Quantitative Identification of Delamination Damage in Composite Structure Based on Distributed Optical Fiber Sensors and Model Updating

Delamination is a prevalent type of damage in composite laminate structures.Its accumulation degrades structural performance and threatens the safety and integrity of aircraft.This study presents a method for the quantitative identification of delamination identification in composite materials,leveraging distributed optical fiber sensors and a model updating approach.Initially,a numerical analysis is performed to establish a parameterized finite element model of the composite plate.Then,this model subsequently generates a database of strain responses corresponding to damage of varying sizes and locations.The radial basis function neural network surrogate model is then constructed based on the numerical simulation results and strain responses captured from the distributed fiber optic sensors.Finally,a multi-island genetic algorithm is employed for global optimization to identify the size and location of the damage.The efficacy of the proposed method is validated through numerical examples and experiment studies,examining the correlations between damage location,damage size,and strain responses.The findings confirm that the model updating technique,in conjunction with distributed fiber optic sensors,can precisely identify delamination in composite structures.

Crystal Structure and Chemical Composition of Ludwigite from Vranovac Ore Deposit (Boranja Mountain,Serbia)

The crystal structure of ludwigite from Vranovac ore deposit （Boranja Mt., Serbia） was refined using the X-ray powder diffraction （XRPD） Rietveld method in the space group Pbam to a final RB=7.45% and RF=5.26%. It has the unit cell dimensions of： a=9.2515（2） A; b=12.3109（2） A; c=3.03712 （7） A; and V=345.91（1） A3. The calculated distances and angles are mostly in good agreement with the Mg2＋-Fe2＋ substitutions across the M（1） and M（3） sites, as well as with the Fe3＋-AI3＋ replacement in the M（4） site. However, the mean observed M（2）-O distance is considerably shorter than prescribed, due to a slight increase of the Fe3＋ content in the M（2） site. Such replacement was compensated by slight increase of the Fe2＋ content in the M（4） site, resulting in the （Mg1.4sFe2＋o.46Fe3＋o.osMno.o2）2.o1 （Fe3＋o.94Fe2＋0.04Al0.02）1.00B1.00Os composition. The formation temperature was estimated to be about 500- 600C. The influences of the various chemical compositions to the crystallographic parameters, M-O distances, M（3） and M（4） sites shift, distortion parameters and estimated valences, were also studied and compared with other reference samples.

Functionally graded structure of a nitride-strengthened Mg_(2)Si-based hybrid composite

The ex-situ incorporation of the secondary SiC reinforcement,along with the in-situ incorporation of the tertiary and quaternary Mg_(3)N_(2) and Si_(3)N_(4) phases,in the primary matrix of Mg_(2)Si is employed in order to provide ultimate wear resistance based on the laser-irradiation-induced inclusion of N_(2) gas during laser powder bed fusion.This is substantialized based on both the thermal diffusion-and chemical reactionbased metallurgy of the Mg_(2)Si–SiC/nitride hybrid composite.This study also proposes a functional platform for systematically modulating a functionally graded structure and modeling build-direction-dependent architectonics during additive manufacturing.This strategy enables the development of a compositional gradient from the center to the edge of each melt pool of the Mg_(2)Si–SiC/nitride hybrid composite.Consequently,the coefficient of friction of the hybrid composite exhibits a 309.3%decrease to–1.67 compared to–0.54 for the conventional nonreinforced Mg_(2)Si structure,while the tensile strength exhibits a 171.3%increase to 831.5 MPa compared to 485.3 MPa for the conventional structure.This outstanding mechanical behavior is due to the(1)the complementary and synergistic reinforcement effects of the SiC and nitride compounds,each of which possesses an intrinsically high hardness,and(2)the strong adhesion of these compounds to the Mg_(2)Si matrix despite their small sizes and low concentrations.

Separation, Purification and Identification of Antioxidant Compositions in Black Rice

To separate, purify and identify the antioxidative compositions of black rice, using total antioxidation capacity （TAC） as an activity-monitoring parameter, different fractions of black rice antioxidative extracts were obtained using solvents of different polarities such as petroleum ether, chloroform, ethyl acetate and normal butyl alcohol. The main anfioxidative components were separated from the strongest antioxidative fractions by using Sephadex LH-20 resin and the structures were analyzed by ultraviolet-vis, infra-red, ESI-MS, ^1H-NMR and ^13C-NMR spectrums. Results showed that the water fraction and normal butyl alcohol antioxidafive extract fraction of black rice had the strongest antioxidation capacities and their TACs reached 383 and 392 ku g^-1, respectively. Four main antioxidative components were separated from the water fraction and their TACs reached 976, 878, 1 134 and 1087 ku g^-, respectively. The spectroscopy analysis indicated that the four active components of the antioxidative extract of black rice were four anthocyanin compounds of malvidin, pelargonidin- 3, 5-diglucoside, cyaniding-3-glucoside and cyaniding-3, 5-diglucoside. It is concluded that the anthocyanin compounds are the most important substantial foundations for antioxidation.

Chemical Compositions of Stemmacantha carthamoides Root

[Objectives] Chemical compositions of S. carthamoides root were isolated and identified. [Methods]Solvent extraction,repeated silica gel column chromatography,ODS column chromatography,preparative liquid chromatography and recrystallization were used for separation and purification,and chemical structure of compound was identified via its physical-chemical properties and spectral analysis data.[Results] Eight compounds were obtained from methanol extract of S. carthamoides root: 24-ethyl-20-oxhydryl ecdysone( 1),β-ecdysterone( 2),Ajugasterone C( 3),3,4-DHBA( 4),3-methoxy-quercetin( 5),( 7 S,8 S)-syringoylglycerol( 6),( E)-3,7-dimethyl-1-O-[α-L-arabinofuranosyl-( 1→6)-β-D-glucopyranosy1]-oct-2-en-7-ol( 7),Polypodine B( 8). [Conclusions] Compounds 6 and 7 were firstly isolated from the plant.

A Numerical Study of Densification Behavior of Silicon Carbide Matrix Composites in Isothermal Chemical Vapor Infiltration

We studied the characteristics of two-scale pore structure of preform in the deposition process and the mass transfer of reactant gas in dual-scale pores, and observed the physiochemical phenomenon associated with the reaction. Thereby, we established mathematical models on two scales, respectively, preform and reactor. These models were used for the numerical simulation of the process of ceramic matrix composites densified by isothermal chemical vapor infiltration(ICVI). The models were used to carry out a systematic study on the influence of process conditions and the preform structure on the densification behaviors. The most important findings of our study are that the processing time could be reduced by about 50% without compromising the quality of the material, if the processing temperature is 950-1 000 ℃ for the first 70 hours and then raised to 1 100 ℃.

A Review of Structural Health Monitoring Techniques as Applied to Composite Structures

Structural Health Monitoring(SHM)is the process of collecting,interpreting and analysing data from structures in order to determine its health status and the remaining life span.Composite materials have been extensively use in recent years in several industries with the aim at reducing the total weight of structures while improving their mechanical properties.However,composite materials are prone to develop damage when subjected to low to medium impacts(i.e.1-10 m/s and 11-30 m/s respectively).Hence,the need to use SHM techniques to detect damage at the incipient initiation in composite materials is of high importance.Despite the availability of several SHM methods for the damage identification in composite structures,no single technique has proven suitable for all circumstances.It must be noted that the amount of techniques available nowadays is too extensive to be comprehensively reviewed in a single paper.Therefore,the focus will be on techniques that can serve as a starting point for studies focusing on damage detection,localisation,assessment and prognosis on certain kinds of structures.Thus,the line of thought behind the search and the structure of this review is a result of objectives beyond the scope of the paper itself.Nevertheless,it was considered that,once the above was understood,an updated synopsis such as this could also be useful for other researchers in the same field.

Compositional and Structural Study of Macerals in Coals and Source Rocks Using SIMS

The authors applied the Secondary Ion Mass Spectrometry (SIMS) technique to the analysis of compositions and structures of vitrinites fusinites, fusinites bitumens and graptolites in the hydrocarbon source rocks with different maturities dscribed their SIMS spectral characteristics and found that different macerals have differnt spectra which, reflected the compositional and structural differences of macerals. Moreover, the change bod of parameter CH2+/CH3+ can be used for the evaluation of thermal evolution regularity of macerals in the hydrocarbon source rocks The study results show that the SIMS technique is a powerful means for microara analysis of macerals in coals and source rocks. It is certain that the study level of macerals can be raised by detailed study of SIMS results of SIMS results of macerals.

Microstructure of TA2/TA15 graded structural material by laser additive manufacturing process

TA2/TA15 graded structural material（GSM） was fabricated by the laser additive manufacturing（LAM） process. The chemical composition, microstructure and micro-hardness of the as-deposited GSM were investigated. The results show that the TA2 part of exhibiting near-equiaxed grains was Widmanst？tten α-laths microstructure. The TA15 part containing large columnar grains was fine basket-weave microstructure. The graded zone was divided into four deposited layers with 3000 μm in thickness. As the distance from the TA2 part increases, the alloy element contents and the β phase volume fraction increase, the α phase volume fraction decreases and the microstructure shows the evolution from Widmanst？tten α-laths to basket-weave α-laths gradually. The micro-hardness increases from the TA2 part to the TA15 part due to the solid solution strengthening and grain boundary strengthening.

Investigation on Chemical Components of Higher Fungus Phellinus rhabarbarinus(Berk.) G. Cunn.

Five compounds including 2 benzene derivatives, 2 terpenoids and 1 sterol were separated by various separation methods such as positive silica gel, Sephadex LH-20 and Rp-18 gel from higher fungi Phellinus rhabarbarinus （Berk.） G. Cunn. Their structures were elucidated on the basis of nuclear magnetic resonance （NMR） spectroscopy and other methods. All the compounds were separated from this higher fungus for the first time.

Structures and characteristics of carbohydrates in diets fed to pigs: a review

The current paper reviews the content and variation of fiber fractions in feed ingredients commonly used in swine diets.Carbohydrates serve as the main source of energy in diets fed to pigs.Carbohydrates may be classified according to their degree of polymerization: monosaccharides,disaccharides,oligosaccharides,and polysaccharides.Digestible carbohydrates include sugars,digestible starch,and glycogen that may be digested by enzymes secreted in the gastrointestinal tract of the pig.Non-digestible carbohydrates,also known as fiber,may be fermented by microbial populations along the gastrointestinal tract to synthesize short-chain fatty acids that may be absorbed and metabolized by the pig.These non-digestible carbohydrates include two disaccharides,oligosaccharides,resistant starch,and non-starch polysaccharides.The concentration and structure of non-digestible carbohydrates in diets fed to pigs depend on the type of feed ingredients that are included in the mixed diet.Cellulose,arabinoxylans,and mixed linked β-(1,3)(1,4)-D-glucans are the main cell wall polysaccharides in cereal grains,but vary in proportion and structure depending on the grain and tissue within the grain.Cell walls of oilseeds,oilseed meals,and pulse crops contain cellulose,pectic polysaccharides,lignin,and xyloglucans.Pulse crops and legumes also contain significant quantities of galacto-oligosaccharides including raffinose,stachyose,and verbascose.Overall,understanding the structure,characteristics and measurable chemical properties of fiber in feed ingredients may result in more accurate diet formulations,resulting in an improvement in the utilization of energy from less expensive high-fiber ingredients and a reduction in reliance on energy from more costly cereal grains.

Critical pharmaceutical process identification considering chemical composition, biological activity, and batch-to-batch consistency: A case study of notoginseng total saponins

Objective: Critical pharmaceutical process identification(CPPI) is an important step in the implementation of quality by design concept to traditional Chinese medicines(TCMs). Risk assessment methods are usually used in CPPI. However, risk evaluation is usually subjective. The purpose of this work is to present a more objective CPPI method.Methods: A CPPI method considering chemical composition, biological activity, and batch-to-batch consistency was presented in this work. The manufacturing process of notoginseng total saponins(NTS) was investigated as an example. The changes of chemical composition, biological activity, and chemical composition consistency after main processes were measured and compared. A significant change of them indicated a critical process.Results: After extraction process and chromatography process, saponin purity and chemical composition similarity remarkably increased, and saponin content variations decreased. Thrombin inhibitory activity was remarkably decreased after chromatography process. Because of the large influences on NTS quality,extraction process and chromatography process were identified to be critical processes of NTS.Conclusion: Based on a comprehensive and objective examination of the role of each process, critical pharmaceutical processes can be identified. A similar method can also be applied to other TCM processes.

The chemical constituents of the tissue culture cells of Daphne giraldii cullus

Three compounds were isolated from the tissue culture cells of Daphne giraldii cullus, their structures were identified as daphneolone （1）, S-（＋）-1-（4-hydroxy-3-methoxyphenyl）-3-hydroxy-5-phenyl-l-pentanone （2）, S-（＋）-1-（4-methoxyphenyl）-3- hydroxy-5-phenyl-l-pentanone （3）, and among them, 2 was a new compound, 3 was a novel natural product.

Study on Chemical Constituents of Ethanol Extract from Yao Medicine Cissampelopsis spelaeicola

[Objectives]The research aimed to study the chemical constituents of ethanol extract from Yao medicine Cissampelopsis spelaeicola.[Methods]The petroleum ether,ethyl acetate and n-butanol fractions from 75%ethanol extract of C.spelaeicola were isolated and purified by silica gel,SephadexLH-20 gel column and AB-8 macroporous resin column,etc.The structures of the compounds were analyzed and identified by physicochemical properties and spectral data(mass spectrometry,hydrogen spectrum and carbon spectrum).[Results]Twelve compounds were isolated and identified from 75%ethanol extract of C.spelaeicola.β-sitostero(I)and stigmasterol(II)were isolated from petroleum ether fraction;p-hydroxybenzoic acid(III),β-daucossterol(IV),protocatechuic acid(V),6β-hydroxyeremophi-7(11)-en-12,8β-olide(VI),10β-hydroxyeremophil-7(11)-en-8,12-olide(VII),10β-hydroxyeremophi-7(11),8(9)-dien-8,12-olide(VIII),quercetin(IX),hyperin(X)and 4α-hydroxy-eudesman-11-ene(XI)were isolated from ethyl acetate fraction;quercetin-3-O-robinobioside(XII)was isolated from n-butanol fraction.Compounds I-XII were isolated from C.spelaeicola for the first time.[Conclusions]The study can lay material foundation for activity study of C.spelaeicola.

Chemical Constituents from Ethnic Medicine Laportea bulbifera

[Objectives]This study was conducted to study the chemical constituents from Laportea bulbifera. [Methods] The 60% ethanol extract from L. bulbifera was isolated and purified by silica, Sephadex LH-20, ODS, semi-preparative HPLC and recrystallization. Their chemical structures were elucidated by physicochemical properties and spectroscopic methods. [Results] These compounds were determined as kaempferol-3-O-α-L-(3-O-acetyl)-rhamnoside-7-O-α-L-rhamnoside(1), sutchuenoside A(2), kaempferol-3-O-[β-D-glucopyranosyl-(1→3)]-α-L-(4-O-acetyl)-rhamnopyranoside-7-O-α-L-rhamnopyranoside(3). Compounds 1-3 are isolated from genus Laportea for the first time. Compound 3 is a new compound. [Conclusions] This study lays a foundation for improving the quality standard of L. bulbifera and the development and utilization of its resources.

Study on the Chemical Constituents of Clerodendrum japonicum,a Zhuang Medicine

[Objectives]To make a preliminary study on the chemical constituents of Clerodendrum japonicum,a Zhuang medicine,so as to provide theoretical support and scientific basis for exploring its medicinal value and comprehensive development and utilization.[Methods]The compounds were separated by macroporous adsorption resin,silica gel,Sephadex LH-20,ODS chromatographic column and preparative high performance liquid chromatography,and their structures were identified by NMR and MS data.[Results]8 compounds were isolated and identified from Clerodendrum japonicum extract with 80%ethanol solution:(1)fumaric acid,(2)trans-p-hydroxycinnamic acid,(3)cis-p-hydroxycinnamic acid,(4)ethyl caffeate,(5)acteoside,(6)kaempferol,(7)apigenin-7-O-β-D-glucopyranoside,(8)caffeic acid.[Conclusions]8 compounds were isolated and purified from the ethanol extract of Clerodendrum japonicum.

Study on Chemical Constituents from Phellodendron chinense

[Objectives]To isolate and identify chemical constituents from Phellodendron chinense.[Methods]Compounds were isolated by silica gel,Sephadex LH-20,and ODS column chromatography,and their structures were determined by means of the spectral analysis and physicochemical properties.[Results]Eleven compounds were isolated and identified as berberine(1),obaculactone(2),shihulimonin A(3),N-p-coumaroyltyramine(4),1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-hydroxy-propyl)-2-methoxyphenoxy]-propane-1,3-diol(5),phellodendrine(6),magnoflorine(7),palmatine(8),jatrorrhizine(9),columbamine(10),and obacunone(11).[Conclusions]Compounds 3 and 5 were isolated from Phellodendron for the first time,and compound 4 was isolated from this plant for the first time.

低分子质量岩藻聚糖硫酸酯的分离纯化、结构表征及体外抗氧化活性

以裙带菜岩藻聚糖硫酸酯为原料,采用自由基氧化降解法及强阴离子交换色谱技术,制备纯化得到低分子质量岩藻聚糖硫酸酯F-1和F-2。通过分子排阻色谱、高效液相色谱、红外光谱和核磁共振技术对F-1和F-2的化学组成和结构特征进行解析,探究低分子质量岩藻聚糖硫酸酯的抗氧化构效关系。结果表明:F-1和F-2主要由岩藻糖和半乳糖组成,分子质量分别为2790 Da和23510 Da,硫酸基质量分数分别为(27.05±0.95)%和(34.73±0.08)%,糖醛酸质量分数分别为(15.39±0.33)%和(6.76±0.38)%。F-1和F-2的糖苷键构型均为α型,且具有一定程度的乙酰化和硫酸化。综合比较不同质量浓度F-1和F-2的体外抗氧化活性,发现二者均可清除1,1-二苯基-2-三硝基苯肼自由基和2,2’-联氮-二(3-乙基苯并噻唑-6-磺酸)阳离子自由基,对铁氰化钾具有一定的还原能力,并呈现剂量依赖性。分子质量较小的F-1糖链上的糖醛酸、半乳糖含量相对较高,在相同剂量条件下其抗氧化活性优于F-2。该研究结果可为将低分子质量岩藻聚糖硫酸酯作为一种优良的天然抗氧化物质应用于保健食品和化妆品等领域提供理论依据。

One-pot synthesis of Sb-Fe-carbon-fiber composites with in situ catalytic growth of carbon fibers

A Sb-Fe-carbon-fiber （CF） composite was prepared by a chemical vapor deposition （CVD） method with in situ growth of CFs us- ing Sb203/Fe2O3 as the precursor and acetylene （C2H2） as the carbon source. The Sb-Fe-CF composite was characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM） and transmission electron microscopy （TEM）, and its electrochemical per- formance was investigated by galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy. The Sb-Fe-CF composite shows a better cycling stability than the Sb-amorphous-carbon composite prepared by the same CVD method but using Sb2O3 as the precur- sor. Improvements in cycling stability of the Sb-Fe-CF composite can be attributed to the formation of three-dimensional network structure by CFs, which can connect Sb particles firmly. In addition, the CF layer can buffer the volume change effectively.

关苍术亲脂性化学成分研究

目的:研究关苍术亲脂性成分的化学成分。方法:使用硅胶柱色谱、Sephadex LH-20柱色谱、中压液相色谱和半制备HPLC等方法对关苍术中的化学成分进行分离纯化,并通过理化性质和MS与NMR等波谱技术对其化学成分进行结构鉴定。结果:从关苍术药材中分离并鉴定了12种化合物,分别鉴定为osthol(1)、Atractylochromene(2)、6,7-二羟基-8-甲氧基香豆素(3)、8-羟基-6,7-二甲氧基香豆素(4)、7-甲氧基香豆素(5)、豆甾-4-烯-3-酮(6)、蒲公英萜醇乙酸酯(7)、白术内酯Ⅱ(8)、白术内酯Ⅰ(9)、桉叶-4(15)-烯-7β,11-二醇(10)、反式对羟基桂皮酸甲酯(11)、丁香醛(12)。结论:化合物1,3~6,10~12为首次从关苍术中分离的化合物。