Scheme 2. (a) Lactide Polymerization Coinitiated by Carbohydrates; (b) Copolymerization of Lactone Derived from D-Gluconolactone and ε-Caprolactone (CL) Scheme 3. Polyesters Based on Pentitols and Pentaric Acid Scheme 4. Protein-Resistant Polyesters Based on Galactitol and D-Mannitol Scheme 5. Polyesters Based on L-Tartaric Acid Derivatives Scheme 6. PBS Copolyesters Based on L-Tartaric Acid Derivatives Scheme 7. Erythritol-Based Polyesters Containing Triazol Rings

Wish they all could be californium: X-ray absorption spectroscopy (black points) and Monte Carlo simulations (blue line) of CfIII in aqueous solutions have been combined to determine the ligand distance and coordination number (CN) of the CfIII aqua ion (see picture), the heaviest cation measured and simulated to date. The results confirm that a contraction takes place in the actinide series as in the lanthanide series

Schwergewicht: Röntgenabsorptionsspektroskopie (schwarze Punkte) und Monte‐Carlo‐Simulationen (blaue Linie) von CfIII in wässriger Lösung wurden kombiniert, um den Ligandenabstand und die Koordinationszahl (CN) im CfIII‐Aqua‐Ion, dem schwersten bislang gemessenen und simulierten Kation, zu bestimmen (siehe Bild). Die Ergebnisse stützen das Vorliegen einer Kontraktion in der Actinoidreihe wie in der Lanthanoidreihe.

The angular distribution function (ADF) associated with the oxygen-metal ion-oxygen angle (OMO) of several trivalent lanthanoid and actinoid aquaions has been used to identify the most probable coordination geometry of these aquaions in aqueous solutions. The ADFs extracted from the molecular dynamics trajectories have been compared with continuous distribution functions corresponding to the geometry of a reference polyhedron pattern. The procedure incorporates specific quantum-mechanical information on the aquaion under study. The new method is applied to the analysis of four M(HO) aquaions in water, M = Lu and Cf for n = 8, and M = La and Ac for n = 9. For those that are 8-coordinated, the square antiprism (SA) coordination geometry is preferred. For the 9-fold coordination, the simulation ADFs are more similar to the continuous ADF derived from a Gyro-elongated-SA rather than to the usually proposed trigonal tricapped prism. Advantages of these continuous distributions with respect to the usually employed discrete distributions are emphasized as well as further applications are suggested.

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The extensive use of oral dosage forms for the treatment of diseases may be linked to deficient pharmacokinetic properties. In some cases the drug is barely soluble; in others, the rapid transit of the formulation through the gastrointestinal tract (GIT) makes it difficult to achieve therapeutic levels in the organism; moreover, some drugs must act locally due to a gastric pathology, but the time they remain in the stomach is short. The use of formulations capable of improving all these parameters, as well as increasing the resident time in the stomach, has been the target of numerous research works, with low-density systems being the most promising and widely explored, however, there is further scope to improve these systems. There are a vast variety of polymeric materials used in low-density gastroretentive systems and a number of methods to improve the bioavailability of the drugs. This works aims to expedite the development of breakthrough approaches by providing an in-depth understanding of the polymeric materials currently used, both natural and synthetic, their properties, advantages, and drawbacks.

In the present work, we demonstrate the preparation of chitosan-based composites as vehicles of the natural occurring multi-drug resveratrol (RES). Such systems are endowed with potential therapeutic effects on inflammatory bowel diseases (IBD), such as Crohn’s disease (CD) and ulcerative colitis, through the sustained colonic release of RES from long-lasting mucoadhesive drug depots. The loading of RES into nanoparticles (NPs) was optimized regarding two independent variables: RES/polymer ratio, and temperature. Twenty experiments were carried out and a Box–Behnken experimental design was used to evaluate the significance of these independent variables related to encapsulation efficiency (EE). The enhanced RES EE values were achieved in 24 h at 39 °C and at RES/polymer ratio of 0.75:1 w/w. Sizes and polydispersities of the optimized NPs were studied by dynamic light scattering (DLS). Chitosan (CTS) dispersions containing the RES-loaded NPs were ionically gelled with tricarballylic acid to yield CTS-NPs composites. Macro- and microscopic features (morphology and porosity studied by SEM and spreadability), thermal stability (studied by TGA), and release kinetics of the RES-loaded CTS-NPs were investigated. Release patterns in simulated colon conditions for 48 h displayed significant differences between the NPs (final cumulative drug release: 79–81%), and the CTS-NPs composites (29–34%).

Articles you may be interested inCollecting high-order interactions in an effective pairwise intermolecular potential using the hydrated ion concept: The hydration of Cf 3+ This work proposes a new methodology to build interaction potentials between a highly charged metal cation and water molecules. These potentials, which can be used in classical computer simulations, have been fitted to reproduce quantum mechanical interaction energies (MP2 and BP86) for a wide range of [M(H 2 O) n ] m+ (H 2 O) clusters (n going from 6 to 10 and from 0 to 18). A flexible and polarizable water shell model (Mobile Charge Density of Harmonic Oscillator) has been coupled to the cation-water potential. The simultaneous consideration of poly-hydrated clusters and the polarizability of the interacting particles allows the inclusion of the most important many-body effects in the new polarizable potential. Applications have been centered on the californium, Cf(III) the heaviest actinoid experimentally studied in solution. Two different strategies to select a set of about 2000 structures which are used for the potential building were checked. Monte Carlo simulations of Cf(III)+500 H 2 O for three of the intermolecular potentials predict an aquaion structure with coordination number close to 8 and average R Cf-O in the range 2.43-2.48 Å, whereas the fourth one is closer to 9 with R Cf-O = 2.54 Å. Simulated EXAFS spectra derived from the structural Monte Carlo distribution compares fairly well with the available experimental spectrum for the simulations bearing 8 water molecules. An angular distribution similar to that of a square antiprism is found for the octa-coordination.