马来酰亚胺-丙烯酸酯共聚物的制备及在热纳米压印抗蚀剂的应用

马来酰亚胺与丙烯酸酯通过自由基溶液聚合制备了马来酰亚胺-丙烯酸酯共聚物(P(AA-MI-AHA))。根据凝胶渗透色谱,共聚物的多分散系数低于2,表现出窄的分子量分布特点;根据热失重分析和差示扫描量热分析,聚合物热分解温度高于140℃,玻璃化温度约为128℃,展现出较好的热稳定性。将共聚物用作热纳米压印抗蚀剂材料,研究了共聚物的微纳米图案复制能力。扫描电子显微镜观察到排列规整的条纹图案,分辨率约为100 nm。综上表明,所得马来酰亚胺-丙烯酸酯共聚物用作热纳米压印抗蚀剂材料展现出较好的图像复制能力。

A Comparison of Citation Disciplinary Structure in Science between the G7 Countries and the BRICS Countries

Purpose： This study aims to compare the characteristics of citation disciplinary structure between the G7 countries and the BRICS countries.Design/Methodology/Approach： In this contribution, which uses about 1 million Web of Science publications and two publications years（1993 and 2013）, we compare the G7 countries and the BRICS countries with regard to this type of structure. For the publication year 2013, cosine similarity values regarding the citation disciplinary structures of these countries（and of nine other countries） were used as input to cluster analysis. We also obtained cosine similarity values for a given country and its citation disciplinary structures across the two publication years. Moreover, for the publication year 2013, the within-country JeffreysMatusita distance between publication and citation disciplinary structure was measured. Research limitations： First, the citation disciplinary structures of countries depend on multiple and complex factors. It is therefore difficult to completely explain the formation and change of the citation disciplinary structure of a country. This study suggests some possible causes, whereas detailed explanations might be given by future research. Second, the length of the citation window used in this study is three years. However, scientific disciplines differ in their citation practices. Comparison between citations across disciplines using the same citation window length may affect the citation discipline structure results for some countries.Practical limitations： First, the results of this study are based on the WoS database. However, in this database some fields are covered to a greater extent than others, which may affect the results for the citation discipline structure for some studied countries. In future research, we might repeat this study using another database（like Scopus） and, in that case, we would like to make comparisons between the two outcomes. Second, the use of a constant journal setyielded that a large share of the journals covered by WoS year 2013 is ignored in the study. Thus, disciplinary structure is studied based on a quite restricted set of publications. The three mentioned limitations should be kept in mind when the results of this study are interpreted.Originality/value： Disciplinary structure on country level is a highlighted topic for the S＆T policy makers, especially for those come from developing countries. This study observes the disciplinary structure in the view of academic impact, and the result will provide some evidence to make decision for the discipline strategy and funding allocation. Besides, JeffreysMatusita distance is introduced to measure the similarity of citation disciplinary structure and publication disciplinary structure. By applying this measure, some new observations were drawn, for example, ＂Based on the comparison of publication disciplinary structure and citation disciplinary structure, the paper finds most BRICS counties have less impact with more publications＂.Findings： The outcome of the cluster analysis indicates that the G7 countries and BRICS countries are quite heterogeneous regarding their citation disciplinary structure. For a majority of the G7 countries, the citation disciplinary structure tend to be more stable compared to BRICS countries with regard to the years 1993 and 2013. Most G7 countries, with United States as an exception, turned out to have lower values on the Jeffreys-Matusita distance than BRICS countries, indicating a higher degree of heterogeneity between the publication and the citation disciplinary structure for the latter countries. In other words, BRICS countries still receive much less citations in most disciplines than their publication output would suggest. G7 countries can still expect more citations than is to be expected based on their publication output, thereby generating relatively more impact than BRICS countries.

Enhanced lysosome escape mediated by 1,2-dicarboxylic-cyclohexene anhydride-modified poly-L-lysine dendrimer as a gene delivery system

Antisense oligodeoxynucleotide(ASODN)can directly interfere a series of biological events of the target RNA derived from tumor cells through Watson-Crick base pairing,in turn,plays antitumor therapeutic roles.In the study,a novel HIF-1αASODN-loaded nanocomposite was formulated to efficiently deliver gene to the target RNA.The physicochemical properties of nanocomposite were characterized using TEM,FTIR,DLS and zeta potentials.The mean diameter of resulting GEL-DGL-FA-ASODN-DCA nanocomposite was about 170–192 nm,and according to the agarose gel retardation assay,the loading amount of ASODN accounted for 166.7 mg/g.The results of cellular uptake showed that the nanocomposite could specifically target to HepG2 and Hela cells.The cytotoxicity assay demonstrated that the toxicity of vectors was greatly reduced by using DCA to reversibly block the cationic DGL.The subcellular distribution images clearly displayed the lysosomal escape ability of the DCA-modified nanocomposite.In vitro exploration of molecular mechanism indicated that the nanocomposite could inhibit m RNA expression and HIF-1αprotein translation at different levels.In vivo optical images and quantitative assay testified that the formulation accumulated preferentially in the tumor tissue.In vivo antitumor efficacy research confirmed that this nanocomposite had significant antitumor activity and the tumor inhibitory rate was 77.99%.These results manifested that the GEL-DGL-FA-ASODNDCA nanocomposite was promising in gene therapeutics for antitumor by interacting directly with target RNA.

Document Type Profiles in Nature, Science, and PNAS： Journal and Country Level

Purpose： In this contribution, we want to detect the document type profiles of the three prestigious journals Nature, Science, and Proceedings of the National Academy of Sciences of the United States （PNAS） with regard to two levels： journal and country. Design/methodology/approach： Using relative values based on fractional counting, we investigate the distribution of publications across document types at both the journal and country level, and we use （cosine） document type profile similarity values to compare pairs of publication years within countries. Findings： Nature and Science mainly publish Editorial Material, Article, News Item and Letter, whereas the publications of PNAS are heavily concentrated on Article. The shares of Article for Nature and Science are decreasing slightly from 1999 to 2014, while the corresponding shares of Editorial Material are increasing. Most studied countries focus on Article and Letter in Nature, but on Letter in Science and PNAS. The document type profiles of some of the studied countries change to a relatively large extent over publication years. Research limitations： The main limitation of this research concerns the Web of Science classification of publications into document types. Since the analysis of the paper is based on document types of Web of Science, the classification in question is not free from errors, and the accuracy of the analysis might be affected.Practical implications： Results show that Nature and Science are quite diversified with regard to document types. In bibliometric assessments, where publications in Nature and Science play a role, other document types than Article and Review might therefore be taken into account. Originality/value： Results highlight the importance of other document types than Article and Review in Nature and Science. Large differences are also found when comparing the country document type profiles of the three journals with the corresponding profiles in all Web of Science journals.

jdisHow does the Research Capacity Gap among Institutions Change over Time?

Recent investigation has reported that the richest 10%of the world population now owns 76%of all wealth due to COVID-19,indicating a wide gap between the rich and the poor across the globe(World Economic Forum,2022).This disparity also prevails in science,where a few prominent institutions publish most impactful papers,while the rest majority are inconspicuous.

Study on Voltage Sag Detection of Wind Power System Based on HHT

For the output of wind power system has the characteristics of randomness, volatility and intermittence, the voltage of wind power system fluctuates frequently and voltage sag is one of the most common voltage fluctuations in wind power system. For the problem of voltage sag of wind power system, the limitations of the detection methods such as the square detection method, the half-wave RMS detection method and wavelet transform are summed up, and a new detecting method named Hilbert-huang Transform(HHT) is put forward in this paper, which can detect the voltage sag accurately and timely. In order to solve the problem of end effect in the process of empirical mode decompostion (EMD), a self-adaptive method named improved waveform matching is applied in dealing with the end issue. Voltage fluctuations are reflected by two parameters named voltage amplitude and frequency of each intrinsic mode function (IMF) in HHT. The practicality of the method is verified by Matlab simulation.

Radiological insights of ectopic thyroid in the porta hepatis: A case report and review of the literature

BACKGROUND Ectopic thyroid is defined as a rare developmental anomaly where thyroid tissues are atypically found in locations other than its normal anatomical position:Anterolateral to the second,third,and fourth tracheal cartilages.An intemperate descent or a migration failure of the thyroid anlage results in sub-diaphragmatic thyroid ectopia,a sparse clinical entity.CASE SUMMARY This case portrays a 63-year-old female patient presenting with chronic abdominal discomfort at a local hospital whereby a computed tomography(CT)scan revealed a well-defined mass in the hepatic entrance.For further examination,the patient underwent a CT scan with contrast,magnetic resonance imaging(MRI),and CT-angiography(CTA)at our department.The CT scan showed a welldefined and high attenuated mass measuring 43 mm×38 mm in the hepatic entrance with calcification.The CTA revealed an additional finding:Blood supply to the mass from the right hepatic artery.MRI of the upper abdomen demonstrated a mass with mixed signal intensity on T1 and T2 weighted images in the hepatic entrance.The patient underwent surgery with resection of the mass which was sent for histopathology.Ectopic thyroid at the level of porta hepatis with nodules was the definitive diagnosis since histopathological report revealed presence of thyroid tissue in the resected liver mass.CONCLUSION This case delivers a rare insight of pre-operative radiological imaging of an ectopic thyroid located in the liver.These findings can aid in narrowing down potential differential diagnosis when managing a patient with those subsequent findings.

Suggestions for flying qualities requirements of autonomous control unmanned combat aerial vehicles

There is a lack of quantitative flying qualities assessment requirements for unmanned combat aerial vehicles.The mission-oriented flying qualities evaluation approach can make up for the deficiencies of existing flying qualities specifications.Considering the control characteristics and mission requirements of autonomous control unmanned combat aerial vehicles,flying qualities assessment tasks are designed and performance standards are developed on the basis of manned aircraft flying qualities assessment tasks.Multiple sets of mathematical simulations are performed by varying the control law parameters to investigate the relationship between the control law parameter values,closed-loop aircraft system characteristics and flying qualities levels.The simulation results and closed-loop frequency domain analysis show that the existing flying qualities guidelines for manned aircraft are not fully applicable to the flying qualities assessment of autonomous control unmanned combat aerial vehicles.It is found that the combination of the bandwidth and the phase at the bandwidth frequency can define the flying qualities requirements of autonomous control unmanned aerial vehicles.The criterion boundaries of different levels are given,and the physical reasons for the formation of boundary are analysed.Our results can be applied to flying qualities assessment and design of flight control laws for autonomous control unmanned combat aerial vehicles.

Bolt insertion damage and mechanical behaviors investigation of CFRP/CFRP interference fit bolted joints

Interference fit has advantages in improving fatigue behaviors of composite bolted joints,however, interference fit bolt insertion tends to cause damages in laminates weakening joint mechanical properties. Therefore, an experimental study was conducted to investigate bolt insertion damages of Carbon Fiber Reinforced Polymer(CFRP)/CFRP interference fit bolted joints.Mechanical behaviors of joints were also evaluated experimentally under both quasi-static loads and cyclic loads. Scanning Electron Microscope(SEM) and high-resolution X-ray micro-CT scan were used to examine micro damages in laminates. Damage and failure behaviors of joints were characterized. The results demonstrated that the hole entrance in upper laminate and the laminate boundary near the hole wall were the most critical regions for damages during bolt insertions. However, the influence of those damages on quasi-static failure loads and fatigue failure modes of joints was minimal. Delamination and matrix cracking occurred first in laminates following fiber and matrix fracture in quasi-static tensile tests. Interference fit could improve the fatigue resistance of the laminate hole, however, the bolt seemed to suffer a more critical local fatigue loading condition.This paper can contribute to composite structure designs, especially in understanding damage and failure behaviors of composite bolted joints.

Spatial distribution of IL4 controls iNKT cell-DC crosstalk in tumors

The spatiotemporal distribution of cytokines orchestrates immune responses in vivo,yet the underlying mechanisms remain to be explored.We showed here that the spatial distribution of interleukin-4(IL4)in invariant natural killer T(iNKT)cells regulated crosstalk between iNKT cells and dendritic cells(DCs)and controlled iNKT cell-mediated T-helper type 1(Th1)responses.The persistent polarization of IL4 induced by strong lipid antigens,that is,α-galactosylceramide(αGC),caused IL4 accumulation at the immunological synapse(IS),which promoted the activation of the IL4R-STAT6(signal transducer and activator of transcription 6)pathway and production of IL12 in DCs,which enhanced interferon-γ(IFNγ)production in iNKT cells.Conversely,the nonpolarized secretion of IL4 induced by Th2 lipid antigens with a short or unsaturated chain was incapable of enhancing this iNKT cell-DC crosstalk and thus shifted the immune response to a Th2-type response.The nonpolarized secretion of IL4 in response to Th2 lipid antigens was caused by the degradation of Cdc42 in iNKT cells.Moreover,reduced Cdc42 expression was observed in tumorinfiltrating iNKT cells,which impaired IL4 polarization and disturbed iNKT cell-DC crosstalk in tumors.

Metal-organic framework membranes: From synthesis to electrocatalytic applications

Metal-orga nic frameworks(MOFs),as an emerging family of porous inorga nic-organic crystal materials,exhibit widely applications in gas storage and separation,drug release,sensing,and catalysis,owing to easily adjustable pore sizes,uniformly distributed metal centers,high surface areas,and tunable functionalities.However,MOF crystal powders are usually difficult to be directly applied into specific devices because of their brittleness,insolubility and low compatibility.Therefore,to expand versatile MOF membranes with robustness and operational flexibility is urgent to satisfy practical applications.Although numerous reports have reviewed the synthesis and applications of MOF membranes,relatively few reports the electrocatalytic properties based on MOF membranes.Herein,this mini-review provides an overview of preparation of MOF membranes,including directed synthesis,secondary growth and electrochemical deposition method.Meanwhile,fabrication of ultrathin 2D MOF nanosheets those can be also defined as a kind of nanoscale MOF membranes is also mentioned.Electrocatalytic performance of oxygen reduction reaction(ORR),oxygen evolution reaction(OER),hydrogen evolution reaction(HER)and CO2 reduction reaction(CO2RR) for diverse MOF membranes/nanosheets and their derivatives are introduced.

Sliding mode control design for oblique wing aircraft in wing skewing process

When the wing of Oblique Wing Aircraft(OWA) is skewed, the center of gravity, inertia and aerodynamic characteristics of the aircraft all significantly change, causing an undesirable flight dynamic response, affecting the flying qualities, and even endangering the flight safety. In this study,the dynamic response of an OWA in the wing skewing process is simulated, showing that the threeaxis movements of the OWA are highly coupled and present nonlinear characteristics during the wing skewing. As the roll control efficiency of the aileron decreases due to the shortened control arm in an oblique configuration, the all-moving horizontal tail is used for additional roll and the control allocation is performed based on minimum control energy. Given the properties of pitchroll-yaw coupling and control input and state coupling, and the difficulty of establishing an accurate aerodynamic model in the wing skewing process due to unsteady aerodynamic force, a multi-loop sliding mode controller is formulated by the time-scale separation method. The closed-loop simulation results show that the asymmetric aerodynamics can be balanced and that the velocity and altitude of the aircraft maintain stable, which means that a smooth transition is obtained during the OWA's wing skewing.

Suggestion for aircraft flying qualities requirements of a short-range air combat mission

Owing to the lack of a direct link with the operations in short-range air combat,conventional aircraft flying qualities criteria are inappropriate to guide the design of a task-tailored flight control law.By applying the mission-oriented flying qualities evaluation approach,various aircraft with different control law parameters are evaluated on a ground-based simulator.This paper compares the evaluation results with several conventional flying qualities criteria,and discusses the appropriate parameter combination to reflect the flying qualities requirements of short-range air combat.The comparison and analysis show that a short-range air combat mission requires a higher minimum short period mode natural frequency and a smaller maximum roll mode time constant,and allows a lower minimum pitch attitude bandwidth and a higher maximum short period mode damp ratio than those of conventional flying qualities criteria.Furthermore,a combination of the pitch attitude bandwidth,the pitch attitude magnitude at the bandwidth frequency,and the pitch attitude transfer function gain can define the flying qualities requirements of short-range air combat.The new metric can successfully predict the flying quality levels of aircraft in a short-range air combat mission.

Three-axis coupled flight control law design forflying wing aircraft using eigenstructure assignment method

Due to elimination of horizontal and vertical tails,flying wing aircraft has poor longitudinal and directional dynamic characteristics.In addition,flying wing aircraft uses drag rudders for yaw control,which tends to generate strong three-axis control coupling.To overcome these problems,a flight control law design method that couples the longitudinal axis with the lateraldirectional axes is proposed.First,the three-axis coupled control augmentation structure is specified.In the structure,a‘‘soft/hard"cross-connection method is developed for three-axis dynamic decoupling and longitudinal control response decoupling from the drag rudders;maneuvering turn angular rate estimation and subtraction are used in the yaw axis to improve the directional damping.Besides,feedforward control is adopted to improve the maneuverability and control decoupling performance.Then,detailed design methods for feedback and feedforward control parameters are established using eigenstructure assignment and model following technique.Finally,the proposed design method is evaluated and compared with conventional method by numeric simulations.The influences of control derivatives variation of drag rudders on the method are also analyzed.It is demonstrated that the method can effectively improve the dynamic characteristics of flying wing aircraft,especially the directional damping characteristics,and decouple the longitudinal responses from the drag rudders.

Stability characteristics and airworthiness requirements of blended wing body aircraft with podded engines

Blended-Wing-Body(BWB)aircraft have a relatively short fuselage and no horizontal tail,and they usually adopt podded engines and a V tail instead of a vertical tail.Generally,BWB aircraft have decreased longitudinal and directional static stability and damping.In this paper,the three-axis static and dynamic stability characteristics of an example BWB aircraft with podded engines are studied.According to the differences in flight characteristics of BWB aircraft and conventional aircraft,the different airworthiness requirements for BWB aircraft are analyzed:first,based on current airworthiness regulations and transport aircraft flying quality specification,the relaxation requirement of longitudinal static stability for BWB aircraft is studied;second,the influences of podded engines on longitudinal trim,attitude and trajectory responses and maximum directional control power requirement of BWB aircraft are analyzed;third,the changes in the proportional relationships between the takeoff characteristic speeds of the example BWB aircraft are analyzed.In view of these variations in directional control power requirement and relationships between takeoff characteristic speeds,new recommendations for airworthiness evaluation are proposed for BWB aircraft.The conclusions of this paper are helpful references for configuration design,flight control law design and airworthiness evaluation of BWB aircraft.