基于超声法检测钢管混凝土质量

综述了超声法检测钢管混凝土拱桥质量缺陷的理论和方法,重点研究超声波通过钢管混凝土试件常规缺陷状况下的参数特征和波形特征。实现了钢管混凝土常规缺陷的定性测量,为超声法检测钢管混凝土拱桥提拱了有益的参考,对于实际工程的检测有很大的实用价值。

氧化石墨烯的制备与表征

氧化石墨烯(GO)是通过氧化石墨而得到的其衍生物[1-3],在其表面含有一些丰富的含氧官能团[4-6].GO因具有层状的二维结构以及π共轭体系,因而可以通过非共价键作用与各种有机、生物分子连接在一起.在溶剂中,氧化石墨烯和分子经过一个复杂的离子和非离子之间相互作用[7-9].GO被人们看成是一个弱酸型的阳离子交换树脂,其存在可电离的-COOH,可以与金属阳离子或者是带正电荷的有机分子发生离子交换[10].以化学药物修饰的GO,使其对生物体内特定细胞的杀死以及抗癌活性等方面具有良好的效果[11-12].这使得以GO为载体的纳米超分子在提高治疗效率和临床方面有着更显著的作用[13-14].在本文中,我们通过Hummers法[15]和超生辅助Hummers法[16]分别制备了GO,并分别利用红外光谱对其进行表征,结果表明超生辅助Hummers法制备的GO纯度相对较高些.

Importance of Percutaneous Radiofrequency Ablation for Recurrent Hepatocellular Carcinoma

Objective: To study the importance of percutaneous radiofrequency ablation (PRFA) guided by ultrasound for inoperable recurrent hepatocellular carcinoma.Methods: Forty-seven patients with inoperable recurrent hepatocellular carcinoma underwent percutaneous radiofrequency ablation (PRFA) under ultrasond between October 1999 and July 2001. Twenty-four patients had single recurrent tumor and 23 patients had multiple lesions. Twelve patients had single lesion with less than 3.5 cm in diameter. All patients were followed up to examine the value of AFP, MRI or CT after PRFA. Kaplan-Meier estimation was used to analyze the survival rate.Results: The 1-, 2- and 3-year survival rate in single lesion group was 65.2%, 37.5% and 37.5% respectively. The survival rate of 1 and 2 years was 41.7% and 19.5% in the multiple lesions group. The 1-, 2-and 3-year survival rate in single lesion groups with less than 3.5 cm in diameter was 83.3%, 51.4% and 51.4% respectively.Conclusion: PRFA is one of the important comprehensive methods for recurrent hepatocellular carcinoma. According to the size, number and recurrent time, PRFA can be performed separately or combined with transcatheter arterial chemoembolization for inoperable recurrent hepatocellular carcinoma. This method can control the recurrence and increase the survival rate effectively. Key words recurrence - hepatocellular cacinoma - radiofrequency ablation

Hemodynamics in the portal vein evaluated by pulse wave Doppler ultrasonography in patients with chronic hepatitis C treated with interferon

AIM: To employ pulse wave Doppler ultrasonography to evaluate the changes in portal blood flow velocity in patients with chronic hepatitis C (CHC) receiving interferon (IFN) treatment. METHODS: The subjects in this study were 14 patients (13 men and l woman) with CHC who received IFN treatment. Portal blood flow velocity was measured in the vessels at the porta hepatis at four time points: before IFN administration (pre-IFN), 2 wk after the start of administration (wk 2), 24 wk after the start of administration (wk 24, i.e., the end of IFN administration), and 24 wk after the end of administration (wk 48). RESULTS: The patients with CHC in whom IFN treatment resulted in complete elimination or effective elimination of viruses showed a significant increase in portal blood flow velocity at the end of IFN treatment compared with that before IFN treatment. In contrast, when IFN was ineffective, no significant increase in portal blood flow velocity was observed at wk 24 or 48 compared with the pre-IFN value. In addition, the patients with CHC in whom IFN was ineffective showed significantly lower portal blood flow velocity values than control subjects at all measurement time points. CONCLUSION: Pulse wave Doppler ultrasonography is a noninvasive and easily performed method for evaluating the effects of IFN treatment in patients with CHC. This technique is useful for measuring portal blood flow velocity before and 24 wk after IFN administration in order to evaluate the changes over time, thus assessing the effectiveness of IFN treatment.

Fabrication of cobalt aluminum-layered double hydroxide nanosheets/carbon spheres composite as novel electrode material for supercapacitors

A new design route was presented to fabricate cobalt aluminum-layered double hydroxide(CoAl-LDH)thin layers whichgrow on carbon spheres(CSs)through a growth method.The CoAl-LDH thin layers consist of nanoflakes with a thickness of20nm.The galvanostatic charge-discharge test of the CoAl-LDH/CSs composite shows a great specific capacitance of1198F/g at1A/g(based on the mass of the CoAl-LDH/CSs composite)in6mol/L KOH solution,and the composite displays an impressive specificcapacitance of920F/g even at a high current density of10A/g.Moreover,the composite remains a specific capacitance of928F/gafter1000cycles at2A/g,and the specific capacitance retention is84%,indicating that the composite has high specific capacitance,excellent rate capability and good cycling stability in comparison to pristine CoAl-LDH.

Membrane Engineering for Green Process Engineering

Green process engineering, which is based on the principles of the process intensification strategy, can provide an important contribution toward achieving industrial sustainable development. Green process engineering refers to innovative equipment and process methods that are expected to bring about substan- tial improvements in chemical and any other manufacturing and processing aspects. It includes decreasing production costs, equipment size, energy consumption, and waste generation, and improving remote con- trol, information fluxes, and process flexibility. Membrane-based technology assists in the pursuit of these principles, and the potential of membrane operations has been widely recognized in the last few years. This work starts by presenting an overview of the membrane operations that are utilized in water treatment and in the production of energy and raw materials. Next, it describes the potential advantages of innovative membrane-based integrated systems. A case study on an integrated membrane system （IMS） for seawa- ter desalination coupled with raw materials production is presented. The aim of this work is to show how membrane systems can contribute to the realization of the goals of zero liquid discharge （ZLD）, total raw materials utilization, and low energy consumption.

Life detection and location methods using UWB impulse radar in a coal mine

An ultra-wideband impulse radar was studied for the detection of buried life in coal mines. An improved Empirical Mode Decomposition (EMD) method based on a cross-correlation filter was proposed for reduction of multipath and noise interference. Multipath interference was first removed by cross-corre- lation filtering. Then the delays of each pulse in every echo were summed. An EMD algorithm was used for noise reduction for the total delay of each echo. The corresponding EMD results of every echo were then summed and averaged. Finally, evidence for the existence of buried life and their position were obtained from amplitude-frequency curves of the averaged EMD results. Detailed simulation experi- ments are presented to validate the effectiveness of this proposed method. The experimental results show that this method can efficiently eliminate multipath interference and reduce noise interference in echoes, which makes detection and location of buried life in coal mines more accurate.

超声提取当归苦参丸方药条件的优选

采用正交设计优选其工艺条件．用高效液相色谱法测定阿魏酸含量，用酸碱滴定法测定苦参总碱的含量。为当归苦参丸剂型改革研究优选提取工艺。确定工艺条件为：10倍量水在10℃下超声提取30min。当归苦参丸优选工艺可行。

A Screening Program for Overweight Status Among Schoolgirls in Saudi Arabia： A Proposed Co-design Project to Tackle the Problem

The paper realizes the importance of communicating with schools to conduct nutritional screening, assessment and intervention programs for obesity and related risk factors to tackle the problem at earlier stage. The screening program was conducted by dietetics＇ students ＂under supervision＂ as part of their practice and community services to apply some assessment method for mritional status. Two intermediate schools for girls in Jeddah city were involved in the screening stage, followed by a full nutritional assessment and implementation of a designed intervention program at one of the schools. At screening stage, interview questionnaires for diet histories and anthropometric measurements used to screen overweight status and related food patterns. National and international references data used for assessment and comparison. Following screening approach, a designed comprehensive nutritional assessment and intervention program was piloted at one of the screened schools for overweight status. For screening stage： the overall prevalence of overweight girls is 61% （n = 81 out of 133） of the population, 73% （n = 91） of girls were centrally obese. Almost 3/4 of all students reported no participations in any type of physical activities/exercises. Dietary behaviors included non-consumption of breakfast （83%） and low intake of fruit and vegetables （38%）. For intervention stage, the present report concentrates on data concerning post intervention changes in Body Mass Index （BMI） and Waist Circumference （WC）. By the 30 days of intervention there were significant changes in values for BMI according to Saudi growth chart （p value = 0.009） with no changes among the control group. No statistically significant difference in the mean WC of the group. Study＇s results suggest that approaching young girls through schools to screen, assess and intervene overweight status and risk factors is vital. Although the non-random selection of only two schools for screening the prevalence of overweight status among school girls prevent the geralizability of the study findings to wider population, previous studies used random selection of schools and large sample sizes showed a high prevalence of overweight status among Saudi students Therefore, designing and piloting of an intervention program for implementation at a national level is useful to tackle theproblem.

Simulating Ultrasound Reflections Using Rayleigh Integral Method in Complex Biological Media

This paper exploits the Rayleigh integral method to simulate the propagation of transmitted ultrasonic waves and received echoes through various media. Performed simulations study the effect of apodization using different types of windows and the effect of medium properties on the reflections obtained. All estimations are done using the Rayleigh integral method simplified by the Fresnel approximation. Five different interfaces are considered： tissue-bone-tissue, tissue-fat-bone, fat-muscle-bone, air-fat-bone and water-fat-bone. The apodization simulations show that the hamming window is more efficient than the rectangular and triangular windows for obtaining a more consistent beam. In the second set of simulations, reflections are mapped with respect to the depth from which these reflections are generated. It demonstrates that the solid and water media allow for the attainment of echoes from deeper regions as compared to the air medium. Matlab is used as the simulation framework.

A direct atomic layer deposition method for growth of ultra-thin lubricant tungsten disulfide films

We describe a direct atomic layer deposition method to grow lubricant tungsten disulfide （WS2） films. The WS2 films were deposited on a Si （100） substrate and a zinc sulfide （ZnS） film coated the Si （100） substrate using tungsten hexacarbonyl and hydrogen sulfide as precursors. The ZnS film served as an intermediate layer to facilitate the nucleation and growth of the WS2 films. The thickness of the WS2 films was measured via scanning electron microscope, the microstructure was probed with an X-ray diffractometer and a transmission electron microscope. The friction coefficient was measured with a ball-on-disk tester under dry nitrogen. The results reveal that the WS2 films deposited on both substrates are N175 nm and have （002） and （101） crystal orientations. The WS2 film deposited on the ZnS coated Si substrate exhibits a stronger （002） orientation and a denser crystal structure than that deposited on the Si substrate. The WS2 films on both substrates have low friction coefficients. How- ever, due to the stronger （002） orientation and denser crystal structure, the friction coefficient of the WS2 film deposited on ZnS coated Si substrate is smaller with longer wear life.

Grain oriented growth and properties of ultra-high temperature CaBi_2Nb_2O_9 piezoelectric ceramics

CaBi2Nb2O9 (CBNO) ceramics was prepared at 1050℃ using regular flake-like CBNO powders as the precursor, and synthe-sized by the molten salts synthesis method. The tropism degree and microstructure of the ceramics were analyzed, and the die-lectric, ferroelectric and piezoelectric properties were characterized. Compared with conventional methods, the properties of CBNO ceramics by the new preparation method were found to be better. As the sinter temperature decreases, the grain growth becomes regular with textured features. The polarization process becomes easy to be realized at room temperature. Moreover, the dielectric loss decreases and the piezoelectric constant increases significantly.