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1.
Springerplus ; 5(1): 2004, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27933260

RESUMO

INTRODUCTION: Beijing subway line 14 includes four stations and approximately 2.8 km of tunnels between the Dongfengbeiqiao and Jingshunlu areas of the city. Due to the surface and underground space limitations of this section, a double-track running tunnel instead of two single-track running tunnels was adopted to connect the two stations. The double-track tunnels were excavated by a 10.22 m diameter earth pressure balance (EPB) shield. It was the first time that an EPB shield more than 10 m in diameter was used in Beijing subway construction. CASE DESCRIPTION: The shield, which passes underneath densely built-up areas of the city and is equipped with a spoke-type cutterhead, with balance between the ground pressure and the earth chamber pressure at the tunnel face, is of great importance. Referring to experiences gained in the EPB shield tunneling, attention was paid to the function of soil conditioning and simultaneous backfilling grouting of the shield, and some special designs were considered in manufacturing the machine. DISCUSSION AND EVALUATION: In addition to the agitating rods welded to the cutterhead, two independently driven agitators were added to fully mix everything in the earth chamber. Independent pipelines were arranged for injecting different conditioning agents. Indoor tests in combination with field tests were conducted to find suitable additives and injection ratios of the additives, and determine the mix ratio of the two-component grout for simultaneous backfilling grouting. A scheme was employed for simultaneously injecting the bentonite slurry at 8% concentration and the foam liquid at 5% concentration to condition the excavated soil. The cement-sodium silicate grout was adopted to fill the tail void and the injection volume per ring was 14.1-15.3 m3. CONCLUSIONS: The performance of the shield and evaluation of the corresponding tunneling technologies are introduced in terms of the shield tunneling induced ground surface settlements. The success of the project is of great significance to Beijing subway construction and underground space utilization. The findings serve as a useful reference for similar projects.

2.
Springerplus ; 5: 527, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27186491

RESUMO

INTRODUCTION: China's largest cities like Beijing and Shanghai have seen a sharp increase in subway network development as a result of the rapid urbanization in the last decade. The cities are still expanding their subway networks now, and many shield tunnels are being or will be constructed in close proximity to the existing operational subway tunnels. The execution plans for the new nearby shield tunnel construction calls for the development of a safety control framework-a set of control standards and best practices to help organizations manage the risks involved. CASE DESCRIPTION: Typical case studies and relevant key technical parameters are presented with a view to presenting the resulting safety control framework. The framework, created through collaboration among the relevant parties, addresses and manages the risks in a systematic way based on actual conditions of each tunnel crossing construction. The framework consists of six parts: (1) inspecting the operational subway tunnels; (2) deciding allowed movements of the existing tunnels and tracks; (3) simulating effects of the shield tunneling on the existing tunnels; (4) doing preparation work; (5) monitoring design and information management; and (6) measures and activation mechanism of the countermeasures. The six components are explained and demonstrated in detail. DISCUSSION AND EVALUATION: In the end, discussions made involve construction and post-construction settlement of the operational tunnel, application of the remedial grouting to rectify excessive settlements of the operational tunnel, and use of the innovative tool of the optical fiber measurement for tunnel movement monitoring. CONCLUSIONS: It is concluded that the construction movement of the tunnel can be controlled within 15 mm when the shield machine is <7 m in excavation diameter. The post-construction settlement of the tunnel buried in the very soft ground is much greater than its construction settlement, and last several years until reaching a final stable state. Two cases are outlined to demonstrate the feasibility of using the remedial grouting to reduce the long-term settlement of the operational tunnels. The more and more segmental tunnels being constructed, there is an increasing need of the optical fiber measurement for tunnel movement monitoring in the near future.

3.
Heart Vessels ; 31(8): 1218-29, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26290166

RESUMO

We decided to assess the prognostic value of NLRP3 inflammasome level in acute coronary syndrome (ACS) patients and whether it was related to coronary atherosclerotic severity. Study population included one-hundred and twenty-three (123) subjects. Peripheral blood monocyte NLRP3 protein level was correlated with clinical presentation, angiographic characteristics and its scoring systems as well as GRACE and TIMI risk scores. Follow-up for major adverse cardiac events (MACE) was carried out at 180 days. Peripheral blood monocyte NLRP3 was found to be elevated in ACS patients (P < 0.05) and showed positive correlation with GRACE score (r = 0.619), TIMI score (r = 0.580), SYNTAX score (r = 0.550), Clinical SYNTAX score (r = 0.564) and Gensini score (r = 0.516). NLRP3 was also increased with increasing number of vessels, the number of lesions present and the presence bifurcation lesions (P < 0.05). Multivariate Cox regression analysis showed NLRP3 to be an independent predictor of MACE (P = 0.043). Kaplan-Meier analysis and receiver operating characteristic curves for NLRP3 showed good predictive value for MACE. There is a positive correlation of NLRP3 level with severity of coronary atherosclerosis. NLRP3 level is a promising prognostic utility and is efficient in event prediction for MACE.


Assuntos
Síndrome Coronariana Aguda/complicações , Síndrome Coronariana Aguda/mortalidade , Doença da Artéria Coronariana/sangue , Creatinina/sangue , Lipídeos/sangue , Proteína 3 que Contém Domínio de Pirina da Família NLR/sangue , Idoso , Estudos de Casos e Controles , Angiografia Coronária , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Prognóstico , Modelos de Riscos Proporcionais , Curva ROC , Medição de Risco , Fatores de Risco , Índice de Gravidade de Doença
4.
ACS Appl Mater Interfaces ; 5(18): 8932-8, 2013 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-23915216

RESUMO

We describe a technique for the fabrication of dense and patterned arrays of aligned silicon oxide nanowires for applications in surface modification, optoelectronic, and electromechanical based devices. Conventional techniques for the fabrication of silicon oxide nanowires based on the vapor-liquid-solid (VLS) chemical vapor deposition (CVD) processes involve the use of high temperatures and catalysts. We demonstrate a technique that extends the use of a plasma thermal reactive ion etching for the fabrication of aligned silicon oxide nanowires with aspect ratios extending up to 20 and lengths exceeding 1 µm. The process incorporates phase separated PS-b-P4VP block copolymer loaded with an iron salt. The iron salt preferentially segregates into the P4VP layer and during an O2 etch is not removed but forms a hexagonally packed array on the silicon oxide substrate. Further etching with CHF3/O2 gas mixture over time can generate nanodots, to nanopillars, and then nanowires of silicon oxide. The photoluminescence property of the as-fabricated nanowire arrays as well as the parasitic ferromagnetic effect from the iron oxide-tipped section of the wires resulting in coalescence under an scanning electron microscope (SEM) are demonstrated. This technique is simpler compared to existing VLS fabrication approaches and can be used for the direct fabrication of patterned arrays of nanowires when a laser interference ablation step is incorporated into the fabrication procedure.

6.
Nanoscale ; 5(9): 3912-7, 2013 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-23532435

RESUMO

We report on the formation of hierarchical nanostructures of Au, PtOx, FexOy and PdOx using a hybrid technique by combining laser interference ablation (LIA) and block copolymer phase separation (BCPS). Different types of hierarchical arrays can be obtained including square, triangular, linear and circular arrays by varying the loading time of the block co-polymer with metallic salts, and the laser interference technique. The primary ordering of the as-generated nanoarrays (30-100 nm) is tunable by changing either the composition of the block copolymer spun from solution or by changing other parameters that affect the phase separation kinetics of the block copolymer, while the secondary ordering of the features can be tuned from 200 nm to 2 µm, by changing the angle of convergence of the laser beams on the patterned substrate. Such a robust method can be applied to the fabrication of other metallic and ceramic materials including Ag, Co, and Ni (O) and has potential use in the large scale fabrication of hierarchical arrays of catalysts that can be used to grow germanium, silicon nanowires using the vapour-liquid-solid growth (VLS) technique. The as-generated arrays can also find use in optical as well as sensor applications for biodetection and biosensing.

7.
Nanotechnology ; 23(21): 215303, 2012 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-22551592

RESUMO

Scalable fabrication of carbon nanotube (CNT) bundles is essential to future advances in several applications. Here, we report on the development of a simple, two-step method for fabricating vertically aligned and periodically distributed CNT bundles and periodically porous CNT films at the sub-micron scale. The method involves laser interference ablation (LIA) of an iron film followed by CNT growth via iron-catalyzed chemical vapor deposition. CNT bundles with square widths ranging from 0.5 to 1.5 µm in width, and 50-200 µm in length, are grown atop the patterned catalyst over areas spanning 8 cm(2). The CNT bundles exhibit a high degree of control over square width, orientation, uniformity, and periodicity. This simple scalable method of producing well-placed and oriented CNT bundles demonstrates a high application potential for wafer-scale integration of CNT structures into various device applications, including IC interconnects, field emitters, sensors, batteries, and optoelectronics, etc.


Assuntos
Cristalização/métodos , Lasers , Membranas Artificiais , Nanotubos de Carbono/química , Nanotubos de Carbono/ultraestrutura , Gases/química , Teste de Materiais , Nanotubos de Carbono/efeitos da radiação , Tamanho da Partícula , Porosidade
8.
Nanotechnology ; 23(1): 015304, 2012 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-22155970

RESUMO

A simple approach for creating periodic nano-cavities and periodic stripes of nano-cavity arrays on poly (3,4-ethylene dioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) thin films using a combination of optical near-field enhancement through self-assembled silica nanospheres and laser interference lithography is presented. Monolayers of close-packed silica nanospheres (800, 600, and 430 nm in diameter) are self-assembled on 2 µm thick PEDOT-PSS electropolymerized films and are subsequently irradiated with 10 ns pulses of 355 nm wavelength laser light. Over areas spanning 2 cm(2), circular nano-cavities with central holes of size 50-200 nm and surrounding craters of size 100-400 nm are formed in the PEDOT-PSS films directly underneath the nanospheres due to strong enhancement (11-18 fold) of the incident light in the near-field, which is confirmed through Mie scattering theory. Predictions from theoretical simulations examining the combined effects of near-field enhancement and interference are in good agreement with the experimental results. The results illustrate the versatility of the described technique for creating nano-cavity arrays or nano-pores in PEDOT-PSS over large areas with designed periodicity and hole size.

9.
ACS Nano ; 5(2): 1476-82, 2011 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-21194200

RESUMO

A method for the large-scale fabrication of patterned organic nanowire (NW) arrays is demonstrated by the use of laser interference patterning (LIP) in conjunction with inductively coupled plasma (ICP) etching. The NW arrays can be fabricated after a short ICP etching of periodic patterns produced through LIP. Arrays of NWs have been fabricated in UV-absorbent polymers, such as PET (polyethylene terephthalate) and Dura film (76% polyethylene and 24% polycarbonate), through laser interference photon ablation and in UV transparent polymers such as PVA (polyvinyl acetate) and PP (polypropylene) through laser interference lithography of a thin layer of photoresist coated atop the polymer surface. The dependence of the structure and morphology of NWs as a function of initial pattern created by LIP and the laser energy dose in LIP is discussed. The absence of residual photoresist atop the NWs in UV-transparent polymers is confirmed through Raman spectroscopy.


Assuntos
Nanotecnologia/métodos , Nanofios/química , Polímeros/química , Lasers , Raios Ultravioleta
10.
Nano Lett ; 10(9): 3414-9, 2010 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-20681617

RESUMO

This article presents an effective approach for patterned growth of vertically aligned ZnO nanowire (NW) arrays with high throughput and low cost at wafer scale without using cleanroom technology. Periodic hole patterns are generated using laser interference lithography on substrates coated with the photoresist SU-8. ZnO NWs are selectively grown through the holes via a low-temperature hydrothermal method without using a catalyst and with a superior control over orientation, location/density, and as-synthesized morphology. The development of textured ZnO seed layers for replacing single crystalline GaN and ZnO substrates extends the large-scale fabrication of vertically aligned ZnO NW arrays on substrates of other materials, such as polymers, Si, and glass. This combined approach demonstrates a novel method of manufacturing large-scale patterned one-dimensional nanostructures on various substrates for applications in energy harvesting, sensing, optoelectronics, and electronic devices.

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