Humanoid Robotic System with and without Elasticity Elements Walking on an Immobile/Mobile Platform

This work is concerned with the modeling and analysis of a complex humanoid robotic system walking on an immobile/mobile platform. For this purpose, a software package was synthesized which allows one to select configuration of both the humanoid and the platform. Each joint of the biped and platform can be defined by the user via the motor state (active or locked) and gear type (rigid or elastic). The user can also form very diverse configurations of the humanoid and platform. The software package forms a mathematical model. By selecting system’s parameters the simulation allows user to analyze dynamic behavior of the biped of selected configuration, walking on either an immobile or mobile platform of selected configuration. In the moment when the biped steps on the platform, the latter, by its dynamics, acts on the biped dynamics, and the biped on the other hand, by its characteristics, influences dynamics of the platform motion. These two complex contacting systems form a more complex system, whose mathematical model has to encompass all the elements of coupling between the humanoid joints and platform joints. The phenomenon of coupling is analyzed first on a humanoid robotic system with all rigid elements, which is in contact with the platform mechanism having also all rigid elements. It has been shown that coupling is more influenced when elasticity elements are included into the configuration. Insufficient knowledge of coupling characteristics may present a serious disturbance to the system in the robotic task realization. The deviation of the ZMP (Zero-Moment Point) from the reference trajectory is presented, which implies the need for the synthesis of new control structures for stabilizing biped motion on the immobile/mobile platform. The reference trajectory may be defined in very different ways and from several aspects. Reference trajectory of each joint can be defined so to encompass or not encompass elastic deformations. The control structure for the biped walking on the platform should be defined so that it satisfies the requirement for the ZMP to be within the given boundaries in every sampling instant, which guarantees dynamic balance of the locomotion mechanism in the real regime. The control is defined as CR (Centralized Reference control, calculated from the reference state), plus LO (control via local feedbacks of motor motion with respect to position and velocity). In the case of the biped motion on a mobile platform CR control is defined separately under the real conditions of unknown characteristics of coupling between the two complex systems, as well as unknown elasticity properties. The analysis of simulation results of the humanoid robot motion on a mobile platform gives evidence for all the complexity of this system and shows how much system parameters (choice of trajectory, configuration, geometry, elasticity characteristics, motor, etc.) influence stabilization of its humanoid motion.     

Second order derivative spectrophotometric method for determination of vitamin C content in fruits,vegetables and fruit juices

A second-order derivative UV spectrophotometric method for determination of vitamin C [ascorbic acid (AA)] content in a variety of natural samples is described. The method is based on the measurement of a peak–baseline amplitude in the second derivative of the AA spectrum at 267.5 nm. The following corresponding regression equation was obtained within the concentration range 2×10^-5 to 1×10^-4 M AA (3.5–17.6 g/cm³ AA) in 1.0 M HCl solution: ²D_267.5=2.420×10⁴ c+0.025; the correlation coefficient was 0.9993 and the detection limit 4.2×10^-6 M. The results obtained by analysing 21 different species of fruits, vegetables and juices indicated a possibility for a more extensive application of the proposed method. This method is rapid, simple and requires no pretreatment of the analysed material, which makes it suitable for routine analyses. The reliability of the method was confirmed by comparative determinations with the generally accepted 2,6-dichloroindophenol method.     

Dynamic adsorption of trinitrotoluene on granular activated carbon

The effects of trinitrotoluene (TNT) dynamic adsorption on granular activated carbon produced by 'Miloje Zakic', Serbia, are presented. The main task was to determine the conditions for TNT dynamic adsorption in order to remove the dissolved TNT from wastewater. The effects of temperature, concentration and flow rate in the chromatographic system were examined. Flow rates between 1 and 4 dm(3)/h were used. The heights of activated carbon in the columns were 70 and 135 mm while the diameter was 12 mm. The experiments were conducted at different temperatures (10-60 degrees C) and TNT influent concentrations ranging from 32.76 to 171 mg/dm(3) were used. The adsorption capacity of the activated carbon increased with increasing temperature, but it decreased with increasing input concentration and flow rate. The results obtained indicate that the influence of temperature is greater than was expected and the bed height and the amount of GAC used could be significantly lowered by increasing the temperature. The possibility of desorbing TNT from saturated activated carbon was also investigated. The amount of TNT adsorbed per mass unit of adsorbent was calculated using a model that optimally agreed with the experimental data.     

Effects of serine on morphine-dependent mice

A dense AChE-positive network was visualized by light microscopy in the thoracic spinal cord of grown-up guinea pigs of both sexes (bodyweight 250-300 g). This network connects in a horizontal and vertical direction the preganglionic sympathetic nuclei (n. intermediolateralis pars principalis (ILp), n. intermediolateralis pars funicularis (ILf), n intercalatus spinals (IC), n. intercalatus pars paraependymalis (ICpe), (Petras and Cummings, 1972) all along the thoracic spinal cord. In addition to AChE activity, the bundles of fibers of this network also show a strong formaldehyde-induced NA fluorescence. Electron microscopy demonstrated granular vesicles in the cytoplasm of ILp cells. The surface of the ILp and IC neurons is almost entirely covered with synaptic bottons which have clear and granulated synaptic vesicles. The bundles of fibers consists of parallel myelin-free axones and dendrites. On their cource the axones form varicosities. In the varicosities and in the synaptic enlargements there are also clear and granulated (40-100 nm) vesicles. The probable origin of the vegetative network fibers of guinea pig thoracic spinal cord is discussed.     

The stability of zeolite/surfactant systems

The effect of various surfactants on the stability properties of zeolite dispersions has been studied in aqueous solutions. The results show a close relation between the structural properties of the interfacial solid/liquid region and the association equilibria in surfactant aqueous solutions.     

An amorphous model for morphological processing in visual comprehension based on naive discriminative learning.

A 2-layer symbolic network model based on the equilibrium equations of the Rescorla–Wagner model (Danks, 2003) is proposed. The study first presents 2 experiments in Serbian, which reveal for sentential reading the inflectional paradigmatic effects previously observed by Milin, Filipovi? ?ur?evi?, and Moscoso del Prado Martín (2009) for unprimed lexical decision. The empirical results are successfully modeled without having to assume separate representations for inflections or data structures such as inflectional paradigms. In the next step, the same naive discriminative learning approach is pitted against a wide range of effects documented in the morphological processing literature. Frequency effects for complex words as well as for phrases (Arnon & Snider, 2010) emerge in the model without the presence of whole-word or whole-phrase representations. Family size effects (Moscoso del Prado Martín, Bertram, H?iki?, Schreuder, & Baayen, 2004; Schreuder & Baayen, 1997) emerge in the simulations across simple words, derived words, and compounds, without derived words or compounds being represented as such. It is shown that for pseudo-derived words no special morpho-orthographic segmentation mechanism, as posited by Rastle, Davis, and New (2004), is required. The model also replicates the finding of Plag and Baayen (2009) that, on average, words with more productive affixes elicit longer response latencies; at the same time, it predicts that productive affixes afford faster response latencies for new words. English phrasal paradigmatic effects modulating isolated word reading are reported and modeled, showing that the paradigmatic effects characterizing Serbian case inflection have crosslinguistic scope. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

An approach to pseudo-integration of set-valued functions

The set-valued function in general is an important mathematical notion that plays a crucial role in several practical areas. This paper does not focus only on the pseudo-integration of set-valued functions in general, but also on a special case, namely on the pseudo-integration of interval-valued functions. Therefore, an approach to the integration of set (interval)-valued functions based on both classical Aumann’s approach and pseudo-analysis’ tools is given. Also, some important properties of this type of integral are investigated.     

Development and validation of a quantitative UHPLC-MS/MS method for selected brominated flame retardants in food

An ultra-high performance liquid chromatography – tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated (in-house) for the quantification of selected brominated flame retardants (BFRs), including tetrabromobisphenol A (TBBPA), hexabromocyclododecanes (HBCDs), tetrabromobisphenol S (TBBPS) and bromophenols (BPs), in various food matrices. The sample preparation consisted of extraction of TBBPS with acidified acetonitrile followed by a fast dispersive solid-phase extraction (dSPE) clean-up and extraction of the other BFRs with a mixture of hexane and dichloromethane (1:1, v/v) with subsequent clean-up using acidified silica (44%, w/w). The limits of quantification of the method varied widely for the types of food matrices and the different classes of BFRs from 4 pg g^?1 wet weight (ww) to 8 ng g^?1 ww. For most of the analytes the apparent recovery was in the range 70–120%, and the method precision (under repeatability conditions) was below 20%. The method was successfully applied in proficiency testing exercises as well as for analysis of various food items. Only 25% of the collected food samples contained BFRs, with 4-bromophenol and α-HBCD as the only detected compounds. The contaminated foodstuffs were fish and eggs with concentrations in the range from 48 to 305 pg g^?1 ww.     

Elastic liposomes-in-vehicle formulations destined for skin therapy: the synergy between type of liposomes and vehicle

Objective: The present study is focused on optimization of elastic liposomes-in-vehicle formulations in respect to drug release and formulation properties. By combining penetration potential of elastic liposomes containing high ratio of entrapped drug and physicochemical properties of vehicles, both affecting the release and texture properties, optimal formulation could be achieved.

Materials and methods: Deformable, propylene glycol-containing or conventional liposomes with hydrophilic model drug (diclofenac sodium) were incorporated into the following vehicles appropriate for skin application: a hydrogel, a cream base and derma membrane structure base cream (DMS base). Each formulation was assessed for in vitro drug release and mechanical properties.

Results and discussion: The composition and type of both liposomes and the vehicle affected the rate and amount of the released drug. The cream base exhibited the slowest release, followed by the hydrogel and DMS base. Similar release profiles were achieved with both types of elastic vesicles (deformable and propylene glycol liposomes); the slowest release was observed for conventional liposomes, regardless of the vehicle used. The drug release profiles from different liposomes-in-vehicle formulations were in agreement with the physicochemical properties of the formulations. All of the liposomes were found to be compatible with the hydrogel preserving its original textures, whereas a significant decrease in all texture parameters was observed for liposomes-in-DMS base, regardless of liposome type.

Conclusion: Propylene glycol liposomes-in-hydrogel is considered as the optimal formulation for improving skin delivery of hydrophilic drug. Further investigations involving in vivo animal studies are necessary to confirm its applicability in skin therapy.