ABSTRACT
In this work pentose sugar (D-xylose, D-ribose and D-arabinose) gas phase dehydration reaction was investigated by means of mass spectrometric techniques and theoretical calculations. The ionic species derived from the dehydration reaction of protonated D-ribose and D-arabinose were structurally characterized by their fragmentation patterns and the relative dehydration energies measured by energy resolved CAD mass spectra. The results were compared with those recently obtained for D-xylose in the same mass spectrometric experimental conditions. Dehydration of C1-OH protonated sugars was theoretically investigated at the CCSD(T)/cc-pVTZ//M11/6-311++G(2d,2p) level of theory. Protonated pentoses are not stable and promptly lose a water molecule giving rise to the dehydrated ions at m/z 133. D-xylose, D-ribose and D-arabinose dehydration follows a common reaction pathway with ionic intermediates and transition states characterized by similar structures. Slightly different dehydration energies were experimentally measured and the relative trend was theoretically confirmed. The overall dehydration activation energy follows the order arabinoseâ¯<â¯riboseâ¯<â¯xylose. Gas-phase pentose sugar dehydration leads to the formation of protonated 2-furaldehyde as final product. Based on the experimental and theoretical evidence a new mechanistic hypothesis starting from C1-OH protonation was proposed.
Subject(s)
Arabinose/chemistry , Pentoses/chemistry , Ribose/chemistry , Sugars/chemistry , Xylose/chemistry , Dehydration , Mass SpectrometryABSTRACT
OBJECTIVES: Hearing loss is very common in our society, but epidemiological data on deafness in Italy is lacking. A.I.R.S. onlus (Italian Association for Research on Deafness) yearly launches the National Day for the Fight Against Deafness (NDFAD). During this events, that are held every year, it is possible to perform a free hearing test in all the facilities that have joined the initiative throughout Italy (240 hospitals joined in 2011). AIM: to report data collected throughout the "A.I.R.S. National Day for the Fight against Deafness" of the last years, focusing in particular but not only on audiometric outcomes. METHODS: demographic and social data, as well as audiometric outcomes, was collected on forms that have been subsequently stored in a on-line database and analyzed with MySQL and Microsoft Excel. CONCLUSIONS: This data are important in order to describe the "hearing health" of the Italian population, and is a first step towards creating a database with epidemiological and preventive aims, a strongly felt need both at national and at regional level.
Subject(s)
Hearing Loss/epidemiology , Adolescent , Adult , Audiometry, Pure-Tone , Child , Demography , Female , Humans , Italy/epidemiology , Male , Middle Aged , Occupations , Young AdultABSTRACT
This study was performed to assess the effectiveness of ultrasonography in the diagnosis of wrist ganglia and in their differentiation from other lesions. Sonographic examination of 73 patients with palpable masses was performed; their healthy hands and those of 25 healthy volunteers constituted the reference standard. Ganglia appeared sonographically as anechoic oval, round, or lobulated cystic structures. Ultrasound proved an accurate tool in their diagnosis, with the general advantages of easy, quick, and inexpensive application.
Subject(s)
Synovial Cyst/diagnostic imaging , Wrist/diagnostic imaging , Adolescent , Adult , Biopsy, Needle , Carpal Bones/diagnostic imaging , Diagnosis, Differential , Female , Hand/diagnostic imaging , Humans , Male , Middle Aged , Ultrasonography, InterventionalABSTRACT
PIP: The author discusses two categories of demographic measurement that can be used to study the distinguishing characteristics of a country's foreign population. The first category pertains to data that can be obtained from censuses concerning structural characteristics such as age, marital status, legitimacy, infant mortality, and place of birth. The second category concerns data that can be derived from various other sources and includes such items as life expectancy and general fertility rate. The author also examines the usefulness of these methods for studying the foreign population in Italy given experiences with the methods used in other countries.^ieng
