The Future of Sol-Gel Science and Technology

This paper addresses the future prospects for sol-gel processing. It includes responses from nearly two dozen leading practitioners of the sol-gel art, who were kind enough to answer a questionnaire about the present state and future directions of the field. Overall, the prospects appear quite bright; but achievement of anything like the full potential of the method will require greatly increased interaction between sol-gel specialists and device technologists.     

Inside‐out Ultraviolet‐C Sterilization of Pseudomonas aeruginosa Biofilm In Vitro

Biofilms are difficult to eradicate due to a protective architecture and create major challenges in patient care by diminishing both host immune response and therapeutic approaches. This study investigated a new strategy for treating surface‐attached biofilms by delivering germicidal UV through a material surface in a process referred to as “inside‐out sterilization” (IOS). Mature Pseudomonas aeruginosa (ATCC^® 27853^?) biofilms were irradiated with up to 1400 mJ cm^?2 of germicidal UV from both ambient and IOS configurations. The lethal dose for the ambient exposure group was 461 mJ cm^?2 95% CI [292, 728] compared to the IOS treatment group of 247 mJ cm^?2 95% CI [187, 325], corresponding to 47% less UV dosage for the IOS group (P < 0.05). This study demonstrated that with IOS, a lower quantal dosage of UV energy is required to eradicate biofilm than with ambient exposure by leveraging the organizational structure of the biofilm.     

Sol-Gel Derived Bismuth Titanate Thin Films with c-Axis Orientation

Bismuth titanate (Bi₄Ti₃O₁₂), a member of the layered perovskite family, has a unique set of ferroelectric properties, which include a high remanent polarization, low coercive field, and high Curie temperature, that make it a possible candidate for data storage applications. For this investigation, bismuth titanate, or BiT, films were fabricated via sol-gel method to examine the effect of processing on phase development and orientation. Solutions were deposited onto platinized silicon, and then heat treated for one hour at temperatures ranging from 550°C to 700°C in 100% O₂. It was found that c-axis orientated BiT films could be formed at temperatures as low as 550°C by using bismuth oxide template layers, while films without bismuth oxide templating possessed a random orientation over the same temperature range.     

Thienopyrazine‐Based Low‐Bandgap Poly(heteroaryleneethynylene)s for Photovoltaic Devices

Summary: Low‐bandgap π‐conjugated polymers that consist of alkyl thiophene/alkoxy phenylene and 2,3‐diphenylthieno[3,4‐b]pyrazine units have been prepared in high yields by a Sonogashira polycondensation. The copolymers are characterized by NMR, IR, UV, GPC, and elemental analysis. Thin films of the polymers P1 , P2 , and P3 exhibit an optical bandgap of ≈1.57–1.60 eV. Under simulated AM 1.5 conditions P2/PCBM devices on polyester foil provide a short circuit current of I_SC = 10.72 mA · cm⁻², an open circuit voltage of V_oc = 0.67 V, and a power conversion efficiency of 2.37%.

Schematic of the photovoltaic device made from the polymers synthesized here.     

The Structure of a Transient Complex of a Nonribosomal Peptide Synthetase and a Cytochrome P450 Monooxygenase

Studying the interplay between nonribosomal peptide synthetases (NRPS), a major source of secondary metabolites, and crucial external modifying enzymes is a challenging task since the interactions involved are often transient in nature. By applying a range of synthetic inhibitor‐type compounds, a stabilized complex appropriate for structural analysis was generated for such a tailoring enzyme and an NRPS domain. The complex studied comprises an NRPS peptidyl carrier protein (PCP) domain bound to the Cytochrome P450 enzyme that is crucial for the provision of β‐hydroxylated amino acid precursors in the biosynthesis of the cyclic depsipeptide skyllamycin. The structure reveals that complex formation is governed by hydrophobic interactions, the presence of which can be controlled through minor alterations in PCP structure that enable selectivity amongst multiple highly similar PCP domains.     

Evaluation of a potential epigenetic biomarker by quantitative methyl-single nucleotide polymorphism analysis

Tumorigenesis is characterized by alterations of methylation profiles including loss and gain of 5-methylcytosine. Recently, we identified a single CpG, which seemed to be consistently hypomethylated in pilocytic astrocytomas but not in other gliomas. To evaluate its applicability as a biomarker, we examined its methylation status in a large panel of gliomas (n = 97). Methylation-dependent DNA sequence variation may be considered a kind of single nucleotide polymorphism (methylSNP). MethylSNPs can be easily converted into common SNPs of the C/T type by sodium bisulfite treatment of the DNA and afterwards subjected to conventional SNP typing. We adapted SnaPshot trade mark and Pyrosequencing trade mark to determine the methylation of our test CpG in a quantitative manner. The adapted methods, called SNaPmeth and PyroMeth, respectively, gave nearly identical results, however data obtained with PyroMeth showed less scattering. Furthermore, the integrated software for allele frequency determination from Pyrosequencing could be used directly for data analysis while SnaPmeth data had to be exported and processed manually. Although data did not confirm our previous result of a preferential hypomethylation of the tested CpG in pilocytic astrocytomas, we consider quantitative methylSNP analysis by SNaPmeth or PyroMeth a favorable alternative to existing high-throughput methylation assays. It combines single CpG analysis with accurate quantitation and is amenable to high throughput.     

Solid-state assisted synthesis of oligobenzoates

The solid-state assisted synthesis opens an easy access to oligobenzoates end-capped with gallic acid, protocatechuic acid or 4-hydroxybenzoic acid etherified with long flexible chains – which are important precursors for liquid crystalline materials. The latter may consist of aliphatic, oligoethyleneoxy and semiperfluorinated chains. The rapid preparation of oligoesters with different peripheries is demonstrated.     

Reconstruction of inclusions in an elastic body

We consider the reconstruction of elastic inclusions embedded inside of a planar region, bounded or unbounded, with isotropic inhomogeneous elastic parameters by measuring displacements and tractions at the boundary. We probe the medium with complex geometrical optics solutions having polynomial-type phase functions. Using these solutions we develop an algorithm to reconstruct the exact shape of a large class of inclusions including star-shaped domains and we implement numerically this algorithm for some examples.     

A new Apparatus for Long-term Petrophysical Investigations on Geothermal Reservoir Rocks at Simulated In-situ Conditions

We present a new apparatus capable of maintaining in-situ conditions pertinent to deep geothermal reservoirs over periods of months while in the same time allowing a variety of continuous petrophysical investigations. Two identical devices have been set up at the GFZ-Potsdam. Lithostatic overburden- and hydrostatic pore pressures of up to 100 and 50 MPa, respectively can be simulated. In addition in-situ temperature requirements of up to 200°C can be met. The use of corrosion resistant parts throughout the pore pressure system allows investigations with highly saline formation fluids. Rock permeability, electrical conductivity as well as compressional- and shear-wave velocities can be measured simultaneously and the pore fluid can be sampled under pressure for further chemical analysis. Scientifically, the usage of the device focuses on risk potentials in exploration and exploitation of deep geothermal reservoirs. Particularly, the investigations address possible effects of fluid-rock interactions on the transport properties of a reservoir host rock.