Recurrent herpes simplex infections: laser therapy as a potential tool for long-term successful treatment

Herpes simplex virus types 1 and 2 are the main infectious agents associated with oral and genital ulcerations. These infections are now widely recognized as sexually transmitted diseases. Among treatment options, low-level laser therapy (LLLT) has shown promising clinical results as a longer-lasting suppression therapy. Two clinical cases are described with recurrent labial herpes for which LLLT was used. Following treatment, both patients remained symptom free during the 17-month clinical follow-up period.

Characterization of an OPCPA laser amplifier based on the nonlinear crystal YCOB

The work described in this thesis was performed at the Laboratory for Intense Lasers (L2I) of Instituto Superior Técnico, University of Lisbon (IST-UL). Its main contribution consists in the feasibility study of the broadband dispersive stages for an optical parametric chirped pulse amplifier based on the nonlinear crystal yttrium calcium oxi-borate (YCOB). In particular, the main goal of this work consisted in the characterization and implementation of the several optical devices involved in pulse expansion and compression of the amplified pulses to durations of the order of a few optical cycles (20 fs). This type of laser systems find application in fields such as medicine, telecommunications and machining, which require high energy, ultrashort (sub-100 fs) pulses. The main challenges consisted in the preliminary study of the performance of the broadband amplifier, which is essential for successfully handling pulses with bandwidths exceeding 100 nm when amplified from the μJ to 20 mJ per pulse. In general, the control, manipulation and characterization of optical phenomena on the scale of a few tens of fs and powers that can reach the PW level are extremely difficult and challenging due to the complexity of the phenomena of radiation-matter interaction and their nonlinearities, observed at this time scale and power level. For this purpose the main dispersive components were characterized in detail, specifically addressing the demonstration of pulse expansion and compression. The tested bandwidths are narrower than the final ones, in order to confirm the parameters of these elements and predict the performance for the broadband pulses. The work performed led to additional tasks such as a detailed characterization of laser oscillator seeding the laser chain and the detection and cancelling of additional sources of dispersion.

Recuperação renovável de Mg a partir de MgO através da utilização concertada de laser solar e de concentrador solar

Apesar do elevado potencial do metal magnésio como material útil em várias áreas cien-tíficas e tecnológicas, os seus métodos de produção tradicionais têm um impacto fortemente prejudicial no ambiente e um custo elevado. Este facto é um incentivo à procura de novas so-luções, nomeadamente as que recorrem à utilização da radiação solar partindo do óxido de magnésio. Alguns estudos têm já sido feitos nesse sentido, utilizando laser solar ou radiação solar concentrada mas a utilização concertada dos dois não tinha sido feita até ao momento. Neste trabalho, a exequibilidade da utilização concertada destes dois métodos será avaliada e será estudado o comportamento do óxido de magnésio face à radiação que nele incide.

Melhoramento e automatização de um sistema de revestimento com laser

O revestimento com laser permite criar revestimentos localizados pela adição de uma liga similar ou dissimilar. O revestimento visa melhorar as características da superfície metálica, tais como a dureza, a resistência ao desgaste por atrito, à corrosão e à fadiga térmica dos componentes sujeitos a condições adversas de trabalho por prolongados períodos de tempo. Esta dissertação tem como objetivo o melhoramento da configuração, a automatização do sistema de revestimento com laser do Laboratório de Laser do Instituto Superior Técnico (IST) da Universidade de Lisboa, utilizado pelo Centro de Física e Engenharia de Materiais Avançados do Instituto Superior Técnico – CeFEMA e a realização de ensaios de deposições com o fim de validação. Foram estudadas as configurações possíveis para o sistema de posicionamento da amostra, do laser e a configuração para o posicionamento com precisão do bocal de adição de pós ao banho de fusão. Após este estudo foram apresentadas e implementadas as propostas de melhoria do sistema inicial. Para tornar o sistema funcional, foi desenvolvido um controlador para comandar as três guias motorizadas de movimento linear OWIS, o laser IPG YLR e o alimentador de pós PLASMA-TECHNIK. Para simplificar a utilização aos investigadores do CeFEMA foi ainda desenvolvida uma interface gráfica que permite ao utilizador definir os principais parâmetros do processo Para a validação do trabalho desenvolvido foram realizados diversos ensaios de deposição da liga Ti52Ta num substrato de titânio. Através dos ensaios de deposição foi estudada a influência de alguns parâmetros do processo na geometria do revestimento obtido, como a altura, a profundidade, o ângulo do cordão, a diluição entre o material de adição e o substrato, tendo ainda sido estudada a influência dos parâmetros do processo na eficiência de deposição.

Development of an experimental setup for metal cutting research

Analytical, numerical and experimental models have been developed over time to try to characterize and understand the metal cutting process by chip removal. A true knowledge of the cutting process by chip removal is required by the increasing production, by the quality requirements of the product and by the reduced production time, in the industries in which it is employed. In this thesis an experimental setup is developed to evaluate the forces and the temperature distribution in the tool according to the orthogonal cutting model conditions, in order to evaluate its performance and its possible adoption in future works. The experimental setup is developed in a CNC lathe and uses an orthogonal cutting configuration, in which thin discs fixed onto a mandrel are cut by the cutting insert. In this experimental setup, the forces are measured by a piezoelectric dynamometer while temperatures are measured by thermocouples placed juxtaposed to the side face of the cutting insert. Three different solutions are implemented and evaluated for the thermocouples attachment in the cutting insert: thermocouples embedded in thermal paste, thermocouples embedded in copper plate and thermocouples brazed in the cutting insert. From the tests performed in the experimental setup it is concluded that the adopted forces measurement technique shows a good performance. Regarding to the adopted temperatures measurement techniques, only the thermocouples brazed in the cutting insert solution shows a good performance for temperature measurement. The remaining solutions show contact problems between the thermocouple and the side face of the cutting insert, especially when the vibration phenomenon intensifies during the cut. It is concluded that the experimental setup does not present a sufficiently robust and reliable performance, and that it can only be used in future work after making improvements in the assembly of the thermocouples.

Building 3D City Models: Testing and Comparing Laser Scanning and Low-Cost UAV Data Using FOSS Technologies

Contém resumo

Computed tomography-guided cutting needle biopsy of pulmonary lesions

PURPOSE: To report the experience of a radiology department in the use of computed tomography - guided cutting needle biopsy of pulmonary nodules, by evaluating diagnostic yield and incidence of complications. METHODS: This is a retrospective analysis of 52 consecutive patients who underwent lung lesion biopsy guided by computed tomography, performed between May 1997 and May 2000. Thirty-five patients were male and 17 were female, with ages ranging from 5 to 85 years (median, 62 years). The size of the lesions ranged from 1.8 to 15 cm (median, 5.4 cm). RESULTS: In a total of 52 biopsies of lung lesions, 51 biopsies (98.1%) supplied appropriate material for histopathological diagnosis, with 9 diagnosed (17.3%) as benign and 42 (80.8%) as malignant lesions. Specific diagnosis was obtained in 44 (84.6%) biopsies: 4 benign (9.1%) and 40 (90.9%) malignant lesions. The sensitivity, specificity, and accuracy of the cutting needle biopsies for determining presence of malignancy were 96.8%, 100%, and 97.2%, respectively. Complications occurred in 9 cases (17.3%), including 6 cases (11.5%) of small pneumothorax, 1 (1.9%) of hemoptysis, 1 (1.9%) of pulmonary hematoma, and 1 (1.9%) of thoracic wall hematoma. All had spontaneous resolution. There were no complications requiring subsequent intervention. CONCLUSION: The high sensitivity and specificity of the method and the low rate of complications have established cutting needle biopsy as an efficient and safe tool for the diagnosis of lung lesions. In our hospital, cutting needle biopsy is considered a reliable procedure for the evaluation of indeterminate pulmonary nodules.

Computed tomography-guided biopsy of mediastinal lesions: fine versus cutting needles

PURPOSE: To report the experience of a radiology department in the use of computed tomography guided biopsies of mediastinal lesions with fine and cutting needles, describing the differences between them. The results of adequacy of the sample and histologic diagnoses are presented according to the type of needle used. METHODS: We present a retrospective study of mediastinal biopsies guided by computed tomography performed from January 1993 to December 1999. Eighty-six patients underwent mediastinal biopsy in this period, 37 with cutting needles, 38 with fine needles, and 11 with both types (total of 97 biopsies). RESULTS: In most cases, it was possible to obtain an adequate sample (82.5%) and specific diagnosis (67.0%). Cutting-needle biopsy produced a higher percentage of adequate samples (89.6% versus 75.5%, P = 0.068) and of specific diagnosis (81.3% versus 53.1%, P = 0.003) than fine-needle biopsy. There were no complications that required intervention in either group. CONCLUSION: Because they are practical, safe, and can provide accurate diagnoses, image-guided biopsies should be considered the procedure of choice in the initial exploration of patients with mediastinal masses. In our experience, cutting needles gave higher quality samples and diagnostic rates. We recommend the use of cutting needles as the preferred procedure.

Welle tecnologia laser internationalization analysis US market

Welle Laser is a Brazilian company that manufactures marking and engraving machines mainly for large-scale industry segments providing solutions that help increase productivity. Welle laser has 60% market share in Brazil and decided to go internationally in 2015, mainly to increase revenues and diversify business risks. Welle opened an office in Switzerland and celebrated a contract with a Mexican company to distribute their machines in Mexico. The next step for Welle is expanding its operation to USA. In my project I accessed the viability and reasons to enter the US market, the region where Welle should start its operation, and the best entry mode strategy.

Otimização dos parâmetros de processamento em Laser Melting

Dissertação de mestrado integrado em Engenharia Mecânica

Surface plasmon resonance-coupled photoluminescence and resistive switching behavior of pulsed laser-deposited Ag:SiC nanocermet thin films

In this study, Ag:SiC nanocermets were prepared via rapid thermal annealing (RTA) of pulsed laser-deposited SiC/Ag/SiC trilayers grown on Si substrate. Atomic force microscope images show that silver nanoparticles (Ag NPs) are formed after RTA, and the size of NPs increases with increasing Ag deposition time (t Ag). Sharp dip observed in the reflectance spectra confirmed the existence of Ag surface plasmons (SPs). The infrared transmission spectra showed an intense and broad absorption band around 780–800 cm−1 that can be assigned to Si-C stretching vibration mode. Influence of t Ag on the spectral characteristics of SP-enhanced photoluminescence (PL) and electrical properties of silicon carbide (SiC) films has been investigated. The maximum PL enhancement by 5.5 times for Ag:SiC nanocermets is achieved when t Ag ≈ 50 s. This enhancement is due to the strong resonant coupling between SiC and the SP oscillations of the Ag NPs. Presence of Ag NPs in SiC also induces a forming-free resistive switching with switching ratio of 2 × 10−2. The analysis of I–V curves demonstrates that the trap-controlled space-charge-limited conduction with filamentary model is the governing mechanism for the resistive switching in nanocerment thin films.

Structural, optical and magnetic properties of pulsed laser deposited Co-doped ZnO films

Zn1−xCoxO films with different Co concentrations (with x=0.00, 0.10, 0.15, and 0.30) were grown by pulsed laser deposition (PLD) technique. The structural and optical properties of the films were investigated by grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy and photoluminescence (PL). The magnetic properties were measured by conventional magnetometry using a SQUID and simulated by ab-initio calculations using Korring–Khon–Rostoker (KKR) method combined with coherent potential approximation (CPA). The effect of Co-doping on the GIXRD and Raman peaks positions, shape and intensity is discussed. PL studies demonstrate that Co-doping induces a decrease of the bandgap energy and quenching of the UV emission. They also suggest the presence of Zn interstitials when x≥0.15. The 10% Co-doped ZnO film shows ferromagnetism at 390 K with a spontaneous magnetic moment ≈4×10−5 emu and coercive field ≈0.17 kOe. The origin of ferromagnetism is explained based on the calculations using KKR method.

Light-controlled resistive switching in laser-assisted annealed Ba0.8Sr0.2TiO3 thin films

In this work, Ba0.8Sr0.2TiO3 (BST)/ITO structures were grown on glass substrate and laser assisted annealing (LAA) was performed to promote the crystallization of BST. Atomic force microscopy and X-ray diffraction studies confirm the crack free and polycrystalline perovskite phase of BST. White light controlled resistive switching (RS) effect in Au/BST/ITO device is investigated. The device displays the electroforming-free bipolar RS characteristics and are explained by the modulationof the width and height of barrier at the BST/ITO interface via ferroelectric polarization. Moreover, the RS effect is signifi- cantly improved under white light illumination compared to that in the dark. The enhanced RS and photovoltaic effects are explained by considering depolarization field and charge distribution at the interface. The devices exhibit stable retention characteristics with low currents (mA), which make them attractive for non volatile memory devices.

Comparing different methods to measure biofilm thickness: the techniques are: optical coherence tomography, confocal laser scanning microscopy and low load compression test

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Engenharia Clínica)

Transmyocardial laser revascularization. Early clinical experience

OBJECTIVE: To analyze the initial clinical experience of transmyocardial laser revascularization (TMLR) in patients with severe diffuse coronary artery disease. METHODS: Between February, 1998 and February, 1999, 20 patients were submitted to TMLR at the Heart Institute (InCor), University of São Paulo Medical School, Brazil, isolated or in association with conventional coronary artery bypass graft (CABG). All patients had severe diffuse coronary artery disease, with angina functional class III/IV (Canadian Cardiovascular Society score) unresponsive to medical therapy. Fourteen patients were submitted to TMLR as the sole therapy, whereas 6 underwent concomitant CABG. Fifty per cent of the patients had either been previously submitted to a CABG or to a percutaneous transluminal coronary angioplasty (PTCA). Mean age was 60 years, ranging from 45 to 74 years. RESULTS: All patients had three-vessel disease, with normal or mildly impaired left ventricular global function. Follow-up ranged from 1 to 13 months (mean 6.6 months), with no postoperative short or long term mortality. There was significant symptom improvement after the procedure, with 85% of the patients free of angina, and the remaining 15 % of the patients showing improvement in functional class, as well as in exercise tolerance. CONCLUSION: This novel technique can be considered a low risk alternative for a highly selected group of patients not suitable for conventional revascularization procedures.