Mass spectrometric identification of cyclic polysulfides in sediment of the Eastern Gulf of Finland. I

Structures of six cyclic polysulfides, previously unknown as organic environmental pollutants, were analyzed from a sediment sample from the Eastern Gulf of Finland. The determinations were done by gas chromatography connected to mass spectrometry. High resolution (HRMS) measurements of the isotopic composition of four compounds could be done to confirm their molecular formulae. Total low resolution (LRMS) spectra were used to elucidate structures of all six compounds by thermochemical approach, application of fragmentation rules and by ICLU simulation of the spectra. The compounds were deduced to be (in the order of GC- retention) 1,2,4-trithiacycloheptane, tetrathiacyclopentane, 1,2,4,5-tetrathia-cyclohexane, 1,2,3,4- tetrathiacycloheptane, 1,2,3,4-tetrathiacyclohexane and 1,2,4,6-tetrathiacyclooctane.     

Atypical perceptual narrowing in prematurely born infants is associated with compromised language acquisition at 2 years of age

Background

Protein aggregation plays important roles in several neurodegenerative disorders. For instance, insoluble aggregates of phosphorylated tau and of Aβ peptides are cornerstones in the pathology of Alzheimer's disease. Soluble protein aggregates are therefore potential diagnostic and prognostic biomarkers for their cognate disorders. Detection of the aggregated species requires sensitive tools that efficiently discriminate them from monomers of the same proteins. Here we have established a proximity ligation assay (PLA) for specific and sensitive detection of Aβ protofibrils via simultaneous recognition of three identical determinants present in the aggregates. PLA is a versatile technology in which the requirement for multiple target recognitions is combined with the ability to translate signals from detected target molecules to amplifiable DNA strands, providing very high specificity and sensitivity.

Results

For specific detection of Aβ protofibrils we have used a monoclonal antibody, mAb158, selective for Aβ protofibrils in a modified PLA, where the same monoclonal antibody was used for the three classes of affinity reagents required in the assay. These reagents were used for detection of soluble Aβ aggregates in solid-phase reactions, allowing detection of just 0.1 pg/ml Aβ protofibrils, and with a dynamic range greater than six orders of magnitude. Compared to a sandwich ELISA setup of the same antibody the PLA increases the sensitivity of the Aβ protofibril detection by up to 25-fold. The assay was used to measure soluble Aβ aggregates in brain homogenates from mice transgenic for a human allele predisposing to Aβ aggregation.

Conclusions

The proximity ligation assay is a versatile analytical technology for proteins, which can provide highly sensitive and specific detection of Aβ aggregates - and by implication other protein aggregates of relevance in Alzheimer's disease and other neurodegenerative disorders.     

Saccharide‐Modified Nanodiamond Conjugates for the Efficient Detection and Removal of Pathogenic Bacteria

The detection and removal of bacteria, such as E. coli in aqueous environments by using safe and readily available means is of high importance. Here we report on the synthesis of nanodiamonds (ND) covalently modified with specific carbohydrates (glyco–ND) for the precipitation of type 1 fimbriated uropathogenic E. coli in solution by mechanically stable agglutination. The surface of the diamond nanoparticles was modified by using a Diels–Alder reaction followed by the covalent grafting of the respective glycosides. The resulting glyco–ND samples are fully dispersible in aqueous media and show a surface loading of typically 0.1 mmol g^?1. To probe the adhesive properties of various ND samples we have developed a new sandwich assay employing layers of two bacterial strains in an array format. Agglutination experiments in solution were used to distinguish unspecific interactions of glyco–ND with bacteria from specific ones. Two types of precipitates in solution were observed and characterized in detail by light and electron microscopy. Only by specific interactions mechanically stable agglutinates were formed. Bacteria could be removed from water by filtration of these stable agglutinates through 10 μm pore‐size filters and the ND conjugate could eventually be recovered by addition of the appropriate carbohydrate. The application of glycosylated ND allows versatile and facile detection of bacteria and their efficient removal by using an environmentally and biomedically benign material.     

Total Synthesis of Anti-MRSA Active Diorcinols and Analogues

Diorcinols and related prenylated diaryl ethers were reported to exhibit activity against methicillin-resistant clinical isolates of Staphylococcus aureus (MRSA). Within these lines, we report the first total synthesis of diorcinol D, I, J, the proposed structure of verticilatin and recently isolated antibacterial diaryl ether by using an efficient and highly divergent synthetic strategy. These total syntheses furnish the diaryl ethers in only five to seven steps employing a Pd-catalyzed diaryl ether coupling as the key step. The total synthesis led to the structural revision of the natural product verticilatin, which has been isolated from a plant pathogenic fungus. Furthermore, these structures were tested in order to determine their antibacterial activities against different MRSA strains as well as further Gram-positive and -negative bacteria.     

Influence of Perfluorinated End Groups on the SFRD of [Pt(cod)Me(CnF2n+1)] onto Porous Al2O3 in CO2 under Reductive Conditions

The optimized synthesis of a range of cyclooctadiene‐stabilized Pt complexes that contained different perfluoro‐alkane chains, [Pt(cod)Me(C_nF_2n+1)], is presented. These metal–organic compounds were employed in the so‐called supercritical fluid reactive deposition (SFRD) in CO₂ under reductive conditions to generate metallic nanoparticles on aluminum oxide as a porous support. Thus, Al₂O₃‐supported Pt nanoparticles with a narrow particle‐size distribution were obtained. At a reduction pressure of 15.5 MPa and a temperature of 353 K, particle diameters of d₅₀=2.3–2.8 nm were generated. Decreasing the pressure during the reduction reaction led to slightly larger particles whilst decreasing the amount of organometallic precursor in CO₂ yielded a decrease in the particle size from x₅₀=3.2 nm to 2.6 nm and a particle‐size distribution of 2.2 nm. Furthermore, substitution of the CH₃ end group by the C_nF_2n+1 end groups led to a significant drop in Pt loading of about 50 %. Within the series of perfluorinated end groups that were considered, the Pt complex that contained a branched perfluoro‐isopropyl group showed the most‐interesting results when compared to the control precursor, [Pt(cod)Me₂] ( 1 ).     

Proficiency test of pH,conductivity and dissolved oxygen concentration field measurements in river water

In 2013, Proftest SYKE organised the first proficiency test (PT) in Finland for field measurements of temperature, conductivity, dissolved oxygen concentration, oxygen saturation and pH value in river water. The aim was to pilot the organisation of an in situ proficiency test—particularly, how to select the test location—and how to assess the homogeneity and stability of the measurement site and the water to be tested. The focus was also to evaluate the suitability of the common field sensors used for water analysis, as well as the comparability of the results between the instruments under field conditions. The overall application of quality assurance procedures was also surveyed. This paper deals with the results, findings and recommendations for the measurement of pH, conductivity and dissolved oxygen concentration. In total, nine participants with 16 sensors took part in the proficiency test. For the evaluation of the performance of each participant, z scores were calculated allowing 3 % to 8 % deviation from the assigned value. The standard deviation of the participant’s results was lower than organiser expected, and 80 % of the results for pH, 79 % for conductivity and 69 % for dissolved oxygen concentration were regarded as satisfactory. According to the results, the most challenging measurement was for dissolved oxygen with a Clark cell-type measurement principle based on electrochemical reaction. All sensors tested in the PT were less than 5 years, old and they were calibrated according to the manufacturer’s instructions. None of the participants had estimated measurement uncertainty for their sensor measurements. In addition, internal and external quality assurance protocols were usually lacking.     

The role of hornification in the disintegration behaviour of TEMPO-oxidized bleached hardwood fibres in a high-shear homogenizer

The effect of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation on the structure of hornified fibres and their disintegration behaviour was studied by a method combining gradual disintegration of the fibre structure in an in-line homogenizer with a chromatographic separation technique. It was seen that hornification prior to TEMPO-mediated oxidation had a notable effect on the disintegration behaviour of bleached cellulose fibres in a high-shear homogenizer and on the properties of the resulting particles. Field-emission scanning electron microscopy imaging of the suspensions and viscosity and transmittance measurements revealed that never-dried oxidized fibres disintegrated into bunches of microfibrils and at higher charge densities into thinner and more individual microfibrils. These microfibrils were obtained from fibres through swelling and ballooning. The hornified fibres were mainly cut into shorter ones as the charge density increased. After reversing the hornification and allowing the fibres to swell further, however, microfibrils were also obtained from this source. The charge threshold for efficient microfibril production from never-dried fibres in the high-shear homogenizer used here was 0.7 mmol/g.     

Mechanical fabrication of high-strength and redispersible wood nanofibers from unbleached groundwood pulp

In the past, the direct production of lignin-containing nanofibers from wood materials has been very limited, and nanoscale fibers (nanocelluloses) have been mainly isolated from chemically delignified, bleached cellulose pulp. In this study, we have introduced a newly adapted, heat-intensified disc nanogrinding process for the enhanced nanofibrillation of wood nanofibers (WNF) with a high lignin content (27.4 wt%). The WNF produced this way have many unique and intriguing properties in their naturally occurring form, for example, being able to be dispersed in ethanol and having ethanol solution viscosities higher than water solution viscosities. When WNF nanopapers were formed with ethanol, the properties of the nanofibers were recoverable without a notable decrease in the viscosity or mechanical strength after redispersing them in water. The preservation of lignin in the WNF was noticed as an increase in the water contact angles (89°), the rapid removal of water in the fabrication of the nanopapers, and the enhanced strength of the nanopapers when subjected to high pressure and heat. The nanopapers fabricated from the WNF were mechanically stable, having an elastic modulus of 6.2 GPa, a maximum stress of 103.4 MPa, and a maximum strain of 3.5%. Throughout the study, characteristics of the WNF were compared to those of the delignified and bleached reference cellulose nanofibers. We envision that the exciting characteristics of the WNF and their lower cost of production compared to that of bleached cellulose nanofibers may offer new opportunities for nanocellulose and biocomposite research.