In this paper, we apply discrete-event system techniques to model and analyze the execution of concurrent software. The problem of interest is deadlock avoidance in shared-memory multithreaded programs. We employ Petri nets to systematically model multithreaded programs with lock acquisition and release operations. We define a new class of Petri nets, called Gadara nets, that arises from this modeling process. We investigate a set of important properties of Gadara nets, such as liveness, reversibility, and linear separability. We propose efficient algorithms for the verification of liveness of Gadara nets, and report experimental results on their performance. We also present modeling examples of real-world programs. The results in this paper lay the foundations for the development of effective control synthesis algorithms for Gadara nets.

Deadlock avoidance in shared-memory multithreaded programs is receiving increased attention as multicore architectures and parallel programming are becoming more prevalent. In our on-going project, called Gadara, the objective is to control the execution of multithreaded programs in order to avoid deadlocks by using techniques from discrete-event control theory. In this project, Petri nets are employed to model parallel programs. This paper formally defines the class of Petri nets that emerges from modeling multithreaded programs, called Gadara nets. Gadara nets are related to, but different from, other classes of nets that have been characterized in deadlock analysis of manufacturing systems. The contributions of this paper include: (i) formal definition of Gadara nets and of controlled Gadara nets; (ii) a behavioral analysis of Gadara nets for liveness and reversibility using siphons; and (iii) identification of a convexity-type property for the set of live markings.

Two enantiomeric pairs of meroterpenoids, (-)- and (+)-rhodonoids A (1a and 1b) and B (2a and 2b), were isolated unprecedentedly from partially racemic mixtures that naturally occurred in Rhododendron capitatum. Their structures were fully determined by spectroscopic data, X-ray crystallography, and electronic circular dichroism analysis. Compounds 1a and 1b are the first examples of meromonoterpenes featuring a unique 6/6/6/4 ring system. Compounds 2a and 2b showed PTP1B inhibitory activity.

Background:This research will establish the ultraviolet colorimetric method to determine the total flavonoid content in different species and different parts of Abelmoschus esculentus L.Materials and Methods:We establish the reversed-phase high-performance liquid chromatograph (RP-HPLC) method to determine the content of the three flavonoid glycosides in different species and different parts of the A. esculentus. Adopt the NaNO2-Al (NO3)3-NaOH colorimetric method to determine the total flavonoid content; at the same time, adopt the RP-HPLC method to determine the contents of the three flavonoid glycosides. Using the methods of ultraviolet colorimetry and RP-HPLC, we determined and analyzed the total flavonoid content and the content of the three flavonoid glycosides in different species and different parts of A. esculentus.Results:There are great distribution differences of the total flavonoids and the three flavonoid glycosides in different species and parts of A. esculentus. Among them, the content of the effective constituents in the flower is relatively high, next is in the fruit. In the different species of A. esculentus, the content of the flavonoids of finger relatively high. The HPLC method established in this research is simple and convenient and its results are accurate and reliable. In addition, it has a very good repeatability.Conclusion:The results provided the reference data for the medicinal use of A. esculentus and it can be used in quality analyzing of its effective constituents.

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Chemical investigation on the aerial parts of Rhododendron capitatum resulted in the discovery of five enantiomeric pairs of new meroterpenoids, (+)-/(-)-rhodonoids C (1a and 1b), E (3a and 3b), F (4a and 4b), and (-)-/(+)-rhodonoids D (2a and 2b) and G (5a and 5b). These enantiomeric pairs existed as partial racemates in a plant and were obtained by chiral HPLC separation. Their structures with absolute configurations were assigned by spectroscopic data, single-crystal X-ray diffraction, and ECD analysis. Compounds 1a and 1b are the first pair of meromonoterpenes incorporating an unprecedented 6/6/6/5 ring system, and 1a showed antiviral activity against herpes simplex virus type 1 (HSV-1) in vitro. Compounds 2a and 2b are the first examples of meromonoterpenes featuring a unique 6/6/5/5 ring system.

Background:Abelmoschus esculentus L. is a healthy vegetable belonging to the family Malvaceae. This article reports the contents of total phenolics (TP) and total flavonoids (TF) in 80% methanol extracts of the flower (FL), fruit (FR), leaf (L), and seed (S) of A. esculentus, and in 0, 10, 30, 50, and 70% methanol eluates (ME), through the HP-20 column chromatography of 80% of the methanol fruit extract after it is defatted with petroleum and extracted with ethyl acetate. All the names of the samples are shortened for AEE-FL, AEE-FR, AEE-L, AEE-S and 0% MEF-WE, 10% MEF-WE, 30% MEF-WE, 50% MEF-WE, 70% MEF-WE respectively. In addition, the effects of the aforementioned extracts on 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) radical-scavenging and on ferric reducing antioxidant power (FRAP) have been evaluated.Materials and Methods:The antioxidant activity of the extracts and the enrichment fraction of A. esculentus were also evaluated by two assays, the DPPH radical-scavenging and ferric reducing antioxidant power (FRAP). The content measurement of TF and TP adopts the UV-2102 PCS method, and the measurement of the antioxidant activity adopts the Infinite M 200 method.Results:The experiment results show that all the different parts and different enrichment fractions of the water extracts of A. esculentus contain phenolics and flavonoids. Through the research of antioxidant activity we know that all the parts of the methanol extracts and different enrichment fractions of water extracts in the A. esculentus have the effect of scavenging free radicals, among which the antioxidant activity in the 50% MEF-WE part is the strongest. Here, the main components of antioxidant activity must be the flavonoids and phenolics, and furthermore, we know that there is a direct relationship between the contents of flavonoids and phenolics and the antioxidant activity.Conclusion:The study suggests that A. esculentus may be the potential rich source of natural antioxidant. The experiment result provided a scientific basis for the further research and development of A. esculentus.

Abstract-We investigate the synthesis of optimal livenessenforcing control policies for Gadara nets, a special class of Petri nets that arises in the modeling of the execution of multithreaded computer programs for the purpose of deadlock avoidance. We consider maximal permissiveness as the notion of optimality. Deadlock-freeness of a multithreaded program corresponds to liveness of its Gadara net model. We present a new control synthesis algorithm for liveness enforcement of Gadara nets that need not be ordinary. The algorithm employs structural analysis of the net and synthesizes monitor places to prevent the formation of a special class of siphons, termed resource-induced deadlymarked siphons. The algorithm also accounts for uncontrollable transitions in the net in a minimally restrictive manner. The algorithm is generally an iterative process and converges in a finite number of iterations. It exploits a covering of the unsafe states that is updated at each iteration. The proposed algorithm is shown to be correct and maximally permissive with respect to the goal of liveness enforcement.