Structure-related Parameters Research Articles

Long-term effects of Zoledronic acid on alveolar bone remodeling and quality in the jaw of an oncological rat model

Despite great interest in bisphosphonate-induced osteonecrosis of the jaw (ONJ), the underlying pathology remains a matter of debate. In most reports, the etiology of ONJ seems to be ascribed to bisphosphonate-related over suppression of bone remodeling. While suppression of bone remodeling is indeed the prime action mechanism of bisphosphonates, the destructive ONJ effects at the level of the jaw bone are ignored or minimalized when prescribing these drugs. The present study therefore investigated the long-term effects of oncological Zoledronic Acid (ZA) doses on the three factors which may comprise jaw bone:(1) bone quantity, (2) bone structure and (3) bone mineral density (BMD). Twentyfour, healthy, Wistar rats were randomly divided in an experimental group (n = 12) receiving 0.6 mg/kg body weight/month ZA and a control group (n = 12) receiving an equal volume of saline for 5 consecutive months. The ZA doses were equivalent to the doses given to oncologic patients. After animal sacrifice, their mandibles were ex vivo scanned using 1174 micro-CT (Bruker) and the obtained scans were spatially aligned. One mean volume of interest containing only trabecular bone below the apex of the molars was selected, in which 3D quantitative morphometry and BMD were calculated using CT-Analyser (Bruker). Structural-related parameters showed significantly (P < 0.001) increased osteoslerotic characteristics of the alveolar bone (↑ Tb.Pf; ↓ Tb.Sp; ↓Tb.N; ↓ SMI; ↓ Conn.Dn) in ZA-treated rats as compared to the controls. These findings were confirmed by a significantly (P < 0.001) increased bone quantity (↑ BV/TV; ↑ Tb.Th; ↓ BS/TV; ↓ Po[tot]). Finally, the alveolar bone displayed a significantly (P < 0.001) higher BMD after prolonged ZA therapy. These results are strongly supportive for bisphosphonateinduced oversuppression of alveolar bone remodeling. The bone becomes more sclerotic leading to less vascularization and an ONJ prone jaw

Enhanced dual-band absorption of molybdenum disulfide using a plasmonic perfect absorber.

In order to remarkably enhance its absorption capability, a tunable dual-band MoS2-based perfect absorber inspired by metal-insulator-metal (MIM) metamaterial is proposed. By using the finite-difference time-domain (FDTD) simulations, dual-band perfect absorption peaks are realized in the visible light regime, and the absorptions of monolayer MoS2 are enhanced up to 57% and 80.5% at the peak wavelengths. By manipulating related structural parameters, the peak wavelengths of MoS2 absorption can be separately tuned in a wide wavelength range. Furthermore, the proposed absorber can tolerate a relatively wide range of incident angles and demonstrate polarization-dependence.

A comparison of the structures of >300 °C fractions in six Chinese shale oils obtained from different locations using 1H NMR, 13C NMR and FT-IR analyses

Structural features of >300°C fractions of six Chinese shale oils, namely the Huadian, Wangqing, Fushun, Longkou, Maoming and Yaojie oil, have been characterized using 1H nuclear magnetic resonance, 13C nuclear magnetic resonance and Fourier transform infrared techniques. Based upon the results obtained from 1H nuclear magnetic resonance and 13C nuclear magnetic resonance, the distribution of various types of hydrogen and carbon atoms, and related structural parameters in >300°C fractions were determined. Different types of functional groups were studied based on the curve-fitting analysis of Fourier transform infrared spectra with Gaussian function. The results showed that the >300°C fraction of Huadian shale oil had the highest ratio of aliphatic carbon among the six samples. Meanwhile, the average carbon number of substituents in Huadian oil’s >300°C fraction was the highest, and had the value of 8.98. Moreover, the Huadian sample owned the lowest degree of branching of aliphatic chain, whereas it had the highest ratios of CH2 and CH3. These results indicated that, in Huadian oil’s >300°C fraction, the alkyl carbon chains were longer, whereas the branched chains were less (in number) compared to other samples. Furthermore, the curve-fitting analysis indicated that 2 and 3 adjacent H deformations were dominant in aromatic structures. The oxygen-containing groups in >300°C fraction of Chinese shale oil were mainly the CO groups, followed by the COH groups, OCO groups and conjugated CO groups. In summary, >300°C fractions of Chinese shale oils showed similar differences with regards to the elemental compositions and functional groups.

A novel 4H-SiC MESFET with multi-recessed p-buffer layer for high energy-efficiency applications

In this paper, a novel structure named 4H-SiC metal semiconductor field effect transistor with multi-recessed p-buffer layer named MRB MESFET is proposed and simulated. The design of the new structure takes the power added efficiency into account to reduce energy consumption. The channel is assisted to deplete further and the electric field in the drift region for the new structure is modulated by utilizing a multi-recessed p-buffer layer. Thus, the superior gate-source capacitance is obtained and the larger saturation drain current and breakdown voltage are achieved compared with the double-recessed p-buffer layer structure named DRB MESFET. The simulated results demonstrate that the breakdown voltage and the saturation drain current of the MRB MESFET are about 57.89% and 5.63% greater than that of the DRB MESFET. There is an improvement of 86.5% in the maximum output power density for the proposed structure compared with that of the DRB MESFET when the both RF characteristics are similar to. The related structure parameters m = 0.10 μm, n = 0.20 μm are optimized at the beneficial maximum output power density (Pmax), cut-off frequency (fT) and power added efficiency (PAE). All the results show that the advantages and the potential capacities of the MRB MESFET are greater than the DRB MESFET.

Conformational Entropy from Slowly Relaxing Local Structure Analysis of 15N-H Relaxation in Proteins: Application to Pheromone Binding to MUP-I in the 283-308 K Temperature Range.

The slowly relaxing local structure (SRLS) approach is applied to 15N-H relaxation from the major urinary protein I (MUP-I), and its complex with pheromone 2-sec-butyl-4,5-dihydrothiazol. The objective is to elucidate dynamics, and binding-induced changes in conformational entropy. Experimental data acquired previously in the 283-308 K temperature range are used. The N-H bond is found to reorient globally with correlation time, τ1,0, and locally with correlation time, τ2,0, where τ1,0 ≫ τ2,0. The local motion is restricted by the potential u = -c02D002, where D002 is the Wigner rotation matrix element for L = 2, K = 0, and c02 evaluates the strength of the potential. u yields straightforwardly the order parameter, ⟨D002⟩, and the conformational entropy, Sk, both given by Peq = exp(-u). The deviation of the local ordering/local diffusion axis from the N-H bond, given by the angle β, is also determined. We find that c02 ≅ 18 ± 4 and τ2,0 = 0-170 ps for ligand-free MUP-I, whereas c02 ≅ 15 ± 4 and τ2,0 = 20-270 ps for ligand-bound MUP-I. β is in the 0-10° range. c02 and τ2,0 decrease, whereas β increases, when the temperature is increased from 283 to 308 K. Thus, SRLS provides physically well-defined structure-related (c02 and ⟨D002⟩), motion-related (τ2,0), geometry-related (β), and binding-related (Sk) local parameters, and their temperature-dependences. Intriguingly, upon pheromone binding the conformational entropy of MUP-I decreases at high temperature and increases at low temperature. The very same experimental data were analyzed previously with the model-free (MF) method which yielded "global" (in this context, "relating to the entire 283-308 K range") amplitude (S2) and rate (τe) of the local motion, and a phenomenological exchange term (Rex). S2 is found to decrease (implying implicitly "global" increase in Sk) upon pheromone binding.

Supramolecular microporous structures based on carbon nanotubes and coordinating cumene (C9H12) molecules

A method has been proposed for the formation of self-organized ensembles of carbon nanotubes with the use of coordinating cumene molecules and the development of secondary porosity in the obtained structures. It has been shown that the fraction of nanotubes coordinated into an array grows with increasing molar ratio between cumene molecules and carbon nanotubes upon the synthesis of the supramolecular structures. The secondary porosity develops due to partial desorption of the coordinating molecules from the obtained structure. A supramolecular structure with a residual cumene content of 50 wt % possesses the best adsorption characteristics for the described system. Specific adsorption of nitrogen on the “carbon nanotubes–cumene (50 wt %)” supramolecular structure at 293 K is more than an order of magnitude higher than that on the initial nanotubes. The structure-related energy parameters of the experimentally obtained supramolecular systems have been determined by molecular dynamics methods. The calculation in terms of the theory of volume filling of micropores has shown that the secondary pores of the obtained structures can accumulate methane and hydrogen in amounts as large as 213 nm3/m3 and 4 wt %, respectively.

Effect of relative stiffness on moment redistribution in reinforced high-strength concrete beams

Moment redistribution in continuous concrete beams is primarily a structural aspect of behaviour, since it is a consequence of structural redundancy. However, the current design codes do not take this structural characteristic into consideration and therefore may not be reasonable when predicting the permissible moment redistribution. In this paper, moment redistribution in reinforced high-strength concrete (HSC) beams is analysed, focusing on the effect of relative stiffness represented by the structure-related parameter ρs2/ρs1 (where ρs1 and ρs2 are the tensile steel ratios over positive and negative moment regions, respectively). A numerical evaluation was conducted on two-span continuous beams made of HSC having a cylinder compressive strength of 90 MPa. A wide range of ρs2/ρs1 was produced by varying either ρs1 or ρs2 from 0·81% to 6·06%. The results show that the ρs2/ρs1 ratio is a critical parameter influencing the global moment redistribution behaviour. Modifications to the Canadian Standards Association and American Concrete Institute equations are proposed for calculating the moment redistribution at the ultimate state. By introducing the parameter ρs2/ρs1, the proposed modified equations are shown to have an excellent fit to the actual redistribution values.

Efficient estimation of acid gases (CO2 and H2S) absorption in ionic liquids

This work presents the application of computer based models including radial basis function neural network optimized by particle swarm optimization method (PSO-RBF), multilayer perceptron neural network (MLP-NN), least square support vector machine optimized by coupled simulated annealing (CSA-LSSVM) and adaptive neuro-fuzzy inference system trained by hybrid method (Hybrid-ANFIS) for prediction of solubility of CO2 and H2S in ionic liquids (ILs). A high-valued data base including 2930 data points for 39 CO2-IL systems and 664 data points for 14 H2S-ILsystems were collected to develop the models with acceptable generality. The input parameters of the models are temperature, pressure, molecular weight of IL and several structural related parameters of ILs. The performance of the developed models was evaluated by using statistical quality measure approaches. Moreover, the predictions of the developed models are compared with the predictions of a thermodynamic model based on Peng-Robinson equation of state (EoS). Results show that the developed models provide accurate predictions with reasonable errors. However, the CSA-LSSVM model provides better predictions for both CO2-IL and H2S-IL systems with average absolute relative deviation values of 1.97% and 0.13%, respectively. Moreover, the predictions of the developed models are found better and effective than the predictions of the thermodynamic model. Results of this work also show that the solubility of CO2 and H2S in ILs could be well correlated by structural related parameters of ILs.

Carrier concentration effect and other structure-related parameters on lattice thermal conductivity of Si nanowires

Lattice thermal conductivity (LTC) of Si bulk and nanowires (NWs) with diameter 22, 37, 50, 56, 98 and 115 nm was investigated in the temperature range 3–300 K using a modified Callaway model that contains both longitudinal and transverse modes. Using proper equations, mean bond length, lattice parameter, unit cell volume, mass density, melting temperature, longitudinal and transverse Debye temperature and group velocity for all transverse and longitudinal modes were calculated for each NW diameter mentioned. Surface roughness, Gruneisen parameter and impurity were used as adjustable parameters to fit theoretical results with experimental curves. In addition, values of electron concentration and dislocation density were determined. There are some phonon scattering mechanisms assumed, which are Umklapp and normal processes, imperfections, phonon confinement, NW boundaries, electrons scattering and dislocation. Dislocation density less than 10 $$^{{14}}$$ m $$^{{-2}}$$ for NWs and 10 $$^{{12}}$$ m $$^{{-2}}$$ for bulk has no effect on LTC. Also, electron concentration less than 10 $$^{{22}}$$ m $$^{{-3}}$$ for NWs and 10 $$^{{16}}$$ m $$^{{-3}}$$ for the bulk has no effect. On increasing dislocation density and electron concentration, LTC comparably decreases.

Permissible range of model parameters for natural fine-grained materials

This paper presents a three-dimensional constitutive model for natural clay that includes creep, anisotropy and structure, as well as a theoretical means to estimate the range for anisotropy- and structure-related parameters, as needed for parameter optimisation. Creep-SCLAY1S is an extension of the Creep-SCLAY1 model proposed by Sivasithamparam et al. (Comput Geotech 69:46–57, 2015) which includes the effects of bonding and destructuration. The model needs 14 model parameters, of which five are similar to those used in the modified Cam–Clay model. A method is developed to quantify the range for the three parameters related to structure and anisotropy that cannot be derived directly from experimental data. The theoretically derived range compares favourably with the values found in the literature. As a result, the model now can be used with more confidence, enabling sensitivity analysis and systematic parameter derivation with optimisation techniques.

Understanding the underlying mechanism of the enhanced performance of Si doped LiNi0.5Mn0.5-xSixO2 cathode material

Si with x=0.000, 0.015, 0.030, and 0.050 is successfully doped into layered LiNi0.5Mn0.5-xSixO2 using a sol − gel method. Si doping results in a decrease in lattice constant, Li/Ni mixing, stress, and size of primary particles. Si is distributed at the Mn site probably nonuniformly to cause two different states of Si4+. Si doping exerts no influence on the 2p bands of Ni2+, and however gives rise to a slight splitting of 2p3/2 band of Mn4+, and tends to increase the diffusion activation energy of Li+. The optimum performance is achieved for LiNi0.5Mn0.5-xSixO2 with x=0.015 which has the highest BET surface area. Detailed analysis of structural modifications allows one to conclude that the remarkable alleviation of agglomeration of primary particles other than the optimization of structure related parameters such as the lattice constant, metal − oxygen bond length, ordering, cation mixing, size, and stress is responsible predominantly for the performance improvement. This study suggests that silicon is not an effective dopant for performance improvement of layered LiMO2 simply from the perspective of structural modifications and optimization.

Influence of Cr substitution on Debye-Waller factor and related structural parameters of ZnFe2-xCrxO4 spinels

The influence of Cr3+ ions on the Debye-Waller factor and other related structural parameters of the polycrystalline ZnFe2-xCrxO4 (0.0 ≤ x ≤ 2.0) system was characterized at room temperature using the XRD, TEM, SEM and infrared (FT-IR) spectroscopy tools. X-ray diffraction results confirm the FCC spinel structure. Values of the lattice constant ‘a’ were found to decrease from 8.4370 Å for ZnFe2O4 ferrites to 8.3208 Å for ZnCr2O4 chromates. The structure factors for the (hkl) planes were calculated and used to estimate the intensity of the X-ray diffractions and the cation distributions among the tetrahedral and octahedral sites. The Debye-Waller factors were used to estimate the Debye effective temperatures, the mean square displacements and Debye frequencies of these spinels. The FT-IR spectra were characterized by two main absorption bands υ1 and υ2 in the frequency range of (400–1000) cm−1. These bands are caused by stretching vibrations at the tetrahedral (A) and octahedral (B) sites respectively. The scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs revealed aggregates of stacked grains.

Experimental Investigation of Compressive Behaviour of Pier by Partial Replacement of Metakaolin

Objectives:The main focus of our experimental investigation is to study the behavior of a pier based on variations in compressive strength due to partial replacement of cement with metakaolin in order to attain maximum stiffness and strength, so as to withstand the shear forces, bending moments and other related structural response parameters efficiently. Analysis: The round and rectangular specimens were prepared by replacing cement with metakaolin up to 15%. The samples were tested after 7 and 28 days. Findings: Study reveals that with the replacement of 10% metakaolin in both circular as well as rectangular moulds, there is an increase in the load carrying capacity approximately about 19%, when compared with plain reinforced concrete moulds after 28 days. The most important finding is that the replacement of cement by metakaolin up to 10% helped us to attain higher strength after 7 as well as 28 days hence providing us a simple and efficient method of preventing the pier failure by attaining higher strengths. Improvement/Applications: Based on the test results there is remarkable increase in the load carrying capacity of pier which enhances the rigidity of pier in terms of strength and stiffness.

Study of Beam-Column Junction based on Variations in Concrete Grade at Junction

Objectives: A beam-column joint has to transfer the shear forces, bending moments and other related structural response parameters efficiently. The present paper aims at studying the behavior of beam-column junction based on variations in concrete grade at junction. Analysis: To increase the load carrying capacity of a joint, a higher grade of concrete is used at a joint and also up to 1.5D in the direction of beam from face of column, to shift or relocate the plastic hinge from the interface towards the beam. The different specimens were prepared in a T-shaped mould by changing the grade of concrete at beam-column joint and these samples were tested after 7 and 28 days. Findings: Study reveals that use of M20 or M25 grade of concrete at joint and up to 1.5D (D is the depth of beam) of length of beam (M15 grade of concrete in rest of mould) increases the load carrying capacity approximately to about 20% when compared with M20 or M25 grade of concrete at junction and M15 grade in the remaining mould. The most important finding is that the use of higher grade of concrete at a joint and up to 1.5D of length of beam, shifts the failure away from the beam-column interface Thus, a beam hinging mechanism is achieved which is a ductile type of failure compared to beam-column brittle interface failure and there is approximately 15-30% increase in load carrying capacity, in comparison with higher concrete grade only at a joint core. This is a simple and efficient method of preventing the beam-column joint failure. Improvement/Applications: Based on the test results there is remarkable increase in the load carrying capacity of beam-column joint which enhances the rigidity of beam column joint in terms of strength and stiffness.

Prediction of heat capacities of ionic liquids using chemical structure based networks

Ionic liquids (ILs) have various desired properties which bring them as useful and applicable compounds in different industrial processes. Heat capacity of ILs is one of their main properties which is required in various engineering and design applications. Hence, developing accurate and general models for prediction of this property is important. In this communication, two accurate and general models based on Radial Basis Function Neural Network (RBF-NN) and Multilayer Perceptron Neural Network (MLP-NN) were developed for estimation of heat capacities of ILs. The input parameters of the models are temperature, molecular weight of IL and several structural related parameters for each IL. The models were developed based on 2940 experimental data for 56 ILs. The reliability and accuracy of predictions of the developed models were examined by using statistical and graphical methods as well as comparing the results of the models with outcomes of recently developed literature correlations. Results show that the developed models are accurate and reliable and are superior to literature correlations for predictions of heat capacity of ILs. The average absolute relative deviation of RBF-NN and MLP-NN models for predicted heat capacity data was 0.83% and 1.04% respectively.

Effects of structure-related parameters on the response of concrete-filled double-skin steel tube columns to lateral impact

Concrete-filled double-skin steel tubes (CFDSTs) find increasing use as bridge piers and building columns. This paper treats the impact response of such columns using numerical simulations. The modelling techniques are validated using experimental results to establish the capability of the numerical model to capture the impact response and failure modes of the column. The validated numerical model was used to carry out a parametric study on the effects of several structure-related parameters on the impact response of the CFDST columns. The findings of this paper can be used to develop appropriate design information for CFDST columns under lateral impact loading.

Protein folding prediction

Protein folding is the process that a protein molecule transforms from the linear polymer of peptides to a three-dimensional native structure with specific biological function. By now, the protein folding problem has been studied for more than 50 years and already became a broad and active research field. To answer the 58th question raised by Science in 2005, in this article we briefly reviewed the background and research history of the protein folding problem, and introduced the progresses of protein folding prediction research from four aspects: the protein folding process prediction (protein folding simulation), the folding process related parameter prediction, the protein folding result prediction (protein structure prediction), and the folding result related parameter prediction. The studies on the protein folding problem began in the 60s of 20th century, with the efforts to seek a solution to the paradox that a protein can actually form a native 3D structure in only several seconds but the time scale estimated by a thermodynamic ergodic hypothesis would be longer than the age of universe. Computer simulation is an important approach for protein folding study. The protein models can be classified into 3 categories: lattice model, off-lattice model and all-atom model. The current knowledge about protein folding mechanism is based on the concept of folding funnel on a free-energy landscape, and the current opinion is that the protein folding mechanism is not unique for the whole protein universe and that there may exist a continuum between the two extreme ends of hierarchical folding and nucleation folding scenarios. The hardware for protein folding simulation was becoming more powerful; distributed systems (e.g, Folding@home), special-purpose machines (e.g, ANTON), and GPU-based platforms have been developed for protein folding simulation. Meanwhile, the folding simulation software was continuously enhanced. An important issue in protein folding simulation is to overcome the local energy barrier to find the global energy minimum; several approaches such as replica-exchange, multi-scale modeling and Modeling Employing Limited Data (MELD) were developed to tackle this issue; human intelligence involvement (e.g, “Foldit” Game) is another interesting effort. During the past two decades, the ability of protein folding simulation was continuously rising. For now, the folding simulation for the proteins with dozens of amino acids can reach a time scale of millisecond, while the protein size able to do effective folding simulation is around 100 amino acids. The targets of protein folding simulation have been largely expanded and now include both the in vitro and the in vivo folding such as co-translational folding, chaperone-assistant folding, small-molecule- induced folding and metal-coupled folding. Folding rate and folding type are two important parameters related with the protein folding process and now they can be predicted by statistical and machine-learning approaches based on different levels of structural features such as the topological properties of tertiary structure, the contents of secondary structure and the amino acid frequencies of primary structure. The result of a protein folding process is the formation of a protein structure. According to the hierarchy of structural organization, the protein structure prediction problem includes secondary structure prediction, tertiary structure prediction and quaternary structure prediction. By now, the secondary structure prediction algorithm has experienced five generations and the current accuracy is about 80% for 3-classes prediction. The tertiary structure prediction approaches mainly include two categories: template-based modeling and free modeling, with the former having higher accuracy and the latter having larger application scope. The quaternary structure prediction includes the prediction of complex structure and the prediction of the possibility of protein-protein interaction, and these predictions can be performed based on protein 3D structure or merely amino acid sequence. Structure related parameter prediction also attracted research interests, including the predictions of protein structural classes, secondary structure contents, disordered regions, solvent accessible surface region and the amino acid contacting pairs in the interface of protein-protein interaction. In the end, some possible development directions worth noticing in the future of protein folding research were suggested and they are: the coupling between protein folding and binding, the fusion of protein folding research with systems biology and the application of deep-learning techniques in the field of protein folding prediction.

Application of mechanical measurement in assessment of neck pain and manual therapy

Manual therapy is one of the effective methods in treating neck pain. It has certain advantages in the short term to ease the symptoms of neck pain. In recent years, using different mechanical sensors and imaging equipment with computer software, the researchers found the difference of cervical activity between health adult and patients with neck pain. They also analyzed the kinematics, magnitude of force, stress and strain of the related structure and other mechanical parameters during cervical manipulation. These biomechanical researches revealed the functional anomaly caused by neck pain, reflect the safety of cervical manipulation, explain the abnormal stress of neck pain and the adjusting role of manipulation. Relatively speaking, these studies are too basic, and their analysis also are limited for the stress and strain about internal tissue. Study to aim directly at above problems will have important significance in understanding neck pain and standardizing manipulation therapy.

Effect of sea level rise on nearshore significant waves and coastal structures

In this paper, the method to assess the impact of sea level rise under regular waves, as proposed by Townend (1994), is extended to irregular waves in order to estimate the changes in nearshore significant waves and the parameters related to hydraulic performance and stability of inclined coastal structures. The relative changes in wavelength, refraction coefficient, shoaling coefficient, and wave height for significant waves are presented as functions of the relative change in water depth. The calculated relative changes in wave characteristics are then used to estimate the effect of sea level rise on coastal structures by calculating the relative changes in wave run-up height, overtopping discharge, crest freeboard, and armor weight of the structures. The relative changes in wave characteristics are expressed as functions of relative water depth and deepwater wave angle or wave steepness. The relative changes in the structure-related parameters are expressed as functions of the relative change in wave height and the wave height and crest freeboard before the sea level rise.

Retina-like sensor based on a lens array with a large field of view.

This paper puts forward a retina-like sensor based on a lens array, which can be used in conventional optical systems. This sensor achieves log-polar mapping by dividing the imaging optical system's image plane using a lens array. In this paper the mathematical model has been set up with the relative structural parameters. Also, the simulation experiments and parameter analysis have been discussed to verify the reliability of this system. From the experiment results, it can be seen that this sensor realized the log-polar mapping with the transformed image output. Each lens corresponded to a circular region in the image plane with no crossover between different fields of view of adjacent lenses. When the number of rings changed, the relative error did not significantly change, and this error could be reduced to 1% when the number of lenses in each ring was increased. The work widely enlarged the application of this kind of sensor, which will lay a theoretical foundation for retina-like sensors.