Potential use of ascorbic acid-based surfactants as skin penetration enhancers

6-O-Ascorbic acid alkanoates (ASCn) are amphiphilic molecules having physical-chemical properties that depend on the alkyl chain length. The derivatives of low molecular weight (n < 11) have enough aqueous solubility to produce self-assemblies at room temperature ( approximately 25 degrees C), while those with longer alkyl chains possess a critical micellar temperature (CMT) higher than 30 degrees C. At higher temperatures (T degrees > CMT), ASCn aqueous suspensions turn into either micellar solutions or gel phases, depending on the length of the hydrophobic chain. On cooling, coagels are produced, which possess a lamellar structure that exhibit sharp X-ray diffraction patterns and optical birefringence. The semisolid consistency of such coagels is an interesting property to formulate dermatological pharmaceutical dosage forms able to solubilize and stabilize different drugs. The objective of the present study was the evaluation of the enhancing permeation effect of ASCn with different chain lengths and to correlate permeability changes with histological effects. With this purpose, ASCn coagels containing anthralin (antipsoriasic drug) or fluorescein isothiocyanate (FITC, hydrophobic fluorescent marker) were assayed on rat skin (ex vivo) and mice skin (in vivo), respectively. Also, histological studies were performed aimed at detecting some possible side effects of ASCn. No inflammatory cellular response was observed in the skin when ASCn coagels were applied, suggesting non-irritating properties. Light microscopy indicated slight disruption and fragmentation of stratum corneum. The penetration of ASCn through rat skin epidermis was very fast and quantitatively significant. The permeation of anthralin was significantly increased when the drug was vehiculized in ASCn coagels, compared to other pharmaceutical systems. The results indicated that ASC12 seems to have the highest enhancing effect on FITC permeation. ASC12 appears to be the compound that possesses the highest capacity to enhance the penetration of the drugs. Furthermore, it has the highest permeation of the serie.     

New method for the effective production of ultrafine drug nanocrystals

Particle size reduction, particularly nanonization, is a non-specific, universal approach to improve the bioavailability of poorly soluble drugs. The decreased particle size of drug nanocrystals leads to a distinct increase in surface area. Due to the increased surface area the rate of dissolution will be proportionally raised, leading to a better absorption of the poorly soluble drug. Various technologies for the production of drug nanocrystals are known, e.g., pearl milling (Nanocrystal technology, elan/Nanosystems), high pressure homogenization in water (DissoCubes, SkyePharma) or alternatively in non-aqueous media or water-reduced media (Nanopure, PharmaSol Berlin). A first combinative technology (precipitation followed by high pressure homogenization) is known as NANOEDGETM technology (Baxter). Relatively long milling times, high numbers of homogenization cycles or solvent residues are typical drawbacks of the existing technologies. In order to overcome the limitations of the existing technologies a new combination method was developed for the production of ultra-fine submicron suspensions. The method involves an evaporation step to provide a solvent-free modified starting material followed by high pressure homogenization to produce ultrafine drug nanocrystals. In this study it could be shown that modified hydrocortisone acetate was particularly suitable to be further processed by high pressure homogenization. In comparison to jet-milled hydrocortisone acetate powder the high pressure homogenization of spray-dried hydrocortisone acetate powder resulted in much more homogeneously dispersed nanosuspensions. By using co-processed, spray-dried material (9:1 drug/poloxamer 188 ratio) the required number of homogenization cycles to obtain nanosuspensions was distinctly reduced. In case of the modified material only 1 homogenization cycle at 1500 bar was sufficient to obtain a particle size smaller than that after 20 homogenization cycles using the jet-milled drug powder. The obtained nanosuspensions have shown excellent long-term storage stability.     

Characteristics of fatal motorcycle crashes into roadside safety barriers in Australia and New Zealand

This paper reports on the findings of a retrospective case series study of fatal motorcyclist–roadside barrier collisions. Cases were retrieved from the National Coroners Information System (NCIS), the coronial case files of Australian jurisdictions, and the Crash Analysis System (CAS) of the New Zealand Transport Agency. Seventy seven (77) motorcycle fatalities involving a roadside barrier in Australia and New Zealand were examined. The fatalities usually involved a single vehicle crash and young men. The roadside barriers predominantly involved were steel W-beams, typically on a bend in the horizontal alignment of the road. A majority of fatalities occurred on a weekend, during daylight hours, on clear days with dry road surface conditions indicating predominantly recreational riding. Speeding and driving with a blood alcohol level higher than the legal limit contributed to a significant number of these fatalities.     

数字脉冲脱磁器的应用

磁铁矿经磁选之后给入分级作业及筛分作业之前必须经过脱磁。以消除磁团聚所带来的不利影响。数字脉冲脱磁器是一种新型脱磁器，其脱磁效果好，明显提高分级效率及筛分效率。应用于使用磁性衬板的球磨机与分级机之间，可提高返砂比和磨矿效率。     

Cutting single-walled carbon nanotubes

A two-step process is utilized for cutting single-walled carbon nanotubes (SWNTs). The first step requires the breakage of carbon-carbon bonds in the lattice while the second step is aimed at etching at these damage sites to create short, cut nanotubes. To achieve monodisperse lengths from any cutting strategy requires control of both steps. Room-temperature piranha and ammonium persulfate solutions have shown the ability to exploit the damage sites and etch SWNTs in a controlled manner. Despite the aggressive nature of these oxidizing solutions, the etch rate for SWNTs is relatively slow and almost no new sidewall damage is introduced. Carbon-carbon bond breakage can be introduced through fluorination to ～C(2)F, and subsequent etching using piranha solutions has been shown to be very effective in cutting nanotubes. The final average length of the nanotubes is approximately?100?nm with carbon yields as high as 70-80%.     

Cylindrically etched carbon-fiber microelectrodes for low-noise amperometric recording of cellular secretion

The most important sources of noise with disk-shaped carbon-fiber microelectrodes (CFMEs) are the exposed cut disk face of the fiber itself and the seal region between the carbon fiber and the applied insulating layer. To reduce noise and to fabricate simple, reproducible low-noise CFMEs, we sealed commercially available carbon fibers in pulled glass pipets and then we performed cylindrical etching of the fiber extending beyond the glass sheath, followed by insulation with anodic electrophoretic deposition of paint. The resulting CFMEs had electroactive carbon disks with radii as small as ～0.5 μm. The noise of such electrodes was minimized by virtue of a design that ensures a good seal between the carbon fiber and its insulation and a reduced diameter of the exposed carbon. In contrast to CFMEs made of conically etched carbon fibers, cylindrically etched CFMEs offer the significant advantage that they can be easily reused: The cylindrically etched region extends over several hundreds of micrometers and, therefore, can be cut back repeatedly to expose a fresh carbon surface of uniform diameter. The low noise and small size of these electrodes make them ideal for the high-sensitivity measurements demanded in studies of single-vesicle transmitter release from secretory cells. Furthermore, the small cross-sectional diameter of the tips allows them to be used in restricted spaces, such as inside the tapering micrometer-diameter tips of melted and pulled glass microcapillaries (e.g., patch pipets).     

河南铝土矿选择性磨矿的试验研究

以铝硅比为5～6的河南铝土矿为原料进行了铝土矿的选择性磨矿试验.破碎的产品中Al2O3在粗粒级发生一定程度的富集.球磨机选择性磨矿的试验表明河南铝土矿的选择性磨矿效果较好,可以采用一定的分级工艺直接回收磨矿产品中高铝硅比的粗级别部分,细粒级进入浮选,从而有望实现铝土矿选矿的突破.     

电气石晶体结构中的化学键的计算

对电气石进行XRD及EDS分析测试,并对电气石晶体结构中的化学键进行计算,结果表明:电气石的晶体结构中Mn -O2-键的键长、静电价强度、离子键成分、库仑力、相对键合强度、极性和键价之间具有极好的一致性。     

Trapezius muscle activity as a risk indicator for shoulder and neck pain in female service workers with low biomechanical exposure

Electromyographic activity of the upper trapezius muscles was recorded over the workday for two groups of service workers, shopping centre (n = 22) and healthcare workers (n = 44), both with low observed biomechanical exposure. Static and median EMG activity level, number of EMG gaps and gap time were determined. The variability of these variables over the workday was examined by calculating the coefficient of variation (CV) and the intraclass correlation coefficient (ICC) of 1-h consecutive recording periods. All variables except gap time showed acceptable reliability (ICC = 0.69-0.78), i.e. the largest fraction of variance in the data set was due to intersubject variance, despite relatively large hour-to-hour variation (CV = 0.21 0.62). The EMG activity level in the trapezius muscles was low (static activity level < 1% EMGmax), despite the high prevalence of shoulder and neck pain for both groups of workers. In addition to the work recordings, tests were performed to determine intersubject variation in muscle activity when adopting a standardized resting posture, and in a dynamic muscle activity pattern during paced arm movement. Neither the EMG variables from the work recordings nor the tests with EMG recording indicated higher trapezius EMG activity levels for workers with pain in the shoulders and neck in this study. The low EMG levels are interpreted to indicate a low risk of developing shoulder and neck complaints due to biomechanical exposure for both groups of workers. The possibility of pain-initiating mechanisms, associated with stress and not mediated through muscle activity, is considered in the discussion.     

Surface-relief fiber Bragg gratings for sensing applications

We present a new type of fiber Bragg grating (FBG) in which we etch the grating into the flat surface of a D-shaped optical fiber. Instead of being written in the core of the fiber, as are standard FBGs, these surface-relief FBGs are placed in the cladding above the core. These gratings are a viable alternative to standard FBGs for sensing applications. We describe the fabrication process for etching Bragg gratings into the surface of D-fibers and demonstrate their performance as temperature sensors.