1,720,983 research outputs found
La mappatura dei profili di competenza: una analisi comparata delle fonti
No full textRaccolta critica delle fonti sul degrado e gli interventi conservativi dei diversi tipi di materiali organici e inorganici utilizzati per il patrimonio culturale. Riflessione critica sulle competenze necessarie per una corretta conoscenza dei materiali stessi finalizzata all'individuazione delle loro tecniche di lavorazione e delle competenze necessarie per conservare, manutenere e restaurare i diversi materiali utilizzati per il patrimonio cultural
Spectroscopic comparison between poly[3-(6-methoxyhexyl)thiophene]s with different steric hindrance
No full textAn alternating methoxyhexylthiophene-thiophene copolymer was synthesized from 3-(6-methoxyhexyl)-2,2'-bithiophene and studied chiefly by means of optical absorption and nuclear magnetic resonance spectroscopy. The results were compared with those of the previously obtained poly[3-(6-methoxyhexyl)-2,5-thienylene]. The differences in the UV-Vis spectra of the two polymers in pure solvents, solvent/non-solvent mixtures and in films are discussed on the basis of the microstructure and the steric hindrance along the backbone. NMR spectroscopy revealed copolymer configuration to be regiorandom with a slight prevalence of head-to-head and tail-to-tail junctions. (C) 1999 Elsevier Science S.A. All rights reserved
EFFECTS OF HYPOTHYROIDISM AND ENDOCRINE DISRUPTOR-DEPENDENT NONTHYROIDAL ILLNESS SYNDROME ON THE GnRH-GONADOTROPHS AXIS OF THE MALE RAT
No full textABSTRACT. Effects of primary hypothyroidism (HYPO)
on the male gonadal axis are controversial, with only
scanty data on the gonadotroph cell response and no
information on GnRH tuberoinfundibular neurons,
even in animal models. HYPO has been reported to
variably induce hypogonadotropic hypogonadism, a
hypergonadotropic state, or to have no effects on
basal levels of pituitary gonadotropins, both in adult
male rats and humans. Similarly, the exogenous administration
of GnRH to HYPO rats and humans may
increase or decrease gonadotropin secretion. Since
inhibitory effects of HYPO on the GnRH-gonadotropin
axis are reversed by replacement with L-T4, it has
been suggested that thyroid hormone (TH) may regulate
tuberoinfundibular GnRH and pituitary gonadotropin
biosynthesis and/or secretion. To shed light on
this hypothesis, we conducted immunocytochemical
studies on the distribution and immunostaining
characteristics of hypophysiotropic GnRH neurons,
LH, PRL and vasoactive intestinal polypeptide (VIP)
immunoreactive (IR) cells in the pituitary of adult,
male rats. We show that HYPO reduces IR-GnRH in a
restricted population of tuberoinfundibular perikarya
and their proximal axons compared to euthyroid
controls, but increases IR-VIP both in pituitary cells in
direct association with LH-gonadotrophs and within
IR-LH cells, itself. We propose that VIP may serve as a
juxtacrine/paracrine/autocrine regulator of LH secretion
and that, when GnRH biosynthesis is reduced by
HYPO, gonadotropin secretion may be rescued by
local activating effects of VIP. Polychlorinated biphenyls
(PCB), industry toxicants found in food and water,
also have inhibitory effects on the gonadal axis,
decreasing fertility and suppressing basal and GnRHinduced
LH release in male rats. Since PCB may also
exert endocrine disruptor-dependent (EDD) effects
on the thyroid axis producing a non-thyroidal illness
syndrome (NTIS) (coined EDD-NTIS), we developed a
rat model of EDD-NTIS to determine whether central
hypothyroidism may contribute to the pathophysiology
of PCB-induced hypogonadism. On the basis of
preliminary animal data, we speculate that one of the
mechanisms for Partial Androgen Deficiency of the
Aging Male may involve central hypothyroidism and
EDD-NTIS, resulting in inhibition of the GnRH-gonadotroph
axis.J. Endocrinol. Invest. 28 (Suppl. to no. 11):20-27, 200
Characterization of a quasi-regiorandom poly[3-(6-methoxyhexyl)-2,2'-bithiophene]
No full textA quasi-regiorandom poly[3-(6-methoxyhexyl)-2,2'-bithiophene] was characterized through 1D and 2D 1H and 13C NMR spectroscopy
Effects of hypothyroidism and endocrine disruptor-dependent non-thyroidal illness syndrome on the GnRH-gonadotroph axis of the adult male rat
No full textEffects of primary hypothyroidism (HYPO) on the male gonadal axis are controversial, with only scanty data on the gonadotroph cell response and no information on GnRH tuberoinfundibular neurons, even in animal models. HYPO has been reported to variably induce hypogonadotropic hypogonadism, a hypergonadotropic state, or to have no effects on basal levels of pituitary gonadotropins, both in adult male rats and humans. Similarly, the exogenous administration of GnRH to HYPO rats and humans may increase or decrease gonadotropin secretion. Since inhibitory effects of HYPO on the GnRH-gonadotropin axis are reversed by replacement with L-T4, it has been suggested that thyroid hormone (TH) may regulate tuberoinfundibular GnRH and pituitary gonadotropin biosynthesis and/or secretion. To shed light on this hypothesis, we conducted immunocytochemical studies on the distribution and immunostaining characteristics of hypophysiotropic GnRH neurons, LH, PRL and vasoactive intestinal polypeptide (VIP) immunoreactive (IR) cells in the pituitary of adult, male rats. We show that HYPO reduces IR-GnRH in a restricted population of tuberoinfundibular perikarya and their proximal axons compared to euthyroid controls, but increases IR-VIP both in pituitary cells in direct association with LH-gonadotrophs and within IR-LH cells, itself. We propose that VIP may serve as a juxtacrine/paracrine/autocrine regulator of LH secretion and that, when GnRH biosynthesis is reduced by HYPO, gonadotropin secretion may be rescued by local activating effects of VIP. Polychlorinated biphenyls (PCB), industry toxicants found in food and water, also have inhibitory effects on the gonadal axis, decreasing fertility and suppressing basal and GnRHinduced LH release in male rats. Since PCB may also exert endocrine disruptor-dependent (EDD) effects on the thyroid axis producing a non-thyroidal illness syndrome (NTIS) (coined EDD-NTIS), we developed a rat model of EDD-NTIS to determine whether central hypothyroidism may contribute to the pathophysiology of PCB-induced hypogonadism. On the basis of preliminary animal data, we speculate that one of the mechanisms for Partial Androgen Deficiency of the Aging Male may involve central hypothyroidism and EDD-NTIS, resulting in inhibition of the GnRH-gonadotroph axis
Life Cycle Assessment of management systems for sewage sludge and food waste: centralized and decentralized approaches
No full textThe aim of the present study has been to assess the environmental profile of an experimental decentralized waste management system which is based on the anaerobic codigestion of the organic fraction of municipal solid waste (OFMSW) and dewatered sewage sludge in small plants (annual capacity: about 3000 t coupled at a 75 kW CHP unit) distributed over the territory. Two scenarios have been analysed: with and without aerobic composting post-treatment. In so far as an environmental point of view is concerned, such scenarios have been compared with the past and the current approaches occurring in the case study area (NE Italy) and characterized by a strong centralization. Environmental performances of the different scenarios have been assessed through Life Cycle Assessment methodology. Our results indicate that the anaerobic codigestion of dewatered sewage sludge and OFMSW in small plants combined with composting post-treatment may offer an environmentally sustainable option of waste management in small communities. This is achieved by (1) a strong reduction in the distances and volumes transported by road, (2) low energy requirement for the process itself, (3) energy saving from CHP unit and (4) energy/resources saving from the compost produced by the digested matter. Also social advantages may be gained, such as increased public acceptability of waste treatment facilities and increased awareness among citizen on waste management issue. To note that these advantages are closely related to some key assumptions like the use of digested matter as fertilizer. Assumptions and work limits are discussed in the final section of the paper
H-1 and C-13 NMR characterization of poly[3-(6-methoxyhexyl)-2,2 '-bithiophene]
No full textA full H-1 and C-1 NMR study through the use of one- and two-dimensional techniques (HMQC, HMBC, TOCSY and NOE-difference spectroscopy) was carried out on poly[3-(6-methoxyhexyl)-2,2 ́-bithiophene]. Inter-ring correlations detected in the HMBC spectra proved to be a valuable tool in the assignment of regiochemistry. NMR data can be interpreted on the basis of a four-triad model. Copyrigh
Distribuzione spaziale e variazioni stagionali dei popolamenti macrobentonici nella laguna costiera "Piallassa Baiona" (Ravenna)
No full textSono state investigate comunità macrobentoniche della laguna costiera "Piallassa Baiona" (Ravenna; Italia) in 10 siti e a tre date. Nel complesso sono stati rinvenuti 43 taxa. L'analisi dei dati mostra comunità tipiche di ambienti lagunari salmastri notoriamente condizionati da fluttuazioni giornaliere e stagionali dei parametri fisico-fisici; situazione che determina livelli di disturbo intermedio permanente, cui si somma l'effetto del confinamento e dei diversi fattori di impatto antropico. Ciò si riflette sulla diversità specifica, sui valori di biomassa e, almeno arzialmente, sui valori dell'indice biotico (BC)
13C Chemical Shifts: A Useful Tool for the Regiochemistry Assignment of Poly(3-Hexanoyloxyethyl-2,5-Thienylene)
No full textThe assignment of the regiochemistry of poly(3-hexanoyloxyethyl-2,5-thienylene) on the basis of the 13C chemical shifts of the configurational triads was reported
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