Overcharging effect in electrospray ionization mass spectra of daunomycin-tuftsin bioconjugates

Peptide-based small molecule drug conjugates for targeted tumor therapy are currently in the focus of intensive research. Anthracyclines, like daunomycin, are commonly used anticancer drug molecules and are also often applied in peptide-drug conjugates. However, lability of the O-glycosidic bond during electrospray ionization mass spectrometric analysis hinders the analytical characterization of the constructs. “Overprotonation” can occur if daunomycin is linked to positively charged peptide carriers, like tuftsin derivatives. In these molecules, the high number of positive charges enhances the in-source fragmentation significantly, leading to complex mass spectra composed of mainly fragment ions. Therefore, we investigated different novel tuftsin-daunomycin conjugates to find an appropriate condition for mass spectrometric detection. Our results showed that shifting the charge states to lower charges helped to keep ions intact. In this way, a clear spectrum could be obtained containing intact protonated molecules only. Shifting of the protonation states to lower charges could be achieved with the use of appropriate neutral volatile buffers and with tuning the ion source parameters

Electron beam induced softening of fused silica

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Influence of densification on the indentation cracking behaviour

Nanoindentation is a versatile method to study the plastic deformation and cracking behavior of glasses on various length scale. For fused silica, plastic deformation occurs by volume conservative shear flow and inelastic densification. The Drucker-Prager-Cap (DPC) plasticity finite element analysis approach was used to describe the yield surface of fused silica by an ellipsis. This approach was extended by the implementation of a sigmoidal hardening behavior to take densification saturation into account. Cohesive Zone (CZ) FEM was used to model indentation cracking along median/radial axis. By using Raman spectroscopic mapping of indents and literature data on high pressure densification, the behavior of the finite element analysis approach to describe the densification profiles of indents is determined. Further the sensitivity of estimating densification from shifts in the Raman signal was investigated for different indent sizes. The results show that the precision of the densification estimate increases with indentation size and a rule of thumb for an appropriate experimental set-up is proposed. The extended Drucker-Prager-Cap approach in FEA delivers an accurate description of the densification field of a pyramidal indentation (i.e. Berkovich or Vickers) of silica glass and reproduces experimental data remarkably better than the conventional model. In CZ-FEM densification inhibits the crack extension by a factor of 15 % compared to the case of pure shear flow. This factor however is significant smaller than improvements in fracture behavior, which are often attributed to densification found in literature. For pillar splitting densification plays a negligible role

3D printed microchannels for sub-nL NMR spectroscopy

Nuclear magnetic resonance (NMR) experiments on subnanoliter (sub-nL) volumes are hindered by the limited sensitivity of the detector and the difficulties in positioning and holding such small samples in proximity of the detector. In this work, we report on NMR experiments on liquid and biological entities immersed in liquids having volumes down to 100 pL. These measurements are enabled by the fabrication of high spatial resolution 3D printed microfluidic structures, specifically conceived to guide and confine sub-nL samples in the sub-nL most sensitive volume of a single-chip integrated NMR probe. The microfluidic structures are fabricated using a two-photon polymerization 3D printing technique having a resolution better than 1 \u3bcm3. The high spatial resolution 3D printing approach adopted here allows to rapidly fabricate complex microfluidic structures tailored to position, hold, and feed biological samples, with a design that maximizes the NMR signals amplitude and minimizes the static magnetic field inhomogeneities. The layer separating the sample from the microcoil, crucial to exploit the volume of maximum sensitivity of the detector, has a thickness of 10 \u3bcm. To demonstrate the potential of this approach, we report NMR experiments on sub-nL intact biological entities in liquid media, specifically ova of the tardigrade Richtersius coronifer and sections of Caenorhabditis elegans nematodes. We show a sensitivity of 2.5x1013spins/ Hz1/2on1H nuclei at 7 T, sufficient to detect 6 pmol of1H nuclei of endogenous compounds in active volumes down to 100 pL and in a measurement time of 3 hours. Spectral resolutions of 0.01 ppm in liquid samples and of 0.1 ppm in the investigated biological entities are also demonstrated. The obtained results may indicate a route for NMR studies at the single unit level of important biological entities having sub-nL volumes, such as living microscopic organisms and eggs of several mammalians, humans included

Greenhouse Gas Emissions Modeling: A Tool for Federal Facility Decommissioning

The Federal Aviation Administration (FAA) facility inventory is constantly changing as newer systems supplant older infrastructure in response to technological advances. Transformational change embodied by the FAA’s Next Generation Air Transportation System (NextGen) will affect the replacement of thousands of ground-based air traffic control systems with satellite-based systems by 2025. NextGen alone will drive a massive facility decommissioning effort with the potential for major environmental impacts from demolition and disposal activities, including emissions of greenhouse gases (GHGs), criteria pollutants, and air toxics, erosion, runoff, noise, generation of solid waste, and the migration of contamination associated with historic releases of hazardous waste, fuel constituents, and hazardous building materials. The FAA and other federal agencies need effective environmental impact assessment tools to design mitigation strategies and ensure compliance with regulatory and policy drivers, including Executive Order (EO) 13514 Federal Leadership in Environmental, Energy, and Economic Performance, which establishes integrated strategies towards sustainability and greenhouse gas emissions reductions in the Federal Government. In this study we develop a model to facilitate the quantitative analysis of comprehensive GHG emissions inventories from demolition debris reuse, recycling, and disposal activities that accounts for scope 1, scope 2, and scope 3 emissions as defined by EO 13514. The results of the model are used to inform a trade-off analysis that compares the relative impacts of debris management alternatives. Data from the decommissioning of an air traffic control tower and an air route surveillance radar facility are used as case studies to refine and validate the model, which could be used as a tool to guide future decommissioning efforts at Federal facilities and to provide input to FAA’s agency-wide GHG emissions inventory