Asymmetric Bioreduction of CC Bonds using Enoate Reductases OPR1, OPR3 and YqjM: Enzyme‐Based Stereocontrol

Three cloned enoate reductases from the “old yellow enzyme” family of flavoproteins were investigated in the asymmetric bioreduction of activated alkenes. 12‐Oxophytodienoate reductase isoenzymes OPR1 and OPR3 from Lycopersicon esculentum (tomato), and YqjM from Bacillus subtilis displayed a remarkably broad substrate spectrum by reducing α,β‐unsaturated aldehydes, ketones, maleimides and nitroalkenes. The reaction proceeded with absolute chemoselectivity – only the conjugated CC bond was reduced, while isolated olefins and carbonyl groups remained intact – with excellent stereoselectivities (ees up to >99%). Upon reduction of a nitroalkene, the stereochemical outcome could be determined via choice of the appropriate enzyme (OPR1 versus OPR3 or YqjM), which furnished the corresponding enantiomeric nitroalkanes in excellent ee. Molecular modelling suggests that this “enzyme‐based stereocontrol” is caused by subtle differences within the active site geometries.     

Cognition-enhanced assembly sequence planning for ergonomic and productive human–robot collaboration in self-optimizing assembly cells

Self-optimizing robotized assembly systems are able to compensate the restricted operation purpose of traditional robotized automation, in order to adapt dynamically to changed production conditions. As the human operator is directly involved in the assembly process, the interaction between the human and the robot has to be designed carefully to avoid exposing the human to excessive physical and cognitive strain. For controlling a robotized assembly cell, a Cognitive Control Unit (CCU) was developed that uses the cognitive software Soar and human-like assembly strategies to achieve a transparent and understandable assembly process. To minimize the cognitive and ergonomic risks during assembly, the CCU was extended by a graph-based assembly sequence planner (GASP). The GASP is able to find the optimal assembly sequence by using a complete assembly graph of the final product as well as generic production rules for assessing the ergonomic conditions of the individual assembly steps. The presented simulation study validates the functionality of the GASP with respect to the number of workflow switches between the human and the robot, the number of switches between the robotic tools, as well as the number of assembly group switches required to collaboratively assemble a model of a Stromberg carburetor. The results show a significant reduction of all three measures. The number of parts and the type of assessment of the assembly steps have a significant impact here.     

短小精悍——BenQ CP225投影机

BenQ的投影机在中国市场占有率一直都比较大,无论是家用还是商务领域, BenQ的投影技术的贡献都起着举足轻重的地位。市场目光敏锐且极具创新性的BenQ能紧紧抓住用户的需求,开发出适合不同阶层和场合的产品。在中低端投影机市场上,完善的功能和方便灵活的应用性越来越受到用户的重视,便携和环境的适应性无疑是人们重点考虑的因素之一。     

Unilateral internal carotid arterial occlusion: special considerations

Cases of patients with unilateral internal carotid arterial occlusion and contralateral internal carotid arterial stenosis are reviewed. Forty-two percent presented with a fixed neurological deficit. The deficit was referable to the side of occlusion in 92% and to the side of stenosis in 8%. Eleven percent had a neurological complication following carotid endarterectomy on the side of the stenotic lesion. The neurological complication was referable to the side of stenosis in 67% and to the side of occlusion in 33%. Patients have been followed for an average of 19 months and have not developed any additional TIA's or strokes in the followup period. There may be a role for an extracranial-intracranial bypass (ECIC) on the occluded side prior to an endarterectomy on the stenotic side if a poor collateral situation exists. An ECIC should be done in patients who remain symptomatic following carotid endarterectomy on the stenotic side. These data do not support doing ECIC in asymptomatic patients with unilateral carotid arterial occlusion.     

Evaluation of air acidity through optical sensors

Optical sensors developed from dye-doped coatings obtained through the sol-gel method were designed and produced to evaluate air acidity. Both laboratory calibration and field test measurements in several locales of downtown Cracow, Poland, were undertaken with the aim of assessing the sensors' behavior. As a first approach, SO2 was considered as the main gaseous pollutant with acid properties capable of sensitizing the sensors under humid conditions. A relationship between the SO2 concentration measured by conventional automatic air pollution monitoring stations and the optical response of the sensors was established. To correlate such a relationship with the air acidity, a simple calculation, which also takes into account relative humidity, temperature, and atmospheric pressure, was done. Following this calculation, the sensors' detection threshold for pH was found to be 0.05, approximately. The sensors can be a very useful analytical tool to alert against acid rain risks in preventive conservation of historical materials, among other applications.     

Automatischer Nullabgleich

Firmen&;ProdukteHF-Messungen

Automatischer Nullabgleich     

Group delay and chromatic dispersion of thin-film-based,narrow bandpass filters used in dense wavelength-division-multiplexed systems

Theoretical analysis is made for thin-film-based, 200- and 100-GHz narrow bandpass filters with respect to the intensity response as well as to the chromatic dispersion. The results indicate that the narrower the passband, the higher the chromatic dispersion. The maximum chromatic dispersion appears at the edges of the 0.5-dB passband, owing to the fast change of the group delay in the region. The deviation of chromatic dispersion induced by manufacturing error is simulated. Effective-medium approximation layers are added to simulate the contribution of surface roughness and the mixture interfaces to the passband ripple as well as the chromatic dispersion. The simulations are compared with the experimental results. The measured chromatic dispersion matches the general trend of the theoretical calculation. The imperfect surface and layer mismatch induce additional ripples across the 0.5-dB passband. The maximum chromatic dispersion within a 0.5-dB passband is 20.7 and 54.9 ps/nm for 200- and 100-GHZ narrow bandpass filters, respectively.