256×256 focal plane array midwavelength infrared camera based on InAs/GaSb short-period superlattices

An infrared camera based on a 256×256 focal plane array (FPA) for the second atmospheric window (3–5 μm) has been realized for the first time with InAs/GaSb short period superlattices (SLs). The SL detector structure with a broken gap type-II band alignment was grown by molecular beam epitaxy on GaSb substrates. Effective bandgap and strain in the superlattice were adjusted by varying the thickness of the InAs and GaSb layers and the controlled formation of InSb-like bonds at the interfaces. The FPAs were processed in a full wafer process using optical lithography, chemical-assisted ion beam etching, and conventional metallization technology. The FPAs were flip-chip bonded using indium solder bumps with a read-out integrated circuit and mounted into an integrated detector cooler assembly. The FPAs with a cut-off wavelength of 5.4 μm exhibit quantum efficiencies of 30% and detectivity values exceeding 10¹³ Jones at T=77 K. A noise equivalent temperature difference (NETD) of 11.1 mK was measured for an integration time of 5 ms using f/2 optics. The NETD scales inversely proportional to the square root of the integration time between 5 ms and 1 ms, revealing background limited performance. Excellent thermal images with low NETD values and a very good modulation transfer function demonstrate the high potential of this material system for the fabrication of future thermal imaging systems.     

Asparaginyl Ligases: New Enzymes for the Protein Engineer's Toolbox

Enzyme-catalysed site-specific protein modifications enable the precision manufacture of conjugates for the study of protein function and/or for therapeutic or diagnostic applications. Asparaginyl ligases are a class of highly efficient transpeptidases with the capacity to modify proteins bearing only a tripeptide recognition motif. Herein, we review the types of protein modification that are accessible using these enzymes, including N- and C-terminal protein labelling, head-to-tail cyclisation, and protein-protein conjugation. We describe the progress that has been made to engineer highly efficient ligases as well as efforts to chemically manipulate the enzyme reaction to favour product formation. These enzymes are powerful additions to the protein engineer‘s toolbox.     

Some performance comparisons for a fluid dynamics code

The 3D transient motion of a buoyancy-driven perfect gas in an enclosure is computed by a FORTRAN program (BF3D). A combustion model for eventual inclusion in this program is under development. BF3D changes slowly, has a long lifetime, and is run fairly infrequently. Typical runs have large storage and CPU requirements. BF3D runs on large supercomputers but the newer mini-supercomputers appear to be suitable also and may be advantageous for ease of access and usage. Programming workstations are convenient for development. Comparisons of BF3D on selected supercomputers, mini-supercomputers, scientific workstations and conventional mainframes are presented for the purpose of making partial benchmark data available to the computing public.     

CASA: A knowledge-based tool for management consultants

The objective of strategic management consultant work is a comprehensive evaluation of the ethical values of the management, the capabilities of the employees and the performance of the administrative systems in order to develop a well-suited corporate strategy. In order to fulfill all these requirements the management consultants have to take into consideration several hundred data. The human information processing capacity allows in such situations only the intuitive and condensed assessment of the strategic corporate status quo. The knowledge-based system CASA (Computer Aided Strategy Audit) assists the management consultant during the process of enterprise segmentation in order to create strategic business units, the analysis of the corporate culture, the assessment of market and competition, and the strategic cost situation. The system is used now since the CeBIT fair 1989, and includes: 5-MB code and help texts, 2000 rules in 44 knowledge bases and 200 pages of automatically generated reports and up to 100 business charts. The use of CASA reduces the costs for the management consultancy to 30% of the original costs, i.e., from $75,000 to $25,000 for a strategy development project.     

Absolute energy measurement of heavy ion beams using a resonant time-of-flight system

A resonant time-of-flight measurement system has been put into operation at the ATLAS facility for the determination of the energy of heavy ion beams. The system provides continuous, nondestructive monitoring of the beam energy. The system provides relative energy determination with a precision of . Absolute energy is determined to an accuracy of 10⁻³. A variety of beam tests have been performed to study the properties of the system.     

Characterization of CYP154F1 from Thermobifida fusca YX and Extension of Its Substrate Spectrum by Site‐Directed Mutagenesis

Previous studies on cytochrome P450 monooxygenases (CYP) from family 154 reported their substrate promiscuity and high activity. Hence, herein, the uncharacterized family member CYP154F1 is described. Screening of more than 100 organic compounds revealed that CYP154F1 preferably accepts small linear molecules with a carbon chain length of 8–10 atoms. In contrast to thoroughly characterized CYP154E1, CYP154F1 has a much narrower substrate spectrum and lower activity. A structural alignment of homology models of CYP154F1 and CYP154E1 revealed few differences in the active sites of both family members. By gradual mutagenesis of the CYP154F1 active site towards those of CYP154E1, a key residue accounting for the different activities of both enzymes was identified at position 234. Substitution of T234 for large hydrophobic amino acids led to up to tenfold higher conversion rates of small substrates, such as geraniol. Replacement of T234 by small hydrophobic amino acids, valine or alanine, resulted in mutants with extended substrate spectra. These mutants are able to convert some of the larger substrates of CYP154E1, such as (E)‐stilbene and (+)‐nootkatone.     

3D Printing for Chemical Process Laboratories I: Materials and Connection Principles

The fabrication of milliliter‐scale test structures for chemical process laboratories with a low‐cost 3D printer operating according to the principle of fused filament fabrication is evaluated. Different polymers such as polypropylene and poly(vinylidene fluoride) were used and fabrication guidelines are provided. Furthermore, reversible and irreversible concepts for connecting 3D‐printed parts to peripherals or to other additively manufactured parts are described. After fabrication, the structures were tested for gas tightness, which was limited without subsequent finishing due to the layer‐wise fabrication process. However, gas tightness up to 600 kPa was attained by using tools like sealing tape. Finally, the developed concepts were extended to permit the insertion of thermoelements or other metallic probes.