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Search Results: 1 - 10 of 28374 matches for " Hongfei Zhu "
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Phononic Thin Plates with Embedded Acoustic Black Holes
Hongfei Zhu,Fabio Semperlotti
Physics , 2014, DOI: 10.1103/PhysRevB.91.104304
Abstract: We introduce a class of two-dimensional non-resonant single-phase phononic materials and investigate its peculiar dispersion characteristics. The material consists of a thin plate-like structure with an embedded periodic lattice of Acoustic Black Holes. The use of these periodic tapers allows achieving remarkable dispersion properties such as Zero Group Velocity in the fundamental modes, negative group refraction index, bi-refraction, and mode anisotropy. The dispersion properties are numerically investigated using a three-dimensional supercell plane wave expansion method. The effect on the dispersion characteristics of key geometric parameters of the black hole, such as the taper profile and the residual thickness, are also explored.
Achieving Selective Damage Interrogation and Sub-Wavelength Resolution in Thin Plates with Embedded Metamaterial Acoustic Lenses
Fabio Semperlotti,Hongfei Zhu
Physics , 2013, DOI: 10.1063/1.4892017
Abstract: In this study, we present an approach to ultrasonic beamforming and high resolution identification of acoustic sources having critical implications for structural health monitoring technology. The proposed concept is based on the design of dynamically tailored structural elements via embedded acoustic metamaterial lenses. This approach provides a completely new alternative to conventional phased-array technology enabling the formation of steerable and collimated (or focused) ultrasonic beams by exploiting a single transducer. The ultrasonic beams can be steered by simply tuning the frequency of the excitation. Also, the embedded lens can be designed to achieve sub-wavelength resolution to incipient clustered damage.
A passively tunable non-resonant acoustic metamaterial lens for selective ultrasonic excitation
Hongfei Zhu,Fabio Semperlotti
Physics , 2014, DOI: 10.1063/1.4894279
Abstract: In this paper, we present an approach to ultrasonic beam-forming and beam-steering in structures based on the concept of embedded non-resonant acoustic metamaterial lenses. The lens design exploits the principle of acoustic drop-channel which enables the dynamic coupling of multiple ultrasonic waveguides at selected frequencies. In contrast with currently available technology, the embedded lens allows generating directional excitation by means of a single ultrasonic transducer. The lens design and performance are numerically investigated by using Plane Wave Expansion and Finite Difference Time Domain techniques applied to bulk structures. Then, the design is experimentally validated on a thin aluminum plate where the lens is implemented by through-holes. The dynamic response of the embedded lens is estimated by reconstructing, via Laser Vibrometry, the velocity field induced by a piezoelectric shaker source.
Synthetic Resveratrol Derivatives and Their Biological Activities: A Review  [PDF]
Ya Liu, Yi Liu, Hongfei Chen, Xu Yao, Yan Xiao, Xianliang Zeng, Qutong Zheng, Yun Wei, Chen Song, Yinxiang Zhang, Peng Zhu, Juan Wang, Xing Zheng
Open Journal of Medicinal Chemistry (OJMC) , 2015, DOI: 10.4236/ojmc.2015.54006
Abstract: Resveratrol, a naturally derived stilbene that exists in various foods and beverages, has attracted extensive exploration due to its multiple biological activities, such as anticancer, antioxidant, cardiovascular protection, anti-inflammatory, antiviral, chemopreventive effect, neuroprotective effect, immunomodulation and so on. However, owing to its poor oral bioavailability, the application of resveratrol is greatly restricted. Because of that, a large amount of efforts had been made by researchers on designing its derivatives to obtain compounds with improved efficiency and low toxicity for developing more active drugs for clinical application. In this report, we review the current development of studying on resveratrol derivatives including their properties and activities. Additionally, this article also presents the synthetic routes of correlative resveratrol derivatives.
Effects of Elevated CO2 and Temperature on Yield and Fruit Quality of Strawberry (Fragaria × ananassa Duch.) at Two Levels of Nitrogen Application
Peng Sun, Nitin Mantri, Heqiang Lou, Ya Hu, Dan Sun, Yueqing Zhu, Tingting Dong, Hongfei Lu
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0041000
Abstract: We investigated if elevated CO2 could alleviate the negative effect of high temperature on fruit yield of strawberry (Fragaria × ananassa Duch. cv. Toyonoka) at different levels of nitrogen and also tested the combined effects of CO2, temperature and nitrogen on fruit quality of plants cultivated in controlled growth chambers. Results show that elevated CO2 and high temperature caused a further 12% and 35% decrease in fruit yield at low and high nitrogen, respectively. The fewer inflorescences and smaller umbel size during flower induction caused the reduction of fruit yield at elevated CO2 and high temperature. Interestingly, nitrogen application has no beneficial effect on fruit yield, and this may be because of decreased sucrose export to the shoot apical meristem at floral transition. Moreover, elevated CO2 increased the levels of dry matter-content, fructose, glucose, total sugar and sweetness index per dry matter, but decreased fruit nitrogen content, total antioxidant capacity and all antioxidant compounds per dry matter in strawberry fruit. The reduction of fruit nitrogen content and antioxidant activity was mainly caused by the dilution effect of accumulated non-structural carbohydrates sourced from the increased net photosynthetic rate at elevated CO2. Thus, the quality of strawberry fruit would increase because of the increased sweetness and the similar amount of fruit nitrogen content, antioxidant activity per fresh matter at elevated CO2. Overall, we found that elevated CO2 improved the production of strawberry (including yield and quality) at low temperature, but decreased it at high temperature. The dramatic fluctuation in strawberry yield between low and high temperature at elevated CO2 implies that more attention should be paid to the process of flower induction under climate change, especially in fruits that require winter chilling for reproductive growth.
Deletion of 1.8-kb mRNA of Marek's disease virus decreases its replication ability but not oncogenicity
Aijun Sun, Yanpeng Li, Jingyan Wang, Shuai Su, Hongjun Chen, Hongfei Zhu, Jiabo Ding, Zhizhong Cui
Virology Journal , 2010, DOI: 10.1186/1743-422x-7-294
Abstract: Based on the BAC clone of GX0101, the 1.8-kb mRNA deletion mutant GX0101Δ(A+C) was constructed. The present experiments indicated that GX0101Δ(A+C) retained a low level of oncogenicity, and it showed a decreased replication capacity in vitro and in vivo when compared with its parent virus, GX0101. Further studies in vitro demonstrated that deletion of 1.8-kb mRNA significantly decreased the transcriptional activity of the bi-directional promoter between 1.8-kb mRNA and pp38 genes of MDV.These results suggested that the 1.8-kb mRNA did not directly influence the oncogenesis but related to the replication ability of MDV.Marek's disease (MD) is a contagious lymphoproliferative disease of poultry caused by the highly oncogenic alphaherpesvirus, MDV, which is characteristic by mononuclear infiltration of peripheral nerves, irises, skin and other visceral tissues [1,2]. Among the 100 genes encoded by MDV, three genes including 1.8-kb mRNA, pp38 and meq were considered to be associated with oncogenicity of MDV serotype 1, and they are also unique to MDV [3,4]. Previous studies suggested that meq is involved in lymphocyte transformation [5,6], and pp38 is involved in early cytolytic infection in lymphocytes but not in the induction of tumors [7]. In addition, recent studies indicated that pp38 could also enhance the activity of the bi-directional promoter, which locates between pp38 and 1.8-kb mRNA in the long inverted repeat region of the viral genome, thus influence the replication capacity of the virus [8-10].The 1.8-kb mRNA is unique to MDV and it has no homology with other groups of herpesviruses, and it received attention as a pathogenic determinant following demonstration of the expansion of the 132-bp tandem repeats in the 1.8-kb mRNA region during attenuation of MDV. However, deletion of the two copies of the 132-bp repeat region in a pathogenic MDV demonstrated that the virus was still pathogenic [11]. The transcription map of 1.8-kb mRNA was published in 1989 [12
Deletion of the meq gene significantly decreases immunosuppression in chickens caused by pathogenic marek's disease virus
Yanpeng Li, Aijun Sun, Shuai Su, Peng Zhao, Zhizhong Cui, Hongfei Zhu
Virology Journal , 2011, DOI: 10.1186/1743-422x-8-2
Abstract: In the present study, to investigate whether the Meq-null virus could be a safe vaccine candidate, we constructed a Meq deletion strain, GX0101ΔMeq, by deleting both copies of the Meq gene from a pathogenic MDV, GX0101 strain, which was isolated in China. Pathogenesis experiments showed that the GX0101ΔMeq virus was fully attenuated in specific pathogen-free chickens because none of the infected chickens developed Marek's disease-associated lymphomas. The study also evaluated the effects of GX0101ΔMeq on the immune system in chickens after infection with GX0101ΔMeq virus. Immune system variables, including relative lymphoid organ weight, blood lymphocytes and antibody production following vaccination against AIV and NDV were used to assess the immune status of chickens. Experimental infection with GX0101ΔMeq showed that deletion of the Meq gene significantly decreased immunosuppression in chickens caused by pathogenic MDV.These findings suggested that the Meq gene played an important role not only in tumor formation but also in inducing immunosuppressive effects in MDV-infected chickens.Marek's disease (MD) is a neoplastic disease of chickens, which is caused by the lymphotropic alphaherpesvirus, MD virus (MDV). MD is characterized by the development of T-cell lymphomas and lymphocytic infiltration of peripheral nerves, skin, skeletal muscle and visceral organs [1-3]. Infection with MDV and subsequent development of MD is frequently associated with immunosuppression, which is considered to be an integral aspect of MD pathogenesis that ultimately leads to the death of many chickens in a number of cases [4,5].To search for oncogene(s), early studies focused on the genes expressed in tumor cells. It has been shown that the transcriptional activity of MDV in tumor cells was confined to the RL regions. And Meq [6], pp38 [7] and the BamHI-H family which includes a 132 bp repeating region [8-10] are unique to MDV among the RL-encoded genes. Inoculation of MD-susceptible bi
Hf isotopic composition of zircons from the Huashan-Guposhan intrusive complex and their mafic enclaves in northeastern Guangxi: Implication for petrogenesis
KuiDong Zhao,ShaoYong Jiang,JinChu Zhu,Liang Li,BaoZhang Dai,YaoHui Jiang,HongFei Ling
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-009-0314-0
Abstract: High precision zircon U-Pb dating indicates that main intrusive bodies (Tong’an, Niumiao, Huashan, Lisong), and a mafic microgranular enclave in the Huashan-Guposhan complex were formed at 160–163 Ma. The Hf(t) values of zircons from the Huashan granite vary from 2.8 to +0.3 and those from the Lisong granite vary from 2.3 to +0.3, which are obviously different with those values (+2.6 to +7.4) of the mafic enclaves from the Lisong granite. These Hf isotopic data indicate that the mafic enclaves and host granites were crystallized from different sources of magmas, providing evidence for mafic-felsic magma mixing processes. The highest Hf(t) value of zircons from the mafic enclaves is up to +7.4, indicating that the mafic magma was originated from a relatively depleted mantle source. Studies on regional geology and the contemporaneous mafic and alkaline rocks in this area indicate that the mafic magma was not originated from reworking of basaltic juvenile crust, but from partial melting of the mantle. However, it remains to be resolved whether the mafic magma was derived from partial melting of the asthenosphere or the lithospheric mantle. The Huashan granite and the Lisong granite were formed from hybrid magma of mantle-derived and crust-derived magmas, and the mafic enclaves are considered as remains of mantle-derived magma during mixing processes. The Hf(t) values of zircons from the Niumiao diorite vary from 1.1 to +2.1, and those from the Tong’an quartz monzonite vary from 1.7 to +1.7. These values are lower than those from the mafic enclaves, suggesting that the diorite and monzonite were formed from different source-derived magma with the mafic enclaves. The Hf(t) values for the Niumiao diorite and the Tong’an monzonite are only slightly higher than those for the Hushan granite and the Lisong granite. Abundant mafic enclaves also occur in the Niumiao diorite and in the Tong’an monzonite. Thus, we suggest that the Niumiao diorite and the Tong’an monzonite were probably also formed from the same hybrid magma as the granites but come through less degree of fractional crystallization and crustal contamination. The strong mantle-derived and crust-derived magma mixing caused by an intense crustal extension and thinning in the Mid-Late Jurassic may be the major mechanism for generating the diorites and granites in southeastern Hunan and northeastern Guangxi belt in South China.
SHRIMP zircon U-Pb ages and tectonic implications for Indosinian granitoids of southern Zhuguangshan granitic composite, South China
Ping Deng,JiShun Ren,HongFei Ling,WeiZhou Shen,LiQiang Sun,Ba Zhu,ZhengZhong Tan
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-011-4951-8
Abstract: The large southern Zhuguangshan granitic batholith composite consists of granites with ages varying from the Caledonian through Indosinian to Yanshanian. Based on K-Ar dating data, the ages of the major parts of this composite were previously regarded as Yanshanian. In this study, the SHRIMP zircon U-Pb dating method has been adopted for six plutons, Ledong, Longhuashan, Dawozi, Zhaidi, Baiyun and Jiangnan, in the southern Zhuguangshan composite, in which the four plutons other than Baiyun and Jiangnan were previously regarded as Yanshanian granites. Magmatic zircons from these six plutons, dated by this study, have yielded ages of 239±5 Ma (MSWD = 2.5), 239±5 Ma (MSWD = 2.5), 239±2 Ma (MSWD = 1.7), 239±4 Ma (MSWD = 3.2), 231±2 Ma (MSWD = 0.81) and 231±3 Ma (MSWD = 1.8), respectively. The results indicate that these plutons were formed by early Indosinian magmatism. Geochemical characteristics suggest that these granites were formed in an extensional tectonic environment. Therefore, the Indosinian period granites in the southern Zhuguangshan composite were formed by partial melting of the Paleo-Mesoproterozoic crustal components during the collapse of thickened lithosphere after the collision between the South China and Indosinian plates.
Combined Inhibition of Epidermal Growth Factor Receptor and Cyclooxygenase-2 Leads to Greater Anti-tumor Activity of Docetaxel in Advanced Prostate Cancer
Jianzhong Lin, Hongfei Wu, Hui Shi, Wei Pan, Hongbo Yu, Jiageng Zhu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076169
Abstract: The epidermal growth factor receptor (EGFR) and cyclooxygenase-2(COX-2) play a critical role in disease progression, relapse and therapeutic resistance of advanced prostate cancer (PCa). In this paper, we evaluated, for the first time, the therapeutic benefit of blocking EGRF and/or COX-2 (using gefitinib and NS-398, respectively) in terms of improving the efficacy of the conventional clinical chemotherapeutic drug docetaxel in vitro and vivo. We showed that EGFR and COX-2 expression was higher in metastatic than non-metastatic PCa tissues and cells. Docetaxel, alone or in combination with gefitinib or NS-398, resulted in a small decrease in cell viability. The three drug combination decreased cell viability to a greater extent than docetaxel alone or in combination with gefitinib or NS-398. Docetaxel resulted in a modest increase in apoptotic cell in metastatic and non-metastatic cell lines. NS-398 markedly enhanced docetaxel-induced cell apoptosis. The combination of the three drugs caused even more marked apoptosis and resulted in greater suppression of invasive potential than docetaxel alone or in association with gefitinib or NS-398. The combination of all three drugs also resulted in a more marked decrease in NF-ΚB, MMP-9 and VEGF levels in PC-3M cells. These in vitro findings were supported by in vivo studies showing that docetaxel in combination with gefitinib and NS-398 was significantly more effective than any individual agent. Based on previous preclinical research, we conclude that simultaneously blocking EGFR and COX-2 by gefitinib and NS-398 sensitizes advanced PCa cells to docetaxel-induced cytotoxicity.
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