Konzeption und Entwicklung eines Condition Monitoring Systems mit Low Cost Sensoren zur Überwachung von Roboterschwingungen

Im Rahmen dieser Veröffentlichung wird ein Konzept zur Erfassung des Schwingungsverhaltens von Industrierobotern mit Hilfe von Low Cost Sensoren vorgestellt. Durch dieses sollen die dynamischen Eigenschaften des Industrieroboters im gesamten Arbeitsraum untersucht werden. Die Roboterstruktur wird dazu durch eine speziell konstruierte Unwuchtscheibe angeregt. Das Messsystem besteht aus einem Beschleunigungssensor, einem Arduino-Mikrocontroller und einem eigens entwickelten Mess- und Auswerteprogramm in der Softwareumgebung MATLAB®. Die Validierung des Konzeptes erfolgt jeweils mit Messreihen an einem Kragbalken sowie an einem Industrieroboter durch den Vergleich mit einem Referenzmesssystem der Firma Brüel & Kjaer. Durch das entwickelte Low Cost Condition Monitoring System lassen sich die Anregungsfrequenzen und –amplituden mit hinreichender Genauigkeit erfassen und Rückschlüsse auf das Schwingungsverhalten des Industrieroboters ziehen

Identification of a Negative Allosteric Site on Human α4β2 and α3β4 Neuronal Nicotinic Acetylcholine Receptors

Acetylcholine-based neurotransmission is regulated by cationic, ligand-gated ion channels called nicotinic acetylcholine receptors (nAChRs). These receptors have been linked to numerous neurological diseases and disorders such as Alzheimer's disease, Parkinson's disease, and nicotine addiction. Recently, a class of compounds has been discovered that antagonize nAChR function in an allosteric fashion. Models of human α4β2 and α3β4 nicotinic acetylcholine receptor (nAChR) extracellular domains have been developed to computationally explore the binding of these compounds, including the dynamics and free energy changes associated with ligand binding. Through a blind docking study to multiple receptor conformations, the models were used to determine a putative binding mode for the negative allosteric modulators. This mode, in close proximity to the agonist binding site, is presented in addition to a hypothetical mode of antagonism that involves obstruction of C loop closure. Molecular dynamics simulations and MM-PBSA free energy of binding calculations were used as computational validation of the predicted binding mode, while functional assays on wild-type and mutated receptors provided experimental support. Based on the proposed binding mode, two residues on the β2 subunit were independently mutated to the corresponding residues found on the β4 subunit. The T58K mutation resulted in an eight-fold decrease in the potency of KAB-18, a compound that exhibits preferential antagonism for human α4β2 over α3β4 nAChRs, while the F118L mutation resulted in a loss of inhibitory activity for KAB-18 at concentrations up to 100 µM. These results demonstrate the selectivity of KAB-18 for human α4β2 nAChRs and validate the methods used for identifying the nAChR modulator binding site. Exploitation of this site may lead to the development of more potent and subtype-selective nAChR antagonists which may be used in the treatment of a number of neurological diseases and disorders

"Surgery For Intractable Epilepsy, Loghman Hakim hospital, 1997-2003 "

Background: Regarding the complications of chronic intractable epilepsy, the presence of respectable lesions in many these patients that can be diagnosed with noninvasive sensitive techniques such as MRI and SPECT and the unrecognized significance of epilepsy surgery in our country, we have decided to review the management of medically intractable epilepsy in patients, who underwent epilepsy surgery in neurosurgery department of Loghman Hakim hospital between 1997-2003. Materials and Methods: In this study we retrospectively review 30 cases of medically intractable epilepsy that had underwent epilepsy surgery. All patients before surgery were investigated with brain MRI, brain SPECT, EEG and IQ test. Type of surgery was determined by MRI, SPECT and EEG findings. Pre - and postoperative seizure frequency and surgery complications studied. Seizure control was measured with Engel criteria. Results: Patients mean age was 22.4 years. Three cases (10%) were females that all underwent temporal mesial lobectomy. In 18 cases (60%) there were concordant brain lesion with seizure origin that 9 cases (30%) underwent mesial temporal lobectomy and remainder 9 cases (30%) underwent lesionectomy.other12 cases (40%) that have uncertain brain lesion but suffer from drop attack due to one or combination of atonic, tonic, tonic clonic, clonic, myoclonic, absence or clonic underwent anterior callosotomy. patients that underwent mesial temporal lobectomy, anterior callosotomy and lesionectomy were seizure-free in 77.7%, 58.3% and 55.5% of cases respectively. Conclusions: Provided to correct patient selection for epilepsy surgery we can manage intractable epilepsy properly. Regarding to the complication of intractable epilepsy, acceptable epilepsy surgery results and available sensitive noninvasive diagnostic techniques such as MRI in our country, epilepsy surgery should be considered seriously in our country and promoted

Comparison of the aggregation behavior of 15 polymeric and monomeric dipeptide surfactants in aqueous solution

The aggregation numbers of 15 dipeptide surfactants were estimated by use of fluorescence steady-state quenching techniques. Polymerization of the surfactants with γ radiation resulted in molecular micelles with a lower number of repeat units than the corresponding monomer aggregation numbers at the concentration of monomer used for polymerization in this study. In addition, the aggregation numbers of the monomers decreased with increasing size of the N-terminal R group of the dipeptide surfactants examined in this study. The aggregation behavior of the dipeptide surfactants was further investigated using proton NMR (1H NMR) spectroscopy. The proton resonances due to NH and Hα were measured above and below the critical micelle concentration of the surfactants. From the differences in proton chemical shifts of the monomeric dipeptide surfactants and aggregation numbers, a model for packing of the monomeric polar head is proposed

Context and Force Field Dependence of the Loss of Protein Backbone Entropy upon Folding Using Realistic Denatured and Native State Ensembles

The loss of conformational entropy is the largest unfavorable quantity affecting a protein’s stability. We calculate the reduction in the number of backbone conformations upon folding using the distribution of backbone dihedral angles (ϕ,ψ) obtained from an experimentally validated denatured state model, along with all-atom simulations for both the denatured and native states. The average loss of entropy per residue is <i>T</i>Δ<i>S</i>^BB_U–N = 0.7, 0.9, or 1.1 kcal·mol^–1 at <i>T</i> = 298 K, depending on the force field used, with a 0.6 kcal·mol^–1 dispersion across the sequence. The average equates to a decrease of a factor of 3–7 in the number of conformations available per residue (<i>f</i> = Ω_Denatured/Ω_Native) or to a total of <i>f</i>_tot = 3^<i>n</i>–7^<i>n</i> for an <i>n</i> residue protein. Our value is smaller than most previous estimates where <i>f</i> = 7–20, that is, our computed <i>T</i>Δ<i>S</i>^BB_U–N is smaller by 10–100 kcal mol^–1 for <i>n</i> = 100. The differences emerge from our use of realistic native and denatured state ensembles as well as from the inclusion of accurate local sequence preferences, neighbor effects, and correlated motions (vibrations), in contrast to some previous studies that invoke gross assumptions about the entropy in either or both states. We find that the loss of entropy primarily depends on the local environment and less on properties of the native state, with the exception of α-helical residues in some force fields