Micro-CT for Biological and Biomedical Studies: A Comparison of Imaging Techniques

Several imaging techniques are used in biological and biomedical studies. Micro-computed tomography (micro-CT) is a non-destructive imaging technique that allows the rapid digitisation of internal and external structures of a sample in three dimensions and with great resolution. In this review, the strengths and weaknesses of some common imaging techniques applied in biological and biomedical fields, such as optical microscopy, confocal laser scanning microscopy, and scanning electron microscopy, are presented and compared with the micro-CT technique through five use cases. Finally, the ability of micro-CT to create non-destructively 3D anatomical and morphological data in sub-micron resolution and the necessity to develop complementary methods with other imaging techniques, in order to overcome limitations caused by each technique, is emphasised.

Difference between conventional and modern methods for examination of fingerprints

The impression of frictional ridges of the finger is known as fingerprints. Owing to this uniqueness, the fingerprints have long been used to identify a person since Ancient times. In any crime scene the presence of fingerprint makes the identification of the Culprit very easy. The fingerprints can also easily be embedded on any item such as paper, Clothing and body of the victim. To utilize this uniqueness of fingerprints forensic experts devised many techniques to obtain a clear fingerprint. These come under two categories i.e. Conventional and modern methods. The conventional methods are although important but there are limitations of them. Just take the example of powder method. Powder method require different powders for different Surfaces and colors, but modern method like quantum dots method can easily detect Fingerprints on all surfaces regardless of their color giving great resolution in seconds. Other methods like physical developer method is very time consuming and expensive, carbon Black method creates mess and does not work on porous surface, iodine fuming and Naphthaloflavin does have an advantage that it can bring up prints on skin also but it does not Work on metallic surfaces. VMD also fails on heavy plastic polymers and body oils. But some modern methods like nanotechnology can obtain high resolution prints old and dried prints also within 3 minutes. Laser technology is very fast, accurate and can be used for Fingerprints up toten years old also on any surface without any mess. Multimetal deposition Method can even be used to identify smokers and drug addicts and can be used Porous, non-porous and wet surfaces.

Optical navigation for nanosatellite star trackers

This thesis looks at the effectiveness of using nanosatellite class star trackers to perform optical navigation. Although star trackers used for these missions lack the accuracy and sensitivity of sensors employed on larger spacecraft, they offer great resolution relative to its compact size. Two Extended Kalman Filter-based navigation filters illustrate the applications of this class of sensor. The first filter looks at horizon-based techniques using observations of Mars and its moons to assist the navigation filter in a hyperbolic approach. Results show low position (< 300 m) and velocity (< 0:15 m/s) errors as spacecraft reaches periapse. The filter formulation serves as a basis for a design case study exploring different possible sensor configurations for this mission type. The second filter looks at landmark-based techniques using absolute and relative landmarks as observations. Measurement frequency appears as a key parameter in this study, simulation results show position errors in the order of tens of kilometers, or better even if absolute landmarks are only available every 30 minutes. The accuracy of the results are validated through series of Monte Carlo simulation.

Optical navigation for nanosatellite star trackers

This thesis looks at the effectiveness of using nanosatellite class star trackers to perform optical navigation. Although star trackers used for these missions lack the accuracy and sensitivity of sensors employed on larger spacecraft, they offer great resolution relative to its compact size. Two Extended Kalman Filter-based navigation filters illustrate the applications of this class of sensor. The first filter looks at horizon-based techniques using observations of Mars and its moons to assist the navigation filter in a hyperbolic approach. Results show low position (< 300 m) and velocity (< 0:15 m/s) errors as spacecraft reaches periapse. The filter formulation serves as a basis for a design case study exploring different possible sensor configurations for this mission type. The second filter looks at landmark-based techniques using absolute and relative landmarks as observations. Measurement frequency appears as a key parameter in this study, simulation results show position errors in the order of tens of kilometers, or better even if absolute landmarks are only available every 30 minutes. The accuracy of the results are validated through series of Monte Carlo simulation.

Recurrent Pregnancy Induced Pemphigus Vulgaris: A Rare Case Report

Pemphigus vulgaris is a potentially life-threatening bullous autoimmune disease that can be triggered by various factors, one of which is pregnancy. Cases of pregnancy induced pemphigus are rare, and can result in devastating outcomes, both from the maternal or fetal perspectives if not treated promptly and adequately. The use of systemic corticosteroids is paramount to improve the outcome of the patient and fetus and it is a first-line treatment for the disease. Patients with a history of pemphigus should plan their pregnancies carefully, taking into consideration a minimum of 6 months remission before conception. This case report is about a 28-year-old woman with a history of pemphigus vulgaris that did not seek medical treatment of her pemphigus, which resulted in the intrauterine fetal death. The patient was treated with systemic corticosteroids and achieved great resolution to her blisters and overall wellbeing.

FABRICACIÓN DE PUNTAS DE FIBRAS DE CARBONO PARA MICROSCOPÍA DE SONDA DE BARRIDO

Los microscopios de Fuerza Atómica (AFM) con sonda diapasón requieren puntas muy agudas y livianas para obtener imágenes topográficas de gran resolución. Por otro lado, los microscopios de Efecto Túnel (STM) necesitan puntas agudas y conductoras. Ambos requerimientos pueden ser obtenidos usando fibras de carbono como material base para la fabricación de las puntas, con la ventaja adicional de ser un material con bajo nivel de oxidación. En este trabajo se presentan algunos resultados iniciales de la técnica de disolución anódica que ha permitido obtener puntas de carbono de rango nanométrico. La celda electroquímica consistió en la fibra de carbono como ánodo (7m de diámetro), un anillo de platino de 2mm de diámetro como cátodo y KOH como electrolito. Una gota del electrolito se suspendió del anillo de platino para posteriormente introducir la fibra dentro de la gota. La polarización de la celda se obtuvo por medio de una interfase electroquímica en el modo de crono-amperómetro, el cual permitió registrar las curvas corriente-tiempo para diferentes voltajes escalón. Se encontraron correlaciones entre la forma final de la punta y la molaridad del electrolito, voltaje anódico, tiempo de disolución y profundidad de inmersión de la punta en el electrolito. Por medio de microscopía electrónica de barrido se observó que se pueden obtener puntas con diámetros menores a 70 nm de manera reproducible. Palabras clave.- Fibra de carbono, Punta nanométrica, Crono-amperometría.. ABSTRACTThe Atomic Force Microscope (AFM) using a tuning fork as probe requires very sharp and light tips for obtaining topographic images with great resolution. On the other hand, Scanning Tunneling Microscopes (STM) needs sharp and conducting tips. Both requirements can be achieved using carbon fiber as the base material for the fabrication of the tips, with the additional advantage of being a material with a very low tendency to oxidize. In this work some initial results of the anodic dissolution technique are presented, which has permitted us to obtain the apex size of the tips in the nanometer scale. The electrochemical cell consists of the carbon fiber as the anode (7m diameter), a 2mm diameter Platinum ring as the cathode and Potassium Hydroxide as the electrolyte. A drop of the electrolyte is deposited on the Platinum ring and after that the carbon fiber is introduced into the drop. The polarization of the cell was obtained using a Potentiostat in Chrono-Amp mode, which permitted us to register Current vs. Time graphs for different values of potential applied. Correlations between the shape of the final tip and the molarity of the electrolyte, anodic potential, time for the anodic dissolution and the length of the carbon fiber beneath the air/electrolyte interface were found. Using Scanning Electron Microscopy, it was observed that tips with diameter lower than 70 nm can be obtained in a reproducible way.. Keywords.- Carbonfibre, Nanometer tip apex size, Chrono-amp..

Chapter XII Liking Life on My Own Account No Better, I Form a Great Resolution

In due time, Mr. Micawber’s petition was ripe for hearing; and that gentleman was ordered to be discharged under the act, to my great joy. His creditors were not implacable; and Mrs. Micawber informed me that even the revengeful bootmaker had declared in open...

The diameters of the fibres of the peripheral nerves of Octopus

The diameters and numbers of fibres have been measured throughout the peripheral nervous system. The nerves of the muscles that act upon the outside world contain few fibres, having very large and medium-sized fibres but no very small ones. Thus the muscles of the head receive 6000 fibres, the largest of 30 μ m diameter. The eye muscles receive 3300 fibres, reaching 24 μ m. The stellar nerve fibres are more numerous (150 000), but smaller (< 20 μ m). The preganglionic fibres joining the c. n. s. to the stellate ganglia are fewer than the postganglionic ones (4000, < 16 μ m). In some of the somatic motor nerves the longest bundles contain the largest fibres. However these are accompanied by a distinct group of smaller fibres, whose significance is uncertain. It is not clear that there is a distinct proprioceptor group. The fibres to the chromatophores are numerous (30000) and of medium diameter (< 12 μ m). The visceral motor and vasomotor nerves, however, contain hundreds of thousands of minute fibres (< 3 μ m). The significance of these numerous small fibres can hardly be to obtain great resolution of movement in such acts as secretion of saliva. Presumably the great number has a special significance. The fibres to the muscles of the buccal mass are more numerous and smaller than the somatic motor fibres, but fewer and larger than those for the viscera. The muscles of the arms and suckers have 3.0 x 10 6 fibres, all < 6 μ m, originating from neurons within the arms. They are controlled from the brain by relatively few but large fibres (32000, < 26 μ m). There is also a reduction of 100 times on the afferent pathway of the arms, from some 18 x 10 6 receptors at the periphery of the suckers to 140000 fibres entering the brain. The brain thus serves for major decisions, whose detailed execution is left to peripheral reflex centres in the arms. The optic nerve fibres are very numerous, and all small (20 x 10 6 , < 1.3 μ m) presumably for economy of space and material. By contrast the static nerves, although they are short, contain a small number of large fibres (1400 between 6 and 22 μ m) as well as several thousand smaller ones. The presence of sets of fibres with their distinctive diameters, conduction velocities and other properties is evidently a fundamental feature of the design of the nervous system of cephalopods as it is of vertebrates, although the significance of many features remains to be explored.