Search

Abstract Glycolate is produced by microalgae under photorespiratory conditions and has the potential for sustainable organic carbon production in biotechnology. This study explores the glycolate production balance in Chlamydomonas reinhardtii, using a custom-built 10-L flat panel bioreactor with sophisticated measurements of process factors such as nutrient supply, gassing, light absorption and mass balances. As a result, detailed information regarding carbon and energy balance is obtained to support techno-economic analyses. It is shown how nitrogen is a crucial element in the biotechnological process and monitoring nitrogen content is vital for optimum performance. Moreover, the suitable reactor design is advantageous to efficiently adjust the gas composition. The oxygen content has to be slightly above 30% to induce photorespiration while maintaining photosynthetic efficiency. The final volume productivity reached 27.7 mg of glycolate per litre per hour, thus, the total process capacity can be calculated to 13 tonnes of glycolate per hectare per annum. The exceptional volume productivity of both biomass and glycolate production is demonstrated, and consequently can achieve a yearly CO2 sequestration rate of 35 tonnes per hectare. Although the system shows such high productivity, there are still opportunities to enhance the achieved volume productivity and thus exploit the biotechnological potential of glycolate production from microalgae.

Glycolate is produced by microalgae under photorespiratory conditions and has the potential for sustainable organic carbon production in biotechnology. This study explores the glycolate production balance in Chlamydomonas reinhardtii, using a custom-built 10-L flat panel bioreactor with sophisticated measurements of process factors such as nutrient supply, gassing, light absorption and mass balances. As a result, detailed information regarding carbon and energy balance is obtained to support techno-economic analyses. It is shown how nitrogen is a crucial element in the biotechnological process and monitoring nitrogen content is vital for optimum performance. Moreover, the suitable reactor design is advantageous to efficiently adjust the gas composition. The oxygen content has to be slightly above 30% to induce photorespiration while maintaining photosynthetic efficiency. The final volume productivity reached 27.7 mg of glycolate per litre per hour, thus, the total process capacity can be calculated to 13 tonnes of glycolate per hectare per annum. The exceptional volume productivity of both biomass and glycolate production is demonstrated, and consequently can achieve a yearly CO2 sequestration rate of 35 tonnes per hectare. Although the system shows such high productivity, there are still opportunities to enhance the achieved volume productivity and thus exploit the biotechnological potential of glycolate production from microalgae. [ABSTRACT FROM AUTHOR]

Introduction: The use of traditional, image intensifier fluoroscopy with a radiopaque grid during direct anterior total hip arthroplasty (DA THA) has demonstrated reduced variability in component positioning and operative time compared to fluoroscopy without a grid. A disadvantage of image intensifier fluoroscopy is spatial distortion, particularly compared to flat-panel fluoroscopy systems. The purpose of this study is to determine whether flat-panel fluoroscopy decreases variability in component positioning during DA THA compared to the use of traditional grid fluoroscopy. Methods: We retrospectively reviewed 70 consecutive DA THAs between February 2020 and February 2021: 36 using flat-panel fluoroscopy, and 34 using traditional fluoroscopy with a grid. Radiographs were independently reviewed by 2 authors to identify components exceeding goal parameters: cup abduction of 40 ± 10 degrees, as well as offset and limb lengths within 10 mm of the contralateral side. Binary values for goal parameter achievement were assigned for each THA. Results: No significant difference was observed in the number of hips that met goals for cup abduction (100% vs 97%, P = 1.00), hip offset (88% vs 88%, P = 1.00), limb length (91% vs 94% [ ±10 mm], P = .669, 65% vs 72% [±5 mm], P = .498), or for the number of hips that met all 3 component goals (79% vs 80%, P = 1.00). No significant difference in operative time was noted between the 2 groups (110.2 minutes vs 100.9, P = .76). Conclusions: We demonstrated no significant difference in component positioning in DA THAs utilizing flat-panel fluoroscopy as compared to using traditional fluoroscopy with a grid.

A non-linear energy-based analytical approach to design flat sandwich panels resistant to bird strike is presented. The approach is then complemented by numerical simulation in Abaqus using smooth particle hydrodynamics to model the bird and a non-linear stress-strain model for the core material. Flat sandwich panels were designed to deform and just fail when the maximum deflections are reached for given strike energies. The panels designed with this approach were tested using gelatin birds and two different material combinations with non-toughened and toughened facesheet and core materials. The analytical and numerical approaches were found to be conservative as they predicted failure onset for the bird energies selected while the tests showed no damage. The maximum deflection and maximum strains at different locations of the panels were well predicted by the numerical analysis, but the predictions departed significantly from the tests after the first peak was reached. [ABSTRACT FROM AUTHOR]

A continuous beam-steering solution for circularly polarized (CP) radial-line slot array (RLSA) antennas is presented and demonstrated with a fabricated prototype. The solution is based on the near-field meta-steering (NFMS) method, which is implemented through a pair of highly transmitting hybrid metasurfaces (HMs) that are placed above a high-gain CP RLSA antenna in the near-field region. Cells in HMs, unlike conventional metasurfaces (CMs), can provide exact or close to exact phase shift with transmission magnitude larger than −1 dB. This is achieved by combining the nonoverlapping phase ranges of two dramatically different phase-shifting cells. The RLSA is stationary, while the two HMs are rotated to steer the beam in a 2-D (azimuth and elevation) space. The measured results of the prototype demonstrate that the system can steer its beam to a maximum elevation angle of 40.6° with a maximum gain of 30.9 dBic. The axial ratio remained less than 3 dB in the 3 dB beamwidth even when the beam is steered. The height of the system is only 4.5 cm, which is much less than mechanically steered reflector antennas. Unlike electronically steered high-gain antenna arrays, this system requires only few watts of power only when rotating HMs and has zero power consumption when the beam is stationary. [ABSTRACT FROM AUTHOR]

Purpose: Interventional procedures involving radionuclides (e.g., radioembolization) would benefit from single‐photon emission computed tomography (SPECT) performed in the intervention room because the activity distribution could be immediately visualized. We believe it might be possible to perform SPECT with the C‐arm cone beam computed tomography (CBCT) scanner present in the intervention room by equipping the x‐ray flat panel detector with a collimator. The purpose of this study is to demonstrate the approach and to investigate the achievable SPECT reconstruction quality. Methods: A proof‐of‐concept experiment was performed to evaluate the possibility of nuclear imaging with an x‐ray flat panel detector. The experiment was digitally replicated to study the accuracy of the simulations. Three flat panel configurations (with standard hardware and reconstruction methodology, with sophisticated reconstruction methodology, and with expected future hardware) and a conventional gamma camera were evaluated. The Jaszczak and the NEMA IQ phantom (filled with 99mTc) were simulated and assessed on resolution and contrast‐to‐noise ratio (CNR). Results: The proof‐of‐concept experiment demonstrated that nuclear images could be obtained from the flat panel detector. The simulation of the same configuration demonstrated that simulations could accurately predict the flat panel detector response. The CNR of the 37 mm sphere in the NEMA IQ phantom was 22.8 ± 1.2 for the gamma camera reconstructions, while it was 11.3 ± 0.7 for the standard flat panel detector. With sophisticated reconstruction methodology, the CNR improved to 13.5 ± 1.4. The CNR can be expected to advance to 18.1 ± 1.3 for future flat panel detectors. Conclusions: The x‐ray flat panel detector of a CBCT scanner might be used to perform nuclear imaging. The SPECT reconstruction quality will be lower than that achieved by a conventional gamma camera. The flat panel detector approach could, however, be useful in providing a cost‐effective alternative to the purchase of a mobile SPECT scanner for enabling interventional scanning. [ABSTRACT FROM AUTHOR]

Flat panel detector (FPD) technology in interventional cardiology is on the increase due to its varied advantages compared to the conventional image intensifier (II) systems. It is not clear whether FPD imparts lower radiation doses compared to II systems though a few studies support this finding. This study intends to compare radiation doses from II and FPD systems for coronaryangiography (CAG) and Percutaneous Transluminal Coronary Angioplasty (PTCA) performed in a tertiary referral center. Radiation doses were measured using dose area product (DAP) meter from patients who underwent CAG (n = 222) and PTCA (n = 75) performed using FPD angiography system. The DAP values from FPD were compared with earlier reported data using II systems from the same referral center where the study was conducted. The mean DAP values from FPD system for CAG and PTCA were 24.35 and 63.64 Gycm 2 and those from II system were 27.71 and 65.44 Gycm 2 . Transition from II to FPD system requires stringent dose optimization strategies right from the initial period of installation.

Solar thermal collectors for buildings use a heat transfer fluid passing through heat exchange channels in the absorber. Flat plate absorbers may pass the fluid through a tube bonded to a thermally conducting plate or achieve lower thermal resistance and pressure drop by using a flooded panel or microchannel design. The pressure drop should be low to minimise power input to the circulating pump. A method is presented for choosing the optimum channel hydraulic diameter subject to geometric similarity and pumping power constraints; this is an important preliminary design choice for any solar collector designer. The choice of pumping power is also illustrated in terms of relative energy source costs. Both microchannel and serpentine tube systems have an optimum passage diameter, albeit for different reasons. Double-pass and flooded panel designs are considered as special microchannel cases. To maintain efficiency, the pumping power per unit area must rise as the passage length increases. Beyond the optimum pumping power the rise in operating cost outweighs the increase in collector efficiency. [ABSTRACT FROM AUTHOR]

The nonlinear static deflections of a functionally graded carbon nanotube (FG-CNT) reinforced flat composite panel are examined under a uniform thermal environment for different end conditions. The temperature-dependent material properties of the matrix and the fiber (carbon nanotubes) are considered in conjunction with the different gradients of carbon nanotube concentrations through the thickness direction. The mathematical model of the carbon nanotube reinforced flat composite panel is formulated for different types of gradients using the Green-Lagrange geometrical strain in the framework of the shear deformable higher-order kinematic theory. Further, the equilibrium equation of the panel is obtained using the variational method and discretized through the finite-element concept. The nonlinear deflections are worked out numerically using the direct iterative method via a suitable computer code. The validation and the convergence performance of the present numerical results were checked. Finally, the significance and inevitability of such a higher-order nonlinear model for the analysis of gradient carbon nanotube structure are established by solving different numerical examples for various parameters (types of grading, aspect ratios, thickness ratios, volume fractions, thermal field, and end conditions) and discussed in detail. [ABSTRACT FROM AUTHOR]

Continuous production of diatom Entomonies sp. was performed in mechanically stirred tank and flat-panel airlift photobioreactors (FPAP). The maximum specific growth rate of diatom from the batch experiment was 0.98 d−1. A series of dilution rate and macronutrient concentration adjustments were performed in a stirred tank photobioreactor and found that the dilution rate ranged from 0.7 to 0.8 d−1 and modified F/2 growth media containing nitrate at 3.09 mg N/L, phosphate at 2.24 mg P/L, and silicate at 11.91 mg Si/L yielded the maximum cell number density. Finally, the continuous cultivation of Entomonies sp. was conducted in FPAP using the optimal conditions determined earlier, resulting in the maximum cell number density of 19.69 × 104 cells/mL, which was approximately 47 and 73% increase from the result using the stirred tank photobioreactor fed with modified and standard F/2 growth media, respectively. [ABSTRACT FROM AUTHOR]

Efficient photosynthetic biomass production in a high rate pond (HRP) or a photobioreactor (PBR) represents the first step of microalgae platforms for the production of renewable fuels, animal feeds and a diverse range of high value products. This study analyses the interplay between solar energy input, ambient temperature and system surface area to volume (SA:V) ratio in terms of photosynthetic performance (yield, areal and volumetric productivity, photon conversion efficiency). Ten pilot scale trials were conducted under subtropical conditions using 2 microalgae strains ( Chlorella sorokiniana and Chlorella sp.) in 5 different cultivation system geometries: HRPs, flat panel PBRs (0.75 m and 1.5 m high) and tubular PBRs (0.74 m and 1.49 m high). The evaluation of culture temperature and biomass productivity response to solar irradiance in the five production systems suggests that the optimal SA:V ratio range lies between 43–73 m 2 m − 3 for C. sorokiniana in non-cooled systems regardless of system geometry under the conditions tested. The overall photosynthetic performance at higher SA:V ratios was improved for Chlorella sp. using temperature regulation. The highest observed daily photon conversion efficiency (PCE) was 4.44% (based on illuminated PBR surface area and total solar spectrum) in the high flat panel PBR using C. sorokiniana (40.8 g m − 2 d − 1 , 0.23 g L − 1 d − 1 ). The highest achieved mean PCE (based on illuminated PBR surface area and total solar spectrum) was 2.5% in the low tubular PBR with Chlorella sp. (24.9 g m − 2 d − 1 , 0.43 g L − 1 d − 1 ). The trial data provides important design principles to help fast track systems optimisation for near optimal sub-tropical conditions. [ABSTRACT FROM AUTHOR]