Characterization of Pt/SBA-15 prepared by the deposition–precipitation method

Mesoporous silica SBA-15 was prepared and loaded with Pt using the deposition–precipitation method (DP). The Pt loaded material was characterized by N₂ sorption, and X-ray diffraction (XRD) at low scattering angles as well as XRD at wide angles, in order to monitor the impact of the metal deposition pathway on the mesoporous texture. After DP the material contains ordered mesoporous silica as well as a fraction appearing as non-ordered amorphous silica. This is most likely caused by the hydrothermal treatment involved in the DP. The material was also characterized using NIR and ²⁹Si MAS NMR spectroscopy. The NIR results of the calcined materials indicate that the silanol groups of SBA-15 may act as anchoring groups for the metallic Pt particles. The NMR spectroscopy data shows that the Pt/SBA-15 sample prepared by the DP method posseses a better short-range regularity of SBA-15 walls as compared to the parent SBA-15. This is suggested to be caused by dissolution and possible re-precipitation of siliceous species.     

Probing enzyme promiscuity of SGNH hydrolases

Several hydrolases of the SGNH superfamily, including the lipase SrLip from Streptomyces rimosus (Q93MW7), the acyl-CoA thioesterase I TesA from Pseudomonas aeruginosa (Q9HZY8) and the two lipolytic enzymes EstA (from P. aeruginosa, O33407) and EstP (from Pseudomonas putida, Q88QS0), were examined for promiscuity. These enzymes were tested against four chemically different classes of a total of 34 substrates known to be hydrolysed by esterases, thioesterases, lipases, phospholipases, Tweenases and proteases. Furthermore, they were also analysed with respect to their amino acid sequences and structural homology, and their phylogenetic relationship was determined. The Pseudomonas esterases EstA and EstP each have an N-terminal domain with catalytic activity together with a C-terminal autotransporter domain, and so the hybrid enzymes EstA(N)-EstP(C) and EstP(N)-EstA(C) were constructed by swapping the corresponding N- and C-terminal domains, and their hydrolytic activities were compared. Interestingly, substrate specificity and kinetic measurements indicated a significant influence of the autotransporter domains on the catalytic activities of these enzymes in solution. TesA, EstA and EstP were shown to function as esterases with different affinities and catalytic efficacies towards p-nitrophenyl butyrate. Of all the enzymes tested, only SrLip revealed lipase, phospholipase, esterase, thioesterase and Tweenase activities.     

The Chemistry of the Postpharyngeal Gland of Female European Beewolves

Females of the European beewolf, Philanthus triangulum, possess a large glove-shaped gland in the head, the postpharyngeal gland (PPG). They apply the content of the PPG to their prey, paralyzed honeybees, where it delays fungal infestation. Here, we describe the chemical composition of the gland by using combined GC-MS, GC-FTIR, and derivatization. The PPG of beewolves contains mainly long-chain unsaturated hydrocarbons (C23–C33), lower amounts of saturated hydrocarbons (C14–C33), and minor amounts of methyl-branched hydrocarbons (C17–C31). Additionally, the hexane-soluble gland content is comprised of small amounts of an unsaturated C25 alcohol, an unknown sesquiterpene, an octadecenylmethylester, and several long-chain saturated (C25, C27) and unsaturated (C23–C27) ketones, some of which have not yet been reported as natural products. Surprisingly, we found a dimorphism with regard to the major component of the PPG with some females having (Z)-9-pentacosene, whereas others have (Z)-9-heptacosene as their predominant component. The biological relevance of the compounds for the prevention of fungal growth on the prey and the significance of the chemical dimorphism are discussed.     

ZSM-5 zeolite films on Si substrates grown by in situ seeding and secondary crystal growth and application in an electrochemical hydrocarbon gas sensor

ZSM-5 zeolite films were grown on Si substrates by a two-step hydrothermal synthesis consisting of in situ seeding and secondary crystal growth. The films were 8–13 μm thick and partly oriented with the c-axis perpendicular to the substrate surface. After ion exchange with sodium ions, one film was applied as solid electrolyte in a potentiometric hydrocarbon gas sensor. A fast and reversible voltage response of the sensor to varying propane concentrations (100 ppm – 10%) was observed in O₂/CO₂/N₂ gas mixtures at 723 K.     

Selective Oxidation of Propene with Air to Propylene Oxide,a Case Study of Autoxidation Versus Catalytic Oxidation with AMM-Catalysts

The formation of propylene oxide from propene by direct oxidation with air has been studied with a series of new microporous amorphous catalysts containing isolated active sites. Although the materials showed good activities as heterogeneous oxidation catalysts, the formation of acroleine dominated in the gas phase. Oxidation selectivities of the various catalysts are reported. Significant PO-formation was only observed under reaction conditions involving pressures larger 5 bar. Promoting effects of solvents or additives like acetaldehyde could be excluded. Best results were observed in continuous gas phase flow experiments. All catalysts studied proved detrimental to the PO-yield and control experiments pointed to catalyst free autoxidation conditions. A factorial design followed by an optimization of the reaction conditions provided PO-selectivities of 60 % at propene conversion of 11.4 % (T = 290 °C; pressure = 25 bar; propene content = 75 %; total feed = 39.5 ml/min) at continuous reaction conditions. By passivating the inner reactor surfaces with gold, a PO-selectivity of 62.8 % at a propene conversion of 15.1 % could be obtained, indicating, that autoxidation of propene may become a serious contender in the search for improved production processes. This work is a case study of attempted catalyzed selective oxidation with air illustrating potential pitfalls and misleading interpretations.     

Effect of self-complementary motifs on phase compatibility and material properties in blends of supramolecular polymers

Applicability of supramolecular polymers blending in preparation of materials with tunable properties is reported. The effect of strongly dimerising 2-ureido-4[1H]-pyrimidinone (UPy) end groups on phase compatibility in binary polymer blends was studied. A low molecular weight poly(tetrahydrofuran) diol was functionalized with UPy moieties (PTHF(UPy)₂, a soft material) and mixed with varying amounts of low molecular weight UPy functionalized polycaprolactone di- and triol (PCL(UPy)₂ and PCL(UPy)₃, both relatively strong and stiff materials). Thermal studies showed that T_g of the homopolymers shifted to intermediate temperatures. AFM observation suggested that the phase domain decreased significantly after UPy functionalization of diols. Also the mechanical properties improved at a higher rate than those predicted by the rule of mixtures. These findings indicate that blend components are placed in intimate contact as a result of the UPy-UPy interactions. The reversible crosslinking by PCL(UPy)₃ gave better control still over the mechanical properties of the supramolecular polymer blends.     

Inflammation in the Human Periodontium Induces Downregulation of the α1- and β1-Subunits of the sGC in Cementoclasts

Nitric oxide (NO) binds to soluble guanylyl cyclase (sGC), activates it in a reduced oxidized heme iron state, and generates cyclic Guanosine Monophosphate (cGMP), which results in vasodilatation and inhibition of osteoclast activity. In inflammation, sGC is oxidized and becomes insensitive to NO. NO- and heme-independent activation of sGC requires protein expression of the α₁- and β₁-subunits. Inflammation of the periodontium induces the resorption of cementum by cementoclasts and the resorption of the alveolar bone by osteoclasts, which can lead to tooth loss. As the presence of sGC in cementoclasts is unknown, we investigated the α₁- and β₁-subunits of sGC in cementoclasts of healthy and inflamed human periodontium using double immunostaining for CD68 and cathepsin K and compared the findings with those of osteoclasts from the same sections. In comparison to cementoclasts in the healthy periodontium, cementoclasts under inflammatory conditions showed a decreased staining intensity for both α₁- and β₁-subunits of sGC, indicating reduced protein expression of these subunits. Therefore, pharmacological activation of sGC in inflamed periodontal tissues in an NO- and heme-independent manner could be considered as a new treatment strategy to inhibit cementum resorption.     

Treatment of Stress Urinary Incontinence with Muscle Stem Cells and Stem Cell Components: Chances,Challenges and Future Prospects

Urinary incontinence (UI) is a major problem in health care and more than 400 million people worldwide suffer from involuntary loss of urine. With an increase in the aging population, UI is likely to become even more prominent over the next decades and the economic burden is substantial. Among the different subtypes of UI, stress urinary incontinence (SUI) is the most prevalent and focus of this review. The main underlying causes for SUI are pregnancy and childbirth, accidents with direct trauma to the pelvis or medical treatments that affect the pelvic floor, such as surgery or irradiation. Conservative approaches for the treatment of SUI are pelvic physiotherapy, behavioral and lifestyle changes, and the use of pessaries. Current surgical treatment options include slings, colposuspensions, bulking agents and artificial urinary sphincters. These treatments have limitations with effectiveness and bear the risk of long-term side effects. Furthermore, surgical options do not treat the underlying pathophysiological causes of SUI. Thus, there is an urgent need for alternative treatments, which are effective, minimally invasive and have only a limited risk for adverse effects. Regenerative medicine is an emerging field, focusing on the repair, replacement or regeneration of human tissues and organs using precursor cells and their components. This article critically reviews recent advances in the therapeutic strategies for the management of SUI and outlines future possibilities and challenges.