Lipid Production by Culturing Oleaginous Yeast and Algae with Food Waste and Municipal Wastewater in an Integrated Process

Food waste and municipal wastewater are promising feedstocks for microbial lipid biofuel production, and corresponding production process is to be developed. In this study, different oleaginous yeast strains were tested to grow in hydrolyzed food waste, and growths of Cryptococcus curvatus, Yarrowia lipolytica, and Rhodotorula glutinis in this condition were at same level as in glucose culture as control. These strains were further tested to grow in municipal primary wastewater. C. curvatus and R. glutinis had higher production than Y. lipolytica in media made from primary wastewater, both with and without glucose supplemented. Finally, a process was tested to grow C. curvatus and R. glutinis in media made from food waste and municipal wastewater, and the effluents from these processes were further treated with yeast culture and phototrophic algae culture; 1.1 g/L C. curvatus and 1.5 g/L R. glutinis biomass were further produced in second-step yeast cultures, as well as 1.53 and 0.58 g/L Chlorella sorokiniana biomass in phototrophic cultures. The residual nitrogen concentrations in final effluents were 33 mg/L and 34 mg/L, respectively, and the residual phosphorus concentrations were 1.5 and 0.6 mg/L, respectively. The lipid contents in the produced biomass were from 18.7% to 28.6%.     

M x /G/1 Queue with Multiple Vacations

Abstract

In this article, we study a queueing system M ^x /G/1 with multiple vacations. The probability generating function (P.G.F.) of stationary queue length and its expectation expression are deduced by using an embedded Markov chain of the queueing process. The P.G.F. of stationary system busy period and the probability of system in service state and vacation state also are obtained by the same method. At last we deduce the LST and mean of stationary waiting time in the service order FCFS and LCFS, respectively.     

Promoting CO2 Electroreduction to Multi-Carbon Products by Hydrophobicity-Induced Electro-Kinetic Retardation

Advancing the performance of the Cu-catalyzed electrochemical CO₂ reduction reaction (CO₂RR) is crucial for its practical applications. Still, the wettable pristine Cu surface often suffers from low exposure to CO₂, reducing the Faradaic efficiencies (FEs) and current densities for multi-carbon (C₂₊) products. Recent studies have proposed that increasing surface availability for CO₂ by cation-exchange ionomers can enhance the C₂₊ product formation rates. However, due to the rapid formation and consumption of *CO, such promotion in reaction kinetics can shorten the residence of *CO whose adsorption determines C₂₊ selectivity, and thus the resulting C₂₊ FEs remain low. Herein, we discover that the electro-kinetic retardation caused by the strong hydrophobicity of quaternary ammonium group-functionalized polynorbornene ionomers can greatly prolong the *CO residence on Cu. This unconventional electro-kinetic effect is demonstrated by the increased Tafel slopes and the decreased sensitivity of *CO coverage change to potentials. As a result, the strongly hydrophobic Cu electrodes exhibit C₂₊ Faradaic efficiencies of ≈90 % at a partial current density of 223 mA cm⁻², more than twice of bare or hydrophilic Cu surfaces.     

供应链中的MQ(t)/Gj/∞排队群

本文研究由一个非时齐Poisson到达过程驱动的多个MQ(t)／Gj／∞型排队系统．当一个K型到达发生时(K(?){1,…,m}),对每一个j∈K,顾客按批量QjK进入排队系统j,(Q1K,…,QmK)是相依的随机向量．我们导出了联合队长过程和联合输出过程的多变量母函数,并给出各排队系统之间的相关性分析．这些结果为非时齐供应链分析提供了理论依据     

Selection of Microalgae and Cyanobacteria Strains for Bicarbonate-Based Integrated Carbon Capture and Algae Production System

Using microalgae to capture CO₂ from flue gas is an ideal way to reduce CO₂ emission, but this is challenged by the high cost of carbon capture and transportation. To address this problem, a bicarbonate-based integrated carbon capture and algae production system (BICCAPS) has been proposed, in which bicarbonate is used for algae culture, and the regenerated carbonate from this process can be used to capture more CO₂. High-concentration bicarbonate is obligate for the BICCAPS. Thus, different strains of microalgae and cyanobacteria were tested in this study for their capability to grow in high-concentration NaHCO₃. The highest NaHCO₃ concentrations they are tolerant to were determined as 0.30 M for Synechocystis sp. PCC6803, 0.60 M for Cyanothece sp., 0.10 M for Chlorella sorokiniana, 0.60 M for Dunaliella salina, and 0.30 M for Dunaliella viridis and Dunaliella primolecta. In further study, biomass production from culture of D. primolecta in an Erlenmeyer flask with either 0.30 M NaHCO₃ or 2 % CO₂ bubbling was compared, and no significant difference was detected. This indicates BICCAPS can reach the same biomass productivity as regular CO₂ bubbling culture, and it is promising for future application.     

Production of ω-3 polyunsaturated fatty acids from cull potato using an algae culture process

Algal cultivation for converting cull potato to docosahexaenoic acid (DHA) was studied. Schizochytrium limacinum SR21 was selected as the better producing strain, compared with Thraustochytrium aureum because of higher cell density and DHA content. Used as both carbon and nitrogen source, an optimal ratio of hydrolyzed potato broth in the culture medium was determined as 50%, with which the highest production of 21.7 g/L dry algae biomass and 5.35 g/L DHA was obtained, with extra glucose supplemented. Repeat culture further improved the cell density but not fed batch culture, suggesting limited growth was most likely caused by metabolites inhibition.     

The discrete time Geom/Geom/1 queue with multiple working vacations

In this paper, we study a discrete time Geom/Geom/1 queue with multiple working vacations. Using the quasi birth and death chain and matrix-geometric solution method, we give distributions for the number of customers in system and the waiting time of a customer and their stochastic decomposition structures, and obtain distributions of the additional number of customers and additional delay. Furthermore, we derive the formulae of expected regular busy period and expected busy cycle. Finally, by numerical examples, we analyze the effect of the parameters on the expected queue length and sojourn time.     

Model Checking Fuzzy Computation Tree Logic Based on Fuzzy Decision Processes with Cost

In order to solve the problems in fuzzy computation tree logic model checking with cost operator, we propose a fuzzy decision process computation tree logic model checking method with cost. Firstly, we introduce a fuzzy decision process model with cost, which can not only describe the uncertain choice and transition possibility of systems, but also quantitatively describe the cost of the systems. Secondly, under the model of the fuzzy decision process with cost, we give the syntax and semantics of the fuzzy computation tree logic with cost operators. Thirdly, we study the problem of computation tree logic model checking for fuzzy decision process with cost, and give its matrix calculation method and algorithm. We use the example of medical expert systems to illustrate the method and model checking algorithm.     

空竭服务Geom/G/1休假模型

本文用嵌入Markov链的方法证明了Geom／G／1的边界状态变体模型的随机分解定理，同时又证明两种具体模型的结果．     

Carbohydrate Analysis in Fermentation Samples by Reversed-Phase Liquid Chromatography with Mass Spectrometry Detection Using Precolumn Derivatization with Dibenzylamine

Chromatographia - Liquid chromatography–mass spectrometry (LC–MS) technique has been widely used for the determination of trace carbohydrate compounds in biological samples. However,...