A physical approach to specifically improve the mobility of alkane liquid drops

Seamless control of resistance to liquid drop movement for polar (water) and nonpolar alkane (n-hexadecane, n-dodecane, and n-decane) probe liquids on substrate surfaces was successfully demonstrated using molten linear poly(dimethylsiloxane) (PDMS) brush films with a range of different molecular weights (MWs). The ease of movement of liquid drops critically depended on polymer chain mobility as it relates to both polymer MW and solvent swelling on these chemically- and topographically identical surfaces. Our brush films therefore displayed lower resistances to liquid drop movement with decreasing polymer MW and surface tension of probe liquid as measured by contact angle (CA) hysteresis and tilt angle measurements. Subsequently, while mobility of water drops was inferior and became worse at higher MWs, n-decane drops were found to experience little resistance to movement on these polymer brush films. Calculating CA hysteresis as Δθ(cos) = cos θ(R) - cos θ(A) (θ(A) and θ(R) are the advancing and receding CAs, respectively) rather than the standard Δθ = θ(A) - θ(R) was found to be advantageous for estimation of the actual dynamic dewetting behavior of various probe liquids on an inclined substrate.     

Nanoparticle-based substrates for surface-enhanced Raman scattering detection of bacterial spores

The development of ultrasensitive and rapid methods for the detection of bacterial spores is important for medical diagnostics of infectious diseases. While Surface-Enhanced Raman Spectroscopic (SERS) techniques have been increasingly demonstrated for achieving this goal, a key challenge is the development of sensitive and stable SERS substrates or probes. This Minireview highlights recent progress in exploring metal nanoparticle-based substrates, especially gold nanoparticle-based substrates, for the detection of biomarkers released from bacterial spores. One recent example involves assemblies of gold nanoparticles on a gold substrate for the highly sensitive detection of dipicolinic acid (DPA), a biomarker for bacterial spores such as Bacillus anthracis. This type of substrate exploits a strong SERS effect produced by the particle-particle and particle-substrate plasmonic coupling. It is capable of accurate speciation of the biomarker but also selective detection under various reactive or non-reactive conditions. In the case of detecting Bacillus subtilis spores, the limit of detection is quite comparable (0.1 ppb for DPA, and 1.5 × 10(9) spores per L (or 2.5 × 10(-14) M)) with those obtained using silver nanoparticle-based substrates. Implications of the recent findings for improving the gold nanoparticle-based SERS substrates with ultrahigh sensitivity for the detection of bacterial spores are also discussed.     

相容的聚甲基丙烯酸甲酯/[C12 MIM][PF6]离子液体体系在超临界CO2中的发泡性能

通过快速卸压法, 以超临界CO2为物理发泡剂, 研究了相容的聚甲基丙烯酸甲酯(PMMA)/1-n-十二烷基-3-甲基咪唑六氟磷酸盐([C12 MIM][PF6])离子液体(IL)复合体系的发泡性能. 加入IL后, PMMA对CO2的吸收量增加; 复合体系的玻璃化转变温度(Tg)随IL含量的增加而降低. IL对PMMA发泡行为的影响取决于发泡条件. 在较低温度和压力下, 纯PMMA无法发泡, IL的加入可促进泡孔形成; 提高温度和压力, 纯PMMA可以发泡, IL的加入在提高泡孔尺寸的同时使泡孔仍然保持尺寸分布均匀的微米级结构.     

A molecular dynamics examination of the relationship between self-diffusion and viscosity in liquid metals

The self-diffusion coefficients D and the viscosities η of elemental Ni, Cu, and Ni-Si alloys have been calculated over a wide temperature range by molecular dynamics simulations. For elemental Ni and Cu, Arrhenius-law variations of D and η with temperature dominate. The temperature dependence of Dη can be approximated by a linear relation, whereas the Stokes-Einstein relation is violated. The calculations of D and η are extended to the regions close to the crystallization of Ni(95)Si(5), Ni(90)Si(10), and the glass transitions of Ni(80)Si(20) and Ni(75)Si(25). The results show that both D and η strongly deviate from the Arrhenius law in the vicinity of phase transitions, exhibiting a power-law divergence. We find a decoupling of diffusion and viscous flow just above the crystallization of Ni(95)Si(5) and Ni(90)Si(10). For the two glass-forming alloys, Ni(80)Si(20) and Ni(75)Si(25), the relation Dη = const is obeyed as the glass transition is approached, indicating a dynamic coupling as predicted by the mode-coupling theory. This coupling is enhanced with increasing Si composition and at 25%, Si spans a wide temperature range through the melting point. The decoupling is found to be related to the distribution of local ordered structure in the melts. The power-law governing the growth of solid-like clusters prior to crystallization creates a dynamic heterogeneity responsible for decoupling.     

Cloud-point extraction combined with HPLC for determination of larotaxel in rat plasma: a pharmacokinetic study of liposome formulation

A simple and efficient method based on cloud-point extraction combined with high-performance liquid chromatography was developed and validated for the determination of larotaxel in rat plasma. Nonionic surfactant Triton X-114 was chosen as the extraction solvent. Variable parameters affecting the cloud-point extraction efficiency, for example the nature and concentration of surfactant, NaOH concentration, incubation temperature, and time were evaluated and optimized. Chromatographic separation was accomplished on a Diamonsil C(18) column (150 mm × 4.6 mm, 5 μm) using a mobile phase consisting of acetonitrile and 0.1% phosphoric acid with pH 4.0 (60:40, v/v). The calibration curve showed good linearity over the range of 0.05-10 μg/mL. Under the optimum conditions, the method was shown to be reproducible and reliable with intraday precision below 5.7%, interday precision below 7.2%, accuracy within ±3.5%, and mean extraction recovery of 91.8-94.2%. The validated method was successfully applied to the pharmacokinetic study of larotaxel in rat plasma after a single intravenous administration of larotaxel injection and larotaxel-loaded liposome, respectively. The results indicated that the larotaxel-loaded liposome led to significant differences in pharmacokinetic profile.     

Microfluidic electronics

Microfluidics, a field that has been well-established for several decades, has seen extensive applications in the areas of biology, chemistry, and medicine. However, it might be very hard to imagine how such soft microfluidic devices would be used in other areas, such as electronics, in which stiff, solid metals, insulators, and semiconductors have previously dominated. Very recently, things have radically changed. Taking advantage of native properties of microfluidics, advances in microfluidics-based electronics have shown great potential in numerous new appealing applications, e.g. bio-inspired devices, body-worn healthcare and medical sensing systems, and ergonomic units, in which conventional rigid, bulky electronics are facing insurmountable obstacles to fulfil the demand on comfortable user experience. Not only would the birth of microfluidic electronics contribute to both the microfluidics and electronics fields, but it may also shape the future of our daily life. Nevertheless, microfluidic electronics are still at a very early stage, and significant efforts in research and development are needed to advance this emerging field. The intention of this article is to review recent research outcomes in the field of microfluidic electronics, and address current technical challenges and issues. The outlook of future development in microfluidic electronic devices and systems, as well as new fabrication techniques, is also discussed. Moreover, the authors would like to inspire both the microfluidics and electronics communities to further exploit this newly-established field.     

Can curcumin food and <Emphasis Type="Italic">Bacillus subtilis</Emphasis> drug be taken simultaneously?

Curcumin (CUR), a frequently-used food additive and flavorings, has been reported to be safe at a wide dose range. Bacillus subtilis (B. subtilis) is commonly found in soil and decomposing organic matter, and it was reported beneficial for humans when ingested. Up to now, there have been no contraindication of B. subtilis except for the avoidance of the drug combination with antibiotics, and the interaction of food and B. subtilis drug is blank. In this study, the interaction of CUR and B. subtilis was investigated. Microcalorimetry was applied to evaluate the effect of CUR on B. subtilis growth. By analyzing the main parameters extracted from the heat-flow power–time curves, it was concluded that CUR could inhibit the growth of B. subtilis, and the 50% inhibiting concentration (IC₅₀) valued 109.9 μg mL⁻¹. The results revealed that it is unreasonable to take CUR and B. subtilis at the same time, and it also provided a new way for the investigation of the interaction between food and drug. Meanwhile, this study indicated that the safety of CUR should be re-evaluated.     

Electrocatalytic dechlorination of chloroacetic acids by silver nanoparticles modified glassy carbon electrode

A simple potentiostatic method was employed to prepare silver nanoparticles deposited on glassy carbon electrode. The silver nanoparticles exhibit extraordinary electrocatalytic activities toward the reduction process of chloroacetic acids. The electrochemical behavior of trichloroacetic acid, dichloroacetic acid, and monochloroacetic acid has been investigated by cyclic voltammetry at the silver nanoparticles-modified glassy carbon electrode in 0.1 M LiClO₄ solution; each compound exhibits a series of reduction peaks which represent sequential dechlorination steps up to acetic acid. The electrocatalytic dechlorination mechanism for chloroacetic acids was also discussed in this work.     

还原温度对Fe-Mo催化剂性质及F-T合成性能的影响

研究了还原温度对Fe-Mo催化剂性质及费托(F-T)合成性能的影响。采用N₂物理吸附、X射线衍射、穆斯堡尔谱和H₂程序升温脱附技术对催化剂进行了表征。结果表明,随还原温度升高,金属铁晶粒粒径增大,金属铁上的H₂吸附量先升后降;催化剂还原度提高,反应态催化剂碳化铁含量递增。催化剂F-T合成性能在280 ℃、1.5 MPa、2 000 h^-1、合成气H₂/CO比为2.0条件下在固定床反应器中测试。反应结果表明,随还原温度提高,催化剂接近稳态时的活性和重质烃选择性(C₅⁺)先升后降,而甲烷选择性则先降后升。350 ℃还原催化剂具有最佳F-T合成反应性能。