Publications by authors named "Yimin Yao"

27 Publications

  • Page 1 of 1

Lysyl oxidase inhibitors attenuate cyclosporin A-induced nephropathy in mouse.

Sci Rep 2021 Jun 14;11(1):12437. Epub 2021 Jun 14.

Renal Medicine, Kolling Institute, Royal North Shore Hospital, University of Sydney, Sydney, NSW, Australia.

Calcineurin inhibitors, such as Cyclosporin (CsA), are the mainstay of anti-rejection therapy in solid organ transplants but can paradoxically induce progressive nephropathy characterised by renal dysfunction and interstitial fibrosis. Lysyl oxidases (LOXs), a group of enzymes that catalyse extracellular matrix (ECM) crosslinking, were shown to implicate in tissue scarring. It is hypothesized that inhibition of these enzymes may render therapeutic effects against CsA-induced nephropathy. In this study, 6-to-8 weeks old C57BL/6 J mice were administered saline or CsA (30 mg/kg/day s.c) for 16 weeks. At 8 weeks, CsA-treated animals were divided into 5 groups respectively treated with: (1) vehicle, (2) PXS-5505 (Pan-LOX inhibitor), (3) PXS-5382 (LOX-like 2 inhibitor), (4) PXS-5505 for 4 weeks then PXS-5382 for 4 weeks (sequential therapy), and (5) Telmisartan (standard therapy). Our results indicate that CsA administration significantly increased the levels of blood urea nitrogen, glomerular and tubular injury, tubulointerstitial fibrosis, inflammation and oxidative stress in mouse kidney. These changes were associated with upregulated mRNA expression of LOX and LOXL2. Administration of Pan-LOX or LOXL2 inhibitors or the sequential therapy suppressed the expression of ECM proteins (α-SMA, FN and COL1A), matrix metalloproteases (MMP)2 and 9, inflammatory markers (TNFα and MCP-1) and TGF-β1-Smad3 signalling. Among all regimens including telmisartan, only Pan-LOX inhibitor PXS-5505 was able to attenuate uraemia. Collectively, our study suggests that Pan-LOX and LOXL2 inhibition can attenuate progressive nephropathy due to CsA administration.
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http://dx.doi.org/10.1038/s41598-021-91772-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8203624PMC
June 2021

Prevalence of high-risk human papillomavirus and cervical lesion risk factors: A population-based study in Zhejiang, China 2010-2019.

J Med Virol 2021 Aug 3;93(8):5118-5125. Epub 2021 May 3.

Clinical Laboratory, The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China.

This study investigates the epidemiological characteristics of high-risk human papillomavirus (hrHPV) and analyzes the risk of cervical lesions among women in Zhejiang province, China. HPV data were collected retrospectively from a cohort of 67 742 women who underwent routine cervical cancer screening from 2010 to 2019. Precancerous and cervical cancer cases (n = 980) were histologically diagnosed as a low-grade squamous intraepithelial lesion (LSIL; n = 341) or a high-grade squamous intraepithelial lesion (HSIL; n = 499) and invasive cervical cancer (ICC) (n = 140) groups. Disordered logistic regression analysis was used to test the relationship between different degrees of cervical lesions, HPV16/18 infection status, positive rate of p16 (p16), Ki-67 expression, and patient's age in SIL and ICC (270/980 cases) patients. HPV52 (4.7%) was the most prevalent HPV type, followed by HPV16 (3.3%) and HPV58 (2.6%). HPV16 was the most common HPV in SIL, peaking at the age of 30-39. The HPV16 infection rate was significantly higher in HSIL than in LSIL patients; moreover, HPV16, HPV18, and HPV51 infection rates were significantly higher in ICC patients than in HSIL (Bonferroni-adjusted p < 0.0167). The presence of HPV16/18 was also associated with a higher risk of developing HSIL from LSIL (odds ratio [OR] = 9.198, 95% confidence interval [CI]: 2.76-127.49). The increased p16 expression and HPV16/18 were associated with the increased risk of cancer progression (OR = 1.092, 95% CI: 1.03-1.36; OR = 1.495, 95% CI: 1.23-2.19, respectively). The identified hrHPV genotypes in cervical lesions can serve as a baseline indicator for future vaccine assessment in Zhejiang, China.
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http://dx.doi.org/10.1002/jmv.27034DOI Listing
August 2021

mTORC1 signaling pathway regulates macrophages in choroidal neovascularization.

Mol Immunol 2020 05 12;121:72-80. Epub 2020 Mar 12.

Department of Ophthalmology, Second Hospital of Hebei Medical University, Shijiazhuang, 050000, Hebei, China. Electronic address:

Macrophages are involved in choroidal neovascularization (CNV). The mechanistic target of rapamycin complex 1 (mTORC1) is a central cell regulator, but mTORC1 function in macrophages in CNV is not fully understood. We explored the effect of mTORC1 pathway regulation on macrophages in CNV. A laser-induced murine CNV model was performed. Expression of phospho-S6 and F4/80 in CNV lesions was analyzed by immunofluorescence. Macrophages in CNV lesions were found at 1 day after laser treatment, reached a peak at 5 days, and decreased at 7 and 14 days. mTORC1 activity of cells in CNV lesions was increased from 3 to 7 days, and deceased at 14 days. Most infiltrating macrophages in CNV lesions had strong mTORC1 activity at 3 and 5 days that subsequently decreased. In vitro, THP-1 macrophages were polarized to M1 or M2 with rapamycin or siRNA treatment. The human retinal pigment epithelium (RPE) cell line ARPE-19 was co-cultured with macrophages. Cytokine expression of macrophages and ARPE-19 cells was detected by quantitative PCR. Inhibiting mTORC1 activity of macrophages reduced M1 and strengthened M2, which was reversed by mTORC1 hyperactivation. Both M1 and M2 macrophages induced RPE cells to express less PEDF and more MMP9, IL-1β and MCP-1. Inhibiting or enhancing mTORC1 activity of macrophages changed cytokine expression of RPE cells. Together, we demonstrated that macrophage functions in CNV were regulated partly by the mTORC1 pathway, and mTORC1 activity of macrophages influenced the expression of cytokines that are associated with CNV development in RPE cells. This study provides more understanding about the regulatory mechanism of macrophages in CNV.
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http://dx.doi.org/10.1016/j.molimm.2020.03.002DOI Listing
May 2020

A Clinically Relevant Functional Model of Type-2 Cardio-Renal Syndrome with Paraventricular Changes consequent to Chronic Ischaemic Heart Failure.

Sci Rep 2020 01 27;10(1):1261. Epub 2020 Jan 27.

Department of Pharmacology and Toxicology, School of BioMedical Sciences, University of Otago Medical School, Dunedin, New Zealand.

Cardiorenal syndrome, de novo renal pathology arising secondary to cardiac insufficiency, is clinically recognised but poorly characterised. This study establishes and characterises a valid model representative of Type 2 cardiorenal syndrome. Extensive permanent left ventricular infarction, induced by ligation of the left anterior descending coronary artery in Lewis rats, was confirmed by plasma cardiac troponin I, histology and cardiac haemodynamics. Renal function and morphology was assessed 90-days post-ligation when heart failure had developed. The involvement of the paraventricular nucleus was investigated using markers of inflammation, apoptosis, reactive oxygen species and of angiotensin II involvement. An extensive left ventricular infarct was confirmed following coronary artery ligation, resulting in increased left ventricular weight and compromised left ventricular diastolic function and developed pressure. Glomerular filtration was significantly decreased, fractional excretion of sodium and caspase activities were increased and basement membrane thickening, indicating glomerulosclerosis, was evident. Interestingly, angiotensin II receptor I expression and reactive oxygen species levels in the hypothalamic paraventricular nucleus remained significantly increased at 90-days post-coronary artery ligation, suggesting that these hypothalamic changes may represent a novel, valuable pharmacological target. This model provides conclusive morphological, biochemical and functional evidence of renal injury consequent to heart failure, truly representative of Type-2 cardiorenal syndrome.
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http://dx.doi.org/10.1038/s41598-020-58071-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6985167PMC
January 2020

Achieving Significant Thermal Conductivity Enhancement via an Ice-Templated and Sintered BN-SiC Skeleton.

ACS Appl Mater Interfaces 2020 Jan 3;12(2):2892-2902. Epub 2020 Jan 3.

School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States.

Conventional polymer composites normally suffer from undesired thermal conductivity enhancement which has hampered the development of modern electronics as they face a stricter heat dissipating requirement. It is still challenging to achieve satisfactory thermal conductivity enhancement with reasonable mechanical properties. Herein, we present a three-dimensional (3D), lightweight, and mechanically strong boron nitride (BN)-silicon carbide (SiC) skeleton with aligned thermal pathways via the combination of ice-templated assembly and high-temperature sintering. The sintering has introduced atomic-level coupling at the BN-SiC junction which contributes to efficient phonon transport via the newly formed borosilicate glass BCN (0 ≤ ≤ 3) and SiCN (0 ≤ ≤ 4) phases, leading to much lower interfacial thermal resistance. Thus, the obtained BN-SiC skeleton shows satisfactory thermal performance. The prepared 3D BN-SiC/polydimethylsiloxane (PDMS) composites exhibit a maximum through-plane thermal conductivity of 3.87 W·m·K at a filler loading of only 8.35 vol %. The thermal conductivity enhancement efficiency reaches 220% per 1 vol % filler when compared to pure PDMS matrix, superior to other reported BN skeleton-based composites. The feature of our strategy is to allow the oriented three-dimensional skeleton to be strongly bonded by a sintered ceramic phase instead of polymer-like adhesive, namely, to improve the intrinsic thermal conductivity of the skeleton to the greatest extent. This strategy can be applied to develop novel thermal management materials that are lightweight and mechanically tough that rapidly transfer heat. It represents a new avenue to addressing the heat challenges in traditional electronic products.
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http://dx.doi.org/10.1021/acsami.9b19280DOI Listing
January 2020

Highly Compressive Boron Nitride Nanotube Aerogels Reinforced with Reduced Graphene Oxide.

ACS Nano 2019 Jul 18;13(7):7402-7409. Epub 2019 Jun 18.

School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States.

Boron nitride nanotubes (BNNTs), structural analogues of carbon nanotubes, have attracted significant attention due to their superb thermal conductivity, wide bandgap, excellent hydrogen storage capacity, and thermal and chemical stability. Despite considerable progress in the preparation and surface functionalization of BNNTs, it remains a challenge to assemble one-dimensional BNNTs into three-dimensional (3D) architectures (such as aerogels) for practical applications. Here, we report a highly compressive BNNT aerogel reinforced with reduced graphene oxide (rGO) fabricated using a freeze-drying method. The reinforcement effect of rGO and 3D honeycomb-like framework offer the BNNTs/rGO aerogel with a high compression resilience. The BNNTs/rGO aerogels were then infiltrated with polyethylene glycol to prepare a kind of phase change materials. The prepared phase change material composites show zero leakage even at 100 °C and enhanced thermal conductivity, due to the 3D porous structure of the BNNTs/rGO aerogel. This work provides a simple method for the preparation of 3D BNNTs/rGO aerogels for many potential applications, such as high-performance polymer composites.
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http://dx.doi.org/10.1021/acsnano.9b03225DOI Listing
July 2019

Treatment of tuberculous aortic pseudoaneurysm associated with vertebral tuberculosis: A case series and a literature review.

Medicine (Baltimore) 2018 Apr;97(15):e0382

Department of Orthopaedics, West China Hospital, Sichuan University Department of Orthopaedics, PLA 452th Hospital, Chengdu, China.

Rationale: Tuberculous aortic pseudoaneurysm associated with vertebral tuberculosis is a rare disease but with very high mortality. We review the literature and find 19 reports with 22 patients. Here we report three cases with vertebral tuberculosis, who also have tuberculous pseudoaneurysm of the aorta. These patients were treated by different methods. We try to analyze the epidemiology, pathogenesis, presentation, and management of this disease to find the best treatment.

Patient Concerns: The patients presented with different symptoms such as pain (chest, abdominal or back), fever, blood volume reduction or hemorrhagic shock symptoms. Large mass also could be observed by imaging. In addition to clinical manifestations, enhanced computed tomography or magnetic resonance imaging could also help the diagnosis of this disease.

Diagnoses: Tuberculous aortic pseudoaneurysm associated with vertebral tuberculosis.

Interventions: Three patients were treated with anti-tuberculosis(TB) drugs or combined with different sequences surgical treatment: Case 1 refused to receive pseudoaneurysm surgery and only had anti-TB drug treatment; Case 2 received thoracic spinal surgery first; Case 3 received endovascular stent grafting.

Outcomes: Two patients (case 1 and case 2) who refused to undergo aneurysm surgery died. The last patient (case 3) underwent endovascular repair and antibiotic therapy for tuberculosis, and the postoperative course was uneventful; the patient recovered and survived.

Lessons: Once the diagnosis of tuberculous pseudoaneurysm is confirmed, surgical treatment should be provided immediately combined with anti-tuberculosis drugs. The aim of the treatment is to save lives, prevent relapse, and facilitate the return to normal life, regardless of the size of the pseudoaneurysm. The pseudoaneurysm should be treated first to prevent aneurysm rupture before the vertebral tuberculosis surgery.
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http://dx.doi.org/10.1097/MD.0000000000010382DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5908578PMC
April 2018

Vertically Aligned and Interconnected SiC Nanowire Networks Leading to Significantly Enhanced Thermal Conductivity of Polymer Composites.

ACS Appl Mater Interfaces 2018 Mar 9;10(11):9669-9678. Epub 2018 Mar 9.

Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , China.

Efficient heat removal via thermal management materials has become one of the most critical challenges in the development of modern microelectronic devices. However, previously reported polymer composites exhibit limited enhancement of thermal conductivity, even when highly loaded with thermally conductive fillers, because of the lack of efficient heat transfer pathways. Herein, we report vertically aligned and interconnected SiC nanowire (SiCNW) networks as efficient fillers for polymer composites, achieving significantly enhanced thermal conductivity. The SiCNW networks are produced by freeze-casting nanowire aqueous suspensions followed by thermal sintering to consolidate the nanowire junctions, exhibiting a hierarchical architecture in which honeycomb-like SiCNW layers are aligned. The composite obtained by infiltrating SiCNW networks with epoxy resin, at a relatively low SiCNW loading of 2.17 vol %, represents a high through-plane thermal conductivity (1.67 W m K) compared to the pure matrix, which is equivalent to a significant enhancement of 406.6% per 1 vol % loading. The orderly SiCNW network which can act as a macroscopic expressway for phonon transport is believed to be the main contributor for the excellent thermal performance. This strategy provides insights for the design of high-performance composites with potential to be used in advanced thermal management materials.
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http://dx.doi.org/10.1021/acsami.8b00328DOI Listing
March 2018

Construction of 3D Skeleton for Polymer Composites Achieving a High Thermal Conductivity.

Small 2018 03 2;14(13):e1704044. Epub 2018 Feb 2.

Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.

Owing to the growing heat removal issue in modern electronic devices, electrically insulating polymer composites with high thermal conductivity have drawn much attention during the past decade. However, the conventional method to improve through-plane thermal conductivity of these polymer composites usually yields an undesired value (below 3.0 Wm K ). Here, construction of a 3D phonon skeleton is reported composed of stacked boron nitride (BN) platelets reinforced with reduced graphene oxide (rGO) for epoxy composites by the combination of ice-templated and infiltrating methods. At a low filler loading of 13.16 vol%, the resulting 3D BN-rGO/epoxy composites exhibit an ultrahigh through-plane thermal conductivity of 5.05 Wm K as the best thermal-conduction performance reported so far for BN sheet-based composites. Theoretical models qualitatively demonstrate that this enhancement results from the formation of phonon-matching 3D BN-rGO networks, leading to high rates of phonon transport. The strong potential application for thermal management has been demonstrated by the surface temperature variations of the composites with time during heating and cooling.
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http://dx.doi.org/10.1002/smll.201704044DOI Listing
March 2018

Increased arterial stiffness does not respond to renal denervation in an animal model of secondary hypertension.

Annu Int Conf IEEE Eng Med Biol Soc 2017 Jul;2017:258-261

Renal denervation is a novel device based therapy promoted to reduce high blood pressure. We examined the impact of renal denervation on systolic blood pressure, renal function, and arterial stiffness in the Lewis Polycystic Kidney disease (LPK) rodent model of kidney disease. Animals were subjected to bilateral renal denervation or sham surgeries at age 6 and 12 weeks. Systolic blood pressure was monitored by tail-cuff plethysmography and renal function by urinalysis and creatinine clearance. At age 16 weeks, beat-to-beat aortic pulse wave velocity as a functional indicator of arterial stiffness was determined. Renal denervation produced an overall reduction in blood pressure in the LPK [(denervated 164±4 vs. sham-operated 180±6 mmHg, n = 6 per group, P=0.003)] and delayed, but did not prevent, the decline in renal function. Aortic pulse wave velocity was markedly elevated in the LPK compared with Lewis and was not altered by renal denervation in the LPK however a reduction was seen in the control Lewis animals. These results support the hypothesis that renal nerves contribute to secondary hypertension in conditions such as kidney disease.
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http://dx.doi.org/10.1109/EMBC.2017.8036811DOI Listing
July 2017

Learning from Natural Nacre: Constructing Layered Polymer Composites with High Thermal Conductivity.

ACS Appl Mater Interfaces 2017 Sep 13;9(38):33001-33010. Epub 2017 Sep 13.

Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , Shenzhen 518055, China.

Inspired by the microstructures of naturally layered and highly oriented materials, such as natural nacre, we report a thermally conductive polymer composite that consists of epoxy resin and AlO platelets deposited with silver nanoparticles (AgNPs). Owing to their unique two-dimensional structure, AlO platelets are stacked together via a hot-pressing technique, resulting in a brick-and-mortar structure, which is similar to the one of natural nacre. Moreover, the AgNPs deposited on the surfaces of the AlO platelets act as bridges that link the adjacent AlO platelets due to the reduced melting point of the AgNPs. As a result, the polymer composite with 50 wt % filler achieves a maximum thermal conductivity of 6.71 W m K. In addition, the small addition of AgNPs (0.6 wt %) minimally affects the electrical insulation of the composites. Our bioinspired approach will find uses in the design and fabrication of thermally conductive materials for thermal management in modern electronics.
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http://dx.doi.org/10.1021/acsami.7b10115DOI Listing
September 2017

A Combination of Boron Nitride Nanotubes and Cellulose Nanofibers for the Preparation of a Nanocomposite with High Thermal Conductivity.

ACS Nano 2017 05 17;11(5):5167-5178. Epub 2017 Apr 17.

Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , Shenzhen 518055, China.

With the current development of modern electronics toward miniaturization, high-degree integration and multifunctionalization, considerable heat is accumulated, which results in the thermal failure or even explosion of modern electronics. The thermal conductivity of materials has thus attracted much attention in modern electronics. Although polymer composites with enhanced thermal conductivity are expected to address this issue, achieving higher thermal conductivity (above 10 W m K) at filler loadings below 50.0 wt % remains challenging. Here, we report a nanocomposite consisting of boron nitride nanotubes and cellulose nanofibers that exhibits high thermal conductivity (21.39 W m K) at 25.0 wt % boron nitride nanotubes. Such high thermal conductivity is attributed to the high intrinsic thermal conductivity of boron nitride nanotubes and cellulose nanofibers, the one-dimensional structure of boron nitride nanotubes, and the reduced interfacial thermal resistance due to the strong interaction between the boron nitride nanotubes and cellulose nanofibers. Using the as-prepared nanocomposite as a flexible printed circuit board, we demonstrate its potential usefulness in electronic device-cooling applications. This thermally conductive nanocomposite has promising applications in thermal interface materials, printed circuit boards or organic substrates in electronics and could supplement conventional polymer-based materials.
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http://dx.doi.org/10.1021/acsnano.7b02359DOI Listing
May 2017

Polymer Composite with Improved Thermal Conductivity by Constructing a Hierarchically Ordered Three-Dimensional Interconnected Network of BN.

ACS Appl Mater Interfaces 2017 Apr 5;9(15):13544-13553. Epub 2017 Apr 5.

Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , Shenzhen 518055, China.

In this work, we report a fabrication of epoxy resin/ordered three-dimensional boron nitride (3D-BN) network composites through combination of ice-templating self-assembly and infiltration methods. The polymer composites possess much higher thermal conductivity up to 4.42 W m K at relatively low loading 34 vol % than that of random distribution composites (1.81 W m K for epoxy/random 3D-BN composites, 1.16 W m K for epoxy/random BN composites) and exhibit a high glass transition temperature (178.9-229.2 °C) and dimensional stability (22.7 ppm/K). We attribute the increased thermal conductivity to the unique oriented 3D-BN thermally conducive network, in which the much higher thermal conductivity along the in-plane direction of BN microplatelets is most useful. This study paves the way for thermally conductive polymer composites used as thermal interface materials for next-generation electronic packaging and 3D integration circuits.
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http://dx.doi.org/10.1021/acsami.7b02410DOI Listing
April 2017

Ultrafast Self-Healing Nanocomposites via Infrared Laser and Their Application in Flexible Electronics.

ACS Appl Mater Interfaces 2017 Jan 13;9(3):3040-3049. Epub 2017 Jan 13.

School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.

The continuous evolution toward flexible electronics with mechanical robust property and restoring structure simultaneously places high demand on a set of polymeric material substrate. Herein, we describe a composite material composed of a polyurethane based on Diels-Alder chemistry (PU-DA) covalently linked with functionalized graphene nanosheets (FGNS), which shows mechanical robust and infrared (IR) laser self-healing properties at ambient conditions and is therefore suitable for flexible substrate applications. The mechanical strength can be tuned by varying the amount of FGNS and breaking strength can reach as high as 36 MPa with only 0.5 wt % FGNS loading. On rupture, the initial mechanical properties are restored with more than 96% healing efficiency after 1 min irradiation time by 980 nm IR laser. Especially, this is the highest value of healing efficiency reported in the self-healable materials based on DA chemistry systems until now, and the composite exhibits a high volume resistivity up to 5.6 × 10 Ω·cm even the loading of FGNS increased to 1.0 wt %. Moreover, the conductivity of the broken electric circuit which was fabricated by silver paste drop-cast on the healable composite substrate was completely recovered via IR laser irradiating bottom substrate mimicking human skin. These results demonstrate that the FGNS-PU-DA nanocomposite can be used as self-healing flexible substrate for the next generation of intelligent flexible electronics.
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http://dx.doi.org/10.1021/acsami.6b15476DOI Listing
January 2017

Interfacial Engineering of Silicon Carbide Nanowire/Cellulose Microcrystal Paper toward High Thermal Conductivity.

ACS Appl Mater Interfaces 2016 Nov 4;8(45):31248-31255. Epub 2016 Nov 4.

Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , Shenzhen 518055, China.

Polymer composites with high thermal conductivity have attracted much attention, along with the rapid development of electronic devices toward higher speed and better performance. However, high interfacial thermal resistance between fillers and matrix or between fillers and fillers has been one of the primary bottlenecks for the effective thermal conduction in polymer composites. Herein, we report on engineering interfacial structure of silicon carbide nanowire/cellulose microcrystal paper by generating silver nanostructures. We show that silver nanoparticle-deposited silicon carbide nanowires as fillers can effectively enhance the thermal conductivity of the matrix. The in-plane thermal conductivity of the resultant composite paper reaches as high as 34.0 W/m K, which is one order magnitude higher than that of conventional polymer composites. Fitting the measured thermal conductivity with theoretical models qualitatively demonstrates that silver nanoparticles bring the lower interfacial thermal resistances both at silicon carbide nanowire/cellulose microcrystal and silicon carbide nanowire/silicon carbide nanowire interfaces. This interfacial engineering approach provides a powerful tool for sophisticated fabrication of high-performance thermal-management materials.
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http://dx.doi.org/10.1021/acsami.6b10935DOI Listing
November 2016

Renal functional responses in diabetic nephropathy following chronic bilateral renal denervation.

Auton Neurosci 2017 05 3;204:98-104. Epub 2016 Oct 3.

Departments of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand. Electronic address:

Renal innervation operates in conjunction with the intrarenal renin-angiotensin system (RAS) to control tubular reabsorption of sodium and water. This relationship remains unexplored in diabetic nephropathy. This study investigates the effects of acute RAS inhibition and chronic renal denervation on renal function in diabetic rats. Diabetes was induced in mRen-2 rats prior to conducting chronic bilateral denervation in diabetic and normoglycaemic animals. At 12-weeks post-diabetic induction, renal haemodynamics and tubular handling of sodium and water were measured before and after acute captopril infusion. Neither GFR nor renal blood flow were affected by diabetes or chronic renal denervation alone. While captopril produced natriuretic and diuretic responses in chronically-denervated diabetic animals, shown by increases (P<0.05) of 38±14% in absolute (UV), and 71±20% in fractional sodium excretion (FE), and 68±17% in urine volume (UV); in the innervated-diabetic group captopril produced anti-natriuretic effects (UV and FE reduced by 41±10% and 29±13%, respectively; all P<0.05). This difference was not observed however in normoglycaemic groups where RAS inhibition produced anti-natriuretic (normoglycaemic denervated vs. innervated: 56±14% vs. 49±14% UV; 45±13% vs. 37±14% FE) and anti-diuretic (normoglycaemic-denervated vs. innervated: 34±8% vs. 38±10% UV) effects in both denervated and innervated animals. These data indicate that renal neuronal control is altered in chronic hyperglycaemia. The role of the RAS in sodium conservation in the diabetic kidney, appears to be more significant in the absence of renal innervation, suggesting that the interaction between the RAS and renal sympathetic nervous system is responsible for changes in renal function in diabetic nephropathy.
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http://dx.doi.org/10.1016/j.autneu.2016.09.019DOI Listing
May 2017

Highly Thermally Conductive Composite Papers Prepared Based on the Thought of Bioinspired Engineering.

ACS Appl Mater Interfaces 2016 Jun 13;8(24):15645-53. Epub 2016 Jun 13.

Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , Shenzhen 518055, China.

The rapid development of modern electronics and three-dimensional integration sets stringent requirements for efficient heat removal of thermal-management materials to ensure the long lifetime of the electronics. However, conventional polymer composites that have been used widely as thermal-management materials suffer from undesired thermal conductivity lower than 10 W m(-1) K(-1). In this work, we report a novel thermally conductive composite paper based on the thought of bioinspired engineering. The advantage of the bioinspired papers over conventional composites lies in that they possess a very high in-plane thermal conductivity up to 21.7 W m(-1) K(-1) along with good mechanical properties and high electrical insulation. We attribute the high thermal conductivity to the improved interfacial interaction between assembled components through the introduction of silver nanoparticles and the oriented structure based on boron nitride nanosheets and silicon carbide nanowires. This thought based on bioinspired engineering provides a creative opportunity for design and fabrication of novel thermally conductive materials, and this kind of composite paper has potential applications in powerful integrated microelectronics.
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http://dx.doi.org/10.1021/acsami.6b04636DOI Listing
June 2016

Silver Nanoparticle-Deposited Boron Nitride Nanosheets as Fillers for Polymeric Composites with High Thermal Conductivity.

Sci Rep 2016 Jan 19;6:19394. Epub 2016 Jan 19.

Department of Electronics Engineering, The Chinese University of Hong Kong, Hong Kong, China.

Polymer composites with high thermal conductivity have recently attracted much attention, along with the rapid development of the electronic devices toward higher speed and performance. However, a common method to enhance polymer thermal conductivity through an addition of high thermally conductive fillers usually cannot provide an expected value, especially for composites requiring electrical insulation. Here, we show that polymeric composites with silver nanoparticle-deposited boron nitride nanosheets as fillers could effectively enhance the thermal conductivity of polymer, thanks to the bridging connections of silver nanoparticles among boron nitride nanosheets. The thermal conductivity of the composite is significantly increased from 1.63 W/m-K for the composite filled with the silver nanoparticle-deposited boron nitride nanosheets to 3.06 W/m-K at the boron nitride nanosheets loading of 25.1 vol %. In addition, the electrically insulating properties of the composite are well preserved. Fitting the measured thermal conductivity of epoxy composite with one physical model indicates that the composite with silver nanoparticle-deposited boron nitride nanosheets outperforms the one with boron nitride nanosheets, owning to the lower thermal contact resistance among boron nitride nanosheets' interfaces. The finding sheds new light on enhancement of thermal conductivity of the polymeric composites which concurrently require the electrical insulation.
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http://dx.doi.org/10.1038/srep19394DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4726004PMC
January 2016

Ice-Templated Assembly Strategy to Construct 3D Boron Nitride Nanosheet Networks in Polymer Composites for Thermal Conductivity Improvement.

Small 2015 Dec 19;11(46):6205-13. Epub 2015 Oct 19.

Department of Electronics Engineering, The Chinese University of Hong Kong, Hong Kong, 999077, China.

Owing to the growing heat removal issue of modern electronic devices, polymer composites with high thermal conductivity have drawn much attention in the past few years. However, a traditional method to enhance the thermal conductivity of the polymers by addition of inorganic fillers usually creates composite with not only limited thermal conductivity but also other detrimental effects due to large amount of fillers required. Here, novel polymer composites are reported by first constructing 3D boron nitride nanosheets (3D-BNNS) network using ice-templated approach and then infiltrating them with epoxy matrix. The obtained polymer composites exhibit a high thermal conductivity (2.85 W m(-1) K(-1)), a low thermal expansion coefficient (24-32 ppm K(-1)), and an increased glass transition temperature (T(g)) at relatively low BNNSs loading (9.29 vol%). These results demonstrate that this approach opens a new avenue for design and preparation of polymer composites with high thermal conductivity. The polymer composites are potentially useful in advanced electronic packaging techniques, namely, thermal interface materials, underfill materials, molding compounds, and organic substrates.
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http://dx.doi.org/10.1002/smll.201502173DOI Listing
December 2015

Chronic bilateral renal denervation reduces cardiac hypertrophic remodelling but not β-adrenergic responsiveness in hypertensive type 1 diabetic rats.

Exp Physiol 2015 Jun;100(6):628-39

Department of Physiology - HeartOtago, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.

New Findings: What is the central question of this study? Can bilateral renal denervation, an effective antihypertensive treatment in clinical and experimental studies, improve cardiac β-adrenoceptor responsiveness in a diabetic model with underlying hypertension? What is the main finding and its importance? Bilateral renal denervation did not affect β-adrenergic responsiveness in the diabetic hypertensive rat heart, but denervation reduced the hypertension-induced concentric hypertrophic remodelling. This suggests that the positive haemodynamic changes induced by renal denervation are most likely to reflect an attenuation of sympathetic effects on the systemic vasculature and/or the renal function rather than direct sympathetic modulation of the heart. Bilateral renal denervation (BRD) has been shown to normalise blood pressure in clinical and experimental studies of hypertension by reducing systemic sympathetic output. This study determined the effect of BRD on cardiac β-adrenoceptor (AR) responsiveness in a diabetic model with underlying hypertension using the transgenic (mRen-2)27 rats. Bilateral renal denervation or sham surgeries were conducted repeatedly at 3, 6 and 9 weeks in Ren-2 rats with or without streptozotocin (STZ)-induced diabetes (4 × n = 7); Sprague-Dawley rats (n = 6) served as control animals. Cardiac function was determined in isolated hearts at 18 weeks of age. Normalised left ventricular developed pressure and relaxation was recorded in response to incremental concentrations of the β-AR agonist isoprenaline (from 10-10 to 10-7 m) or the β3 -AR agonist BRL37344 (from 10(-13) to 10(-6 ) m). Expression levels of β1 -AR were determined by Western blot. Both inotropic and lusitropic β-AR responsiveness was reduced in the hypertensive diabetic hearts, but these responses were unaltered after BRD. Expression levels of β1 -AR were increased after BRD (Sham, 0.85 ± 0.11 versus 1.01 ± 0.05 a.u.; BRD, 1.45 ± 0.11 versus 1.46 ± 0.07 a.u.; Ren-2 versus Ren-2 STZ, P < 0.05 versus Sham). No effect of β3 -AR agonist stimulation with BRL37344 was observed. Interestingly, BRD increased left ventricular diastolic volume in both the Ren-2 and the Ren-2 STZ groups. Bilateral renal denervation did not restore the attenuated cardiac β-AR responsiveness in the diabetic hypertensive rats, but it reduced the extent of hypertension-induced concentric hypertrophic remodelling. Thus, the haemodynamic protection offered by renal denervation appears to reflect an attenuated sympathetic innervation of the systemic vasculature and/or kidney rather than a direct cardiac effect.
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http://dx.doi.org/10.1113/EP085021DOI Listing
June 2015

The effect of losartan on differential reflex control of sympathetic nerve activity in chronic kidney disease.

J Hypertens 2015 Jun;33(6):1249-60

aAustralian School of Advanced Medicine, Macquarie University bHeart Research Institute and University of Sydney, Newtown, Sydney, New South Wales, Australia.

Background: The effect of angiotensin II type I receptor (AT1R) inhibition on the pattern of reflex sympathetic nerve activity (SNA) to multiple target organs in the Lewis polycystic kidney (LPK) rat model of chronic kidney disease was determined.

Methods: Mean arterial pressure (MAP), splanchnic SNA (sSNA), renal SNA (rSNA) and lumbar SNA (lSNA) were recorded in urethane-anaesthetized LPK and Lewis controls (total n = 39). Baroreflex, peripheral and central chemoreflex, and somatosensory reflex control of SNA (evoked by phenylephrine/sodium nitroprusside infusion, 10% O2 in N2 or 100% N2 ventilation, 5% CO2 ventilation and sciatic nerve stimulation, respectively) were determined before and after administration of losartan (AT1R antagonist 3 mg/kg, intravenous).

Results: Baseline MAP was higher in LPK rats and baroreflex control of sSNA and rSNA, but not lSNA, was reduced. Losartan reduced MAP in both strains and selectively improved baroreflex gain for sSNA (-1.2 ± 0.1 vs. -0.7 ± 0.07 %/mmHg; P < 0.05) in LPK. The peripheral and central chemoreflex increased MAP and all SNA in Lewis controls, but reduced or had no effect on these parameters, respectively, in LPK. The SNA response to somatosensory stimulation was biphasic, with latency to second peak less in LPK. Losartan ameliorated the depressor and sympathoinhibitory responses to peripheral chemoreflex stimulation in the LPK, but did not alter the central chemoreflex or somatosympathetic responses.

Conclusion: Inhibition of the AT1R selectively improved baroreflex control of sSNA and peripheral chemoreflex control of all three sympathetic nerve outflows in the LPK rat, suggesting these anomalies in reflex function are driven in part by angiotensin II.
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http://dx.doi.org/10.1097/HJH.0000000000000535DOI Listing
June 2015

Chronic bilateral renal denervation attenuates renal injury in a transgenic rat model of diabetic nephropathy.

Am J Physiol Renal Physiol 2014 Aug 4;307(3):F251-62. Epub 2014 Jun 4.

Department of Pharmacology, University of Otago, Dunedin, New Zealand;

Bilateral renal denervation (BRD) has been shown to reduce hypertension and improve renal function in both human and experimental studies. We hypothesized that chronic intervention with BRD may also attenuate renal injury and fibrosis in diabetic nephropathy. This hypothesis was examined in a female streptozotocin-induced diabetic (mRen-2)27 rat (TGR) shown to capture the cardinal features of human diabetic nephropathy. Following diabetic induction, BRD/sham surgeries were conducted repeatedly (at the week 3, 6, and 9 following induction) in both diabetic and normoglycemic animals. Renal denervation resulted in a progressive decrease in systolic blood pressure from first denervation to termination (at 12 wk post-diabetic induction) in both normoglycemic and diabetic rats. Renal norepinephrine content was significantly raised following diabetic induction and ablated in denervated normoglycemic and diabetic groups. A significant increase in glomerular basement membrane thickening and mesangial expansion was seen in the diabetic kidneys; this morphological appearance was markedly reduced by BRD. Immunohistochemistry and protein densitometric analysis of diabetic innervated kidneys confirmed the presence of significantly increased levels of collagens I and IV, α-smooth muscle actin, the ANG II type 1 receptor, and transforming growth factor-β. Renal denervation significantly reduced protein expression of these fibrotic markers. Furthermore, BRD attenuated albuminuria and prevented the loss of glomerular podocin expression in these diabetic animals. In conclusion, BRD decreases systolic blood pressure and reduces the development of renal fibrosis, glomerulosclerosis, and albuminuria in this model of diabetic nephropathy. The evidence presented strongly suggests that renal denervation may serve as a therapeutic intervention to attenuate the progression of renal injury in diabetic nephropathy.
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http://dx.doi.org/10.1152/ajprenal.00578.2013DOI Listing
August 2014

Anatomical study of anterior column screw tunnels through virtual three-dimensional models of the pelvis.

Eur J Orthop Surg Traumatol 2015 Jan 11;25(1):105-10. Epub 2014 Jan 11.

Department of Orthopaedics Surgery, PLA General Hospital, Fuxinglu 28, Haidian District, Beijing, 100853, China.

We created 66 male and 74 female virtual three-dimensional models of the pelvis based on computed tomography data from 140 patients. Virtual cylindrical bolts (VCBs) were placed in the anterior column (AC), which was then resliced serially along the bolt's long axis. AC screw tunnel mainly comprises two long, narrow triangular prisms [zone III (acetabular fossa) and zone V (obturator foramen)]--forming the III/V angle--linked by a larger, shorter cylinder [zone IV (acetabular notch)]. VCBs' mean length and maximum diameter were 111.13 ± 7.33 and 7.37 ± 1.90 mm, respectively. The models' anatomical zone lengths were similar between the sexes. Zone V's narrowest diameters and the III/V angles were significantly different. VCBs >6.5 mm were accommodated in 65 of 66 male models and 31 of 74 female models. VCBs >5.0 and <6.5 mm were accommodated in one male and 30 female models. Eleven female models accommodated only VCBs >3.5 and <5.0 mm. However, to 13 female pelvic models with maximum VCB accommodation of <5 mm for the anterior column, the maximum diameter of the VCBs was 8.23 ± 1.22 mm in medial passage and 10.3 ± 1.91 mm in lateral passage, respectively. Percutaneous fixation of the AC with screws is a safe technique, even though in Chinese female patients. The narrowest diameters in zone V and the III/V angles are the key factors for application of AC screws. Female patients with a smaller interosseous space at zone V and a large III/V angle can accommodate segmental passage screws.
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http://dx.doi.org/10.1007/s00590-013-1410-zDOI Listing
January 2015

Histomorphological researches on large porous hydroxyapatite cylinder tubes with polylactic acid surface coating in different nonskeletal sites in vivo.

J Biomed Mater Res A 2012 May 18;100(5):1203-8. Epub 2012 Feb 18.

Department of Orthopedics, 452nd Hospital of Chinese PLA, Chengdu, Sichuan, People's Republic of China.

Porous hydroxyapatite (HA) ceramic cylinder tubes coated with polylactic acid on the exposed surfaces were implanted in four nonskeletal sites (omentum, peritoneum, vastus lateralis, and side of femur). Six months postoperatively, proper amount of Chinese ink was injected to dye the implanting areas. Decalcified and nondecalcified sections were observed under inverted microscope. The results showed that the soft tissues around the HA cylinder tubes in peritoneum, vastus lateralis, and side of femur groups appeared visible black. Some small blacked vascular architectures were also discernible. However in omentum group, only small number of blacked vessels existed. Histological observations indicated that vascularization and ossification occurred in peritoneum, vastus lateralis, and side of femur groups. In omentum group, there was no any sign of vascularization and ossification. A conclusion could be made in this study that excepting bones and muscles, parietal peritoneum could serve as a potential spot for culturing histoengineering hydroxyapatite (HA)-polylactic acid (PLA) ceramic bone substitutes.
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http://dx.doi.org/10.1002/jbm.a.34067DOI Listing
May 2012

A system for neural recording and closed-loop intracortical microstimulation in awake rodents.

IEEE Trans Biomed Eng 2009 Jan;56(1):15-22

Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720, USA.

There is growing interest in intracortical microstimulation as a means of providing sensory input in neuroprosthetic systems. We believe that precisely controlling the timing and parameters of stimulation in closed loop can significantly improve the efficacy of this technique. Here, we present a system for closed-loop microstimulation in awake rodents chronically implanted with multielectrode arrays. The system interfaces with existing commercial recording and stimulating hardware. Using custom-made hardware, we can stimulate and record from electrodes on the same implanted array and significantly reduce the stimulation artifact. Stimulation sequences can either be preprogrammed or triggered by neural or behavioral events. Specifically, this system can provide feedback stimulation in response to action potentials or features in the local field potential recorded on any of the electrodes within 15 ms. It can also trigger stimulation based on behavioral events, such as real-time tracking of rat whiskers captured with high-speed video. We believe that this system, which can be recreated easily, will help to significantly refine the technique of intracortical microstimulation and advance the field of neuroprostheses.
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http://dx.doi.org/10.1109/TBME.2008.2005944DOI Listing
January 2009

Comparison of stress distribution of thoracolumbar vertebrae under forces with CT value.

Chin J Traumatol 2000 Nov;3(4):219-222

The Air Force Hospital of Chengdu, Sichuan 610061, China.

OBJECTIVE: To provide a new method to estimate t he effectiveness of thoracolumbar vertebral finite element model. METHODS: A mechanical model of human thoracolumbar vertebrae mo tion segment was made using three-dimensional finite element method and the str ess distribution of vertically compressed thoracolumbar vertebrae was analyzed, meanwhile, 20 patients with burst fracture of thoracolumbar vertebrae were t ested by CT to calculated average CT value at ascertained different points of th oracolumbar vertebrae. The calculated results and effective stress at the same p osition were analyzed with straight line correlation. RESULTS: The stress level of different position of thoracolumba r vertebrae under vertical compressive force was positively correlated with the correlative CT value, and the regressive style, Y=214.028+45.268X, r=0.7386, P<0.05 (n=8) showed a statistical significance. CONCLUSIONS: To study mechanism of thoracolumbar vertebrae in juries under different forces has clinical significance.
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November 2000

Experimental study on early division of cross-finger pedicle flap and its clinical application.

Chin J Traumatol 2000 Aug;3(3):159-162

Department of Reparative and Reconstructive Surgery, Hospital of Air Force, Chengdu 610021, China.

OBJECTIVE: To observe the revascularization and the opportunity of cross-finger flap. METHODS: An animal model was developed to permit daily monit oring of neovascularization of the flap with autoradiography, tissue transparent technique, gross observation and histological examination. RESULTS: The revascularization of the flap was chiefly raised f rom the surrounding tissues. The pedicles of 334 cross-finger flaps of the pati ents were successfully divided from 1 to 5 d after operations, averagely 3. 3 d. All of the cases showed satisfatory results according to a follow-up sur vey of 3 to 72 mon. The results further proved that the revascularization of the cross-finger flaps had accomplished within 3 d. CONCLUSIONS: It suggests that the division of a cross-finger f lap can be carried out between the 3rd and 5th day after operation with a high d egree of safety.
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August 2000
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