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The transfer of photogenerated charges through interfaces in heterojunction photoanodes is a key process that controls the efficiency of solar water splitting. Considering Co3O4/SiOx/Si photoanodes prepared by physical vapor deposition as a representative case study, it is shown that defects normally present in the native SiOxlayer dramatically affect the onset of the photocurrent. Electron paramagnetic resonance indicates that the signal of defects located in dangling bonds of trivalent Si atoms at the Si/SiOxinterface vanishes upon vacuum annealing at 850 °C. Correspondingly, the photovoltage of the photoanode increases to ≈500 mV. Similar results are obtained for NiO/SiOx/Si photoanodes. Photoelectrochemical analysis and impedance spectroscopy (in solution and in the solid state) indicate how the defect annealing modifies the Co3O4/SiOx/Si junction. This work shows that defect annealing at the solid–solid interface in composite photoanodes strongly improves the efficiency of charge transfer through interfaces, which is the basis for effective solar-to-chemical energy conversion.

Vanadium pentoxide thin films are grown on glass and borosilicate substrates by PACVD using a vanadyl (IV) β-diketonate as precursor. The depositions are carried out in an RF-plasma reactor with Ar-O2mixtures and soft process conditions, obtaining high-purity nanocrystalline layers with a strong preferential orientation. The microstructural and morphological characteristics of the films, analyzed respectively by XRD and AFM, show that the sample features can be accurately tailored by an adequate choice of the synthesis conditions. The composition and purity of the films are studied by XPS and SIMS analyses. Impedance Spectroscopy is used to study the conductivity of the layers and the dependence of electrical properties on microstructure.

A volatile molybdenyl complex was used as precursor for MOCVD of MoO3films. Decomposition paths were investigated by thermal analysis. Good quality films were obtained on different substrates and characterized by XPS, UV-Vis, XRD and SEM analyses. The different electronic properties of the various films on different substrates were studied by photoemission experiments and compared with respect to the MoO3single crystal.

Zirconium tetra-tert-butoxide was used as precursor for the growth of ZrO2films on TiO2(110) in ultrahigh vacuum conditions. The composition of the film was characterized by X-ray photoelectron spectroscopy (XPS), while its thickness and growth mode were characterized by angle-resolved photoelectron spectroscopy (AR-XPS). The structure of the interface was studied in detail by angle-scanned X-ray photoelectron diffraction (AS-XPD). These data, compared with multiple-scattering spherical wave (MSSW) simulations suggest the growth, at the interface, of Zr2O3nanostripes aligned along the [001] direction. The structure and composition of the interface are responsible for the lower acidity of the ZrO2/TiO2(110) surface if compared with that of the bare substrate.

Although thermal barrier coatings are used in industry for several decades there is still considerable demand for a further improvement of this coating system. Present research projects are for example dealing with the improvement of temperature capability and lifetime, developing of lifetime models, new processing technologies, or incorporating of additional functional properties in the coating. The present paper tries to give an overview on these recent research activities. In addition, it will also try to describe the different burner rig test facilities in Europe, which serve as an important test bed of thermal barrier coating systems.

Linearly polarized soft X-ray absorption spectroscopy experiments both on Ni L2,3and O K edges have been carried out on NiO ultrathin films on Pd(100), from the c(4 × 2) defective monolayer up to fully relaxed films. In the defective monolayer a dichroic effect on the Ni L2,3edge has been detected, and it has been associated to anisotropic structural effects (e.g., local crystal field symmetry) due to the spatial confinement. This produces a change in the energy sequence of the Ni 3d levels resulting in different transition probabilities for the various levels at different polarization. A support to this interpretation has been also obtained by theoretical computations. In the case of thicker films, a clear dichroic effect, reversed with respect to the one observed for a bulk like NiO(100) surface, has been observed for the L2white line at all the explored thicknesses. This has been associated to a different spin structure of the ultrathin films, where the domains are preferentially aligned to the surface plane instead of being perpendicular to it. However, we have not observed the inversion of dichroism even for very thick fully relaxed films. The dependence of the dichroic effect on the preparation procedure of the films has been also explored. For the thicker films the dichroic effect is independent from the actual oxygen pressure used during the growth, while remarkable differences are found in the case of the thinner films.

Abstract: High-temperature thermal fatigue causes the failure of thermal barrier coating (TBC) systems. This paper addresses the development of thick TBCs, focusing on the microstructure and the porosity of the yttria partially stabilized zirconia (YPSZ) coating, regarding its resistance to thermal fatigue. Thick TBCs, with different porosity levels, were produced by means of a CoNiCrAlY bond coat and YPSZ top coat, both had been sprayed by air plasma spray. The thermal fatigue resistance of new TBC systems and the evolution of the coatings before and after thermal cycling was then evaluated. The limit of thermal fatigue resistance increases depending on the amount of porosity in the top coat. Raman analysis shows that the compressive in-plane stress increases in the TBC systems after thermal cycling, nevertheless the increasing rate has a trend which is contrary to the porosity level of top coat.

The author examines the main attempts of the translation of the LXX underway, under an hermeneutical profile. The ancient Greek version of the Jewish Miqraot, or the Old Testament of the Christian communities introduces, regarding the Hebrew text, a complex phenomenology of differentiations on different levels: textual, grammatical, syntactical, lexicografical, stilistical and hermeneutical. In this way, the characteristics of the LXX under the hermeneutic profile emerge with more clarity because of the comparison with the ancient Jewish Greek versions and with the Syriac and Latin versions transmitted in various Christian contexts. In any case, the phenomena interpreted in an ancient version belong to the nature of translation, independently from their confessional origin. Considering the task of an Italian translation of the LXX in the Jewish context, and then transmitted in a Christian context, the author thinks that it is necessary to equip the translation with an hermeneutic apparatus formed from the New Testament quotations of the Greek version and from the Christian literature of the Greek speaking Church Fathers of the first centuries. Moreover, a theological clarification is necessary between these hermeneutics of the LXX in the ancient Christian tradition, the text Hebrew, the jewish atmosphere at the time of the LXX before it was handed over up to modern Biblical Hermeneutics.

Phase-contrast microtomography, performed at the beamline ID 22 of the European Synchrotron Radiation Facility (ESRF, Grenoble, France), is demonstrated for high-resolution 3-D imaging of a hydroxyapatite sample. The technique, which relies on phase contrast imaging, gives the possibility to observe features inside samples with negligible absorption contrast. The positive results obtained suggest a possible future investigation of the influence of the distribution of pores and defects inside biomaterial coatings, on the growth of osteoblast cells.

One of the most important factors determining the degree of tissue interaction of an implanted device is the property of its surface. Thus, great importance is given to chemical and morphological characteristics of biomaterial surfaces to improve biocompatibility, cell migration, proliferation and differentiation, mechanical stability and endogenous tissue ingrowth.In order to obtain new and healing stimulating properties, it is possible to apply a coating or more generally a surface treatment to the surface of a prosthetic device. One of the most versatile methods for coating is thermal spray technology. This paper considers the principle of thermal spray processes and their application in the biomedical field, namely the coatings used for orthopedic prostheses and dental implants. Among thermal spray processes, plasma spray as well as High Velocity Oxygen Fuel (HVOF) processes will be particularly considered and their most important aspects will be illustrated.

Abstract: In the aerospace field as well as in the stationary gas turbine field, thermally sprayed coatings are used to improve the surface properties of nickel-super-alloys materials. Coatings are commonly used as bond coat and antioxidation materials (mainly MCrAlY alloys) and as thermal barrier coatings (mainly yttria partially stabilized zirconia). The purpose of the current study was to assess the properties of thermally sprayed bond coat CoNiCrAlY alloys comparing the performance of three different techniques: vacuum plasma spray (VPS), high velocity oxygen fuel (HVOF), and axial plasma spray (AxPS). The quality of the deposited films has been assessed and compared from the point of view of microstructural (porosity, oxide concentration, unmelted particles presence) and mechanical (hardness) characteristics. The surface composition and morphology of the coatings were also determined. Specific efficiency tests were performed for the three examined technologies. The highest quality coatings are obtained by VPS, but also high velocity oxygen fuel and AxPS sprayed films have interesting properties, which can make their use interesting for some applications.

Triruthenium dodecacarbonyl (Ru3(CO)12) adsorption and decomposition on titania (TiO2) were studied using infrared reflection absorption spectroscopy, temperature-programmed desorption, Auger electron spectroscopy, and scanning tunneling microscopy. It was found that the vapor-deposited cluster adsorbs with the Ru3 plane oriented normal to the surface. The clusters form an amorphous layer at 90 K, order at 195 K, and begin to decompose in a vacuum at ca. 250 K. The clusters decompose in two stages, with complete decomposition occurring above 600 K. The clusters are highly dispersed on the surface and decompose cleanly to form small ruthenium clusters up to 3 nm across and single atom rows up to 20 nm long.

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The appropriate selection of bulk materials and coatings of valve components is an important factor for the economic success of oil and gas production activities in the petrochemical field. Materials and coatings are important because particle erosion and surface wear are associated to corrosion by hydrogen sulphide during oil and gas flow. The wear of high pressure valves of gas system will lead to pollution, safety problems and cost increases. The most common solution of these problems is the deposition of hard materials as tungsten carbide or chromium carbide by thermal spray. These coatings are deposited by high velocity oxygen fuel (HVOF) thermal spray process to obtain a very high hardness with excellent cohesion and adhesion. Tungsten carbide cobalt–chromium based coating, chromium carbide nickel–chromium coating as well as Inconel 625 have been adopted in the specifications of petrochemical companies and their behaviour and wear, erosion and corrosion properties are reported in the literature.

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Plasma-enhanced chemical vapor deposition of vanadium pentoxide thin films from a vanadyl(IV) β-diketonate compound has been performed in a low-pressure reactor under different operating conditions. The effect of various parameters, such as the flow rates of the carrier and reactive gas and the substrate temperatures, on films composition, microstructure, and morphology was investigated in detail. Controlled variations of the synthesis conditions allowed a fine modulation of the sample properties, as shown by XRD and AFM analyses. In particular, at 200 °C and moderate oxygen flow, nanophasic V2O5 with a strong (001) preferential orientation could be easily obtained. The composition and purity of the films are studied by XPS and SIMS analyses, with special regard to film−substrate interdiffusion phenomena. Optical properties of the films are also investigated.

An η³-allylic complex of ruthenium(II) is used as a precursor for the chemical vapor deposition (CVD) of Ru and RuO2 thin films at low temperatures. The depositions are carried out on α-Al2O3 and surface-oxidized Si(100) in N2, N2 + H2, N2 + O2, or O2 flow to tailor the film composition from pure metal Ru to RuO2. The microstructure features of the samples are analyzed by X-ray diffraction and Raman spectroscopy, whereas their surface composition is studied by X-ray photoelectron spectroscopy. Surface and in-depth analyses of the coatings are also performed by secondary ion mass spectrometry, which allows to distinguish the composition of different coating regions along their thickness. The surface morphology and its dependence on the synthesis conditions are investigated by atomic force microscopy. The electrical and optical studies confirm the metallic character of Ru and RuO2 films.

The paper shows that, conceptually and operationally, the speed of light measured locally in the inertial comoving frame of a point on the rim of a rotating disk is different from the one measured globally for a round trip along the rim, obtained dividing the length of the rim (as measured in the “relative space” of the disk) by the time of flight of the light beam (as measured by a clock at rest on the disk). As a consequence, contrary to some recent claims, the anisotropy found in the global value, obtained by the above procedure, in no way conflicts with the local isotropy, and the internal consistency of the special relativity theory remains unchallenged.

Thin films of bismuth vanadates are deposited by chemical vapor deposition (CVD) on α-Al2O3 substrates using an O2 atmosphere and vanadyl(IV) acetylacetonate and triphenylbismuth as precursors. The microstructure of the samples is studied by XRD and Raman spectroscopy and their chemical composition is investigated by XPS and SIMS. AFM is used to analyze the surface morphology of the samples. All the samples show a nonohmic behavior beyond a threshold voltage, Vth, which is linearly dependent on the V⁴⁺/V⁵⁺ ratio. Impedance spectroscopy measurements indicate that the obtained samples are oxide ion conductors at room temperature and that the mechanism of ion conduction occurs by means of hopping between vacancies. Furthermore, ferroelectric−paraelectric transitions take place in the materials at low temperatures.

A procedure is given for the calculation of the weight function for a surface crack located in a thin surface layer perpendicular to the interface. The procedure is demonstrated for cracks approaching the interface and cracks going beyond the interface.

Eighteen patients bearing a hot nodule, imaged by basal 99Tcmscintiscan and toxic in eight of them, were studied.

Recent experimental data obtained by neutron spectrometry of zinc in several laboratories have been analysed with the purpose of producing the ion-ion potential in this liquid metal. The Percus-Yevick theory that is known to produce reliable inter-atomic potential in simple liquid insulators such as argon, as well as the hyperchain theory were used. Both theories are found to be inadequate in the case of liquid metals, at least if the experimental data presently available are used. Furthermore it seems that in order to proceed efficiently along this line, the region of low wave-vector transfer should be explored with much greater accuracy than now available both in X-ray and neutron-diffraction experiments. I dati sperimentali ottenuti recentemente in alcuni laboratori mediante diffrazione di neutroni lenti da zinco liquido sono stati analizzati allo scopo di determinare il potenziale ione-ione in tale metallo liquido. Sono state utilizzate sia la teoria « hyperchain ». sia la teoria di Percus-Yevick che dà buoni risultati per liquidi isolanti come l’argon. Entrambe le teorie si sono dimostrate inadeguate al caso di liquidi metallici, almeno quando vengono utilizzati i dati sperimentali attualmente disponibili. Al momento sembra che per ottenere risultati più attendibili sul potenziale ione-ione nei metalli liquidi occorra esplorare la regione di piccoli vettori d’onda trasferiti con accuratezza ben superiore a quella correntemente perseguibile in esperienze di diffrazione di raggi X e di neutroni. Были проаналиэированы недавние зкспериментальные данные, полученные посредством нейтронной спектроскопии жидкого цинка в нескольких лабораториях, с целью получения ион-ионного потенциала в зтом жидком металле. Испольэовались теория Перкуса-Йевика, которая, как покаэывается, дает надежный междуатомный потенциал в простом жидком иэоляторе, таком как аргон, а также и теория « гиперцепочки ». Найдено, что обе теории являются неадекватными в случае жидких металлов, по крайней мере, если испольэуются зкспериментальные данные, имеюшиеся в настояшее время. Кроме того, кажется, что для того, чтобы зффективно продолжать в зтом направлении, область с малой передачей волнового вектора должна быть исследована с больщей аккуратностью, чем в имеюшихся зкспериментах по диффракции нейтронов и рентгеновских лучей.

Ghigo E, Arvat E, Rizzi G, Goffi S, Grottoli S, Mucci M, Boghen MF, Camanni F. Growth hormonereleasing activity of growth hormone-releasing peptide-6 is maintained after short-term oral pretreatment with the hexapeptide in normal aging. Eur J Endocrinol 1994;131:499–503. ISSN 0804–4643The reduced activity of the growth hormone (GH)–insulin-like growth factor I (IGF-I) axis in aging may contribute to changes in body composition. As this GH insufficiency is due to hypothalamic pathogenesis, the availability of GH-releasing peptides (GHRPs), such as GHRP-6 (His-d-Trp-Ala-Trp-d-Phe-Lys-NH2) which is active even after oral administration, might be useful to restore it. The aim of our study was to verify the effectiveness of oral administration of GHRP-6 in normal elderly subjects and to investigate whether its GH-releasing activity is maintained or vanishes after short-term oral treatment. Seven normal elderly women (aged 65–82 years) were studied. The effect of oral administration of 300 μg/kg GHRP-6 on GH secretion was investigated before and after 4 days of treatment with the hexapeptide given twice daily. The GH response to the maximal effective dose of GHRH (1 μg/kg iv) also was studied. Before treatment, oral administration of 300 μg/kg GHRP-6 elicited a clear GH rise (peak 10.7 ± 3.3 μg/l; AUC 353.1 ± 90.6 μg·l−1·h−1). which was significantly higher (p < 0.01) than that induced by intravenous GHRH (peak 5.1 ± 1.5 μg/l; AUC 106.5 ±43.9 μg · l−1·h−1). After 4 days of treatment with GHRP-6, the GH response to the hexapeptide was maintained, with a trend towards an increase (peak 16.8 ± 2.9 μg/l; AUC 499.8 ± 107.2 μg·l−1·h−1). The IGF-I levels were not increased significantly after treatment (77.1 ± 8.4 vs 84.1 ± 12.2 μg/l). In conclusion, our results demonstrate that, in aging, oral GHRP-6 administration elicits a GH response that is higher than the maximal effective dose of intravenous GHRH and that the effect of the hexapeptide does not vanish after short-term treatment. More prolonged treatment and/or more frequent administrations of GHRP-6 are likely needed to increase IGF-I levels.F Camanni, Division of Endocrinology, Department of Pathophysiology, Ospedale Molinette, C.so Dogliotti 14, 10126 Torino, Italy

Sommario Nel presente lavoro è stato preso in considerazione il fenomeno di assorbimento-desorbimento cinetico quando un gas monocromatico urta una parete solida. Partendo da un modello della teoria cinetica dei gas recentemente proposto è stata determinata la probabilità di intrappolamento di particelle del fascio incidente sulla superficie stessa. Tale probabilità risulta essere funzione dell'energia e dell'angolo di incidenza e di alcuni parametri fenomenologici che tengono conto delle condizioni fisico-chimiche dell'accoppiamento gas-superficie. In tal senso è stata condotta un'analisi qualitativa di tale funzione, mostrando altresi come i parametri fenomenologici possano essere correlati a grandezze meccaniche direttamente misurabili. Infine i risultati della presente teoria sono stati confrontati con successo con alcuni recenti accurati risultati sperimentali.

This paper deals with two subjects concerning the analysis, design and tuning of joint position control loops. The first subject is the modelling of joint dynamics. Two linear models are derived: a second order rigid joint model and a fourth order one modelling the joint torsional flexibility. Model parameters are identified using data sequences obtained from open loop experiments performed on an assembly industrial manipulator. Comparisons between model and experimental results are given, to show to which extent the two models fit experimental data. The second subject concerns the dynamics of the resolver-to-digital tracking converter. The converter parameter tuning is discussed and the relevant transfer function is given.

In man the GH-releasing hexapeptide His-DTrp-Ala-Trp-DPhe-Lys-NH2 (GHRP-6) has been shown to be active even after oral administration. On the other hand, it has been shown that arginine (ARG) totally restores the reduced somatotropic responsiveness to GHRH observed in aging. Based on the foregoing, in this study we verified the GH-releasing activity of oral GHRP-6 (300 µg/kg) in normal aging and the possible enhancing effect of 8 g oral ARG on the GH-releasing effect of GHRP-6. Eight young (age 24–32 yr) and 8 elderly (age 66–85 yr) subjects were studied. In all the GH response to GHRH (1 µg/kg iv) was also studied. Both IGF-I levels and the GH response to iv GHRH were lower in elderly than in young subjects (mean±SE, IGF-I: 65.1±9.1 vs 142.9±9.4 µg/L, p<0.0001; GH peak: 5.4±1.0 vs 13.6 ± 0.8 µg/L, p<0.0001). Oral GHRP-6 administration induced a GH rise in elderly which was lower, though not significantly, than that in young subjects (GH peak: 9.9±2.0 vs 16.2±5.4 µg/L). Oral ARG administration enhanced the GHRP-6-induced GH rise in elderly (GH peak: 22.1±3.3 µg/L, p<0.01 vs GHRP-6 alone) while failed to modify it in young subjects (GH peak: 13.5±3.4 µg/L). The GH response to oral ARG+GHRP-6 in elderly was higher than that to all stimuli in young adults (p<0.05). In conclusion, present results show that in humans oral GHRP-6 administration induces a clear GH increase also in aging. The finding that ARG enhanced the activity of GHRP-6 in elderly but not in young subjects suggests that ARG is able to enhance the somatotropic responsiveness to GHRP-6 only when somatostatinergic activity is increased, i.e. in aging. Treatment with oral GHRP-6 alone or combined with low oral ARG may be hypothesized to restore GH secretion in aging.

If is often taken for granted that on a rotating disk it is possible to operate a global 3+1 splitting of spacetime such that both lengths and time intervals are uniquely defined in terms of measurements performed by real rods and real clocks at rest on the platform. This paper shows that this assumption, although widespread and apparently trivial, leads to an anisotropy of the velocity of two light beams traveling in opposite directions along the rim of the disk, which in turn implies some recently pointed out paradoxical consequences undermining the self-consistency of the special theory of relativity (SRT). A correct application of the SRT solves the problem and recovers complete internal consistency for the theory. As an immediate consequence, it is shown that the Sagnac effect only depends on the nonhomogeneity of time of the platform and has nothing to do with any anisotropy of the speed of light along the rim of the disk, contrary to an incorrect but widely held idea.

Ghigo E, Arvat E, Gianotti L, Grottoli S. Rizzi G, Ceda GP, Boghen MF, Deghenghi R, Camanni F. Shortterm administration of intranasal or oral Hexarelin, a synthetic hexapeptide. does not desensitize the growth hormone responsiveness in human aging. Eur J Endocrinol 1996;135:417–12. ISSN 0804–4643The function of the growth hormone–insulin-like growth factor I (GH–IGF-I) axis is reduced in aging, although the secretory capacity of somatotrope cells is preserved. Previous studies have suggested that continuous administration of GH-releasing peptides (GHRPs) results in homologous desensitization to the GH-releasing effect of the peptides. In the present study we have studied whether healthy elderly subjects would remain responsive to short-term, intermittent treatment with Hexarelin (HEX), a GHRP, and whether this treatment would result in an increase in serum IGF-I. In study I, the effect of an 8-day treatment with intranasal administration of 1.25 mg (about 18 μg/kg) t.i.d. HEX on the acute GH response to the hexapeptide and on serum IGF-I, IGF binding protein 3 (IGFBP-3), prolactin and cortisol levels was studied in seven elderly subjects (four males and three females, aged 67–80 years). In study II, the same parameters were studied before and after a 15-day treatment with oral administration of 20 mg (about 300 μg/kg) t.i.d. HEX in seven elderly women (aged 63–80 years). The GH response to the intranasal HEX administration was not significantly higher than that induced by 1 μg/kg iv GHRH (229.4± 35.9 vs 145.8 ± 26.9 μg·1−1·h−1) and was maintained with a trend towards increase after an 8-day treatment with the peptide (342.5 ± 199.3 μg·1−1·h−1). On the other hand, HEX treatment did not significantly modify IGF-I (138.7 ± 11.1 vs 122.4 ± 14.1 μg/l) but increased IGFBP-3 levels (2.4 ± 0.2 vs 1.6 ± 0.2 mg/l, p < 0.02). The GH response to the oral HEX administration was also not significantly higher than that to iv GHRH (257.6 ± 72.0 vs 179.0 ±42.8 μg·1−1·h−1) and did not change after a 15-day treatment with the peptide (237.8±42.8 μg·1−1·h−1). Both IGF-I and IGFBP-3 levels were slightly but significantly increased by oral HEX treatment (156.0 ± 10.7 vs 141.6 ± 13.6 μg/l. p< 0.03, 3.4 ±0.2 vs 3.1 ± 0.2 mg/l, p < 0.03, respectively). Neither intranasal nor oral HEX treatment modified PRL or cortisol levels and did not induce any side effect. In conclusion, these results indicate that chronic but intermittent treatment with HEX, administered either by intranasal or oral route, does not desensitize the GH response to the peptide. Moreover, after HEX treatment a trend towards increase was shown for IGF-I and IGFBP-3 levels. Thus, our findings strengthen the hypothesis that prolonged treatment with HEX may restore the reduced GH release in aging.F Camanni, Divisione di Endocrinologia. Ospedale Molinette. C. so Dogliotti 14, 10126 Torino. Italy

As is known, the expression of the electromagnetic field from a charge at rest on the symmetry axis of a Kerr spacetime, first given as a multi-polar expansion, has been later calculated in closed form. This allowed the derivation, in closed form, of the electromagnetic 4-potential and, consequently, the electrostatic self-interaction force (“self-force”) on the charge. We point out that, in order to derive the electromagnetic 4-potential and, consequently, the electrostatic self-force, a particular reference frame is required, in which the Kerr metric “locally” (i.e., in a small neighbourhood of the charge world-line) reduces to that of a static homogeneous gravitational field (SHGF). The starting point of this paper is the realization that the choice of such a reference frame in the literature is incorrect, because the phenomenon of dragging of inertial frames is neglected. This demands a new derivation both of the electromagnetic 4-potential and of the electrostatic self-force. To this end, we construct the correct reference frame, “locally“ transforming the Kerr metric into that of an SHGF. In such a frame, we derive the correct expressions both of the electromagnetic 4-potential and of the electrostatic self-force. In particular: i) the time component of the 4-potential differs from that known in the literature by an additional term, induced by the dragging of inertial frames, vanishing only on the symmetry axis; ii) the self-force turns out to be the sum of two terms, of which only the first (involving both the mass and the angular momentum per unit mass of the Kerr spacetime) is known in the literature. The second term (involving only the angular momentum per unit mass), which arises from a careful calculation and not from the additional term in the 4-potential, is a significant improvement provided by this paper.

As is known, a charge in a gravitational field experiences a (gravitationally-induced) self-interaction force (“self-force”) only in curved space-times (in any reference frame), but not in the accelerated frames in flat spacetimes. Therefore, the presence of any self-force indicates, from a formal point of view, a violation of the Strong Equivalence Principle (SEP); as a result, “observability of the self-force in the validity domain of classical electrodynamics” (CE) means “observability of the related violation of SEP”. In this paper we investigate the observability of the self-force on a charge at rest on the symmetry axis in a Kerr spacetime, as recently calculated in a paper by the same authors, in the validity domain of CE. Analysis shows that, in the validity domain of CE, no effect of the self-force is observable outside the Schwarzschild radius. In contrast, some effect is observable for very large values of the angular momentum, in a small neighbourhood of the “turning point” (where a reversal of the tidal forces direction takes place), between the outer horizon and the Schwarzschild radius. This is the only case we have found where SEP fails because of the self-force.

The profile of temperature, reagents, main reaction products, hydrocarbons and polycyclic aromatic hydrocarbons have been determined at different heights along a vertical flow reactor on which cool, blue and yellow flames of a n-heptane/oxygen/nitrogen mixture were stabilized at atmospheric pressureBecause of very large separation introduced by this vertical flow reactor in the different reaction stages and of suitable working conditions, several hydrocarbons - like vinylacetylene, benzene, toluene, xylenes, styrene, ethynylbenzene and methylnaphthalene - have been found in the blue and yellow flames by means of GC - MSThese hydrocarbons can be regarded as intermediate products in the formation of p.c.a.h. according to Badger's study in his pyrolysis experiments of several organic compoundFinally with this type of reactor it was possible to start the study of the deposition process of the polycyclic aromatic hydrocarbons and particularly of the potent carcinogens, like benz(a) anthracene and benz(a) pyrene by examining in which reactor zones, characterized by a given temperature range and by a particular soot morphology, they were collectedIt is our opinion that the physical and chemical considerations presented by this study can become very useful since much effort will have to be devoted in future to the problem of freeing the exhaust gases from polycyclic aromatic hydrocarbons.