There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Heterotrophic cultures of microalgae: Metabolism and potential products

Microalgae have recently attracted considerable interest worldwide, due to their extensive application potential in the renewable energy, biopharmaceutical, and nutraceutical industries. Microalgae are renewable, sustainable, and economical sources of biofuels, bioactive medicinal products, and food ingredients. Several microalgae species have been investigated for their potential as value-added products with remarkable pharmacological and biological qualities. As biofuels, they are a perfect substitute to liquid fossil fuels with respect to cost, renewability, and environmental concerns. Microalgae have a significant ability to convert atmospheric CO2 to useful products such as carbohydrates, lipids, and other bioactive metabolites. Although microalgae are feasible sources for bioenergy and biopharmaceuticals in general, some limitations and challenges remain, which must be overcome to upgrade the technology from pilot-phase to industrial level. The most challenging and crucial issues are enhancing microalgae growth rate and product synthesis, dewatering algae culture for biomass production, pretreating biomass, and optimizing the fermentation process in case of algal bioethanol production. The present review describes the advantages of microalgae for the production of biofuels and various bioactive compounds and discusses culturing parameters.

https://link.springer.com/content/pdf/10.1186/s12934-018-0879-x.pdf

The promising future of microalgae: current status, challenges, and optimization of a sustainable and renewable industry for biofuels, feed, and other products

Dual role of microalgae: Phycoremediation of domestic wastewater and biomass production for sustainable biofuels production

Technoeconomic Assessment of Large‐Scale Production of Bioethanol from Microalgal Biomass

Gasification is one of the thermochemical pathways of biomass conversion that produces synthesis gas, tar, and char. This study aims to convert algal residues via gasification at different operating conditions; temperature, equivalence ratio, and biomass loading. The study was carried out in 3 steps; (1) testing the outcomes of temperature and loading effects on synthesis gas yield, (2) experimental optimization of gasification via Design Expert, and (3) theoretical optimization of gasification via Aspen Plus simulation. Temperature and equivalence ratio highly influenced synthesis gas composition, while loading demonstrated less effect on the synthesis gas composition. The experimental and simulated gasification outcomes were compared to obtain optimized conditions that produce high H2 and CO yields. The data were validated using root mean square error. The optimized temperature, loading, and equivalence ratio were found for both algal residues that produced 36.38 and 13.28mol% of H2 and CO, respectively for lipid extracted algae (LEA) and 47.99 and 26.05mol% of H2 and CO, respectively for fucoidan extracted seaweeds (FEA). There was a considerable variation between experimental and simulated data due to the simulation and experimental limitations. The average Carbon Conversion Efficiency values were 66.36 and 80.42% for LEA and FES, respectively, denoting that LEA produced less carbon-containing products, while FES produced more carbon-containing products. In conclusion, LEA gasification yielded more H2 while FEA produced more CO.

Optimization of Algae Residues Gasification: Experimental and Theoretical Approaches

The amino acids from microalgae could be used as a substitute for food and feed supplements in the future. This study investigates the production of amino acids from microalgae Nannochloropsis sp. biomass using subcritical water technology approaches. The yield and composition of amino acids produced from subcritical water of microalgae Nannochloropsis sp. were evaluated at different temperatures (160-350 °C), time (3-30 min), and biomass loadings (1- 15% w/v). Overall results showed that the highest yield of total amino acids (1531.98 mg/100 g algae) was obtained at subcritical water operating conditions of 280 °C, 15 min reaction time, and 1% biomass loading. The studied operating conditions produced a higher yield of non-essential amino acids compared to essential amino acids. The study demonstrated that each of the individual amino acids investigated produced the highest at different ranges of subcritical water conditions. Thus, the obtained profile of the individual amino acid showed that careful management of operating parameters (temperature, time, and biomass loading) is crucial for identifying the amino acids of interest via subcritical water technology.

Profile of Amino Acids Production from Microalgae Nannochloropsis sp. Biomass using Subcritical Water Technology

Malaysia adopted the GHS through the CLASS Regulations of 2013. This new approach for chemical classification is inconsistent with the CIMAH Regulations of 1996 and has introduced new hazard categories, which are not included in the current major hazard identification criteria. For identifying MHI in Malaysia, the chemicals need to be reclassified. Therefore, this study aims to propose the indicative criteria for major hazard installation that are aligned with CLASS in order to simplify the process. The newly listed chemical threshold quantity, focusing on the acute toxicity group, was also identified. The steps involved include comparing major hazard legislation in the selected country, matching the criteria of CIMAH and CLASS, and reclassifying chemicals in Schedule Two of CIMAH. For estimation of TQ for nitric acid, dispersion modeling was selected. A guide for selecting suitable parameters was developed, ALOHA software was used to simulate the model, and the estimation result for nitric acid was 15.5 tonnes. This study provides the opportunity to improve CIMAH by applying CLASS hazard categories to identify major hazard installation. The guide to estimate TQ could be used for other acute toxicity chemicals as an option for regulators to negotiate and decide the TQ in CIMAH.

Redesign identification criteria for major hazard installation in Malaysia

The primary requirements for high-biomass-concentration microalgal cultivation include a photon source and distribution, efficient gas exchange and suitable growth medium composition. However, for mass outdoor production of microalgae, growth medium composition is a major controlling factor as most of the other factors such as light source and distribution are virtually uncontrollable. This work utilises an elemental balance approach between growth medium and biomass compositions to obtain high-density microalgal cultures in an open system. F medium, commonly used for the cultivation of marine microalgae such as Tetraselmis suecica was redesigned on the basis of increasing the biomass capacity of its major deficient components to support high biomass concentrations (τ ∼ 5.0 % for N, S and τ ∼ 10 % P), and the entire formulation was dissolved in 0.2 um sterile filtered natural seawater. Results show that the new medium (F') displayed a maximum biomass concentration and total lipid concentration of 1.29 g L 1 and 108.7 mg L 1 respectively, which represents over 2-fold increase compared to that of the F medium. Keeping all variables constant except growth medium, and using F medium as the base case of 1 medium cost (MC) unit mg -1 lipid, the F' medium yielded lipid at a cost of only 0.35 MC unit mg -1 lipids. These results show that greater amounts of biomass and lipids can be obtained more economically with minimal extra effort simply by using an optimised growth medium.

Razif Harun

Papers

Technoeconomic Assessment of Large‐Scale Production of Bioethanol from Microalgal Biomass

Optimization of Algae Residues Gasification: Experimental and Theoretical Approaches

Profile of Amino Acids Production from Microalgae Nannochloropsis sp. Biomass using Subcritical Water Technology

Redesign identification criteria for major hazard installation in Malaysia

Cultivation medium design via elemental balancing for tetraselmis suecica