DENSITY, EQUILIBRIUM HEAT OF FUSION AND EQUILIBRIUM MELTING TEMPERATURE OF NYLON 1010

The density, equilibrium heat of fusion and equilibrium melting temperature of Nylon 1010 were determined by means of infrared spectrum, differential scanning calorimetry, wide angle X-ray diffraction and density measurement techniques. According to Starkweatber' s method crystalline density ρ_c and amorphous density ρ_a were estimated to be 1.098 and 1.003 g/cm^3 respectively by extrapolating the straight lines of the IR absorbanee against density to zero intensity. Owing to the less intense in absorbance and less sensitive to the change in crystallinity of the amorphors band the thus obtained ρ_c was too low in value. Thereby the value of the ratio ρ_c /ρ_a is far less than generally accepted mean value for most crystalline polymers. Accordingly, traditional X-ray diffraction method was used through determining thc crystalline dimension(a=4.9, b=5.4, c=27.8, α=49° β=77.0°, γ=63.5°), and a rather correct value of ρ_c or the crystal density 1.13 g/cm^3 was obtained. The equilibrium heat of fusion △H_m^0 was estimated to be 244.0 J/g piotting △H_m 's of specimens with different crystallinity against their corre sponding specific volumes_(sp), and extrapolating to completely crystalline condition (_(sp)~c= 1/ρ_c) As to the equilibrium melting temperature T_m^0, because of the easiness of recrystallization of melt crystallized Nylon 1010 specimen, the well-known Hoffman's T_m-T_c method failed in determining this value and an usually rarely used Kamide double extrapolation method was adopted. The so obtained value of T_m^0 487 seems to be fairly reasonable.

Study on Carburizing and Temperature Rising of the Semi-Steel Melt with Plasma Heating

Experiments were carried out on carburizing and temperature rising of the semi steel melt in a plasma induction furnace.Influence of many factors, such as power supply mode,position of the plasma torch and bottom blown gas stirring,on heating efficiency and melt temperature distribution was studied. Melt temperature could be effectively controlled by plasma heating,and carbon content of semi steel melt increased from 1.92 % to 4.58 %, and the utilization rate of carbon reached up to 61.57 % during carburizing of the melt.

Metallurgical properties of CaO–SiO_(2)–Al_(2)O_(3)–4.6wt%MgO–Fe_(2)O_(3)slag system pertaining to spent automotive catalyst smelting

The metallurgical properties of the CaO–SiO_(2)–Al_(2)O_(3)–4.6wt%Mg O–Fe_(2)O_(3)slag system,formed by the co-treatment process of spent automotive catalyst(SAC)and copper-bearing electroplating sludge(CBES),were studied systematically in this paper.The slag structure,melting temperature,and viscous characteristics were investigated by Fourier transform infrared(FTIR)spectroscopy,Raman spectroscopy,Fact Sage calculation,and viscosity measurements.Experimental results show that the increase of Fe_(2)O_(3)content(3.8wt%–16.6wt%),the mass ratio of CaO/SiO_(2)(m(CaO)/m(SiO_(2)),0.5–1.3),and the mass ratio of SiO_(2)/Al_(2)O_(3)(m(SiO_(2))/m(Al_(2)O_(3)),1.0–5.0)can promote the depolymerization of silicate network,and the presence of a large amount of Fe_(2)O_(3)in form of tetrahedral and octahedral units ensures the charge compensation of Al^(3+)ions and makes Al_(2)O_(3)only behave as an acid oxide.Thermodynamic calculation and viscosity measurements show that with the increase of Fe_(2)O_(3)content,m(Ca O)/m(SiO_(2)),and m(SiO_(2))/m(Al_(2)O_(3)),the depolymerization of silicate network structure and low-melting-point phase transformation first occur within the slag,leading to the decrease in melting point and viscosity of the slag,while further increase causes the formation of high-melting-point phase and a resultant re-increase in viscosity and melting point.Based on experimental analysis,the preferred slag composition with low polymerization degree,viscosity,and melting point is as follows:Fe_(2)O_(3)content of 10.2wt%–13.4wt%,m(CaO)/m(SiO_(2))of 0.7–0.9 and m(SiO_(2))/m(Al_(2)O_(3))of 3.0–4.0.This work provides a theoretical support for slag design in co-smelting process of SAC and CBES.

Methods and parameters of melting curve analysis for identification of Leishmania species:A scoping review

Leishmaniasis is a set of diseases with a worldwide distribution that affects mainly economically underprivileged populations in developing countries. It has a major impact on public health, with a global cost of billions of dollars per year. The treatment and control of leishmaniasis vary according to the Leishmania species involved, which require reliable methods for species identification. Since most of the currently used methods have limitations, there is a need for assays that allow rapid, precise identification of the offending species. Real-time polymerase chain reactions in conjunction with dissociation curve analysis have been used to detect differences in the DNA composition of selected genes of Leishmania spp. Kinetoplast DNA is the main molecular target used because of its high copy number per parasite, but other targets have also been studied. As part of an effort to establish melting temperature standards for each target gene, we have reviewed the pertinent literature available in public databases, including Pub Med, Web of Science, Sci ELO and LILACS, using the keywords "Leishmania", "leishmaniasis", "realtime PCR", "melting temperature", and "melting curve", alone or in combination. After applying eligibility criteria, 27 articles were selected for analysis. A considerable variation in the methodologies analyzed was found regarding molecular targets, standardization of the methods, reproducibility and specificity. Because of this, statistical analysis was not performed. In most cases, the methods were able to differentiate the parasite at the subgenus level or few species regardless of the target chosen.

STUDY ON CONTACTING MELTING AND ANTI-SKID TECHNOLOGY FOR A TIRE TRACTION ON ICE

Theoretical analyses and experimental studies of the mechanisms of melting film formation are performed. The results show that frictional heating is the dominant mechanism because temperature behaves in the manner predicted by the theory of frictional heating. A study of the active technology for anti-skid is also made. Conclusions indicate that adjusting tire pneumatic pressure can improve the control stability and the travelling safety of an ice-automobile.

Theoretical study of a melting curve for tin

The melting curve of Sn has been calculated using the dislocation-mediated melting model with the‘zone-linking method＇.The results are in good agreement with the experimental data.According to our calculation,the melting temperature of γ-Sn at zero pressure is about 436 K obtained by the extrapolation of the method from the triple point of Sn.The results show that this calculation method is better than other theoretical methods for predicting the melting curve of polymorphic material Sn.

Molecular dynamics of MgSiO3 perovskite melting

The melting curve of MgSiO3 perovskite is simulated using molecular dynamics simulations method at high pressure. It is shown that the simulated equation of state of MgSiO3 perovskite is very successful in reproducing accurately the experimental data. The pressure dependence of the simulated melting temperature of MgSiO3 perovskite reproduces the stability of the orthorhombic perovskite phase up to high pressure of 130GPa at ambient temperature, consistent with the theoretical data of the other calculations. It is shown that its transformation to the cubic phase and melting at high pressure and high temperature are in agreement with recent experiments.

Microstructures and properties of low-melting-point AI-Cu-Si filler metals prepared by different technologies

The Al25 Cu6. 5 SiO. 09RE （RE = La and Ce ） and Al25 Cu10. 5 Si2Ni filler metals were prepared by common metal mold casting, copper plate chilling and rapid solidification, respectively. The microstructures and properties of these filler metals were studied. The results show that the as-casting and the corresponding rapid solidification filler metals have the same phases but their microstructures are different. The microstructure of rapid solidification filler metals consists of an α-A1 solid solution, the θ （ Al2 Cu ） intermetaUic compound and an Al-Cu-Si eutectic phase. Compared with the ns-casting filler metal, the melting temperature ranges （△T） of the corresponding copper plate chilling and rapid solidification filler metals decrease and their wettabilities are improved because of the grain refinement and the improvement of composition uniformity. The wetting area of Al25Cu6. 5Si0. 09RE rapid solidification filler metal doubles that of the corresponding as-casting filler metal. It is hopeful that the properties of Al-Cu-Si filler metals will be improved by changing preparation technology.

Immersing Treatment of Steel Plate Surface in Steel-Aluminum Solid to Liquid Bonding

The interfacial status of the steel-aluminum solid to liquid bonding plates (their steel plate surfaces were or were not immersed in flux aqueous solution) were measured by using SEM (Scanning Electron Microscope) and X-ray diffraction . The results showed that the layer of flux (the minimum thickness was 15 μm on the steel plate surface) could protect the steel plate surface from oxidizing effectively at high temperature in solid to liquid bonding. The melt temperatUre of the flux should be lower than 580 ℃ so that it could be melted and removed completely. No. 1 flux (patent product made by the author) made up of halogeindes could also force liquid aluminum to infiltrate into steel plate surface and thus the interfacial shear strength of the bonding plate was rather large.

Effects of Ga and In on the properties of cadmium-free Ag-Cu-Zn filler metal

Melting temperature, spreadability, mechanical properties and the microstructures of joints brazed with silver-base filler metals including different amounts of Ga and/or In were studied respectively in this paper, and the results show that the melting temperature of the silver-base filler metals is decreased, spreadability of the silver-base filler metals is improved, and the microstructures of silver-base filh, r metals are refined obviously with the addition of Ga and/or In. Using copper and brass plates as base metal and brazing with flame method, the mechanical properties of the lap-joint and butt joint were also examined and analyzed respectively, and the results indicate that the fracture position of two kinds of brazed joints occurred on the base metal, except for the lap-joint of brass, which shows better mechanical properties of the joints brazed with the silver- based filler metals including Ga. For the lap-joint of brass, the tensile strength gradually increased with the increase of Ga content, while the addition of In has little effect on mechanical properties. It is also found that the best comprehensive properties of cadmium-free Ag-Cu-Zn filler metals are obtained when Ga content is about 3.0 wt. % and In content is between 1.5 wt. % and 2. 0 wt. %.

Effect of B_2O_3 on Melting Temperature of CaO-Based Ladle Refining Slag

B2O3 is selected as fluxing agent of CaO-based ladle refining slag to decrease the melting temperature as well as to improve the speed of slag forming and the refining efficiency. The effects of B2O3 on the melting temperature of two series of refining slags including the low basicity slags （the mass ratio of CaO/SiO2 is 3--4） and the high basicity slags （the mass ratio of CaO/SiO2 is 5--8.75） were investigated. The slag melting temperature was meas- ured using the hemisphere method. The results indicate that the fluxing action of B2O3 is better than that of CaF2 and A1203. For the CaO-based refining slag with low basicity, the melting temperature is decreased effectively when B2O3 is used to substitute for equal mass of CaF2, Al2O3 and SiO2, respectively. For the CaO-based refining slag with high basicity, when CaF2 is substituted by B2 03, the melting temperature can be decreased remarkably. Espe- cially, when the mass ratios of CaO/Al2O3 and CaO/SiO2 are in the range of 1.1--4.0 and 5.25--8. 0, respectively, the slag melting temperature is lower than 1 300 ℃. Therefore, the 132 03-containing refining slags with high ratios of CaO/Al2O3 and CaO/SiO2 have ultra low melting temperature.

EFFECTS OF Pb COMPOUND ADDITIVES ON THE PROPERTIES OF YBa_2Cu_3O_(7-δ)

The melting temperature and critical transition temperature Tc of YBa2Cu3O7-δ with deferent content additives of PbO and BaPbO3 were studied. When PbO was doped in YBa2Cu3O7-δ, the melting temperature of YBa2Cu3O7-δ was reduced, however its superconductivity was weakened. From the XRD pattern of the sintered mixture of YBa2Cu3O7-δ and PbO, it was known that there was a reaction between YBa2Cu3O7-δ and PbO, and the product was BaPbO3. Hence different contents of BaPbO3 (10mass%, 20mass% and 30mass%) were added in YBa2Cu3O7-δ. It was proved that there were no reactions between YBa2Cu3O7-δ and BaPbO3. And the superconductivity of the mixtures was much better than that of the samples with PbO additive.

Effects of B_2O_3 and CaF_2 on Melting Temperatures of CaO-SiO_2-Fe_2O_3 System Fluxes

Fluorite is widely employed as fluxing agent in metallurgy flux , which inevitably leads to serious fluorine pollution.B2O3 is employed as fluxing agent of CaO-SiO2-Fe2O3steelmaking fluxes to substitute for CaF2.The effects of B2O3 and CaF2 on the melting properties of this system were investigated.The melting temperatures of fluxes including softening temperature （Ts）, hemispherical temperature （Th）, and flow temperature （Tf） were measured using the hemisphere method.The results indicate that the fluxing effect of B2O3is more significant than that of CaF2 .When the addition amount of B2O3 （mass percent） exceeds 6% , the melting temperatures of fluxes including Ts , Th and Tf are decreased lower than 1 300℃.The basicity of fluxes has a significant effect on the melting temperature , and the melting temperatures of the fluxes increase with the increase of fluxes basicity.However , when B2O3 is used as fluxing agent , the melting temperature changes little with the basicity increasing from 2.5 to 5.0. These characteristics are suitable for steelmaking process.Moreover , Fe2O3 has an important fluxing effect on this CaO-based steelmaking fluxes.This indicates that the fluxes system is suitable for steelmaking process.

Influences of Ag and Au Additions on Structure and Tensile Strength of Sn-5Sb Lead Free Solder Alloy

It is important, for electronic application, to decrease the melting point of Sn-5Sb solder alloy because it is relatively high as compared with the most popular eutectic Pb-Sn solder alloy. Adding Au or Ag can decrease the onset melting temperature （233℃） of this alloy to 203,5℃ and 216℃, respectively. The results indicate that the Sn-5Sb-i.5Au alloy has very good ultimate tensile strength （UTS）, ductility, and fusion heat, which are better than both those of the Sn-5Sb-3.SAg and Sn-5Sb alloys. The formation of intermetallic compounds （IMCs） AuSn4 and Ag3Sn enhanced the SbSn precipitates in the solidification microstructure microstructure stability, while retained the formation of thus significantly improved the strength and ductility For all alloys, both UTS and yield stress （σy） increase with increasing strain rate and decrease with increasing temperature in tensile tests, but changes of ductility are generally small with inconsistent trends.

Novel and durable composite phase change thermal energy storage materials with controllable melting temperature

The development of high temperature phase change materials(PCMs)with great comprehensive performance is significant in the future thermal energy storage system.In this study,novel and durable Al-Si/Al_(2)O_(3)-Al N composite PCMs with controllable melting temperature were successfully synthesized by using pristine Al powder as raw material and tetraethyl orthosilicate as SiO_(2)source.The Al_(2)O_(3)shell and Al-Si alloy were in-situ produced via the substitution reaction between molten Al and SiO_(2).Importantly,the crack caused by the incomplete encapsulation of the Al_(2)O_(3)shell could repair itself by the nitridation reaction of internal molten Al and thereby forming a highly dense Al_(2)O_(3)-Al N composite shell.The produced dense Al_(2)O_(3)-Al N composite shell could significantly improve the thermal cycling stability of composite PCMs,and thus,the thermal storage density decrease of the Al-Si/Al_(2)O_(3)-Al N(59.8 J/g to77.7 J/g)was far less than that of the Al-Si/Al_(2)O_(3)(118.5 J/g)after 3000 thermal cycles.Moreover,the synthesized Al-Si/Al_(2)O_(3)-Al N still exhibited a controllable melting temperature(571.5-637.9℃),relatively high thermal storage density(105.6-150.7 J/g),great dimensional stability and structural stability after3000 thermal cycles.Hence,the synthesized Al-Si/Al_(2)O_(3)-Al N composite PCMs,as promising preferential thermal energy storage materials,can be stably used in the energy utilization efficiency improvement of various systems for more than 6 years.

Grain reinement limit of commercial pure Al inoculated by Al-Ti-C(B) master alloys

The grain refi nement limits of commercial pure Al inoculated by Al-5Ti-1B, Al-5Ti-0.25C and Al-5Ti-0.3C-0.2B master alloys were studied, and the infl uence of melting temperature on the grain refi ning performance of these three master alloys was investigated using a high scope video microscope(HSVM), a fi eld-emission scanning electron microscope(FESEM), an electron probe micro-analyzer(EPMA) and X–ray diffraction(XRD) method. Results show that there is a grain refi nement limit of commercial pure Al refi ned by these three master alloys; with the same addition level of 1.5% under the present experimental conditions, the grain refi nement limits(smallest average grain size) of commercial pure Al refi ned by Al-5Ti-1B, Al-5Ti-0.25C and Al-5Ti-0.3C-0.2B master alloys are 50 μm, 80 μm and 80 μm, respectively. In addition, with an increase in the melting temperature of the pure Al, the grain refi ning performance of Al-5Ti-1B and Al-5Ti-0.25C master alloys decreases, but the grain refi ning performance of Al-5Ti-0.3C-0.2B changes little.

Detection of Low-abundance Point Mutations by Competitive Strand Assisted Endonuclease Ⅳ Signal Amplification System

Genetic mutations are important molecular biomarkers for cancer diagnosis and surveillance. Therefore, the development of methods for mutation detection characterized with straightforward, highly specific and sensitive to low-level mutations within various sequence contexts is extremely needed. Although some of the currently available methods have shown very encouraging results, their discrimination efficiency is still very low. Herein, we demonstrate a fluorescent probe coupled with blocker and property of melting temperature discrimination, which is able to identify the presence of known or unknown single-base variations at abundances down to 0.1% within 20 min. The discrimination factors between the perfect-match target and single-base mismatched target are determined to be 10.15–38.48. The method is sequence independent, which assures a wide range of application. The new method would be an ideal choice for high-throughput in vitro diagnosis and precise clinical treatment.

Characterization of Cu_3P phase in Sn3.0Ag0.5Cu0.5P/Cu solder joints

This article reports the effects of phosphorus addition on the melting behavior, microstructure, and mechanical properties of Sn3.0Ag0.SCu solder. The melting behavior of the solder alloys was determined by differential scanning calorimetry. The interracial micro- structure and phase composition of solder/Cu joints were studied by scanning electron microscopy and energy dispersive spectrometry. Thermodynamics of Cu-P phase formation at the interface between Sn3.0Ag0.5Cu0.5P solder and the Cu substrate was characterized. The results indicate that P addition into Sn3.0Ag0.5Cu solder can change the microstructure and cause the appearance of rod-like CuaP phase which is distributed randomly in the solder bulk. The Sn3.0Ag0.5Cu0.5P joint shows a mixture of ductile and brittle fracture after shear test- ing. Meanwhile, the solidus temperature of Sn3.0Ag0.5Cu solder is slightly enhanced with P addition.

Melting and Annealing Peak Temperatures of Poly(butylene succinate) on the Same Hoffman-Weeks Plot Parallel to Tm=Tc Line

The crystallization and melting behavior of polymers is of theoretical importance.In this work,poly(butylene succinate)(PBS)was selected as an example to study such behavior at low supercooling via introduction of the extended-chain crystal(ECC)of the same polymer as nucleating agent.The crystallization of PBS with its ECC as nucleating agent in a wide temperature range(90–127°C)and the following melting behavior were studied.It is revealed that the melting point(Tm',for Tc≥113°C)and the annealing peak temperature(Ta',for Tc=90–100°C)show similar asymptotic behavior.Both Tm and Ta approach to a value of ca.3.3°C higher than the corresponding Tc when the crystallization time tc approaches the starting point.That is to say,the Hoffman-Weeks plot is parallel to Tm=Tc line.The crystallization line became parallel to the melting line when PBS was crystallized at Tc higher than 102°C.Based on these results,we propose that the parallel relationship and the intrinsic similarity between the Ta and the Tm observed at the two ends of the Tc range could be attributed to the metastable crystals formed at the beginning of crystallization.

Melting temperature of heavy quarkonium with a holographic potential up to sub-leading order

A calculation of the melting temperatures of heavy quarkonium states with the holographic potential was introduced in a previous work. In this paper, we consider the holographic potential at sub-leading order, which permits finite coupling corrections to be taken into account. It is found that this correction lowers the dissociation temperatures of heavy quarkonium.