Correction to: Semi-automation of process analytics reduces operator effect.

In the original publication, open access funding institution was incorrectly mentioned in the acknowledgement section.

Semi-automation of process analytics reduces operator effect.

The aim of this study was to semi-automate process analytics for the quantification of common impurities in downstream processing such as host cell DNA, host cell proteins and endotoxins using a commercial liquid handling station. By semi-automation, the work load to fully analyze the elution peak of a purification run was reduced by at least 2.41 h. The relative standard deviation of results among different operators over a time span of up to 6 months was at the best reduced by half, e.g. from 13.7 to 7.1% in dsDNA analysis. Automation did not improve the reproducibility of results produced by one operator but released time for data evaluation and interpretation or planning of experiments. Overall, semi-automation of process analytics reduced operator-specific influence on test results. Such robust and reproducible analytics is fundamental to establish process analytical technology and get downstream processing ready for Quality by Design approaches.

Cyclotrimerization of phenylacetylene catalyzed by a cobalt half-sandwich complex embedded in an engineered variant of transmembrane protein FhuA.

An (η5-cyclopentadienyl)cobalt(i) complex was covalently incorporated into an engineered variant of the transmembrane protein ferric hydroxamate uptake protein component: A, FhuA ΔCVFtev, using a thiol-ene reaction. A CD spectrum shows the structural integrity of the biohybrid catalyst. MALDI-TOF of the segment containing the anchoring site for the cobalt complex Cys545 confirmed successful conjugation. This biohybrid catalyst catalyzed the cyclotrimerization of phenylacetylene to give a mixture of regioisomeric 1,2,4- and 1,3,5-triphenylbenzene in aqueous medium.

Metatheases: artificial metalloproteins for olefin metathesis.

The incorporation of organometallic catalyst precursors in proteins results in so-called artificial metalloenzymes. The protein structure will control activity, selectivity and stability of the organometallic site in aqueous medium and allow non-natural reactions in biological settings. Grubbs-Hoveyda type ruthenium catalysts with an N-heterocyclic carbene (NHC) as ancillary ligand, known to be active in olefin metathesis, have recently been incorporated in various proteins. An overview of these artificial metalloproteins and their potential application in olefin metathesis is given.

Dynamics of water-alcohol mixtures: insights from nuclear magnetic resonance, broadband dielectric spectroscopy, and triplet solvation dynamics.

We combine (2)H nuclear magnetic resonance (NMR), broadband dielectric spectroscopy (BDS), and triplet solvation dynamics (TSD) to investigate molecular dynamics in glass-forming mixtures of water and propylene glycol in very broad time and temperature ranges. All methods yield consistent results for the α process of the studied mixtures, which hardly depends on the composition and shows Vogel-Fulcher temperature dependence as well as Cole-Davidson spectral shape. The good agreement between BDS and TDS data reveals that preferential solvation of dye molecules in microheterogeneous mixtures does not play an important role. Below the glass transition temperature T(g), NMR and BDS studies reveal that the ß process of the mixtures shows correlation times, which depend on the water concentration, but exhibit a common temperature dependence, obeying an Arrhenius law with an activation energy of E(a) = 0.54 eV, as previously reported for mixtures of water with various molecular species. Detailed comparison of NMR and BDS correlation functions for the ß process unravels that the former decay faster and more stretched than the latter. Moreover, the present NMR data imply that propylene glycol participates in the ß process and, hence, it is not a pure water process, and that the mechanism for molecular dynamics underlying the ß process differs in mixtures of water with small and large molecules.

An optical supernova associated with the X-ray flash XRF 060218.

Long-duration gamma-ray bursts (GRBs) are associated with type Ic supernovae that are more luminous than average and that eject material at very high velocities. Less-luminous supernovae were not hitherto known to be associated with GRBs, and therefore GRB-supernovae were thought to be rare events. Whether X-ray flashes--analogues of GRBs, but with lower luminosities and fewer gamma-rays--can also be associated with supernovae, and whether they are intrinsically 'weak' events or typical GRBs viewed off the axis of the burst, is unclear. Here we report the optical discovery and follow-up observations of the type Ic supernova SN 2006aj associated with X-ray flash XRF 060218. Supernova 2006aj is intrinsically less luminous than the GRB-supernovae, but more luminous than many supernovae not accompanied by a GRB. The ejecta velocities derived from our spectra are intermediate between these two groups, which is consistent with the weakness of both the GRB output and the supernova radio flux. Our data, combined with radio and X-ray observations, suggest that XRF 060218 is an intrinsically weak and soft event, rather than a classical GRB observed off-axis. This extends the GRB-supernova connection to X-ray flashes and fainter supernovae, implying a common origin. Events such as XRF 060218 are probably more numerous than GRB-supernovae.

2H NMR studies of glycerol dynamics in protein matrices.

We use (2)H NMR spectroscopy to investigate the rotational motion of glycerol molecules in matrices provided by the connective tissue proteins elastin and collagen. Analyzing spin-lattice relaxation, line-shape properties, and stimulated-echo decays, we determine the rates and geometries of the motion as a function of temperature and composition. It is found that embedding glycerol in an elastin matrix leads to a mild slowdown of glycerol reorientation at low temperatures and glycerol concentrations, while the effect vanishes at ambient temperatures or high solvent content. Furthermore, it is observed that the nonexponential character of the rotational correlation functions is much more prominent in the elastin matrix than in the bulk liquid. Results from spin-lattice relaxation and line shape measurements indicate that, in the mixed systems, the strong nonexponentiality is in large part due to the existence of distributions of correlation times, which are broader on the long-time flank and, hence, more symmetric than in the neat system. Stimulated-echo analysis of slow glycerol dynamics reveals that, when elastin is added, the mechanism for the reorientation crosses over from small-angle jump dynamics to large-angle jump dynamics and the geometry of the motion changes from isotropic to anisotropic. The results are discussed against the background of present and previous findings for glycerol and water dynamics in various protein matrices and compared with observations for other dynamically highly asymmetric mixtures so as to ascertain in which way the viscous freezing of a fast component in the matrix of a slow component differs from the glassy slowdown in neat supercooled liquids.

Large-area, uniform, high-spatial-frequency ripples generated on silicon using a nanojoule-femtosecond laser at high repetition rate.

Large-area high-spatial-frequency patterns (HSFLs) of λ/6 periodicity have been generated by a nanojoule-femtosecond laser scanning technique (80 MHz, 170 fs, 700-950 nm) at the silicon-air interface. The excellent large-area uniformity allowed reproducible and accurate measurements of the periodicity. Variation of experimental parameters as illumination geometry, and pulse energy and number showed no influence on the ripple spacing. A wavelength dependence was observed and compared to current models of HSFL formation. A particular second-harmonic model was found to match the results best but needs to take into account transient changes in the refractive index under laser exposure. A second-harmonic mechanism is further supported by direct spectroscopic observation.

Celiac and perigastric lymph node metastasis of prostate cancer diagnosed with endoscopic ultrasound-guided fine-needle aspiration.

Endoscopic ultrasound has been used to diagnose and stage gastrointestinal and nongastrointestinal tumours. To our knowledge, the present report describes the first case of celiac and perigastric lymph node metastasis of prostate cancer diagnosed with endoscopic ultrasound-guided fine-needle aspiration.

Lifetime and Performance Assessment of Commercial Electric Double-Layer Capacitors Based on Cover Layer Formation.

The lifetime and performance of energy storage systems are essential characteristics for a major success of clean energy innovations, especially regarding the automotive sector. In this area, electric double-layer capacitors represent the cutting edge of nonfaradaic, high power, and long lifetime energy storages. Usually, degradation is neglected while operating or it is assessed by referring to simple rules of thumb. To better address the aging effects, commercial specimens have been investigated in-depth. The works can be split into two parts: first, extensive accelerated aging for more than 3 years to statistically analyze the degradation trend and significantly improve the current rules. Second, cell opening and surface characterization of the electrodes to gain a profound understanding of the ongoing processes and to correlate aging mechanisms to the statistics of the first part. It is found that a prominent cover layer forms during degradation on the positive electrode scaling with lost capacitance. The used methods for in-depth characterization include microscopy, X-ray diffraction, and thermogravimetric analysis with subsequent mass spectrometry. The newly formed layer consists of poly(tetrafluoroethylene) (also known as Teflon) that is still passable by charge carriers, albeit with a longer time constant. Additionally, the negative electrode shows corrosion and loss of contact. The composition of the cover layer has not been known yet. Thus, materials and especially electrolyte development can benefit from the results.

Application of an artificial neural network to predict specific class I MHC binding peptide sequences.

Computational methods were used to predict the sequences of peptides that bind to the MHC class I molecule, K(b). The rules for predicting binding sequences, which are limited, are based on preferences for certain amino acids in certain positions of the peptide. It is apparent though, that binding can be influenced by the amino acids in all of the positions of the peptide. An artificial neural network (ANN) has the ability to simultaneously analyze the influence of all of the amino acids of the peptide and thus may improve binding predictions. ANNs were compared to statistically analyzed peptides for their abilities to predict the sequences of K(b) binding peptides. ANN systems were trained on a library of binding and nonbinding peptide sequences from a phage display library. Statistical and ANN methods identified strong binding peptides with preferred amino acids. ANNs detected more subtle binding preferences, enabling them to predict medium binding peptides. The ability to predict class I MHC molecule binding peptides is useful for immunolological therapies involving cytotoxic-T cells.

Relation between myocardial infarct location and stroke.

OBJECTIVES: We sought to compare the likelihood of stroke in patients with anterior versus nonanterior myocardial infarction. BACKGROUND: The association between anterior infarction and left ventricular thrombus has led to the assumption that embolization from thrombi is an important cause of stroke in patients with anterior infarction. We hypothesized that if anterior infarction is a cause of left ventricular thrombi, the number of strokes should be disproportionately higher in patients with anterior than nonanterior infarction. METHODS: We performed a retrospective analysis of 2,466 patients randomized from day 3 to day 15 after infarction as part of a multicenter placebo-controlled study of diltiazem to prevent cardiac death or myocardial infarction. Any acute focal cerebral disorder resulting in localizing findings characterized as a stroke or transient ischemic attack was considered an event. RESULTS: Of 91 events during a follow-up period of 12 to 52 months, 23 (3.2%) occurred in 724 patients with an anterior and 68 (3.9%) in 1,742 patients with a nonanterior myocardial infarction (relative risk 0.81; 95% confidence interval 0.51 to 1.30). Power analysis revealed that the negativity of the study was not the result of inadequate sample size. Life table analysis showed no difference in cumulative event rate (p = 0.42) according to site of infarction. Cox regression analysis showed that of 10 clinical covariates, only systolic blood pressure was predictive of stroke (p < 0.001). The use of warfarin did not contribute to the model. Finally, the addition of site of infarction (anterior vs. nonanterior) did not contribute significantly to the Cox model. CONCLUSIONS: Although there is a significant incidence of stroke after acute myocardial infarction, there is no relation between the occurrence of stroke and site of infarction. These data do not support the presumed causal relation between anterior myocardial infarction, thrombus and stroke.

Sub-100 nm nanostructuring of silicon by ultrashort laser pulses.

Techniques based on laser scanning microscopes for nanoprocessing of periodic structures on silicon with ultra-short laser pulses have been developed. Ripples of 800-900 nm spacing were obtained after laser irradiation at a wavelength of 1040 nm, a repetition rate of 10 kHz and a fluence of 2 J/cm2 in air. Smaller features of 70-100nm spacing were achieved in oil at a wavelength of 800 nm, a repetition rate of 90 MHz and a fluence of 200-300 mJ/cm2 by using a high numerical focusing objective.

PAF antagonist ginkgolide B reduces postischemic neuronal damage in rat brain hippocampus.

We investigated the effect of the known antagonist of platelet-activating factor (PAF), ginkgolide B, on postischemic neuronal damage in the rat. Neuronal necroses were evaluated in the hippocampus 7 days after a 10-min forebrain ischemia. Preischemic application of ginkgolide B (50 mg/kg p.o.) significantly reduced neuronal damage. It is suggested that the antagonism of PAF is responsible for this beneficial effect of ginkgolide B.

Effects of cerebroprotective agents on cerebral blood flow and on postischemic energy metabolism in the rat brain.

Male Wistar rats were subjected to forebrain ischemia of 10 min duration by clamping both common carotid arteries and simultaneously lowering systemic blood pressure to 40 mm Hg by exsanguination. Recovery was achieved by removing the arterial clamps and reinfusing the blood. Cortical levels of high-energy phosphates and glycolytic substrates were determined enzymatically. Naftidrofuryl (10 or 20 mg/kg i.p.) or ketamine (5 mg/kg i.v.) were applied 30 min prior to the induction of ischemia. S(-)-Emopamil (4 mg/kg) or nimodipine (50 micrograms/kg) were administered by intravenous infusion over 30 min. Nimodipine and emopamil increased the blood glucose level and lowered preischemic blood pressure. Under control conditions, a tendency toward a higher cortical glucose level was observed in treated brains. Brain energy stores were exhausted after ischemia in control and treated animals to the same degree. Lactate levels, however, were higher in emopamil-treated animals. This effect was attributed to the elevated preischemic glucose levels. During the early recovery period, the restoration of high-energy phosphates was accelerated by both calcium entry blockers. Nimodipine and emopamil increased the levels of glucose and glucose-6-phosphate in the early postischemic period. Naftidrofuryl (10 mg/kg) increased the level of creatine-phosphate and ATP after 2 min of recovery. Naftidrofuryl (20 mg/kg) exerted no effect on cerebral energy metabolism, but considerably reduced postischemic blood pressure (possibly thereby masking its ameliorative action). Ketamine accelerated the postischemic restoration of high-energy phosphates. In the conscious rat, local cerebral blood flow (LCBF) was determined with the 14C-iodoantipyrine technique following emopamil (20 mg/kg s.c.) or naftidrofuryl (10 mg/kg i.v.) application.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of the cerebroprotective efficacy of the competitive NMDA receptor antagonist CGP40116 in a rat model of focal cerebral ischemia: an in vivo magnetic resonance imaging study.

The cerebroprotective properties of the competitive NMDA antagonist D-(E)-2-amino-4-methyl-5-phosphono-3-pentenoic acid (CGP 40116) were evaluated in a rat model of focal cerebral ischemia. CGP 40116 (5-40 mg/kg i.v.) was injected immediately following permanent occlusion of the left middle cerebral artery (MCA). MK 801 (1 or 3 mg/kg i.v.), D-CPPene (20 mg/kg i.v.), and CGS 19755 (40 mg/kg i.v.) were used for comparison. Lesion volume was assessed using in vivo magnetic resonance imaging, which in initial experiments with parallel histological determinations proved to be an accurate method for the measurement of brain infarction and the determination of a cerebroprotective drug effect. CGP 40116 dose-dependently reduced the volume of cortical infarction, with an ED50 of 11 mg/kg i.v. and a maximal effect equivalent to a 62% reduction in cortical edema volume. Its cerebroprotective efficacy was thus comparable to that of MK 801. The rank order of potency for the NMDA antagonists was MK 801 > CGP 40116 approximately D-CPPene > CGS 19755. Neuroprotection by CGP 40116 was still apparent when treatment was started 30 min after MCA occlusion. It is concluded that CGP 40116 is an effective cerebroprotectant with potential clinical utility for amelioration of focal cerebral ischemic damage.

The competitive NMDA antagonist CGP 40116 permanently reduces brain damage after middle cerebral artery occlusion in rats.

In this study we evaluated the effect of the competitive N-methyl-D-aspartate (NMDA) antagonist D-(E)-4-(3-phosphonoprop-2-enyl)piperazine-2-carboxylic acid (CGP 40116) on both early (2 days) and late (28 days) ischemic brain damage in a rodent model of focal cerebral ischemia by means of magnetic resonance imaging (MRI) and conventional histology. Immediately after occlusion of the left middle cerebral artery (MCA), rats received either CGP 40116 (20 mg/kg i.p.) or isotonic saline. Two MRI scans were performed in each animal 2 and 28 days after MCA occlusion. After the second scan, rats were perfusion fixed for histological evaluation. The volume of lesioned brain tissue as determined by MRI or histology was calculated from the damaged area in single sections and the distance between them. CGP 40116 reduced acute infarct volume as measured by MRI 2 days after MCA occlusion by 44% (p < 0.05, analysis of variance). After 28 days the lesion detected by MRI was still significantly smaller in the drug-treated animals. This finding was confirmed by the histological analysis showing a 64% reduction in the volume of brain atrophy in the CGP 40116 group (p < 0.05, analysis of variance). There was a good correlation between the MRI data and the results of the histological evaluation (r = 0.9). Our results indicate that (a) the competitive NMDA antagonist CGP 40116 permanently protects brain tissue from the consequences of cerebral ischemia in a rat model for human stroke and (b) early and late pathological changes can be accurately measured by MRI.