检索结果-南通市图书馆

The instability of a stable metal-organic framework in amino acid solutions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2022年第7期15卷 6607-6612页

作者： Yiran Wang Jinglin Yin Weicheng Cao Yao Fu Xueqian Kong Department of Chemistry Zhejiang UniversityHangzhou 310027China Department of Rehabilitation Sir Run Run Shaw HospitalSchool of MedicineZhejiang UniversityHangzhou 310027China Key Laboratory of Excited-State Materials of Zhejiang Province Zhejiang UniversityHangzhou 310027China

Metal–organic frameworks(MOFs)are being investigated as the potential materials for future drug delivery and gene therapy systems thanks to their tunable functionality and biocompatibility.However,the structure of MOFs could be altered in a biological environment or in a buffer solution.It is of great importance to evaluate the stability of MOFs and understand the degradation processes for the sake of the biomedical applications.In this work,we investigate the stability of UiO-66,a generally-perceived stable MOF,in different amino acid solutions.We find that UiO-66 loses crystallinity in relatively mild basic conditions(when pH≥9)in the presence of amino acids.The instability is more pronounced in the lysine and arginine solutions which have stronger basicity.It can be attributed to the accelerated ligand exchange of UiO-66 under basic conditions.With a combination of techniques,we show that the amino acids can replace the organic linkers and form zirconium-amino acid complexes.Our research reveals one possible mechanism of MOF degradation in biological environment,yet such degradability could be also an important designable property for MOFs in biomedical applications.

关键词： metal-organic frameworks stability amino acids solid-state nuclear magnetic resonance(NMR) biomedical applications

Biosynthesis and Regulation of Salicylic Acid and N-Hydroxypipecolic Acid in Plant Immunity

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Molecular Plant 2020年第1期13卷 31-41页

作者： Weijie Huang Yiran Wang Xin Li Yuelin Zhang Department of Botany University of British ColumbiaVancouverBC V6T 1Z4Canada Michael Smith Laboratories University of British ColumbiaVancouverBC V6T 1Z4Canada

Salicylic acid(SA)has long been known to be essential for basal defense and systemic acquired resistance(SAR).N-Hydroxypipecolic acid(NHP),a recently discovered plant metabolite,also plays a key role in SAR and to a lesser extent in basal resistance.Following pathogen infection,levels of both compounds are dramatically increased.Analysis of SA-or SAR-deficient mutants has uncovered how SA and NHP are biosynthesized.The completion of the SA and NHP biosynthetic pathways in Arabidopsis allowed better understanding of how they are regulated.In this review,we discuss recent progress on SA and NHP biosynthesis and their regulation in plant immunity.

关键词： plant immunity SAR SA NHP pipecolic acid

Numerical investigation of flow over a two-dimensional square cylinder with a synthetic jet generated by a bi-frequency signal

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2022年第10期43卷 1569-1584页

作者： yiran LU Yuan QU Jiangsheng wang Jinjun wang Fluid Mechanics Key Laboratory of Education Ministry Beihang UniversityBeijing 100191China

The flow around a square cylinder with a synthetic jet positioned at the rear surface is numerically investigated with the unsteady Reynolds-averaged Navier-Stokes(URANS)method.Instead of the typical sinusoidal wave,a bi-frequency signal is adopted to generate the synthetic jet.The bi-frequency signal consists of a basic sinusoidal wave and a high-frequency wave.Cases with various amplitudes of the high-frequency component are simulated.It is found that synthetic jets actuated by bi-frequency signals can realize better drag reduction with lower energy consumption when appropriate parameter sets are applied.A new quantity,i.e.,the actuation efficiency Ae,is used to evaluate the controlling efficiency.The actuation efficiency Ae reaches its maximum of 0.2668 when the amplitude of the superposed high-frequency signal is 7.5%of the basic signal.The vortex structures and frequency characteristics are subsequently analyzed to investigate the mechanism of the optimization of the bi-frequency signal.When the synthetic jet is actuated by a single-frequency signal with a characteristic velocity of 0.112 m/s,the wake is asymmetrical.The alternative deflection of vortex pairs and the peak at half of the excitation frequency in the power spectral density(PSD)function are detected.In the bi-frequency cases with the same characteristic velocity,the wake gradually turns to be symmetrical with the increase in the amplitude of the high-frequency component.Meanwhile,the deflection of the vortex pairs and the peak at half of the excitation frequency gradually disappear as well.

关键词： synthetic jet flow control signal superposition vortex dynamics

Trends and Challenges for Population Health and Migration-China,2015−2050

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

China CDC weekly 2020年第28期2卷 520-524,I0004页

作者： Yanan Luo Chao Guo Yiran Wang Xiaoying Zheng Institute of Population Research Peking UniversityBeijingChina APEC Health Science Academy Peking UniversityBeijingChina

What is already known about this topic?Along with the quick change of society and health transformation,as well as the continued expansion of urbanization,the health risk and its variation of migrants in China would became more complicated.What is added by this report?Although a decreasing net migration flow trend was presented from 2015 to 2050,an increasing pace of aging and younger-age trend of migrants would pose serious challenges for population health in China.Deepening aging trend of migrants contributes to the increment of the disease burden of non-communicable diseases(NCDs)and disabilities,and the upward trend of young-age migrant patients with infectious diseases remain a threat to the future intervention and prevention of infectious diseases.What are the implications for public health practice?Health policies to eliminate the adverse effects of migration on population health should pay more attention to meet the health care demands of highly vulnerable migrant populations,such as very older and very young migrants.

关键词： Population trend younger

Mg-Al-hydrotalcite with alkaline sites protects Ni/KIT-6 from formation of amorphous coke in glycerol steam reforming via tailoring reaction intermediates

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2024年第4期18卷 25-39页

作者： Yunyu Guo Yiran Wang Yuewen Shao Shu Zhang Yi wang Song Hu Jun Xiang Xun Hu School of Material Science and Engineering University of JinanJinan 250022China Joint International Research Laboratory of Biomass Energy and Materials College of Materials Science and EngineeringNanjing Forestry UniversityNanjing 210037China State Key Laboratory of Coal Combustion Huazhong University of Science and TechnologyWuhan 430074China

During steam reforming,the performance of a catalyst and amount/property of coke are closely related to reaction intermediates reaching surface of a catalyst.Herein,modification of reaction intermediates by placing Mg-Al-hydrotalcite above Ni/KIT-6 catalyst in steam reforming of glycerol was conducted at 300 to 600°C.The results revealed that the catalytic activity of Ni/KIT-6 in the lower bed was enhanced with either Mg1-Al5-hydrotalcite(containing more acidic sites)or Mg5-Al1-hydrotalcite(containing more alkaline sites)as upper-layer catalyst.The in situ infrared characterization of steam reforming demonstrated that Mg-Al-hydrotalcite catalyzed the deoxygenation of glycerol,facilitating the reforming of the partially deoxygenated intermediates over Ni/KIT-6.Mg-Al-hydrotalcite as protective catalyst,however,did not protect the Ni/KIT-6 from formation of more coke.Nonetheless,this did not lead to further deactivation of Ni/KIT-6 while Mg5-Al1-hydrotalcite even substantially enhanced the catalytic stability,even though the coke was much more significant than that in the use of single Ni/KIT-6(52.7%vs.28.6%).The reason beneath this was change of the property of coke from more aliphatic to more aromatic.Mg5-Al1-hydrotalcite catalyzed dehydration of glycerol,producing dominantly reaction intermediates bearing C=C,which formed the catalytic coke of with carbon nanotube as the main form with smooth outer walls as well as higher aromaticity,C/H ratio,crystallinity,crystal carbon size,thermal stability,and resistivity toward oxidation on Ni/KIT-6 in the lower bed.In comparison,the abundance of acidic sites on Mg1-Al5-hydrotalcite catalyzed the formation of more oxygen-containing species,leading to the formation of carbon nanotubes of rough surface on Ni/KIT-6.

关键词： steam reforming of glycerol Mg-Alhydrotalcite sacrificial catalyst reaction intermediates property of coke

Rational design of bimetallic atoms supported on C3N monolayer to break the linear relations for efficient electrochemical nitrogen reduction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2022年第9期15卷 8656-8664页

作者： Riming Hu Yanan Yu Yongcheng Li Yiran Wang Jiaxiang Shang Yong Nie Xuchuan Jiang Institute for Smart Materials&Engineering University of JinanJinan 250022China Shandong college of Tourism and Hospitality Jinan 250200China Qinghai Provincial Key Laboratory of New Light Alloys Qinghai Provincial Engineering Research Center of High-Performance Light Metal Alloys and FormingQinghai UniversityXining 810016China School of Materials Science and Engineering Beihang UniversityBeijing 100191China

Linear relations between the adsorption free energies of nitrogen reduction reaction(NRR)intermediates limit the catalytic activity of single atom catalysts(SACs)to reach the optimal region.Significant improvements in NRR activity require the balance of binding strength of reaction intermediates.Herein,we have investigated the C_(3)N-supported monometallic(M/C_(3)N)and bimetallic(M_(1)M_(2)/C_(3)N)atoms for the electrochemical NRR by using density functional theory(DFT)calculations.The results show that this linear relation does exist for SACs because all the intermediates bind to the same site on M/C_(3)N.But the synergistic effect of the two atoms in M_(1)M_(2)/C_(3)N can create a more flexible adsorption site for intermediates,which results in the decoupling of adsorption free energies of key intermediates.Subsequently,the fundamental limitation of scaling relations on limiting potentials is broken through.Most notably,the optimal limiting potential is increased from−0.63 V for M/C_(3)N to−0.20 V for M_(1)M_(2)/C_(3)N.In addition,the presence of bimetallic atoms can also effectively inhibit the hydrogen evolution reaction(HER)as well as improve the stability of the catalysts.This study proposes that the introduction of bimetallic atoms into C_(3)N is beneficial to break the linear relations and develop efficient NRR electrocatalysts.

关键词： nitrogen reduction reaction linear relations bimetallic atoms C_(3)N density functional theory

Repeatability and reproducibility of corneal higher-order aberrations measurements after small incision lenticule extraction using the Scheimpfug-Placido topographer

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Eye and Vision 2024年第1期10卷 1-9页

作者： Rui Ning Rongrong Gao David PPiñero Jun Zhang Qingyi Gao Yili Jin Yiran Wang Chenxiao wang Jinhai Huang Eye Hospital and School of Ophthalmology and Optometry Wenzhou Medical UniversityWenzhouZhejiangChina Eye Institute and Department of Ophthalmology Eye and ENT HospitalFudan UniversityShanghaiChina Group of Optics and Visual Perception Department of OpticsPharmacology and AnatomyUniversity of AlicanteAlicanteSpain NHC Key Laboratory of Myopia(Fudan University) Key Laboratory of MyopiaChinese Academy of Medical SciencesShanghaiChina Shanghai Research Center of Ophthalmology and Optometry ShanghaiChina

Background:To evaluate the precision of corneal higher-order aberrations measurements after small incision lenticule extraction(SMILE)using the Sirius Scheimpfug-Placido topographer(CSO,Italy).Methods:Seventy-fve eyes from 75 postoperative subjects were included in this prospective study.Three consecutive corneal aberrometric measurements were obtained with the Scheimpfug-Placido topographer by two experienced operators to assess intra-and inter-observer reproducibility.The within-subject standard deviation(Sw),test-retest repeatability(TRT)and the intraclass correlation coefcient(ICC)were calculated.Results:For intraobserver repeatability of anterior and total corneal aberrations,all ICCs were more than 0.922,except for trefoil(0.722 to 0.768).The ICCs of total root mean square(RMS),coma Z(3,±1),and spherical aberration Z(4,0)were over 0.810 while higher-order RMS,trefoil Z(3,±3),and astigmatism II Z(4,±2)were below 0.634 for posterior corneal surface aberrations.All Sw values for all types of aberrations were equal to or below 0.07μm.Regarding interobserver reproducibility,all TRT values were no more than 0.12μm,0.05μm,and 0.11μm for anterior,posterior,and total corneal aberrations,respectively.The ICC values ranged from 0.875 to 0.989,from 0.686 to 0.976 and over 0.834 for anterior,posterior,and total corneal aberrations,respectively.Conclusions:The repeatability of measurements of anterior and total corneal aberrations with the Sirius system in corneas after SMILE surgery was high,except for trefoil.There was some variability in posterior corneal aberrometric measurements.High reproducibility of corneal aberrometric measurements was observed between measurements of both examiners,except for trefoil,with poor to moderate reproducibility.

关键词： Sirius Higher-order aberrations Repeatability Reproducibility Small incision lenticule extraction

Hyperspectral Image Classification Based on Unsupervised Heterogeneous Domain Adaptation CycleGan

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2020年第4期29卷 608-614页

作者： wang Xuesong LI yiran CHENG Yuhu School of Information and Control Engineering China University of Mining and Technology Xuzhou Key Laboratory of Artificial Intelligence and Big Data

Aiming at the difficulty of obtaining sufficient labeled Hyperspectral image(HSI) data and the inconsistent feature distribution of different HSIs, a novel Unsupervised heterogeneous domain adaptation CycleGan(UHDAC) is proposed by using CycleGan to capture the transferable features in the absence of similar data.On the one hand, the two-way mapping is used to find the internal relationship between the source and target domain data,while the two-way adversary is used to constrain the source and target domain features, realizing the alignment of feature distributions.On the other hand, the CORAL loss function is introduced to minimize the distance between the second-order statistical difference between the source and target domain features, so as to solve the insufficient constraint of mapping relationship caused by the low consistency of HSI data structure in different domains.Experiments on three real HSI datasets show that UHDAC can effectively realize the unsupervised classification of target domain HSI with high classification accuracy by using the labeled HSI data in the source domain.

关键词： Unsupervised Heterogeneous Domain adaptation CycleGan Hyperspectral image Classification

Differential Coherent Algorithm Based on Fast Navigation-Bit Correction for Airborne GNSS-R Software Receivers

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2013年第1期18卷 88-99页

作者： Yiran Wang Bo Zhang Dingrong Shao School of Electronic Information Engineering Beihang University

Signals from the Global Navigation Satellite System （GNSS） scatter over the sea surface resulting in relatively low Signal-to-Noise Ratios （SNR）. A differential coherent algorithm is given here to improve the SNR and reduce the performance degradation due to the Squaring-Loss and the navigation-bit effect. The algorithm uses fast navigation-bit correction for Delay-Doppler Maps （DDM） in airborne Global Navigation Satellite Signal Reflectometry （GNSS-R） software receivers. The system model is introduced with an analysis of the statistical properties with simulations to support the theoretical analysis. Field experiments with real airborne receivers then demonstrate the effectiveness of this algorithm. Comparisons with test results show that this algorithm offers a significant SNR gain over conventional algorithms.

关键词： satellite navigation signal processing Global Navigation Satellite Signal Reflectometry （GNSS-R） Delay-Doppler maps differential coherence signal-to-noise ratio