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1.
Injury ; 54 Suppl 1: S2-S8, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33757663

RESUMO

INTRODUCTION: Humeral shaft fractures represent about 3% of all fractures. While there are several treatment options for this type of fractures, there is no evidence in literature showing which is the best one. This study aims at analysing the outcomes for patients with humeral shaft fractures treated with Locking Compression Plate (LCP) fixation in our hospital and comparing them with the outcome for patients conservatively treated (according to data from Pubmed),in order to determine the best treatment option. MATERIALS AND METHODS: We treated surgically 220 humeral shaft fractures in our department from February 2005 to March 2012. Seventy-three of them met all the inclusion criteria for this study. All fractures were then classified according to the AO classification. The follow-up considered the radiographic healing of the fracture. All patients were treated with plate fixation (LCP - DePuySynthes Co). At the end of the four-year follow-up, the function was evaluated by means of the DASH score. A systematic review of the literature of the last 20 years was performed on MEDLINE (PubMed). RESULTS: We had 2 infections and 8 patients had postoperative nerve palsy which recovered in average time of 6.7 months. In addition, 4 fractures (5.48%) didn't heal within 6 months and they were considered as nonunions and healed after a second surgery. One of these 4 nonunions was infected. The mean DASH score was 18.24±19.18. No malunions were found. We identified 13 studies that were eligible for our systematic review. The mean non-union rate found was 17% in 2517 fractures with a follow-up that ranging from 67% to 100% of patients and a primary radial nerve palsy ranging from 0 to 115 patients. Malalignment rate ranged from 12.7 to 42%. CONCLUSIONS: After taking into account both the conservative and the surgical treatment, for humeral shaft fractures we suggest the operative treatment, because the patient's function of the upper limb recovers quickly in the immediate postoperative period and the incidence of malunions may be avoided.


Assuntos
Tratamento Conservador , Fraturas do Úmero , Humanos , Fraturas do Úmero/diagnóstico por imagem , Fraturas do Úmero/cirurgia , Úmero , Placas Ósseas , Diáfises
2.
J Biol Regul Homeost Agents ; 34(4 Suppl. 3): 231-236. Congress of the Italian Orthopaedic Research Society, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33261283

RESUMO

Management of blast injuries with open fractures and extensive soft tissue damage in pediatric patients is a challenging task even in experienced hands. This article reports the case of an 8-year-old boy with bilateral open tibia fractures and soft tissue loss due to the accidental explosion of a skyrocket. After the emergency procedures with lavage, debridement and temporary bone stabilization, we performed the definitive reconstruction surgery using a combined circular external fixation and flexible intramedullary nailing technique on both legs. This technique allowed easy access to the wounds for plastic surgery procedures and early bilateral weight bearing. All implants were removed within 6 months, the fractures healed with good axial alignment and the patient returned to his preinjury activities one year after the trauma. In this case, the combined use of circular external fixation and flexible intramedullary nailing ensured optimal fractures stabilization, minimizing the damage to the soft tissues and the obstruction for plastic surgeons. We believe that this technique should be considered in pediatric patients with open fractures of the lower limbs and extensive soft tissue injuries.


Assuntos
Traumatismos por Explosões , Fixação Intramedular de Fraturas , Fraturas da Tíbia , Traumatismos por Explosões/cirurgia , Criança , Fixadores Externos , Fixação de Fratura , Consolidação da Fratura , Humanos , Masculino , Tíbia , Fraturas da Tíbia/diagnóstico por imagem , Fraturas da Tíbia/cirurgia , Resultado do Tratamento
4.
Neurol Sci ; 37(10): 1713-21, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27395388

RESUMO

Cognitive deficits occur in most stroke patients and cognitive impairment is an important predictor of adverse long term outcome. However, current screening measures, such as the Mini Mental State Examination or the Montreal Cognitive Assessment, do not provide information tuned for evaluating the impact of cognitive impairment in the early phase after stroke. The Oxford Cognitive Screen (OCS) represents an important new development in this regard. The OCS is now available for assessment of Italian individuals and the aim of this study is to standardize the OCS on a large sample of healthy Italian participants stratified for age, gender and education level. Results confirmed the influence of these factors in several of the OCS tasks. Age-, education- and gender-adjusted norms are provided for the ten sub-tests of the test. The availability of normative data represents an important prerequite for the reliable use of OCS with stroke patients.


Assuntos
Transtornos Cognitivos/diagnóstico , Transtornos Cognitivos/etiologia , Testes Neuropsicológicos , Acidente Vascular Cerebral/complicações , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Atenção , Cognição , Feminino , Humanos , Itália , Idioma , Masculino , Entrevista Psiquiátrica Padronizada , Pessoa de Meia-Idade , Valores de Referência , Tradução , Adulto Jovem
5.
Neurol Sci ; 36(7): 1233-40, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25618236

RESUMO

Hemispatial neglect due to right parieto-temporo-frontal lesions has a negative impact on the success of rehabilitation, resulting in poor functional gain. Recent research has shown that different types of neglect can impact in a different way on rehabilitation outcomes. The availability of a sensitive test, useful for distinguishing egocentric and allocentric forms of neglect, may be clinically important as all current clinical instruments fail to distinguish between these forms of disturbance, yet they differentially predict outcome. The Apples Test is a new instrument useful to evaluate both egocentric and allocentric forms of neglect. In order to establish Italian norms for this diagnostic instrument the test was administered to a sample of 412 healthy people of both genders (201 M and 211 F), aged from 20 to 80 years enrolled from 14 different rehabilitation centers in Italy. Based on the data, we established pathological performance cut-offs for the accuracy score (total omission errors), the asymmetry score for egocentric neglect (omission error difference), the asymmetry score for allocentric neglect (commission error difference) and execution time. The usefulness of the Apples Test for diagnostic purposes is illustrated by presenting three patients with different forms of neglect (egocentric, allocentric and mixed neglect).


Assuntos
Atenção/fisiologia , Lateralidade Funcional/fisiologia , Desempenho Psicomotor/fisiologia , Percepção Espacial/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Escolaridade , Feminino , Humanos , Itália , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Transtornos da Percepção/diagnóstico , Valores de Referência , Campos Visuais/fisiologia , Adulto Jovem
6.
Artigo em Inglês | MEDLINE | ID: mdl-24765877

RESUMO

OBJECTIVES: In this multicenter survey, we assessed the impact of sensitization to cypress in atopic patients in Italy and determined whether cypress pollen concentration changed over time. METHODS: Allergists were required to collect the results of 100-200 consecutive skin prick tests (SPTs) performed during 2012. Seasonal symptoms were also recorded, as were airborne cypress pollen concentrations (data from the Italian Aerobiology Association) in 1998-2000 and 2010-2012. RESULTS: We examined 2258 atopic outpatients (56% females; age, 2-84 years) sensitized to at least 1 of the aeroallergens tested (Dermatophagoides species, grass, pellitory, olive, cypress, birch, Alternaria tenuis, and dog and cat dander). We found that 62.9%, 16.1%, and 32.7% of patients living in central, northern, and southern Italy, respectively, were sensitized to cypress (P < .0001). The cypress pollen concentration peak was delayed from February to March in 1998-2000 and 2010-2012 in all 3 regions, with a shift in pollination towards spring. Patients who were monosensitized to cypress reported mainly rhinitis (90.7%-97.6%) and conjunctivitis (38.1%-100%). In polysensitized patients, the prevalence of rhinitis, conjunctivitis, and asthma increased progressively (P < .0001) from southern to northern Italy. The same trend was observed for the prevalence of reported winter symptoms typical of cypress allergy (28%-65%). CONCLUSIONS: Today, cypress pollen is the most frequent sensitizing aeroallergen (assessed by SPT) in several areas of central Italy. Variations in the timing of the cypress pollination period may have favored this increased sensitization. Rhinitis and conjunctivitis are the predominant symptoms. The clinical impact of this allergy was poor in southern Italy and increased in central areas before reaching its peak in northern regions.


Assuntos
Alérgenos/imunologia , Cupressus/imunologia , Hipersensibilidade Imediata/epidemiologia , Hipersensibilidade Imediata/imunologia , Hipersensibilidade/epidemiologia , Hipersensibilidade/imunologia , Pólen/imunologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Feminino , Humanos , Itália/epidemiologia , Masculino , Pessoa de Meia-Idade , Adulto Jovem
7.
J. investig. allergol. clin. immunol ; 24(1): 23-28, ene.-feb. 2014. tab, ilus
Artigo em Inglês | IBECS | ID: ibc-119150

RESUMO

Objectives: In this multicenter survey, we assessed the impact of sensitization to cypress in atopic patients in Italy and determined whether cypress pollen concentration changed over time. Methods: Allergists were required to collect the results of 100-200 consecutive skin prick tests (SPTs) performed during 2012. Seasonal symptoms were also recorded, as were airborne cypress pollen concentrations (data from the Italian Aerobiology Association) in 1998- 2000 and 2010-2012. Results: We examined 2258 atopic outpatients (56% females; age, 2-84 years) sensitized to at least 1 of the aeroallergens tested (Dermatophagoides species, grass, pellitory, olive, cypress, birch, Alternaria tenuis, and dog and cat dander). We found that 62.9%, 16.1%, and 32.7% of patients living in central, northern, and southern Italy, respectively, were sensitized to cypress (P<.0001). The cypress pollen concentration peak was delayed from February to March in 1998-2000 and 2010-2012 in all 3 regions, with a shift in pollination towards spring. Patients who were monosensitized to cypress reported mainly rhinitis (90.7%-97.6%) and conjunctivitis (38.1%-100%). In polysensitized patients, the prevalence of rhinitis, conjunctivitis, and asthma increased progressively (P<.0001) from southern to northern Italy. The same trend was observed for the prevalence of reported winter symptoms typical of cypress allergy (28%-65%). Conclusions: Today, cypress pollen is the most frequent sensitizing aeroallergen (assessed by SPT) in several areas of central Italy. Variations in the timing of the cypress pollination period may have favored this increased sensitization. Rhinitis and conjunctivitis are the predominant symptoms. The clinical impact of this allergy was poor in southern Italy and increased in central areas before reaching its peak in northern regions (AU)


Antecedentes: Se trata de una encuesta multicéntrica realizada en Italia para evaluar el impacto de la sensibilización a polen de ciprés en sujetos atópicos y establecer si la concentración de este polen en el aire ha cambiado a lo largo del tiempo. Métodos: El estudio fue realizado por alergólogos que recopilaron 100-200 sujetos consecutivos con pruebas cutáneas positivas (Prick) realizadas en 2012. Se recogieron los síntomas estacionales, junto con la concentración de polen de ciprés (obtenida por la asociación italiana de aerobiología) en 1998-2000 y 2010-2012. Resultados: En cuanto a los resultados obtenidos fueron examinados 2258 pacientes atópicos (56% mujeres; edad 2-84), sensibilizados frente al menos uno de los aeroalérgenos testados (Dermatophagoides, gramíneas, parietaria, olivo, cipres, abedul, Alternaria tenuis y epitelio de gato). El 62.9%, 16.1% y 32.7% de los pacientes que vivían en el centro, norte y sur de Italia, respectivamente, mostraron sensibilización a polen de ciprés (p<0.0001). Observamos un pico de concentración de polen de ciprés de febrero a marzo en los años 1998-2000 y 2010-2012, en todas las áreas. Los pacientes monosensibilizados a ciprés mostraron de forma prevalente rinitis (90.7-97.6%) y conjuntivitis (38.1-100%). La prevalencia de rinitis, conjuntivitis y asma se incrementa progresivamente (p<0.0001) del sur hacia el norte de Italia en los sujetos polisensibilizados. La misma tendencia se observó en los síntomas invernales típicos de la alergia al ciprés. Conclusiones: En conclusión, actualmente el polen de ciprés es el aeroalérgeno sensibilizante más frecuente (según resultados de prueba cutánea) en varias áreas de Italia central. Las variaciones del periodo de polinización pueden favorecer el incremento observado en la sensibilización a este polen. Los síntomas predominantes son rinitis y conjuntivitis. El impacto clínico de esta alergia es pobre en áreas del sur de Italia, siendo alto en las áreas del norte (AU)


Assuntos
Humanos , Cupressus , Pólen/efeitos adversos , Rinite Alérgica Sazonal/epidemiologia , Antígenos de Plantas/isolamento & purificação , Anafilaxia/epidemiologia , Itália , Testes Cutâneos , Inquéritos Epidemiológicos
8.
Eur J Phys Rehabil Med ; 48(2): 197-208, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22318363

RESUMO

BACKGROUND: Many studies reveal that neglect is a major cause of disability in stroke patients, and two months from onset neglect is still present in approximately 50% of individuals with a right brain lesion. Among the various methods of neglect rehabilitation, we have turned our attention to the prism adaptation treatment, developed by Rossetti in 1998. This treatment uses prismatic lenses, which produce a deviation of the fixation point of the visual field of 10 degrees to the right, 5 degrees below the coordinates of reference resulting from neglect. AIM: To set out the possible effectiveness of less powerful lenses, we studied the response of a group of neglect patients treated with prismatic lenses that produce a deviation of the fixation point of only 5 degrees to the right, comparing them with a group of patients receiving placebo lenses. DESIGN: Randomized controlled trial. SETTING: Outpatients. POPULATION: The study involved 29 patients with left visual neglect. METHODS: All patients were assessed with a battery of seven visual-spatial tests. All patients were randomized by the pilot center and assigned to two different groups: "A" treated with pointing exercises and prismatic lenses of 5° to the right; "B" treated with pointing exercises and neutral lenses. Each group was treated with 5 rehabilitation sessions, lasting about 30 minutes each, from Monday to Friday for one week in the morning, by the same investigator, in each center. CONCLUSION: The results showed that the prismatic lenses of only five degrees, used for the study, did not contribute to the variation in performance. Thus, this deviation of the fixation point of the visual field to the right is not sufficient to create a therapeutic effect. The improvement observed within the two groups, seems likely to be correlated with the pointing exercises, which force the subject to perform a visuomotor task with the healthy arm also in the neglected side. CLINICAL REHABILITATION IMPACT: We believe that in order to carry out an effective treatment with prismatic lenses they must have a grade of at least 20 prism diopters. Lower grades are unable to determine an effect. Finally, because of the severe impact of neglect on the work of the rehabilitation team, and since our data shows that only five sessions are sufficient to demonstrate a change in performance, we believe that it is appropriate to use this method, especially in the acute phase of the disease.


Assuntos
Adaptação Fisiológica/fisiologia , Lentes , Transtornos da Percepção/reabilitação , Desempenho Psicomotor/fisiologia , Reabilitação do Acidente Vascular Cerebral , Idoso , Idoso de 80 Anos ou mais , Atenção/fisiologia , Córtex Cerebral/fisiopatologia , Feminino , Seguimentos , Lateralidade Funcional , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Orientação/fisiologia , Transtornos da Percepção/etiologia , Transtornos da Percepção/fisiopatologia , Prognóstico , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/fisiopatologia
9.
Carbohydr Polym ; 87(1): 265-273, 2012 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-34662960

RESUMO

This paper presents a detailed analysis of effect induced by a dry ball milling process on cellulose structure, morphology and properties. The partial amorphization of cellulose was qualitatively estimated by ATR-FTIR analysis. Through WAXD analysis the crystallinity index and the mean size of the cellulose crystallite domains were calculated, both these parameters showing a progressive decrease as a function of the milling time. In particular, crystallinity index decreased from 0.53 to 0.15 after 60min ball milling, whereas the mean size of the cellulose crystallite domains showed a reduction from the original value of about 4.0nm up to about 3.4nm after 30min. These quantitative results were confirmed by 13C CP-MAS NMR analysis and measurements of the proton spin-lattice relaxation time in the rotating frame (T1ρ1H). Moreover, the increasing of the amount of water absorbed by cellulose samples (from 7.3wt% for untreated cellulose up to 11.6wt% for the cellulose sample ball milled for 60min) and the reduction of the thermal stability were evaluated by TGA. Finally, SEM analysis revealed that the original fibrous structure almost disappeared and was modified to a quasi-circular shape.

10.
Talanta ; 82(5): 1826-38, 2010 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-20875584

RESUMO

The metabolic profiling of kiwifruit (Actinidia deliciosa, Hayward cultivar) aqueous extracts and the water status of entire kiwifruits were monitored over the season (June-December) using nuclear magnetic resonance (NMR) methodologies. The metabolic profiling of aqueous kiwifruit extracts was investigated by means of high field NMR spectroscopy. A large number of water-soluble metabolites were assigned by means of 1D and 2D NMR experiments. The change in the metabolic profiles monitored over the season allowed the kiwifruit development to be investigated. Specific temporal trends of aminoacids, sugars, organic acids and other metabolites were observed. The water status of kiwifruits was monitored directly on the intact fruit measuring the T(2) spin-spin relaxation time by means of a portable unilateral NMR instrument, fully non-invasive. Again, clear trends of the relaxation time were observed during the monitoring period. The results show that the monitoring of the metabolic profiling and the monitoring of the water status are two complementary means suitable to have a complete view of the investigated fruit.


Assuntos
Actinidia/metabolismo , Análise de Alimentos/métodos , Frutas/química , Espectroscopia de Ressonância Magnética/métodos , Água/análise , Actinidia/crescimento & desenvolvimento , Aminoácidos/análise , Carboidratos/análise , Ácidos Carboxílicos/análise , Frutas/crescimento & desenvolvimento , Frutas/metabolismo , Itália , Extratos Vegetais/química , Estações do Ano
11.
Talanta ; 80(5): 2141-8, 2010 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-20152464

RESUMO

An NMR and chemometric analytical approach to classify extra virgin olive oils according to their geographical origin was developed within the European TRACE project (FP6-2003-FOOD-2-A, contract number: 0060942). Olive oils (896 samples) of three consecutive harvesting years (2005, 2006, and 2007) coming from Mediterranean areas were analyzed by (1)H NMR spectroscopy. Olive oil samples from Liguria, an Italian region, were chosen as a case study and PLS-DA and SIMCA modeling analyses were used to build up statistical models both to discriminate between Ligurian and non-Ligurian olive oils and to define the Ligurian olive oil class to confirm the declared provenience.


Assuntos
Espectroscopia de Ressonância Magnética/métodos , Óleos de Plantas/classificação , Europa (Continente) , Análise dos Mínimos Quadrados , Azeite de Oliva , Óleos de Plantas/análise
12.
Strategies Trauma Limb Reconstr ; 4(1): 1-6, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19296203

RESUMO

The treatment of tibial plafond fractures requires careful management of the soft tissue envelope, reconstruction of the articular surface and stable fixation with minimal additional damage. Thirty cases of AO type 43 C tibial fractures were treated by transosseous osteosynthesis (Ilizarov technique). The external fixator constructs used were Ilizarov (Transosseous osteosynthesis: theoretical and clinical aspects of the regeneration and growth of tissue, Springer, Berlin, 1992) and Sheffield (Classification AO des fractures, Springer, Berlin, 1987) circular fixator systems. All tibial plafond fractures healed. Using radiological criteria for assessment of reduction of the articular fragments and the clinical scoring system described by Teeny and Wiss, there were excellent and good restoration of articular structure in 27 cases and good clinical results in 14. This treatment method compares well with previous published series and is to be recommended for this group of difficult fractures.

13.
Talanta ; 77(1): 433-44, 2008 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-18804657

RESUMO

The nuclear magnetic resonance (NMR) technique was used as analytical tool to determine the complete metabolic profiling of sea bass extracts: water-soluble metabolites belonging to different classes such as sugars, amino acids, dipeptides and organic acids as well as metabolites soluble in organic solvent such as lipids, sterols and fatty acids were identified. The metabolite profiling together with a suitable statistical analysis were used to discriminate between wild and cultured sea bass samples. Preliminary results show that discrimination between wild and cultured sea bass was obtained not only using fatty acid composition but also cholesterol and phosphatidylethanolamine and some water-soluble metabolites such as choline, trimethylamine oxide, glutamine, fumaric and malic acids.


Assuntos
Bass/metabolismo , Pesqueiros , Espectroscopia de Ressonância Magnética/métodos , Extratos de Tecidos/química , Aminoácidos/metabolismo , Animais , Metabolismo dos Carboidratos , Metabolismo dos Lipídeos , Peptídeos/metabolismo
14.
Anal Chim Acta ; 623(2): 187-94, 2008 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-18620923

RESUMO

A Dutch map from the eighteenth century was multi-analytically analysed making use of energy dispersive X-ray fluorescence (EDXRF), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), Raman and scanning electron microscopy coupled to energy dispersive spectrometry (SEM-EDS). The cellulosic support was characterised and its state of conservation was evaluated. Besides, paramagnetic impurities were detected together with copper metallic chips. The colours present in some areas of the map were also analysed. Vermilion, carbon black and organic pigments were found. Surprisingly, in the green areas, the rare presence of the mineral moolooite (copper oxalate) was detected. A possible biological attack is discussed in order to explain the presence of such compound. Almost all of the techniques used in the analysis were portable, non-destructive and non-invasive, which is very desirable when analysing objects belonging to Cultural Heritage. The need for a multi-analytical approach using portable instrumentation is also discussed.

15.
Anal Bioanal Chem ; 391(1): 433-41, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18373086

RESUMO

A complete multianalytical study of a hand-coloured map from the seventeenth century is presented. The pigments atacamite, massicot, minium, gypsum, carbon black and vermilion were determined by means of XRF and Raman spectroscopy. The state of conservation of the cellulosic support was monitored by means of unilateral NMR. The analysis was nondestructive and noninvasive, and thus several spectra were collected from the same areas, yielding more reliable results without damaging the artwork. The role of copper pigments in the oxidation processes observed in the cellulosic support is discussed, as well as the possible provenance of atacamite as a raw material instead of as a degradation product of malachite.

16.
J Magn Reson ; 186(2): 311-8, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17433740

RESUMO

Wall paintings in the XVI century Serra Chapel in the "Chiesa di Nostra Signora del Sacro Cuore" Rome, have been studied using unilateral NMR. In order to map the distribution of moisture content in the wall painted, a large number of Hahn echo measurements, covering large areas of the wall painting were performed. Because the intensity of the Hahn echo is proportional to the amount of moisture in the area under study, the experimental data were transformed into 2D gradient colour maps which allowed an easy visualization of the moisture content of the wall. The state of conservation of the wall painting was monitored using T2 measurements specially with regards to outcropping salt.


Assuntos
Espectroscopia de Ressonância Magnética/métodos , Pinturas , História do Século XVI , Itália , Sais
17.
J Magn Reson ; 177(1): 111-7, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16115786

RESUMO

Unilateral NMR has been used to monitor the state of conservation of frescoes in the Vasari's house in Florence. The causes of deterioration of ancient frescoes are varied, which result in the detachment and crumbling of the painted film from the supporting plaster and in the outcropping of salts. Unilateral measurements of Hahn echo performed on such frescoes have allowed a perfect identification of the detachment of the painted film from the plaster. The presence of soluble salts on the pictorial film affects the spin-spin relaxation times, T(2). It is then possible using this technique, to characterize the effect of chemical treatments, of cleansing and consolidation procedures using the distribution of T(2) spin-spin relaxation times.

18.
J Magn Reson ; 170(1): 113-20, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15324764

RESUMO

High quality paper samples have been oxidized with a specific oxidant to reproduce one of the possible causes of the aging of paper. All samples have been characterized by 13C CP-MAS NMR spectroscopy. The artificial aging of paper has been monitored using a standard NMR relaxometer and the results have been compared with the corresponding data obtained using an unilateral NMR relaxometer. Experimental values obtained with both techniques are in agreement, demonstrating that unilateral NMR relaxometric measurements constitute a suitable non-invasive method for assessing the degradation process of cellulose-based materials. The sensitivity of the non-invasive NMR method allows the detection of degradation even at a very early stage. Effects due to the sample volume and to the penetration depth have been investigated.

19.
J Magn Reson ; 150(2): 178-83, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11384178

RESUMO

Magnetic multipoles of rank higher than one become active in spin systems with I > 1/2 and their contribution to relaxation depends on dynamics. The appearance of multipole terms complicates the relaxation description and supports the multiexponential behavior of relaxation. In this paper the effects of high-rank multipoles on lineshape and longitudinal relaxation of I = 3 spin systems are presented. Results obtained from both numerical simulation and experimental data show that longitudinal and transverse relaxation are strongly influenced by these multipole terms, especially at lower temperature where, due to lower molecular mobility, the extreme narrowing condition is not fulfilled.

20.
Biomacromolecules ; 1(2): 259-67, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-11710109

RESUMO

Original data are provided demonstrating that the title condensations are simple and versatile methods for the synthesis of hydrogels based on a variety of carboxylated polysaccharides. In this work, the biopolymers considered are sodium hyaluronate and sodium alginate. Nonnatural carboxylated polysaccharides were commercial (carboxymethyl)cellulose or were obtained by carboxymethylation or selective oxidation of primary alcohol groups of scleroglucan and dextran. Hydrogels prepared via the Passerini reaction were transparent, alkali labile materials whereas the transparency of the Ugi gels depended on the polysaccharide, the cross-linker, and the degree of cross-linking. The Ugi gels were stable for several months at a pH ranging from 1.3 to 11 and up to temperatures over 90 degrees C. The structure of the networks was studied by means of 13C CP-MAS and 15N CP-MAS NMR spectroscopy. A quantitative NMR analysis and elemental analysis of the dry gels allowed us to estimate the efficiency of the reactions, i.e., the actual degree of cross-linking, which appeared to be about 80% of theoretical. The influence of added salt and pH on the swelling of several Ugi gels with different degrees of cross-linking was studied in a qualitative manner.


Assuntos
Hidrogéis/química , Polissacarídeos/química , Sequência de Carboidratos , Reagentes de Ligações Cruzadas , Hidrogéis/síntese química , Concentração de Íons de Hidrogênio , Indicadores e Reagentes , Espectroscopia de Ressonância Magnética , Metilação , Dados de Sequência Molecular , Oxirredução , Polissacarídeos/síntese química
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