Mean Lateral Diameter Research Articles

The Cologne rebubbling study: a reappraisal of 624 rebubblings after Descemet membrane endothelial keratoplasty

Background/AimsTo analyse graft detachments prior to rebubbling, the influence of rebubbling on the postoperative outcome after Descemet membrane endothelial keratoplasty (DMEK) and the need for rebubbling on the contralateral eye.MethodsIn...

Anatomical Variations and Morphometric Features of the Foramen Transversarium in the Cervical Vertebrae of a Latin American Population: A Brazilian Study

Knowledge of the anatomy of the foramen transversarium (FT) is essential for performing surgical procedures on the cervical spine. The aim of the present study was to analyze the characteristics of the FT anatomy of the lower cervical spine and its anatomic variations using computed tomography (CT) in a Brazilian population. Two independent observers performed linear measurements of the anteroposterior diameter (APD), lateral diameter (LD), and FT area (FTA) of 600 FTs of the lower cervical spine of 60 individuals (30 women and 30 men). The CT images were obtained from a database. The data were compared between genders and different age cohorts. The lowest average APD, LD, and FTA were found at the C7 level. The highest mean APD was found at the C6 level, and the highest mean LD was found at the C3 level. The highest mean FTA was at the C3 for the women and C6 for the men. The mean APD, LD, and FTA on the left side were greater than those on the right side at all levels. We found a tendency for the mean FTA to increase with increasing age. Finally, 95% of the whole sample had presented with ≥1 and 42% with >3 anatomical variations of the FT. We determined the morphometric features of the FT using CT images. Anatomic variations were observed that justify their study before performing cervical surgical procedures.

Functional MoS2 nanosheets for precursor and mature microRNA detection in living cells.

Mature microRNAs (miRNAs) are small-sized RNAs cleaved from precursor microRNAs (pre-miRNAs) by the RNase Dicer. Various miRNAs play key regulatory roles in tumorigenesis and metastasis, and are therefore potential diagnostic and prognostic cancer biomarkers. However, detecting miRNAs and pre-miRNAs accurately and selectively in living cells remains a major challenge, as the mature miRNA sequence is also present in its pre-miRNA and current sequence probes exhibit poor gene delivery efficiency. Herein, we report a strategy for selectively and accurately detecting miRNA-21 and pre-miRNA-21 in living cells using functional MoS2 nanosheets (NSs) loaded with rationally engineered molecular beacons (MBs). The exfoliated MoS2 nanosheets (NSs) with a mean lateral diameter of 50-70nm were functionalized with the aptamer AS1411 and polyethylene glycol (MoS2-PEG-AS) to achieve target-cell-specific delivery and to enhance biocompatibility. The large available surface of the MoS2-PEG-AS was loaded with MB probes. The resulting MoS2-PEG-AS/MBs present cancer-cell-targeting ability, good protection properties, good optical stability, and biocompatibility. We demonstrated that the resulting nanoprobes can selectively image miRNA-21 and pre-miRNA-21 in various cell lines by facilitating enhanced fluorescence in the presence of miRNA-21 and pre-miRNA-21. Thus, these MoS2-PEG-AS/MBs are potentially a tool to discriminate between intracellular miRNA and pre-miRNA at different expression levels. Graphical abstract.

Determination of Morphological Parameters of Supported Gold Nanoparticles: Comparison of AFM Combined with Optical Spectroscopy and Theoretical Modeling versus TEM

The morphology of small gold particles prepared by Volmer–Weber growth on sapphire substrates have been investigated by two different characterization techniques. First, by non-extensive atomic force microscopy (AFM) in combination with optical spectroscopy and modeling of the optical properties using a theoretical model, recently developed in our group. Second, by extensive transmission electron microscopy (TEM). Comparing the results obtained with both techniques demonstrate that for small gold nanoparticles within the quasistatic limit, the morphological properties can be precisely determined by an appropriate theoretical modeling of the optical properties in combination with simple AFM measurements. The apparent mean axial ratio of the nanoparticles, i.e., the axial ratio that corresponds to the center frequency of the ensemble plasmon resonance, is obtained easily from the extinction spectrum. The mean size is determined by the nanoparticle number density and the amount of deposited material, measured by AFM and a quartz micro balance, respectively. To extract the most probable axial ratio of the nanoparticle ensemble, i.e., the axial ratio that corresponds to the most probable nanoparticle size in the ensemble, we apply the new theoretical model, which allows to extract the functional dependence of the nanoparticle shape on its size. The morphological parameters obtained with this procedure will be afterwards compared to extensive TEM measurements. The results obtained with both techniques yield excellent agreement. For example, the lateral dimensions of the nanoparticles after deposition of 15.2 × 1015 atoms/cm2 of gold has been compared. While a mean lateral diameter of (13 ± 2) nm has been extracted from AFM, optical spectroscopy and modeling, a value of (12 ± 2) nm is derived from TEM. The consistency of the results demonstrate the precision of our new model. Moreover, since our theoretical model allows to extract the functional dependence of the nanoparticle size and shape, a relatively simple analysis is sufficient for a full characterization of small noble metal nanoparticles.

Silicone Intubation and Dacryocystographic Finding in Incomplete Nasolacrimal Duct Obstruction

Purpose: To assess the relationship between the internal diameter of the nasolacrimal duct and the success rate of silicone tube intubation in incomplete nasolacrimal duct obstruction patients with epiphora. Methods: Dacryocystography was performed 80 patients with symptoms of epiphora and the anteroposterior (AP) diameters and the lateral diameters of the nasolacrimal ducts were measured. These measurements were compared between the group of patients who demonstrated improvement after the operation, and the group without symptom improvement. Results: The mean length of the nasolacrimal duct in the group with nasolacrimal stenosis was 11.70.1 mm, the mean lateral diameter was 1.00.2 mm, and the mean AP diameter was 1.10.1 mm. The AP diameter of the symptomatic nasolacrimal duct in the group with successful postoperative results was 1.10.1 mm, and 0.90.1 mm in the group with unsuccessful results. The group with successful postoperative results had an average of 18.17.0% stenosis in the side of the eye with nasolacrimal duct stenosis compared with the asymptomatic side, and the group with unsuccessful postoperative results had an average of 34%3.6% stenosis. Conclusions: In cases with nasolacrimal duct stenosis, the success rate of silicone tube intubation was high when the AP diameter of the nasolacrimal duct was more than 1.10.1 mm and when the stenosis was less than 18.17.0% in the symptomatic side compared with the opposite side. These results are expected to help predict the success rates when preoperatively planning silicone tube intubation.

Dosage dependence of Ge quantum dots grown on carbon-implanted Si substrates

Carbon implantation effects on self-assembled Ge quantum dots (QDs) have been investigated. Carbon atoms were implanted at different dosage, 9.0×10 14, 4.5×10 15, and 9.0×10 15 ions/cm 2 using the same acceleration energy of 20 keV. A nominal amount, 6 monolayer (ML), of Ge was grown on the substrate at different growth temperatures ranging from 500 to 600 °C using solid source molecular beam epitaxy. The smallest Ge QDs with a 13 nm mean lateral diameter, a 1.2 nm mean height, and an areal density of 2.0×10 11 cm −2 were obtained using the lowest dosage substrate at 550 °C. Raman measurement is carried out to investigate the optical phonons and strain.

Growth temperature dependence on the formation of carbon-induced Ge quantum dots

Carbon has been exploited to form Ge quantum dots since it can provide effective nucleation sites. In this study, C-induced Ge quantum dots grown by solid source molecular beam epitaxy are investigated as a function of pre-deposited C coverage, overgrown Ge coverage, and substrate temperature using atomic force microscopy. The smallest quantum dots with a 300 Å mean lateral diameter, a 50 Å mean height, and an areal density of 3.0×1010 cm−2 are obtained with 0.1 monolayer C pre-deposition and a 3 monolayer thick Ge overlayer. Growth temperature dependence for the Ge dot growth reveals that the dot density and size are abruptly changed by two orders of magnitude near 500°C. This is attributed to the difference in the temperature-dependent surface diffusivities of Ge and C adatoms on Si(100) substrate. The experimental results suggest that growth temperature plays a key role and should be kept below 500°C.

Large grain polycrystalline silicon by low-temperature annealing of low-pressure chemical vapor deposited amorphous silicon films: Miltiadis K Hatalis and David W Greve, J appl Phys, 63, 1988, 2260–2266

Carbon has been exploited to form Ge quantum dots since it can provide effective nucleation sites. In this study, C-induced Ge quantum dots grown by solid source molecular beam epitaxy are investigated as a function of pre-deposited C coverage, overgrown Ge coverage, and substrate temperature using atomic force microscopy. The smallest quantum dots with a 300 Å mean lateral diameter, a 50 Å mean height, and an areal density of 3.0×1010 cm−2 are obtained with 0.1 monolayer C pre-deposition and a 3 monolayer thick Ge overlayer. Growth temperature dependence for the Ge dot growth reveals that the dot density and size are abruptly changed by two orders of magnitude near 500°C. This is attributed to the difference in the temperature-dependent surface diffusivities of Ge and C adatoms on Si(100) substrate. The experimental results suggest that growth temperature plays a key role and should be kept below 500°C.

Pyramidal tract of the cat: axon size and morphology.

The purpose of this work was to determine the number and morphology of pyramidal tract (PT) axons in the cat, using electron microscopy, modern methods of fixation, and computer-assisted morphometric analysis. Sections taken at the level of the medullary pyramids in three animals were fixed and magnified up to 10,000 X to produce photomicrographs. Morphological data were entered into computer files for analysis by tracing axon perimeters on micrographs mounted on a digitizer tablet. The number of axons per PT averaged 415,000, of which 88% were myelinated and 12% were unmyelinated. 90% of the myelinated axons fell in the diameter range 0.5-4.5 microns. Axons larger than 9 microns diameter accounted for 1% of the total; the largest were 20-23 microns. Myelinated axon mean diameter was 1.98 microns; because of the skewed distribution, with many small axons and a few very large axons, median diameter was 1.60 micron. Size distribution was relatively uniform throughout the PT cross section, with all sizes represented in all regions. However, the more medial regions had a higher proportion of small fibers than the more lateral regions: mean medial diameter was 1.85 micron while mean lateral diameter was 2.09 microns. Myelin sheath thickness averaged 7.9% of fiber diameter for axons up to 11 microns, but was constant at 0.9 micron for larger fibers. Myelinated fibers were distorted from the circular shape in cross section, with a mean circularity index (or form factor) of 0.85, which implies that the fibers could swell about 15% without rupture of the cell membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue--air ratios for whole body irradiation with cobalt 60 gamma rays.

Total body irradiation with 60Co γ rays has been used since about 1966 for the treatment of acute leukaemia (Johnson, 1968; Buckner et al., 1970; Thomas et al., 1971; Miller et al., 1976). The method of irradiation developed by the Seattle group (Thomas et al., 1975) requires knowledge of the dose at the mid-line of the body for calculation of the treatment time. Published data of tissue-air ratios (TAR) for elongated fields like the dimensions of a human body in the lying position are not available. It is only known from measurements carried out by Faw and Glenn (1972) that the TAR values along the central axis of the beam for square fields greater than 50 × 50 cm2 show an effect of saturation. The objective of our investigations was to find TAR values for the mid-line of a human body. An Alderson phantom with a length of 150 cm, a mean lateral diameter of 30 cm and a mean A.P. diameter of 21 cm was used. The irradiation was carried out in a lateral direction with a field size of 165 × 30 cm2, the centre of the beam being coincident with the diameter below the umbilicus. The source-mid-line distance was 4 m, which gives a decrease in air-dose of less than 4% at the ends of the phantom.