Differential Evolution Algorithm Based Self-adaptive Control Strategy for Fed-batch Cultivation of Yeast

In the fed-batch cultivation of Saccharomyces cerevisiae, excessive glucose addition leads to increased ethanol accumulation, which will reduce the efficiency of glucose utilization and inhibit product synthesis. Insufficient glucose addition limits cell growth. To properly regulate glucose feed, a different evolution algorithm based on self-adaptive control strategy was proposed, consisting of three modules (PID, system identification and parameter optimization). Performance of the proposed and conventional PID controllers was validated and compared in simulated and experimental cultivations. In the simulation, cultivation with the self-adaptive control strategy had a more stable glucose feed rate and concentration, more stable ethanol concentration around the set-point (1.0 g•L^-1), and final biomass concentration of 34.5 g-DCW•L^-1, 29.2% higher than that with a conventional PID control strategy. In the experiment, the cultivation with the self-adaptive control strategy also had more stable glucose and ethanol concentrations, as well as a final biomass concentration that was 37.4% higher than that using the conventional strategy.     

A hybrid support vector machine and fuzzy reasoning based fault diagnosis and rescue system for stable glutamate fermentation

In industrial glutamate fermentation by biotin-auxotroph Corynebacterium glutamicum, biotin content variation in corn slurry greatly affects fermentation performance. To maintain the fermentation stability, a hybrid support vector machine (SVM) and fuzzy reasoning based fault diagnosis and rescue system was developed. The system uses SVM outputs as the inputs of the fuzzy reasoning classifier having a couple of production rules and condition membership functions related with SVM outputs, to categorize multiple faults. The effectiveness of the proposed system was verified in a normal fermentation run and two abnormal runs with different biotin initial-content faults with the aid of using on-line measurable data such as ammonia consumption rate and CO₂ evolution rate. The results indicated that the proposed faults-diagnosis system could cluster multiple fermentation faults quickly, accurately and stably, and faults and their types could be identified at the earliest fermentation stage. Based on the diagnosis results, the proposed system was further applied for real fault-rescue in two fermentations with different biotin initial-content faults. In both cases, by immediately taking relevant rescue measures after identifying the faults and their types, glutamate fermentations with initial faults were restored to normal, and final glutamate concentrations reached a normal level of 75–80 g/L at 34 h.     

Simulation and experimental verification of flexible roll forming of steel sheets

Roll forming is a sheet metal forming process that has been used for decades. Usually roll-formed sections have a constant cross section. Flexible roll forming is a brand new forming process that produces parts with variable cross sections, in which the rollers translate back and forth in a direction that is perpendicular to the sheet feeding direction. Theoretical analysis gives an explanation of the plane strain state, compressive stresses, tensile stresses, and shear stresses in flexible roll forming. In order to analyze the mechanics and the deformation characteristics of flexible roll forming, the finite element method (FEM) model of a 17-step flexible roll forming process is established. The yield criterion used in the FEM simulation is Hill 48, and the parameters of which are solved with the yield stresses under different loading conditions and are firstly verified with a plane strain tensile test. The complicated roller paths are realized with data extracted from the computer-aided design (CAD) files with VC++ programs developed by the authors. We developed the first flexible roll forming prototype machine in China, with which the roll forming experiment of a side door beam is performed. Final shapes of the experimental and numerical results are compared. It is shown that the numerical results based on Hill 48 yield criterion that is solved with yield stresses agree well with the experimental results, which indicates that the simulation model can well reflect the real forming process. Detailed analysis of the distribution and history of plastic strain, longitudinal strain, shear strain, and thickness of both the constant cross section and the variable cross section is performed, which is of great help to understand this forming process.     

Development of a locally sustainable functional food based on mutandabota,a traditional food in southern Africa

A probiotic dairy product was developed on the basis of a traditional dish called mutandabota to enable resource-poor populations in southern Africa to benefit from a functional food. Mutandabota is widely consumed in rural southern Africa, making it an ideal food matrix to carry probiotics. First, a process to produce probiotic mutandabota was designed. Raw cow milk was boiled and subsequently cooled to ambient temperature (25°C). Next, dry pulp from the fruit of the baobab tree (Adansonia digitata L.) was added to the milk at a concentration of 4% (wt/vol). This mixture was inoculated with the probiotic Lactobacillus rhamnosus yoba and left to ferment for 24 h, while the growth of the bacterial culture was monitored. Final ingredients were then added to produce probiotic mutandabota that had 14% (wt/vol) baobab fruit pulp and 7% (wt/vol) sugar in cow milk. The pH of probiotic mutandabota was pH 3.5, which ensures that the product is microbiologically safe. The viable plate count of L. rhamnosus yoba increased from 5.8 ± 0.3 log cfu/mL at the point of inoculation to 8.8 ± 0.4 log cfu/mL at the moment of consumption, thereby meeting the criterion to have a viable count of the probiotic bacterium in excess of 6 log cfu/mL of a product. Baobab fruit pulp at 4% promoted growth of L. rhamnosus yoba with a maximal specific growth rate (μ_max) of 0.6 ± 0.2/h at 30°C. The developed technology, though specific for this particular product, has potential to be applied for the delivery of probiotics through a variety of indigenous foods in different regions of the world. Upon consumption, probiotic mutandabota is expected to improve the population's intestinal health, which is especially relevant for vulnerable target groups such as children and elderly people.     

A methodology for design and reconfiguration of reconfigurable bending press machines (RBPMs)

Customer requirements have become very dynamic and unprecedented. A manufacturing paradigm called reconfigurable manufacturing system was initiated to adjust the physical machine entities. The main enabler of a machine structure’s reconfigurability is a modular design approach. The paper explains a function-driven object-oriented methodology for the design and reconfiguration of RBPMs. The complete method aims to optimise initial design of RBPMs, followed by subsequent design of RPBM modules which are stored in a module library so as to enable full-automatic reconfiguration of the RBPMs. The methodology is implemented on a pilot project to design a 145 ton bending capacity RBPM, with a maximum reconfigured length of 5?m and total height of 3?m. In order to deduce the design for the reconfigurable bending press machine, the reconfigurability needs were identified first, followed by the construction of a function tree for the machine. The function tree identifies the primary function for the RBPM, which is to bend sheet metal. The primary function is further decomposed to lower level functions until terminal functions are arrived at. The terminal functions are then used to identify the modules for the machine. The modules implement specific brunches of the machine functions.     

初始生物素含量波动时谷氨酸发酵关键酶系的酶活变化模式

谷氨酸发酵培养基中的生物素初始含量会随玉米浆来源、批次的不同出现波动,进而影响谷氨酸发酵性能和稳定性。本文研究分析了谷氨酸发酵中,初始生物素含量正常/不当,特别是初始含量不当、采取补救措施条件下的丙酮酸、异柠檬酸和α-酮戊二酸代谢节点处关键酶的活性变化。生物素匮乏时,催化主代谢途径的关键酶活性均被弱化,特别是α-酮戊二酸脱氢酶完全失活,能量代谢主要靠乙醛酸循环维持。当发现生物素匮乏并补加生物素后,中心代谢途径关键酶--丙酮酸脱氢酶的活性恢复到正常水平,TCA重新成为主要供能途径。生物素过量时,丙酮酸羧化酶和谷氨酸脱氢酶活性基本不变,而其他关键酶均被激活。当发现生物素过量并添加吐温40后,丙酮酸脱氢酶和异柠檬酸脱氢酶依旧保持很高活性,而α-酮戊二酸脱氢酶和异柠檬酸裂解酶的活性则下降到正常水平。采用上述补救措施可以挽救因初始生物素匮乏或过量所引起的错误发酵,终酸浓度均可恢复到对照（生物素亚适量）水平（75～80 g·L^-1）。另外,对生物素初始含量和吐温添加进行复合式调控,终酸浓度可进一步提高,达到87 g·L^-1,比对照提高8.8%。     

Febrile episodes in children with cancer in the United Arab Emirates

We report the first patient with a partial trisomy and a partial monosomy of the long arm of chromosome 4: 46,XY, inv dup(4)(pter-->q32::q32-->q26), del(4)(q32-->qter). The boy died from a complex cardiac defect (monoventricle, monoatrium and truncus arteriosus) in combination with a diaphragmatic hernia. In addition he had preaxial polydactyly of the right hand. We compare the clinical features with data from the literature. The phenotype of the patient mainly resembles that in patients with a terminal deletion 4q32.     

Hybrid thermal model for swimming pools based on artificial neural networks for southeast region of Brazil

Nowadays, the usage of systems based on solar energy have been largely stimulated. The correct designing and efficiency of these systems are highly dependent of the seasonal climatic characteristics of the regions where they will be installed. In this work, we propose a hybrid structure to simulate the thermodynamic behavior of pools, which uses neural computational models to incorporate the climatic information of the regions being analyzed. The neural models have as input variables data of geographic position such as: elevation, latitude and longitude, what permits to delineate the climatic profile of the region being considered. The human activity is another factor that directly influences the thermodynamic behavior of pools and, therefore, is also considered. In this work, changes of volume are estimated in order to track losses due to the human activity.     

Biophotonics for improving algal photobioreactor performance: A review

The use of algae as a feedstock for biofuels production has drawn considerable attention due to their high biomass yield, their ability to be cultivated using degraded water on nonarable land, and their ability to recover nutrients from wastewater. Although algae have the potential to provide biomass for biofuels, some challenges remain and the limitations may be overcome by improving algal growth rates together with lipid synthesis. To achieve this, scientific researchers have focused on isolating and screening algal strains with better growth rates and lipid synthesis capabilities, bioengineering, and optimizing culture systems. The present review focuses on the biophotonic-based manipulations that can be applied to optimize solar-powered photobioreactors (PBRs). Hence, three different types of solar filters are reviewed herein, that is, the colored glass, thin-film, and thermochromic filters. This review provides evidence that bright red-colored glass filters can lower the spectral intensity of solar radiation from 1982.13 to 393.71 μmol m⁻² s⁻¹, which is preferable for improved biomass productivity. Changing filter color, once the desired biomass concentration has been amassed, to medium blue or bright pink further improves lipid yield. A 34% improvement in biomass productivity was observed for Chlorella vulgaris cultured under thin-film filters. Thin-film filters are also effective in regulating PBR temperature within the 24–31°C range, which is tolerable for most algal species. Furthermore, this study highlights that the applicability of thermochromic filters in PBR designs is still yet to be investigated. Thermochromic filters are reflective and absorptive under high and low temperatures, respectively, a technology that can be a solution to the overheating challenge of PBRs. This review recommends the coupling of these light filtration technologies to the horizontal tubular PBR for effective utilization of solar radiation in algaculture.     

Scale-up of L-lactic acid production by mutant strain Rhizopus sp. MK-96-1196 from 0.003 m3 to 5 m3 in airlift bioreactors

In order to study the feasibility of commercial-scale L-lactic acid production by Rhizopus sp. MK-96-1196 using large scale airlift bioreactors (ALBs), a scale-up study from 0.003 m3 to 5 m3 ALB was carried out using oxygen transfer rate (OTR) as the scale-up criterion. Enhanced L-lactic acid production was achieved at OTRs higher than 0.28 (g-O2/l/h) irrespective of the scale of the bioreactor in question: in the range of 0.003 m3 to 5 m3, more than 90 g/lL-lactic acid was produced with a yield of approximately 80%, based on the initial glucose concentration. In future research, we plan to design an ALB greater than 3000 m3 (working volume: 2000 m3) for further studies on the production of L-lactic acid in large quantities.