Effects of Hydrocarbon Additions on Gas-liquid Mass Transfer Coefficients in Biphasic Bioreactors

Silva, Teresa Lopes da,Calado, Vitor,Silva, Nadia,Mendes, Rui L.,Alves, Sebastiao S.,Vasconcelos, Jorge M.T.,Reis, Alberto The Korean Society for Biotechnology and Bioengine 2006 Biotechnology and Bioprocess Engineering Vol.11 No.3

The effects of aliphatic hydrocarbons (n-hexadecane and n-dodecane) on the volumetric oxygen mass transfer coefficient $(k_L\;a)$ were studied in flat alveolar airlift reactor and continuous stirred tank reactors (CSTRs). In the flat alveolar airlift reactor, high aeration rates (>2vvm) were required in order to obtain efficient organic-aqueous phase dispersion and reliable $k_La$ measurements. Addition of 1% (v/v) n-hexadecane or n-dodecane increased the $k_La$ 1.55- and 1.33-fold, respectively, compared to the control (superficial velocity: $25.8{\times}10^{-3}m/s$, sparger orifice diameter: 0.5 mm). Analysis of the gas-liquid interfacial area a and the liquid film mass transfer coefficient $k_L$ suggests that the observed $k_La$ increase was a function of the media's liquid film mass transfer. Addition of 1% (v/v) n-hexadecane or n-dodecane to analogous setups using CSTRs led to a $k_La$ increase by a factor of 1.68 and 1.36, respectively (superficial velocity: $2.1{\times}10^{-3}m/s$, stirring rate: 250 rpm). These results propose that low-concentration addition of oxygen-vectors to aerobic microbial cultures has additional benefit relative to incubation in purely aqueous media.

Tibial-graft fixation methods on anterior cruciate ligament reconstructions: a literature review

( Vitor Luis Pereira ),( João Victor Medeiros ),( Gilvan Rodrigues Silva Nunes ),( Gabriel Taniguti De Oliveira ),( Alexandre Pedro Nicolini ) 대한슬관절학회 2021 대한슬관절학회지 Vol.33 No.-

Introduction: Anterior cruciate ligament (ACL) reconstruction is the most performed orthopedic surgical procedure. The result of ACL reconstructions depends on multiple technical variables, including tension to be applied to the graft for fixation, knee-flexion angle during fixation and the type of fixation to the bone. Objective: To carry out a survey of the literature with the best evidence on these themes. Methods: Literature review about methods of tibial-graft fixation in ACL reconstructions - tension applied at the time of fixation, type of graft fixation, and knee-flexion degree during tibial fixation. Results: Thirty studies on the selected topics were found. Most studies point to graft-tension levels close to 90 N to obtain the best results. Regarding the knee-flexion angle, multiple studies suggest that fixation at a 30° angle would bring superior biomechanical advantages. Regarding the type of implant for fixation, it is not possible to affirm the superiority of one method over another in clinical outcomes. Conclusions: There is no consensus on the best method for tibial fixation of the grafts in ACL reconstructions regarding tension, type of implant and knee-flexion angle. However, the analysis of the studies pointed to certain trends and allowed the drawing of specific conclusions.

Single-Stage Double-Buck Topologies with High Power Factor

Vitor Fernao Pires,Jose Fernando Silva 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.5

This paper presents two topologies for single-stage single-phase double-buck type PFC converters, designed to operate at high power factor, near sinusoidal input currents and adjustable output voltage. Unlike the known buck type PFC topologies, in which the output voltage is always lower than the maximum input voltage, the proposed converters can operate at output voltages higher than the ac input peak voltage. A reduced number of switches on the main path of the current are another characteristic of the two proposed topologies. To shape the input line currents, a fast and robust controller based on a sliding mode approach is proposed. This active non-linear control strategy, applied to these converters allows high quality input currents. A Proportional Integral (PI) controller is adopted to regulate the output voltage of the converters. This external voltage controller modulates the amplitude of the sinusoidal input current references. The performances of the presented rectifiers are verified with experimental results.

State of the Art of Biodegradable Nanofluids Application in Machining Processes

Vitor Baldin,Leonardo Rosa Ribeiro da Silva,Alisson Rocha Machado,Celso Ferraz Houck 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.5

For ecological and health issues of those involved in the manufacturing, usage, handling, and disposal of cutting fluids, research has been developed for scientific and technological advances in biodegradable cutting fluids, application methods, and solid nanolubricants. Using a minimum quantity of lubricant (MQL) in machining processes proved to be a viable alternative to replacing low-pressure jet machining. Nanoparticles from 5 to 100 nm in size are usually dispersed in vegetable-based cutting fluid; this combination improves the tribological properties of the nanofluid and the machinability of metal alloys like steel, titanium, nickel, and aluminum alloys, with reduced cutting forces, cutting temperature, tool wear and workpiece surface roughness. This work aims to present an updated summary of the lubrication and cooling action provided by using the MQL technique, biodegradable cutting fluids applied by MQL, the use of nanoparticles added to the cutting fluids, and the physical properties of nanoparticles, tribological characteristics, and the behavior of the nanofluids. The changes in machining force, cutting temperature, surface integrity, and wear of cutting tools with biodegradable nano-cutting fluids are also focused on. The use of nanoparticles in cutting fluids associated with MQL application has shown an increase in the lubricating and coolant properties of cutting fluids, which contribute to the reduction of machining force, cutting temperature, workpiece surface roughness, coefficient of friction, and wear of cutting tools. Thus, the results of this summary can provide theoretical support and experimental guidance for exploring the lubricating and cooling properties and the mechanism present in film formation with nanofluids at the chip-too-workpiece interfaces. Knowledge of such phenomena helps to popularize an eco-friendly practice in metal-mechanic industries.

Single-Stage Double-Buck Topologies with High Power Factor

Pires, Vitor Fernao,Silva, Jose Fernando The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.5

This paper presents two topologies for single-stage single-phase double-buck type PFC converters, designed to operate at high power factor, near sinusoidal input currents and adjustable output voltage. Unlike the known buck type PFC topologies, in which the output voltage is always lower than the maximum input voltage, the proposed converters can operate at output voltages higher than the ac input peak voltage. A reduced number of switches on the main path of the current are another characteristic of the two proposed topologies. To shape the input line currents, a fast and robust controller based on a sliding mode approach is proposed. This active non-linear control strategy, applied to these converters allows high quality input currents. A Proportional Integral (PI) controller is adopted to regulate the output voltage of the converters. This external voltage controller modulates the amplitude of the sinusoidal input current references. The performances of the presented rectifiers are verified with experimental results.

Establishment and Partial Characterization of an Epirubicin-Resistant Gastric Cancer Cell Line with Upregulated ABCB1

Felipe, Aledson Vitor,Moraes, Andrea Aparecida,de Oliveira, Juliana,da Silva, Tiago Donizetti,Forones, Nora Manoukian Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.16

Multidrug resistance (MDR) is a major impediment to successful chemotherapy of gastric cancer. Our aim was to establish an epirubicin-resistant cell subline (AGS/EPI) and to elucidate the mechanisms involved in acquired EPI resistance. The AGS/EPI cell subline developed by exposing parental AGS cells to stepwise increasing concentrations of EPI demonstrated 2.52-fold resistance relative to the AGS cell line, and mRNA expression of the ATP-dependent drug-efflux pump P-glycoprotein (Pgp), more recently known as ABCB1 protein, was similarly upregulated. An AGS/EPI cell subline could thus be effectively established, and MDR mechanism of these cells was shown to be related to the overexpression of mRNA of the ABCB1 gene.

Focal Dermal Hypoplasia (Goltz Syndrome): A Case Report Showing a Wide Variety of Systemic and Oral Manifestations

Átila Vinícius Vitor Nobre,Mário Taba Júnior,Alfredo Ribeiro Silva,Sérgio Luís Scombatti de Souza,Ana Carolina Fragoso Motta 대한피부과학회 2022 Annals of Dermatology Vol.34 No.4

Focal dermal hypoplasia (FDH), also known as Goltz syndrome, consists of an unusual genodermatosis that affects tissues of ectodermal and mesodermal origin and various or- gans and systems, especially skin, bones, eyes, and oral cavity. While systemic manifesta- tions of FDH have been well documented, the oral manifestations have not been extensively discussed. We present a 22-year-old female patient with history of FDH that showed a variety of systemic and oral manifestations. FDH was diagnosed at birth based on cutane- ous alterations. Extra and intraoral examination showed facial asymmetry, lip and perioral atrophy, upper lip papilloma, malocclusion, enamel hypoplasia, and gingival hyperplasia. Mucosal lesions, periodontal diseases, and malocclusion were treated by oral surgery, peri- odontal therapy and orthodontic treatment, respectively. Although FDH is an uncommon syndrome, health professionals should be aware of its systemic and oral manifestations to establish an early diagnosis and adequate treatment.

RNA Interference: a Promising Therapy for Gastric Cancer

Felipe, Aledson Vitor,Oliveira, Juliana de,Chang, Paula Yun Joo,Moraes, Andrea Aparecida de Fatima Souza,Silva, Tiago Donizetti da,Tucci-Viegas, Vanina Monique,Forones, Nora Manoukian Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.14

Gastric cancer (GC) remains a virtually incurable disease when metastatic and requires early screening tools for detection of early tumor stages. Therefore, finding effective strategies for prevention or recurrence of GC has become a major overall initiative. RNA-interference (RNAi) is an innovative technique that can significantly regulate the expression of oncogenes involved in gastric carcinogenesis, thus constituting a promising epigenetic approach to GC therapy. This review presents recent advances concerning the promising biomolecular mechanism of RNAi for GC treatment.

Magnitude Modulation for VSAT’s Low Back-Off Transmission

Marco Gomes,Francisco Cercas,Vitor Silva,Martin Tomlinson 한국통신학회 2010 Journal of communications and networks Vol.12 No.6

This paper addresses the problem of controlling the envelope’s power peak of single carrier modulated signals, band limited by root-raised cosine (RRC) pulse shaping filters, in order to reduce power amplifier back-off for very small aperture terminals ground stations. Magnitude modulation (MM) is presented as a very efficient solution to the peak-to-average power ratio problem. This paper gives a detailed description of the MM concept and its recent evolutions. It starts by extending the look-up-table (LUT)based approach of the MM concept to M-ary constellations with M ≤ 16. The constellation and RRC symmetries are explored,allowing considerable reduction on LUT computation complexity and storage requirements. An effective multistage polyphase (MPMM) approach for the MM concept is then proposed. As opposed to traditional LUT-MM solutions, MM coefficients are computed in real-time by a low complexity multirate filter system. The back-off from high-power amplifier saturation is almost eliminated (reduction is greater than 95%) with just a 2-stage MPMMsystem even for very demanding roll-off cases (e.g., α = 0.1). Also, the MPMM is independent of modulation in use, allowing its easy application to constellations withM>16.

Tomographic Study of Femoral Positioning in Anterior Cruciate Ligament Reconstruction Using the Transtibial Technique

( Robson Rocha Da Silva ),( Marcos Almeida Matos ),( Valonie Carlos Neves Brasileiro Costa ),( Vitor Hugo Abreu Azevedo De Morais ),( Luiz Eduardo Lago De Castro ) 대한슬관절학회 2017 대한슬관절학회지 Vol.29 No.3

Purpose: To analyze the location of the femoral tunnel by three-dimensional computed tomography (3D CT) of the lateral condyle in patients who underwent arthroscopic single-bundle anterior cruciate ligament (ACL) reconstruction, performed using a modified transtibial technique, and to compare the results with data from the literature. Materials and Methods: Seventeen patients with ACL lesions underwent modified transtibial ACL reconstruction. Postoperatively, 3D CT examinations were performed and the images were analyzed by the quadrant system described by Bernard and Hertel to define the femoral tunnel coordinates. Results: The mean value of femoral tunnel location coordinates was 37.1±5.9 in the horizontal plane and 23.9±7.5 in the vertical plane. Compared with other studies using the transtibial or transportal technique, femoral positioning was improved in the vertical plane. The outside-in technique provided the best results both in the vertical and horizontal planes. Conclusions: The modified transtibial technique was not effective for systematically anatomic femoral tunnel positioning; however, it was relatively better than the conventional transtibial technique.