HOTTIP Research Articles

Clean cane with nitrogen fixing bacteria

A clean cane is sugarcane is free from all known sugarcane diseases. The importance of using disease-free clean cane as the planting material in commercial production of sugarcane is well-known. The productivity increase could be more than 50% depending on the disease and variety involved. An efficient way of producing clean cane involving the combination of hot water treatment (HWT), thermotherapy and meristem tip culture is mentioned here. This method is well accepted in Brazil. The importance of the nitrogen fixing bacteria (NFB) to the growth of plants is also well-known and the inoculation of Rhizobium, the soybean’s NFB is a common practice in the soybean culture in Brazil, dispensing totally the need of application of N-fertilizers during the production cycle. In the case of sugarcane, 3 NFBs have been isolated by Dr. Dobereiner’s group and were found to be quite common in Brazilian sugarcane varieties. These are theHerbaspirillum rubrisubalbicans, Herbaspirillum seropedicae andAcetobacter diazotrophicus. All of them are endophytic and exist in high amount in stem, leaf and root of sugarcane. HWT is believed not to have an effect on the NFB in sugarcane, while meristem tip culture could clean the NFB as well as other microorganisms. However, NFB is very easy to be re-inoculated into sugarcane. Spraying NFB on cuttings during planting before covering was found possible for this purpose, and clean cane was found to be infected more easily than non-treated cane. Thus, clean cane with NFB could be used as an efficient material for sugarcane commercial production under biological nitrogen fixation conditions.

Pulsational Evidence for Mass Loss in NGC 1866 Cepheids

Available observational data for the 20 known Cepheids in the LMC cluster NGC 1866 have been compared with Hubble Space Telescope observations, discovering in the cluster central region five additional variables, one of which appears to be a Cepheid candidate. We also reach the conclusion that only the photometric data for the seven variables in the cluster periphery appear accurate enough to allow a meaningful comparison with the results of pulsational theories. Out of these seven well-observed Cepheids, we find that the six probable cluster members are located in the color-magnitude diagram at the hot tip of the blue nose experienced by He-burning giants. Since evolutionary theory predicts for these giants an original mass on the order of 4 M⊙, we extend down to ~3 M⊙ the theoretical pulsational scenario already presented for M ≥ 5.0 M⊙. On this basis we discuss the four member Cepheids with VI magnitudes accurate enough to produce robust constraints on the pulsating structures. Among these variables, one finds evidence for a spread of masses by about 7%, with the structures following a tight mass-luminosity relation. Moreover, we show that periods and colors of the Cepheids give a robust indication of pulsator masses smaller than predicted by stellar evolution theory without mass loss, independently of the occurrence of core overshooting.

H-NMR spin-lattice and correlation times of burned soft-tissue after treatment with an infrared pulsed laser device.

The aim of this study was to investigate the spin-lattice (T(1), 1/T(1)) and correlation times (tau(c)) of burned soft-tissue after treatment with an infrared (IR) pulsed laser device (IPLD, 904 nm pulsed at 3 MHz). Seven groups (GI-GVII), each consisting of four albino rats, were used. Groups I-VI were anesthetized and burned with a hot tip: GI, GIII, GV were not irradiated; GII, GIV, GVI were irradiated at 0; 0 and 24; and 0, 24, and 48 hours, respectively. A control group (GVII) was neither burned nor irradiated. Samples from all groups were evaluated using a 90 MHz hydrogen nuclear magnetic resonance (H-NMR) spectrometer. An unpaired Student's t-test and an ANOVA I were preformed (alpha = 0.05). At 0 and 24 hours, 1/T(1) and tau(c) data revealed significant differences between GVII and both the non-irradiated (GI, GIII), and irradiated (GII, GIV) groups. At 48 hours, only the difference in tau(c) between GVII and the irradiated group (GVI) remained significant. Spin-lattice data reflected significant changes in tissues induced by the burn and a tendency towards control values for all burned groups. Meanwhile, the tau(c) value of GVI suggests the possibility of enhanced reparative effects attributable to chaotic intra- and inter-molecular energy transport to biopolymers in injured soft-tissue.

Analytical Determination of Localized Heat Damage in Fiberglass Reinforced Resin Beams Using the Frequency Response Shifting

The dynamic response of a localized, heat-damaged, fiberglass-reinforced epoxy cantilever beam is obtained as a function of damaged length and damage severity. A heat-damaged area causes a reduction in the local stiffness of the beam and introduces a complex damping in the damaged zone. These variations in the local mechanical properties could result in changing vibration characteristics of the beam. The variations in the system characteristic could then be used to assess the structural integrity of the composite beam. A cantilever beam made of a glass fiber-resin composite material and damaged by a hot tip contact element and a laser beam is evaluated for its dynamic response using numerical methods. The laser beam caused local melting of many fibers in the damaged area and thus reducing the stiffness of the beam in the damaged area. The beam is analyzed by modeling it as a lumped system and a continuous system and by a finite element. The goal of the research is to find out whether the changes in the frequency response of the damaged beam can be used as a diagnostic tool for estimating the severity of the damage. The results show that the size and location of damage are equally as important as the local stiffness and damping of the damaged region in terms of their effects on the beam resonant frequencies. The results indicate that the resonance frequencies may not be suitable parameters for estimating the residual tensile strength of the composite. A 50% reduction in the local bending rigidity produced relatively little change in the system first resonance frequency. In contrast, it significantly reduced the residual tensile strength of the composite.

Millipede is hot tip for memory

Millipede is hot tip for memory

Short‐Term bioeffects of an infrared pulsed laser device on burned rat skin monitored by transverse relaxation times (NMR)

Background and Objective The aim of this study was to determine whether the application of an infrared pulsed laser device (IPLD) on the burned skin of rats induced significant changes in the water dynamics of the burned tissues as measured by nuclear magnetic resonance (NMR) at a proton frequency of 90 MHz by using transverse relaxation times (T2, I/T2). Study Design/Materials and Methods Seven groups (GI–GVII), each consisting of four albino rats (Sprague-Dawley), of 12–14 weeks of age were used in the experiment. Rats in GI–GVI were anesthetized and burned with a hot tip. GI, GIII, GV were not irradiated. GII, GIV, GVI were irradiated at 0 hours; 0 and 24 hours; and 0, 24, and 48 hours, respectively. Rats in GVII served as controls and were neither burned nor irradiated. Samples from all groups were obtained and monitored by NMR by using transverse relaxation times (T2 and 1/T2). An unpaired Student's t-test and a one-way analysis of variance (ANOVA I) were preformed on the mean values obtained (T2, 1/T2). The statistical design was chosen to give a 95% power of contrast 1-β (1/T2). The modulated beam of the IPLD used is composed of two superposed waves; a carrier wave (3 MHz), and a drive force wave in the near infrared (904 nm, f = 1014 Hz). A dose of 1.5 × 103 J/M2 per session was applied by placing the IPLD directly over the burned tissue by using a top-hat distribution. Results The results of a t-test on the T2 and 1/T2 values did not show statistically significant differences at 0 and 24 hours between the irradiated groups, the nonirradiated groups, and the nonburned nonirradiated (control) group. Nonetheless, at 48 hours after the burn, we found a statistically significant difference in the 1/T2 values for the irradiated specimens compared with the nonirradiated specimens and the control group. Furthermore, the variance of the 1/T2 values as a function of time showed a tendency to decrease significantly only for the irradiated specimens. Conclusion These findings show possible effects on the water dynamics of burned rat tissue in a short term as a result of the IPLD's application. Lasers Surg. Med. 27:411–419, 2000. © 2000 Wiley-Liss, Inc.

Short-term bioeffects of an infrared pulsed laser device on burned rat skin monitored by transverse relaxation times (NMR).

The aim of this study was to determine whether the application of an infrared pulsed laser device (IPLD) on the burned skin of rats induced significant changes in the water dynamics of the burned tissues as measured by nuclear magnetic resonance (NMR) at a proton frequency of 90 MHz by using transverse relaxation times (T2, I/T2). Seven groups (GI-GVII), each consisting of four albino rats (Sprague-Dawley), of 12-14 weeks of age were used in the experiment. Rats in GI-GVI were anesthetized and burned with a hot tip. GI, GIII, GV were not irradiated. GII, GIV, GVI were irradiated at 0 hours; 0 and 24 hours; and 0, 24, and 48 hours, respectively. Rats in GVII served as controls and were neither burned nor irradiated. Samples from all groups were obtained and monitored by NMR by using transverse relaxation times (T2 and 1/T2). An unpaired Student's t-test and a one-way analysis of variance (ANOVA I) were preformed on the mean values obtained (T2, 1/T2). The statistical design was chosen to give a 95% power of contrast 1-beta (1/T2). The modulated beam of the IPLD used is composed of two superposed waves; a carrier wave (3 MHz), and a drive force wave in the near infrared (904 nm, f = 1014 Hz). A dose of 1.5 x 10(3) J/M2 per session was applied by placing the IPLD directly over the burned tissue by using a top-hat distribution. The results of a t-test on the T2 and 1/T2 values did not show statistically significant differences at 0 and 24 hours between the irradiated groups, the nonirradiated groups, and the nonburned nonirradiated (control) group. Nonetheless, at 48 hours after the burn, we found a statistically significant difference in the 1/T2 values for the irradiated specimens compared with the nonirradiated specimens and the control group. Furthermore, the variance of the 1/T2 values as a function of time showed a tendency to decrease significantly only for the irradiated specimens. These findings show possible effects on the water dynamics of burned rat tissue in a short term as a result of the IPLD's application.

Simple method of removing a vacuum-formed matrix from a cast

cation of a fixed provisional prosthesis,1-4 and stents for radiographic examination or the surgical stage in implant therapy.5,6 Carbide burs or hot instruments have been the instrument of choice to remove the plastic sheet after the matrix has been formed on the cast. However, burs may jeopardize the surface of the cast and a hot instrument needs to be heated repeatedly. This article presents a simple method to remove the plastic sheet from the cast by using a butane gaspowered soldering iron to cut along the border of the matrix without damaging the original cast (Figs. 1 and 2). The soldering iron provides a constant and continuous hot tip to cut the matrix from the vacuumformed shell. The cast surface is not damaged and remains intact after removing the matrix from the cast. REFERENCES

Radiative exchange of heat between nanostructures

Surfaces in close proximity exchange heat through evanescent photon tunnelling modes as well as by freely propagating modes. These additional near field contributions to radiation scale with separation, d, between surfaces as d-2 and are dominant at spacings d<<T, a typical wavelength at temperature T. We calculate simple expressions for the photon tunnelling and find that there are drastic effects in many nanostructured systems, for example in the scanning tunnelling microscope. The results are linked to quantum information theory which dictates that the maximum heat tunnelling current in any one channel is determined by the temperature alone. Consequences for the scanning tunnelling microscope are discussed, where a hot tip may cause intense local heating of a surface without actually being in physical contact, hence desorbing molecular species, or even modifying the surface itself: a possible extension of the STM's capacity for surface modification. A further extension of this concept is proposed in the form of a `heat stamp' capable of delivering a high definition pattern of heat to a second surface.

Nondestructive Evaluation of Fiberglass Reinforced Plastic Subjected to Combined Localized Heat Damage and Fatigue Damage Using Acoustic Emission

The effect of fatigue damage to unidirectional fiberglass composite specimens with prior contact heat damage was investigated. After damaging the specimens by contacting them to a hot tip at 360°C, the specimens were subjected to fatigue loading at cyclic stress amplitude corresponding to 65% of the specimens' ultimate tensile strength. The fatigue experiments was halted after 3,000 cycles. The specimens were then subjected to tensile tests while monitoring their acoustic emission (AE) activity. In addition, acoustic emission activities of undamaged and contact heat-damaged specimens were monitored during tensile tests for comparison with specimens with combined fatigue and heat damage. AE activities of all specimens can be categorized into three regions: an early rise in activity, a relatively dormant period in activity, and a high exponential activity before failure. The early rise in activity did not appear on the specimens with combined contact heat and fatigue damage. For undamaged and contact heat-damaged specimens, the period of the dormant activity was independent of the contact heat duration of less than 15 minutes. However, the period was a function of the contact heat duration for combined contact heat and fatigue damaged specimens. Analyzing event duration distribution identified micro-mechanisms of the damage growth upon tensile loading. AE-stress delay concept was used to predict the state of the damage in the composite. A correlation between stress delay parameter and damage parameter was obtained for all of the specimens. Fatigue life of contact heat damaged specimen was also studied. It was found that localized heat damage reduced the fatigue life significantly. Loss of matrix to transfer the load to the fibers uniformly was believed to be responsible for the reduction in the fatigue life.

Ultrasonic capacitance transducers for flow and temperature tomography in air

Capacitance transducers have been constructed that can operate at frequencies of up to 2 MHz in air, over a wide bandwidth, and with good efficiency. These have been used to propagate signals in air across regions containing variations in air flow and temperature. A source and receiver pair were scanned along a set of projections under computer control, allowing various ray paths across a chosen cross section to be selected. For each location, the received waveform was digitized and recorded, and the propagation time determined from cross-correlation techniques. The data were then used to form tomographic images, which corresponded to variations in either temperature or flow speed, both of which affect the local acoustic velocity. In one experiment, an air-jet was imaged at various distances from the nozzle. In another, the temperature variations in air above a hot metal tip were determined. Images will be shown for both sets of experiments, and the usefulness of the technique discussed.

New pediatric applications and techniques for balloon valvuloplasty: Tetralogy of Fallot, complex pulmonary stenosis/atresia, and pulmonary atresia with intact septum

Palliative pulmonary balloon valvuloplasty in Tetralogy of Fallot has been proposed to promote growth of the pulmonary valve so that it can be incorporated in a later repair without transannular patch to avoid the late complications from free pulmonary regurgitation. We have used the procedure in patients with severe hypoxemia less than 3 months old. Synopsis of 141 published cases and our own experience in 15 patients shows technical success in 93%, a complication rate of 5%, cyanotic spells in 9%, and a mortality of 0.6%. Arterial oxygen saturation instantly increased from 78 to 91%. Based on the intention to treat, emergent surgery was avoided in 65%. Despite a significant increase in pulmonary valve diameter, the incidence of transannular patch was reduced in only one study, partly reflecting the surgeon's preference. Palliative pulmonary balloon valvuloplasty can also promote pulmonary artery growth in other complex cyanotic lesions. In pulmonary valve atresia with intact ventricular septum without right ventricular dependent coronary circulation, catheter valvotomy and subsequent pulmonary balloon valvuloplasty can establish right ventricle to pulmonary artery continuity. Perforation of the atretic valve can be accomplished with a bare wire (rarely), with a hot tip laser wire or with a radiofrequency wire if available. We use a standard steerable 5 French electrode catheter to deliver radiofrequency pulses at 8–26 watt with subsequent dilatation using a 7–8 mm low profile balloon. If tricuspid valve diameter or right ventricular size are below normal, additional stenting of the ductus with a flexible stent expanded to 4–5 mm diameter should be performed. In patients with severe hypoplasia, stent placement across the outflow tract is necessary. With this strategy, overall outcome should be superior to the published data on 68 attempted catheter perforations: Out of the 74% technically successful procedures, only 47% remained without surgical intervention during early follow-up.

Laser angioplasty: enough to make your blood boil!

Some of the effects on blood and contrast agents of a laser angioplasty device of the "hot tip" variety have been studied. This device liberates iodine from contrast agents both in the form of soluble free iodide and in the form of solid elemental iodine debris. Some of the solid iodine does not adhere to the probe but remains free and, in vivo, would be available to embolize distal vessels. The liberation of iodine occurs more readily with dimeric agents than with monomeric contrast agents regardless of whether they are ionic or non-ionic. Blood and blood/contrast agent mixtures exhibit local boiling in the vicinity of the hot tip laser probe. Blood so treated exhibits markedly accelerated clotting as indicated by measurements of whole blood clotting times. Untreated blood to which aliquots of blood treated as described above are added also exhibits accelerated clotting. The laser tip, operating in blood/iodine mixtures, becomes coated with a friable black/brown deposit which analysis reveals to be a mixture of carbon and iodine. Again, some of this particulate debris fails to adhere to the probe and is available as free embolic material. The possible practical clinical implications of these observations are discussed.

Laser thermal venous obliteration: experimental results in the rat model

In an animal study, thermal laser application was tested for inducing venous thrombosis. In 54 rats, metal-tipped laser catheters ("hot tip") were trans-jugularly inserted into the distal inferior caval vein which was thermally damaged by laser pulses of 4-7 W. Suitable energy levels were defined in an acute experiment in 25 rats. Chronic experiment with 29 rats included survival time of two weeks after laser application, autopsy and histological work-up of the caval vein. In 27 rats, laser application was successfully performed and induced thrombosis in 17 animals. Perforation of the caval vein occurred in 10 rats. Thermal laser application is capable of inducing venous thrombosis. The power ranges inducing thrombosis or thermal perforation are, however, too narrow to allow safe clinical application of this technique.

Technique of percutaneous laser-assisted valve dilatation for valvar atresia in congenital heart disease.

To investigate the efficacy and safety of transcatheter laser-assisted valve dilatation for atretic valves in children with congenital heart disease. Prospective clinical study. Supraregional paediatric cardiology centre. Eleven children (aged 1 day-11 years; weight 2.1-35.7 kg) with atresia of pulmonary (10) or tricuspid (one) valve underwent attempted laser-assisted valve dilatation as part of the staged treatment of their cyanotic heart disease. After delineating the atretic valve by angiography and/or echocardiography a 0.018 inch "hot tip" laser wire was used to perforate the atretic valve. Subsequently the valve was dilated with conventional balloon dilatation catheters up to the valve annulus diameter. Laser-assisted valve dilatation was successfully accomplished in nine children. In two neonates with pulmonary valve atresia, intact ventricular septum, and coexistent infundibular atresia the procedure resulted in cardiac tamponade: one died immediately and one later at surgery. During a follow up of 1-17 months (mean 11) two infants with pulmonary valve atresia and intact ventricular septum died (one with congestive cardiac failure). The remainder are either well palliated and do not require further procedures (three), or are awaiting further transcatheter or surgical procedures because of associated defects (four). Laser-assisted valve dilatation is a promising adjunct to surgery in this high risk group of patients. It may avoid surgery in some patients, and may reduce the number of surgical procedures in those requiring staged operations.

Cobalt-catalysed growth of carbon nanotubes with single-atomic-layer walls

CARBON exhibits a unique ability to form a wide range of structures. In an inert atmosphere it condenses to form hollow, spheroidal fullerenes. Carbon deposited on the hot tip of the cathode of the arc-discharge apparatus used for bulk fullerene synthesis will form nested graphitic tubes and polyhedral particles. Electron irradiation of these nanotubes and polyhedra transforms them into nearly spherical carbon 'onions'. We now report that covaporizing carbon and cobalt in an arc generator leads to the formation of carbon nanotubes which all have very small diameters (about 1.2 nm) and walls only a single atomic layer thick. The tubes form a web-like deposit woven through the fullerene-containing soot, giving it a rubbery texture. The uniformity and single-layer structure of these nanotubes should make it possible to test their properties against theoretical predictions.

閉塞性動脈硬化症に対するレーザー治療

We carried out Laser angioplasty by the metal hot tip contact method with either the Argon laser or Nd-YAG laser and by the pulse laser direct beaming method aided by the Ho-YAG laser. The study was conducted on 69 patients with arteriosclerosis obliterans who had visited our hospital with a chief complaint of intermittent claudication.The initial success rates were 86% in Argon laser, 90% in Nd-YAG laser, and 87% in Ho-YAG laser. The long-term patency after surgery were 68% in the Argon laser, 64% in the Nd-YAG laser and 84% in the Ho-YAG laser.Laser angioplasty is an effective technique for the treatment of arteriosclerosis obliterans which can be performed within a short period of time in high risk cases such as those complicated by coronary artery lesions. Combined with bypass surgery, laser angioplasty enabled complete revascularization of the target area.We proved it possible to obtain a satisfactory initial success rate and favorable long-term patency by carefully selecting the lesion through meticulous observation with the fiberoptic angioscopy.

Thermal ablation of perfused porcine left ventricle in vitro with the neodymium-YAG laser hot tip catheter system.

Catheter ablation in the treatment of arrhythmias has been limited by the small lesion size achievable with a radiofrequency energy source. The feasibility of catheter ablation with a neodymium-yttrium-aluminum-garnet (Nd-YAG) laser hot tip catheter was tested because of the capability of achieving a high catheter-tissue contact temperature, which should result in a larger lesion. In a model of isolated perfused pig hearts, 77 endocardial lesions were produced with powers of 1 to 10 watts and peak measured temperatures of 40 degrees to 318 degrees C. Lesion size correlated with power and temperature, but the correlations were poor. High temperature lesions resulted in significant intramyocardial catheter penetration and only marginal increased lesion width. Catheter ablation with a Nd-YAG laser hot tip catheter is feasible, but carries a risk of perforation at high powers. High temperatures result in tissue dessication with a resultant fall in thermal conductivity that limits the radius of thermal injury and overall lesion size.

Three years experience with thermal and excimer lasers in the treatment of peripheral artery disease

Laser angioplasty is an effective tool to revascularize peripheral artery disease, but the major limitation is a high restenosis rate. Our experience with the hot tip laser system has shown a high primary success, 59–73% of the arteries were patent at 18 months, although 21% resulted in severe restenosis. The excimer laser seems to have a better long-term patency. Histology of restenosis specimens removed by atherectomy, shows the key role of the smooth muscle cells in this process.

Percutaneous laser valvotomy with balloon dilatation of the pulmonary valve as primary treatment for pulmonary atresia.

A neonate with pulmonary atresia and an intact ventricular septum with a tripartite right ventricle was successfully treated by percutaneous balloon dilatation of the pulmonary valve. This was facilitated by previous laser valvotomy with a hot tip Trimedyne laser wire. There were no major complications. Four weeks later the patient was discharged home on no medication with peripheral oxygen saturations of 70% in air.