Single Melting Point Research Articles

Synthesis, growth and characterization of benzylideneaniline compounds: N-(4-bromobenzylidene)-4-fluoroaniline and N-(4-bromobenzylidene)-4-methoxyaniline

Benzylideneaniline compounds of N-(4-bromobenzylidene)-4-fluoroaniline (BBFA) and N-(4-bromobenzylidene)-4-methoxyaniline (BBMOA) have been synthesized by the condensation reaction process, and single crystals of these compounds are grown at room temperature by the slow evaporation solution growth technique. The compounds BBFA and BBMOA crystallize in the orthorhombic crystal system with different space groups. Placement of hydrogen atoms in BBFA and BBMOA compounds is confirmed from 1H NMR spectral studies. Fourier transform infrared and Raman spectral analyses are employed to study the presence of functional groups in the compounds. Single stage weight loss and melting point of these compounds are determined from thermogravimetric and differential thermal analyses respectively. Nonlinear optical properties are measured using powder second harmonic generation study and open aperture Z-scan technique. Biological activities are studied using the minimum inhibitory concentration method.

Lumefantrine Comparative Study: Single Crystal, Powder X-Ray Diffraction, Hirshfeld Surface, and Thermal Analysis

Lumefantrine is an antimalarial drug and its crystal structure is still absent in the CCDC database. The authors propose a method to obtain the single crystal of this compound and characterize it by single crystal X-ray diffraction (XRD), FTIR, and thermal analysis. Intermolecular interactions are rationalized using the Hirshfeld surface analysis. Ethanol and dichloromethane (1:1 v/v) are used to crystallize the single crystals. The compound crystallizes in the space group P21 with a = 8.7830(11) A, b = 9.4326(7) A, c = 15.8299(16) A, and β = 95.560(9)°, with two molecules in each unit cell. CIF fully simulates the PXRD results. The measured characteristic IR absorption bands belong to the pure material. The single crystal melting point is 128.6 °C (Tonset); the heat of fusion (ΔHfus) is 73.2 J/g, and the thermal degradation process starts at 219 °C, which is confirmed by two steps of the mass loss in the thermogravimetry curve. The CCDC deposit number is 1877120.

Lumefantrine comparative study: single crystal, powder X-ray diffraction, Hirshfeld surface, and thermal analysis

Lumefantrine is an antimalarial drug and its crystal structure is still absent in the CCDC database. The authors propose a method to obtain the single crystal of this compound and characterize it by single crystal X-ray diffraction (XRD), FTIR, and thermal analysis. Intermolecular interactions are rationalized using the Hirshfeld surface analysis. Ethanol and dichloromethane (1:1 v/v) are used to crystallize the single crystals. The compound crystallizes in the space group P21 with a = 8.7830(11) Å, b = 9.4326(7) Å, c = 15.8299(16) Å, and β = 95.560(9)°, with two molecules in each unit cell. CIF fully simulates the PXRD results. The measured characteristic IR absorption bands belong to the pure material. The single crystal melting point is 128.6 °C (Tonset); the heat of fusion (ΔHfus) is 73.2 J/g, and the thermal degradation process starts at 219 °C, which is confirmed by two steps of the mass loss in the thermogravimetry curve. The CCDC deposit number is 1877120.

Solid-State Characterization and Compatibility Studies of Penciclovir, Lysine Hydrochloride, and Pharmaceutical Excipients.

The physical and chemical characterization of the solid-state properties of drugs and excipients is fundamental for planning new formulations and developing new strategies for the treatment of diseases. Techniques such as differential scanning calorimetry, thermogravimetry, X-ray powder diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy are among the most commonly used techniques for these purposes. Penciclovir and lysine are individually used to treat the herpes virus. As such, the development of a formulation containing both drugs may have therapeutic potential. Solid-state characterization showed that both penciclovir and lysine were crystalline materials with melting points at 278.27 °C and 260.91 °C, respectively. Compatibility studies of penciclovir and lysine indicated a possible interaction between these substances, as evidenced by a single melting point at 253.10 °C. The compatibility of several excipients, including ethylenediaminetetraacetic acid, cetostearyl alcohol, sodium lauryl sulphate, di-tert-butyl methyl phenol, liquid petrolatum, methylparaben, nonionic wax, paraffin, propylene glycol, and propylparaben, was evaluated in ternary (penciclovir-lysine-excipient) mixtures (1:1:1, w/w/w) to determine the optimal formulation. The developed formulation was stable under accelerated and ambient conditions, which demonstrated that the interaction between penciclovir and lysine was suitable for the development of a formulation containing both drugs.

Copolymerization of Ethylene and Fluoroalkylnorbornene Using Highly Active ansa‐(Fluorenyl)(amido)titanium‐Based Catalysts

AbstractFluoroalkyl‐functionalized semi‐crystalline polyolefin is obtained by the copolymerization of ethylene and 2‐nonafluorobutyl‐5‐norbornene using ansa‐dimethylsilylene(fluorenyl)(amido)titanium complexes 1a and 1b as catalysts. The copolymerization proceeds with a moderate activity affording a copolymer with high fluorine content up to 5.7 mol% (22 wt%). The melting point decreases from 134 to 82 °C according to the increase of comonomer content. Observation of a single melting point of the copolymer obtained from complex 1b clearly shows the uniform structure of the copolymer, whereas complex 1a gives copolymer with two melting points. The number‐averaged molecular weight of the copolymer reaches over a 105 order of magnitude, which enables the formation of thin film via solvent casting process. Tensile moduli of these copolymers are greatly affected by both molecular weight of the copolymer and comonomer content, and almost comparable with that of low‐density linear polyethylene.

Structural Analysis of Polymeric Copper(II)–Pyrazinamide Complexes Prepared from Two Different Copper(II) Salts

In crystal engineering, the presence of different types of anion may alter the structure of transition metal complexes. Thus, the anions may also govern the properties of the metal complexes. Hereby we reported a structural analysis of polymeric copper(II)-pyrazinamide (pza) complexes prepared from copper(II) sulphate and copper(II) chloride. The complexes were crystallised using a bench-top technique with copper(II):pza molar ratio of 1:2 in a layered H2O-CH3OH solvent at room temperature. Single crystal XRD, ATR-IR and melting point apparatus were used to analyse the structure and characterise the complexes. Single crystal XRD analyses reveals that both complexes, [Cu( µ-pza)(SO4)(H2O)2]n (A) and [Cu(pza)2( µ-Cl)2]n (B) forms a 1D polymeric structure with different metal-ligand connectivity around the octahedral copper centre. The copper centres are also linked by different ligand, namely pyrazinamide in A and chloride in B. Thus, the Cu…Cu distances in both complexes are different, 6.719 Å in A and 3.658 Å in B. Unlike in A, the crystal structure of B has two unique copper centres. In addition, crystal structures of A and B were also compared to closely related copper(II)-pza complexes from published literature. As also observed in many metal complexes, crystal structures of copper(II)-pza complex were affected by the anion of the metal salts used in the reaction, in which the anion also involves in the crystal structures.

Research on forming characteristic of pulsed selective laser melting

To investigate the forming characteristic and obtain a greater process control of the pulsed selective laser melting (P-SLM), the single melting point and single-track and multi-layer block experiments were conducted to investigate the influence of various process parameters on the forming process of P-SLM. A rapid method for the optimization of parameters based on molten pool characterizations is developed. Furthermore, the relationships between the two key process parameters (exposure time, point distance) and the geometric characteristics of single tracks are investigated by linear regression analysis. The research on the surface morphology and the overlapping rate of single-track experiments shows that the value of P-SLM scanning speed is determined by the diameter of single melting point. With relatively high forming efficiency, the highest value of density can be up to 99.99% when the process parameter of exposure time is 80 μs, the point distance is 48 μm, and the hatch space is 80 μm. The yield strength, tensile strength, and elongation of the best sample are 533 Mpa, 647 Mpa, and 40%, respectively, which are higher than that of 316L stainless steel forgings standard (ASTM A473-13).

Melting Diagrams of Adefovir Dipivoxil and Dicarboxylic Acids: An Approach to Assess Cocrystal Compositions

Pharmaceutical cocrystallization is a useful method to regulate the physical properties of active pharmaceutical ingredients (APIs). Since the cocrystals may form in various API/coformer ratios, identification of the cocrystal composition is the critical first step of any further analysis. However, the composition identification is not always unambiguous if cocrystallization is performed in solid state with unsuccessful solution crystallization. Single melting point and some new X-ray diffraction peaks are necessary but not sufficient conditions. In the present study, the use of melting diagrams coupled with the X-ray diffraction data was tested to identify cocrystal compositions. Adefovir dipivoxil (AD) was used as a model API, and succinic acid (SUC), suberic acid (SUB), and glutaric acid (GLU) were coformers. Compositions of AD/SUC and AD/SUB had been previously identified as 2:1 and 1:1, but that of AD/GLU was not unambiguously identified because of the difficulty of solution crystallization. Melting diagrams were constructed with differential scanning calorimetry, and their interpretation was assisted by powder X-ray diffraction. The cocrystal formation was exhibited as new compositions with congruent melting in the phase diagrams. This method correctly indicated the previously known cocrystal compositions of AD/SUC and AD/SUB, and it successfully identified the AD/GLU cocrystal composition as 1:1. The current approach is a simple and useful method to assess the cocrystal compositions when the crystallization is only possible in solid state.

Study on the Shrinkable Behavior of PETG/PET Blending Shrink Film

This paper has studied heat shrinkable behaviors of PETG/PET blending film under different blending ratio. The shrink curve, shrink force, film structure and film seaming property were studied by use of electron stretcher, SEM, shrink force tester, shrinkage tester and so on. The results indicated that PETG/PET blending film had uniform internal structure, single melting point which increased with the PET content, and more than 75% TD shrinkage of PETG/PET blending film was achieved which can be widely used in sleeve labels, but MD shrinkage and shrink force was gradually increased with the increase of PET content inside. At the same time, PETG/PET shrink film had better film stiffness, lower seaming strength, higher density and sharper shrink curve under same shrink temperature.

Phase‐Changeable Fatty Acid Available for Temperature‐Regulated Drug Release

This paper describes a mixture of fatty acids that is available for temperature‐controlled release of drugs. The mixture consists of two fatty acids with different melting points. At a specific composition, the mixture represents a single melting point of 38–40 °C which is slightly above the normal human body temperature. To demonstrate its use in the temperature‐regulated release, this study fabricates fatty acid‐incorporated polymer fibers containing dye‐loaded polymer particles in their core. Below the melting point of the mixture, it will be in a solid state to restrict the passing of dye loaded in the core whereas the dye can be released instantly through the generated pores at a temperature slightly higher than the melting point. The release profiles of the dye can be further manipulated by varying the amount of the mixture contained in the fibers and the composition of the mixture. image

Thermal and Electrical Properties of Sn-Zn-Bi Ternary Soldering Alloys

Sn-Zn based solder is a possible replacement of Pb solder because of its better mechanical properties. The alloys need to be studied and explored to get a usable solder alloy having better properties. In this work, eutectic Sn-9Zn and three Tin-Zinc-Bismuth ternary alloys were prepared and investigated their thermal and electrical properties. Thermo-mechanical Analysis and Differential Thermal Analysis were used to investigate thermal properties. Microstructural study is carried out with Scanning Electron Microscope. The alloys have single melting point. The co-efficient of thermal expansion and co-efficient of thermal contraction varies with alloy composition and temperature range. Electrical conductivity changes with Bi addition.

The Experiment Research on Storage Characteristic of PCM Storage Device by Spheres Piled Encapsulated for Vehicle Waste Heat

For the thermal environment and the warming requirement of Vehicle, carry out experiment study on heat storage characteristic of phase change materials (PCM) encapsulated by Spherical stack. heat storage and release experiment process , changing factors such as medium flow rate and melting point which impact on PCM heat transfer characteristics , melting rate and response time have been analyzed. The results show that within the scope of experiment high medium flow rate is conducive to promote PCM melting rate and heat storage. In the experiments process, high melting point of PCM storage heat grade is high, but the low melting point of PCM is more suitable for vehicle motor, batteries in low temperature waste heat recovery. At the same time, multi-melting point PCM storage device with spheres piled encapsulated delamination mixed stowage was better satisfy the different condition of waste heat recovery and utilization than single melting point of PCM.

Characterization of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) biosynthesized by mixed microbial consortia fed fermented dairy manure

ABSTRACTThe bioplastic poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV), was isolated from a bioreactor using mixed microbial consortia fed volatile fatty acids (VFA), from fermented dairy manure, as the carbon source. The molar fraction of 3‐hydroxyvalerate (3HV) amounted to 0.33 mol mol−1 for two isolated PHBV samples as determined by GC‐MS and 1H‐NMR spectroscopy. The chemical, thermal, and mechanical properties were determined. The PHBVs had relatively high Mw (∼790,000 g mol−1). Only a single glass transition temperature (Tg) and melting point (Tm) were observed. Isolated PHBVs exhibited good flexibility and elongation to break as compared with commercial PHBVs with lower HV. The diad and triad sequence distributions of the monomeric units were determined by 13C‐NMR spectroscopy and followed Bernoullian statistics suggesting that the PHBVs were random. The PHBV sequence distribution was also characterized by electrospray ionization‐mass spectrometry (ESI‐MSn) after partial alkaline hydrolysis to oligomers showing a random 3HV distribution. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40333.

Synthesis and characterization of liquid crystalline copolymers containing poly (ether sulfone) segments

A new block copolymers (BCP) containing poly (ether sulfone) (PES) with different chain lengths and thermotropic liquid crystalline polyester (TLCP) segments were synthesized by high temperature solution polymerization of the constituent monomers of TLCP and PES oligomers terminated with a hydroxyl group. The chemical structure and inherent viscosity of BCP were characterized by Fourier transform infrared spectroscopy, Ubbelohde viscometer and solubility test, respectively. The thermal behavior, liquid crystallinity, texure and thermal stability of liquid crystalline block copolymer were investigated by a variety of experimental techniques including differential scanning calorimetry, polarizing light microscopy and thermogravimetric analysis. BCP showed a single glass transition temperature and melting point but blends of corresponding homopolymers were biphasic. It showed the typical nematic texture above its Tm depending on the composition and good thermal stability. Such block copolymers can be used as compatibilizer or melt viscosity modifying agent for the blends due to their chemical structure similar to the blend partners, respectively.

Effect of Organoclays on Nonisothermal Crystallization Kinetics of Poly (trimethylene terephthalate) Nanocomposite

Non-isothermal crystallization kinetics, melting behavior of virgin PTT and PTT nanocomposites were investigated using differential scanning calorimetry with the Avrami equation. Mechanical properties of PTT/clay nanocomposite is also described with Einstien and Guth model. The rate of crystallization and half time required for crystallization increases with increasing the cooling rate for both virgin PTT and PTT/clay nanocomposites. Virgin PTT shows the double melting behavior which changes to single melting point in prances of C30B nanoclays in the case of PTT/C30B nanocomposites. Incorporation of loading of organoclays increases the activation energy (Ea) in PTT matrix and optimum Ea was observed in PTT/C30B-based system.

Laserspray Ionization Using an Atmospheric Solids Analysis Probe for Sample Introduction

A newly introduced high sensitivity laserspray (LSI) mass spectrometry (MS) method that uses laser ablation of a matrix/analyte mixture at atmospheric pressure (AP) to obtain multiply charged ions from nonvolatile as well as high-mass compounds is now implemented using a simple probe device. The probe used in the LSI approach was originally designed for sample introduction into an AP ionization source using the atmospheric solids analysis probe (ASAP) method. Multiply charged mass spectra of peptides and proteins in 2,5-dihydroxybenzoic acid matrix were readily obtained on two mass spectrometers from different manufacturers with sample introduction using melting point tubes. Here we demonstrate rapid analysis by placing four peptide and protein samples on a single melting point tube. Mass spectra were obtained at high-resolution and using ion mobility spectrometry/MS.

An unusual morphology and crystallization behavior in in situ formed polyphenylene oxide/polyamide 6 blends

Novel polyphenylene oxide/polyamide 6 (PPO/PA6) blends were synthesized via in situ polymerization of e-caprolactam with PPO dissolved in it. The introduction of 10 wt% PPO into PPO/PA6 led to phase inversion of the blends, which was nearly completed by incorporating 15 wt% PPO into the blends. A single crystallization temperature (Tc) of PA6 was detected for PPO/PA6 with 1–4 wt% PPO, while double Tc existed in the blends with 6–15 wt% PPO. After eliminating previous thermal history, PPO/PA6 containing no more than 6 wt% PPO gave a single melting point (Tm), but the blends with 10–15 wt% PPO exhibited double Tm. Increasing PPO content in PA6 resulted in the transformation of its crystal form from α-crystal to γ-crystal, which might be attributed to hindrance of crystallization of PA6 particles in PPO-rich phase.

Studies on L-valinium Picrate Single Crystal: A Promising NLO Crystal

L-valinium picrate, an organic material, was synthesized and grown by solution growth method. Cell parameters of the grown crystals were obtained from the single crystal X-ray diffraction analysis and the presence of functional groups was identified by FTIR study. The quality of the crystal was also examined by high-resolution X-ray diffraction study. Its optical properties were examined by UV-Vis-NIR analysis, which shows that the crystal is transparent between the wavelengths 400 and 1000 nm. Thermal analysis carried out for the L-valinium picrate exhibits a single sharp melting point at 269 °C. The Vicker’s microhardness values were measured for the grown crystal. Relative powder second harmonic generation efficiency tested by high intensity Nd: YAG laser as a source is about 60 times greater than that of potassium dihydrogen phosphate.

Growth and characterization of pure and doped bis thiourea zinc acetate: Semiorganic nonlinear optical single crystals

Metal–organic coordination complex single crystals bis thiourea zinc acetate (BTZA) and Cd2+ doped BTZA have been synthesized and grown successfully by slow-cooling technique from their aqueous solutions. Single crystals of pure and Cd2+ doped BTZA with dimensions of 35×4×2mm3 and 10×5×6mm3, respectively were obtained with well defined morphology. The as grown single crystals are characterized by single crystal XRD studies and melting point measurements which reveal the incorporation of metallic dopants has not changed the structure of the parent crystal. The powder X-ray diffractogram of the grown crystals has been recorded and the various planes of reflection identified shows shift in the peak positions. The metal coordination with thiourea through sulphur in pure and Cd2+ doped BTZA were ascertained by FTIR studies and optical absorption study to identify the UV cut-off range. The presence of metals in pure and Cd2+ doped BTZA crystal lattice were confirmed by atomic absorption spectroscopy (AAS). The thermal decomposition of pure and Cd2+ doped BTZA crystals were investigated by thermo gravimetric analyses (TGA) and differential thermal analysis (DTA) indicate that doped crystals are more stable than pure crystals. The dielectric response of the crystals were studied in the frequency range 100Hz–5MHz at different temperatures and the results are discussed. Second harmonic generation (SHG) measurement confirms that the pure and Cd2+ doped BTZA have nonlinear optical (NLO) property. Laser damage threshold value of 12.44MW/cm2 has been determined using Q-switched Nd:YAG laser operating at 1064nm and with 8ns pulses in single shot mode for pure BTZA single crystal is reported for the first time.

PCB Association with Model Phospholipid Bilayers

We compare the association of an ortho-substituted and a planar PCB (polychlorinated biphenyls PCB-52 and PCB-77, respectively) with single-component phospholipid bilayers terminated with phosphocholine headgroups. First, fluorescence correlation spectroscopy (FCS) studies of diffusion on supported fluid-phase DLPC show that the ortho-substituted PCB diffuses more slowly, indicating either complex formation or obstructed diffusion. Differential scanning calorimetry (DSC) of vesicles formed from DMPC shows that the gel-to-fluid phase transition temperature is lower for vesicles containing this ortho-substituted PCB. Atomic force microscopy (AFM) shows that, whereas supported bilayers of DMPC containing this ortho-substituted PCB display two melting points, bilayers containing the coplanar PCB display just a single melting point. A model is proposed in which the ortho-substituted PCB resides within the lipid tails of these phospholipid bilayers but the coplanar PCB associates preferentially with the headgroups. This model is consistent with the known membrane disruptive ability of the ortho substituted isomer.