Competition Phenomena Research Articles

The Occurrence of Apparent Competition and Apparent Mutualism in a Modeled Greenhouse System with Two Non-competing Pests and a Shared Biocontrol Agent.

This work puts forward a dynamical population model to qualitatively reproduce the phenomena of apparent competition and apparent mutualism found in an experiment with two arthropods being attacked by a predator in a context of pest biological control in greenhouse crops. The two agricultural pests consist of one species of thrips (Frankliniella occidentalis (Pergande 1895)) and one species of whiteflies (Trialeurodes vaporariorum Westwood, 1956), and the shared predator is a predatory mite (Amblyseius swirskii Athias-Herriot, 1962). The predatory mite is the biocontrol agent employed in order to achieve the biological control. The proposed model successfully reproduces this density mediated indirect interactions between pests when their carrying capacities are increased. Moreover, the pests' final population levels may depend on their initial densities and those of their predator. With these results, the proposed model may have the potential to assess whether these indirect pest interactions disrupt or enhance biological control. Additionally, it can also be used as an ancillary tool to theoretically assess the effects of pest biocontrol strategies in the referred experimental setup.

Understanding the interaction mechanism of algal cells and soluble algal products foulants in forward osmosis dewatering

Forward osmosis (FO) has increasingly been an energy saving technology in microalgae dewatering, whereas membrane fouling is still a major obstacle for FO application. To explore the fouling mechanism of algal cells and their organic matters during microalgal FO dewatering process, Chlorella vulgaris and Scenedesmus obliquus were adopted as algae species, and the algae-derived foulants including algae cells, soluble algal products (SAP) and algal broth were used as feed solutions. The water fluxes behaviors of algal foulants had been investigated, and the dissolved organic carbon (DOC), protein and carbohydrates proportions of the feed solutions were then characterized, followed by the scanning electronic microscopy (SEM) and the analysis of extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory for the FO membrane foulants. The results indicated that algal broth resulted in the fastest flux decline due to the combined fouling between SAP and algae cells. The competitive adsorption phenomenon between cells and SAP was found in C. vulgaris broth but not in S. obliquus, resulting in a high protein content loss in the feed solution of C. vulgaris. The fouling potential of those individual and combined feed solutions could be well predicated using the XDLVO theory, and the higher the interfacial energy, the faster the flux decline was found for both adhesion and cohesion stages. The findings improve the understanding of FO membrane fouling mechanism by microalgae, indicating the selection of algae species for FO processes.

Fluorescence-Based Detection of Cholesterol Using Inclusion Complex of Hydroxypropyl-β-Cyclodextrin and l-Tryptophan as the Fluorescence Probe

The study is inspired by the fact that intravenous administration of 2-hydroxypropyl-beta-cyclodextrins (HP-β-CD) in rats leads to a rapid decrease in plasma cholesterol levels. Further, HP-β-CD being more water soluble than native β-CD, HP-β-CD forms soluble complex with cholesterol and higher affinity of cholesterol towards HP-β-CD than native β-CD leads to increase sensitivity. Hence, present work reports potential use of HP-β-CD as a chemosensor to detect cholesterol aided with l-tryptophan (l-Trp) as a fluorescence probe. The purpose of the study is to develop fast, cost-effective, and high throughput fluorescence-based chemosensor as convenient point-of-care diagnostic method for cholesterol detection. The host-guest interaction of l-Trp with HP-β-CD was elaborately studied using characterization techniques such as FT-IR, NMR, and DSC. Time and concentration dependent interactions were studied to determine the stoichiometry of molecular inclusion complexes of HP-β-CD with l-Trp. Further, the inclusion complex of HP-β-CD with l-tryptophan is explored to detect cholesterol based on the competitive displacement phenomenon and further explored for detecting different concentrations of cholesterol. Fluorescence spectroscopic data revealed that HP-β-CD served as a quencher for l-Trp. Also, promising results of the displacement assay proved that the fluorescence of l-Trp was quenched by HP-β-CD followed by increase in fluorescence signals in quantitative relation with cholesterol as it replaces l-Trp from the HP-β-CD host. The present investigation is a proof-of-concept that proves the potential of HP-β-CD with l-Trp as a novel fluorescence–based technique for cholesterol detection which is developed using competitive host–guest interaction.

Sintering of MAX-phase materials by spark plasma and other methods

This review focuses on the comparison of the spark plasma sintering (SPS) with other fabrication methods of MAX-phase materials. In the view of optimizing properties for prospective applications, we summarized different routes to synthesize and sinter bulk/powder MAX-phases with various microstructures, discussed the phase composition of MAX-phases obtained by SPS and other methods. In the article, we introduced the experimental features of various sintering methods and carried out the comparative analysis of “competition phenomenon” between the SPSed MAX-phases and MAX-phases prepared by other technologies. We referred to relevant reports and reviews in which one can acquire a comprehensive understanding of sintering kinetics, sintering thermodynamics, grain growth kinetics, and densification mechanisms. Furthermore, the influence of the sintering routes on the properties of the MAX-phases was discussed paying emphasis on the mechanical properties.

A comparative study of the crystallinity of polyetheretherketone by using density, DSC, XRD, and Raman spectroscopy techniques

A comparative study of the crystallinity of Polyetheretherketone by using density, DSC, XRD, and Raman spectroscopy techniques.In this work, the microstructure of Polyetheretherketone is first analyzed with usual techniques such as density, Differential Scanning Calorimetry, X-ray Diffraction, and secondly, compared with Raman Spectroscopy. Assessing the degree of crystallinity of PEEK is challenging because of the different interpretation of the crystallinity according to each technique. The density measurement gives the highest most trusted absolute uncertainty for the degree of crystallinity, around 4%, compared to the other techniques. The Differential Scanning Calorimetry, usually used by the polymer community, overestimates up to 18% the degree of crystallinity due to a competitive phenomenon between crystallization and melting of PEEK over the same temperature range, and a fast crystallization. When Analyzing the X-ray Diffraction data, the degree of crystallinity is underestimated up to 11% as a consequence of the broad amorphous halo. Lastly, our investigation proves that Raman microspectroscopy is appropriate to determine the local crystallinity on the sample surface and compares 18 indicators in the same study. The 1651 cm-1 band shift has the highest correlation coefficient of 0.92 with the degree of crystallinity determined by density. This work attempts to correlate the results of degree of crystallinity of PEEK obtained by these four techniques in order to establish the best evaluation of this fundamental property for numerous applications.

An experiment study of vortex induced vibration of a steel catenary riser under steady current

The vortex induced vibration (VIV) of marine risers has been investigated by many researchers in experimental studies of a straight flexible riser model as well as a rigid cylinder to reveal the dynamic response characteristic and the mechanics behind it. However, due to the limitation of experimental apparatus, very few studies are about the VIV of a steel catenary riser (SCR) which is with a complex geometry. To investigate the VIV features and to further develop the corresponding numerical predictions of a SCR under steady current, a large-scale model test of a SCR was towed in an ocean basin at various speeds. Fiber Bragg grating strain sensors are instrumented on the riser model to measure both in-plane and out-of-plane responses. The characteristics of oscillating amplitude and dominating frequency response, the phenomenon of mode competition and travelling wave and the fatigue damage of the steel catenary riser in inline and cross-flow direction under steady current are analyzed.

A non-homogeneous Markov early epidemic growth dynamics model. Application to the SARS-CoV-2 pandemic.

This work introduces a new markovian stochastic model that can be described as a non-homogeneous Pure Birth process. We propose a functional form of birth rate that depends on the number of individuals in the population and on the elapsed time, allowing us to model a contagion effect. Thus, we model the early stages of an epidemic. The number of individuals then becomes the infectious cases and the birth rate becomes the incidence rate. We obtain this way a process that depends on two competitive phenomena, infection and immunization. Variations in those rates allow us to monitor how effective the actions taken by government and health organizations are. From our model, three useful indicators for the epidemic evolution over time are obtained: the immunization rate, the infection/immunization ratio and the mean time between infections (MTBI). The proposed model allows either positive or negative concavities for the mean value curve, provided the infection/immunization ratio is either greater or less than one. We apply this model to the present SARS-CoV-2 pandemic still in its early growth stage in Latin American countries. As it is shown, the model accomplishes a good fit for the real number of both positive cases and deaths. We analyze the evolution of the three indicators for several countries and perform a comparative study between them. Important conclusions are obtained from this analysis.

Surfactant changes lead adsorption behaviors and mechanisms on microplastics

The impact of surfactant addition on the adsorption performance of lead ion (Pb2+) as a typical heavy metal ion on three microplastics was investigated. The types of microplastics (polyethylene (PE), polypropylene (PP) and polymethylmethacrylate (PMMA)) and surfactants (triton X-100 (TX-100), 1-hexadecylpyridinium bromide (HDPB), and sodium dodecyl benzenesulfonate (SDBS)), adsorption time, concentration of Pb2+, and coexisting ions was systematically investigated, and the characteristics of adsorption of Pb2+ by microplastics were analyzed. The experimental results showed that the adsorption capacity of Pb2+ on three micropalstics was different. The adsorption capacity of Pb2+ on the three microplastics without surfactants was: 4.21 (PMMA) > 2.01 (PE) > 1.57 mg g−1 (PP). The addition of surfactants resulted in a higher hydrophilicity of microplastics, and obviously improved the adsorption ability of microplastics for lead ions. SDBS can significantly enhance the adsorption of Pb2+ on three microplastics compared with other two surfactants (TX100 and HDPB). The highest adsorption capacity of Pb2+ on the three microplastics with addition of SDBS solution was: 7.87 (PMMA) > 7.20 (PE) > 7.02 mg g−1 (PP). With the increase of adsorption time and Pb2+ concentration, the adsorption efficiency of microplastics for Pb2+ first increased and then decreased. The pH of solution had a great influence on the adsorption of Pb2+ by microplastics. The results of coexisting ion experiments demonstrated that when lead ion and copper ion coexist, the two ions have competitive adsorption phenomenon on PP. This research explored the adsorption characteristics of lead ions by microplastics with addition of surfactants, which can provide theoretical basis for further study of heavy metal enrichment and environmental behavior of microplastics in the environment.

Energy Finance Development Research of Maritime Silk Road

Jin, J.Y.; Zhang, N.; Li, F.; Chuan, M., and Yang, Y.S., 2020. Energy finance development research of Maritime Silk Road. In: Qiu, Y.; Zhu, H., and Fang, X. (eds.), Current Advancements in Marine and Coastal Research for Technological and Sociological Applications. Journal of Coastal Research, Special Issue No. 107, pp. 443-448. Coconut Creek (Florida), ISSN 0749-0208.Maritime Silk Road first proposed by China is rich in energy storage, and it is also the growth point of developing energy finance, this paper concludes that Sichuan Province plays a leading role in our country's energy finance development, and that different places have dramatically diverse energy finance development. The energy industry is not coordinated with financial economy and the development of supporting industries. As determined by factor analysis method by building an assessment index of energy finance development, there exists a phenomenon of homogeneous competition. The gravitation model clearly shows the influence and competitiveness between different provinces and the advantages and disadvantages of each province in energy finance development, thus providing direction for future development.

Multi-scale modeling of liquid-metal cooling directional solidification and solidification behavior of nickel-based superalloy casting

Liquid-metal cooling (LMC) process can offer refinement of microstructure and reduce defects due to the increased cooling rate from enhanced heat extraction, and thus an understanding of solidification behavior in nickel-based superalloy casting during LMC process is essential for improving mechanical performance of single crystal (SC) castings. In this effort, an integrated heat transfer model coupling meso grain structure and micro dendrite is developed to predict the temperature distribution and microstructure evolution in LMC process. An interpolation algorithm is used to deal with the macro-micro grids coupling issues. The algorithm of cells capture is also modified, and a deterministic cellular automaton (DCA) model is proposed to describe neighborhood cell tracking. In addition, solute distribution is also considered to describe the dendrite growth. Temperature measuring, EBSD, OM and SEM experiments are implemented to verify the proposed model, and the experiment results agree well with the simulation results. Several simulations are performed with a range of withdrawal rates, and the results indicate that 12 mm·min-1 is suitable for LMC process in this work, which can result in a fairly narrow and flat mushy zone and correspondingly exhibited fairly straight grains. The mushy zone length is about 4.8 mm in the steady state and the average deviation angle of grains is about 13.9° at the height 90 mm from the casting base under 12 mm·min-1 withdrawal process. The competitive phenomenon of dendrites at different withdrawal rates is also observed, which has a great relevant to the temperature fluctuation.

A new (MOM) approach of the (OLPT) model application to the (AC) conductivity in ZnS chalcogenide material

In this work, we have proposed a theoretical investigation of the complicated Overlapping Large Polaron Tunneling (OLPT) conduction mechanism. In fact, in previous works, some approximations have been made in the aim of adopting the (OLPT) model to the experimental data. These approximations are not convincing and lead to reviewing the (OLPT) model.Thus, in order to avoid these disagreements between experimental and theoretical results, we have proposed a new “methodology” which has allowed us to explore in depth this mechanism of conduction not well investigated. Due to the existence of two variables: temperature and frequency, a fundamental step is to adopt a new approach to fit theoretical parameters to experimental data: the Advanced Second order Fitting (ASF). This approach allowed us to discover the existence of relevant term appearing in the expression of the trapping potential. The corresponding physical interpretation reveals an original and unexpected behavior. The modified (OLPT) model (MOM) proves in a categorical way the validity of certain approximations used without being adequately justified by the (OLPT) model. (MOM) highlights two competitive and spectacular phenomena: the thermal effect and the resonance phenomena. In this work, we have considered the example of ZnS: a chalcogenide presenting the (OLPT) conduction mechanism.

I am Gonna Sue... Again? Relationship Between CEO Characteristics and Firm Litigiousness

This study investigates the process in which CEO characteristics affect firms’ litigation behaviors from the upper echelons perspective. Inter-firm litigation has been pronounced as major competitive phenomena of late despite the overall atmosphere of emphasizing cooperation among businesses. By combining regulatory focus theory and organizational identification theory within the awareness-motivation-capabilities (AMC) framework of competitive dynamics, it seeks to explain how CEOs’ cognitive and emotional process can determine firms’ actions and reactions in inter-firm litigation. The empirical test finds that CEOs with high promotion focus show a lower propensity for legal actions, while CEOs with high prevention focus do not manifest a clear tendency. On the other hand, it is demonstrated that CEOs’ organizational identification is a key driving force in suing competitors, and the mitigating interaction effect between promotion focus and organizational identification is also suggested.

Investigations on SHG properties of LiNbO3/PMMA nanocomposites

An organic–inorganic nanocomposite (LN/PMMA) was prepared using nearly stoichiometric lithium niobate (LiNbO3; LN) nanoparticles dispersed homogeneously into a polymer matrix, poly(methyl methacrylate) (PMMA). This composite is having anisotropic LN nanocrystals, oriented randomly in an isotropic host matrix of PMMA. So far, to the best of our knowledge, different nonlinear optical (NLO) properties have been studied for organic–inorganic nanocomposites in thin film and waveguide form, the thickness of which was in micron and submicron order. In this article, for the first time, we have presented SHG properties of thick LN/PMMA nanocomposites of thickness, 0.1 mm and above. LN/PMMA nanocomposite samples of different thickness and different concentrations of LN nanoparticles were fabricated. The attenuation coefficients of these samples, measured at laser wavelengths of 1064 nm and 532 nm, show a deviation from Beer-Lambert law. In the LN/PMMA nanocomposite, the effect of the randomly oriented LN nanoparticles on second harmonic generation (SHG) has been studied as a function of (a) input pulse energy of the fundamental laser (1064 nm), (b) LN nanoparticle concentration and (c) the sample thickness. The net effect was found to be the result of two competitive phenomena; harmonic generation and different losses from LN nanoparticles. Thermal effects at high input pulse energy also play important role in second harmonic generation. Through these studies, one can get an idea about the collective behavior of LN nanoparticles, particularly effect on their linear and nonlinear optical properties, and how they can be dispersed in isotropic host matrices (to different concentration levels) to achieve the desired NLO effect.

Elaboration of a model of Pavlovian learning and performance: HeiDI.

The model elaborated here adapts the influential pooled error term, first described by Wagner and Rescorla (Rescorla & Wagner, 1972; Wagner & Rescorla, 1972), to govern the formation of reciprocal associations between any pair of stimuli that are presented on a given trial. In the context of Pavlovian conditioning, these stimuli include various conditioned and unconditioned stimuli. This elaboration enables the model to deal with cue competition phenomena, including the relative validity effect, and evidence implicating separate error terms and attentional processes in association formation. The model also includes a performance rule, which provides a natural basis for (individual) variation in the strength and nature of conditioned behaviors that are observed in Pavlovian conditioning procedures. The new model thereby begins to address theoretical and empirical issues that were apparent when the Rescorla-Wagner model was first described, together with research inspired by the model over the ensuing 50 years. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Effectiveness of alien brown troutSalmo truttaL. removal activities for the native trout conservation in Mediterranean streams

In Italian freshwaters the introgressive hybridization with the alien Atlantic trout represents the principal threat to the native endangered Mediterranean trout. The aim of the research was to test the effectiveness of alien trout removal activities carried out by electrofishing in four streams in Central Italy. The four sites were chosen on the basis of the severe genetic introgression level of the trout populations. The removal activities were carried out from December 2014 to July 2017, for a total of 10 eradication campaigns in each site. During each field activity, five environmental parameters (flow rate, conductivity, average depth, average width, accessibility) were collected, since they could influence both the effectiveness of the electrofishing and the biological characteristics of the fish populations. A total of over 22,000 alien trout accounting for a biomass of over 700 kg were removed from the removal sites. For each site, a progressive drastic decrease over time in density and standing crop values was observed. Removal rates ranged from 94.22% to 100.00% for density, and from 96.57% to 100.00% for standing crop. The correlation analysis showed an inverse significant relationship between catchability and populations abundance, confirming that low density populations are more suitable to removal efforts. The progressive removal of specimens improved the catchability over time, indicating that even the largest populations could be eradicated, providing the necessary number of steps in a fishing season. The improved body condition and the greater growth rates observed during the eradication period, in low abundance conditions, seemed to confirm the key role that intraspecific competition and density-dependent phenomena play in the Apennine trout population dynamics. The results obtained in the present research provided evidence that electrofishing removal could be an effective management tool for the Mediterranean trout conservation, especially in watercourses of modest dimensions in terms of flow rates, width and depth.

Fully nonlinear mode competition in magnetised Taylor–Couette flow

We study the nonlinear mode competition of various spiral instabilities in magnetised Taylor-Couette flow. The resulting finite-amplitude mixed-mode solution branches are tracked using the annular-parallelogram periodic domain approach developed by Deguchi & Altmeyer (2013). Mode competition phenomena are studied in both the anti-cyclonic and cyclonic Rayleigh-stable regimes. In the anti-cyclonic sub-rotation regime, with the inner cylinder rotating faster than the outer, Hollerbach, Teeluck & Rudiger (2010) found competing axisymmetric and non-axisymmetric magneto-rotational linearly unstable modes within the parameter range where experimental investigation is feasible. Here we confirm the existence of mode competition and compute the nonlinear mixed-mode solutions that result from it. In the cyclonic super-rotating regime, with the inner cylinder rotating slower than the outer, Deguchi (2017) recently found a non-axisymmetric purely hydrodynamic linear instability that coexists with the non-axisymmetric magneto-rotational instability discovered a little earlier by Rudiger, Schultz, Gellert & Stefani (2016). We show that nonlinear interactions of these instabilities give rise to rich pattern-formation phenomena leading to drastic angular momentum transport enhancement/reduction.

Highly permeable innovative PDMS coated polyethersulfone membranes embedded with activated carbon for gas separation

Innovative asymmetric polyethersulfone (PES) membranes embedded with activated carbon (AC) were synthesized and then surface coated with thin PDMS layer. The membranes were then tested with advanced analytical techniques like FTIR, TGA, SEM and EDX analysis. Thereafter, the membranes were tested for gas permeation analysis with following five gases: carbon dioxide, hydrogen, nitrogen, helium and methane. The effects of embedding AC and feed gas pressure on gas permeation properties were also examined. The permeance of all the gases improved with the embedding of AC in the membrane without much decreasing their ideal selectivity while PDMS coating enhanced the ideal selectivity at the expense of decreasing permeance of all the gases. It was found that 30 wt. % AC embedded PDMS coated PES membrane, having thickness of 80 μm, exhibited the best gas permeation properties for following five pair of gases CO2/N2, CO2/CH4, H2/N2, He/N2 and He/CH4 at 25 °C and 20 bar. The best performing membrane was also tested for long term stability by exposing it with each gas for 96 h. It was also found that the performance of 30 wt % AC embedded membrane, surpassed the 2008 Robeson trade off line for all pair of gases except for CO2/CH4 for which it nearly touched this line. Finally, PDMS coated membranes were also tested with CO2/CH4 (50:50) mixture at high pressure and found that mixed gas permeation properties are considerably lesser than pure gas permeation properties due to possibility of competitive sorption phenomenon between the gases.

Dynamics of Changes in the Level of Competitiveness of Manufacturing in Poland

The development of modern economies is inseparably connected with the phenomenon of competition and competitiveness of business entities. Issues in the field of competitiveness of economies, sectors and enterprises have become the subject of intensive analysis worldwide. In Poland, there is also an urgent need to conduct research on various aspects of competitiveness which should thoroughly diagnose the situation in this respect and indicate the development of adequate instruments of economic policy stimulating the growth of competitiveness. This article is a response to this need. The main aim of the study is to assess and compare selected aspects of competitiveness of enterprises from manufacturing divisions. Therefore, the analysis covered manufacturing enterprises (Section C) at the two-digit level of aggregation, i.e. at the level of divisions in this Section. To assess competitiveness in the years 2010-2016, the following measures were used: export/import ratio, intra-industrial trade index (IIT), sold production, labour productivity, and total factor productivity (TFP). The research proceedings were based on data published by the Central Statistical Office (Statistics Poland).

Clarifying the roles of hydrothermal treatment and silica addition to synthesize TiO2-based nanocomposites with high photocatalytic performance

In this work we investigated the effect of hydrothermal treatment and silica addition on the structure and photocatalytic performance of synthesized TiO2-based nanocomposites. These materials were prepared by combining sol–gel process and hydrothermal treatment, and no templates or surfactants were used in these syntheses. The optimal synthesis conditions were investigated based on the variation of the preparation parameters. Anatase TiO2 crystals were synthesized without the need of a hydrothermal treatment, but this process appeared necessary to form an anatase phase with better structural quality and high photoactivity. The heat treatment step induced competitive phenomena toward the TiO2 structural properties and its photodegradation activity, but it proved to be advantageous as long as the pore structure, anatase phase, and high specific surface area were maintained. The addition of silica was then justified, aiming to stabilize the crystalline structure of TiO2 upon heat treatment. The ideal molar ratio of Si/(Si + Ti) was 0.2 for samples heat-treated at either 500 or 700 °C. The high photocatalytic efficiency of the synthesized nanocomposites is due to the combined effect of the photoactivity of TiO2 and adsorption capacity of SiO2. When compared with a commercial TiO2 sample (Degussa Evonik P25), increasing the catalyst loading proved to greatly enhance the performance of the synthesized nanocomposite, whereas the commercial one did not follow the same trend.

The effect of heavy metal ions hydration on their sorption by a mesoporous titanium phosphate ion-exchanger

The sorption properties of a titanium phosphate ion-exchanger (Na-TiOP) towards Pb2+ Cd2+, Zn2+ and Co2+ have been investigated. The sorbent displays the highest Pb2+ uptake (1.95 mmol g–1) among other TiP ion-exchangers. To explore the ability of the titanium phosphate sorbent toward heavy metal ions the sorption equilibrium and kinetics parameters have been studied. To gain insight into some mechanisms of interactions between the sorbent and solute the radius and dehydration degree of the adsorbed ions have been calculated. The sorbent shows fast kinetics, the metal removal efficiency after 5−10 min of the sorption process is estimated to be 90–95 % for all metal ions studied. The equilibrium reached within 15−60 min, and the experimental data were best fitted to the pseudo-second-order kinetic model. Thermodynamic parameters of the sorption process were calculated, and it has been shown that the main factor determining the endothermic nature of the process is the partial destruction of the hydration shell of the sorbed ions. Titanium phosphate effectively removes metal ions from multi-component model and real wastewater solutions, resulting in the sorption capacity of heavy metal ions 2.03 mmol g–1. It makes this material an advanced sorbent for the selective isolation of toxic metals cations from sewage water. A competitive sorption phenomenon in favor of Pb2+ on titanium phosphate is shown for all studied complex solutions. The selectivity can be represented as Pb2+ > Cd2+ > Zn2+ > Co2+.