Covalent Assembly of Penicillin Acylase in Mesoporous Silica Based on Macromolecular Crowding Theory

To improve the covalent immobilization of penicillin acylase （PA）, macromolecular crowding theory was applied to its immobilization. Influence of mass ratio of enzyme to the silica, as well as, activation time with glutaraldehyde on the activity of assembled PA, was studied. In the mesopores, the effect of fl-cyclodextrin （β-CD） on the immobilization of the enzyme was also investigated. It was remarkable that the coupled yield and relative activity reached 99.5% and 92.3%, respectively, when penicillin acylase assembled covalently in the mesopores. The results here indicate that mimicked macromolecule crowding could significantly ameliorate the performance of covalently immobilized PA.

GLOBAL OPTIMIZATION OF PUMP CONFIGURATION PROBLEM USING EXTENDED CROWDING GENETIC ALGORITHM

An extended crowding genetic algorithm (ECGA) is introduced for solvingoptimal pump configuration problem, which was presented by T. Westerlund in 1994. This problem hasbeen found to be non-convex, and the objective function contained several local optima and globaloptimality could not be ensured by all the traditional MINLP optimization method. The concepts ofspecies conserving and composite encoding are introduced to crowding genetic algorithm (CGA) formaintain the diversity of population more effectively and coping with the continuous and/or discretevariables in MINLP problem. The solution of three-levels pump configuration got from DICOPT++software (OA algorithm) is also given. By comparing with the solutions obtained from DICOPT++, ECPmethod, and MIN-MIN method, the ECGA algorithm proved to be very effective in finding the globaloptimal solution of multi-levels pump configuration via using the problem-specific information.

PERSISTENCE AND THE GLOBAL DYNAMICS OF THE POSITIVE SOLUTIONS FOR A RATIODEPENDENT PREDATOR-PREY SYSTEM WITH A CROWDING TERM IN THE PREY EQUATION

This paper deals with the global dynamical behaviors of the positive solutions for a parabolic type ratio-dependent predator-prey system with a crowding term in the prey equation, where it is assumed that the coefficient of the functional response is less than the coefficient of the intrinsic growth rates of the prey species. We demonstrated some special dynamical behaviors of the positive solutions of this system which the persistence of the coexistence of two species can be obtained when the crowding region in the prey equation only is designed suitably. Furthermore, we can obtain that under some conditions, the unique positive steady state solution of the system is globally asymptotically stable.

Spatial Modeling of Residential Crowding in Alexandria Governorate, Egypt: A Geographically Weighted Regression (GWR) Technique

Despite growing research for residential crowding effects on housing market and public health perspectives, relatively little attention has been paid to explore and model spatial patterns of residential crowding over space. This paper focuses upon analyzing the spatial relationships between residential crowding and socio-demographic variables in Alexandria neighborhoods, Egypt. Global and local geo-statistical techniques were employed within GIS-based platform to identify spatial?variations of residential crowding determinates. The global ordinary least squares (OLS) model?assumes homogeneity of relationships between response variable and explanatory variables?across the study area. Consequently, it fails to account for heterogeneity of spatial relationships. Local model known as a geographically weighted regression (GWR) was also employed using the same?response variable and explanatory variables to capture spatial non-stationary of residential?crowding. A comparison of the outputs of both models indicated that OLS explained 74 percent of?residential crowding variations while GWR model explained 79 percent. The GWR improvedstrength of the model and provided a better goodness of fit than OLS. In addition, the findings of this analysis revealed that residential crowding was significantly associated with different structural measures particularly social characteristics of household such as higher education and illiteracy. Similarly, population size of neighborhood and number of dwelling rooms were found to have direct impacts on residential crowding rate. The spatial relationship of these measures distinctly varies over the study area.

Transcriptomic Profiling of the Immune Response to Crowding Stress in Juvenile Turbot (Scophthalmus maximus)

In this study,juvenile turbot Scophthalmus maximus were vaccinated with attenuated Edwardsiella tarda(EIBAV1)and reared at two different densities,low density(LD),(5.25±0.02)kg m−2,as control group and high density(HD),(20.53±0.05)kg m−2,as experimental group.Only density was considered as the variable.Five weeks after vaccination,the transcriptomes of spleen and head kidney from the turbot in two groups were analyzed with RNA-Seq technology.A total of 447 million reads were assembled into 41136 genes with an average length of 1274 bp and a N50 size of 2295 bp.A comparison of gene expression between HD and LD groups revealed 1155 differentially expressed genes(DEGs).Enrichment and pathway analysis of the 10 immune-related DEGs showed the centrality of toll-like receptor signaling pathway,cytosolic DNA-sensing pathway and platelet activation in the host immune responses.The 5 overexpressed inflammatory cytokines and 5 downregulated signal-regulated cytokines genes are covered by these immune-related DEGs.It was inferred that cells suffer damage and the immune response is restrained in turbot under crowding stress.

EXISTENCE AND UNIQUENESS OF THE POSITIVE STEADY STATE SOLUTION FOR A LOTKA-VOLTERRA PREDATOR-PREY MODEL WITH A CROWDING TERM

This paper deals with a Lotka-Volterra predator-prey model with a crowding term in the predator equation.We obtain a critical value λ1^D(Ω0),and demonstrate that the existence of the predator inΩ0 only depends on the relationship of the growth rateμof the predator and λ1^D(Ω0),not on the prey.Furthermore,whenμ<λ1^D(Ω0),we obtain the existence and uniqueness of its positive steady state solution,while whenμ≥λ1^D(Ω0),the predator and the prey cannot coexist inΩ0.Our results show that the coexistence of the prey and the predator is sensitive to the size of the crowding regionΩ0,which is different from that of the classical Lotka-Volterra predator-prey model.

Niching method using clustering crowding

This study analyzes drift phenomena of deterministic crowding and probabilistic crowding by using equivalence class model and expectation proportion equations. It is proved that the replacement errors of deterministic crowding cause the population converging to a single individual, thus resulting in premature stagnation or losing optional optima. And probabilistic crowding can maintain equilibrium multiple subpopulations as the population size is adequate large. An improved niching method using clustering crowding is proposed. By analyzing topology of fitness landscape using hill valley function and extending the search space for similarity analysis, clustering crowding determines the locality of search space more accurately, thus greatly decreasing replacement errors of crowding. The integration of deterministic and probabilistic replacement increases the capacity of both parallel local hill climbing and maintaining multiple subpopulations. The experimental results optimizing various multimodal functions show that,the performances of clustering crowding, such as the number of effective peaks maintained, average peak ratio and global optimum ratio are uniformly superior to those of the evolutionary algorithms using fitness sharing, simple deterministic crowding and probabilistic crowding.

Changes in the crown angulation and dental arch widths after nonextraction orthodontic treatment: Model analysis of mild crowding with high canines

This study was undertaken to examine which factors contributed to the correction of crowding in two patients who underwent nonextraction orthodontic treatment. A study model analysis was conducted to determine the effects of the orthodontic treatment for crowding with high canines on crown angulation and dental arch width in two patients. The results showed that the crown angulation was significantly increased, indicating distal tipping in the maxillary dental arch. This tendency was most commonly observed in the premolars among the lateral teeth. With respect to the dental arch width, the largest change was evident in the first molar and first premolar regions in cases 1 and 2, respectively. On the basis of these results, up-righting of mesially tipped lateral teeth and expansion of narrow dental arches could prove to be the keys to the success of space regaining or correction of high canines and mild crowding.

A Potential Model for Detecting Crowding-induced Epithelial Cell and Cancer Cell Extrusion

Overcrowding and cell deformation lead to the shedding of apoptotic and live cells to maintain homeostasis in the epithelium. Recent studies have attempted to explain the effect of extrusion on epithelial homeostasis and tumor metastasis, but lack the requisite quantitative models for testing extrusion. Here, we designed a petri dish inversion model to detect the extrusion ability of both normal epithelial cells and epithelial cancer cells. Firstly, we found cell extrusion was observed in both normal epithelial cells (LO2 cells) and cancer cells;in confluent LO2 cell culture, certain cells were surrounded by their neighbors, suffered "collective attack", and were then made round in shape. Green fluorescent protein (GFP)-labeled cancer cells were also found to be squeezed by normal LO2 cells. Using the petri dish inversion model, we quantified the number of extrusion cells, and demonstrated that the ability of cancer cell extrusion was related to the metastatic potential of cancer cell lines. Our findings provide a novel model to detect crowdinginduced epithelial cell and cancer cell extrusion. This novel model provides a quantitative method for research into apoptotic and cancer cell extrusion, particularly in human hepatocellular carcinoma.

Effect of Crowding in Metro Carriages on Travelers’ Disutility: An Evidence from Guangzhou Metro

Overcrowding has become a non negligible issue for metros in China.This paper analyzes the impact of crowding in metro carriages on people’s travel behaviors based on the stated preference survey data from college students and full time workers in Guangzhou.The data were analyzed by using the constant value per trip model and the travel time multiplier model with the multinomial logit modeling technique.Results show that there is a significant impact of crowding in metro carriages on passengers’welfare.The relationship between the disutility of crowding and the standee density is not linear.Commuters do not care much about crowding in the metro,whereas non commuters and college students pay special attention to crowding in metro carriages,especially when the carriage is crowded.This paper presents new findings of the impact of demographic characteristics on the evaluation of crowding in metro carriages in developing countries.

Phase transition of DNA compaction in confined space: Effects of macromolecular crowding are dominant

With a view of detecting the effects of macromolecular crowding on the phase transition of DNA compaction confined in spherical space,Monte Carlo simulations of DNA compaction in free space,in confined spherical space without crowders and in confined spherical space with crowders were performed separately.The simulation results indicate that macromolecular crowding effects on DNA compaction are dominant over the roles of multivalent counterions.In addition,effects of temperature on the phase transition of DNA compaction have been identified in confined spherical space with different radii.In confined spherical space without crowders,the temperature corresponding to phase transition depends on the radius of the confined spherical space linearly.In contrast,with the addition of crowders to the confined spherical space,effects of temperature on the phase transition of DNA compaction become insignificant,whereas the phase transition at different temperatures strongly depends on the size of crowder,and the critical volume fraction of crowders pertains to the diameter of crowder linearly.

A complete small-signal HBT model including AC current crowding effect

An improved small-signal equivalent circuit of HBT concerning the AC current crowding effect is proposed in this paper. AC current crowding effect is modeled as a parallel RC circuit composed of Cbi and Rbi, with distributed base-collector junction capacitance also taken into account. The intrinsic portion is taken as a whole and extracted directly from the measured Sparameters in the whole frequency range of operation without any special test structures. An HBT device with a 2 × 20 μm^(2) emitter-area under three different biases were used to demonstrate the extraction and verify the accuracy of the equivalent circuit.

SOEs urged not to profit by crowding out private economy

Hu Deping,68,is the oldest son of Hu Yaobang,a late Party secretary general. His name has recently appeared in the press not because of his father’s reputation but for his own

Molecular crowding electrolytes for stabilizing Zn metal anode in rechargeable aqueous batteries

A solid electrolyte interphase(SEI)with a robust mechanical property and a high ionic conductivity is imperative for high-performance zinc metal batteries.However,it is difficult to form such a SEI directly from an electrolyte.In this work,a molecular crowding effect is based on the introduction of Zn(OTF)_(2)and Zn(ClO_(4))_(2)to 2 mol/L ZnSO_(4)electrolytes.Simulations and experiments indicate that the Zn(OTF)_(2)and Zn(ClO_(4))_(2)not only create a molecularly crowded electrolyte environment to promote the interaction of Zn^(2+)and OTF^(-),but also participate in the reduction to construct a robust and high ionic-conductive SEI,thus promoting metal zinc deposition to the(002)crystal surface.With this molecular crowding electrolyte,a high current density of 1 mA/cm^(2)can be obtained by assembling symmetric batteries with Zn as the anode for over 1000 h.And in a temperature environment of-10℃,a current density of 1 mA/cm^(2)can be obtained by assembling symmetric batteries with Zn for over 200 h.Zn//Bi_(2)S_(3)/VS4@C cells achieve a CE rate of up to 99.81%over 1000 cycles.Hence,the utilization of a molecular crowding electrolyte is deemed a highly effective approach to fabricating a sophisticated SEI for a zinc anode.

A Multi-strategy Improved Snake Optimizer Assisted with Population Crowding Analysis for Engineering Design Problems

Snake Optimizer(SO)is a novel Meta-heuristic Algorithm(MA)inspired by the mating behaviour of snakes,which has achieved success in global numerical optimization problems and practical engineering applications.However,it also has certain drawbacks for the exploration stage and the egg hatch process,resulting in slow convergence speed and inferior solution quality.To address the above issues,a novel multi-strategy improved SO(MISO)with the assistance of population crowding analysis is proposed in this article.In the algorithm,a novel multi-strategy operator is designed for the exploration stage,which not only focuses on using the information of better performing individuals to improve the quality of solution,but also focuses on maintaining population diversity.To boost the efficiency of the egg hatch process,the multi-strategy egg hatch process is proposed to regenerate individuals according to the results of the population crowding analysis.In addition,a local search method is employed to further enhance the convergence speed and the local search capability.MISO is first compared with three sets of algorithms in the CEC2020 benchmark functions,including SO with its two recently discussed variants,ten advanced MAs,and six powerful CEC competition algorithms.The performance of MISO is then verified on five practical engineering design problems.The experimental results show that MISO provides a promising performance for the above optimization cases in terms of convergence speed and solution quality.

Characterization of the current crowding effect on chip surface using a quantum wide-field microscope

We characterize the current crowding effect for microwave radiation on a chip surface based on a quantum wide-field microscope combining a wide-field reconstruction technique. A swept microwave signal with the power of 0–30 d Bm is supplied to a dumbbell-shaped microstrip antenna, and the significant differences in microwave magnetic-field amplitudes attributed to the current crowding effect are experimentally observed in a 2.20 mm ×1.22 mm imaging area. The normalized microwave magnetic-field amplitude along the horizontal geometrical center of the image area further demonstrates the feasibility of the characterization of the current crowding effect. The experiments indicate the proposal can be qualified for the characterization of the anomalous area of the radio-frequency chip surface.

The transcriptomic signature of responses to larval crowding in Drosophila melanogaster

Intraspecific competition at the larval stage is an important ecological factor affecting life-history,adaptation and evolutionary trajectory in holometabolous insects.However,the molecular pathways underpinning these ecological processes are poorly characterized.We reared Drosophila melanogaster at three egg densities(5,60,and 300 eggs/mL)and sequenced the transcriptomes of pooled third-instar larvae.We also examined emergence time,egg-to-adult viability,adult mass,and adult sex-ratio at each density.Medium crowding had minor detrimental effects on adult phenotypes compared to low density and yielded 24 differentially expressed genes(DEGs),including several chitinase enzymes.In contrast,high crowding had substantial detrimental effects on adult phenotypes and yielded 2107 DEGs.Among these,upregulated gene sets were enriched in sugar,steroid and amino acid metabolism as well as DNA replication pathways,whereas downregulated gene sets were enriched in ABC transporters,taurine,Toll/Imd signaling,and P450 xenobiotics metabolism pathways.Overall,our findings show that larval crowding has a large consistent effect on several molecular pathways(i.e.,core responses)with few pathways displaying density-specific regulation(i.e.,idiosyncratic responses).This provides important insights into how holometabolous insects respond to intraspecific competition during development.

Multi-objective particle swarm optimization algorithm using Cauchy mutation and improved crowding distance

Purpose-Multi-objective is a complex problem that appears in real life while these objectives are conflicting.The swarm intelligence algorithm is often used to solve such multi-objective problems.Due to its strong search ability and convergence ability,particle swarm optimization algorithm is proposed,and the multi-objective particle swarm optimization algorithm is used to solve multi-objective optimization problems.However,the particles of particle swarm optimization algorithm are easy to fall into local optimization because of their fast convergence.Uneven distribution and poor diversity are the two key drawbacks of the Pareto front of multi-objective particle swarm optimization algorithm.Therefore,this paper aims to propose an improved multi-objective particle swarm optimization algorithm using adaptive Cauchy mutation and improved crowding distance.Design/methodology/approach-In this paper,the proposed algorithm uses adaptive Cauchy mutation and improved crowding distance to perturb the particles in the population in a dynamic way in order to help the particles trapped in the local optimization jump out of it which improves the convergence performance consequently.Findings-In order to solve the problems of uneven distribution and poor diversity in the Pareto front of multi-objective particle swarm optimization algorithm,this paper uses adaptive Cauchy mutation and improved crowding distance to help the particles trapped in the local optimization jump out of the local optimization.Experimental results show that the proposed algorithm has obvious advantages in convergence performance for nine benchmark functions compared with other multi-objective optimization algorithms.Originality/value-In order to help the particles trapped in the local optimization jump out of the local optimization which improves the convergence performance consequently,this paper proposes an improved multi-objective particle swarm optimization algorithm using adaptive Cauchy mutation and improved crowding distance.

New insights into the effect of molecular crowding environment induced by dimethyl sulfoxide on the conformation and stability of G-quadruplex

Various structures of G-quadruplex in biosystems play an important role in different diseases and are often regulated by a variety of molecular crowding environments induced by internal and even external factors(e.g.,a solvent).Dimethyl sulfoxide(DMSO),a universal solvent,has been widely used in biological studies and for drug therapy,but little is known regarding its effect on G-quadruplex structure and stability.Here,we report the influence of molecular crowding environment induced by DMSO on the conformation and stability of G-quadruplex structure.We show that the G-quadruplex-forming sequences such as human telomeric sequence,which may have diverse conformations in different environments,tend to convert their topologies to parallel structures under the molecular crowding stimulated by DMSO.Moreover,DMSO can increase the stability of the parallel and antiparallel topologies,especially the parallel G-quadruplex sequence c-kit,but not the hybrid topologies.Further analysis of c-kit using the CD and NMR technique,combined with the unique structural characteristics of c-kit,reveals that the crowding,dehydration and interaction of DMSO are conductive to the formation and stability of the parallel G-quadruplex.The present study suggests that,DMSO,a common solvent used in DNA experiments,may have a nonnegligible influence on the structure and stability of G-quadruplex.

Priority-based Residential Demand Response for Alleviating Crowding in Distribution Systems

The dynamic pricing environment offers flexibility to the consumers to reschedule their switching appliances.Though the dynamic pricing environment results in several benefits to the utilities and consumers,it also poses some challenges.The crowding among residential customers is one of such challenges.The scheduling of loads at low-cost intervals causes crowding among residential customers,which leads to a fall in voltage of the distribution system below its prescribed limits.In order to prevent crowding phenomena,this paper proposes a priority-based demand response program for local energy communities.In the program,past contributions made by residential houses and demand are considered as essential parameters while calculating the priority factor.The non-linear programming(NLP)model proposed in this study seeks to reschedule loads at low-cost intervals to alleviate crowding phenomena.Since the NLP model does not guarantee global optima due to its non-convex nature,a second-order cone programming model is proposed,which captures power flow characteristics and guarantees global optimum.The proposed formulation is solved using General Algebraic Modeling System(GAMS)software and is tested on a 12.66 kV IEEE 33-bus distribution system,which demonstrates its applicability and efficacy.