A serpentine laminating micromixer combining splitting/recombination and advection

Mixing enhancement has drawn great attention from designers of micromixers, since the flow in a microchannel is usually characterized by a low Reynolds number (Re) which makes the mixing quite a difficult task to accomplish. In this paper, a novel integrated efficient micromixer named serpentine laminating micromixer (SLM) has been designed, simulated, fabricated and fully characterized. In the SLM, a high level of efficient mixing can be achieved by combining two general chaotic mixing mechanisms: splitting/recombination and chaotic advection. The splitting and recombination (in other terms, lamination) mechanism is obtained by the successive arrangement of "F"-shape mixing units in two layers. The advection is induced by the overall three-dimensional serpentine path of the microchannel. The SLM was realized by SU-8 photolithography, nickel electroplating, injection molding and thermal bonding. Mixing performance of the SLM was fully characterized numerically and experimentally. The numerical mixing simulations show that the advection acts favorably to realize the ideal vertical lamination of fluid flow. The mixing experiments based on an average mixing color intensity change of phenolphthalein show a high level of mixing performance was obtained with the SLM. Numerical and experimental results confirm that efficient mixing is successfully achieved from the SLM over the wide range of Re. Due to the simple and mass producible geometry of the efficient micromixer, SLM proposed in this study, the SLM can be easily applied to integrated microfluidic systems, such as micro-total-analysis-systems or lab-on-a-chip systems.     

Non-quadratic-intensity dependence of two-photon absorption induced fluorescence of organic chromophores in solution

We have provided a model to interpret the non-quadratic-intensity dependence behavior commonly observed in the two-photon fluorescence (TPF) experiment excited with high laser intensity. The model also provides one with a different technique to measure the two-photon absorption cross section of an organic chromophore in solution. In contrast to the commonly used low intensity technique that depends on the quadratic-intensity law, the present technique is based on the non-quadratic-intensity dependence of two-photon fluorescence. Auxiliary data such as two-photon quantum efficiency and fluorescence collection efficiency, essential in the low intensity method, are not required in the present technique. TPF measurements of Rhodamine B in methanol are carried out to demonstrate the validity of the present method. The method is used to determine the two-photon absorption cross section of a new chromophore attached with tricyano-derivatized furan as the electron acceptor. The two-photon absorption cross section measured using this method is also compared with that using a conventional transmission technique.     

Two new standard reference materials for the determination of drugs of abuse in human hair

Two new standard reference materials (SRM) for drugs of abuse in human hair have been developed. SRM 2379 consists of hair spiked with cocaine, benzoylecgonine, cocaethylene, phencyclidine, amphetamine, and methamphetamine. SRM 2380 consists of hair spiked with codeine, morphine, monoacetylmorphine, and tetrahydrocannabinol (THC). The SRMs were prepared by soaking the hair in a solution of the target analytes in water-dimethylsulfoxide. The concentration of each analyte was determined using two methods, one based upon gas chromatography/mass spectrometry (GC/MS) and one based upon liquid chromatography/mass spectrometry (LC/MS). Both methods used 0.1 M HCl for extraction of all the analytes from the hair, except for THC, which was extracted with 1 M NaOH. For isolation of the analytes from the extracts, the GC/MS-based methods used different clean-up procedures from those used for the LC/MS-based methods. The results from the two methods were in good agreement with mean differences for the analytes ranging from 4% to 16%. These materials will enable laboratories performing analyses of hair for drugs of abuse to test the accuracy of their methods.     

Electron spin resonance studies of the radiolysis of bi-π-cyclopentadienylalkyls of molybdenum and tungsten

Exposure of (C₅H₅)₂MO(CH₃)₂ and (C₅H₅)₂W(CH₃)₂, prepared from the corresponding dichlorides, to ²⁰Co γ-rays at 77 K gave H₂C.CML₃ carbene species characterised by their ESR spectra, together with a central feature possibly due to the parent cations. Dilute solutions in CD₃OD gave features assigned to the parent anions which were converted on bleaching with visible light into methyl radicals, and H₂C.ML₃ radicals. From the magnitude of the ¹H and ¹⁸³W hyperfine coupling constants, it is deduced that the SOMO for H₂C.WL₃ radicals is strongly localised on carbon.Dilute solutions in aqueous sulphuric acid also gave species with A(2H) = 20 G, identified as the carbene derivatives, H₂C.Ml₃. These were formed on annealing, as signals assigned to HSO₄ · radicals were lost.     

α-CGRP disrupts amylin fibrillization and regulates insulin secretion: implications on diabetes and migraine

Despite being relatively benign and not an indicative signature of toxicity, fibril formation and fibrillar structures continue to be key factors in assessing the structure–function relationship in protein aggregation diseases. The inability to capture molecular cross-talk among key players at the tissue level before fibril formation greatly accounts for the missing link toward the development of an efficacious therapeutic intervention for Type II diabetes mellitus (T2DM). We show that human α-calcitonin gene-related peptide (α-CGRP) remodeled amylin fibrillization. Furthermore, while CGRP and/or amylin monomers reduce the secretion of both mouse Ins1 and Ins2 proteins, CGRP oligomers have a reverse effect on Ins1. Genetically reduced Ins2, the orthologous version of human insulin, has been shown to enhance insulin sensitivity and extend the life-span in old female mice. Beyond the mechanistic insights, our data suggest that CGRP regulates insulin secretion and lowers the risk of T2DM. Our result rationalizes how migraine might be protective against T2DM. We envision the new paradigm of CGRP : amylin interactions as a pivotal aspect for T2DM diagnostics and therapeutics. Maintaining a low level of amylin while increasing the level of CGRP could become a viable approach toward T2DM prevention and treatment.

CGRP concentration is elevated in migraine conditions. The protective effect of migraine against type 2 diabetes is attributed to the ability of CGRP to remodel human amylin aggregation and to suppress the secretion of mouse insulin 2 (the orthologue of human insulin).     

Conjugated enynes as a new type of substrates for olefin metathesis

[reaction: see text] It has been demonstrated for the first time that conjugated enynes can be employed as a facile substrate in olefin metathesis with the use of a bispyridine-substituted ruthenium benzylidene catalyst. Cross-metathesis of the enynes with alkenes turns out to proceed with preferential formation of (Z)-isomers over (E)-isomers up to >25:1 in moderate to good yields. The intramolecular version of conjugated enynes affords novel butadienyl cycloalkenes, which are a highly useful synthetic building blocks, in acceptable yields.     

Mono- and Dinuclear d(10) Metal Complexes of Hexakis(3,5-dimethylpyrazolyl)cyclotriphosphazene. Synthesis, Structures, and Unusual Solution Dynamic Behavior

Synthesis, structures, and unusual solution dynamic processes of d(10) metal complexes of hexakis(3,5-dimethylpyrazolyl)cyclotriphosphazene (L) are reported. Reaction systems with three MX(n):L mole ratios (MX(n) = d(10) metal halide) in CH(2)Cl(2) have resulted in the formation of [ICu(&mgr;,eta(3),eta(3)-L)CuI] (1), [Cl(2)Zn(&mgr;,eta(2),eta(3)-L)ZnCl(2)] (2), [Cl(2)Cd(&mgr;,eta(3),eta(3)-L)CdCl(2)] (3), and [(eta(3)-L)HgCl(2)] (4). These compounds were characterized by single crystal X-ray diffraction studies, and crystallographic data are given in the order of compound: crystal system; space group; unit cell parameters; Z; unique data (I > 2sigma(I)); R(1). 1.0.5CH(2)Cl(2): monoclinic; P2(1)/c; a = 8.268(4) ?; b = 22.365(5) ?; c = 23.325(8) ?, beta = 93.06(1) degrees; 4; 5736; 4.82. 2.CH(3)CN: monoclinic; P2(1)/c; a = 17.021(3) ?; b = 12.161(2) ?; c = 23.608(5) ?; beta = 107.72(1) degrees; 4; 5469; 3.16. 3.CH(2)Cl(2): monoclinic; P2(1)/n; a = 18.585(5) ?; b = 17.585(4) ?; c = 14.404(3) ?; beta = 102.71(2) degrees; 4; 3814; 3.65. The structure of 4 was attempted but resulted in data of low precision. Reaction of L with CuI and ZnCl(2) in an equimolar ratio afforded [ICu(&mgr;,eta(3),eta(3)-L)ZnCl(2)] (5) which crystallizes in monoclinic space group P2(1)/n with a = 22.876(5) ?, b = 21.594(4) ?, c = 9.177(2) ?, beta = 93.54(2) degrees, Z = 4, and R(1) = 7.00 for 3806 (I > 2sigma(I)) data. In all cases, metal halide centers except the Td zinc site in 2 are coordinated by L via a kappa(3)N binding core consisting of two nongeminal pyrazolyl nitrogen atoms and one phosphazene ring nitrogen atom. The eta(2)-N(2) coordination in 2 involves two geminal pyrazolyl nitrogen atoms. Factors which govern the nuclearity of the complex were partially demonstrated. The intermetallic distances in dinuclear metallophosphazenes range from 6.790 to 7.195 ?. The solution behavior of five compounds was studied by variable temperature (31)P{(1)H}, (1)H, and (113)Cd FT NMR spectroscopy. Compounds 1 and 4 are associated with fluxional motions involving A(2)B low-temperature limit spectrum while compounds 2 and 5 show solvent-dependent dynamic processes with ABX and A(2)B low-temperature limit spectral patterns. Compounds 3 constitutes a fluxional system involving three A(2)B species. Accounts of solution NMR spectra were attempted by using PANIC, by assuming the formation of new solution metallophosphazene species and by considering several types of dynamic processes such as a ring-around type hopping motion for the kappa(3)N metal site, a Td conformational change for the geminal pyrazolyl kappa(2)N metal site, and a wigwag motion for the nongeminal pyrazolyl kappa(2)N metal unit.     

Dysfunction of Shh signaling activates autophagy to inhibit trophoblast motility in recurrent miscarriage

In early pregnancy, the placenta anchors the conceptus and supports embryonic development and survival. This study aimed to investigate the underlying functions of Shh signaling in recurrent miscarriage (RM), a serious disorder of pregnancy. In the present study, Shh and Gli2 were mainly observed in cytotrophoblasts (CTBs), Ptch was mainly observed in syncytiotrophoblasts (STBs), and Smo and Gli3 were expressed in both CTBs and STBs. Shh signaling was significantly impaired in human placenta tissue from recurrent miscarriage patients compared to that of gestational age-matched normal controls. VEGF-A and CD31 protein levels were also significantly decreased in recurrent miscarriage patients. Furthermore, inhibition of Shh signaling impaired the motility of JAR cells by regulating the expression of Gli2 and Gli3. Intriguingly, inhibition of Shh signaling also triggered autophagy and autolysosome accumulation. Additionally, knockdown of BECN1 reversed Gant61-induced motility inhibition. In conclusion, our results showed that dysfunction of Shh signaling activated autophagy to inhibit trophoblast motility, which suggests the Shh pathway and autophagy as potential targets for RM therapy.Subject terms: Embryology, Endocrine reproductive disorders, Autophagosomes     

CeO2修饰Ni3S2纳米片用于高效电催化析氧

电化学水分解制氢作为重要的生产氢能的新能源技术,包括氢气析出反应(HER)和氧气析出反应(OER).然而,OER进行的是多步电子转移过程,动力学过程缓慢且过电位高,严重制约了电解水制氢的发展.因此开发低成本、高效稳定的非贵金属催化剂替代贵金属催化剂(RuO2,IrO2)来降低过电位,减少能源消耗十分必要.Ni3S2由于...