海洋生物质的热解特性与动力学研究

以定生浒苔、漂浮浒苔、石莼、大叶藻、海带、龙须菜和裙带菜7种海洋生物质为研究对象,以1种草类生物质玉米秸秆、1种木质类生物质锯末为对照,用热重分析法对其热解过程及其动力学规律进行了研究。利用TG-DTG-DTA曲线分析了它们的基本热解特性。结果表明,整个热解过程主要为干燥失水、剧烈失重和缓慢失重3个阶段,海洋生物质的Tmax明显低于2类陆生生物质,而且大叶藻的热解稳定性相对较高,而漂浮浒苔的热解稳定性较低,燃烧特性较好。同时,用Coats-Redfern法求得相应的活化能E和频率因子A,发现3类生物质的热解反应机理函数不同。     

Thermal degradation studies and kinetic modeling of cardoon (Cynara cardunculus) pyrolysis using thermogravimetric analysis (TGA)

A key element in the design of sustainable pyrolysis processes is the thermal degradation kinetics of biomass. In this work, pyrolysis tests for cardoon (Cynara carduculus) stems and leaves were performed in a non-isothermal thermogravimetric analyzer (TGA) in order to determine the thermal degradation behavior of both stems and leaves. The kinetic parameters of the process were evaluated using three different kinetic models, the independent parallel reaction model, KAS and OFW iso-conversional model. Good agreement with the experimental TGA data was observed for all models, the best being with the independent parallel reaction model. A variance in the activation energy with conversion was observed when the KAS and OFW models were employed, which reveals that the pyrolysis of cardoon progresses through more complex and multi-step kinetics.     

Stochastic stable population growth in integral projection models: theory and application

Stochastic matrix projection models are widely used to model age- or stage-structured populations with vital rates that fluctuate randomly over time. Practical applications of these models rest on qualitative properties such as the existence of a long term population growth rate, asymptotic log-normality of total population size, and weak ergodicity of population structure. We show here that these properties are shared by a general stochastic integral projection model, by using results in (Eveson in D. Phil. Thesis, University of Sussex, 1991, Eveson in Proc. Lond. Math. Soc. 70, 411-440, 1993) to extend the approach in (Lange and Holmes in J. Appl. Prob. 18, 325-344, 1981). Integral projection models allow individuals to be cross-classified by multiple attributes, either discrete or continuous, and allow the classification to change during the life cycle. These features are present in plant populations with size and age as important predictors of individual fate, populations with a persistent bank of dormant seeds or eggs, and animal species with complex life cycles. We also present a case-study based on a 6-year field study of the Illyrian thistle, Onopordum illyricum, to demonstrate how easily a stochastic integral model can be parameterized from field data and then applied using familiar matrix software and methods. Thistle demography is affected by multiple traits (size, age and a latent "quality" variable), which would be difficult to accommodate in a classical matrix model. We use the model to explore the evolution of size- and age-dependent flowering using an evolutionarily stable strategy (ESS) approach. We find close agreement between the observed flowering behavior and the predicted ESS from the stochastic model, whereas the ESS predicted from a deterministic version of the model is very different from observed flowering behavior. These results strongly suggest that the flowering strategy in O. illyricum is an adaptation to random between-year variation in vital rates.     

Paleopharmacology and pollen: theory,method, and application

Parasitism was a universal human condition. Because of this, people developed herbal medicines to treat parasites as part of their pharmacopoeias. We propose that it is possible to recover evidence of medicinal plants from archaeological sites and link their use to specific health conditions. This is a multidisciplinary approach that must involve at least paleoethnobotanists, archaeoparasitologists, paleopathologists, and pharmacologists.     

Predicting functional sites in proteins: site-specific evolutionary models and their application to neurotransmitter transporters

Currently there exist several computational methods for predicting the functional sites in a set of homologous proteins based on their sequences. Due to difficulties in defining the functional site in a protein, it is not trivial to compare the performance of these methods, evaluate their limitations and quantify improvements by new approaches. Here, we use extensive mutation data from two proteins, Lac repressor and subtilisin, to perform such an analysis. Along with the evaluation of existing approaches, we describe a site class model of evolution as a tool to predict functional sites in proteins. The results indicate that this model, which simulates the evolution process at the amino acid level using site-specific substitution matrices, provides the most accurate information on functional sites in a given protein family. Secondly, we present an application of this model to neurotransmitter transporters, a superfamily of proteins of which we have limited experimental knowledge. Based on this application we present testable hypotheses regarding the mechanism of action of these proteins.     

Convolution-based one and two component FRAP analysis: theory and application

The method of fluorescence redistribution after photobleaching (FRAP) is increasingly receiving interest in biological applications as it is nowadays used not only to determine mobility parameters per se, but to investigate dynamic changes in the concentration or distribution of diffusing molecules. Here, we develop a new simple convolution-based approach to analyze FRAP data using the whole image information. This method does not require information about the timing and localization of the bleaching event but uses the first image acquired directly after photobleaching to calculate the intensity distributions, instead. Changes in pools of molecules with different velocities, which are monitored by applying repetitive FRAP experiments within a single cell, can be analyzed by means of a global model by assuming two global diffusion coefficients with changing portions. We validate the approach by simulation and show that translocation of the YFP-fused PH-domain of phospholipase Cδ1 can be quantitatively monitored by FRAP analysis in a time-resolved manner. The new FRAP data analysis procedure may be applied to investigate signal transduction pathways using biosensors that change their mobility. An altered mobility in response to the activation of signaling cascades may result either from an altered size of the biosensor, e.g. due to multimerization processes or from translocation of the sensor to an environment with different viscosity. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Phi-value analysis of a linear, sequential reaction mechanism: theory and application to ion channel gating

We derive the analytical form of a rate-equilibrium free-energy relationship (with slope Phi) for a bounded, linear chain of coupled reactions having arbitrary connecting rate constants. The results confirm previous simulation studies showing that Phi-values reflect the position of the perturbed reaction within the chain, with reactions occurring earlier in the sequence producing higher Phi-values than those occurring later in the sequence. The derivation includes an expression for the transmission coefficients of the overall reaction based on the rate constants of an arbitrary, discrete, finite Markov chain. The results indicate that experimental Phi-values can be used to calculate the relative heights of the energy barriers between intermediate states of the chain but provide no information about the energies of the wells along the reaction path. Application of the equations to the case of diliganded acetylcholine receptor channel gating suggests that the transition-state ensemble for this reaction is nearly flat. Although this mechanism accounts for many of the basic features of diliganded and unliganded acetylcholine receptor channel gating, the experimental rate-equilibrium free-energy relationships appear to be more linear than those predicted by the theory.     

Cobalt isothiocyanate coordination polymers constructed from isomeric bis(pyridylmethyl)piperazine ligands: Ribbon and chain motifs and a novel (3,4)-connected supramolecular layer

Slow diffusion conditions have afforded a pair of cobalt isothiocyanate coordination polymers incorporating the flexible and hydrogen-bonding capable organodiimines N,N′-bis(3-pyridylmethyl)piperazine (3-bpmp) and N,N′-bis(4-pyridylmethyl)piperazine (4-bpmp), which were characterized by single-crystal X-ray diffraction and spectral and elemental analysis. While both [Co(NCS)₂(3-bpmp)₂]_n (1) and {[Co(NCS)₂(H₂O)₂(4-bpmp)] · 2H₂O}_n (2) possess one-dimensional (1-D) coordination polymer units, the donor disposition within the organodiimine promotes significant structural disparities. Compound 1 displays a 1-D double-chain motif, where each cobalt ion is bridged by two exobidentate 3-bpmp ligands. In contrast, compound 2 manifests a single chain pattern, with only one tethering 4-bpmp ligand joining adjacent cobalt ions. Extensive hydrogen-bonding patterns within the structure of 2 results in an intriguing supramolecular 2-D (3,4)-connected layer with (4.6²)₂(4².6².8²) topology. Thermal properties of these materials are also discussed.     

Top-down elasticity analysis and its application to energy metabolism in isolated mitochondria and intact cells

This paper reviews top-down elasticity analysis, which is a subset of metabolic control analysis. Top-down elasticity analysis provides a systematic yet simple experimental method to identify all the primary sites of action of an effector in complex systems and to distinguish them from all the secondary, indirect, sites of action. In the top-down approach, the complex system (for example, a mitochondrion, cell, organ or organism) is first conceptually divided into a small number of blocks of reactions interconnected by one or more metabolic intermediates. By changing the concentration of one intermediate when all others are held constant and measuring the fluxes through each block of reactions, the overall kinetic response of each block to each intermediate can be established. The concentrations of intermediates can be changed by adding new branches to the system or by manipulating the activities of blocks of reactions whose kinetics are not under investigation. To determine how much an effector alters the overall kinetics of a block of reactions, the overall kinetic response of the block to the intermediate is remeasured in the presence of the effector. Blocks that contain significant primary sites of action will display altered kinetics; blocks that change rate only because of secondary alterations in the concentrations of other metabolites will not. If desired, this elasticity analysis can be repeated with the primary target blocks subdivided into simpler blocks so that the primary sites of action can be defined with more and more precision until, with sufficient subdivision, they are mapped onto individual kinetic steps. Top-down elasticity analysis has been used to identify the targets of effectors of oxygen consumption in mitochondria, hepatocytes and thymocytes. Effectors include poisons such as cadmium and hormones such as tri-iodothyronine. However, the method is more general than this; in principle it can be applied to any metabolic or other steady-state system.     

Measurement of cytokines by bioassays: theory and application

A large number of cytokines have been characterized, of which several have proved successful in the clinic as biotherapeutic agents for malignant, infectious or autoimmune diseases. As biologically active proteins, they cannot be fully characterized by physicochemical methods alone. Thus, biological assays (bioassays) have become increasingly important for their biological characterization and potency determinations. Since cytokines exert various biological activities in vitro, cultured cell line-based bioassay methods have mainly been developed to quantify potency. Such bioassays, like all biological systems, are inherently variable. Thus, measurement of potency of a particular cytokine must be made relative to a common, stable, reference preparation of the same cytokine to permit valid inter-assay and inter-laboratory comparisons. The development and establishment of appropriate primary reference preparations as World Health Organization (WHO) International standards (IS) and reference reagents (RR) is essential for the standardization of bioassays. This review addresses the practical and statistical considerations for the development of valid bioassays, the preparation and use of WHO IS and RR and, in brief, the types of bioassay methods applicable to potency measurements of individual cytokines. More extensive details for the potency determinations of tumor necrosis factor-alpha (TNF-alpha), related cytokines, and biotherapeutic anti-TNF-alpha products are provided.     

One-dimensional nickel and cobalt phthalate coordination polymers incorporating the kinked dipodal organodiimine 4,4′-dipyridylamine: Hydrothermal synthesis, structural characterization and thermal properties

Hydrothermal synthesis has afforded a family of three structurally related metal phthalate (pht) 1-D coordination polymers incorporating the kinked dipodal organodiimine 4,4′-dipyridylamine (dpa), with a general formulation of [L₂M(dpa)₂M(H₂O)₄] · H₂O (L = pht, M = Co, 1, M = Ni, 2; L = 4-methylphthalate (4-mpht), M = Co, 3). Single crystal X-ray diffraction of 1 and 2 revealed the presence of one-dimensional (1-D) polymeric chains consisting of [M(H₂O)₄]²⁺ and [M(pht)₂]²⁻ subunits linked through dpa tethers. These chains in turn conjoin into pseudo 2-D layers and 3-D networks via extensive supramolecular hydrogen bonding pathways. An extremely similar structure is observed for 3 despite the presence of the bulkier methyl group substituent. 1-3 were further characterized via infrared spectroscopy and elemental and thermogravimetric analysis. 1-3 represent the first dicarboxylate coordination polymers incorporating dpa tethering ligands.     

A new method for immunologically marking prey and its use in predation studies

We introduce a new method for immunologically examining predator gut contents. It differs from previously described gut content analyses because it does not require the development of prey-specific antibody probes. Instead, insect prey were marked with a readily available antigen, rabbit immunoglobulin G (IgG). We then assayed predators that had fed on IgG labeled prey with an enzyme-linked immunosorbent assay (ELISA) using goat anti-rabbit IgG. Of the predator species that fed on the IgG labeled prey, 98.8% of those with chewing mouthparts scored positive for IgG 1 h after feeding. Our prey-labeling ELISA was less efficient for detecting IgG prey remains in predators with piercing/sucking mouthparts. Only 29.5% of these individuals scored positive for rabbit IgG in their guts 1 h after feeding. An additional study was conducted to measure the retention time of IgG-labeled prey in the guts of two species of predators with chewing mouthparts. Results from this experiment showed that the retention time varied depending on the predator and prey species examined. Results from these studies indicate that this marking technique could have widespread use for analyzing the gut contents of predators with chewing mouthparts, but it has limited application for those predators with piercing/sucking mouthparts. This article presents the results of research only. Mention of a proprietary product does not constitute an endorsement or recommendation for its use by the USDA.     

Application of fuzzy theory and PROMETHEE technique to evaluate suitable ecotechnology method: A case study in Shihmen Reservoir Watershed, Taiwan

With the increase in industrial development and improper land uses, Taiwan has faced the extinction crisis and is seeing the signs of nature, revenge in the forms of frequent landslides, floods, and debris flows in recent years. The government has strongly promoted the concept of ecotechnology in the hope of maintaining the ecosystem and its integrity. However, the application of ecotechnology is still in its infancy, so there is currently no objective evaluation standard to assess its effectiveness. Deficiencies in the scientific approach to quantify the results are due to current disputes and bottlenecks in its implementation. In order to seek reasonable and feasible methods to overcome the deficiencies in the implementation of the scientific approach, this study collected domestic and international ecological evaluation models to develop innovative processes that utilize ecological, safety, and cost indices. First, the commonly used ecotechnology methods for river embankment were acquired from the governmental departments. Second, the ecological, safety and cost indices for the acquired ecotechnology methods and construction sites were analyzed and quantified using fuzzy theory. Third, indices of ecotechnology methods were linked with those of construction sites for the PROMETHEE technique evaluation for suitable ecotechnology method selection. A practical construction case located in Shihmen reservoir watershed was chosen for evaluation and verification. The results show that the developed model can provide useful information for decision making while performing ecotechnology engineering.     

Chaney and Ruiz Revilla: Sampling Methods: Comment 1

The following comments pertain to Sampling Methods and Interpretation of Correlation: A Comparative Analysis of Seven Cross-Cultural Samples, Richard P. Chaney and Rogelio Ruiz Revilla, AA 71:597–633.