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Chromatin structure was studied in nuclei of the endosperm of durum wheat (Triticum durum Desf., cv. Creso), where a large number of cells undergo chromosome endoreduplication during caryopsis development. Optical density profiles of interphase nuclei at different ploidy levels after Feulgen staining were determined cytophotometrically. It was observed that, within each development stage, polyploid nuclei (6–12C and 12–24C) show more condensed chromatin than euploid nuclei (3–6C): this should indicate that endoreduplication is accompanied by some reduction of nuclear activity. Within the same ploidy level, 3–6C and 6–12C nuclei become increasingly condensed with development (except for the last stage), while 12-24C nuclei are identical at all stages. DNA methylation at different stages of caryopsis development was then analyzed in genomic DNA, highly repeated sequences and ribosomal DNA, by digestion with cytosine-methylation-sensitive restriction enzymes. We observed that (i), depending on the enzyme, DNA from caryopses may show higher mean length than DNA from shoot apices and variations occur during endosperm development; (ii) highly repeated DNA sequences also show some variation in base methylation between apices and endosperms and among endosperm development stages, even though to a lesser extent than genomic DNA; (iii) rDNA shows variations only between endosperm and apices while no variation was observed among endosperm development stages in relation to chromosome endoreduplication. Our data may be explained by assuming the occurrence, during endosperm development, of processes of chromatin condensation possibly involved in silencing the activity of extra copies of DNA resulting from chromosome endoreduplication. At least in part, DNA methylation is involved in the process of chromatin condensation. rDNA shows no variation during endosperm development: this suggests that rDNA copies are actively transcribed in both triploid and endoreduplicated nuclei.

This paper represents Part I of a two-part article which summarizes the probabilistic aspects of harmonics in electric distribution systems. This first part reviews the problems associated with direct application of the fast Fourier transform to compute harmonic levels of nonsteady state distorted waveforms, and various ways to describe recorded data in statistical terms. Each statistical description is applied to a set of recorded data for illustration purposes.

Feulgen/DNA cytophotometric determinations were carried out on early prophases in the meristems of seedlings obtained by germinating seeds of different accessions of Festuca arundinacea at 10°C, 20°C, or 30°C. Feulgen/DNA contents increased significantly with the increase in the temperature of seed germination. In each accession, the greater the increase in absorption in seedlings obtained at 30°C, the lower the absorption in seedlings obtained at 10°C. In contrast, Feulgen/DNA contents did not undergo changes when the temperature was altered at developmental stages other than seed germination. The results of molecular hybridizations (slot blots) indicated that the redundancy of repeated DNA sequences belonging to two families having Cot ranges of 0–2×10-1 and 2×10-1 −2×100, respectively, was significantly higher in the genome of seedlings obtained at 30°C than in that of seedlings obtained at 10°C. When centrifuged to equilibrium in CsCl density gradients, the DNA extracted from seedlings obtained at 30°C formed a heavier and a lighter shoulder with buoyant densities of 1.707 g/ml and 1.692 g/ml, respectively, in addition to the main band (1.701 g/ml). Only a less apparent shoulder banding at 1.706 g/ml was formed by the DNA extracted from seedlings obtained at 10°C. After seed germination in the presence of [3H]-thymidine for 24 h at 30°C, most of radioactivity was found in the guanine + cytosine- or adenine+thymine-enriched DNA fractions, which formed the two shoulders in the density profile. In contrast, only guanine+cytosine-enriched fractions, which formed the heavier shoulder, were preferentially labelled in the DNA from seedlings obtained at 10°C. These results prove that fluid domains do exist in the nuclear DNA of F. arundinacea. These DNA domains are capable of rapid, quantitative alterations, which represent the direct responses of the genome to developmental and environmental stimuli. Seed germination appears to be a limited, specific period in development within which the adaptive response to temperature variations can be put into effect.

The frequency variation of highly repeated (HR) DNA sequences was studied in plants regenerated through in vitro culture of macerated vegetative apices of Pisum sativum and their progenies. Feulgen cytophotometry showed that regenerated plants (R1) have 6-7% more DNA per nucleus than control plants; this difference is maintained in the subsequent generation (R2). Slot-blot analyses using isolated highly repeated sequences as probe indicated that an increased frequency of these sequences occurs in regenerated plants and their progenies. These results were confirmed by a series of experiments: (a) metaphase chromosomes were longer in R2 than in control plants; (b) cytophotometric analyses of chromatin structure after Feulgen-staining showed that condensed chromatin is more represented in R2 than in control plants; and (c) thermal denaturation of isolated HR sequences indicated that a new HR family appears in R1 and is maintained in R2 plants. These results suggest that, in this species, the DNA extrasynthesized during in vitro culture is, at least in part, integrated in the chromosomes and transmitted to the progeny.

Nuclear DNA content, chromatin structure, and DNA composition were investigated in four Agave species: two diploid, Agave tequilana Weber and Agave angustifolia Haworth var. marginata Hort., and two pentaploid, Agave fourcroydes Lemaire and Agave sisalana Perrine. It was determined that the genome size of pentaploid species is nearly 2.5 times that of diploid ones. Cytophotometric analyses of chromatin structure were performed following Feulgen or DAPI staining to determine optical density profiles of interphase nuclei. Pentaploid species showed higher frequencies of condensed chromatin (heterochromatin) than diploid species. On the other hand, a lower frequency of A-T rich (DAPI stained) heterochromatin was found in pentaploid species than in diploid ones, indicating that heterochromatin in pentaploid species is made up of sequences with base compositions different from those of diploid species. Since thermal denaturation profiles of extracted DNA showed minor variations in the base composition of the genomes of the four species, it is supposed that, in pentaploid species, the large heterochromatin content is not due to an overrepresentation of G-C repetitive sequences but rather to the condensation of nonrepetitive sequences, such as, for example, redundant gene copies switched off in the polyploid complement. It is suggested that speciation in the genus Agave occurs through point mutations and minor DNA rearrangements, as is also indicated by the relative stability of the karyotype of this genus. Key words : Agave, DNA cytophotometry, DNA melting profiles, chromatin structure, genome size.

Complex alterations in the redundancy and methylation of repeated DNA sequences were shown to differentiate the nuclear genome of individuals belonging to single progenies of homozygous plants of the sunflower. DNA was extracted from seedlings obtained from seeds collected at the periphery of flowering heads (P DNA) or from seedlings obtained from seeds collected in their middle (M DNA). Three fractions of repeated sequences were isolated from genomic DNA: a highly repetitive fraction (HR), which reassociates within an equivalent Cot of about 2 × 10(-1), and two medium repetitive fractions (MR1 and MR2) having Cot ranges of about 2 × 10(-1)-2 and 2-10(2), respectively. Denaturation kinetics allowed different sequence families to be recognized within each fraction of repetitive DNA, and showed significant differences in sequence redundancy to occur between P and M DNA, particularly as far as the MR2 fraction is concerned. Most DNA sequence families are more represented in P DNA than in M DNA. However, the redundancy of certain sequences is greater in the latter than in the former. Each repetitive DNA fraction was hybridized to Southern blots of genomic P or M DNA which was digested to completion by three pairs of isoschizomeric restriction endonucleases which are either insensitive or sensitive to the methylation of a cytosine in the recognition site. The results obtained showed that the repetitive DNA of H. annuus is highly methylated. Clear-cut differences in the degree of methylation of P and M DNA were found, and these differences were particularly apparent in the MR2 fraction. It is suggested that alterations in the redundancy of given DNA sequences and changes in their methylation patterns are complementary ways to produce continuous genotypic variability within the species which can be exploited in environmental adaptation.

The first foliage leaf ofTriticum durum Desf., cvs. Capelli and Creso, was studied for the action of light and gibberellic acid on different aspects of plant growth. Creso is a short-strawed cultivar carrying theRht 1 gene, that influences both plant height and sensitivity to applied gibberellins. In this study, a cytophotometric analysis of chromosome endoreduplication in bulliform cells of the leaf epidermis was undertaken. The bulliform cells are arranged in long rows and comprise 4C, 8C, and 16C cells. The relative percentage of these cells was recorded under different light regimes and in the presence or absence of gibberellic acid (GA3). Our data indicate that light strongly affects the occurrence of chromosome endoreduplication. Although cvs. Cappelli and Creso show the same frequency of endo-reduplicated cells in the dark, all light treatments induce lower endo-polyploidy in cv. Creso whereas, in cv. Cappelli, a reduction in endo-polyploidy is observed when plants are irradiated with blue-lacking lights. This indicates that the action of a blue-light responsive photo-receptor determines high endopolyploidy. With respect to GA3 treatment, cv. Creso is again shown to be insensitive to hormone application, whereas in cv. Cappelli, gibberellic acid influences endopolyploidy level in the dark, causing very high frequencies of 8C cells and relatively high frequencies of 16C cells.

Chromosome endoreduplication is a very common process in higher plants but its function and genetic control are still to be clarified. In our experiments we analyzed, by Feulgen cytophotometry, chromosome endoreduplication in endosperm cells of two maize genotypes, IHP and ILP, having high and low protein content in their seed, respectively. Chromosome endoreduplication occurs in both lines within 24 days after pollination, attaining a maximum ploidy level of 384C (7 DNA replication rounds) in IHP and of 192C (6 replication rounds) in ILP. In the mature seed, endosperms of the two lines show different mean ploidy level. In reciprocal crosses between IHP and ILP the f1 endosperms have mean ploidy levels analogous to that of the maternal parent, showing that the difference in ploidy level between the two genotypes is maintained. After selfing of the f1 plants, the difference in ploidy level between the two F2 populations is reduced. In F2 the mean ploidy level is as variable as in f1, indicating the absence of genetic segregation. From our data, it is apparent that both the genetic constitution (cytoplasmic and nuclear) of the maternal parent and the genotype of the individual endosperms influence the ploidy level. An analysis of the protein content in endosperms carried out on the same seed sample as analyzed cytophotometrically showed that the protein content increases, during seed development, parallel to chromosome endoreduplication and varies, in the two lines, in reciprocal crosses and their progeny, according to the same trend as mean ploidy level, suggesting a correlation between the two parameters.

Plant regeneration from cotyledons of seeds of a single progeny of a pure line of Helianthus annuus was studied in respect of the nuclear DNA contents of control and regenerated plants. Control plants were divided into two groups: those developed from seeds at the periphery of the inflorescence (showing a high basic 4C DNA content) and those from seeds developed in the middle of the inflorescence (showing a low basic 4C DNA content). It was observed that plants from peripheral seeds have a higher morphogenetic potential than those from central seeds. Cytophotometric analyses indicated that plants regenerated from cotyledons of both peripheral and central seeds show the same basic 4C DNA amount, which is higher that that observed in vivo in peripheral seeds. Molecular analysis by slot blotting and hybridization with different DNA families showed that the difference in nuclear DNA content between plants from peripheral and central seeds in vivo are mainly related to differences in the frequency of highly repeated, “slow” medium repeated (MR2), and ribosomal DNA families; by contrast, the increase in DNA amount in regenerated plants is mainly due to “fast” medium repeated sequences (MR1). Moreover, the frequency of kinetically isolated “unique” sequences was higher in peripheral seeds than in central ones and still higher in regenerated plants. Optical-density measurements of interphase nuclei showed an increase of heterochromatin in regenerated plants, suggesting that, whatever DNA is amplified in these plants, it remains condensed and probably inactive.

The common sunflower (Helianthus annuus L.) is a member of the Compositae (Asteraceae) family. Its name (from the Greek helios, sun, and anthos, flower) is derived from the heliotropic movement of the sunflower’s head (nutation). Grown for its seed, this species is one of the most important suppliers of vegetable oil, and is now fairly widely cultivated throughout the world.

A loe belongs to the Liliaceae family. The name is derived from the Arabic “alloeh”, which is the name used by the natives of eastern Africa, where the plant was first cultivated. The genus comprises about 300 perennial species (Reynolds 1985), native to both eastern and southern Africa. The juice from the leaves of certain species yields a medical substance, the “aloe” drug. The drug was found cited in Ebers’ papyrus and in the works of Dioscorides. Various species were introduced into and cultivated in the dry area of Africa, in the mountains of tropical Africa, in the Antilles, in India, and in the Mediterranean basin.

A method for rapid and highly effective plant micropropagation from vegetative meristems was established for Aloe barbadensis Mill. Plant micropropagation was achieved culturing apices on medium containing 1.1 μM 2,4-dichlorophenoxyacetic acid and 2.3 μM kinetin for 15–30 days. High morphogenetic ability was maintained by transferring explants (after 60 days) on media containing 0.11 μM 2,4-dichlorophenoxyacetic acid and 2.2 μM 6-benzylaminopurine.

This paper represents the second part of a two-part article reviewing the state-of-the-art of probabilistic aspects of harmonics in electric power systems. It includes tools for calculating probabilities of rectangular and phasor components of individual as well as multiple harmonic sources. A procedure for determining the statistical distribution of voltages resulting from dispersed and random current sources is reviewed. Some applications of statistical representation of harmonics are also discussed.

The development of epidermal cell lines in the first foliage leaf ofTriticum durum was studied with a combined cytological and DNA cytophotometric analysis. It was shown that: (1) At emergence, the distal portion of the leaf is made of the cells pre-existing in the embryonic leaf and the mitotic activity is localized at the base of the leaf lamina (basal meristem). (2) The proliferating protoderm (outermost cell layer of the basal meristem) contains a meristematic cell population and a differentiating cell population. The cells produced by the protoderm differentiate with 2C, 4C, 8C, and 16 C nuclear DNA contents. (3) The endoreduplicated cells (EC) together with 4C cells form prominent cell rows in the leaf epidermis. The interstomatal cells (ISC) are all 2 C and the inter-hairs cells (IHC) are mostly 2 C (rare 4 C cells lie adjacent to the EC). (4) In the fully developed leaf, the frequency distribution of EC (8 C and 16 C) and 4C cells in a given epidermal segment (Fig. 1) corresponds to the frequency established in the epidermis differentiation zone (zone b, segment 1) at the time of development of that segment:e.g., segment 6 developed at 1–2 days after seed germination, segment 5 at 3 days after germination and so on. (5) Epidermal cell elongation starts in segment 1 and reachs its maximum in the older leaf segments, 5 and 6. The rate of cell elongation is independent of nuclear DNA content; chromosome endoreduplication precedes elongation. (6) The possibility of using epidermal cell parameters in studies on first leaf growth inT. durum is discussed.

Bellevalia romana (L.) Rchb., a monocotyledonous plant characterized by few (2n=2x=8) and very large chromosomes, may regenerate plants bothvia adventitious bud differentiation andvia somatic embryogenesis in suspension cultures. Cytological analysis of numerous embryoids at different developmental stages in most of them revealed a mixoploid and aneusomatic condition which increased during embryo growth. Only globular proembryos were all entirely diploid. The results are discussed in relation to: i) the origin of the embryos; ii)de novo induction and increase in abnormal metaphases during embryogenesis; iii) embryo inability to develop into plant owing to chromosomal mosaicism.

DNA sequences reassociating within a Cot value of 1.8×10−1 and those producing a light satellite in a CsCl density gradient were isolated fromVicia faba DNA and hybridizedin situ on squashes of roots of the same species. Silver grains were seen to be scattered over both the interphase nuclei and the metaphase chromosomes after hybridization with fast renaturing DNA sequences, indicating these are fairly regularly interspersed in theV. faba genome. Clustered labeling occurred after hybridization with satellite DNA sequences, indicating these are clustered in the genome. The localization of satellite DNA in chromosomes appeared to correspond closely to the position of the bright bands detectable after staining with quinacrine mustard. After hybridization with both DNA probes, labeling intensity over the nuclei of meristematic cells was higher than that over the nuclei of differentiating and/or differentiated cells. These results are discussed in relation to the structure of the cell nucleus, the mechanism of quinacrine banding and to previous data suggesting underrepresentation of nuclear repeated DNA sequences in differentiatingV. faba root cells.

By means of karyological, cytophotometric, and autoradiographic analyses it has been shown that, owing to alterations in the DNA synthesis – mitosis sequence, cells with different nuclear conditions are continuously formed de novo and proliferate in Phaseolus coccineus meristems. Besides diploid cells, the following also occur: (i) polyploid cells as the result of chromosome endoreduplication followed by mitosis; (ii) haploid cells as the result of the separation of the two groups of homologous chromosomes in cells that have omitted DNA reduplication; and (iii) since haploid cells undergo chromosome endoreduplication and divide, isogenic cells can be produced. Diploid mitoses alone are present in the meristems of early embryos; haploid mitoses first appear in both root and shoot meristems with increasing embryo development, followed later by cells undergoing chromosome endoreduplication. The study of the root apex has shown that neither polyploid nor reduced cells occur with the same frequency in its various portions. These results are discussed in relation to pertinent data in the literature and the mechanisms responsible for the occurrence of polysomaty and somatic reduction are suggested.Key words: isogenic cells, Phaseolus coccineus, polysomaty, somatic reduction.

Cytophotometric and biochemical analyses indicate changes with plant development in the amount and organization of the nuclear DNA in epidermal and subepidermal tissues excised from different portions of tobacco stems: DNA is progressively lost with tissue ageing, while amplification of repeated sequences occurs in tissues developed after phase change. These genome variations are related to the morphogenetic response of the tissues cultured in vitro, which differs both quantitatively and qualitatively: loss of DNA sequences progressively impairs morphogenetic capability; DNA amplification may be a factor of the explant's ability to regenerate flowers. These results point to the possible role of the nuclear DNA condition of differentiated tissues in determining their morphogenetic expression in vitro.

Plant regeneration was achieved from immature embryo-derived, calli of Pisum sativum. Embryo axes were separated from cotyledons and cultured on different media containing BAP and NAA until plantlet regeneration. Rooting of the plantlets was obtained on MS medium supplemented with 2 mg/1 IBA. Frequency of regeneration was shown to be under the influence of the genotype. Histological preparations showed de novo origin of the shoots via organogenesis. Out of 2C regenerated plantlets, 11 were diploids (2n = 14) arid 9 aneusomatic (chromosomal mosaics) with chromosome numbers ranging from 12 to 16.

Cell dedifferentiation was induced inVicia faba root tissues by removing the whole root meristem (decapitation) and the behaviour of the nuclear DNA in the dedifferentiating cells was studied by means of cytophotometric and autoradiographic analyses. Cytophotometric determination after Feulgen-staining showed that: 1. the vast majority of nuclei in differentiated cells were in the DNA postsynthetic phase, but their Feulgen absorption was lower than that of DNA postsynthetic nuclei (G2, 4 C) in the meristem; 2. such a Feulgen absorption was detected in certain nuclei after root decapitation; 3. all the mitoses in the dedifferentiating tissues were diploid, fully matching the Feulgen absorption of mitoses in the meristem.

Chromosomal variability in Helianthus annuus was studied during the ontogenetic cycle of the plant. Aneusomaty originates during embryo development, progressively decreases in the course of plant growth and disappears at pre-meiosis. A number of aberrant mitoses with lagging chromosomes were found in all embryonic stages examined; by contrast, mitoses never showed aberrations in the shoot apices of plants.

Different regions of polytene chromosomes pair VI have been characterized by: 1. morphological observations, 2. incorporation of3H-thymidine and3H-uridine, 3. cytophotometry of DNA and associated proteins, 4. hybridization with satellite DNA and highly repeated DNA sequences. The collected data indicate that DNA and RNA puffs are organized by heterochromatic segments. DNA puffs show often a clustered pattern of labeling by3H-thymidine and RNA puffs are always labeled by3H-uridine. Each heterochromatic segment is characterized by a definite ratio between DNA and associated fast-green stainable proteins. Satellite DNA binds mostly to heterochromatic blocks at centromere, highly repeated DNA sequences bind, with approximately the same frequency, to centromeric heterochromatin and to the main intercalary heterochromatic band. The telomeric portions of euchromatin seem to be also enriched in highly repeated DNA sequences. The results indicate that heterochromatic chromosome segments might be sites of intense localized DNA replication. The same chromosome regions are also engaged in an active transcription process. The response to hybridization suggests that heterochromatic blocks of chromosome pair VI are heterogeneous in nucleotide sequences. The present studies also indicate that DNA and RNA puffs organized by different chromosome sites are specific of particular steps of embryo differentiation. The observed metabolic aspects of the suspensors's polytene chromosomes are discussed in relation to the synthesis of growth regulators which is known to occur in the suspensor.

Previous results suggested that the amount of nuclear DNA varies in one and the same progeny of Helianthus annuus, depending on the head portion in which seeds have developed. Accordingly, cytophotometric determinations were carried out in a selfed line, after Feulgen-staining, to obtain information on the developmental stages at which DNA changes are produced and on the mechanism controlling the variation. It was found that the Feulgen absorption values of mitotic prophases in immature anthers and pistils and of meiotic prophases I are the same in any flower of the head. In contrast, the Feulgen/DNA contents of early prophases in heart-shaped embryos differ significantly, increasing from those developing at the centre of the head to those developing at its periphery, and remaining unchanged in each embryo during further development and seed germination. Variations in the number of chromosomes do not account for the differences observed in nuclear DNA contents in which sequences comprised in heterochromatic nuclear regions are involved. The Feulgen absorption values of seedlings obtained from seeds developed in different portions of single heads increase or diminish starting from those found in the mother plant. This depends on whether these latter are relatively low or high and on the gradient of seed location in the head. The variation occurring within each single progeny covers the whole range existing within the line.

Cell dedifferentiation has been induced in Vicia faba roots by removing the whole meristem (decapitation). When centrifuged to equilibrium in CsCl density gradient, the DNA from dedifferentiating tissues forms a heavier satellite, not occurring in the DNA from differentiated tissues. Most of the radioactivity after [3H]thymidine feeding is found in the satellite DNA. Its sequences have a well defined nuclear localization, as shown by in situ hybridization experiments. These results indicate amplification of G + C-rich nuclear DNA sequences during cell dedifferentiation.

In vitro culture of shoot apical meristems of Helianthus annuus was studied to determine the cytological condition of calli and regenerated shoots. A broad chromosome mosaicism (aneusomary) in bath callus and regenerated shoots was found, reflecting the cytological conditions of the explain. During in vitro plant development, a diplontic selection took place that was more rapid when very precocious in vitro flowering occurred.

Cytophotometric measurement of the root meristems of seedlings after Feulgen-staining reveals that large differences (up to 58.16%) in nuclear DNA content may occur in the thirty-one cultivated varieties or lines of Helianthus annuus tested. Significant variations (not exceeding 25%) in the amount of DNA, which does not differ between the root and the shoot meristems of a single seedling, are also found to exist within cultivars or lines; even seedlings obtained from seeds collected from different portions of single heads of plants belonging to a selfed line may vary one from the other in this respect. Variations in the number of chromosomes or alterations in the chromosome structure do not account for the differences observed in nuclear DNA content. Karyometric analyses demonstrate that the surface area of squashed interphase nuclei and metaphase chromosomes and the total length of the latter increase with the increase in Feulgen/DNA absorption. DNA thermal denaturation and reassociation kinetics indicate that a frequency variation in repeated DNA sequences goes hand in hand with changes in the size of the genome. These results, supporting the concept that a plant genome is highly flexible, are discussed in relation to other data to be found in the literature on the intraspecific variation in the nuclear DNA content and in relation to the way in which it is produced in H. annuus.

Somatic embryogenesis was obtained through in vitro culture of roots, leaves, mesocotyls and bulb scales of Brimeura amethystina Salisb. Embryogenesis was achieved both on the primary explant and after callus formation. The highest frequencies of both callus and embryo formation were obtained when using media containing 6-benzylaminopurine (BAP) and naphthaleneacetic acid (NAA). Complete plantlets were obtained by inducing adventitious rooting on hormone free medium. A cytological and cytophotometric study of embryos and plantlets was undertaken to explain the observed frequent failure of embryo development after the globular stage: a great variability of nuclear DNA content was found among non-developing embryos in respect of normal ones.

We report the first selective growth of nanographite petals and various carbon nanomaterials onto a multipanel electrochemical platform. Different types of nanomaterials can be obtained by fine-tuning the growth parameters of the chemical vapor deposition (CVD) process. First, absolute novelty is the catalytic CVD selective growth of different carbon nanomaterials only on the working electrodes of the platform. A second novelty is the growth obtained at complementary metal–oxide–semiconductor compatible temperatures. These novel electrodes have been incorporated in sensors in which performance characteristics improve with the content of nanostructures. Unprecedented sensing parameters with respect to both direct and enzyme-mediated electrochemical biodetection have been obtained.

Electric motors for aerospace applications are often characterised by short-time duty rather than continuous-duty operations. Some of the main requirements for these machines are high torque density and reliability. Considerable torque density improvement can be achieved by supplying the windings with current greater than the rated value and thus thermally overloading the machine for short periods of time. However, if the insulation is overheated, the machine lifetime is shortened, and reliability issues can arise. This paper experimentally investigates the influence of short-time thermal overload on the insulation lifetime of low voltage, random wound electrical machines. The analysis is performed on round enamelled magnet wires coils aged by accelerated thermal cycles, and the results are statistically processed by the two-parameter Weibull distribution. The experimental data is also used for building a lifetime estimation model, which is employed for predicting the lifetime of a motor embedded into an electromechanical actuator for landing gear extension/retraction.

During online partial discharge (PD) measurements on AC rotating machines, one of the noise typologies that affects PD patterns is the so called "cross-talk", that is, discharges that appear in the tested phase as a result of coupling from another phase. An approach to cross-talk recognition, based on PD-pulse shape and phase analysis, is presented in this paper. It is shown that, the signal distortion, due to the different propagation path, can help in separation of PD signals relevant to the main and cross-talk PD patterns. The cross-talk recognition can be achieved applying appropriate phase shift analysis to the separated PD patterns. The rejection of cross-talk patterns can make easier PD source identification and the relevant diagnostic decision can be more reliable.

Robust and reliable measurements in electrochemical biosensing of molecules are crucial for personalized medicine. Electrochemical sensors based on cytochrome P450 can detect the large majority of drugs commonly used in pharmacological treatments. The same cytochrome can detect different substrates; each of them changes the electrochemical response of the enzyme in a specific manner. Our system exploits the measure of electrical potential to identify the drug type, while current measurements decode the drug concentration. Since potential and current are affected by pH and temperature, and since variations occur in the patient samples, we propose a novel design for multiplexing biosensing with pH and temperature control, which ensures more precise measurements for drugs identification and their quantification.

Aim of this paper is to validate the effectiveness of an artificial intelligence technique devised for tree diagnosis in solid insulation systems. For this purpose, electrical and optical partial discharge (PD) measurements were carried out on specimens containing treed regions of different typologies ("bush" and "branch"). The results obtained by the above-mentioned diagnostic procedure were checked on the basis of the tree typology.

This paper compares three different biocompatible packaging covers suitable to support full implantation of multi-panel sensors for remote monitoring of metabolism. The three covers have been designed, realized and implanted in mice for 30 days. ATP and neutrophil concentrations have been measured at the implant site after the device was explanted, to assess the level of biocompatibility of the device.

A highly integrated system for remote monitoring of several human metabolites is proposed. It is obtained by integrating several components, such as: bio-probes, carbon nanotubes, micro-fabricated gold-electrodes, temperature and pH sensors, extremely small CMOS IC and multilayer coil for remote powering data acquisition and transmission. The entire system has final sizes of only 2.2 mm in width and thick and it is long 1.5 cm. In this paper, results on sensors micro-fabrication, sensing tests, IC design, and power transmission are presented. These results confirmed that the proposed approach is suitable for minimally invasive monitoring of multi-metabolites in humans.

A novel system for remote monitoring of metabolism in animal model is proposed in this paper. The system is obtained by integrating Bio-Nano-Sensors to detect single- metabolites, an electrochemical front-end made with off- the-shelf components, an RF communication sub-system, and an antenna of new design. The system has been calibrated and tested for continuous monitoring of four different metabolites: glucose, lactate, glutamate, and adenosine triphosphate (ATP). Tests with animal models (mice) have been conducted to investigate tissue inflammation induced by the implanted Bio-Nano- Sensors. The tests confirmed that our system is suitable and reliable for remote monitoring of single-metabolites in experiments with animal models.

An amperometric biosensor for adenosine 5 -triphosphate (ATP) was developed applying a competitive assay of two glucose converting enzymes: glucose oxidase (GOD) and hexokinase (HEX). Competition between GOD and HEX for glucose in presence of ATP, lead to a decrease in the current coming from the hydrogen peroxide generated by the GOD, and allows ATP detection. The biosensor was realized on commercial screen-printed electrodes modified with carbon nanotubes (CNTs). Confinement of CNTs in a polycarbonate membrane, Chitosan and Nafion polymers was investigated as possible solutions for implantable sensors. Nafion gave the best performances, with a sensitivity of 25 pA/μM mm-2, and a detection limit of 257 M. The sensor resulted able to measure ATP concentrations in the range of hundred of μmol/l.

This paper presents the results of space charge and partial discharge measurements carried out on enameled wires, specifically designed to be used in electrical motors fed by adjustable speed drives. These procedures described can provide a useful tool for short-term evaluation of enameled wires, which can give indications also on long-term performance. Partial discharges and space charge accumulation seem to be significantly influenced by the supply voltage waveform features (frequency and shape), with an extent depending on the material itself. Moreover, partial discharge features, such as pulse height and inception voltage, depend considerably on space charge accumulation which may occur, e.g., with unipolar waveforms. Both techniques provide considerably different fingerprints of the two tested kinds of wires.

Biosensing for chronic pathologies requires the simultaneous monitoring of different parameters such as drug concentrations, inflammation status, temperature and pH. In this paper we discuss the design, fabrication and test of a sensor array hosting five biosensor platforms, a pH electrode and a temperature sensor. Different and reproducible nano-bio- functionalization can be obtained with high spatial resolution via selective electrodeposition of chitosan/MWCNT/enzyme solutions at the various electrodes. The array, completely fabricated with biocompatible materials, can be integrated with a CMOS integrated circuit and a remote powering coil for the realization of a fully implantable device.

The aim of this paper is to derive PD-based indexes and criteria that are able to indicate whether an internal defect, a cavity, is located close to the HV electrode, to the ground electrode, or in the bulk of the insulation. For this purpose, several measurement sessions were carried out on laboratory samples whose geometry was suitably designed (CIGRE type I and type II cell). In addition, measurements were performed on a capacitive insulator, having known location defects. The measurements results and their evaluation are described in the paper. It is shown that indexes useful for PD source location can be extracted from PD phase distributions.

This paper discusses the application of Hilbertian auto regressive models to medium term forecasting of electric energy demand, that is, one week-ahead prediction. These models are aimed at predicting whole future trajectories of continuous stochastic processes and can be useful in order to forecast not only the aggregate figures of energy demand (e.g., mean levels and load peaks), but also the time evolution of electrical quantities. Consideration on the optimum number of weeks which should be employed in order to achieve the minimum-variance prediction as well as on the robustness of the model to particular data and outliers, due, for example, to sudden weather changes, are reported.

This paper presents a new identification technique, based on fuzzy logic, which enables the recognition of PD generated from different sources, such as internal, surface and corona discharges. It is shown that the different sources typologies can be identified on the basis of fuzzy rules applied to a selection of parameters derived from PD-pulse phase and amplitude distributions. The proposed procedure is finally applied to rotating machines and cables, with real insulation defects, showing promising on-field applications.

Partial discharges, which may occur in motor windings supplied by power converters, are associated with space charge accumulation. Space charge is able to modify the electric field which sustains partial discharges, affecting amplitude, repetition rate and inception voltage. This paper presents a simplified model which takes into account the dynamic of charge accumulation generated by the partial discharge process. In particular, among electrical properties surface conductivity is considered and related to the electric field governing partial discharge activity.

A novel system for remote monitoring of metabolism in an animal model is proposed in this paper. The system is obtained by integrating bio-nano-sensors to detect single- metabolites, an electrochemical front-end made with off-the-shelf components, a radio frequency communication sub-system, and an antenna of new design. The system has been calibrated and tested for continuous monitoring of four different metabolites: glucose, lactate, glutamate, and adenosine triphosphate. Tests using animal models (mice) have been conducted to investigate tissue inflammation induced by the implanted bio-nano-sensors. These tests confirm that our system is suitable and reliable for remote monitoring of single-metabolites in experiments with animal models.

Background Retrotransposons are heterogeneous sequences, widespread in eukaryotic genomes, which refer to the so-called mobile DNA. They resemble retroviruses, both in their structure and for their ability to transpose within the host genome, of which they make up a considerable portion. Copia- and Gypsy-like retrotransposons are the two main classes of retroelements shown to be ubiquitous in plant genomes. Ideally, the retrotransposons life cycle results in the synthesis of a messenger RNA and then self-encoded proteins to process retrotransposon mRNA in double stranded extra-chromosomal cDNA copies which may integrate in new chromosomal locations. Results The RT-PCR and IRAP protocol were applied to detect the presence of Copia and Gypsy retrotransposon transcripts and of new events of integration in unstressed plants of a sunflower (Helianthus annuus L.) selfed line. Results show that in sunflower retrotransposons transcription occurs in all analyzed organs (embryos, leaves, roots, and flowers). In one out of sixty-four individuals analyzed, retrotransposons transcription resulted in the integration of a new element into the genome. Conclusion These results indicate that the retrotransposon life cycle is firmly controlled at a post transcriptional level. A possible silencing mechanism is discussed.

The document IEC 60034-18-41 for inverter-fed rotating machines is undergoing a radical revolution: born as a technical specification, it is going to become a standard. One of the points that will influence most strikingly machine manufacturer-customer relations is the concept of impulse rated voltage (IRV): a quantity that will be printed on the machine nameplate and needs to be explained. Also, as wire-wound insulation systems are qualified or not depending on partial discharges measurements, it is vital to face the challenges of partial discharge detection under repetitive surge voltages. According to the above, this paper will first summarize the main features of the IEC 60034-18-41 document. After that, a short description of a system able to detect partial discharge under repetitive voltage surges and its applications will be presented.

This paper presents a procedure for the investigation of partial discharge (PD) sources in PWM-controlled motors, based on off-line measurements under bipolar squarewaves. PD measurements were carried out on three-phase motors with open-star windings and different configurations, e.g., one phase supplied while the other two were grounded, two phases connected in series, grounding the motor frame. The voltage waveforms generated by a power supply and applied to motor windings was recorded at the winding terminals, for each test configuration. These measurements allowed to highlight winding positions where insulation can be overstressed by uneven voltage distribution, as occurs on motors in service. By comparing partial discharge measurement patterns along windings and under different test configurations, a qualitative evaluation of the location of partial discharge sources inside the tested motors was carried out.