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91.
Jinseob Shin Kyomin Shin Hanna Lee Kyung-Do Suh Hyojung Kim Jin Woong Kim 《Colloid and polymer science》2012,290(6):553-559
This paper describes a useful means of noninvasively enhancing transdermal delivery efficiency. For this, chitosan nanocapsules
with positive surface charges were fabricated by using the in situ precipitation method. These nanocapsules cannot only have
an ability to encapsulate the drug molecule (this study used riboflavin 5′-monophosphate), but also electrotatically interact
with the stratum corneum layer. To demonstrate this, fluorescence-labeled polymer nanoparticles with different particle sizes
as well as surface charges were topically applied onto the skin and their distribution was directly imaged. This demonstration
experiment allowed us to figure out that once the nanocapsules were provided with positive surface charges, they readily deposited
into the stratum corneum layer due to the electrostatic interaction. Further quantitative characterization of the penetrating
amount of riboflavin 5′-monophosphate by using the Frantz diffusion cell method showed that our chitosan nanocapsule system
effectively improved transdermal delivery efficiency. 相似文献
92.
L. Gillo S. E. Golbreich T. Nagoshi I. Nakagawa C. S. Piper W. C. Campbell Marion I. Hanna L. Palfray C. Rocchi R. del Monte R. Lechner M. Roß L. A. Ynalvez H. Lecoq Th. A. G. Haanappel Thérèse Jullig J. Barbière A. Lecco L. Lilic P. M. Heertjes 《Analytical and bioanalytical chemistry》1943,125(3-4):133-137
93.
We investigate the elasticity of two types of single-stranded synthetic DNA homopolydeoxynucletides, poly(dA) and poly(dT), by AFM-based single-molecule force spectroscopy. We find that poly(dT) exhibits the expected entropic elasticity behavior, while poly(dA) unexpectedly displays two overstretching transitions in the force-extension relationship. We suggest that these transitions, which occur at approximately 23 pN and approximately 113 pN, directly capture, for the first time, the mechanical signature of base-stacking interactions among adenines in DNA, in the absence of base pairing. 相似文献
94.
Boudeile J Druon F Hanna M Georges P Zaouter Y Cormier E Petit J Goldner P Viana B 《Optics letters》2007,32(14):1962-1964
We demonstrate the generation of 68 fs secant hyperbolic pulses at a 105 MHz repetition rate with an average power of 520 mW from a diode-pumped Yb(3+):CaGdAlO(4) mode-locked laser. A semiconductor saturable absorber allows passive mode locking, and a 15 W diode laser is used to pump directly the crystal. To our knowledge this represents the highest average power ever obtained for a sub-100 fs diode-pumped Yb-bulk laser. 相似文献
95.
Origin of the failure of classical nucleation theory: incorrect description of the smallest clusters
We carry out molecular Monte Carlo simulations of clusters in an imperfect vapor. We show that down to very small cluster sizes, classical nucleation theory built on the liquid drop model can be used very accurately to describe the work required to add a monomer to the cluster. However, the error made in modeling the smallest of clusters as liquid drops results in an erroneous absolute value for the cluster work of formation throughout the size range. We calculate factors needed to correct the cluster formation work given by the liquid drop model. The corrected work of formation results in nucleation rates in good agreement with recent nucleation experiments on argon and water. 相似文献
96.
Hanna Luhavaya Dr. Marcio V. B. Dias Simon R. Williams Dr. Hui Hong Prof. Luciana G. de Oliveira Prof. Peter F. Leadlay 《Angewandte Chemie (International ed. in English)》2015,54(46):13622-13625
Tetrahydropyran rings are a common feature of complex polyketide natural products, but much remains to be learned about the enzymology of their formation. The enzyme SalBIII from the salinomycin biosynthetic pathway resembles other polyether epoxide hydrolases/cyclases of the MonB family, but SalBIII plays no role in the conventional cascade of ring opening/closing. Mutation in the salBIII gene gave a metabolite in which ring A is not formed. Using this metabolite in vitro as a substrate analogue, SalBIII has been shown to form pyran ring A. We have determined the X‐ray crystal structure of SalBIII, and structure‐guided mutagenesis of putative active‐site residues has identified Asp38 and Asp104 as an essential catalytic dyad. The demonstrated pyran synthase activity of SalBIII further extends the impressive catalytic versatility of α+β barrel fold proteins. 相似文献
97.
98.
Studies on the collision‐induced dissociation of adipoR agonists after electrospray ionization and their implementation in sports drug testing 下载免费PDF全文
Josef Dib Nils Schlörer Wilhelm Schänzer Mario Thevis 《Journal of mass spectrometry : JMS》2015,50(2):407-417
AdipoR agonists are small, orally active molecules capable of mimicking the protein adiponectin, which represents an adipokine with antidiabetic and antiatherogenic effects. Two adiponectin receptors were reported in the literature referred to as adipoR1 and adipoR2. Activation of these receptors stimulates mitochondrial biogenesis and results in an improved oxidative metabolism (via adipoR1) and increased insulin sensitivity (via adipoR2). Hence, adipoR agonists are potentially performance enhancing substances and targets of proactive and preventive anti‐doping measures. In this study, two adipoR agonists termed AdipoRon and 112254 as well as two isotopically labeled internal standards (ISTDs) were synthesized in three‐step reactions. The products were fully characterized by nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS) and density functional theory (DFT) computation. Collision‐induced dissociation pathways following electrospray ionization were suggested based on the determined elemental compositions of product ions, comparison to product ions derived from labeled analogs (ISTDs), H/D‐exchange experiments and the results of DFT calculations. The most abundant product ions were found at m/z 174, tentatively assigned to protonated 1‐benzyl‐1,2,3,4‐tetrahydropyridine for AdipoRon, and m/z 207, suggested as protonated 1‐(4‐methoxybenzyl)piperazine, for 112254. Notably, the loss of the heterocyclic ring (i.e. piperazine and piperidine, respectively) in a supposedly intramolecular elimination reaction was observed in both cases. A qualitative determination of both AdipoR agonists in human plasma was established and fully validated for doping control purposes. Validation items such as recovery (86–89%), specificity, linearity, lower limit of detection (1 ng/ml), intraday (3–18%) and interday (5–16%) precision as well as ion suppression or enhancement were determined. Based on these findings adipoR agonists can be implemented in sports drug testing procedures. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
99.
100.
Jürgen Brem Weston B. Struwe Anna M. Rydzik Hanna Tarhonskaya Inga Pfeffer Emily Flashman Sander S. van Berkel James Spencer Timothy D. W. Claridge Michael A. McDonough Justin L. P. Benesch Christopher J. Schofield 《Chemical science》2015,6(2):956-963
Metallo-β-lactamases (MBLs) catalyse the hydrolysis of almost all β-lactam antibiotics. We report biophysical and kinetic studies on the São Paulo MBL (SPM-1), which reveal its Zn(ii) ion usage and mechanism as characteristic of the clinically important di-Zn(ii) dependent B1 MBL subfamily. Biophysical analyses employing crystallography, dynamic 19F NMR and ion mobility mass spectrometry, however, reveal that SPM-1 possesses loop and mobile element regions characteristic of the B2 MBLs. These include a mobile α3 region which is important in catalysis and determining inhibitor selectivity. SPM-1 thus appears to be a hybrid B1/B2 MBL. The results have implications for MBL evolution and inhibitor design. 相似文献