Search

PurposeThe purpose of this paper is to analyze the optimal competition or cooperation decision between technology service platforms and governments in the context of fierce competition within urban agglomerations.Design/methodology/approachBased on the cooperation and competition game model, this study builds a two-level model for government and technology service platforms considering three cases: perfect competition, platform cooperation and government-led cooperation.FindingsBy analyzing the optimal strategies of the government and a platform in three cases, the research shows that choosing appropriate cooperation in a competitive situation is beneficial to both the government and the platform. Government-led cooperation is conducive to increasing social welfare. From the perspective of the platforms, if they actively seek cooperation, they can obtain higher subsidies and profits. The more intense the competition is, the higher the profits and social welfare generated from the platforms' active cooperation.Practical implicationsThe contribution of this study relates to the development of technology service platforms in urban agglomerations. As local governments and platforms continuously undertake decision-making processes, this study constructs quantitative models to analyze the advantages and disadvantages of competition and cooperation. It is worth noting that relying on government subsidies to maintain the sustainable development of technology service platforms is not a long-term solution. Government subsidies play a vital role in the initial development of technology service platforms. The analysis results are in line with Guo et al. (2016), Jung and Feng (2020) and Li (2021) conclusions. Furthermore, long-term government subsidies will make platforms dependent on these subsidies. These are the contributions to the scientific literature.Originality/valueInstead of focusing on vertical relationships, this study emphasizes the horizontal cooperation and competition relationship between platforms and local governments in an urban agglomeration. Thus, the vertical effects of government subsidies on platforms can be investigated. Another innovation is the social welfare policy goal, which is an important index for the development of urban agglomerations.

In the natural evolution, animals and plants have evolved many unique structures and properties. For example, butterfly wings appear to be colorful due to grating structures. Lotus leaves have super-hydrophobic property because of micro/ nano-structures. Nepenthes pitcher plants show slippery wettability by reason of the lubricant infused surfaces. Therefore, more and more researchers are trying to prepare unique structures which are similar to the surface of biological templates by different methods. Taking superhydrophobic surfaces as an example, there are many methods having been adopted to achieve superhydrophobic surfaces, such as etching, template method, UV lithography, electrostatic spinning, and nano-imprint technique. In recent years, laser processing technique has the advantages of high precision and arbitrary design, which shows great advantages in bionic manufacturing. For example, various kinds of micro/nano composites or structures have been successfully prepared by laser direct writing, two/four-beam interference, etc. However, these methods rely mainly on complex or sophisticated instruments, which take long time to prepare large-area superhydrophobic surfaces. Reed leaves show anisotropic superhydrophilicity property because of grating structures, which has applications in droplet transmission without loss and directional collection. Herein, we demonstrated the fabrication of bionic reed leaf by laser treatment of structured polydimethylsiloxane (PDMS) surface. Laser treatment of PDMS with micro-grating structures can induce the micro-nano structures and improve the surface roughness. To investigate the change of surface chemical composition, we carried out X-ray photoelectron spectroscopy (XPS) of PDMS before and after the laser treatment. After the laser treatment, the carbon content was decreased from 43.6% to 33.1%. The decrease in carbon content indicates the emission of carbon material during laser treatment, which is caused by the carbonization of the methyl group on the surface of the PDMS. At the same time, the oxygen content increased from 27.8% to 33.6% and the silicon content increased from 28.3% to 33.3%. To compare the surface morphologies changes of PDMS before and after laser treatment, we observed the surface morphology by confocal laser scanning microscopy (CLSM) and scanning electron microscope (SEM). The initial PDMS grating is about 100 μm wide, ~130 μm high and the structure surface is smooth. After laser treatment, it changes to about 200 μm wide, ~110 μm high and becomes much rougher surface. The variation in the width and height is mainly because that the laser treatment causes PDMS surface material to carbonize into rough structures. In order to evaluate the wettability changes of samples, the static water contact angle and dynamic water sliding angle measurement was carried out on the flat PDMS, the structured PDMS, and the laser-treated structured PDMS, respectively. The contact angle along the parallel direction was ∼155°, which is larger than that along the vertical direction (~150°). The sliding angle along the parallel direction was approximately 3°, which was smaller than the SA along the vertical direction (12°). This method provides a new idea for preparation of superhydrophobic surfaces with bionic structures by laser technology. The method is simple, convenient, and low cost, which may become a general method for preparing superhydrophobic surface.

Nitrogen-doped graphene or graphene derivatives have been proven superior electrode materials for high-performance supercapacitors. Synchronous N doping and reduction of graphene oxide (GO) is an effective approach to prepare such electrode materials. However, current strategies are limited to the use of liquid or vapor doping agents, making the preparation process complex and less environmentally friendly. We here report a facile way to prepare nitrogen-rich carbon nanoparticles (NCNPs), which can be employed as a solid-state doping agent for efficient N-doping of GO through direct laser writing photoreduction. The doping degree was tuned by varying the mass ratios of the NCNPs in the composites. After laser treatment, the composites show N concentration as high as 7.78 atom %. With the N-doped graphene composites as electrodes, the as-fabricated supercapacitors show high rate performance and obvious enhanced capacitance, revealing great potential for energy storage and conversion devices.

Shikonin, isolated from the roots of herbal plant Lithospermum erythrorhizon, is a naphthoquinone. It has been reported to exert beneficial anti-inflammatory effects and anti-oxidant properties in various diseases. Isoproterenol (ISO) has been widely used to establish cardiac injury in vivo and in vitro. However, shikonin function in ISO-induced cardiac injury remains uncertain. In our study, we attempted to investigate the efficiency and possible molecular mechanism of shikonin in cardiac injury treatment induced by ISO. In vivo, C57BL6 mice were subcutaneously injected with 5mg/kg ISO to induce heart failure. And mice were given a gavage of shikonin (2 or 4mg/kg/d, for four weeks). Cardiac function, fibrosis indices, inflammation response, apoptosis and endoplasmic reticulum (ER) stress were calculated. Pathological alterations, fibrosis-, inflammation-, apoptosis- and ER stress-related molecules were examined. In ISO-induced cardiac injury, shikonin significantly ameliorated heart function, decreased myocardial fibrosis, suppressed inflammation, attenuated apoptosis and ER stress through impeding collagen accumulation, Toll like receptor 4/nuclear transcription factor κB (TLR4/NF-κB), Caspase-3 and glucose-regulated protein 78 (GRP78) signaling pathways activity, relieving heart failure in vivo. Also, in vitro, shikonin attenuated ISO-induced cardiac muscle cells by reducing fibrosis, inflammation, apoptosis and ER stress. Our findings indicated that shikonin treatment attenuated ISO-induced heart injury, providing an effective therapeutic strategy for heart failure treatment for future.

Thirteen new analogues of diterpenoid alkaloids were synthesized from the potassium ion channel blocker talatisamine ( 1 ) by means of the ring-distortion strategy. Most of these derivatives are unique by featuring differentiated CD rings compared to the corresponding naturally-occurring alkaloids. Remarkable transformations including a novel rearrangement ( 1 → 7 and 13 → 7 ), an intriguing fragmentation ( 16 → 8 ), together with the preparation of an unprecedented C- homo - d -nor derivative 12 , were disclosed in this study.

Continuous investigations of the roots of Aconitum nagarum var. lasiandrum led to the isolation of two new C₁₉-diterpenoid alkaloids, lasiandrine (1) and lasiandroline (2). Their structures were elucidated on the basis of extensive interpretation of spectroscopic and mass spectrometric data.

Two new denudatine-type C20-diterpenoid alkaloids, named sinomontanidines A (1) and B (2), were isolated from the roots of Aconitum sinomontanum Nakai. Their structures were elucidated by extensive analysis of 1D, 2D NMR, and MS data.

Currently, SCR-DeNOx technology of flue gas has been widely applied in coal-fired power plants in China for its higher denitrification efficiency, lower ammonia escape and more stable operation performance. In order to overcome the shortages of the off-line method, an on-line method based activating was proposed. However, many key technologies also need to be researched that one of them is a cheap and efficient activating solution. First, activating solutions were prepared by means of single factor and experimental investigations of catalysts activation were conducted. Second, impacts of the catalysts, which were activated by the above mentioned solutions, NO removal and activity were tested and compared with that of the inactivated catalyst. The effect of active components (vanadium, tungsten, molybdenum, oxalic acid) and flue gas conditions on the activation of catalyst were investigated. Then, analysis of these catalysts by scanning electron microscopy (SEM), the specific surface area (BET), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were conducted. Finally, an ideal activating solution was found out through the analysis of the efficiency of denitrification and the macro and micro changes from catalysts. The following conclusions were obtained through the above mentioned activation experiments: 1) NO removal by activated catalysts is higher than that of inactivated catalyst; the De-NOx efficiency can be up to 99% in the following conditions: the reaction temperature (370 °C), the proportion of the active solution component (1.0%-V, 9%-W, 6%-Mo), the oxygen concentration (4%-O2) and the ratio of ammonia and nitrogen (NH3:N2 = 1:1); 2) the airspeed and the initial concentration of NO had little influence on catalyst activation; 3) the specific surface area and pore size of the activated catalyst were significantly increased that the active components of the catalyst surface were effectively added. Our investigation results to illustrate that the enhancement of active components, broadening of acid sites distribution, and including the surface labile oxygen and small pores opening to be the reason for high denitrification efficiency.

RPG (Role-playing Game) is one of the most common types of games in the game market, and Unity3D is a very popular engine. Usually, a RPG project development contains of the overall design, the description of mission system, the interface system design and the development of the game scene. The usage of NGUI plug-in to build UI (User Interface) has introduced in this paper. Based on that, the function of game is divided into menu, dialog box and knapsack. The design of mission system and the common methods of game role control have been analyzed in more detail. Through a series of test cases, it proved the game can be operated as expected.

Existing auto after-sales service recommendation only based on user' history behavior, and doesn't take user's real-time location into account, and the recommended result doesn’t meet user’s needs well. Aiming at the problem of traditional recommendation, put forward the personalized recommendation method based on LBS. This method takes the user as the core, by analyzing user's real-time behavior, historical behavior and the user's real-time geographic location, speculated the user's current needs, and recommend accurate information for them.

We have corrected (Tetrahedron 2013, 69, 5859–5866) the structures of diterpenoid alkaloids reported in the Journal of Natural Products 2012, 75, 1145–1159. Our follow-up experiments compel us to present further revisions and clarifications on the diterpenoid alkaloids: (1) The naturally occurring forms of carmichaelines B, C, and D in Shi's paper (Journal of Natural Products 2012, 75, 1145–1159) are neither quaternary ammonium hydroxides 2–4 nor the initially revised trifluoroacetates. They are indeed the vakognavine-type C20-diterpenoid alkaloids 11–13. (2) The samples' concentration is the critical factor to the signals' intensity for F3CCOO− in the alkaloid trifluoroacetates. Incorporation of TFA into the corresponding salts resulted in signals' enhancement due to the closeness of δ values (∼116 ppm, ∼159 ppm) of free TFA and those of F3CCOO−. After removal of free TFA, the carbon signals of CF3COO− could become weaker, but their chemical shifts remained almost unchanged. The possible reason might be the ionization of TFA in acetone. (3) The NMR data cannot distinguish TFA from trifluoroacetates (e.g., F3CCOONa and C19-diterpenoid alkaloid trifluoroacetates), indicating that the signal at around δ −76 cannot be used to exclude the existence of trifluoroacetates. In addition to the NMR and CSI-MS data, 1H–15N HMBC technique was also used to distinguish the free alkaloids from their trifluoroacetates. (4) The X-ray crystallographic analysis of compound 20 confirmed that the ‘new alkaloid’ (-b) in the Shi's paper is indeed the known compound aconifine trifluoroacetate. (5) Collectively, Shi's paper mixed-up the free alkaloids with their salts and the concepts of structure and conformation. Naming different structures with A-b and A-c is also confusing.

In the cloud computing federation, the method of cloud computing federation resource scheduling has been introduced to allocate the users requested tasks reasonably to the providers. In the present, single cloud providers method and system of resource scheduling dont apply to the cloud federation environment. Therefore, the solution to the problem of resource scheduling in cloud federation cross data center has become a key technology. The system, mainly about the resource scheduling algorithms across data center, presents the framework and major function of the cloud federation environment cross the datacenter. Furthermore, through Cloudsim, a Web server based system platform was built. Finally, the system proved that it can meet the complicated large-scale demand of users as well as increase the efficiency and profit of resource scheduling among the providers in cloud federation.

The cloud computing market is composed by many cloud service providers, It is a key problem about how to choose and to determine the appropriate the competitiveness partners between the major cloud service providers. For this problem we propose a optimization algorithm based on graph theory solution. First we should clearly consider the factors in choosing the partner's .On this basis we establish the mathematical model of the cloud service provider partners. How to select the tender of cloud service providers in the problem, the paper gives the optimization algorithm based on graph theory, last we give an example to verify the effectiveness of the algorithm.

Cloud computing cost-effective, and scalable characteristics can be an effective solution to teaching college laboratory teaching uneven distribution of resources, updates slow, the shared low degree. Analysis of cloud computing at home and abroad in the application on the basis of education, the paper put forward and design college laboratory teaching management system based on hybrid cloud management function, and provide a good guide for colleges and universities to achieve cloud computing experimental teaching management.

Eleven C19-diterpenoid alkaloids reported in Shi's paper were isolated or synthesized. Their 13C NMR and DEPT spectra were recorded using (CD3)2CO+TFA as solvents. Comparison of the acquired NMR data with those reported in Shi's paper, in combination with the fact that all alkaloids, expect for 8, 27, and 28, reported in Shi's paper were isolated using TFA as part of solvent system, led to the following revisions of Shi's paper: (1) compounds 1–4, 6, 7a, 9–26 should be their respective trifluoroacetates. Their structures were revised as 1a–4a, 6a, 7a′, 9a–26a; (2) compounds 7, 27a, and 28a are trifluoroacetates of free bases 8, 27, and 28, respectively; compound 7 should be corrected as 7b; (3) ring A of free bases (such as 8, 27, and 28) exists as chair conformation; while ring A of the protonated versions (such as 7, 27a, 28a, 6a, 9a–26a) exists as boat conformation. Consequently, compounds 7 and 8 are apparently not a pair of conformational isomers, instead, they are indeed a free base and its protonated version existing as a trifluoroacetate, respectively; (4) ‘new’ compounds 6, 13, and 15 are the protonated versions 6a, 13a, and 15a, respectively, of the corresponding known alkaloids, aconifine, deoxyaconitine, 14-benzoylaconine. In addition, all 1H (13C) NMR data for the free bases of new compounds 8, 9, 10, 17, and 24 (Tables 3 and 4) were also assigned based on their 2D NMR spectra.

Phytochemical investigation of the whole herbs of Aconitum tanguticum (Maxim.) Stapf var. trichocarpum Hand.-Mazz. led to the isolation of one heteratisine-hetidine-type bis-diterpenoid alkaloid, trichocarpidine (1), three hetidine-hetisine type bis-diterpenoid alkaloids, trichocarpinine A–C (2–4, resp.), together with nine known compounds. Their structures were elucidated by spectroscopic analyses.

A client-based cloud computing market polyinstance combination purchase decision model is constructed in this paper. Starting with a single objective constraint model that optimize cost and service time, in which features of different instance types and standards were combined. The proposed model is solved by genetic algorithm. Then, various user’s needs are taken into full consideration by formulating a double objective constraint model to achieve the objective of minimizing the user purchase cost and service time at the same time.

The cardiac effect of thirty-eight diterpenoid alkaloids was evaluated on the isolated bullfrog heart model. Among them, twelve compounds exhibited appreciable cardiac activity, with compounds 3 and 35 being more active than the reference drug lanatoside. The structure-cardiac activity relationships of the diterpenoid alkaloids were summarized based on our present and previous studies [2]: i) 1α-OMe or 1α-OH, 8-OH, 14-OH, and NH (or NMe) are key structural features important for the cardiac effect of the aconitine-type C19-diterpenoid alkaloids without any esters. C18-diterpenoid alkaloids, lycoctonine-type C19-diterpenoid alkaloids, and the veatchine- and denudatine-type C20-diterpenoid alkaloids did not show any cardiac activity; ii) the presence of 3α-OH is beneficial to the cardiac activity; iii) the effect on the cardiac action of 6α-OMe, 13-OH, 15α-OH, and 16-demethoxy or a double bond between C-15 and C-16 depends on the substituent pattern on the nitrogen atom.

The user interesting degree evaluation index is designed to fulfill the users’ real needs, which includes the user’ attention degree of commodity, hot commodity and preferential commodity. User interesting degree model (UIDM) is constructed to justify the value of user interesting degree; the personalization approach is presented; operations of add and delete nodes (branches) are covered in this paper. The improved e-catalog is more satisfied to users’ needs and wants than the former e-catalog which stands for enterprises, and the improved one can complete the recommendation of related products of enterprises.

Bioassay-guided fractionation of an n-BuOH extract of the lateral roots of Aconitum carmichaeli. led to the isolation of 5 cardioactive C(19)-diterpenoid alkaloids: N-deethylaconine (1), beiwutinine (2), hypaconine (3), mesaconine (4), and 15α-hydroxyneoline (5). N-Deethylaconine and beiwutinine are new aconitine-type C(19)-diterpenoid alkaloids. Hypaconine was isolated from this species for the first time. Among them, mesaconine, hypaconine, and beiwutinine showed the strongest cardiac actions on the isolated perfused bullfrog heart. Furthermore, mesaconine has protective effects, including improved inotropic effect and left ventricular diastolic function, on myocardial ischemia-reperfusion injury in rat at a dose of 10(-9) mol/L. However, mesaconine has almost no effect on heart rate.

Two novel monoterpenoid indole alkaloids, aminocadambines A (1) and B (2), characterized by tetrahydrofuran and 1,2,3,4-tetrahydropyridine rings, were isolated from the leaves of Neolamarckia cadamba. Their structures were elucidated on the basis of spectroscopic and computational methods. The absolute configuration of 1 was established by CD analysis. A plausible biosynthetic pathway for 1 and 2 is proposed. (C) 2010 Elsevier Ltd. All rights reserved.

Three new C19-diterpenoid alkaloids, giraldines A (1), B (3) and C (4), were isolated from the roots of Delphinium giraldii Diels, together with three known C19-diterpenoid alkaloids, dihydrogadesine (5), tatsiensine (6) and siwanine A (7), as well as their structures were elucidated by chemical evidence and spectral analyses, including m, MS, 1D NMR and 2D NMR.

One new C19-diterpenoid alkaloid, named liangshantine (1), and three new C20-diterpenoid alkaloids, liangshansines A–C (2–4, resp.), as well as eight known compounds, were isolated from the roots of Aconitum liangshanicum. The structures of these new alkaloids were elucidated by spectroscopic methods.

We report on the fabrication of ion exchangeable microstructures by femtosecond laser direct writing of an ion exchange photopolymer, poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS). The resultant microstructures are negatively charged in aqueous solution, and can adsorb positively charged species, such as metal ions, nanoparticles, and proteins by electrostatic interaction, forming functional components for chip functionalization. In addition, it is possible to modify the microstructures with positively charged species that make the microstructures sensitive to negatively charged species. As a typical example, a crossed 3D microvessel functionalized with antibodies was fabricated, which reveals great potential for organ-on-a-chip systems. The fabrication of ion exchangeable microstructures holds great promise for flexible chip functionalization.

Trichocarpinine (1), the first hetidine–hetisine type bisditerpenoid alkaloid, was isolated from the whole herbs of Aconitum tanguticum var. trichocarpum. Its structure was determined by a combination of spectroscopic techniques, including HR-ESI-MS and 1D- and 2D-NMR experiments. Its plausible biogenetic pathway was proposed as well (Scheme).

Two novel C-nor-B-homo aconane-type diterpenes 4 and 5, featuring a unique eight-membered ring system, were obtained by the treatment of C-nor-C19-diterpenoid alkaloid 3 with HNO2 in 8% and 21% yields, respectively. Structures of these two compounds were established based on the combination of spectroscopic data, including HRESIMS, 1D and 2D NMR data. A plausible mechanism for the formation of 4 and 5 is also presented.

From the whole herbs of Delphinium majus, three new C(19)-diterpenoid alkaloids, majusines A-C (1-3), and six new C(20)-diterpenoid alkaloids, majusimines A-D (4-7) and majusidine A and B (8 and 9), have been isolated, together with 15 known compounds. The structures of compounds 1-9 were elucidated by spectroscopic data interpretation.

In order to study the slagging characteristics of boiler combustion liners during pulverized coal stream combustion, the slag samples on the surface of combustion liner were investigated by X-ray diffractometry, scan electron microscopy and energy dispersive X-ray analysis, and the transformation characteristics of the compositions and crystal phases were studied. The results show that the size of slag granules decreases as the slagging temperature increases; the crystallinity of coal ash I reduces to about 48.6% when the temperature is increased up to 1 350 °C, and that of the coal ash II reduces to about 65% when the temperature is increased up to 1 500 °C; the encroachment of molten coal ash to the combustion liner is strengthened. At the same time, the diffusion and the segregation of the compositions in combustion liners have selectivity, which is in favor of enhancing the content of crystal phases, weakening the conglutination among molten slag compositions and combustion liner, and avoiding yielding big clinkers. But the diffusion of the compositions in combustion liners increases the porosity and decreases the mechanical intensity of combustion liner, and makes the slag encroachment to the liner become more serious.

A novel approach to the highly functionalized taxane ABC ring system through chemical conversion of the C19-diterpenoid alkaloid deltaline (1) was achieved in six steps (1→17) in 18% overall yield mainly by Grob fragmentation, fission of the Δ9(14) double bond, followed by aldol condensation, and Pelletier's cleavage process.

A new franchetine-type C 19 -diterpenoid alkaloid 3-hydroxyfranchetine 1 and a new aconitine-type C 19 -diterpenoid alkaloid atropurpursine 2 have been isolated from the roots of Aconitum hemsleyanium var. atropurpureum . The structures of these new alkaloids were established on the basis of spectral data.

Three new lycoctonine-type C19-diterpenoid alkaloids, laxicymine 1, laxicymisine 2, and laxicyminine 3 have been isolated from the whole herb of Delphinium laxicymosum var. pilostachyum W.T. Wang. Their structures were established by spectra data.

Through using the Monte Carlo method to calculate the fraction distributions of the emission scattered within an emitting, absorbing and scattering gray medium with a vacuum or a cold black wall, a new solution for the angular distributions of radiative intensity in the medium is presented. The angular distributions of intensity in one or more points, or even everywhere, can be calculated from the given distributions of temperature and radiative properties in the medium without the requirement of radiative equilibrium. For the emitting, absorbing, isotropic scattering, parallel-plane, gray media, some important relationships between the new and the formal solutions of the radiative transfer equation are delivered. Validation results for the angular distributions of radiative intensity got for the medium with uniformly specified distributions of temperature and radiative property and optical thickness less than 2.0 demonstrate that the new solution agrees well with the formal solution in the same condition. The work presented in this paper extends the application of the common Monte Carlo methods. In the recent future, more complicated parallel-plane cases will be studied by the same idea, especially with different kinds of wall conditions and/or anisotropic scattering.

A new franchetine-type (leueandine 1) and two new lycoctonine-type [potanisines F (3) and G (5)] C19-diterpenoid alkaloids have been isolated from the roots of Aconitum hemsleyanum var. leueanthus and Delphinium potaninii, respectively, and their structures were established on the basis of spectral data.

A parallel-plane space filled with absorbing, emitting, isotropically scattering, gray medium is studied in this paper. The boundary intensity and boundary temperature profiles are calculated for the inverse analysis. For the simultaneous estimation of temperature, absorption and scattering coefficient profiles in the medium, the sum of residuals of boundary intensity and temperature after being weighted by a balance factor is minimized through using a Newton-type iteration algorithm and the least-squares method. To avoid over-updating for the parameters, the relative updating magnitude during the iteration process is constrained not to be >0.5. It is shown that the boundary intensity measurement alone is not enough to estimate simultaneously the temperature (source) and the radiative properties (both absorption and scattering coefficients) when the measurement data contain sensitive random errors. The boundary temperature measurement can serve as a necessary supplementation to the boundary intensity to make this kind of inverse radiative transfer problem resolvable. It was shown that a compensation relationship between absorption and scattering coefficients makes it difficult to fix them accurately. Parabolic profiles for the three parameters are used to validate the estimation method. When the optical thickness approaches 4.0, the results for the radiative properties are not acceptable, although the result for temperature profile is reasonable. This means the method needs further improvements.

From the whole herb of Delphinium laxicymosum var pilostachyum, three new C20-diterpenoid alkaloids, laxipilostine, laxipilosdine, and laxipilosline (1-3), were isolated, together with fourteen known diterpenoid alkaloids. Their structures were determined by extensively interpretation of their spectroscopic data (1D- and 2D-NMR, MS, and IR).

Two chlorin derivatives, rhodochlorin dimethyl ester (7) and chlorin-e6 trimethyl ester (8), were prepared from methyl pheophobide a (6) through base-degradation of the E ring and methylation of the carboxylic acids. Full assignments of the 1H, 13C and 15N magnetic resonance spectra of compounds 7 and 8 were made by 2D NMR techniques (1H-1H COSY, 1H-13C HMQC, 1H-13C HMBC, 1H-15N HMBC).

From the roots of Aconitum sinomontanum, five new norditerpenoid alkaloids, sinomontanitines A (1) and B (2), sinomontanines A (3), B (4) and C (5), were isolated together with the known alkaloids lappaconitine (6) and ranaconitine (7), The structures of the new alkaloids were determined by spectral analysis.

Four new norditerpenoid alkaloids, leueantines A (1), B (2), C (3), and D (4), were isolated from the roots of Aconitum hemsleyanum var. leueanthus. The structures of 1-4 were established by spectroscopic evidence.

Thirty three C19-diterpenoid alkaloids, twenty-two prepared from known C19-diterpenoid alkaloids and eleven isolated from Aconitum and Delphinium spp. were evaluated for their cardiac activity in the isolated bullfrog heart assay. Among them, eleven compounds exhibited cardiac activity, with average rate of amplitude increase in the range of 16-118%. Compound 7, mesaconine (17), hypaconine (25), and beiwutinine (26) exhibited strong cardiac activities relative to the reference drug. The structure-activity relationship data acquired indicated that an alpha-hydroxyl group at C-15, a hydroxyl group at C-8, an alpha-methoxyl or hydroxyl group at C-1, and a secondary amine or N-methyl group in ring A are important structure features necessary for the cardiac activities of the aconitine-type C19-diterpenoid alkaloids without any ester groups. In addition, an alpha-hydroxyl group at C-3 is also helpful for the cardiac activity of these alkaloids.

New aconitine-type C19-diterpenoid alkaloids, N-deethylaconine (I) and beiwutinine (II), are isolated together with hypaconine, mesaconine and 14α-hydroxyneoline.

A series of new bisbenzylisoquinoline alkaloids was partially synthesized from tetrandrine and fangchinoline and evaluated for their ability to reverse P-glycoprotein-mediated multidrug resistance (MDR) in cancer cells. All the test compounds increased the intracellular accumulation rate of rhodamine 123 in MDR cells (Bel7402 and HCT8), and most exhibited more potent MDR-reversing activity relative to the reference compound verapamil. Compounds 8, 10, 13, and 14 enhanced intracellular accumulation of doxorubicin in Bel7402 and HCT8 cells.

The relative reactivity of three hydroxyl groups in aconitine toward acetylation, chlorination, sulfonylation, and oxidation has been studied in this paper. The reduction of C-3 ketone and C-15 ketone derivatives of aconitine was also investigated. It was found that (1) the relative reactivity of three hydroxyl groups toward acetylation, chlorination, and sulfonylation is 3-OH13-OH15-OH; (2) 3-OH is much more reactive than 15-OH toward oxidation; and (3) reduction of the carbonyl group at C-3 with NaBH(4) generated a pair of C-3 epimers, while the reduction products of the carbonyl group at C-15 depend largely on the specific reducing agent and the absolute configuration of 16-OCH(3). When the substrate has 16β-OCH(3), its carbonyl group at C-15 can be reduced with NaBH(4) to yield exclusively the 15α-OH-containing product. Upon replacement of reducing agent NaBH(4) with LiAlH(4), the C-15 carbonyl group can be reduced to yield a pair of C-15 epimers. On the other hand, when the substrate has 16α-OCH(3), C-15 carbonyl group can only be reduced to generate 15α-OH-containing product.

Phytochemical investigation of the leaves of Trichilia connaroides afforded 12 new limonoids with phragmalin- (1-11) and mexicanolide-type skeletons (12). The structures of these limonoids, including the absolute configuration of 3, were determined by spectroscopic analysis. Compounds 6 and 8 showed moderate cytotoxicity against HL-60 cells.