Structure Of Site Research Articles

Integrated approach for seismic wave prediction and structural evaluation of Oya tuff quarry underground spaces: Field observations and numerical modeling

This study evaluates the structural stability of large underground spaces in seismic conditions, represented by the Oya underground stone mining plant. By directly monitoring the seismic response of the underground mining site, significant earthquake activities at the plate boundaries of the Tokyo region and Ibaraki Prefecture offshore area were observed. Additionally, through an in-depth analysis of seismic records from different locations within the underground structure, the dynamic characteristics and motion patterns of the Oya underground stone mining plant were revealed, revealing its movement trajectory during earthquakes. Additionally, this study innovatively applied seismic waves measured at the original site as input parameters and artificially generated seismic waves based on their response spectra. A numerical analysis was performed after ensuring the model's high correlation with the original site was met. The findings demonstrate that the results of both parameter input methods are confirmable and valuable. Under severe seismic conditions, instability was observed in some regions of the underground mining site. The study also discusses the location and damage mechanisms of the mining site's structure under seismic effects, providing valuable insights for the safety assessment of similar large underground spaces and proposing new approaches for selecting input parameters in seismic analysis.

Synthesis of Metal-Nitrogen-Carbon Electrocatalysts with Atomically Regulated Nitrogen-Doped Polycyclic Aromatic Hydrocarbons.

Tuning the active site structure of metal-nitrogen-carbon electrocatalysts has recently attracted increasing interest. Herein, we report a bottom-up synthesis strategy in which atomically regulated N-doped polycyclic aromatic hydrocarbons (N-PAHs) of NxC42-x (x = 1, 2, 3, 4) were used as ligands to allow tuning of the active site's structures of M-Nx and establish correlations between the structures and electrocatalytic properties. Based on the synthesis process, detailed characterization, and DFT calculation results, active structures of Nx-Fe1-Nx in Fe1-Nx/RGO catalysts were constructed. The results demonstrated that the extra uncoordinated N atoms around the Fe1-N4 moieties disrupted the π-conjugated NxC42-x ligands, which led to more localized electronic state in the Fe1-N4 moieties and superior catalytic performance. Especially, the Fe1-N4/RGO exhibited optimized performance for ORR with E1/2 increasing by 80 mV and Jk at 0.85 V improved 18 times (compared with Fe1-N1/RGO). This synthesis strategy utilizing N-PAHs holds significant promise for enhancing the controllability of metal-nitrogen-carbon electrocatalyst preparation.

Effect of Phosphorus Modulation in Iron Single-Atom Catalysts for Peroxidase Mimicking.

Fe-N-C single-atom catalysts (SACs) exhibit excellent peroxidase (POD)-like catalytic activity, owing to their well-defined isolated iron active sites on the carbon substrate, which effectively mimic the structure of natural peroxidase's active center. To further meet the requirements of diverse biosensing applications, SAC POD-like activity still needs to be continuously enhanced. Herein, a phosphorus (P) heteroatom is introduced to boost the POD-like activity of Fe-N-C SACs. A 1Dcarbon nanowire (FeNCP/NW) catalyst with enriched Fe-N4 active sites is designed and synthesized, and P atoms are doped in the carbon matrix to affect the Fe center through long-range interaction. The experimental results show that the P-doping process can boost the POD-like activity more than the non-P-doped one, with excellent selectivity and stability. The mechanism analysis results show that the introduction of P into SAC can greatly enhance POD-like activity initially, but its effect becomes insignificant with increasing amount of P. As a proof of concept, FeNCP/NW is employed in an enzyme cascade platform for highly sensitive colorimetric detection of the neurotransmitter acetylcholine.

Revisitando os Chões de Alpompé com técnicas de deteção remota: novas evidências sobre os sistemas defensivos Romano-Republicanos

O planalto dos Chões de Alpompé, em Santarém, foi, pelo menos desde os anos 50 do século XX, alvo de numerosos trabalhos de prospeção e até de campanhas de escavação e acompanhamento de obras agrícolas. Tais trabalhos proporcionaram a recolha de inúmeros materiais arqueológicos, muitos dos quais já publicados, que deixam antever uma relevante ocupação humana durante a Idade do Ferro e época Romano-Republicana. Todavia, a definição dos seus sistemas defensivos foi sempre difícil, situação que resulta em grande parte da densa cobertura florestal que o cobre. A recente disponibilidade, para esta zona do baixo Vale do Tejo, de dados de laser aéreo, bem como a sua combinação com fotografia aérea histórica, permitiu identificar e mapear novas estruturas arqueológicas que autorizam uma visão renovada sobre as estruturas do sítio. Esta leitura tem também em consideração os recentes dados obtidos nas intervenções arqueológicas de escavação e acompanhamento decorridas entre 2015 e 2018, que permitiram esclarecer algumas questões relevantes sobre estes sistemas defensivos.

Reversing allosteric communication: From detecting allosteric sites to inducing and tuning targeted allosteric response.

The omnipresence of allosteric regulation together with the fundamental role of structural dynamics in this phenomenon have initiated a great interest to the detection of regulatory exosites and design of corresponding effectors. However, despite a general consensus on the key role of dynamics most of the earlier efforts on the prediction of allosteric sites are heavily crippled by the static nature of the underlying methods, which are either structure-based approaches seeking for deep surface pockets typical for “traditional” orthosteric drugs or sequence-based techniques exploiting the conservation of protein sequences. Because of the critical role of global protein dynamics in allosteric signaling, we investigate the hypothesis of reversibility in allosteric communication, according to which allosteric sites can be detected via the perturbation of the functional sites. The reversibility is tested here using our structure-based perturbation model of allostery, which allows one to analyze the causality and energetics of allosteric communication. We validate the “reverse perturbation” hypothesis and its predictive power on a set of classical allosteric proteins, then, on the independent extended benchmark set. We also show that, in addition to known allosteric sites, the perturbation of the functional sites unravels rather extended protein regions, which can host latent regulatory exosites. These protein parts that are dynamically coupled with functional sites can also be used for inducing and tuning allosteric communication, and an exhaustive exploration of the per-residue contributions to allosteric effects can eventually lead to the optimal modulation of protein activity. The site-effector interactions necessary for a specific mode and level of allosteric communication can be fine-tuned by adjusting the site’s structure to an available effector molecule and by the design or selection of an appropriate ligand.

Automating the Extraction of Static Content and Dynamic Behaviour from e-Commerce Websites

Abstract: E-commerce website owners rely heavily on analysing and summarising the behaviour of costumers, making efforts to influence user actions and optimize success metrics. Machine learning and data mining techniques have been applied in this field, greatly influencing the Internet marketing activities. When faced with a new e-commerce website, the data scientist starts a process of collecting real-time and historical data about it, analysing and transforming this data in order to get a grasp into the website and its users. Data scientists commonly resort to tracking domain-specific events, requiring code modification of the web pages. This paper proposes an alternative approach to retrieve information from a given e-commerce website, collecting data from the site's structure, retrieving semantic information in predefined locations and analysing user's access logs, thus enabling the development of accurate models for predicting users’ future behaviour. This is accomplished by the application of a web mining process, comprehending the site's structure, content and usage in a pipeline, resulting in a web graph of the website, complemented with a categorization of each page and the website's archetypical user profiles.

Building a Culturally-Competent Web Site

The internationalization of Web sites requires Web designers to provide effective navigation experience for users from diverse cultural backgrounds. This research investigates the effect of cultural cognitive style on user perception of Web site structure characteristics and performance on the Web site, and the subsequent user satisfaction towards the Web site. More specifically, the authors focus on the breadth versus depth of a Web site's structure. A laboratory experiment involving participants from China and the United States was conducted to test the hypotheses. The results showed that cultural cognitive style and Web site structure indeed interact to affect user perception and performance. People with holistic and analytic cultural cognitive styles displayed different perceived navigability and user performance on “broad” and “deep” Web sites. This study adds a cultural dimension to our knowledge on how Web site structure can affect users' experience. It also suggests pragmatic strategies for Web site design practitioners to improve website design in order to produce compelling navigation experience for users from diverse cultures.

A GIS-Interface Web Site: Exploratory Learning for Geography Curriculum

Although Web-based instruction provides learners with sufficient resources for self-paced learning, previous studies have confirmed that browsing navigation-oriented Web sites possibly hampers users’ comprehension of information. Web sites designed as “categories of materials” for navigation demand more cognitive effort from users to orient their navigation behavior according to the Web site's structure. This study designs a GIS-interface Web site for students to experiment with exploratory learning. Learners interact with maps to retrieve related information and actively organize what they read to develop their own cognitive models. This research uses an exploratory learning Web site and a structured learning Web site to compare learners’ comprehension of the content and behavior when browsing the Web site in an experimental design. The results show that learners using the exploratory learning Web site performed better in content interpretation than learners exposed to the structured Web site when employing diverse strategies.

Multi-image stitching and scene reconstruction for evaluating defect evolution in structures

It is well-recognized that civil infrastructure monitoring approaches that rely on visual approaches will continue to be an important methodology for condition assessment of such systems. Current inspection standards for structures such as bridges require an inspector to travel to a target structure site and visually assess the structure's condition. A less time-consuming and inexpensive alternative to current visual monitoring methods is to use a system that could inspect structures remotely and also more frequently. This article presents and evaluates the underlying technical elements for the development of an integrated inspection software tool that is based on the use of inexpensive digital cameras. For this purpose, digital cameras are appropriately mounted on a structure (e.g., a bridge) and can zoom or rotate in three directions (similar to traffic cameras). They are remotely controlled by an inspector, which allows the visual assessment of the structure's condition by looking at images captured by the cameras. By not having to travel to the structure's site, other issues related to safety considerations and traffic detouring are consequently bypassed. The proposed system gives an inspector the ability to compare the current (visual) situation of a structure with its former condition. If an inspector notices a defect in the current view, he/she can request a reconstruction of the same view using images that were previously captured and automatically stored in a database. Furthermore, by generating databases that consist of periodically captured images of a structure, the proposed system allows an inspector to evaluate the evolution of changes by simultaneously comparing the structure's condition at different time periods. The essential components of the proposed virtual image reconstruction system are: keypoint detection, keypoint matching, image selection, outlier exclusion, bundle adjustment, composition, and cropping. Several illustrative examples are presented in this article to demonstrate the capabilities, as well as the limitations, of the proposed vision-based inspection procedure.

Do synthetic Fe-zeolites mimic biological Fe-porphyrins in reactions with nitric oxide?

Iron containing ZSM-5 zeolites is extremely active in nitrous oxide decomposition. This reaction involves atomic oxygen species known as “alpha oxygen” on iron sites. Despite the multiple techniques devoted to its characterization, the active sites’ structure remains nevertheless unknown. Herein, these centers are quantified via surface titration by nitrous oxide followed by temperature programmed desorption and characterized via nitric oxide probe molecule followed by infrared spectroscopy. In this latter case, two mono-nitrosyl species differing in the bonds’ geometry are observed on the iron centers. Moreover, upon NO evacuation, the two corresponding IR bands suddenly transit to lower wavenumbers. A mirror trend is also reported in biology when NO interacts with iron porphyrins and explained in terms of linear to bent Fe–N–O modification. This structural change is reversible upon addition/evacuation of NO. In the present report, the same reversible nitrosyl transition is observed for Fe–ZSM-5. Based on the close analogies found, the active site's structure in Fe–ZSM-5 is built-up from the porphyrinatoiron(II) model.

Toward understanding the inactivation mechanism of monooxygenase P450 BM‐3 by organic cosolvents: A molecular dynamics simulation study

Cytochrome P450 BM-3 from Bacillus megaterium is an extensively studied enzyme for industrial applications. A major focus of current protein engineering research is directed to improving the catalytic performance of P450 BM-3 toward nonnatural substrates of industrial importance in the presence of organic solvents or cosolvents. For the latter reason, it is important to study the effect of organic cosolvent molecules on the structure and dynamics of the enzyme, in particular, the effect of cosolvent molecules on the active site's structure and dynamics. In this paper, we have studied, using molecular dynamics (MD) simulations, the F87A mutant of P450 BM-3 in the presence of DMSO as cosolvent, to understand the role of the F87A substitution for its catalytic activity. This mutant exhibits an altered regioselectivity and substrate specificity compared with wild-type; however, it has lower tolerance toward DMSO. The simulation results offer an explanation for the DMSO sensitivity of the F87A mutant. Our simulation results show that the F87 side chain prevents the disturbance of the water molecule bound to the heme iron by DMSO molecules. The absence of the phenyl ring in F87A mutant promotes interactions of the DMSO molecule with the heme iron resulting in water displacement by DMSO at the catalytic heme center.

Influence of spatial ability in navigation: using look-ahead breadcrumbs on The Web

Breadcrumbs are a type of navigational aid intended to help users of large well-structured websites by providing information about the location of the current webpage within the site's structure. The phenomenon of user disorientation (feeling lost) when using hypertext in abstract information-rich environments such as WWW-based directories is well known. Earlier experiments have been unable to explain why visual mediators that improve navigation for people with lower Spatial Ability (SA) seems to have the opposite effect for other people. Results from our experiment indicate that spatial ability influenced navigation efficiency in navigating a vast hierarchical website. Users in the higher SA group were more efficient and had a different (marginally significant) preference for website's breadcrumbs over the browser's Back button. There was no significant difference for time or accuracy between the two groups. Those results suggest that users with lower SA use different approaches to navigating websites than others.

?Work it out with your wife?: Gendered Expectations and Parenting Rhetoric Online

Parents are increasingly seeking information about parenting online. However, like traditional sources of parenting instruction-family, friends, and advice books-online parenting resources communicate not only suggestions about childrearing, but also gendered expectations about parental roles. While the Internet provides space for a wide range of attitudes about parenting, from individual websites to online magazines to large commercial sites, many parents make use of the latter. One such representative site, BabyCenter, initially appears progressive in its attitude about equal division of labor between mothers and fathers, but a close rhetorical analysis of the site's structure and language reveals very traditional expectations in which the mother is primarily responsible for child care. These attitudes influence visitors to the site as they participate in community spaces, engaging in dialogue with other parents. This article analyzes how these attitudes are presented, howparents choose online parenting sites, and how they respond to and resist the expectations they find there.

Adaptive neural network clustering of Web users

The degree of personalization that a Web site offers in presenting its services to users is an important attribute contributing to the site's popularity. Web server access logs contain substantial data about user access patterns. One way to solve this problem is to group users on the basis of their Web interests and then organize the site's structure according to the needs of different groups. Two main difficulties inhibit this approach: the essentially infinite diversity of user interests and the change in these interests with time. We have developed a clustering algorithm that groups users according to their Web access patterns. The algorithm is based on the ART1 version of adaptive resonance theory. In our ART1-based algorithm, a prototype vector represents each user cluster by generalizing the URLs most frequently accessed by all cluster members. We have compared our algorithm's performance with the traditional k-means clustering algorithm. Results showed that the ART1-based technique performed better in terms of intracluster distances. We also applied the technique in a prefetching scheme that predicts future user requests.

A Framework for the Evaluation of Session Reconstruction Heuristics in Web-Usage Analysis

Web-usage mining has become the subject of intensive research, as its potential for personalized services, adaptive Web sites and customer profiling is recognized. However, the reliability of Web-usage mining results depends heavily on the proper preparation of the input datasets. In particular, errors in the reconstruction of sessions and incomplete tracing of users’ activities in a site can easily result in invalid patterns and wrong conclusions. In this study, we evaluate the performance of heuristics employed to reconstruct sessions from the server log data. Such heuristics are called to partition activities first by user and then by visit of the user in the site, where user identification mechanisms, such as cookies, may or may not be available. We propose a set of performance measures that are sensitive to two types of reconstruction errors and appropriate for different applications in knowledge discovery (KDD) applications. We have tested our framework on the Web server data of a frame-based Web site. The first experiment concerned a specific KDD application and has shown the sensitivity of the heuristics to particularities of the site's structure and traffic. The second experiment is not bound to a specific application but rather compares the performance of the heuristics for different measures and thus for different application types. Our results show that there is no single best heuristic, but our measures help the analyst in the selection of the heuristic best suited for the application at hand.

Structure of the Active Sites on H3PO4/ZrO2 Catalysts for Dimethyl Carbonate Synthesis from Methanol and Carbon Dioxide

The catalytic properties of H3PO4/ZrO2 catalysts for dimethyl carbonate (DMC) synthesis from CH3OH and CO2 were investigated. The modification of ZrO2 with H3PO4 promoted the activity for selective DMC formation. The characterization of H3PO4/ZrO2 catalysts was performed by means of BET, XRD, 31P MAS NMR, LRS, DRIFT, and NH3-TPD. From the characterization results, it was determined that ZrO2 had Lewis acid sites and did not have Bronsted acid sites. The presence of Bronsted acid sites as well as Lewis acid sites was observed on H3PO4/ZrO2 (P/Zr = 0.05). The acidity of the Bronsted sites is weak, and the site's structure is a bridged OH. Furthermore, this Bronsted site is formed by the interaction between tetragonal Zr and P. In the reaction scheme of DMC formation, the Bronsted acid site can contribute to CH3OH activation and to the enhancement of the catalytic activity.

Catching the boat with Strudel

The Strudel system applies concepts from database management systems to the process of building Web sites. Strudel's key idea is separating the management of the site's data, the creation and management of the site's structure, and the visual presentation of the site's pages. First, the site builder creates a uniform model of all data available at the site. Second, the builder uses this model to declaratively define the Web site's structure by applying a “site-definition query” to the underlying data. The result of evaluating this query is a “site graph”, which represents both the site's content and structure. Third, the builder specifies the visual presentation of pages in Strudel's HTML-template language. The data model underlying Strudel is a semi-structured model of labeled directed graphs. We describe Strudel's key characteristics, report on our experiences using Strudel, and present the technical problems that arose from our experience. We describe our experience constructing several Web sites with Strudel and discuss the impact of potential users' requirements on Strudel's design. We address two main questions: (1) when does a declarative specification of site structure provide significant benefits, and (2) what are the main advantages provided by the semi-structured data model.

Trapping of Guests in Rare Gas Matrices: Simulation and Experiment

AbstractMolecular dynamics simulations of the trapping of molecules in a rare gas matrix are presented. In distinction with most previous simulations, a site's structure is not obtained by a guess and optimize method, but is found by allowing the lattice to grow by adding atoms from the vapor onto a “seed” crystal. Simple pairwise potentials are used to simulate the growth of rare gas matrices containing some small guests, including diatomic and triatomic molecules. Changes in the structure and energy of the solid are calculated, as well as the vibrational frequencies of the trapped molecules, providing an estimate for the matrix shift. The method also allows the estimate of small changes in the interatomic distances in the trapped molecules, as compared to the gas phase values. Novel site geometries, in which the host lattice atoms are displaced from their equilibrium crystal positions, are observed for guest molecules that can strongly distort the lattice because of asymmetry or size mismatches.

Molecular dynamics simulations of rare gas matrix deposition

Molecular dynamics simulations of the trapping of molecules in a rare gas matrix based on a fcc lattice is presented. In distinction with most previous simulations, a site's structure is not obtained by a guess and optimize method, but is found by allowing the lattice to grow by adding atoms from the vapor onto the potential field of a “seed” crystal. Simple pairwise potentials are used to simulate the growth of rare gas matrices containing some small guests, including the diatomic molecules N2, NBr and Br2. Changes in the structure and energy of the solid are calculated, as well as the vibrational frequencies of the trapped molecules, yielding the matrix shift. Novel site geometries, in which the host lattice atoms are displaced from their equilibrium crystal positions, are observed for guest molecules that can strongly distort the lattice because of asymmetry or size mismatches. In these cases, rapid cooling of the incoming atom is essential to the formation of several distinct trapping sites.

23] Bioluminescence test for genotoxic agents

The bioluminescence test (BLT) for genotoxic agents uses dark mutants of luminous bacteria, and determines the ability of the tested agent to restore the luminescent state. Three groups of genotoxic agents have been shown to be active in the BLT: (1) direct mutagens being base substitution or frame-shift agents, (2) DNA-damaging agents and DNA synthesis inhibitors, and (3) DNA-intercalating agents. The primary lesion of the dark mutant is still unknown; however, accumulating evidence suggests that the transduction of the luminescence operon is under continuous repression probably by an intercistronic repressor. Restoring the luminescence of the repressed dark mutant can theoretically be achieved by three independent events: (1) blocking the formation of the repressor; altering its or the operator site's structure, (2) inactivating the repressor of the luminescence system, and (3) changing the physical configuration of the DNA, thus allowing unrepressed transcription of the luciferase operon. Blocking the formation of the repressor or altering its ability to bind to the operon site is expected from direct mutagens. Technically the BLT is very simple; sterility of the assay mixture is not essential, volatile agents could be tested, and the toxicity of the tested chemical is determined concomitant with its genotoxicity. The BLT can be run automatically and up to 50 chemicals can be tested in a day.