Nanopore formation process in artificial cell membrane induced by plasma-generated reactive oxygen species.

We investigated morphological change of an artificial lipid bilayer membrane induced by oxygen radicals which were generated by non-equilibrium atmospheric pressure plasma. Neutral oxygen species, O((3)Pj) and O2((1)Δg), were irradiated of a supported lipid bilayer existing under a buffer solution at various conditions of dose time and distances, at which the dose amounts of the oxygen species were calculated quantitatively. Observation using an atomic force microscope and a fluorescence microscope revealed that dose of the neutral oxygen species generated nanopores with the diameter of 10-50 nm in a phospholipid bilayer, and finally destructed the bilayer structure. We found that protrusions appeared on the lipid bilayer surface prior to the formation of nanopores, and we attributed the protrusions to the precursor of the nanopores. We propose a mechanism of the pore formation induced by lipid oxidation on the basis of previous experimental and theoretical studies.

Structural analysis of multi-walled carbon nanocoils synthesized with Fe-Sn catalyst supported on zeolite.

Thin carbon nanocoil (CNC) with a fiber diameter of less than 50 nm was synthesized by catalytic chemical vapor deposition using Fe-Sn catalyst supported on zeolite. The chemical vapor deposition parameters of reaction temperature, gas flow rate of N2 as dilute gas and C2H2 as source gas were 650-750 degrees C, 1000 ml/min and 50-300 ml/min respectively. Transmission electron microscopic observation revealed that thin CNCs had a hollow and multi-walled structure with cylindrical graphitic layers. More than 90% of the CNCs obtained were multi-walled CNCs (MWCNCs), and the remainder was columnar CNCs without a hollow structure. Three-dimensional images of an MWCNC with Au nanoparticles on its surface were reconstructed by electron tomography and confirmed that the MWCNC had a three-dimensional helical shape.

Splitting and flattening of helical carbon nanofibers by acid treatment.

Helical carbon nanofibers (HCNFs), such as the carbon nanocoil (CNC) and the carbon nanotwist (CNTw), were synthesized by catalytic chemical vapor deposition using a substrate. HCNFs are classified into round and angular types according to the fiber cross-sections. When four types of HCNFs (round-type CNC and CNTw, angular-type CNC and CNTw) were acidified in a 30% hydrogen peroxide solution, only the angular type CNC was found to show a drastic shape change. The shape change observed was a splitting followed by a flattening of the angular type CNCs. The CNC was split into two or three thinner flat fibers. As a function of the treatment temperature, the weight of the CNCs decreased above 80 degrees C and the CNCs were etched effectively at 140 degrees C. The longer the reaction time the lower the weight of the CNCs, and the weight loss reached a saturation point when the reaction time was greater than 45 min at 140 degrees C. The splitting and flattening of the CNC occurred during the weight loss process. To analyze the CNC structure, electron tomography of the as-grown and acid-treated CNCs was obtained using a computerized tomograph system with transmission electron microscopy (TEM). The 3D-images were constructed using the TEM images collected at different tilt angles. The 3D image reconstructions showed that the CNCs had a tubular structure and were composed of several helical fibers which act as frames.

Is the diameter or chirality distribution of single-walled carbon nanotubes selected in the synthesis process?

Based on recent theoretical photoluminescence intensity calculations, the population densities of sixteen semiconducting single-walled carbon nanotubes grown by alcohol catalytic chemical vapor deposition were estimated for two different temperatures. The profiles of population density merely as functions of tube-diameter or chiral angle are found to be widely scattered. However, systematic profiles are detectable when separately split into (2n + m), (n + 2m) and (n - m) family arrays. Apart from these well-knit family behaviors, the population densities of the group of nanotubes forming another three possible series [viz. constant-n, constant-m and constant-(n + m)] also show evidence of good correlations. Hence, a two-dimensional chiral-zone selective growth principle is hypothesized.

Speech evaluation and dental arch shape following pushback palatoplasty in cleft palate patients: Supraperiosteal flap technique versus mucoperiosteal flap technique.

BACKGROUND: The aim of this study was to evaluate and compare the maxillary dental arch shape and speech of cleft palate patients following pushback palatoplasty using either the supraperiosteal flap technique or the mucoperiosteal flap technique. PATIENTS: Sixty-two patients (29, cleft palate only; 33, unilateral cleft lip, alveolus and palate) operated on by the supraperiosteal technique and 47 patients (23, cleft palate only; 24 unilateral cleft lip, alveolus and palate) by the mucoperiosteal technique were reviewed in this study. STUDY DESIGN: Dental arch shape and speech proficiency at preschool and school age were evaluated in all patients. RESULTS: Dental arch shapes were classified as U type (good dental arch shape) and V type (narrow dental arch shape). In cleft palate only patients, U type was observed in 90% of the supraperiosteal group and 83% of the mucoperiosteal group. In unilateral cleft lip, alveolus and palate patients, U type was observed in 85% of the supraperiosteal group, while only in 33% of the mucoperiosteal group. In cleft palate only patients, normal speech at school age was observed 100% of the supraperiosteal group and 83% of the mucoperiosteal group. In unilateral cleft lip, alveolus and palate patients, normal speech at school age was observed in 97% of the supraperiosteal group and 75% of the mucoperiosteal group. Misarticulation was frequently found in patients with the V type of dental arch shape. CONCLUSION: It is suggested that pushback palatoplasty using the supraperiosteal technique is more advantageous for speech development compared with the mucoperiosteal technique.

Dento-alveolar development in unilateral cleft lip, alveolus and palate.

BACKGROUND AND OBJECTIVE: Palatal surgery for cleft lip, alveolus and palate is considered to have the most powerful negative impact on maxillary growth. The aim of this study was to compare dento-alveolar development of the permanent dentition and morphology of the palate after surgery in unilateral cleft lip, alveolus and palate patients following two types of palatoplasty: supraperiosteal flap vs mucoperiosteal flap technique. PATIENTS: Thirty-eight patients born between 1976 and 1983 with a complete unilateral cleft of lip, alveolus and palate were studied. Fifteen patients were treated with supraperiosteal flaps (SP group), and the other 23 patients with mucoperiosteal flaps (MP group). In this cross-sectional study, dental casts of stage IV A of Hellman's dental age in each patient were used. METHODS: The following distances were measured: (1). transverse distance C-C', (2). transverse distance M-M', (3). palatal length, (4). palatal height. RESULTS: No statistically differences were seen between the SP and MP groups regarding C-C' and M-M'. However, palatal length and palatal height were significantly greater in the SP than in the MP group. CONCLUSION: The technique that leaves no denuded palatal bone is considered to be advantageous for the development of the alveolar process.

Comparison of palatal sensitivity after treatment of cleft palate by a supraperiosteal or mucoperiosteal flap.

We compared palatal sensitivity after push-back palatoplasty in patients operated on with a conventional mucoperiosteal flap and with a supraperiosteal flap. We studied 37 patients, whose mean age was 18 years (range 11-28), with unilateral cleft lip, alveolus, and palate who required palatoplasty at our clinic; 18 patients had a supraperiosteal, and 19 a mucoperiosteal flap. Thresholds of palatal sensitivity were measured with Semmes-Weinstein monofilaments. The mean values of thresholds of palatal sensitivity in patients who had a push-back palatoplasty were higher than those in a normal control group. The mean values for patients who had a supraperiosteal flap were significantly lower than those who had a mucoperiosteal flap.