Algal biofuels: Challenges and opportunities Leite, Gustavo B.; Abdelaziz, Ahmed E.M.; Hallenbeck, Patrick C.
Bioresource technology,
10/2013, Letnik:
145
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
► Algae are promising for biofuels production. ► Higher productivity and lipid content than plants. ► Open ponds are better than PBRs for biofuels. ► Technical hurdles include harvesting and oil ...extraction.
Biodiesel production using microalgae is attractive in a number of respects. Here a number of pros and cons to using microalgae for biofuels production are reviewed. Algal cultivation can be carried out using non-arable land and non-potable water with simple nutrient supply. In addition, algal biomass productivities are much higher than those of vascular plants and the extractable content of lipids that can be usefully converted to biodiesel, triacylglycerols (TAGs) can be much higher than that of the oil seeds now used for first generation biodiesel. On the other hand, practical, cost-effective production of biofuels from microalgae requires that a number of obstacles be overcome. These include the development of low-cost, effective growth systems, efficient and energy saving harvesting techniques, and methods for oil extraction and conversion that are environmentally benign and cost-effective. Promising recent advances in these areas are highlighted.
•The worldwide COVID-19 pandemic has heavily hit small tourism enterprises.•Resilience directly and indirectly influence sustainable tourism development.•Performance mediates relationship between ...resilience and sustainable development.•Enterprise type significantly affect the results and the research model.•Small restaurant owner-managers showed more resilience than their hotel counterpart.
Tourism is one of the hardest-hit industries by the global pandemic of Novel Coronavirus (COVID-19). Small tourism enterprises have been heavily affected and have had difficulty in business recovery. This research is an early attempt to explore the direct impact of small hospitality enterprises’ resilience on sustainable tourism development as well as indirect impact through performance. A pre-tested questionnaire survey was self-administered to owner-managers of small hospitality enterprises in Greater Cairo, Egypt. The results of structural equation modeling (SEM) using AMOS showed a positive, direct, and significant impact of resilience (planned and adaptive) on sustainable tourism development and indirect influence through performance. The results of the multi-group analysis showed that enterprise type has a significant effect on the results, where restaurant owner-managers expressed more resilience than their hotel counterparts. Several theoretical (for scholars) and practical implications for tourism policy-makers and owner-managers have been discussed and elaborated.
Biodiesel production from microalgae lipids is being considered as a potential source of renewable energy. However, practical production processes will probably require the use of local strains ...adapted to prevailing climatic conditions. This report describes the isolation of 100 microalgal strains from freshwater lakes and rivers located in the vicinity of Montreal, Quebec, Canada. Strains were identified and surveyed for their growth on secondary effluent from a municipal wastewater treatment plant (La Prairie, QC, Canada) using a simple and high throughput microalgal screening method employing 12 well plates. The biomass and lipid productivity of these strains on wastewater were compared to a synthetic medium under different temperatures (10±2°C and 22±2°C) and a number identified that showed good growth at 10°C, gave a high lipid content (ranging from 20% to 45% of dry weight) or a high capacity for nutrient removal.
•Indigenous strains were screened for utilization of glycerol and xylose.•Yields of lipids and biomass are likely to be improved in future optimization studies.•Lipid productivity from glycerol of ...some was higher than previously reported.•One strain gained increased biomass in the light with both xylose and glycerol.•For the first time xylose utilization by a microalga is shown.
Microalgae are a promising alternative for sustainable biofuel production, but production yields and costs present a significant bottleneck. Here, the use of glycerol and xylose to boost the lipid yield was evaluated using ten strains from the Université de Montréal collection of microalgae. This report shows that some microalgal strains are capable of mixotrophic and heterotrophic growth on xylose, the major carbon source found in wastewater streams from pulp and paper industries, with an increase in growth rate of 2.8-fold in comparison to photoautotrophic growth, reaching up to μ=1.1/d. On glycerol, growth rates reached as high as μ=1.52/d. Lipid productivity increased up to 370% on glycerol and 180% on xylose for the strain LB1H10, showing the suitability of this strain for further development of biofuels production through mixotrophic cultivation.
Over the last couple of decades, the advancement in Microelectromechanical System (MEMS) devices is highly demanded for integrating the economically miniaturized sensors with fabricating technology. ...A sensor is a system that detects and responds to multiple physical inputs and converting them into analogue or digital forms. The sensor transforms these variations into a form which can be utilized as a marker to monitor the device variable. MEMS exhibits excellent feasibility in miniaturization sensors due to its small dimension, low power consumption, superior performance, and, batch-fabrication. This article presents the recent developments in standard actuation and sensing mechanisms that can serve MEMS-based devices, which is expected to revolutionize almost many product categories in the current era. The featured principles of actuating, sensing mechanisms and real-life applications have also been discussed. Proper understanding of the actuating and sensing mechanisms for the MEMS-based devices can play a vital role in effective selection for novel and complex application design.
PurposeIn light of the current challenges in the business environment, firms, particularly those involved in supply chains, must foster innovation. In this context, the current study employs the ...theory of dynamic organizational capabilities (DOCs) to track supply chain learning capabilities (SCLCs) and independently uncover their relationship to innovation at both the product and process levels. Similarly, the study intends to investigate the influence of technological turbulence (TT) on these relationships as a moderating variable.Design/methodology/approachThe data were gathered using in-person interviews with 189 CEOs with some supply chain management proficiency from small and medium-sized enterprises (SMEs) in the industrial zones of eastern Egypt. The study used a survey approach to collect data, and the SEM-PLS technique was utilized to analyze the data.FindingsStudy findings revealed that SCLCs positively affect product and process innovation. In addition, TT positively moderates the relationship between SCLCs and product and process innovation, except for risk-taking capability. Further theoretical and practical implications are derived from the study findings.Originality/valueThis research adds to the knowledge of the dynamic capabilities theory (DCT), which affects how firms interact with their external environment. Studying learning capabilities are employed as essential competencies to counterbalance high levels of TT in the external environment in terms of innovative performance and vice versa if firms do not attempt to strengthen their dynamic learning capabilities in supply chains. In addition, this study contributes to the literature by studying learning capabilities from the external perspective, where SCLCs are being developed as a new variable to improve innovation.
A time latch for high speed time‐based ADCs Abdelaziz, Ahmed; Musah, Tawfiq
Electronics letters,
July 2022, 2022-07-00, 20220701, 2022-07-01, Letnik:
58, Številka:
14
Journal Article
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This letter presents a novel time latch for high speed time domain analogue to digital converters. The time latches reported in literature suffer from a limited maximum operating frequency, which ...makes them unsuitable for high frequency applications. Analysis of the proposed time latch shows it can operate at 10 GHz, 2.5x higher than the best reported time latch. Furthermore, simulations in 28 nm CMOS technology confirm that the enhancement in the speed of the proposed time latch comes with low overhead in area and power. Potential design issues with the proposed time latch are also discussed.
This study was conducted to compare two management protocols for post-partum hemorrhage (PPH) during cesarean section (CS) in placenta previa (PP), Bakri balloon protocol versus non-balloon protocol. ...Secondary analysis among balloon treated cases was also performed to identify predictors of success, failure or complications, if any.
A prospective cohort study was conducted in two hospitals in Saudi Arabia, including cases that developed PPH during CS for PP. The primary outcome measure was success in preventing hysterectomy, while secondary outcome measures were amount of blood loss, need for blood transfusion, need for return to theater and admission to intensive care unit.
One hundred and fifty-one cases were identified as low-lying placenta and PP, of which 114 developed PPH. Two patients were unstable and required immediate hysterectomy. The remaining 112 cases were managed by balloon (72 cases) or non-balloon protocols (40). The balloon alone was successful in achieving hemostasis in 87.5% of cases. When analyzed specifically, balloon success was associated with the absence of accreta (odds ratio 0.001, confidence interval 0.000-0.974) and short operation duration (odds ratio 1.143, confidence interval 1.018-1.282).
Application of the Bakri balloon for the management of PPH after CS in cases of PP is an effective strategy that should be affordable worldwide.
Cabozantinib is a small molecule tyrosine kinase inhibitor that initially showed activity in medullary thyroid cancer and was recently approved by the Food and Drug Administration for the treatment ...of metastatic renal cell carcinoma after progression on first line therapy. Areas covered: In the METEOR trial, cabozantinib demonstrated significantly improved efficacy in all three endpoints; response rates, progression free survival and overall survival in a randomized trial with everolimus as an active comparator. Cabozantinib also showed activity in the front line setting in RCC within the CABOSUN trial. The study randomized untreated metastatic RCC patients to either cabozantinib or sunitinib and the former showed improved progression free survival which was the primary endpoint. The future holds promise for indications in other malignancies, given the preliminary efficacy and unique mechanism of action of cabozantinib. In this review we address the mechanism of action, pharmacodynamics and pharmacokinetics of cabozantinib, and also review the development pathway of this agent in the treatment of advanced renal cell carcinoma. The potential benefit in specific patient populations, such as poor risk patients and bone metastases subgroups is also discussed. Expert commentary: The clinical applications of cabozantinib will be addressed within the context of the current competitive therapeutic landscape of RCC.
Over the last few years, biopolymers have attracted great interest in tissue engineering and regenerative medicine due to the great diversity of their chemical, mechanical, and physical properties ...for the fabrication of 3D scaffolds. This review is devoted to recent advances in synthetic and natural polymeric 3D scaffolds for bone tissue engineering (BTE) and regenerative therapies. The review comprehensively discusses the implications of biological macromolecules, structure, and composition of polymeric scaffolds used in BTE. Various approaches to fabricating 3D BTE scaffolds are discussed, including solvent casting and particle leaching, freeze-drying, thermally induced phase separation, gas foaming, electrospinning, and sol-gel techniques. Rapid prototyping technologies such as stereolithography, fused deposition modeling, selective laser sintering, and 3D bioprinting are also covered. The immunomodulatory roles of polymeric scaffolds utilized for BTE applications are discussed. In addition, the features and challenges of 3D polymer scaffolds fabricated using advanced additive manufacturing technologies (rapid prototyping) are addressed and compared to conventional subtractive manufacturing techniques. Finally, the challenges of applying scaffold-based BTE treatments in practice are discussed in-depth.
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