visible pores. However, 200 μmol/g rutin was detrimental to gel properties. All the gels with rutin presented higher final storage modulus and converted to elasticity-dominant gel types. The results indicate that a slightly high concentration of rutin could improve MP gel properties which are related to the protein conformational changes induced by rutin.
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http://dx.doi.org/10.1016/j.foodchem.2019.125206DOI Listing
December 2019

Synthesis of water soluble and multi-responsive selenopolypeptides via ring-opening polymerization of N-carboxyanhydrides.

Chem Commun (Camb) 2019 Jul;55(54):7860-7863

Beijing National Laboratory for Molecular Sciences, Center for Soft Matter Science and Engineering, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China.

We report here the synthesis of water soluble selenopolypeptides via the ring-opening polymerization of N-carboxyanhydrides. The oligoethylene glycol-bearing selenopolypeptides are thermally responsive in aqueous solutions with tunable lower critical solution temperatures. The polymers can also undergo rapid and reversible helix-coil transitions upon responding to the added redox cycle.
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http://dx.doi.org/10.1039/c9cc03767eDOI Listing
July 2019

In situ and ex-situ physical scenario of the femtosecond laser-induced periodic surface structures.

Opt Express 2019 Apr;27(7):10087-10097

Laser-induced periodic surface structures (LIPSS) are a universal phenomenon that can allow tailoring nanoelectronics and nanophotonics devices. However, there is an issue about the formation mechanism of LIPSS, and the current research mainly focuses on the formation process of the individual structures, such as the low spatial frequency LIPSS (LSFL), sub-wavelength structures, and laser-induced periodic annular surface structures (LIPASS). A whole process formation picture of the series of these periodic structures is still missing. In this study, a pump-probing setup is applied to ensure the real-time and in situ monitoring of surface modification under different pulse numbers. LSFL firstly appears on the surface after two laser shots, and then, laser-induced orthogonal periodic structures (LIOPS) become the dominant morphology after five laser shots, which result from the local field enhancement of the surface ripples. As the laser shots increase, the LSFL split leads to the formation of nanopillars, and the formation of the nanopillars under the surface LSFL (after ten laser shots) is due to the transition between the LSFL and HSFL with an orientation parallel to the laser polarization. A dip surrounded by annular periodic fringes after 50 laser shots is observed, which is due to the interference of the incident laser field and the reflected laser field on the crater surface. Finally, a direct writing technique for fabrication of nano-gratings is also reported.
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http://dx.doi.org/10.1364/OE.27.010087DOI Listing
April 2019

RNA Sequencing Reveals the Suitability of Cardiac Death Livers for Transplantation.

Biomed Res Int 2018 1;2018:8217486. Epub 2018 Nov 1.

Institute of Liver Transplantation, General Hospital of Chinese People's Armed Police Force, Beijing, China.

Background: Organ transplantation is considered the best treatment for end-stage organ failure. However, the lack of available organs for transplantation and the increasing number of patients waiting for transplants are primary issues facing the transplant community. Thus, developing strategies to increase the number of donors, especially for liver transplantation, has become a priority. The use of organs acquired from donors who suffered cardiac related deaths has increased the pool of potential liver donors. However, donation after cardiac death (DCD) livers increases the risk of primary graft dysfunction.

Methods: In the current study, we conducted transcriptome sequencing using livers from a DCD rat to assess the short-term feasibility and functional efficacy of DCD livers. RNA sequencing (RNAseq) data showed that the liver transcriptome varied greatly in rat livers subjected to 15 minutes of cardiac arrest.

Results: The livers used in the current study had a significant loss of normal function before transplantation. Functional and network analyses consistently indicated that transcription and translation processes were inhibited after approximately 15 minutes of cardiac arrest. Moreover, the transcriptomic sequencing data provides significant insight for identifying functional genes and testing additional biological questions in DCD liver transplantation in future studies.
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http://dx.doi.org/10.1155/2018/8217486DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6241343PMC
March 2019

Combined caveolin-1 and epidermal growth factor receptor expression as a prognostic marker for breast cancer.

Oncol Lett 2018 Jun 18;15(6):9271-9282. Epub 2018 Apr 18.

Department of Pathology, The Third Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China.

Previous studies have indicated that caveolin-1 (Cav-1) is able to bind the signal transduction factor epidermal growth factor receptor (EGFR) to regulate its tyrosine kinase activity. The aim of the present study was to evaluate the clinical significance of Cav-1 gene expression in association with the expression of EGFR in patients with breast cancer. Primary breast cancer samples from 306 patients were analyzed for Cav-1 and EGFR expression using immunohistochemistry, and clinical significance was assessed using multivariate Cox regression analysis, Kaplan-Meier estimator curves and the log-rank test. Stromal Cav-1 was downregulated in 38.56% (118/306) of tumor tissues, whereas cytoplasmic EGFR and Cav-1 were overexpressed in 53.92% (165/306) and 44.12% (135/306) of breast cancer tissues, respectively. EGFR expression was positively associated with cytoplasmic Cav-1 and not associated with stromal Cav-1 expression in breast cancer samples; however, low expression of stromal Cav-1 was negatively associated with cytoplasmic Cav-1 expression in total tumor tissues, and analogous results were identified in the chemotherapy group. Multivariate Cox's proportional hazards model analysis revealed that, for patients in the estrogen receptor (ER)(+) group, the expression of stromal Cav-1 alone was a significant prognostic marker of breast cancer. However, in the chemotherapy, human epidermal growth factor receptor 2 (HER-2)(-), HER-2(+) and ER(-) groups, the use of combined markers was more effective prognostic marker. Stromal Cav-1 has a tumor suppressor function, and the combined marker stromal Cav-1/EGFR expression was identified as an improved prognostic marker in the diagnosis of breast cancer. Parenchymal expression of Cav-1 is able to promote EGFR signaling in breast cancer, potentially being required for EGFR-mediated initiation of mitosis.
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http://dx.doi.org/10.3892/ol.2018.8533DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5958698PMC
June 2018

Pulse laser-induced size-controllable and symmetrical ordering of single-crystal Si islands.

Nanoscale 2018 May;10(17):8133-8138

Laboratory of Infrared Materials and Devices, The Research Institute of Advanced Technologies, Ningbo University, Ningbo, Zhejiang 315211, People's Republic of China.

Optically electric- and magnetic resonance-induced dielectric nanostructures have garnered significant attention due to applications as tunable electronic and optoelectronic device. In this letter, we describe an ultrafast and large-area method to construct symmetrical and single-crystal Si island structures directly on Si substrates by a pulse laser dewetting method. The tunable surface electric field intensity distribution could convert the stochastic dewetting process into a deterministic process (classical dipole mode and Mie resonance dipole mode) on predefined Si pit arrays via laser dewetting. Under this condition, these pre-patterned Si substrate structures not only induced high spatial ordering of islands, but also improved their size uniformity. By adjusting the laser fluence, the diameter of the single-crystal Si islands could be selected in the range 41.7-147.1 nm.
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http://dx.doi.org/10.1039/c8nr00210jDOI Listing
May 2018

Programming Nanoparticles in Multiscale: Optically Modulated Assembly and Phase Switching of Silicon Nanoparticle Array.

ACS Nano 2018 03 26;12(3):2231-2241. Epub 2018 Feb 26.

Laser Thermal Laboratory, Department of Mechanical Engineering , University of California , Berkeley , California 94720-1740 , United States.

Manipulating and tuning nanoparticles by means of optical field interactions is of key interest for nanoscience and applications in electronics and photonics. We report scalable, direct, and optically modulated writing of nanoparticle patterns (size, number, and location) of high precision using a pulsed nanosecond laser. The complex nanoparticle arrangement is modulated by the laser pulse energy and polarization with the particle size ranging from 60 to 330 nm. Furthermore, we report fast cooling-rate induced phase switching of crystalline Si nanoparticles to the amorphous state. Such phase switching has usually been observed in compound phase change materials like GeSbTe. The ensuing modification of atomic structure leads to dielectric constant switching. Based on these effects, a multiscale laser-assisted method of fabricating Mie resonator arrays is proposed. The number of Mie resonators, as well as the resonance peaks and dielectric constants of selected resonators, can be programmed. The programmable light-matter interaction serves as a mechanism to fabricate optical metasurfaces, structural color, and multidimensional optical storage devices.
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http://dx.doi.org/10.1021/acsnano.8b00198DOI Listing
March 2018

A 0.2 V Micro-Electromechanical Switch Enabled by a Phase Transition.

Small 2018 04 26;14(14):e1703621. Epub 2018 Feb 26.

Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.

Micro-electromechanical (MEM) switches, with advantages such as quasi-zero leakage current, emerge as attractive candidates for overcoming the physical limits of complementary metal-oxide semiconductor (CMOS) devices. To practically integrate MEM switches into CMOS circuits, two major challenges must be addressed: sub 1 V operating voltage to match the voltage levels in current circuit systems and being able to deliver at least millions of operating cycles. However, existing sub 1 V mechanical switches are mostly subject to significant body bias and/or limited lifetimes, thus failing to meet both limitations simultaneously. Here 0.2 V MEM switching devices with ≳10 safe operating cycles in ambient air are reported, which achieve the lowest operating voltage in mechanical switches without body bias reported to date. The ultralow operating voltage is mainly enabled by the abrupt phase transition of nanolayered vanadium dioxide (VO ) slightly above room temperature. The phase-transition MEM switches open possibilities for sub 1 V hybrid integrated devices/circuits/systems, as well as ultralow power consumption sensors for Internet of Things applications.
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http://dx.doi.org/10.1002/smll.201703621DOI Listing
April 2018

A Lithography-Free and Field-Programmable Photonic Metacanvas.

Adv Mater 2018 Feb 11;30(5). Epub 2017 Dec 11.

Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.

The unique correspondence between mathematical operators and photonic elements in wave optics enables quantitative analysis of light manipulation with individual optical devices. Phase-transition materials are able to provide real-time reconfigurability of these devices, which would create new optical functionalities via (re)compilation of photonic operators, as those achieved in other fields such as field-programmable gate arrays (FPGA). Here, by exploiting the hysteretic phase transition of vanadium dioxide, an all-solid, rewritable metacanvas on which nearly arbitrary photonic devices can be rapidly and repeatedly written and erased is presented. The writing is performed with a low-power laser and the entire process stays below 90 °C. Using the metacanvas, dynamic manipulation of optical waves is demonstrated for light propagation, polarization, and reconstruction. The metacanvas supports physical (re)compilation of photonic operators akin to that of FPGA, opening up possibilities where photonic elements can be field programmed to deliver complex, system-level functionalities.
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http://dx.doi.org/10.1002/adma.201703878DOI Listing
February 2018

Increased Eps15 homology domain 1 and RAB11FIP3 expression regulate breast cancer progression via promoting epithelial growth factor receptor recycling.

Tumour Biol 2017 Feb;39(2):1010428317691010

3 Kashkin Research Institute of Medical Mycology, I.I. Mechnikov North-Western State Medical University, Saint Petersburg, Russia.

Recent research indicates that the C-terminal Eps15 homology domain 1 is associated with epithelial growth factor receptor-mediated endocytosis recycling in non-small-cell lung cancer. The aim of this study was to determine the clinical significance of Eps15 homology domain 1 gene expression in relation to phosphorylation of epithelial growth factor receptor expression in patients with breast cancer. Primary breast cancer samples from 306 patients were analyzed for Eps15 homology domain 1, RAB11FIP3, and phosphorylation of epithelial growth factor receptor expression via immunohistochemistry. The clinical significance was assessed via a multivariate Cox regression analysis, Kaplan-Meier curves, and the log-rank test. Eps15 homology domain 1 and phosphorylation of epithelial growth factor receptor were upregulated in 60.46% (185/306) and 53.92% (165/306) of tumor tissues, respectively, as assessed by immunohistochemistry. The statistical correlation analysis indicated that Eps15 homology domain 1 overexpression was positively correlated with the increases in phosphorylation of epithelial growth factor receptor ( r = 0.242, p < 0.001) and RAB11FIP3 ( r = 0.165, p = 0.005) expression. The multivariate Cox proportional hazard model analysis demonstrated that the expression of Eps15 homology domain 1 alone is a significant prognostic marker of breast cancer for the overall survival in the total, chemotherapy, and human epidermal growth factor receptor 2 (-) groups. However, the use of combined expression of Eps15 homology domain 1 and phosphorylation of epithelial growth factor receptor markers is more effective for the disease-free survival in the overall population, chemotherapy, and human epidermal growth factor receptor 2 (-) groups. Moreover, the combined markers are also significant prognostic markers of breast cancer in the human epidermal growth factor receptor 2 (+), estrogen receptor (+), and estrogen receptor (-) groups. Eps15 homology domain 1 has a tumor suppressor function, and the combined marker of Eps15 homology domain 1/phosphorylation of epithelial growth factor receptor expression was identified as a better prognostic marker in breast cancer diagnosis. Furthermore, RAB11FIP3 combines with Eps15 homology domain 1 to promote the endocytosis recycling of phosphorylation of epithelial growth factor receptor.
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http://dx.doi.org/10.1177/1010428317691010DOI Listing
February 2017

Design, synthesis and biological evaluation of novel non-peptide boronic acid derivatives as proteasome inhibitors.

Eur J Med Chem 2017 Mar 23;128:180-191. Epub 2017 Jan 23.

Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China; Department of Medicinal Chemistry, China Pharmaceutical University, Nanjing 210009, China. Electronic address:

A novel series of non-peptide proteasome inhibitors bearing the 1, 4-naphthoquinone scaffold and boronic acid warhead was developed. In the biological evaluation on the chymotrypsin-like activity of human 20S proteasome, five compounds showed IC values in the nanomolar range. Docking experiments into the yeast 20S proteasome rationalized their biological activities and allowed further optimization of this interesting class of inhibitors. Within the cellular proliferation inhibition assay and western blot analysis, compound 3e demonstrated excellent anti-proliferative activity against solid tumor cells and clear accumulation of ubiquitinated cellular proteins. Furthermore, in the microsomal stability assay compound 3e demonstrated much improved metabolic stability compared to bortezomib, emerging as a promising lead compound for further design of non-peptide proteasome inhibitors.
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http://dx.doi.org/10.1016/j.ejmech.2017.01.034DOI Listing
March 2017

Targeting β-amyloid plaques and oligomers: development of near-IR fluorescence imaging probes.

Future Med Chem 2017 02 27;9(2):179-198. Epub 2017 Jan 27.

Jiangsu Key Laboratory of Drug Design & Optimization, Department of Medicinal Chemistry, China Pharmaceutical University, Nanjing 210009, China.

Evidence indicated that shifting treatment to a presymptomatic stage may produce significant benefits to prevent/alleviate the progression of Alzheimer's disease (AD); in particular, early incorporation of noninvasive imaging and biomarker testing will be significantly beneficial for AD drug development. Based on amyloid cascade hypothesis and its revised version, both β-amyloid deposition and soluble oligomeric species could be good diagnostic biomarkers for AD. Near-IR fluorescence (NIRF) imaging, which so far is limited to animal studies, is a promising method for its incomparable advantages such as low cost, high-throughput and easy operation. This review focuses on recent reported NIRF probes that showed excellent binding to plaques and oligomers. We hope that this review will shed light on the future of NIRF probes' discovery.
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http://dx.doi.org/10.4155/fmc-2016-0185DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6040043PMC
February 2017

Changes in the structural and gel properties of pork myofibrillar protein induced by catechin modification.

Meat Sci 2017 May 16;127:45-50. Epub 2017 Jan 16.

College of Food Science, Northeast Agricultural University, Harbin, Heilongjiang 150030, China. Electronic address:

Different concentrations of catechin (0, 10, 50, 100 and 200μmol/g protein) were added to pork myofibrillar protein (MP) suspensions, and the related changes in protein conformational and gel properties were investigated. The results showed that catechin at 200μmol/g protein led to the greatest increase in the surface hydrophobicity of MP. A significant loss of thiols (SH) content was observed in MP in the presence of catechin. The low concentration of catechin of 10μmol/g led to slight changes in the MP gel strength and water-holding capacity. However, catechin at higher concentrations (50, 100 and 200μmol/g protein) caused severe deterioration of MP gelation. The microstructure and dynamic rheological properties confirmed the unfavorable effect of catechin on the MP gel properties. The results indicate that catechin caused changes in MP conformational and gel properties, which may be due to the catechin-MP covalent interactions and the exposure of hydrophobic domains caused by catechin.
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http://dx.doi.org/10.1016/j.meatsci.2017.01.004DOI Listing
May 2017

Pilot feasibility research of Chinese version of kidney transplant questionnaire in recipients of living donor kidney transplantation.

Int J Clin Exp Med 2015 15;8(12):22570-6. Epub 2015 Dec 15.

Institute of Organ Transplantation, The General Hospital of Chinese People's Armed Police Forces Beijing 100039, China.

Objective: To explore the feasibility of the Chinese version of Kidney Transplant Questionnaire (KTQ) by evaluating the health-related quality of life (HRQoL) in Chinese recipients of living donor kidney transplantation.

Methods: The English version of KTQ was translated into Chinese and underwent cultural adaptation to obtain the Chinese version of KTQ. HRQoL of 136 Chinese recipients of living donor kidney transplantation that met the inclusion criteria were evaluated to assess the validity and reliability of the questionnaire.

Results: One hundred and thirty-six recipients (98 males and 38 females) of living donor kidney transplantation were included. The mean age of the recipients was 43.91 years. For each dimension of the questionnaire, the Cronbach's alpha coefficient was 0.7-0.9, test-retest reliability coefficient ≥0.7, goodness of fit index (GFI) >0.9, and comparative fitness index (CFI) >0.9.

Conclusion: The validity and reliability of the Chinese version of KTQ is similar to the English version, suggesting that the Chinese version of KTQ could be applied as a disease-specific questionnaire to evaluate the HRQoL of the recipients of living donor kidney transplantation in China.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4730030PMC
February 2016

Functional dissection of virus-human crosstalk mediated by miRNAs based on the VmiReg database.

Mol Biosyst 2015 May;11(5):1319-28

College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, China.

Recently, a number of viruses have been shown to encode microRNAs (miRNAs), and they play important roles in several biological processes, enhancing the intricacies of the virus-host crosstalk. However, systematically deciphering the characteristics of crosstalk mediated by viral and human miRNAs has been hampered by the lack of high-confidence targets. Here, a user-friendly platform is developed to provide experimentally validated and predicted target genes of viral miRNAs as well as their functions, named VmiReg. To explore the virus-human crosstalk meditated by miRNAs, validated human cellular targets of viral and cellular miRNAs are analyzed. As a result, target genes of viral miRNAs are prone to be silenced by human miRNAs. Two kinds of targets have globally significantly high functional similarities and are more often found simultaneously in many important biological functions, even in disease genes, particularly cancer genes, and essential genes. In addition, viral and human miRNA targets are in close proximity within the protein-protein interaction network, indicating frequent communication via physical interactions to participate in the same functions. Finally, multiple dense modules intuitively exhibit crosstalk between viral and cellular miRNAs. Furthermore, most co-regulated genes tend to be in important locations of modules. The lymphoma-related module is one of the typical examples. Our study suggests that the functional importance of cellular genes targeted by viral miRNAs and the intricate virus-host crosstalk mediated by miRNAs may be performed via the sharing of target genes or physical interactions, providing a new direction in further researching the roles of miRNAs in infection.
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http://dx.doi.org/10.1039/c5mb00095eDOI Listing
May 2015

RBMS3 is a tumor suppressor gene that acts as a favorable prognostic marker in lung squamous cell carcinoma.

Med Oncol 2015 Feb 15;32(2):459. Epub 2015 Jan 15.

Department of Pathology, Harbin Medical University, Harbin, 150081, China.

Recent research indicates that RBMS3 may act as a tumor suppressor gene (TSG) in nasopharyngeal carcinoma (NPC) and esophageal squamous cell carcinoma (ESCC). It has been reported that RBMS3 directly binds to the promoter region of c-Myc in ESCC and that β-catenin from both whole cell extracts and nuclear fractionation was significantly downregulated in RBMS3-transfected NPC cells compared to control cells. The aim of this study was to evaluate the clinical significance of the RBMS3 gene expression in relation to the expression of Wnt pathway components in patients with lung squamous cell carcinoma (LSCC). RBMS3, c-Myc and cytoplasmic β-catenin were detected in 39.76, 56.63 and 89.16 % of 83 LSCC samples by immunohistochemistry, respectively, in 83 primary LSCC samples. Semiquantitative reverse transcriptase-polymerase chain reaction and Western blotting demonstrated decreased RBMS3 mRNA and expression in 33.33 % (10/30) and 36.67 % (11/30) tumor tissues, respectively. Statistical correlation analysis showed RBMS3 to be negatively correlated with c-Myc (r = -0.384, p < 0.001) and not correlated with cytoplasmic β-catenin in the LSCC samples. Multivariate Cox proportional hazards model analysis showed that the combined marker RBMS3/c-Myc was an independent prognostic indicator of overall survival (p = 0.001; HR 3.470; IC 95 %, 1.652-7.290), and c-Myc was a prognostic indicator of disease-free survival (p < 0.001; HR 3.182; IC 95 %, 1.961-8.920). RBMS3 is a novel TSG in LSCC, and its downregulation facilitates development and progression of LSCC. Therefore, it is suggested that Rbms3 as a tumor marker may play an important role in diagnosis of LSCC.
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http://dx.doi.org/10.1007/s12032-014-0459-9DOI Listing
February 2015

Design and control of the MINDWALKER exoskeleton.

IEEE Trans Neural Syst Rehabil Eng 2015 Mar 30;23(2):277-86. Epub 2014 Oct 30.

Powered exoskeletons can empower paraplegics to stand and walk. Actively controlled hip ab/adduction (HAA) is needed for weight shift and for lateral foot placement to support dynamic balance control and to counteract disturbances in the frontal plane. Here, we describe the design, control, and preliminary evaluation of a novel exoskeleton, MINDWALKER. Besides powered hip flexion/extension and knee flexion/extension, it also has powered HAA. Each of the powered joints has a series elastic actuator, which can deliver 100 Nm torque and 1 kW power. A finite-state machine based controller provides gait assistance in both the sagittal and frontal planes. State transitions, such as stepping, can be triggered by the displacement of the Center of Mass (CoM). A novel step-width adaptation algorithm was proposed to stabilize lateral balance. We tested this exoskeleton on both healthy subjects and paraplegics. Experimental results showed that all users could successfully trigger steps by CoM displacement. The step-width adaptation algorithm could actively counteract disturbances, such as pushes. With the current implementations, stable walking without crutches has been achieved for healthy subjects but not yet for SCI paraplegics. More research and development is needed to improve the gait stability.
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http://dx.doi.org/10.1109/TNSRE.2014.2365697DOI Listing
March 2015

Control of Leg Movements Driven by EMG Activity of Shoulder Muscles.

Front Hum Neurosci 2014 20;8:838. Epub 2014 Oct 20.

Laboratory of Neuromotor Physiology, Santa Lucia Foundation , Rome , Italy.

During human walking, there exists a functional neural coupling between arms and legs, and between cervical and lumbosacral pattern generators. Here, we present a novel approach for associating the electromyographic (EMG) activity from upper limb muscles with leg kinematics. Our methodology takes advantage of the high involvement of shoulder muscles in most locomotor-related movements and of the natural co-ordination between arms and legs. Nine healthy subjects were asked to walk at different constant and variable speeds (3-5 km/h), while EMG activity of shoulder (deltoid) muscles and the kinematics of walking were recorded. To ensure a high level of EMG activity in deltoid, the subjects performed slightly larger arm swinging than they usually do. The temporal structure of the burst-like EMG activity was used to predict the spatiotemporal kinematic pattern of the forthcoming step. A comparison of actual and predicted stride leg kinematics showed a high degree of correspondence (r > 0.9). This algorithm has been also implemented in pilot experiments for controlling avatar walking in a virtual reality setup and an exoskeleton during over-ground stepping. The proposed approach may have important implications for the design of human-machine interfaces and neuroprosthetic technologies such as those of assistive lower limb exoskeletons.
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http://dx.doi.org/10.3389/fnhum.2014.00838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4202724PMC
November 2014

EMG patterns during assisted walking in the exoskeleton.

Front Hum Neurosci 2014 16;8:423. Epub 2014 Jun 16.

Laboratory of Neuromotor Physiology, Santa Lucia Foundation Rome, Italy.

Neuroprosthetic technology and robotic exoskeletons are being developed to facilitate stepping, reduce muscle efforts, and promote motor recovery. Nevertheless, the guidance forces of an exoskeleton may influence the sensory inputs, sensorimotor interactions and resulting muscle activity patterns during stepping. The aim of this study was to report the muscle activation patterns in a sample of intact and injured subjects while walking with a robotic exoskeleton and, in particular, to quantify the level of muscle activity during assisted gait. We recorded electromyographic (EMG) activity of different leg and arm muscles during overground walking in an exoskeleton in six healthy individuals and four spinal cord injury (SCI) participants. In SCI patients, EMG activity of the upper limb muscles was augmented while activation of leg muscles was typically small. Contrary to our expectations, however, in neurologically intact subjects, EMG activity of leg muscles was similar or even larger during exoskeleton-assisted walking compared to normal overground walking. In addition, significant variations in the EMG waveforms were found across different walking conditions. The most variable pattern was observed in the hamstring muscles. Overall, the results are consistent with a non-linear reorganization of the locomotor output when using the robotic stepping devices. The findings may contribute to our understanding of human-machine interactions and adaptation of locomotor activity patterns.
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http://dx.doi.org/10.3389/fnhum.2014.00423DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4058900PMC
July 2014

Inferring novel lncRNA-disease associations based on a random walk model of a lncRNA functional similarity network.

Mol Biosyst 2014 Aug;10(8):2074-81

College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081, PR China.

Accumulating evidence demonstrates that long non-coding RNAs (lncRNAs) play important roles in the development and progression of complex human diseases, and predicting novel human lncRNA-disease associations is a challenging and urgently needed task, especially at a time when increasing amounts of lncRNA-related biological data are available. In this study, we proposed a global network-based computational framework, RWRlncD, to infer potential human lncRNA-disease associations by implementing the random walk with restart method on a lncRNA functional similarity network. The performance of RWRlncD was evaluated by experimentally verified lncRNA-disease associations, based on leave-one-out cross-validation. We achieved an area under the ROC curve of 0.822, demonstrating the excellent performance of RWRlncD. Significantly, the performance of RWRlncD is robust to different parameter selections. Predictively highly-ranked lncRNA-disease associations in case studies of prostate cancer and Alzheimer's disease were manually confirmed by literature mining, providing evidence of the good performance and potential value of the RWRlncD method in predicting lncRNA-disease associations.
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http://dx.doi.org/10.1039/c3mb70608gDOI Listing
August 2014

α-Fetoprotein is a potential survival predictor in hepatocellular carcinoma patients with hepatitis B selected for liver transplantation.

Eur J Gastroenterol Hepatol 2014 May;26(5):544-52

aThe Institute of Organ Transplantation, General Hospital of Chinese People's Armed Police Force, Beijing bFirst Department of Surgery, Shanxi Provincial Corps Hospital of Chinese People's Armed Police Force cDepartment of Health Statistics, Faculty of Preventive Medicine, Fourth Military Medical University, Xi'an, China.

Background: Risk factors can affect candidacy and prognosis following orthotopic liver transplantation (OLT) with antiviral prophylaxis for the treatment of hepatocellular carcinoma (HCC) associated with hepatitis B virus (HBV) and cirrhosis.

Objective: The objective of this study was to investigate the risk factors affecting OLT outcomes in patients with HCC/HBV-induced cirrhosis selected by two contemporary candidacy strategies.

Patients And Methods: From July 2002 to December 2006, 203 patients with HCC/HBV-cirrhosis undergoing OLT with antiviral prophylaxis were evaluated retrospectively. Patients with uncomplicated HCC fulfilling Milan (conservative candidacy group) or Up-to-Seven but not Milan (inclusive candidacy group) criteria were included. Patients received postoperative immunosuppressive therapy. Tumor-free survival and overall survival (OS) were assessed. Univariate analyses between OS and clinical/demographic factors were carried out, including α-fetoprotein (AFP), aspartate aminotransferase, alanine aminotransferase, tumor size, tumor nodule number, vascular invasion, lymph node metastasis, and degree of differentiation. OS was compared between the three groups on the basis of AFP level (≤20, 20-200, and >200 ng/ml).

Results: Conservative candidacy group OS and tumor-free survival were better than the inclusive candidacy group. Low AST, high tumor differentiation, and low AFP were significantly associated with improved OS in the inclusive candidacy group (P<0.05). Low tumor nodule number and AFP levels were significantly associated with improved OS in the conservative candidacy group (P<0.05). AFP of more than 200 ng/ml indicated poorer outcomes in all groups. In multivariate analysis, AFP was an independent predictor of OS.

Conclusion: Up-to-Seven criteria may be more appropriately stratified by AFP, AST, and tumor differentiation, and AFP is a potential independent survival predictor in HBV-associated HCC patients selected for OLT.
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http://dx.doi.org/10.1097/MEG.0000000000000029DOI Listing
May 2014

Characterization of biomass residues and their amendment effects on water sorption and nutrient leaching in sandy soil.

Chemosphere 2014 Jul 12;107:354-359. Epub 2014 Feb 12.

Department of Soil and Water Science, Tropical Research and Education Center, University of Florida, Homestead, FL 33031, USA.

In this study, we evaluated the efficiency of two types of biomass residues (fermentation residues from a bioethanol process, FB; brown mill residues from a papermaking process, BM) as amendments for a sandy soil. The characteristics of these residues including specific surface areas, morphologies and nutrient sorption capacity were measured. The effects of biorefinery residues on water and nutrient retention were investigated in terms of different particle sizes and loadings. The results indicated that bio-based wastes FB and BM were able to significantly improve water and nutrient retention of sandy soil. The residues with larger surface areas had better water and nutrient retention capability. Specifically, in the addition of 10% loading, FB and BM was able to improve water retention by approximately 150% and 300%, while reduce 99% of ammonium and phosphate concentration in the leachate compare to the soil control, respectively.
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http://dx.doi.org/10.1016/j.chemosphere.2013.12.088DOI Listing
July 2014

Isolation and structural characterization of sugarcane bagasse lignin after dilute phosphoric acid plus steam explosion pretreatment and its effect on cellulose hydrolysis.

Bioresour Technol 2014 Feb 23;154:274-81. Epub 2013 Dec 23.

Department of Microbiology & Cell Science, University of Florida, PO Box 110700, Gainesville, FL 32606, USA.

The structure of lignin after dilute phosphoric acid plus steam explosion pretreatment process of sugarcane bagasse in a pilot scale and the effect of the lignin extracted by ethanol on subsequent cellulose hydrolysis were investigated. The lignin structural changes caused by pretreatment were identified using advanced nondestructive techniques such as gel permeation chromatography (GPC), quantitative (13)C, and 2-D nuclear magnetic resonance (NMR). The structural analysis revealed that ethanol extractable lignin preserved basic lignin structure, but had relatively lower amount of β-O-4 linkages, syringyl/guaiacyl units ratio (S/G), p-coumarate/ferulate ratio, and other ending structures. The results also indicated that approximately 8% of mass weight was extracted by pure ethanol. The bagasse after ethanol extraction had an approximate 22% higher glucose yield after enzyme hydrolysis compared to pretreated bagasse without extraction.
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http://dx.doi.org/10.1016/j.biortech.2013.12.072DOI Listing
February 2014