Computer-based engineering of thermostabilized antibody fragments

We used the molecular modeling program Rosetta to identify clusters of amino acid substitutions in antibody fragments (scFvs and scAbs) that improve global protein stability and resistance to thermal deactivation. Using this methodology, we increased the melting temperature (T_m) and resistance to heat treatment of an antibody fragment that binds to the Clostridium botulinum hemagglutinin protein (anti-HA33). Two designed antibody fragment variants with two amino acid replacement clusters, designed to stabilize local regions, were shown to have both higher T_m compared to the parental scFv and importantly to retain full antigen binding activity after 2 hr of incubation at 70°C. The crystal structure of one thermostabilized scFv variants was solved at 1.6 Å and shown to be in close agreement with the RosettaAntibody model prediction.     

Stretchable Composite Acoustic Transducer for Wearable Monitoring of Vital Signs

A highly flexible, stretchable, and mechanically robust low‐cost soft composite consisting of silicone polymers and water (or hydrogels) is reported. When combined with conventional acoustic transducers, the materials reported enable high performance real‐time monitoring of heart and respiratory patterns over layers of clothing (or furry skin of animals) without the need for direct contact with the skin. The approach enables an entirely new method of fabrication that involves encapsulation of water and hydrogels with silicones and exploits the ability of sound waves to travel through the body. The system proposed outperforms commercial, metal‐based stethoscopes for the auscultation of the heart when worn over clothing and is less susceptible to motion artefacts. The system both with human and furry animal subjects (i.e., dogs), primarily focusing on monitoring the heart, is tested; however, initial results on monitoring breathing are also presented. This work is especially important because it is the first demonstration of a stretchable sensor that is suitable for use with furry animals and does not require shaving of the animal for data acquisition.     

Simulating pavement structural condition using artificial neural networks

This article aims to investigate the feasibility of incorporating of an artificial neural network (ANN) as an innovative technique for modelling the pavement structural condition, into pavement management systems. For the development of the ANN, strain assessment criteria are set in order to characterise the structural condition of flexible asphalt pavements with regards to fatigue failure. This initial task is directly followed with the development of an ANN model for the prediction of strains primarily based on in situ field gathered data and not through the usage of synthetic databases. For this purpose, falling weight deflectometer (FWD) measurements were systematically conducted on a highway network, with ground-penetrating radar providing the required pavement thickness data. The FWD data (i.e. deflections) were back-analysed in order to assess strains that would be utilised as output data in the process of developing the ANN model. A paper exercise demonstrates how the developed ANN model combined with the suggested conceptual approach for characterising pavement structural condition with regard to strain assessment could make provisions for pavement management activities, categorising network pavement sections according to the need for maintenance or rehabilitation. Preliminary results indicate that the ANN technique could help assist policy decision makers in deriving optimum strategies for the planning of pavement infrastructure maintenance.     

Three-level designs: Evaluation and comparison for screening purposes

Since their introduction by Box and Hunter, resolution criteria have been widely used when comparing regular fractional factorials designs. In this article, we investigate how a generalized resolution criterion can be used to assess some recently developed three-level screening designs, such as definitive screening designs (DSDs) and screening designs from weighing matrices. The aim of this paper is to capture the projection properties of those three-level screening designs, complementing the work of Deng and Tang, who used generalized resolution and minimum aberration criteria for ranking different two-level designs, particularly Plackett-Burman and other nonregular factorial designs. An advantage of generalized resolution, extended here to work on three-level designs, is that it offers a useful criterion for ranking three-level screening designs, whereas the Deng and Tang resolution is used mainly for the assessment of two-level designs. In addition, we applied a projection estimation capacity (PEC) criterion to select three-level screening designs with desirable properties. Practical examples and the best projections of the designs are presented in tables.     

The new external ion beam analysis setup at the Demokritos Tandem accelerator and first applications in cultural heritage

At the 5.5 MV Tandem VdG accelerator of the Institute of Nuclear Physics of N.C.S.R. “Demokritos”, Athens, Greece, an external ion-beam set-up has been recently developed and installed. The aim of this development was to integrate the analytical capabilities of the PIXE, RBS and PIGE ion beam techniques in one experimental set-up, so that to attain a complete elemental and near surface structural characterization of samples in an almost non-destructive way and without any limitation concerning their size or conductive state. A careful 3D mechanical drawing optimized the set-up experimental parameters achieving probe dimensions at the millimeter range (1 mm²) and fulfilling the special requirements imposed for optimum performance of the aforementioned techniques, including the possibility to use heavier, than protons, ion beams. For the digital pulse processing of the X-ray, γ-ray and charged particle detector signals, novel hardware and software tools were developed based on a custom FPGA configuration.The first applications were focused in the quality control of materials that have been intentionally contaminated with a particular tracer-element (“tagged” materials). The tagged materials which were developed and tested are technologically authentic replicas of ancient attic ceramics with black glazed decoration. Analytical diagnostic studies were carried out for a few representative paintings of contemporary Greek painters in order to identify and document materials/pigments and techniques and eventually to prevent trade of fakes. Finally, ancient glass beads were also examined with respect to the sodium concentration and its in-depth homogeneity.     

Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol–gel method: dissolution behaviour and biological properties after crystallisation

Hydroxyapatite (HA), fluor-hydroxyapatite (FHA) with varying levels of fluoride ion substitution and fluorapatite (FA) were synthesised by the sol–gel method as possible implant coating or bone-grafting materials. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol–water based solution. Different amounts of ammonium fluoride were incorporated for the preparation of the FHA and FA sol–gels. After heating and powdering the sol–gels, dissolution behaviour was assessed using ion chromatography to measure Ca²⁺ and PO₄ ^3? ion release. Biological behaviour was assessed using cellular proliferation with human osteosarcoma cells and alamarBlue? assay. Statistical analysis was performed with a two way analysis of variance and post hoc testing with a Bonferroni correction. Increasing fluoride substitution into an apatite structure decreased the dissolution rate. Increasing the firing temperature of the HA, FHA and FA sol–gels up to 1,000 °C decreased the dissolution rate. There was significantly higher cellular proliferation on highly substituted FHA and FA than on HA or Titanium. The properties of an implant coating or bone grafting material can be tailored to meet specific requirements by altering the amount of fluoride that is incorporated into the original apatite structure. The dissolution behaviour can further be altered by the temperature at which the sol–gel is fired.     

Upper eyelid orbicularis oculi flap with tarsoconjunctival island for reconstruction of full-thickness lower lid defects

BACKGROUND: Various cryopreservation techniques have been investigated to elongate preservation time, however, most have failed to be clinically induced because of damage due to ice crystal formation. Subzero nonfreezing conditions could theoretically reduce organ metabolism without damage due to ice crystal formation. We evaluated the superiority of subzero nonfreezing storage compared with conventional hypothermic storage using isolated rat hepatocytes stored in University of Wisconsin (UW) solution without cryoprotectants. METHODS: Hepatocytes of Wistar rats isolated by collagenase digestion were suspended in UW solution and divided into the following three groups: subzero nonfreezing group (-4 degrees C), zero nonfreezing group (0 degrees C), and control group (4 degrees C). They were stored for 48 hr at the temperatures indicated. After 24 and 48 hr of storage, we carried out a trypan blue exclusion test and a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, and measured lactate dehydrogenase release, lactic acid, ATP content, and the ability of hepatocytes to synthesize urea. After 48 hr of storage, morphological differences between the control group and the subzero nonfreezing group were investigated by scanning and transmission electron microscopy. RESULTS: Significant improvements of the trypan blue exclusion test and ATP contents in the subzero nonfreezing group were observed. Lactic acid production was also significantly suppressed in the subzero nonfreezing group compared with that in the control group. The MTT assay value was significantly better at -4 degrees C than at 4 degrees C. The rate of urea synthesis at -4 degrees C was higher than that at 4 degrees C. Electron microscopy revealed that subzero nonfreezing delayed the lethal bleb-forming process of stored hepatocytes, which was followed by mitochondrial swelling, compared with the control group. CONCLUSIONS: Subzero nonfreezing storage (-4 degrees C) in UW solution could provide better preservability for isolated rat hepatocytes with protection against hypoxic cell injury compared with conventional hypothermic storage (4 degrees C).     

Spectral estimation via selective harmonic amplification

The state-covariance of a linear filter is characterized by a certain algebraic commutativity property with the state matrix of the filter, and also imposes a generalized interpolation constraint on the power spectrum of the input process. This algebraic property and the relationship between state-covariance and the power spectrum of the input allow the use of matrix pencils and analytic interpolation theory for spectral analysis. Several algorithms for spectral estimation are developed with resolution higher than state of the art     

Dynamics of relay relaxation oscillators

Relaxation oscillators can usually be represented as a feedback system with hysteresis. The relay relaxation oscillator consists of relay hysteresis and a linear system in feedback. The objective of this work is to study the existence of periodic orbits and the dynamics of coupled relay oscillators. In particular, we give a complete analysis for the case of unimodal periodic orbits, and illustrate the presence of degenerate and asymmetric orbits. We also discuss how complex orbits can arise from bifurcation of unimodal orbits. Finally, we focus on oscillators with an integrator as the linear component, and study the entrainment under external forcing, and phase locking when such oscillators are coupled in a ring