Hydrogen embrittlement behavior of high strength low carbon medium manganese steel under different heat treatments

Hydrogen embrittlement (HE) behavior was investigated in a low carbon medium Mn steel with three different volume fraction of retained austenite (RA), which was obtained after different heat treatments. The hydrogen permeation test showed a higher permeability for directly water quenched specimen compared to quench-tempered specimens. Melt extraction test showed hydrogen concentration increased with hydrogen charging current density in the order of directly quenched specimen, QLA, quenched with low-temperature annealed specimens and QHA quenched with high-temperature annealed specimens. Slow strain-rate tensile test was employed to examine the HE behavior, the HE indices decreased with the increase of RA irrespective of increased hydrogen concentration. HE susceptibility can be suppressed by raising intercritical annealing temperature because Mn enrichment increases the stability of RA.     

Water-stable ZIF-300/Ultrason(R) mixed-matrix membranes for selective CO2 capture from humid post combustion flue gas

Water stable mixed-matrix membranes (MMMs) were developed to help control the global warming by capturing and sequestrating carbon dioxide (CO2) from post-combustion flue gas originated from burning of fossil fuels.MMMs of different compositions were prepared by doping glassy polymer Ultrason(R) S 6010 (US) with nanocrystals of zeolitic imidazolate frameworks (ZIF-300) in varying degrees.Solution-casting technique was used to fabricate various MMMs to optimize their CO2 capturing performance from both dry and wet gases.The prepared composite membranes indicated enhanced filler-polymer interfacial adhesion,consistent distribution of nanofiller,and thermally established matrix configuration.CO2 permeability of the membranes was enhanced as demonstrated by gas sorption and permeation experiments performed under both dry and wet conditions.As compared to neat Ultrason(R) membrane,CO2 permeability of the composite membrane doped with 40 wt％ ZIF-300 nanocrystals was increased by four times without disturbing CO2/N2 ideal selectivity.In contrast to majority of previously reported membranes,key features of the fabricated MMMs include their structural stability under humid conditions coupled with better and unaffected gas separation performance.     

A comparative study of the friction and wear behavior of untreated mild steel and its boron-permeated counterpart under lubrication of liquid paraffin containing zinc dialkyldithio-phosphate

AISI-1045 steel was treated with solid boron permeation, and the interaction between the modified surface layer and the lubricating additive zinc dialkyldithio-phosphate (ZDDP) was examined. The friction and wear behavior of the treated and untreated steel specimens were compared. The phase composition of the boron-permeated layer was examined by means of X-ray diffraction. The chemical states of several typical elements on the worn surfaces of the treated and untreated steel surfaces were examined by means of Auger electron spectroscopy and X-ray photoelectron spectroscopy. Results showed that the wear-resistance of boron-permeated specimens was higher than that of the untreated ones. This was partly attributed to the change in the hardness and phase composition of the steel surfaces after boron permeation. Tribochemical reactions between steel and the active elements of the additive occurred during the sliding of the treated and untreated steel discs against an AISI-52100 steel ball using different lubricants. The resultant surface protective films containing various tribochemical products, together with the adsorbed boundary lubricating film, contributed to the reduction of friction and wear.     

Transport Properties of the Mixed-Conducting SrFe1.2Co0.3Ox

Single phase SrFe_1.2Co_0.3O_x sample with layered crystal structure was prepared using a solid state reaction method. Electrical conductivity and apparent oxygen diffusion coefficients of the SrFe_1.2Co_0.3O_x sample were measured as functions of temperature in atmospheres of various oxygen partial pressures . Total and ionic conductivities were determined by using the conventional four-probe and electron blocking four-probe methods, respectively. The apparent oxygen diffusion coefficient was derived from the time-dependent conductivity relaxation data of the reequilibrium process after abruptly changing the in the surrounding atmosphere. Several atmospheres of different were established by the use of premixed gas cylinders. The conductivity of SrFe_1.2Co_0.3O_x increases with increasing temperature and . At 900°C in air, the total conductivity and ionic conductivity are 10 and 8S · cm^-2, respectively. The ionic transference number ( 0.8 in air) does not have strong temperature dependence. The activation energy increases with decreasing . In air, the activation energy has a low value of 0.37 eV. The apparent oxygen diffusion coefficient was at 950°C over a wide range of .     

Evaluation of automobile service performance using laboratory testing

A methodology is presented to evaluate martensitic advanced high-strength steels in auto service. There was essentially no influence of hydrogen for (i) linearly increasing stress tests of specimens with hydrogen contents much greater than for automobile service, and (ii) for tensile tests with simultaneous hydrogen charging and with a substantial hydrogen content. These results allow evaluation of the hydrogen influence for the tested steels for auto service. In contrast, electrochemically hydrogen charged martensitic advanced high-strength steels showed an influence of hydrogen on mechanical properties, manifest as (i) a decrease in yield strength, by hydrogen enhanced macroscopic ductility, and (ii) a change of the micro-fracture mode, by hydrogen-assisted micro-fracture.     

Topical delivery of tetrahydrocurcumin lipid nanoparticles effectively inhibits skin inflammation: in vitro and in vivo study

Tetrahydrocurcumin (THC) also referred to as ‘white curcumin’, is a stable colorless hydrogenated product of curcumin with superior antioxidant and anti-inflammatory properties. The present study is an attempt to elevate the topical bioavailability of THC, post-incorporation into a nano-carrier system with its final dosage as a hydrogel. Lipid nanoparticles of THC (THC-SLNs) prepared by microemulsification technique were ellipsoidal in shape (revealed in transmission electron microscopy) with a mean particle size of 96.6?nm and zeta potential of ?22?mV. Total drug content and entrapment efficiency of THC-SLNs was 94.51%?±?2.15% and 69.56%?±?1.35%, respectively. Differential scanning calorimetry and X-ray diffraction studies confirmed the formation of THC-SLNs. In vitro drug release studies showed the drug release from THC-SLNs gel to follow Higuchi’s equation revealing a Fickian diffusion. Ex vivo permeation studies indicated a 17 times (approximately) higher skin permeation of THC-SLNs gel as compared with the free THC gel. Skin irritation, occlusion, and stability studies indicated the formulation to be nonirritating, and stable with a desired occlusivity. Pharmacodynamic evaluation in an excision wound mice model clearly revealed the enhanced anti-inflammatory activity of THC-SLNs gel and was further confirmed using biochemical and histopathological studies. It is noteworthy to report here that THC-SLNs gel showed significantly better (p?≤?0.001) activity than free THC in gel. As inflammation is innate to all the skin disorders, the developed product opens up new therapeutic avenues for several skin diseases. To the best of our knowledge, this is the first paper elaborating the therapeutic usefulness of white curcumin-loaded lipidic nanoparticles for skin inflammation.     

Impact of various solid carriers and spray drying on pre/post compression properties of solid SNEDDS loaded with glimepiride: in vitro-ex vivo evaluation and cytotoxicity assessment

Development of self-nanoemulsifying drug delivery systems (SNEDDS) of glimepiride is reported with the aim to achieve its oral delivery. Lauroglycol FCC, Tween-80, and ethanol were used as oil, surfactant, and co-surfactant, respectively as independent variables. The optimized composition of SNEDDS formulation (F1) was 10% v/v Lauroglycol FCC, 45% v/v Tween 80, 45% v/v ethanol, and 0.005% w/v glimepiride. Further, the optimized liquid SNEDDS were solidified through spray drying using various hydrophilic and hydrophobic carriers. Among the various carriers, Aerosil 200 was found to provide desirable flow, compression, dissolution, and diffusion. Both, liquid and solid-SNEDDS have shown release of more than 90% within 10?min. Results of permeation studies performed on Caco-2 cell showed that optimized SNEDDS exhibited 1.54 times higher drug permeation amount and 0.57 times lower drug excretion amount than that of market tablets at 4?hours (p?p?>?.05, i.e. 0.74). The formulation was found stable with temperature variation and freeze thaw cycles in terms of droplet size, zeta potential, drug precipitation and phase separation. Crystalline glimepiride was observed in amorphous state in solid SNEDDS when characterized through DSC, PXRD, and FT-IR studies. The study revealed successful formulation of SNEDDS for glimepiride.     

一种亲水反应型聚氨酯在高寒草原生态修复中的应用研究

高寒草原退化以及沙化现象对当地的生态系统造成严重破坏。在多种生态修复措施中,以材料措施为技术核心的生态修复措施受到广泛关注。本工作选用一种亲水反应型聚氨酯(OH-1A)作为主要材料,对其进行相关性能研究。结果表明:在15 ℃条件下,OH-1A可分散于水中,发生固化反应形成弹性凝胶体,且固化速率与浓度成正比;当OH-1A浓度达到3%时,可在300 s内渗透50 mm,并发生固化反应,形成柔性固结层;固结层表面静态接触角可达143°,优异的表面疏水性能有助于减缓植物生长所需水分的蒸发。在沙化严重的高寒草原,以OH-1A为基础的材料措施,可为植物的生根发芽提供有利的保障环境,防止草种或幼苗受到恶劣环境的影响,即建设“植物栖息”环境。因此,本工作提出的材料措施生态修复技术在高寒草原的植被恢复研究和应用中具有较高的潜在价值。     

Effect of cathodic hydrogen-charging current density on the hydrogen diffusivity in nanostructured bainitic steels

ABSTRACT

The effect of cathodic hydrogen-charging current on the effective hydrogen diffusivity in nanostructured bainitic steels produced at transformation temperatures 200°C (BS200) and 350°C (BS350) was investigated and compared to that of mild steel. The effective hydrogen diffusivity at 10?mA?cm^?2 was the lowest for BS200, followed by BS350 and mild steel, due to the finer microstructure and higher dislocation density in the bainitic ferrite of BS200. Increase in the hydrogen-charging current density, i.e. 20 and 30?mA?cm^?2, increased the effective hydrogen diffusivity of mild steel by 37 and 135%, and BS350 by 49 and 150%, respectively. For BS200, the increase was not significant (2%) at 20?mA?cm^?2, but increased by 34% at 30?mA?cm^?2.

This paper is part of a thematic issue on Hydrogen in Metallic Alloys     

Development of a Soluplus budesonide freeze-dried powder for nasal drug delivery

Objective: The aim of this work was to develop an amorphous solid dispersions/solutions (ASD) of a poorly soluble drug, budesonide (BUD) with a novel polymer Soluplus^® (BASF, Germany) using a freeze-drying technique, in order to improve dissolution and absorption through the nasal route.

Significance: The small volume of fluid present in the nasal cavity limits the absorption of a poorly soluble drug. Budesonide is a corticosteroid, practically insoluble and normally administered as a suspension-based nasal spray.

Methods: The formulation was prepared through freeze-drying of polymer-drug solution. The formulation was assessed for its physicochemical (specific surface area, calorimetric analysis and X-ray powder diffraction), release properties and aerodynamic properties as well as transport in vitro using RPMI 2650 nasal cells, in order to elucidate the efficacy of the Soluplus–BUD formulation.

Results: The freeze-dried Soluplus–BUD formulation (LYO) showed a porous structure with a specific surface area of 1.4334?±?0.0178 m²/g. The calorimetric analysis confirmed an interaction between BUD and Soluplus and X-ray powder diffraction the amorphous status of the drug. The freeze-dried formulation (LYO) showed faster release compared to both water-based suspension and dry powder commercial products. Furthermore, a LYO formulation, bulked with calcium carbonate (LYO-Ca), showed suitable aerodynamic characteristics for nasal drug delivery. The permeation across RPMI 2650 nasal cell model was higher compared to a commercial water-based BUD suspension.

Conclusions: Soluplus has been shown to be a promising polymer for the formulation of BUD amorphous solid suspension/solution. This opens up opportunities to develop new formulations of poorly soluble drug for nasal delivery.