Experimental Investigation On Hydrate Dissociation in Near-Wellbore Region Caused By Invasion of Drilling Fluid: Ultrasonic Measurement and Analysis

As we all know, development and utilization of clean energy is the only way for society to achieve sustainable development. Although natural gas hydrates is a new type of clean energy, uncontrollable hydrate dissociation and accompanying methane leakage in drilling operation threaten drilling safety and marine environment. However, dissociation range of natural gas hydrates around wellbore can't be reasonably and clearly determined in previous investigations, which may lead to the inaccurate estimation of borehole collapse and methane leakage. Then, the marine environment will be greatly damaged or affected. The purpose of the present work is to experimentally explore the dissociation characteristics of natural gas hydrates around wellbore in drilling operation, and analyze the influence law and mechanism of various factors on hydrate dissociation. It is expected to provide reference for exploring effective engineering measures to avoid the uncontrolled hydrate dissociation, borehole collapse and accompanying methane leakage. The experimental results demonstrate that acoustic velocity of hydrate-bearing sediment can be accurately expressed as quadratic polynomial of hydrate saturation, which is the theoretical basis for determination of hydrate saturation in subsequent experiments. Owing to the fact that hydrate dissociation is an endothermic reaction, hydrate dissociation gradually slows down in experiment. Throughout the experiment, the maximum dissociation rate at the beginning of the experiment is 8.69 times that at the end of the experiment. In addition, sensitivity analysis found that the increase of stabilizer concentration in drilling fluid can inhibit hydrate dissociation more than the increase in hydrate saturation. Hydrate dissociation was completely inhibited when the concentration of soybean lecithin exceeds 0.60wt%, but hydrate dissociation definitely occurs in the near-wellbore region no matter what hydrate saturation is. In this way, based on the requirements of drilling safety and environment protection, hydrate dissociation and accompanying methane leakage can be controlled by designing and adjusting the stabilizer concentration in drilling fluid.

Measuring the Anisotropy in Interfacial Tension of Nematic Liquid Crystals

Liquid crystal (LC) phases typically show anisotropic alignment-dependent properties, such as viscosity and dielectric permittivity, so it stands to reason that LCs also have anisotropic interfacial tensions. Measuring the interfacial tension γ of an LC with conventional methods, such as pendant drops, can be challenging, however, especially when we need to know γ for different LC aligning conditions, as is the case when we seek Δγ, the interfacial tension anisotropy. Here, we present measurements of Δγ of the common synthetic nematic LC compound 5CB against water using a microfluidic droplet aspiration technique. To ensure tangential and normal alignment, respectively, we add poly(vinyl alcohol) (PVA) and sodium dodecylsulfate (SDS), respectively, as a stabilizer and measure γ for different concentrations of stabilizer. By fitting the Szyszkowski equation to the data, we can extrapolate to zero-stabilizer concentration, obtaining the γ of 5CB to pure water for each alignment. For normal alignment, we find γ⊥=31.9±0.8 mN·m−1, on the order of 1 mN·m−1 greater than γ||=30.8±5 mN·m−1 for tangential alignment. This resonates with the empirical knowledge that 5CB aligns tangentially to an interface with pure water. The main uncertainty arises from the use of polymeric PVA as tangential-promoting stabilizer. Future improvements in accuracy may be expected if PVA can be replaced by a low molar mass stabilizer that ensures tangential alignment.

First principles computation of composition dependent elastic constants of omega in titanium alloys: implications on mechanical behavior

For decades the poor mechanical properties of Ti alloys were attributed to the intrinsic brittleness of the hexagonal ω-phase that has fewer than 5-independent slip systems. We contradict this conventional wisdom by coupling first-principles and cluster expansion calculations with experiments. We show that the elastic properties of the ω-phase can be systematically varied as a function of its composition to enhance both the ductility and strength of the Ti-alloy. Studies with five prototypical β-stabilizer solutes (Nb, Ta, V, Mo, and W) show that increasing β-stabilizer concentration destabilizes the ω-phase, in agreement with experiments. The Young’s modulus of ω-phase also decreased at larger concentration of β-stabilizers. Within the region of ω-phase stability, addition of Nb, Ta, and V (Group-V elements) decreased Young’s modulus more steeply compared to Mo and W (Group-VI elements) additions. The higher values of Young’s modulus of Ti–W and Ti–Mo binaries is related to the stronger stabilization of ω-phase due to the higher number of valence electrons. Density of states (DOS) calculations also revealed a stronger covalent bonding in the ω-phase compared to a metallic bonding in β-phase, and indicate that alloying is a promising route to enhance the ω-phase’s ductility. Overall, the mechanical properties of ω-phase predicted by our calculations agree well with the available experiments. Importantly, our study reveals that ω precipitates are not intrinsically embrittling and detrimental, and that we can create Ti-alloys with both good ductility and strength by tailoring ω precipitates' composition instead of completely eliminating them.

Preparation of Magnesia Partially Stabilized Zirconia Nanomaterials from Zirconium Hydroxide and Magnesium Carbonate Precursors Using PEG as a Template

Stabilized zirconia is a promising material due to its great physical and chemical properties, and thermal stability. In this work, MgO was used as a stabilizer in ZrO2 to obtain Magnesia Partially Stabilized Zirconia (MSZ) nanomaterials assisted with PEG as a template through conventional mixing process. Zirconium hydroxides prepared from local zircon and MgCO3 were used as MSZ precursors. Meanwhile, the stabilizer concentration was varied from 1 to 4 wt% of ZrO2. The effect of the stabilizer concentration and the calcination temperature to the crystallinity and the morphological properties of the MSZ nanoparticles were studied using X-ray diffraction and scanning and transmission electron microscopy. The ZrO2 content in the zirconium hydroxides precursors is accounting 89.52 wt% of the total and exhibits the dominant m-phase at 1000 °C. Meanwhile, the tetragonal and the monoclinic phases were formed in all MSZ samples at a temperature of 800–1000 °C. The as-synthesized MSZ samples show typical FT-IR spectra, consisting of the metal–oxygen bonds at below 500 cm−1 and the organic functional groups ranging at 1000–3000 cm−1. The ZrO2 morphologies exhibit spherical-like shapes with elongated agglomeration at 800 °C. In addition, the average particle sizes of the final product ranges from 20 to 50 nm. At a sintering temperature of 1500 °C, MSZ samples show the monoclinic phase of ZrO2 and densities in the range of 3.95–4.14 g/cm3.

Surface Engineering of Fenofibrate Nanocrystals Using Nano-by-Design Multivariate Integration: A Biopharmaceutical and Pharmacokinetic Perspective

Introduction: Surface engineering of nanocrystals for improving the biopharmaceutical features is a multivariate process involving numerous formulation and process variables, thus making it a complicated process to get the desired biopharmaceutical quality profile. Nano-by-design is hereby proposed as an approach to nanonize an orally active, lipid lowering fenofibrate, to improve feasibility in product development. Methodology: Top-down wet ball milling (media milling) in zirconia planetary chamber was methodically explored for improving the solubility and bioavailability of fenofibrate by formulating a nanosuspension using polyvinyl alcohol as a stabilizer. Several influencing variables were screened using a systematic one-factor-at-a-time approach. DSC, SEM, XRD, and FTIR were utilized for physical characterization of the product during the development stage and study the effect of milling time, milling speed, fenofibrate: stabilizer ratio, premilling time and stabilizer concentration. Potential risk factors affecting critical quality biopharmaceutical attributes of fenofibrate nanocrystals like size, zeta potential, in vitro release, crystallinity and intrinsic solubility were optimized to improve pharmacokinetic performance. Result: Formulated nanosized fenofibrate exhibited a crystalize nature as evident from XRD and DSC, 411 nm size, and a rapid but complete dissolution (~99% in 30 min). This resulted into quick onset of action and improved bioavailability as observed from 51.46% shorter Tmax, 82.63% higher Cmax, and 69.34% higher AUC0–24h, respectively.

To Study the Significance of Processing Variables Using Quality by Design for Optimization of Nanoparticulate System of Cilnidipine

This investigation aimed to prepare Cilnidipine Nanoparticles by nanoprecipitation ultrasonication method and to study the significance of processing variables by applying quality by design. Cilnidipine is fourth-generation dual L/N-type Ca2+ channel blocker used for the management of hypertension. It is BCS class-II drug exhibiting lower aqueous solubility, which tends to lower bioavailability. The combination of Poloxamer 188 and Tween 80 was used as a stabilizer. The design of the experiment is one of the tools of Quality by design. Plackett-Burman design was applied for the screening of processing variables, which are significant for the method. The processing variables screened were stirring speed, antisolvent ratio, drug concentration, polymer concentration, stabilizer concentration. The effect of each parameter evaluated by particle size, entrapment efficiency, and drug release at 10 minutes of prepared Nanoparticles of Cilnidipine. Analysis of variance and Pareto-plot of Plackett-Burman design were utilized to find the significance of the factor and extent of the effect. The surface morphology of Cilnidipine Nanoparticles was studied by SEM. The Pareto plot, as well as statistical analysis of design, had shown that the Concentration of drug, solvent: antisolvent ratio and concentration of poloxamer 188 were the significant parameters for the method. The stabilizer concentration, the stirring speed, and the antisolvent ratio had a negative effect of while the concentration of drug has a positive effect on the particle size of Nanoparticles and drug release at 10 minutes and positive effect of entrapment efficiency of Cilnidipine Nanoparticles. The Cilnidipine Nanoparticles were characterized by FTIR and DSC analysis.

Gastric Ulcer Prevention by Lansoprazole

The objective of the current investigation is to formulate ethyl cellulose and hydroxypropyle methyle cellulose based sustained release microspheres, containing lansoprazole as model drugs. lansoprazole is type II anti-ulcer agent when administered shows synergetic effect in their action. Microspheres were prepared by W/O/O double emulsion solvent evaporation method with different stabilizer concentration and at different speeds of emulsification while maintaining constant amount of lansoprazole. Drug excipient compatibility study was performed prior to formulation development and only compatible excipients were used in the fabrication of microspheres. Prepared microsphere formulations were characterized by percentage yield, particle size analysis, entrapment efficiency, invitro release behavior, differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). SEM studies showed that the microspheres were spherical with rough surface morphology. The drug loaded microspheres showed 10.4-57.9% entrapment capacity for lansoprazole and The invitro release profile showed a slow and steady release pattern for lansoprazole. A 95-98% was releases within a period of 12 hrs . The drug release was found to be diffusion controlled mechanism. The n value of Korsmeyer Peppas equation indicated non Fickian type of diffusion.