Silk for Drug Delivery Applications: Opportunities and Challenges

Silk fibers have been used in textiles for more than 5,000 years and as a suturing material for many centuries. The recent development of new applications for silks include drug delivery. An overview of this new field is provided, summarizing the development of emerging drug delivery applications which include silk-based nanomedicines and transdermal delivery systems We also highlight some of the challenges in developing silk-based drug delivery systems.     

Wien2wannier: From linearized augmented plane waves to maximally localized Wannier functions

We present an implementation of an interface between the full-potential linearized augmented plane wave package Wien2k and the wannier90 code for the construction of maximally localized Wannier functions. The FORTRAN code and a documentation is made available and results are discussed for SrVO₃, Sr₂IrO₄ (including spin-orbit coupling), LaFeAsO, and FeSb₂.     

Self-Consistent Quantum Mechanical Monte Carlo MOSFET Device Simulation

We have developed a self-consistent quantum mechanical Monte Carlo device simulator that takes electron transport in quantized states into consideration. Two-dimensional quantized states in MOSFET channels are constructed from one-dimensional solutions of the Schrödinger equation at different positions along the channel, and the Schrödinger and Poisson equations are solved self-consistently in terms of electron concentration and electrostatic potential distribution. The channel electron concentration, velocity and drain currents are calculated with the one particle Monte Carlo approach incorporating the intra-valley acoustic phonon and inter-valley phonon scattering mechanisms. This simulator was applied to a 70 nm n-MOSFET transistor, and we found that current mostly flows through the lowest subband and transport is quasi-ballistic near the source junction. To quantitatively estimate the performance of advanced devices, we have developed an inversion carrier transport simulator based on a full-band model. Our simulation method enables us to evaluate device characteristics and analyze the transport properties of ultra-small MOSFETs.     

Visualization of immune cell infiltration in experimental viral myocarditis by 19F MRI in vivo

Objective

This paper introduces a new approach permitting for the first time a specific, non-invasive diagnosis of myocarditis by visualizing the infiltration of immune cells into the myocardium.

Materials and methods

The feasibility of this approach is shown in a murine model of viral myocarditis. Our study uses biochemically inert perfluorocarbons (PFCs) known to be taken up by circulating monocytes/macrophages after intravenous injection.

Results

In vivo ¹⁹F MRI at 9.4 T demonstrated that PFC-loaded immune cells infiltrate into inflamed myocardial areas. Because of the lack of any fluorine background in the body, detected ¹⁹F signals of PFCs are highly specific as confirmed ex vivo by flow cytometry and histology.

Conclusion

Since PFCs are a family of compounds previously used clinically as blood substitutes, the technique described in our paper holds the potential as a new imaging modality for the diagnosis of myocarditis in man.     

Potential influence of Gadolinium contrast on image segmentation in MR-based attenuation correction with Dixon sequences in whole-body 18F-FDG PET/MR

Objective

To evaluate the influence of Gadolinium contrast agent on image segmentation in magnetic resonance (MR)-based attenuation correction (AC) with four-segment dual-echo time Dixon-sequences in whole-body [18F]-fluorodeoxyglucose positron emission tomography (PET)/MR imaging, and to analyze the consecutive effect on standardized uptake value (SUV).

Materials and methods

Hybrid imaging with an integrated PET/MR system was performed in 30 oncological patients. AC was based on MR imaging with a Dixon sequence with subsequent automated image segmentation. AC maps (µmaps) were acquired and reconstructed prior to (µmap_?gd) and after (µmap_+gd) Gd-contrast agent application. For quantification purposes, the SUV of organs and tumors based on both µmaps were compared.

Results

Tissue classification based on µmap_?gd was correct in 29/30 patients; based on µmap_+gd, the brain was falsely classified as fat in 12/30 patients with significant underestimation of SUV. In all cancerous lesions, tissue segmentation was correct. All concordant µmaps_?gd/+gd resulted in no significant difference in SUV.

Conclusion

In PET/MR, Gd-contrast agent potentially influences fat/water separation in Dixon-sequences of the head with above-average false tissue segmentation and an associated underestimation of SUV. Thus, MR-based AC should be acquired prior to Gd-contrast agent application. Additionally, integrating the MR-based AC maps into the reading-routine in PET/MR is recommended to avoid interpretation errors in cases where tissue segmentation fails.

     

Microfluidic behavior in melt-spun hollow and liquid core fibers

The development of thermoplastic fibers containing a liquid core is described. Internal morphology analysis confirms that the liquid-containing core is composed of a continuous cylindrical microchannel of constant diameter. Microfluidic experiments on both liquid core and reference hollow fibers were conducted by pumping distilled water through several filaments simultaneously. The observed fluid motions are satisfactorily described by the Hagen-Poiseuille law, indicating that the hollow and liquid core fibers have internal diameters of 31.6 and 14.8 µm, respectively. Flushing the liquid core fibers with a surfactant solution efficiently removes the saturated ester initially used during the melt spinning of the fiber.     

Formation Mechanism of Alkyl Nitrites,Valuable Intermediates in C1-Upgrading Chemistry and Oxidation Processes

In this contribution we use computational tools to investigate the reaction of alcohol substrates with reactive nitrogen oxide species such as N₂O₃ and N₂O₄, leading to the formation of alkyl nitrites. These nitrites are interesting intermediates which can be processed to various valuable chemicals such as ketones/aldehydes and dimethyl oxalate while regenerating NO _x . As such, NO _x is used as an oxidation mediator, converting alcohol substrates to more reactive nitrites which can be selectively converted to more desired compounds, closing a catalytic cycle in NO _x species.