The study investigates the chemical stability of lipids used as excipients in the production of solid lipid nanoparticles (SLN). A total of 17 SLN formulations was produced using different lipids. ...Most of the formulations were produced using identical binary surfactant mixtures and concentrations to study the effect of the chemical nature of the lipid on its stability in SLN. In some formulations surfactants were exchanged to study the contribution of the surfactant. The particles were characterised by photon correlation spectroscopy, laser diffractometry, zeta potential determination and differential scanning calorimetry, the latter to assess potential effects of lipid crystallinity and modifications on lipid stability. Lipid analysis was performed by gas chromatography using a sampling preparation and analysis procedure especially developed for SLN. This short-term study provides primarily information about the stability of the lipid under production conditions, that means high pressure homogenisation (cavitation) at high temperature. No degradation products couldbe detected for all lipids, the production process itself did not impair excipient stability.
Stable microemulsions oil-in-water (o/w) and water-in-oil (w/o) with timolol were obtained. These formulations were sterilized using two methods: by autoclaving and by sterile filtering according to ...the Polish Pharmacopeia V. Microemulsions were kept in the temperatures of 25 degrees C and 5 degrees C during three months. The following physical parameters were investigated: density, dynamic viscosity, refractive index, surface tension, pH and osmotic tension. All the microemulsions met the requirements for eye drops.
Previous multiple regression analyses of the solar cycle variation of stratospheric ozone are improved by (1) analyzing three independent satellite ozone data sets with lengths extending up to 25 ...years and (2) comparing column ozone measurements with ozone profile data during the 1992–2003 period when no major volcanic eruptions occurred. Results show that the vertical structure of the tropical ozone solar cycle response has been consistently characterized by statistically significant positive responses in the upper and lower stratosphere and by statistically insignificant responses in the middle stratosphere (∼28–38 km altitude). This vertical structure differs from that predicted by most models. The similar vertical structure in the tropics obtained for separate time intervals (with minimum response invariably near 10 hPa) is difficult to explain by random interference from the QBO and volcanic eruptions in the statistical analysis. The observed increase in tropical total column ozone approaching the cycle 23 maximum during the late 1990s occurred primarily in the lower stratosphere below the 30 hPa level. A mainly dynamical origin for the solar cycle total ozone variation at low latitudes is therefore likely. The amplitude of the solar cycle ozone variation in the tropical upper stratosphere derived here is somewhat reduced in comparison to earlier results. Additional data are needed to determine whether this upper stratospheric response is or is not larger than model estimates.
Given two ordinary elliptic curves over a finite field
having the same cardinality and endomorphism ring, it is known that
the curves admit a nonzero isogeny between them, but finding such an
isogeny ...is believed to be computationally difficult. The fastest
known classical algorithm takes exponential time, and prior to our
work no faster quantum algorithm was known. Recently, public-key
cryptosystems based on the presumed hardness of this problem have
been proposed as candidates for post-quantum cryptography. In this
paper, we give a new subexponential-time quantum algorithm for
constructing nonzero isogenies between two such elliptic curves,
assuming the Generalized Riemann Hypothesis (but with no other
assumptions). Our algorithm is based on a reduction to a hidden
shift problem, and represents the first nontrivial application of
Kuperberg's quantum algorithm for finding hidden shifts. This
result suggests that isogeny-based cryptosystems may be
uncompetitive with more mainstream quantum-resistant cryptosystems
such as lattice-based cryptosystems. As part of this work, we also
present the first classical algorithm for evaluating isogenies
having provably subexponential running time in the cardinality
of the base field under GRH.
The origin of the tropical lower-stratospheric response to 11-yr solar forcing and its possible coupling to a troposphere-ocean response is investigated using multiple linear regression (MLR) ...analyses of stratospheric ozone and temperature data over the 1979-2009 period and tropospheric sea level pressure (SLP) data over the 1880-2009 period. Stratospheric MLR results, comparisons with simulations from a chemistry-climate model, and analyses of decadal variations of meridional eddy heat flux indicate that the tropical lower-stratospheric response is produced mainly by a solar-induced modulation of the Brewer-Dobson circulation (BDC), with a secondary contribution from the Hadley circulation in the lowermost stratosphere. MLR analyses of long-term SLP data confirm previous results indicating a distinct positive response, on average, during the northern winter season in the North Pacific. The mean response in the Northern Hemisphere resembles a positive Arctic Oscillation mode and can also be characterized as "La Nina-like," implying a reduction of Rossby wave forcing, a weakening of the BDC, and an increase in tropical lower-stratospheric ozone and temperature near solar maxima. However, MLR analyses of different time periods show that the Pacific SLP response is not always present during every cycle; it was most clearly detected mainly during the ~1938-93 period when 11-yr solar variability was especially strong. During the 1979-93 period, the SLP response was strongly present when the lower-stratospheric responses were large. But during the 1994-2009 period, the SLP response was much less significant and the lower-stratospheric responses were weak, supporting the hypothesis that the lower-stratospheric and surface climate responses are dynamically coupled.
Laccase was earlier wired to yield an O2 electroreduction catalyst greatly outperforming platinum and its alloys. Here we describe the design, synthesis optimization of the composition, and ...characterization of the +0.55 V (AgAgCl) laccase-wiring redox hydrogel, with an apparent electron diffusion coefficient (D(app)) of 7.6 x 10(-7) cm2 s(-1). The high D(app) results in the tethering of redox centers to the polymer backbone through eight-atom-long spacer arms, which facilitate collisional electron transfer between proximal redox centers. The O2 flux-limited, true-area-based current density was increased from the earlier reported 560 to 860 microA cm(-2). When the O2 diffusion to the 7-microm-diameter carbon fiber cathode was cylindrical, half of the O2 flux-limited current was reached already at 0.62 V and 90% at 0.56 V vs Ag/AgCl, merely -0.08 and -0.14 V versus the 0.7 V (Ag/AgCl) reversible O2/H2O half-cell potential at pH 5.
Password authenticated key establishment (PAKE) is a cryptographic primitive that allows two parties who share a low-entropy secret (a password) to securely establish cryptographic keys in the ...absence of public key infrastructure. We propose the first quantum-resistant password-authenticated key exchange scheme based on supersingular elliptic curve isogenies. The scheme is built upon supersingular isogeny Diffie-Hellman
, and uses the password to generate permutations which obscure the auxiliary points. We include elements of a security proof, and discuss roadblocks to obtaining a proof in the BPR model
. We also include some performance results.
The paper is devoted to the investigation of chemical stability of lipids used as excipients in the production of Solid Lipid Nanoparticles (SLN). Different lipids and amounts of surfactants were ...considered. Most of the formulations were produced using identical binary surfactant mixtures and concentrations to analyze the effect of the chemical nature of the lipids on their stability in SLN. In some formulations, surfactants were exchanged or their concentration was increased to assess the contribution of surfactants on stability of lipids particles. Solid Lipid Nanoparticles were characterized by photon correlation spectroscopy, laser diffractometry, zeta potential determination and differential scanning calorimetry. Potential effects of lipid crystallinity and modifications were assessed. A gas chromatography (GC) analysis in combination with a method for lipid extraction from aqueous SLN dispersions was used to investigate the chemical stability of the lipid excipients forming the particle matrix. All formulations were produced by the hot homogenization technique. The production process of SLN itself did not affect the chemical stability of lipid excipient forming the particle matrix. The formulations where lipids consisted of trigylicerides showed a negligible decomposition of the structure during incubation at 25 °C. Dynasan 118 showed the highest chemical stability (loss
<
4%) within two years.
A decadal variation of tropical lower stratospheric ozone and temperature has previously been identified that correlates positively with the 11 year solar activity cycle. However, the El ...Niño–Southern Oscillation (ENSO) also influences lower stratospheric ozone and temperature. It is therefore legitimate to ask whether quasi‐decadal ENSO variability can contribute to this apparent solar cycle variation, either accidentally because of the short measurement record or physically because solar variability affects ENSO. Here we present multiple regression analyses of available data records to compare differences in results obtained with and without including an ENSO term in the statistical model. In addition, simulations are performed using the NRL NOGAPS‐ALPHA GCM for warm/cold ENSO conditions to test for consistency with the ENSO regression results. We find only very minor changes in annual mean solar regression coefficients when an ENSO term is included. However, the observed tropical ENSO response provides useful insights into the origin of the unexpected vertical structure of the tropical solar cycle ozone response. In particular, the ENSO ozone response is negative in the lower stratosphere due to increased upwelling but changes sign, becoming positive in the middle stratosphere (5–10 hPa) due mainly to advective decreases of temperature and NOx, which photochemically increase ozone. A similar mechanism may explain the observed lower stratospheric solar cycle ozone and temperature response and the absence of a significant response in the tropical middle stratosphere.
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