Pit Structure Research Articles

Assessment of the sealant/tooth interface using optical coherence tomography

Sealant materials are typically employed in dentistry in order to prevent the development of cavities on the teeth. They prevent bacterial adhesion to enamel, thus arresting the development of demineralization and of caries. In this study, the critical zone of the interface between different sealant materials and the results of the dental work for the teeth processed were investigated ex vivo using swept source (SS) optical coherence tomography (OCT). Optical inspection and X-ray investigation revealed no defects, while SS-OCT proved capable to asses exactly the position, the nature, and the dimensions of each type of these defects. Specifically, different failures were targeted into the structure of pit and fissure sealants, including bubbles, internal cracks, structural defects of sealant material, and structural defects of enamel, with uncovered sealant material and enamel/sealant interface (marginal integrity and marginal adaptation of dental sealant). The investigation of the possible types of defects that may appear into this dental interface was thus accomplished – for the dental practitioner.

Plasmon-enhanced photoluminescence of Si-V centers in diamond from a nanoassembled metal–diamond hybrid structure

Using a facile top-down etching approach, a subwavelength-sized diamond pit structure infilled with semi-ellipsoidal gold nanoparticles was fabricated. The three-dimensional finite-difference time-domain simulations reveal strong localized surface plasmon resonance (LSPR) scattering and enhanced electric field exhibited by this hybrid nanoassembled metal–diamond-pit. Experimentally, with excitation at 633 and 830 nm close to the calculated LSPR wavelength, the photoluminescence (PL) intensities of the peak at 738 nm originating from the single photon source of silicon-vacancy centers in diamond were significantly enhanced by factors of ~100 and ~50, respectively, with respect to that from normal Si-doped diamond without the hybrid structure. By means of time-resolved PL measurements, the decay kinetic mechanisms of the plasmon-related PL enhancement were investigated and are discussed.

Interactive ion-mediated sap flow regulation in olive and laurel stems: physicochemical characteristics of water transport via the pit structure.

Sap water is distributed and utilized through xylem conduits, which are vascular networks of inert pipes important for plant survival. Interestingly, plants can actively regulate water transport using ion-mediated responses and adapt to environmental changes. However, ionic effects on active water transport in vascular plants remain unclear. In this report, the interactive ionic effects on sap transport were systematically investigated for the first time by visualizing the uptake process of ionic solutions of different ion compositions (K+/Ca2+) using synchrotron X-ray and neutron imaging techniques. Ionic solutions with lower K+/Ca2+ ratios induced an increased sap flow rate in stems of Olea europaea L. and Laurus nobilis L. The different ascent rates of ionic solutions depending on K+/Ca2+ ratios at a fixed total concentration increases our understanding of ion-responsiveness in plants from a physicochemical standpoint. Based on these results, effective structural changes in the pit membrane were observed using varying ionic ratios of K+/Ca2+. The formation of electrostatically induced hydrodynamic layers and the ion-responsiveness of hydrogel structures based on Hofmeister series increase our understanding of the mechanism of ion-mediated sap flow control in plants.

Soil Nailing Reliability Optimization Design of Foundation Pit Based on Response Surface Method

Aiming at the randomness and variability of geotechnical parameters, the uniform test and nonparametric regression technique of alternating conditional expectation (ACE) is used to establish the efficiency response surface. On the basis of response surface, the Monte Carlo method was used to research the reliability optimal design and analysis method of soil nailing structure. Considering various failure modes of soil nailing structure, and setting the system failure probability as constraint, and per linear meter length of soil nail as the objective function, than to establish the reliability optimal model of soil nailing structure of foundation pit with the indexes of soil shear strength c, φ and ground overload as random variables. Through an engineering case analysis, the feasibility and effectiveness of this method are verified. Finally, the superiority of the proposed method is proved compared with the deterministic method.

Numerical Simulation on a Deep-Foundation Pit of Shenzhen Holiday Plaza Project

Based on test data of the prestressed anchor cable composite soil nailing wall deformation and internal force of structure of Shenzhen Holiday Plaza foundation pit, the numerical simulation model of foundation pit is established by FLAC3D software. Through the reasonable selection of soil constitutive model and structural unit, the numerical simulation model is consistent with the project practice. The simulation results on horizontal displacement of foundation pit, the internal force of the structure, the surface layer stress and damaged form are reasonable. This does not only provide a strong basis for the optimum design of the foundation pit, but also provide a scientific guidance for engineering application.

Sensilla on the antenna of blow fly, Triceratopyga calliphoroides Rohdendorf (Diptera: Calliphoridae).

Blow fly, Triceratopyga calliphoroides Rohdendorf, is a common and synanthropic species of medical and forensic significance in eastern Asia. Field monitoring studies have indicated that olfaction system plays an important role in guiding the behavior of insect species. To further our understanding of fly olfaction, scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM) are applied to examine the sensillar morphology of adults, with an emphasis on sensory pit and sacculus. Both microtrichiae and several mechanoreceptors are detected on antennal scape and pedicel. Except for these two structures, pedicellar buttons are also found in antennal pedicellar depression after the separation of antennal pedicel and funiculus. Eight types of antennal sensilla are observed on external surface of antennal funiculus (one type of trichoid sensilla, three types of basiconic sensilla, three types of coeloconic sensilla, and one type of clavate-like sensilla), while two types (one type of basiconic sensilla and one type of coeloconic-like sensilla) are detected at the inner surface of sensory pits or sacculus. As the first to investigate cuticular invaginations of blow flies via paraffin section, the internal structure of abundant sensory pits and an excessively complex sacculus on antennal funiculus are revealed. After comparison to other species previously studied, this phenomenon is proved to be the most unique feature of T. calliphoroides, armed with a discussion on its morphology, function, and possible evolutionary implications.

Study of the shape of an optical window in a super-resolution state by electromagnetic-thermal coupled simulation: Effects of melting of an active layer in an optical disc

We performed a multi-physics simulation for the propagation of electromagnetic waves and heat conduction in a super-resolution optical disc that includes an active layer of InSb. Because the change in the optical constant of InSb due to the phase transition is taken into account, the melting of the active layer can be realistically simulated in our calculation. It was found that in the case of an incident light power (P) of 2 mW, a profile of the electric field intensity transmitted through the InSb layer has an asymmetric shape with a narrow peak. This beam-narrowing was suggested to be an essential mechanism of the super-resolution, because a narrower light beam allows the detection of a smaller pit structure than the optical diffraction limit. This beam-narrowing was found to be originating from a small molten region produced in the InSb layer, which works as a mask for light exposure.

Hunter-Gatherer Earth Ovens in the Archaeological Record: Fundamental Concepts

AbstractRemains of earth ovens with rock heating elements of various sizes and configurations are common at hunter-gatherer sites around the world. They span the last 30,000 years in the Old World and some 10,000 years in the New World. Although various foods were baked in these ovens, plants predominate. Earth ovens are ethnographically well documented as family-size and bulk cooking facilities, but related technology and its archaeological signatures remain poorly understood and understudied. These ubiquitous features are often mischaracterized as generic cooking facilities termed hearths. It is proposed that, in fact, most rock “hearths” are heating elements of earth ovens. Reliable identification and interpretation of earth ovens requires documentation of heating elements, pit structure, rock linings, and various remnants thereof. Fundamental technological concepts for investigating their archaeological signatures include thermodynamics, construction designs, and life cycles in systemic context, as informed by ethnographic, archaeological, and experimental data. Earth oven technology explains well the primary purpose of labor-intensive thermal storage for long-term cooking and conserving fuel. Information from the extensive archaeological record of earth ovens on the Edwards Plateau of south-central North America illustrates these points.

Rank-Based Routing Strategy for Named Data Network

NDN (Named Data Networking) is clean-slate architecture for future networking, in which packets carry data names rather than source or destination addresses, being a sharp contrast to today IP architecture. The default routing strategy for NDN is flooding the interest packets to all the possible interfaces which could reach for the data provider or data cache container. Obviously, the default routing strategy is not best way in the actual networking for the heavy load of routing items. This article proposes an interface rank-based routing strategy (RBRS), in which the PIT and FIB structures are detailed and expanded to satisfy the Interest and Data packets transmission, and the interfaces are ranked through a cumulative algorithm for route selection. Through the simulation, RBRS has been proved an adaptive routing mechanism with better performance of network load balance, while reducing the average routing hops and the centric nodes load.

Testing the Roc de Marsal Neandertal “Burial” with Geoarchaeology

The question of intentional Neanderthal interment continues to be debated in paleoanthropology. Among the criteria that can be used to investigate the intentionality of a burial, many of them rely on geoarchaeological data that speak to the context of the human remains. In this paper, we revisit the original attribution of the Roc de Marsal Neandertal infant as an intentional burial by evaluating the sedimentary context, pit structure, and taphonomical aspects of the remains and their integration with data from the most recent excavations at the site. From a geoarchaeological point of view, no clear anthropogenic ritual signature was found. On the contrary, all the available evidence points towards natural formation processes associated with the initial deposition and subsequent burial of the Roc de Marsal Neandertal infant.

Effect of surface microstructure of aluminum coating on corrosion properties of magnetic refrigerant gadolinium

Al coatings with different microstructures were prepared on the surface of Gd using the magnetron sputtering technique to improve its corrosion resistance. The corrosion behaviors for the pure Gd and Gd with Al coating in distilled water were studied using the mass loss and electrochemical performance. As a result, pure Gd without coating shows a certain amount of surface cracks under water flow conditions, whereas the polygonal Al coating decreases the path of the corrosive medium to body due to the existence of eroding pits structure. Compared with the polygonal structure Al coating and pure Gd, the lamellar structure of Al coating exhibits a higher electrochemical protection performance (e.g., a lower corrosion current and higher self-corrosion potential) and no occurrence of pitting corrosion. Due to an effective physical shield, the formation of the lamellar structure protected the inner Gd part from being corroded, and prolonged the duration of cathodic protection.

Hydrolase treatments help unravel the function of intervessel pits in xylem hydraulics

Intervessel pits are structures that play a key role in the efficiency and safety functions of xylem hydraulics. However, little is known about the components of the pit membrane (PM) and their role in hydraulic functions, especially in resistance to cavitation. We tested the effect of commercial chemicals including a cellulase, a hemicellulase, a pectolyase, a proteinase and DTT on xylem hydraulic properties: vulnerability to cavitation (VC) and conductance. The effects were tested on branch segments from Fagus sylvatica (where the effects on pit structure were analyzed using TEM) and Populus tremula. Cellulose hydrolysis resulted in a sharp increase in VC and a significant increase in conductance, related to complete breakdown of the PM. Pectin hydrolysis also induced a sharp increase in VC but with no effect on conductance or pit structure observable by TEM. The other treatments with hemicellulase, proteinase or DTT showed no effect. This study brings evidence that cellulose and pectins are critical components underpinning VC, and that PM components may play distinct roles in the xylem hydraulic safety and efficiency.

Study on Engineering Materials with the Comparison and Discussion of Support Scheme in a Foundation Pit

Taking a deep foundation pit engineering in Taiyuan as research background, this paper used two different supporting structure of foundation pit to make numerical simulation analysis by using Li zheng software. The engineering material had high cost performance. In addition, the paper studied the displacement, bending moment, shear force with the change of the excavation depth, and it came to the conclusion that some outcome can be used for reference in the practical engineering.

Evidence of deep traps in overgrown v-shaped defects in epitaxial GaN layers

The geometric and electronic structure of overgrown v-shaped defects in GaN epitaxial layers are investigated by cross-sectional scanning tunneling microscopy and spectroscopy. The v-defects are found to be hexagonal pit structures delimited by six {112¯2} planes. The electronic properties are inhomogeneous. In some areas the center of the v-defects exhibits a strongly inhibited tunneling current, indicating the presence of deep traps.

Influence of Air Leakage of the Overburden Layer on Pit Temperature from Open Pit to Underground Mining

To mines turning from open pit to underground mining with caving method as transition, air leakage of overburden layer in winter can lead to lower pit temperature, affecting their regular production. The paper is based on the theory of fluid flow in porous media, simulating wind velocity of overburden layer air leakage with FLUENT software and calculating influence of air leakage of the overburden layer on pit temperature under the condition of various porosities and thickness. The conclusion is drawn that overburden layer thickness is above 40m,air leakage influence on pit temperature is relatively little, thus offering scientific basis for rational overburden layer thickness and structure of open pit into underground mining.

A comprehensive stochastic model of phyllosilicate dissolution: Structure and kinematics of etch pits formed on muscovite basal face

Accurate modeling of phyllosilicate dissolution kinetics is a complex problem involving recognition of the influence of structure, chemical composition, lattice defects, and surface topography on local and global dissolution mechanisms. Previous research has provided a wealth of experimental observations that illustrate the dominant role of etch pits in formation of the steps on the basal face of mica during the dissolution reaction. The shape of the etch pits bears important information on surface reactivity and dissolution rate anisotropy at given environmental conditions. In order to understand the influence of various kinetic factors on etch pit and step morphology, as well as the overall dissolution mechanisms, we have developed a new Kinetic Monte Carlo model simulating dissolution of these minerals. The model considers the effects of chemical composition, structural position, the number of first and second-order nearest neighbors and the steric hindrance of surface atoms on the etch pit morphology and step reactivity. We describe several complexity levels of the model which are characterized by the different ranges of the effects considered. These levels were developed in order to find the most optimal model capable of predicting experimentally observed etch pit morphologies. Our simulation results show that the models based on the sole consideration of the first coordination sphere in general can predict etch pit shape and orientation, while recognition of the site reactivity difference imposed by the steric factors helps us to explain the geometry of monolayer pit superposition. However, the distinction of the ledge and kink sites at all the experimentally observed surface steps is possible only with the use of the second-order neighbors. Based on these findings, we propose a mechanistic scheme explaining the role of the first and second-order coordination numbers in step stabilization and correct prediction of the etch pit structure.

EXAMINING ORTHODOXY IN THE UPPER SAN JUAN REGION OF THE NORTHERN SOUTHWEST

Conventional interpretations of architecture and artifacts have concluded that the Ancestral Puebloans of the Upper San Juan (or uplands of the Eastern Mesa Verde) region were slow to respond to cultural changes that were occurring in the Central Mesa Verde region to the west and Chaco/Cibola region to the South. Rather than being a “cultural backwater,” this paper examines the idea that these groups practiced an orthodox form of the Puebloan lifeway, rejecting the changes that were occurring elsewhere in the northern Southwest. During the Pueblo II period (A.D. 900–1150), this orthodoxy is evident in the retention of material culture and architecture that is reminiscent of earlier time periods, such as plain gray ceramics and pit structures. The rejection of change in the Upper San Juan region is significant because it argues for a socially diverse landscape inhabited by both progressive groups accepting of change and groups that had a more conservative attitude toward change over time.

Arabidopsis thaliana as a model species for xylem hydraulics: does size matter?

While Arabidopsis thaliana has been proposed as a model species for wood development, the potential of this tiny herb for studying xylem hydraulics remains unexplored and anticipated by scepticism. Inflorescence stems of A. thaliana were used to measure hydraulic conductivity and cavitation resistance, whereas light and electron microscopy allowed observations of vessels. In wild-type plants, measured and theoretical conductivity showed a significant correlation (R 2 = 0.80, P < 0.01). Moreover, scaling of vessel dimensions and intervessel pit structure of A. thaliana were consistent with structure–function relationships of woody plants. The reliability and resolution of the hydraulic methods applied to measure vulnerability to cavitation were addressed by comparing plants grown under different photoperiods or different mutant lines. Sigmoid vulnerability curves of A. thaliana indicated a pressure corresponding to 50% loss of hydraulic conductance (P 50) between –3 and –2.5MPa for short-day and long-day plants, respectively. Polygalacturonase mutants showed a higher P 50 value (–2.25MPa), suggesting a role for pectins in vulnerability to cavitation. The application of A. thaliana as a model species for xylem hydraulics provides exciting possibilities for (1) exploring the molecular basis of xylem anatomical features and (2) understanding genetic mechanisms behind xylem functional traits such as cavitation resistance. Compared to perennial woody species, however, the lesser amount of xylem in A. thaliana has its limitations.

Structure and Clinical Significance of Central Optic Disc Pits

To assess the structure of central optic disc pits (ODPs) using enhanced-depth imaging optical coherence tomography (EDI OCT) and to ascertain their clinical significance. Prospective, cross-sectional study. Patients with an ophthalmoscopically visible central ODP in either eye, irrespective of accompanying ocular disease, were enrolled from the neuro-ophthalmology and glaucoma referral practices. Each subject with a central ODP was matched with 2 healthy subjects with normal-appearing optic disc within 5 years of age. Each participant received a complete ophthalmologic examination including standard automated perimetry, retinal nerve fiber layer (RNFL) thickness measurement by OCT, and serial horizontal and vertical cross-sectional EDI OCT of the optic nerve head. Structure of the lamina cribrosa (LC) in relation to the central ODP in EDI OCT images. Eighteen eyes (13 subjects) with a central ODP and 52 healthy eyes (26 controls) were included. Four eyes (2 subjects) with a central ODP were otherwise normal with intact macula, neuroretinal rim, RNFL, and visual field. Fourteen eyes (11 subjects) with a central ODP had glaucoma with glaucomatous neuroretinal rim thinning, RNFL loss, and corresponding visual field defect. No eye had associated maculopathy. On EDI OCT, the central ODP corresponded with a full-thickness defect in the LC center with no serous retinal detachment or herniation of neural tissue through the LC defect. Central ODPs were separated from (type 1) or merged with (type 2) the LC opening for the central retinal vascular trunk. In control eyes, no LC defect was detected. Central ODPs are full-thickness LC defects unassociated with maculopathy and different from glaucomatous acquired pits of the optic nerve, which represent focal laminar defect adjacent to the disc edge.

Probe-based confocal laser endomicroscopy: A new method for quantitative analysis of pit structure in healthy and Crohn's disease patients

Probe-based confocal laser endomicroscopy enables microscopic examination of the digestive mucosa. (1) To identify and validate quantitative endomicroscopic criteria for evaluation of the colonic mucosa and (2) to compare these criteria between healthy and Crohn's disease patients in clinical remission. Six healthy controls and ten Crohn's disease patients in clinical remission were included in this prospective study. Methylene blue-stained biopsies of the right colon and corresponding endomicroscopic images were analyzed. Major axis, minor axis, and major axis/minor axis ratio of crypt lumens were quantified. Quantitative assessment was performed on 21 ± 4 crypt lumens per patient. Major axis/minor axis ratio values measured with endomicroscopy or methylene blue-stained biopsies were linearly correlated (r=0.63, p=0.01). All macroscopically inflamed mucosa had values of major axis/minor axis ratio higher than the median of controls. Interestingly, 50% (3/6) of Crohn's disease patients with macroscopically normal mucosa had also a higher ratio than pooled controls. Histological analysis showed that 6/7 patients with major axis/minor axis ratio superior to 1.7 had microscopic inflammation. Probe-based confocal laser endomicroscopy allows quantitative analysis of colonic pit structure. Endomicroscopic analysis of major axis/minor axis ratio allows the detection of microscopic residual inflammation with greater accuracy than standard endoscopy in Crohn's disease patients in clinical remission.