ANALYSIS OF CAPSAICIN AND DIHYDROCAPSAICIN IN HOT PEPPERS BY ULTRASOUND ASSISTED EXTRACTION FOLLOWED BY GAS CHROMATOGRAPHY–MASS SPECTROMETRY

A simple method for the analysis of capsaicin and dihydrocapsaicin in peppers by ultrasound assisted extraction (USAE) followed by gas chromatography–mass spectrometry (GC-MS) has been developed. USAE conditions were optimized by experimental design in order to maximize analyte extraction. A full factorial design involving extraction variables such as solvent (ethanol and water), extraction time (5–25 min), extraction temperature (25–50 °C), sample amount (0.25–0.5 g), and ultrasound amplitude (40–80%) was applied. The most significant conditions for capsaicinoid extraction by USAE were solvent type, extraction time, and sample amount. The obtained results were compared with other extraction methods: the official Soxhlet method and a previously reported solid phase microextraction method. Results showed that the extraction efficiency with the application of USAE (98%) was as good as that obtained with Soxhlet and the precision of recovery was less than 5%; in addition, the extraction time was decreased from 5 h to 25 min. The GC-MS analytical method was linear in the range 10–100 μg/mL for capsaicin and dihydrocpsaicin with correlation coefficient r = 0.998 and peak area variability of ～1% for both capsaicinoids. The method was applied to the analysis of 11 varieties of hot peppers cultivated in México. A large concentration range for capsaicin (101–6800 μg/g) and dihydrocapsaicin (110–2736 μg/g) was found in these pepper samples.     

A FAST,HIGH SENSITIVITY AND HIGH MASS ACCURACY API TIME-OF-FLIGHT MASS SPECTROMETER AND ITS APPLICATIONS

Greatdemandarenowbeingplaceonliquidsampledetectorsduetonewemergingfastseparationtechnology,highnumberofsamplenowneededtobeanalyzed,andThehighaccuracyforconformation.ExamplesincludeMicroboreHPLC,capillaryelectrophoresisandoTherfastseparationtechniquesWhicheludePeakswithfullwidthhalfmaximumsofasecondorless.Also,analyticalgroupsinthepharmaceuticalindustrymustcharacterizealargenumberofsamples,placingapremiumonhighthroughput.Particularly,Theuseofcombinatorialchemistryindrugdiscoveryhasproducedt…     

CRITICAL REVIEW ON THE ANALYTICAL METHODS FOR THE DETERMINATION OF ZWITTERIONIC ANTIEPILEPTIC DRUGS—VIGABATRIN,PREGABALIN, AND GABAPENTIN—IN BULK AND FORMULATIONS

Drugs with antiepileptic activity constitute a group of heterogeneous compounds and therefore their determination cannot follow a universal procedure. Among them, vigabatrin, pregabalin, and gabapentin are of similar nature, due to their zwitterionic structure. This structure enables similar approaches for their determination, including derivatization protocols. This article presents a thorough survey on published methods for the determination of this subgroup of antiepileptic compounds in bulk and pharmaceutical preparations. Spectrophotometric and spectrofluorimetric methods, with or without derivatization reagents, as thin-layer chromatography, high-performance liquid chromatography with various detectors, gas chromatography, capillary electrophoresis, infrared, and potentiometric methods, have been extensively applied for these compounds, providing reliable results. Additionally, the number of citations and purpose for each method were discussed with critical commentary.     

IDENTIFICATION AND INVESTIGATION OF ELEMENT SULFUR IN COAL BY MEANS OF GC/MS, CIMS/MS AND SIMS

Ingeneralcoalcontainsthreesortsofchemicalformsofsulfur,includinginorganicsulfides,inorganicsulfatesandorganic-sulfurcompounds.However,therecentobservationssuggestthatelementsulfur,ormono-sulfur,probablyexistsinsomecoalseiTher[1,2].Forthepurposeofacontinuousapproachoftheelementsulfur,heredifferenttechniquesoforganicmassspectrometryarecoordinatedtocharacterizethehigh-sulfurcoalscollectedfromthesouthwestofChina.Thecoalscollectedfromfourdifferentsitesarepreparedwithdifferentphysicaltreatmentsandt…     

CRACK PROPAGATION BEHAVIOR AND LIFETIME PREDICTION IN ALUMINA AND ZIRCONIA

The lifetime prediction of ceramics is discussed on the basis of the relationship between stress intensity factorK1 and crack velocity ν. The effects of water environment, the cyclic loading and microstructure of material on K1-ν characteristics are studied by carrying out the crack growth tests by the double torsion (DT) method under the static andcyclic loading in both environments of air and water for alumina and zirconia. K1-ν characteristics determined by the double torsion method are used to predict time-to-failure under the cyclic loading of alumina and zirconia ceramics. The predictions agree qualitatively with the experimental results.     

INDUCTION-HEATED TOOL MACHINING OF ELASTOMERS—PART 2: CHIP MORPHOLOGY,CUTTING FORCES,AND MACHINED SURFACES

ABSTRACT

The induction-heated tool and cryogenically cooled workpiece are investigated for end milling of elastomers to generate desirable shape and surface roughness. Elastomer end milling experiments are conducted to study effects of the cutting speed, tool heating, and workpiece cooling on the chip formation, cutting forces, groove width, and surface roughness. At high cutting speed, smoke is generated and becomes an environmental hazard. At low cutting speeds, induction heated tool, if properly utilized, has demonstrated to be beneficial for the precision machining of elastomer with better surface roughness and dimensional control. Frequency analysis of cutting forces shows that the soft elastomer workpiece has low frequency vibration, which can be correlated to the surface machining marks. The width of end-milled grooves is only 68 to 78% of the tool diameter. The correlation between the machined groove width and cutting force reveals the importance of the workpiece compliance to precision machining of elastomer. This study also explores the use of both contact profilometer and non-contact confocal microscope to measure the roughness of machined elastomer surfaces. The comparison of measurement results shows the advantages and limitations of both measurement methods.     

LUBRICATION AND LOADED TOOTH CONTACT ANALYSIS FOR SPIRAL BEVEL AND HYPOID GEARS

ＬＵＢＲＩＣＡＴＩＯＮＡＮＤＬＯＡＤＥＤＴＯＯＴＨＣＯＮＴＡＣＴＡＮＡＬＹＳＩＳＦＯＲＳＰＩＲＡＬＢＥＶＥＬＡＮＤＨＹＰＯＩＤＧＥＡＲＳＬＵＢＲＩＣＡＴＩＯＮＡＮＤＬＯＡＤＥＤＴＯＯＴＨＣＯＮＴＡＣＴＡＮＡＬＹＳＩＳＦＯＲＳＰＩＲＡＬＢＥＶＥＬＡＮＤ...     

RESEARCH OF FATTY ACID IN HEPATIC TISSUE OF HEPATOCELLULAR CARCINOMA BY GAS CHROMATOGRAPHY/MASS SPECTROMETRY

FattyacidisoneofTheimportantcomponentsinhumanlivercell.Innormalcondition,itliescomparativelyinstablestate.Oncepatientssufferfromlivercancer,thebalancewillbebro-ken,thenthesortandamountoffattyacidwillbechanged.Atpresenttime,analysisandassessmentforhistocytedependsonthetraditionalmorphologicalmethod,usingopticalmicroscopeandelectronicmicroscopeasThemainway.Recentyearsmolecularpathologyisboominggradually.themethodofanalyzingcellconstituentonmolecularlevelhasdevelopedmorequicklythaneverbefore,esp…     

LEVEL SET METHOD FOR TOPOLOGICAL OPTIMIZATION APPLYING TO STRUCTURE, MECHANISM AND MATERIAL DESIGNS

Based on a level set model, a topology optimization method has been suggested recently. Ituses a level set to express the moving structural boundary which can flexibly handle complex topo-logical changes. By combining vector level set models with gradient projection technology, the levelset method for topological optimization is extended to a topological optimization problem withmulti-constraints, multi-materials and multi-load cases. Meanwhile, an appropriate nonlinear speedmapping is established in the tangential space of the active constraints for a fast convergence. Then themethod is applied to structure designs, mechanism and material designs by a number of benchmarkexamples. Finally, in order to further improve computational efficiency and overcome the difficultythat the level set method cannot generate new material interfaces during the optimization process, thetopological derivative analysis is incorporated into the level set method for topological optimization,and a topological derivative and l     

ARTIFICIAL NEURAL NETWORK AND FUZZY LOGIC CONTROLLER FOR GTAW MODELING AND CONTROL

0 INTRODUCTION(The satisfied control of the overall weld process is not easily accomplished, largely due to the inadequacies of the available process models. Without exceptions, most welding control methods are based upon the analytical welding models. Although these models are derived directly from the physical laws that govern the main features of the weld pool, a number of assumptions are made to obtain the mathematical solutions and some variables are ignored due to the complexity of t…     

FORCE TRANSDUCER MODELING OF RECTANGULAR,V–SHAPED,AND DAGGER CANTILEVER PROBES BASED ON ATOMIC FORCE MICROSCOPY

Real-time monitoring of the nano-particle manipulation process by atomic force microscope (AFM) is almost impossible since the manipulator of the AFM is used as either the imaging or manipulation tool at a given instant. As one approach to this problem, researchers scan the area where the target particle exists, before and after the nano-manipulation. Thus, by using some fixed reference features, the new relative position of the particle is obtained from the images. However, this imaging is offline, and unexpected problems during nano-manipulation process cannot be detected. In this article, force transducer of the AFM rectangular, V-shaped, and dagger cantilevers, which convert the three-dimensional deflections measured by the detection system to corresponding three-dimensional force, are modeled and compared. So there would be a feedback from the real-time force system during nano-manipulation process, which can be utilized for better understanding and reliable handling of nano-particles. Furthermore, the manipulation forces are affected directly by spring constants of cantilever. Hence, the cantilever is the most significant and sensitive component of the AFM. Therefore, variations of the lateral, longitudinal, and normal spring constants of the mentioned cantilever for different geometrical parameters are analyzed and discussed.     

MODELING AND IMPLEMENTATION OF A DISTRIBUTED SHOP FLOOR MANAGEMENT AND CONTROL SYSTEM

Adopting distributed control architecture is the important development direction for shop floor management and control system, is also the requirement of making it agile, intelligent and concurrent. Some key problems in achieving distributed control architecture are researched. An activity model of shop floor is presented as the requirement definition of the prototype system. The multi-agent based software architecture is constructed. How the core part in shop floor management and control system, production plan and scheduling is achieved. The cooperation of different agents is illustrated. Finally, the implementation of the prototype system is narrated.     

MODELING AND PERFORMANCE ANALYSIS FOR THE SERIAL AND PARALLEL PRODUCTION SYSTEM BASED ON GSPN

Differed from the existed applications of generalized stochastic Petri net (GSPN) theory in machine-tool manufacturing system, reliability computation of FMS, testability parameters determination and fault analysis, a new idea of applying GSPN to model and performance analysis for the serial and parallel production system is proposed. And one typical discrete event dynamic system (DEDS), turner-unit of palletizing system, is taken as a real case to research. Based upon the established GSPN models, the working performances of serial and parallel layout are compared. Furthermore, their differences of working mechanisms including feeding mechanism, coordinating mechanism and monitoring mechanism are discussed. Thus the theoretical basis which is helpful to appraise layout plan and its reasonableness is provided. Meanwhile, the research results show that parallel layout is more advantageous to greatly improve the operational speed of production system than serial one.     

FUZZY ECCENTRICITY AND GROSS ERROR IDENTIFICATION

The dominant and recessive effect made by exceptional interferer is analyzed in measurement system based on responsive character, and the gross error model of fuzzy clustering based on fuzzy relation and fazzy equipollence relation is built. The concept and calculate formula of fuzzy eccentricity are defined to deduce the evaluation rule and function of gross error, on the base of them, a fuzzy clustering method of separating and discriminating the gross error is found. Utilized in the dynamic circular division measurement system, the method can identify and eliminate gross error in measured data, and reduce measured data dispersity. Experimental results indicate that the use of the method and model enables repetitive precision of the system to improve 80% higher than the foregoing system, to reach 3.5s, and angle measurement error is less than 7 s.     

COMPUTER PAN-VISION THEORY AND IT''''S BACKGROUND

０ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＭａｒ’ｓｃａｌｃｕｌａｔｉｏｎｔｈｅｏｒｙｉｓｔｈｅｍａｉｎｓｔｒｅａｍｏｆｃｏｍｐｕｔｅｒｖｉｓｉｏｎ（ＣＶ），ａｎｄｈａｓａｃｑｕｉｒｅｄａｇｒｅａｄａｃｈｉｅｖｅｍｅｎｔ．Ｂｕｔｔｈｅｒｅａｒｅｓｅｒｉｏｕｓｄ...     

专利与信息PATENTS AND NEWS

专利与信息ＰＡＴＥＮＴＳＡＮＤＮＥＷＳ编者按本栏目是中国专利局文献部分类文档处与赤刊合作共办的。目的是适应改革开放形势的需要，为本刊读者及时利用专利文献提供方便，以推动科技进步。由中国专利局批准并注册的天津市机械工业管理局专利事务所与本刊联合竭诚为您...     

DESIGN AND EXPERIMENT OF ELECTRIC BUS

0 INTRODUCTION*Human being has waked up to come to face with more and more serious environmental pollution and energy crisis，decrease of emission and fuel consumption of automobile have been paid special attention. Electric vehicles have become focus because they have the advantages of vehicles using internal combustion engines in terms of zero emission，usage of alternative energy source and lower noise. More and more countries including China convoked their researchers and invested cap…     

FAULT DIAGNOSIS BASED ON INTEGRATION OF CLUSTER ANALYSIS, ROUGH SET METHOD AND FUZZY NEURAL NETWORK

In order to increase the efficiency and decrease the cost of machinery diagnosis, a hybrid system of computational intelligence methods is presented. Firstly, the continuous attributes in diagnosis decision system are discretized with the self-organizing map (SOM) neural network. Then, dynamic reducts are computed based on rough set method, and the key conditions for diagnosis are found according to the maximum cluster ratio. Lastly, according to the optimal reduct, the adaptive neuro-fuzzy inference system (ANFIS) is designed for fault identification. The diagnosis of a diesel verifies the feasibility of engineering applications.     

DISTANCE MEASURING MODELING AND ERROR ANALYSIS OF DUALCCD VISION SYSTEM SIMULATING HUMAN EYES AND NECK

A dual-CCD simulating human eyes and neck (DSHEN) vision system is put forward. Itsstructure and principle are introduced. The DSHEN vision system can perform some movementssimulating human eyes and neck by means of four rotating joints, and realize precise object recogniz-ing and distance measuring in all orientations. The mathematic model of the DSHEN vision system isbuilt,and its movement equation is solved. The coordinate error and measure precision affected by themovement parameters are analyzed by means of intersection measuring method. So a theoretic founda-tion for further research on automatic object recognizing and precise target tracking is provided.