Self-Assembling Supramolecular Hybrid Hydrogel Beads

With the goal of imposing shape and structure on supramolecular gels, we combine a low molecular weight gelator (LMWG) with the polymer gelator (PG) calcium alginate in a hybrid hydrogel. By imposing thermal and temporal control of the orthogonal gelation methods, the system either forms an extended inter-penetrating network or core-shell structured gel beads – a rare example of a supramolecular gel formulated inside discrete gel spheres. The self-assembled LMWG retains its unique properties within the beads, such as remediating Pd(II) and reducing it in situ to yield catalytically-active Pd(0) nanoparticles. A single PdNP-loaded gel bead can catalyse the Suzuki-Miyaura reaction, constituting a simple and easy-to-use reaction dosing form. These unique shaped and structured LMWG-filled gel beads are a versatile platform technology, with great potential in a range of applications

Self‐Assembled Gels formed in Deep Eutectic Solvents : Supramolecular Eutectogels with High Ionic Conductivities

This paper reports the ability of 1,3:2,4‐dibenzylidene‐D‐ sorbitol (DBS), a simple, commercially‐relevant compound, to self‐assemble as a result of intermolecular non‐covalent interactions into supramolecular gels in deep eutectic solvents (DESs). The DESs are based on choline chloride combined with alcohols/ureas – DBS forms gels at a loading of 5% wt/vol. Rheology confirms the gel‐like nature of the materials, electron microscopy indicates underpinning nanofibrillar DBS networks and differential scanning calorimetry shows the deep eutectic solvent nature of the liquid‐like phase is retained. The ionic conductivities of the gels are similar to those of the unmodified DESs proving the deep eutectic nature of the ionic liquid‐like phase. Gelation is tolerant of ionic additives Li+, Mg2+ and Ca2+, with the resulting gels having similar conductivities to electrolyte dissolved in the native DES. The low‐molecular‐weight gelator DBS is a low‐cost additive – forming gels in DESs from readily‐available constituents, with conductivity levels suitable for practical applications. We suggest supramolecular eutectogels have potential uses ranging from energy technology to synthesis and catalysis

Palladium-scavenging self-assembled hybrid hydrogels – reusable highly-active green catalysts for Suzuki–Miyaura cross-coupling reactions

A hybrid hydrogel based on 1,3:2,4-dibenzylidene sorbitol (DBS) modified with acyl hydrazides combined with agarose was used for in situ reduction and binding of palladium from aqueous mixtures without the need for an external reducing agent. Palladium uptake was monitored and the formation of Pd nanoparticles (PdNPs) trapped within the gel and located close to the nanofibres was confirmed. This gel effectively scavenges palladium from solution to concentrations 10 times). Reactions were purified by simple washing protocols, and leaching of Pd from the gels is limited (<1 ppm). The gels were also used in flow-through mode, giving efficient, rapid reactions, with easy work-up. These catalytic gels combine advantages of homogeneous and heterogeneous catalysts-they are solvent compatible with the reaction taking place in a solution-like environment, while the solid-like gel network enables catalyst recycling. In summary, these hydrogels scavenge 'waste' palladium and convert it into gel 'wealth' capable of efficient, environmentally-friendly Suzuki-Miyaura catalysis

Organolithium Gels – Simple Easily Divided Delivery Vehicles for Highly Reactive Species

Organolithium reagents are a vital tool in modern organic chemistry allowing the synthesis of new carbon-carbon bonds. However, due to the high reactivity of organolithiums, the use of low temperatures, inert atmospheres and strictly dried solvents are usually necessary. Here, we report a new encapsulating method for the stabilisation of the sensitive organolithium reagents, PhLi and BuLi (n-BuLi), within a low-cost hexatriacontane (C36H74) organogel. The use of this technology is showcased in nucleophilic addition reactions under ambient conditions, low-temperature bromine-lithium exchange and CH functionalisation reactions. The gel significantly enhances the stability of these organolithiums, allows simple handling, delivery and storage, and enables reproducible reagent portioning. The use of gels as easily divided delivery vehicles for hazardous organometallic reagents has the potential to revolutionise this area of synthetic chemistry, making these powerful reactions safer and more accessible to non-specialist researchers, enabling the more widespread use of these common synthetic methods

Organogel delivery vehicles for the stabilization of organolithium reagents

Organolithium reagents are a vital tool in modern organic chemistry, enabling the synthesis of carbon–carbon bonds. However, due to their high reactivity, low temperatures, inert atmospheres and strictly dried solvents are usually necessary for their use. Here we report an encapsulating method for the stabilization of sensitive organolithium reagents—PhLi, n-BuLi and s-BuLi—in a low-cost hexatriacontane (C36H74) organogel. The use of this technology is showcased in nucleophilic addition reactions under ambient conditions, low-temperature bromine–lithium exchange, ortho-lithiation and C–H functionalization. The gel substantially enhances organolithium stability, allows simple storage, handling and delivery, and enables reproducible reagent portioning. The use of gels as easily divided delivery vehicles for hazardous organometallics has the potential to transform this area of synthetic chemistry, making these powerful reactions safer and more accessible to non-specialist researchers, and enabling the more widespread use of these common synthetic methods

Influence of organic versus inorganic dietary selenium supplementation on the concentration of selenium in colostrum, milk and blood of beef cows

<p>Abstract</p> <p>Background</p> <p>Selenium (Se) is important for the postnatal development of the calf. In the first weeks of life, milk is the only source of Se for the calf and insufficient level of Se in the milk may lead to Se deficiency. Maternal Se supplementation is used to prevent this.</p> <p>We investigated the effect of dietary Se-enriched yeast (SY) or sodium selenite (SS) supplements on selected blood parameters and on Se concentrations in the blood, colostrum, and milk of Se-deficient Charolais cows.</p> <p>Methods</p> <p>Cows in late pregnancy received a mineral premix with Se (SS or SY, 50 mg Se per kg premix) or without Se (control – C). Supplementation was initiated 6 weeks before expected calving. Blood and colostrum samples were taken from the cows that had just calved (Colostral period). Additional samples were taken around 2 weeks (milk) and 5 weeks (milk and blood) after calving corresponding to Se supplementation for 6 and 12 weeks, respectively (Lactation period) for Se, biochemical and haematological analyses.</p> <p>Results</p> <p>Colostral period. Se concentrations in whole blood and colostrum on day 1 <it>post partum </it>and in colostrum on day 3 <it>post partum </it>were 93.0, 72.9, and 47.5 μg/L in the SY group; 68.0, 56.0 and 18.8 μg/L in the SS group; and 35.1, 27.3 and 10.5 μg/L in the C group, respectively. Differences among all the groups were significant (<it>P </it>< 0.01) at each sampling, just as the colostrum Se content decreases were from day 1 to day 3 in each group. The relatively smallest decrease in colostrum Se concentration was found in the SY group (<it>P </it>< 0.01).</p> <p>Lactation period. The mean Se concentrations in milk in weeks 6 and 12 of supplementation were 20.4 and 19.6 μg/L in the SY group, 8.3 and 11.9 μg/L in the SS group, and 6.9 and 6.6 μg/L in the C group, respectively. The values only differed significantly in the SS group (<it>P </it>< 0.05). The Se concentrations in the blood were similar to those of cows examined on the day of calving. The levels of glutathione peroxidase (GSH-Px) activity were 364.70, 283.82 and 187.46 μkat/L in the SY, SS, and C groups, respectively. This was the only significantly variable biochemical and haematological parameter.</p> <p>Conclusion</p> <p>Se-enriched yeast was much more effective than sodium selenite in increasing the concentration of Se in the blood, colostrum and milk, as well as the GSH-Px activity.</p

Repeated bedside echocardiography in children with respiratory failure

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to verify the benefits and limitations of repeated bedside echocardiographic examinations in children during mechanical ventilation. For the purposes of this study, we selected the data of over a time period from 2006 to 2010.</p> <p>Methods</p> <p>A total of 235 children, average age 3.21 (SD 1.32) years were included into the study and divided into etiopathogenic groups. High-risk groups comprised: Acute lung injury and acute respiratory distress syndrome (ALI/ARDS), return of spontaneous circulation after cardiopulmonary resuscitation (ROSC), bronchopulmonary dysplasia (BPD), cardiomyopathy (CMP) and cardiopulmonary disease (CPD). Transthoracic echocardiography was carried out during mechanical ventilation. The following data were collated for statistical evaluation: right and left ventricle myocardial performance indices (RV MPI; LV MPI), left ventricle shortening fraction (SF), cardiac output (CO), and the mitral valve ratio of peak velocity of early wave (E) to the peak velocity of active wave (A) as E/A ratio. The data was processed after a period of recovery, i.e. one hour after the introduction of invasive lines (time-1) and after 72 hours of comprehensive treatment (time-2). The overall development of parameters over time was compared within groups and between groups using the distribution-free Wilcoxons and two-way ANOVA tests.</p> <p>Results</p> <p>A total of 870 echocardiographic examinations were performed. At time-1 higher average values of RV MPI (0.34, SD 0.01 vs. 0.21, SD 0.01; p < 0.001) were found in all groups compared with reference values. Left ventricular load in the high-risk groups was expressed by a higher LV MPI (0.39, SD 0.13 vs. 0.29, SD 0.02; p < 0.01) and lower E/A ratio (0.95, SD 0.36 vs. 1.36, SD 0.64; p < 0.001), SF (0.37, SD 0.11 vs. 0.47, SD 0.02; p < 0.01) and CO (1.95, SD 0.37 vs. 2.94, SD 1.03; p < 0.01). At time-2 RV MPI were lower (0.25, SD 0.02 vs. 0.34, SD 0.01; p < 0.001), but remained higher compared with reference values (0.25, SD 0.02 vs. 0.21, SD 0.01; p < 0.05). Other parameters in high-risk groups were improved, but remained insignificantly different compared with reference values.</p> <p>Conclusion</p> <p>Echocardiography complements standard monitoring of valuable information regarding cardiac load in real time. Chest excursion during mechanical ventilation does not reduce the quality of the acquired data.</p