We examined the crystal and magnetic properties of the polymorphic LiFeO
2
compound using Mössbauer spectra (MS), X-ray diffraction data (XRD), and magnetic measurements. X-ray diffraction analysis ...of
α
-LiFeO
2
and
β
′
-LiFeO
2
phases reveals that short-range ordering observed in the
α
-LiFeO
2
phase is potentially linked to the
β
′
-LiFeO
2
phase nanoregions. Low-temperature MS of the
α
-LiFeO
2
phase reveal a complicated disordered magnetic state below 90 K. Rietveld analysis of the XRD data of the
γ
-LiFeO
2
phase reveals a defect microstructure. These defects produce a complicated distribution of the hyperfine magnetic field estimated from MS. While it is not possible to produce the
β
′
-LiFeO
2
phase in pure form, extended annealing of the
α
-LiFeO
2
phase at 400
∘
C yields a nanocomposite material comprising nanoregions of both
β
′
-LiFeO
2
and
γ
-LiFeO
2
phases.
Graphical abstract
The influence of aging on oral-pharyngeal swallowing was assessed by simultaneous manometry and videoradiography in 14 nondysphagic elderly individuals (mean age 76 yr) and 11 healthy, young controls ...(mean age 21 yr). Sphincter opening was diminished significantly in the elderly (P = 0.0001), but trans-sphincteric bolus flow rates were preserved. The increased impedance to trans-sphincteric bolus flow from reduced sphincter opening in the aged was reflected in a significant increase in hypopharyngeal intrabolus pressure (P = 0.003). Oral transit time was significantly prolonged in the aged (P = 0.01). The timing of upper esophageal sphincter (UES) manometric relaxation and of opening was significantly delayed in the aged (P = 0.0001), and this delay was comparable in magnitude to the prolongation in oral transit. Coordination of UES relaxation and opening with midpharyngeal contraction was not significantly affected by age. Deglutitive hyolaryngeal motion was not affected by age but was delayed by a duration equivalent to the prolongation in oral transit. We conclude that normal aging prolongs the oral-pharyngeal swallow that impairs UES opening but does not influence pharyngo-sphincteric coordination.
The aim of this study was to examine the relationship between colonic pressure waves and movement of content. In 11 healthy subjects, pressures were recorded at 10-cm intervals from cecum to rectum ...for 32 h. In six subjects, transit was simultaneously measured for 8 h after direct cecal instillation of 1.5 mCi of (99m)Tc sulfur colloid. Thirty-two percent of isotope movements were related to nonpropagating activity and twenty-eight percent to propagating sequences. The extent of isotope movement related to propagating sequences (25.1 +/- 2.1 cm) was greater than that due to nonpropagating activity (12.8 +/- 0.7 cm; P = 0.0001). Propagating sequences originated significantly more frequently (P = 0.004) and propagated further (P = 0.0006) in the proximal compared with the distal colon. Only 36% of propagating sequences were propulsive of content, and compared with nonpropulsive sequences, these propagated further (41 +/- 6 vs. 27 +/- 2 cm; P < 0.05) and had a higher probability of originating proximally (P = 0.0003), a higher pressure wave amplitude (50 +/- 5 vs. 34 +/- 4 mmHg; P = 0.0001), and slower velocity (2.2 +/- 0.3 vs. 3.6 +/- 0.47 cm/s; P = 0.02). We conclude that most movements of colonic content are related to pressure waves. There is marked regional variation in the prevalence, velocity, and extent of propagation of propagating pressure wave sequences, which are an important mechanism for transporting content over long distances. The effectiveness of transport by a propagating sequence is influenced by its site of origin, amplitude, and velocity.
