Combination Force Research Articles

Uncertainty analysis of the molecular dynamics method for simulations of sulfonated poly ether ether ketone proton exchange membrane in fuel cells

Molecular dynamics (MD) simulations have become a standard tool for logical interpretation of proton exchange membrane (PEM) performance. However, it has several parameters that affect the accuracy and reliability of results. Considering the most prevalent, we explore uncertainty analysis of chain configurations, thermostats, ensembles, and force fields for simulations of sulfonated poly ether ether ketone PEM. In order to choose proper chains and monomers number, total solubility parameter and density are evaluated. The mean square displacement of proton and temperature variances are determined, revealing the Berendsen thermostat as appropriate temperature controllers (11 Å2 and 9.478 K2, respectively). After choosing proper ensembles combination, COMPASSⅡ, COMPASSⅢ, and DREIDING force fields are compared, using glass transition temperature (Tg) and proton conductivity. Tg values of DRIEDING model (461 K) are in good agreement with experimental results (458 K), while conductivities of COMPASSⅢ model show better consistency (16.6 mS.cm-1 vs. 18.0 mS.cm-1). Therefore, parameters selection depends on the target simulation analysis.

A novel technology to reduce astringency of tea polyphenols extract and its mechanism

ObjectiveTea polyphenols are natural extracts used widely throughout the world. However, the severe astringency of tea polyphenols has reduced patient compliance. Based on the analysis of the formation mechanism of astringency, this paper hopes to propose a new method to control the astringency of tea polyphenols and improve patient compliance without changing its effect. MethodsArtificial saliva was used to prepare the tea polyphenols solution with different pH, using β-casein to imitate salivary protein, and preparing 1.2 mg/mL β-casein solution. A fluorescence quenching test was used to study the interaction between tea polyphenols and β-casein, combined with the stability test results of the compound, we can choose the pH with weak binding but good stability as the best pH for masking astringency. The taste-masking tablets were prepared under the best pH conditions, and the Xinnaojian Original Tablets were prepared according to the conventional preparation method. The disintegration time limit and solubility were tested respectively. The astringency of Xinnaojian original tablets and taste-masking tablets was evaluated by visual analogue scale (VAS). ResultsThe result of the fluorescence quenching test prompted that the combination force was the weakest when the pH was 4.9. Further synchronous fluorescence analysis showed that an increase in pH resulted in a decrease of the binding sites between tea polyphenols and β-casein, and this decrease was closely related to changes in tryptophan residues in β-casein. Both original and taste-masking Xinnaojian Tablets were prepared. Volunteers’ VAS scores illustrated that the astringency improved significantly with the masking tablets (P < 0.05). ConclusionThis pH-adjusting masking treatment had little effect on the recovery of polyphenols from the tablets or the dissolution of the tablets. This study provides a novel and feasible astringency masking technology for tea polyphenols and its preparation.

A sensitive and label-free sensor for melamine and iodide by target-regulating the formation of G-quadruplex

In this study, a novel, sensitive and label-free method was developed for melamine and iodide (I−) detection by target-regulating the formation of G-quadruplex structure. This assay was based on two basic phenomena: first, melamine could bind to thymine (T) through hydrogen bond to form thymine-melamine-thymine (T-M-T) hairpin structure. Second, combination force between mercury ions (Hg2+) and I− was much stronger than that between Hg2+ and thymine, therefore, I− could combine Hg2+ from the thymine-Hg2+-thymine (T-Hg2+-T) hairpin structure. A T-rich single-strand DNA sequence was designed for the two targets detection, which can associate with N-methyl mesoporphyrin IX (NMM) and K+ to form G-quadruplex-NMM complex, producing a strong fluorescence signal. The concentration of free probe DNA was proportional to the amount of melamine or I−, enabling convert the target reaction events into detectable signal of G-quadruplex-NMM by fluorescence spectrometer. Under the optimized conditions, the limits of detections (LODs) were 0.08 nM and 4.6 nM for melamine and I−, respectively, which was comparable to that of other melamine and I− assays. The relative standard deviations (RSDs) (n = 7) were 1.8% and 0.3%, respectively. Besides, melamine and I− in real samples could be detected with satisfactory results. The proposed method retains several unique advantages, including simple, sensitive and selective for label-free analysis.

Assessment of Binding Interaction between Bovine Lactoferrin and Tetracycline Hydrochloride: Multi-Spectroscopic Analyses and Molecular Modeling.

In this paper, the interaction between bovine lactoferrin (bLf) and tetracycline hydrochloride (TCH) was researched by microscale thermophoresis (MST), multi-spectroscopic methods, and molecular docking techniques. Normal fluorescence results showed that TCH effectively quenched the intrinsic fluorescence of bLf via static quenching. Moreover, MST confirmed that the combination force between bLf and TCH was very strong. Thermodynamic parameters and molecular docking further revealed that electrostatic forces, van der Waals, and hydrogen bonding forces played vital roles in the interaction between bLf and TCH. The binding distance and energy transfer efficiency between TCH and bLf were 2.81 nm and 0.053, respectively. Moreover, the results of circular dichroism spectra (CD), ultraviolet visible (UV-vis) absorption spectra, fluorescence Excitation-Emission Matrix (EEM) spectra, and molecular docking verified bLf indeed combined with TCH, and caused the changes of conformation of bLf. The influence of TCH on the functional changes of the protein was studied through the analysis of the change of the bLf surface hydrophobicity and research of the binding forces between bLf and iron ion. These results indicated that change in the structure and function of bLf were due to the interaction between bLf and TCH.

Orthodontic Force and Tooth Movement With and Without Occlusal Loads: 3D Analysis Using Finite Element Method

Background: Occlusal loads are always present though not widely considered in orthodontic treatments. Applied force systems are analyzed in detail and taught but their interaction with occlusal force is oftentimes ignored. Numeric evaluation of this combination by finite element method is the main goal of this research. Objectives: The present study has implemented FEA to investigate the effect of orthodontic force application on the tooth-periodontium-alveolar bone system. Materials and Methods: A 3D model of a lower premolar was designed. The model contained cortical and spongy bone, PDL, and tooth. A 1.73 N force decomposed to 1 N in each plane axis was applied as a random levelling and aligning force to assess the von Mises stress produced at the mesial aspect of the PDL from cervical down to the apical area. At the second phase a 200-Newton intruding force vector was applied simulating the occlusal force. The effects of the combination force system were evaluated in the same area of the PDL. Results: The maximum finding of von Mises for both stages were in found in the cervical area. This was almost 0.267 MPa for the first stage and 2.27 MPa for the second stage. Conclusions: Our findings show that the co-existence of heavy occlusal forces due to clenching or bruxism in our tooth-periodontium-orthodontic force system has a significant influence on the magnitude and location of the high stress areas.

The Preparation and Apply of Ni-W-P Alloy Coating for Electricity-Control Equipment

The treatment technics for substrate was researched and improved by experimentations, the technics and additive research of plating for forming ornamental and functional multicomponents alloy was carried out completely, the optimum technics of plating multicomponents alloy was been found. The coatings made by optimum technics were with excellent corrosion-resistance ,wear-resistance, oxidation-resistance and with a smooth, fine, shining surface. It was proved that the 8.9% phosphorus in the coating and the coating was amorphous crystal by determinations. And it was found that the combination force between the substrate and the coating was vary good and the properties of coating to resist corrosion and abrasion were much better than that of Ni-P alloy through the tests.The coating was finery in ornamentally also.

KSLV-I 페이로드 페어링 구조시험

Payload fairing(PLF) protects satellites and related equipment from the external environment. They are separated before the satellite separation. Payload fairing made of composite sandwich materials due to their considerable bending stiffness and strength-to-weight ratio. Payload fairing have compression, shear and bending load during the flight. In this study, To check the strength of PLF and connected part, structural test of PLF accomplished using an actuator and a fixture. Purpose of structural test is to verify the strength of PLF in force of separation spring and combination structural load applied. Test result shows that the PLF have an acceptable margin of safety for the combination structural load and force of separation spring.

The Preparation and Application of Special Performance Ornamental Alloy Coating on Plastic Substrate

The electroless plating technics of copper on plastic substrate was researched, and on this basis, the Ni-W-P alloy plating technics on aforementioned plastic substrate was researched. The optimum electroless plating technics, plating technics and bath were found. The coating made in optimum technics was excellent in corrosion-resistance, wear-resistance, oxidation-resistance, and with a smooth, fine, shining surface. It was proved that the 8.1% phosphorus in the coating and the coating was amorphous crystal by determinations, the combination force between the substrate and the coating was very good, the properties of coating to resist corrosion and abrasion were 4 times better than that of Ni-P alloy by the tests. The coating was finery in ornamentally also.

The Study on Preparation and Apply of Ni-Co-P Alloy Coating

The study on combinatorial additives and plating technics for preparation and apply Ni-Co-P alloy coating was carried out completely, and the Ni-Co-P alloy with functional, corrosion-resistance and ornamental multicomponents was found, the optimum technics of plating multicomponents alloy was been found. The coating made in optimum technics was good in corrosion-resistance and wear-resistance, and with a smooth, fine, shining surface. It was proved by determinations that the 8.2% phosphorus in the coating and the coating was amorphous crystal. It was found that the combination force between the substrate and coating was very good, the corrosion-resistance and abrasion-resistance of coating were much better than that of Ni-P alloy according to the examination, the Ni-Co-P alloy coating with special character which were good magnetic properties and finery in ornamentally also.

Electrorecrystallization of intermetallic compound in the Sn0.7Cu solder joint

The electrorecrystallization, recrystallization driven by electrical current stressing, of Cu6Sn5 intermetallic compound occurs in a Sn0.7Cu flip chip solder bump. The Cu6Sn5 dissolves in Sn0.7Cu at 1.0 × 104 A/cm2 of current stressing under 150 °C. The Cu flux in the solder joint, driven by the combination force of thermal gradient and electromigration, flows toward the cold side of the solder joint. The segregation of Cu results in recrystallization and thus redistribution of IMC at the cold side of the solder joint after current stops.

Preparation of Z-Pin from Different Resin and Evaluation of Interlaminar Reinforcement Effect by Pullout Test

A specific type of bismaleimide resin (BMI) was synthesized and a kind of epoxy resin was formulated to prepare Z-pins reinforced by T300 carbon fiber with diameters of 0.3 mm and 0.5 mm, respectively. Glass transition temperature (Tg) was measured by dynamic mechanical thermal analysis (DMTA) and interlaminar shear strength of Z-pins was tested by short beam shear method. The combination force between Z-pins and laminates was characterized by a special pullout test. The adhesion force/maximum pullout force per unit area between Z-pins and laminates was compared and the combination forces between the Z-pins and laminates were characterized. The results showed that Z-pins based on BMI resin exhibited higher interlaminar reinforcement effect toward T700/5429 composite, concluding that co-bonding between Z-pins and prepreg plays an important role in reinforcing the laminated composites.

Reactive Ability and Bong Strength Analysis on Al(OH)&lt;sub&gt;3&lt;/sub&gt; Crystals with Three Different Crystalline

The crystal structure models of three kinds of different Al(OH)3 crystals, which are gibbsite, bayerite and nordstradite, are built respectively according to the corresponding experimental crystal lattice. Geometry optimizations are implemented by CASTEP program module using general gradient approximation (GGA) and local density approximation (LDA) methods respectively based on density functional theory (DFT). Total energy, electronic structure, atomic and bond populations are also calculated. The calculation results of total energy indicate that gibbsite is steadier than the other two from the point of view of energy, and the effect of basis set of GGA-PW91 is highest. At the same time, energy bond structure and density of states calculated at GGA-PW91 and LDA-CA-PZ levels show that the different of energy gap ΔE (ELUMO-EHOMO) at the first group of BZ is not obvious, and that the highest value of ΔE of gibbsite is more lower than the other two Al(OH)3 crystals. It may be likely to say that gibbsite may be more active than the other two crystals. According to the analysis of populations, it can be found that bond populations value of H-O and Al-O bonds of gibbsite is smallest in three different Al(OH)3 crystals, it is to say that the combination force of H-O and Al-O bonds of gibbsite is smallest and gibbsite may be more easier to be calcined theoretically.

Influence of assembly procedure and material combination on the strength of the taper connection at the head–neck junction of modular hip endoprostheses

BackgroundA stable fixation between femoral head and endoprosthesis taper is necessary to prevent relative motions and corrosion at the taper junction. Although the importance of the component assembly has been recognised, no definitive instructions are available. The purpose of this study was to assess the influence of assembly force, assembly tool and number of hammer strokes on the taper junction strength of various material combinations. MethodsCo–Cr29–Mo (n=10) and Ti–6Al–4V (n=10) neck tapers were assembled with Co–Cr and Al2O3 ceramic heads either by push-on or by impaction with single or multiple hammer blows. The strength of the taper-head connection was evaluated by measuring the head pull-off forces according to ISO 7206-10 and the turn-off moment capacity. FindingsThe taper strength linearly increased with assembly forces (P<0.001). Co–Cr heads combined with Co–Cr tapers showed significantly lower pull-off forces and turn-off moments than the combination with Ti tapers (0.001<P<0.025). Multiple impaction did not increase taper strength (0.063 <P<0.995). Ceramic and Co–Cr heads showed similar fixation patterns on Ti tapers. Turn-off moments varied between 6Nm and 19Nm, dependent on material combination and assembly force. InterpretationIt is suggested that sufficient head–taper junction strength in all bearing conditions is achieved by impaction forces of at least 4kN. A single impact is sufficient to achieve fixation. Special attention should be paid to the assembly of Co–Cr heads on Co–Cr tapers.

Study on the preparation of a multicomponents alloy coating with special properties

The treatment technics for substrate was researched and improved by experimentations, the technics and additive research of plating for forming ornamental and functional multicomponents alloy was carried out completely, the optimum technics of plating multi-components alloy was been found. The coatings made by optimum technics were excellent in corrosion-resistance, wear-resistance and oxidation-resistance, and also has a smooth, fine, shining surface. It was proved that phosphorus content in the coating is 8.4% by determinations, the coating is amorphous crystal. The properties of Ni-W-P coating were test, the result shown that the combination force between the substrate and the coating was very good, the properties of coating to resist corrosion and abrasion were much better than that of Ni-P alloy by the tests. And the coating was finery in ornamentally also.

Preparation of novel bilayer hydrogels by combination of irradiation and freeze–thawing and their physical and biological properties

AbstractBACKGROUND: Hydrogels made by irradiation or freeze–thawing often exhibit poor mechanical strength; therefore we investigated a novel synthetic method to circumvent this detrimental effect. We report a series of novel bilayer poly(vinyl alcohol) (PVA)/water‐soluble chitosan (ws‐chitosan)/glycerol hydrogels prepared by a combination of irradiation and freeze–thawing. Scanning electron microscopy morphology, swelling behavior, mechanical strength, elongation at break, PVA dissolution behavior and bovine serum albumin (BSA) release profile of the bilayer hydrogels were compared with those of hydrogels made by irradiation and freeze–thawing followed by irradiation. The cytotoxicity of the bilayer hydrogels was studied using a tetrazolium salt (MTT) assay.RESULTS: The novel bilayer hydrogels contain one layer made by freeze–thawing followed by irradiation and the other layer made by irradiation. The preparation method provides the two layers with good combination force in the wet state. However, the two layers are not combined very well in the freeze‐dried state due to the difference in microstructure. The bilayer hydrogels have large swelling capacity and good mechanical strength, and these properties can be varied by changing freeze–thawing cycles, irradiation doses and the relative thickness of the two layers. The PVA and BSA release behaviors show that the bilayer hydrogels have a small amount of dissolved PVA and can prolong the BSA release time. The MTT assay shows that extracts of the bilayer hydrogels are non‐toxic towards L929 mouse fibroblasts.CONCLUSION: The novel bilayer hydrogels prepared in this study show good physical properties with no cytotoxicity, indicating that they are suitable for biomedical applications, such as in wound dressings and drug delivery devices. Copyright © 2009 Society of Chemical Industry

下がく部骨移植の臨床的研究 ＶＩＩＩ 移植骨片付Ｄ‐Ｐ皮弁による下がく骨再建の２例

Secondary mandibular reconstructions using osteocutaneous flaps were performed in a 27-and a 64-year-old male patients, who had a mandibular defect with contructure of scar in the surrounding tissue. Primarily, in the first case, an iliac graft and in the second case, a 7th rib graft were wrapped when making a deltopectoral flap, respectively. Secondarily, each osteocutaneous flap was transplanted to the defect for reconstruction of the mandible following deepithelization. In the iliac graft, the mandibular reconstruction was successful, and in the rib graft, it resulted in a pseudoarthrosis due to postoperative infetion and salivary fistula from injury to the parotis gland during operation.The previous two experiences suggest to us the following: 1) Bone graft wrapped in the deltopectoral flap may maintain blood supply and tolerate postoperative infection. 2) The union between the cutaneous flap and bone graft was stronger in the iliac graft than in the rib one. Because the surface of the rib is flat and covered by the cortical bone, morphologically, its combination force is inferior. 3) This technique is disadvantageous, because it takes much time owing to delays, but it has an advantage of minor damage by operation. 4) For the purpose of fixation of the graft and the mandibular stump, utilization of metal plates or intermaxillary fixation in a term should be performed.