A photochemical route for efficient cyclopeptide formation with a minimum of protection and activation chemistry

An elaborated protocol is described which allows the efficient transformation of di-, tri-, and tetrapeptides into cyclopeptides with a minimum of protection and activation chemistry using the photoinduced electron transfer initiated decarboxylation of N-phthaloyl peptides resulting in C-C coupling between the initially formed carbon radicals.     

Growth of iron cobalt oxides by atomic layer deposition

Thin films of iron cobalt oxides with spinel-type structure are made by the atomic layer deposition (ALD) technique using Fe(thd)3 (Hthd = 2,2,6,6-tetramethylheptane-3,5-dione), Co(thd)2, and ozone as precursors. Pulse parameters for ALD-type growth are established and such growth can be achieved at deposition temperatures between 185 and 310 degrees C. Films have been deposited on amorphous soda-lime glass and single-crystalline substrates of Si(100), MgO(100), and alpha-Al2O3(001) which all provide crystalline films, but with various orientations and crystallite sizes. Application of an external magnetic field during the film growth does not influence film growth characteristics (growth rate, crystallinity, topography etc.). Magnetization data are reported for phase-pure films of spinel-type structure with composition Fe2CoO4.     

A modified surface forces apparatus for single molecule tracking

To unravel molecular motion within confined liquids, we have combined a surface forces apparatus (SFA) with a highly sensitive fluorescence microscope. Details of our setup including important modifactions to enable the tracking of single dye molecules within nanometer thin confined liquid films are presented. The mechanical and optical performance of our setup is discussed in detail. For a load of 20 mN we observed a circular-shaped contact region (d approximately 300 microm), which results in a confining pressure of about 280 kPa. First experiments on liquid films of tetrakis(2-ethylhexoxy)silane (TEHOS) doped with rhodamine B demonstrated the ability to track single dye molecules within the confining gap of a SFA. The mean diffusion constant was independent of the liquid film thickness of approximately 3x10(-8) cm2/s and thus 10 times smaller than the diffusion constant of rhodamine B in bulk TEHOS. This points to the existence of a thin interface layer with slower molecular dynamics and an attractive potential parallel to the solid surface trapping molecules in this interface region.     

Asymmetric Synthesis of Fully Substituted Cyclopentane‐Oxindoles through an Organocatalytic Triple Michael Domino Reaction

An efficient, highly stereoselective asymmetric synthesis of fully functionalized cyclopentanes bearing an oxindole moiety and several other functional groups in one pot has been developed. Key step is an organocatalytic triple Michael domino reaction forming three C?C bonds and six stereocenters, including a quaternary one. Starting from equimolar amounts of simple substrates, a high molecular complexity can be reached after a Wittig olefination in one pot. The new protocol can easily be scaled up to gram amounts.     

Discovery and validation of urinary exposure markers for different plant foods by untargeted metabolomics

While metabolomics is increasingly used to investigate the food metabolome and identify new markers of food exposure, limited attention has been given to the validation of such markers. The main objectives of the present study were to (1) discover potential food exposure markers (PEMs) for a range of plant foods in a study setting with a mixed dietary background and (2) validate PEMs found in a previous meal study. Three-day weighed dietary records and 24-h urine samples were collected three times during a 6-month parallel intervention study from 107 subjects randomized to two distinct dietary patterns. An untargeted UPLC-qTOF-MS metabolomics analysis was performed on the urine samples, and all features detected underwent strict data analyses, including an iterative paired t test and sensitivity and specificity analyses for foods. A total of 22 unique PEMs were identified that covered 7 out of 40 investigated food groups (strawberry, cabbages, beetroot, walnut, citrus, green beans and chocolate). The PEMs reflected foods with a distinct composition rather than foods eaten more frequently or in larger amounts. We found that 23 % of the PEMs found in a previous meal study were also valid in the present intervention study. The study demonstrates that it is possible to discover and validate PEMs for several foods and food classes in an intervention study with a mixed dietary background, despite the large variability in such a dataset. Final validation of PEMs for intake of foods should be performed by quantitative analysis.

Salinity Selection for a Low Salinity Water-Low Salinity Surfactant Process

A laboratory selection of salinity for a low salinity water-low salinity surfactant (LS-LSS) process is presented in this paper with systematical investigation on surfactant phase behavior, interfacial tension (IFT), and dynamic retention in porous media with IOS2024 and isoamyl alcohol (IAA) as surfactant system. The results show that 0.4 wt% IOS2024 with 1 wt% IAA can provide ultra-low IFT of 10^?3 mN/m at around 3000–4000 mg/L total dissolved solids, but at that salinity range the surfactant retention is very high. The search for an optimum surfactant formulation has to consider solution properties and retention in addition to the low IFT. The salinity for a LS-LSS process should thus not be focused on either optimal salinity or ultra-low IFT, but instead the best choice could be a compromise between the properties in question. The three-phase region, where ultra-low IFT are found, is also associated with high retention values. However, we show that as salinity is increased from a two-phase region with oil solubilized in a water continuous microemulsion, there is a region close to the three-phase boundary which has potential. This region does not give ultra-low, but fairly low (10^?2 mN/m in this case) interfacial tensions, and also significantly lower retention.      

Similarities and Differences of Low Salinity Polymer and Low Salinity LPS (Linked Polymer Solutions) for Enhanced Oil Recovery

Linked polymer solution (LPS) is nano-size particles made of hydrolyzed polyacrylamide (HPAM) cross-linked with aluminum citrate. The propagation of LPS has been compared to non-cross-linked polymers at low brine salinity condition. The possible differences in properties and potentials for oil recovery have been investigated using water-wet and intermediate-wet cores. The target oil for polymer flooding (PF) is assumed to be the portion of the reservoir that has been bypassed by water during waterflooding and not the residual oil saturation in flooded zones. Our recent studies have shown that a positive synergy can be obtained by combining low salinity and PF. It has been claimed in the literature that cross-linking polymer such as colloidal dispersion gels (colloidal dispersion gels (CDG), micron-size aggregates) or LPS (nano-size particles) would extend the application of polymers to also include change in residual oil saturation. The results of this study indicated higher pressure buildup when low salinity LPS was propagated through brine saturated cores compared to low salinity polymer solution. The pressure buildup was even stronger for high salinity LPS injection. In two phase flow experiments, both polymer and LPS under low salinity condition, showed approximately similar propagation and oil recovery potential when injected into water-wet and intermediate-wet cores.     

Multidimensional De Novo Design Reveals 5‐HT2B Receptor‐Selective Ligands

We report a multi‐objective de novo design study driven by synthetic tractability and aimed at the prioritization of computer‐generated 5‐HT_2B receptor ligands with accurately predicted target‐binding affinities. Relying on quantitative bioactivity models we designed and synthesized structurally novel, selective, nanomolar, and ligand‐efficient 5‐HT_2B modulators with sustained cell‐based effects. Our results suggest that seamless amalgamation of computational activity prediction and molecular design with microfluidics‐assisted synthesis enables the swift generation of small molecules with the desired polypharmacology.     

Elucidating the origin of diastereoselectivity in a self-replicating system: selfishness versus altruism

We have investigated a diastereoselective self‐replicating system based on a cycloaddition of a fulvene derivative and a maleimide using a two‐pronged approach of combining NMR spectroscopy with computational modelling. Two diastereomers are formed with identical rates in the absence of replication. When replication is enabled, one diastereomer takes over the resources as a “selfish” autocatalyst, while exploiting the competitor as a weak “altruist”, resulting in a diastereoselectivity of 16:1. We applied 1D and 2D NMR spectroscopic techniques supported by ab initio chemical shifts as well as ab initio molecular dynamics simulations to study the structure and dynamics of the underlying network. This powerful combination allowed us to decipher the energetic and structural rationale behind the observed behaviour, while static computational methods currently used in the field did not.     

Accredited dose measurements for validation of radiation sterilized products

The activities and services of the accredited Risø High Dose Reference Laboratory are described. The laboratory operates according to the European standard EN 45001 regarding Operation of Testing Laboratories, and it fulfills the requirements of being able to deliver traceable dose measurements for control of radiation sterilization. The accredited services include:

1. 1. Irradiation of dosimeters and test samples with cobalt-60 gamma rays.

2. 2. Irradiation of dosimeters and test samples with 10 MeV electrons.

3. 3. Issue of and measurement with calibrated dosimeters.

4. 4. Measurement of the dosimetric parameters of an irradiation facility.

5. 5. Measurement of absorbed dose distribution in irradiated products.

The paper describes these services and the procedures necessary for their execution.