Evaluation and analysis of auditory function and its clinical characteristics in low birth weight premature infants / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate and analyze dynamic changes of auditory function in premature babies with fetal age of less than 37 weeks who were categorized into different birth weight groups and to detect abnormalities of auditory function in these babies and to describe the early development patterns of auditory function in infancy.</p><p><b>METHODS</b>Total of 252 subjects (504 ears) from neonatal ward, neonatal intensive care unit and auditory clinic in Guangzhou Children Hospital, whose fetal age were less than 37 weeks, were included in our study and received auditory function evaluation from January 2004 to February 2008. To investigate the correlation between birth weight and development and abnormality of auditory function in premature babies, all subjects were divided into four groups according to birth weight: </= 1.50 kg, 1.51 - 2.00 kg, 2.01 - 2.50 kg and > 2.5 kg. Each group was further categorized by subject's age on first auditory function evaluation in 0 - 3 months (include 3 months), 3 - 6 months (include 6 months) and above 6 months, respectively. Subjects who were evaluated more than once in different age frame would be grouped into multiple evaluation subgroups. All subjects underwent one or more objective auditory examinations including auditory brainstem response (ABR), distortion product otoacoustic emission (DPOAE), tympanometry and acoustic stapedius reflex.</p><p><b>RESULTS</b>A tendency of decreased wave V threshold of ABR was seen as birth weight increased, while the percentage of subjects with ABR wave V threshold </= 40 dB nHL increased as well. A tendency of decreased wave V threshold of ABR was also seen as age increased after birth, likewise the percentage of subjects with ABR wave V threshold </= 40 dB nHL increased with age after birth. For multiple evaluation subgroups, improvement rate ranged from 56.67% to 82.76% depending on subjects' birth weight. In all low birth weight (LBW) premature babies, 4 subjects and 6 ears with no wave or just wave V at maximum stimulation 103 dB nHL in ABR were diagnosed with auditory neuropathy, giving an incidence of 3.75%(by ears).</p><p><b>CONCLUSIONS</b>Auditory function (including middle ear and auditory nerve system) of premature LBW improved gradually within examined age frame, as birth weight and age after birth increased. For LBW preterm who showed abnormality in auditory evaluation, a 6-month follow-up should be scheduled, babies weighted less than 1.50 kg at birth that showed abnormality in the first auditory evaluation should be re-evaluated within 2 months. Babies weighted more than 1.50 kg who showed abnormality in the first auditory evaluation should be re-evaluated within 3 months.</p>

Thermochemical properties and non-isothermal decomposition reaction kinetics of 3,4-dinitrofurazanfuroxan (DNTF).

The constant-volume combustion energy, DeltacU (DNTF, s, 298.15K) and kinetic behavior of the exothermic decomposition reaction of the title compound (DNTF) are determined by a precise rotating bomb calorimeter and DSC, respectively. Its standard enthalpy of combustion, DeltacHmtheta (DNTF, s, 298.15K), standard enthalpy of formation, DeltacHmtheta (DNTF, s, 298.15K) and kinetic parameters of the major exothermic decomposition reaction in a temperature-programmed mode [the apparent activation energy (Ea) and pre-exponential factor (A)] are calculated. The values of DeltacU (DNTF, s, 298.15K), DeltacHmtheta (DNTF, s, 298.15K), and DeltacHmtheta (DNTF, s, 298.15K) of DNTF are -9733.96 +/- 8.59 Jg(-1), -3018.29 +/- 2.68 kJ mol(-1), and 657.23 +/- 2.70 kJ mol(-1), respectively. The kinetic model function in integral form and the value of E(a) and A of the major exothermic decomposition reaction of DNTF are 1-(1-alpha)1/3, 177.03 kJ mol(-1) and 10(13.68)s(-1), respectively. The critical temperature of thermal explosion of DNTF is 240.6 degrees C.

Kinetics and mechanism of the exothermic first-stage decomposition reaction of 1,3-bis(2,2,2-trinitroethyl)-1,3-diazacyclopentanone-2.

The thermal behavior, mechanism and kinetic parameters of the exothermic first-stage decomposition reaction of the title compound in a temperature-programmed mode have been investigated by means of DSC, TG-DTG and IR. The reaction mechanism was proposed. The kinetic model function in differential form, apparent activation energy (E(a)) and pre-exponential factor (A) of this reaction are (1-alpha)(2), 178.41 kJ mol(-1) and 10(17.06)s(-1), respectively. The critical temperature of thermal explosion of the compound is 184.99 degrees C. The values of DeltaS( not equal ), DeltaH( not equal ) and DeltaG( not equal ) of this reaction are 91.54 J mol(-1)K(-1), 176.86 kJ mol(-1) and 135.83 kJ mol(-1), respectively.