Pellet Growth Research Articles

Online Monitoring of Iron Ore Pellet Size Distribution Using Lightweight Convolutional Neural Network

An improved U-Net based convolutional neural network (CNN) is proposed in this paper for online size monitoring of iron ore pellets. The proposed CNN model is a lightweight version of U-Net. In the proposed model each convolution block of the encoder subnet consists of a concatenated <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 1$</tex-math> </inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times 3$</tex-math> </inline-formula> filter kernel, a batch normalization layer, and a ReLU nonlinearity. The proposed CNN model efficiently detects the pellets even under variable illumination conditions and images with overlapping pellets. The proposed model is evaluated using images of iron ore pellets acquired at the discharge end of a pelletizer disc. The proposed CNN model performs satisfactorily using <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim$</tex-math> </inline-formula> 39% less learnable parameters, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim$</tex-math> </inline-formula> 16% reduced computational cost than the original U-Net model. The proposed model outperforms the conventional U-Net, different variants of U-Nets, FCN, and SegNet in weighted IoU, BF Score, global accuracy, SSIM, and PSNR. Experimental validation also shows a good agreement between the obtained pellet size distribution and the manual sieving result. This makes the proposed algorithm suitable for online pellet size-distribution measuring instruments. This method provides a more accurate and fast size monitoring system for iron ore pellets, ideal for real-time industrial applications. The image dataset and source codes are available at the below given link. https://github.com/aryadeo/Pellet_Size_Distribution. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —Due to the advent of digitalization in industries, several attempts are being made to use innovative industrial monitoring systems in steel manufacturing plants. Most of the pellet plants in steel industries use human supervision for pellet growth monitoring. In this paper, a camera-based pellet size distribution monitoring method is proposed. A novel deep learning-based algorithm is used for the detection of pellets from the captured image followed by computation of pellet size analysis. Due to low computational complexity and better accuracy, the proposed method is suitable for online pellet size distribution system development compared to other previously proposed methods. However, protection from the harsh industrial environment is required for the uninterrupted and continuous operation of the system. As a future scope, the obtained pellet size information can be used as one of the control variables in designing a control system for the automated operation of the pelletizer disc.

BMP9 is a potent inducer of chondrogenesis, volumetric expansion and collagen type II accumulation in bovine auricular cartilage chondroprogenitors.

Reconstruction of the outer ear currently requires harvesting of cartilage from the posterior of the auricle or ribs leading to pain and donor site morbidity. An alternative source for auricular reconstruction is in vitro tissue engineered cartilage using stem/progenitor cells. Several candidate cell-types have been studied with tissue-specific auricular cartilage progenitor cells (AuCPC) of particular interest. Whilst chondrogenic differentiation of competent stem cells using growth factor TGFβ1 produces cartilage this tissue is frequently fibrocartilaginous and lacks the morphological features of hyaline cartilage. Recent work has shown that growth factor BMP9 is a potent chondrogenic and morphogenetic factor for articular cartilage progenitor cells, and we hypothesised that this property extends to cartilage-derived progenitors from other tissues. In this study we show monoclonal populations of AuCPCs from immature and mature bovine cartilage cultured with BMP9 produced cartilage pellets have 3-5-fold greater surface area in sections than those grown with TGFβ1. Increased volumetric growth using BMP9 was due to greater sGAG deposition in immature pellets and significantly greater collagen accumulation in both immature and mature progenitor pellets. Polarised light microscopy and immunohistochemical analyses revealed that the organisation of collagen fibrils within pellets is an important factor in the growth of pellets. Additionally, chondrocytes in BMP9 stimulated cell pellets had larger lacunae and were more evenly dispersed throughout the extracellular matrix. Interestingly, BMP9 tended to normalise the response of immature AuCPC monoclonal cell lines to differentiation cues whereas cells exhibited more variation under TGFβ1. In conclusion, BMP9 appears to be a potent inducer of chondrogenesis and volumetric growth for AuCPCs a property that can be exploited for tissue engineering strategies for reconstructive surgery though with the caveat of negligible elastin production following 21-day treatment with either growth factor.

Enhancing Monascus Pellet Formation for Improved Secondary Metabolite Production.

Filamentous fungi are well-known for their ability to form mycelial pellets during submerged cultures, a characteristic that has been extensively studied and applied. However, Monascus, a filamentous saprophytic fungus with a rich history of medicinal and culinary applications, has not been widely documented for pellet formation. This study aimed to investigate the factors influencing pellet formation in Monascus and their impact on citrinin production, a key secondary metabolite. Through systematic exploration, we identified pH and inoculum size as critical factors governing pellet formation. Monascus exhibited optimal pellet growth within the acidic pH range from 5 to 6, resulting in smaller, more homogeneous pellets with lower citrinin content. Additionally, we found that inoculum size played a vital role, with lower spore concentrations favoring the formation of small, uniformly distributed pellets. The choice of carbon and nitrogen sources also influenced pellet stability, with glucose, peptone, and fishmeal supporting stable pellet formation. Notably, citrinin content was closely linked to pellet diameter, with larger pellets exhibiting higher citrinin levels. Our findings shed light on optimizing Monascus pellet formation for enhanced citrinin production and provide valuable insights into the cultivation of this fungus for various industrial applications. Further research is warranted to elucidate the molecular mechanisms underlying these observations.

PSII-30 Effect of Dietary Alpha-Amylase Enzyme Supplementation on Growth Performance and Carcass Quality of Crossbred Dairy Beef Bulls Fed Pellet Or Mash High-Concentrate Diets

Abstract The aim of this study was to evaluate the effect of dietary alpha-amylase supplementation on growth performance and carcass quality in crossbred dairy beef bulls fed either pellet or mash high-concentrate diets. Two parallel studies were conducted in two barns. In the first barn, 138 bulls (170 ± 2.3 kg of BW, and 148 ± 0.7 days of age) were grouped in 8 pens of 16 to 19 animals/pen and fed pelleted concentrate (PELLET study); and in the second barn, 148 (180 ± 1.6 kg of BW, and 150 ± 0.7 days of age) were grouped in 8 pens of 17 to 19 animals/pen and fed mash concentrate (MASH study). All bulls were fed concentrate (Table 1), straw, and water ad libitum. In each study, pens were assigned to one of 2 treatments: 1) CTR, no amylase supplementation; 2) RUM, RumiStar600 CT concentrate inclusion [630 mg/kg DM, based on 600 kilo novo units (KNU) of alpha-amylase activity]. After 196 days, divided in seven 28-days periods, where daily concentrate intake per pen, and BW per animal every 28 days was recorded animals were transported to slaughterhouse at different days within a month. Also, on days 0, 42, 84 and 168 concentrate samples were collected for enzyme activity and nutrient content analyses. Carcass quality was recorded at the slaughterhouse, bulls of PELLET study were slaughtered on average at 236 days of study and bulls of MASH study were slaughtered on average at 226 days of study. Data of each study were analyzed using a mixed model. In PELLET study, growth performance and carcass quality were not affected by treatments; however, conformation grade (SEUROP) was improved (P = 0.03) in RUM bulls compared with CTR bulls (score R: 18 vs. 5 %; score O: 54 vs. 56 %; score P: 28 vs. 39 %; RUM vs. CTR, respectively). Moreover, feed conversion ratio (FCR) was numerically (P = 0.11) improved in RUM fed bulls compared with CTR fed bulls (4.65 vs. 4.99 kg DM/kg, RUM vs. CTR, respectively;). In the MASH study, only an interaction between treatment by time in BW (P = 0.04) was observed; RUM bulls tended to be heavier than CTR bulls in the period 7 (476 vs. 470 ± 3.2 kg, RUM vs. CTR, respectively; P = 0.10). In conclusion, in crossbred dairy beef bulls fed high-concentrate diets with alpha-amylase supplementation (600 KNU of alpha-amylase activity/kg DM of concentrate) for at least 196 days improved FCR and carcass conformation grade when concentrate presentation form was pellet.

The strategy for developing wood pellets as sustainable renewable energy in Indonesia

Concerns about carbon emissions from the use of fossil fuels are felt globally. In order to support sustainable energy in the future, efforts to reduce emissions are carried out by developing wood pellets as renewable energy. The Indonesian government is also concerned about advancing renewable energy technology to supply the country's industries and residents with electricity. Several factors and substitute sources hamper the growth of wood pellets as a renewable energy source in Indonesia. Studies from the past point to four obstacles to low-carbon development: sociocultural, economic, technological, and governmental. Therefore, this article aims to determine the inhibiting factors and seek the best decisions for developing wood pellets as a renewable energy source. Interpretive Structural Modeling (ISM) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) procedures were applied to determine the best strategy for developing wood pellets in Indonesia. This study recruited several vital informants to identify factors and assess each alternative. The results of the analysis using ISM provide information that the Raw Materials (D11) and Standard Products (D6) sub-factors are vital in developing wood pellets as one of the renewable energies in Indonesia. Furthermore, the analysis of selecting the best alternative using TOPSIS shows that Alternative A1 (Government Incentives), with a weight of 0.825, has the longest distance. A more thorough evaluation of the articles is still needed to produce more accurate findings.

Comprehensively dissecting the hub regulation of PkaC on high-productivity and pellet macromorphology in citric acid producing Aspergillus niger.

Summary Aspergillus niger, an important industrial workhorse for citric acid production, is characterized by polar hyphal growth with complex pelleted, clumped or dispersed macromorphologies in submerged culture. Although organic acid titres are dramatically impacted by these growth types, studies that assess productivity and macromorphological changes are limited. Herein, we functionally analysed the role of the protein kinase A (PKA)/cyclic adenosine monophosphate (cAMP) signalling cascade during fermentation by disrupting and conditionally expressing the pkaC gene. pkaC played multiple roles during hyphal, colony and conidiophore growth. By overexpressing pkaC, we could concomitantly modify hyphal growth at the pellet surface and improve citric acid titres up to 1.87‐fold. By quantitatively analysing hundreds of pellets during pilot fermentation experiments, we provide the first comprehensive correlation between A. niger pellet surface morphology and citric acid production. Finally, by intracellular metabolomics analysis and weighted gene coexpression network analysis (WGCNA) following titration of pkaC expression, we unveil the metabolomic and transcriptomic basis underpin hyperproductivity and pellet growth. Taken together, this study confirms pkaC as hub regulator linking submerged macromorphology and citric acid production and provides high‐priority genetic leads for future strain engineering programmes.

Investigation on Loss on Ignition to Study the Effect of Iron Ore Mineralogy in Green Pellet Growth Kinetics

Investigation on Loss on Ignition to Study the Effect of Iron Ore Mineralogy in Green Pellet Growth Kinetics

Preparation and Characterization of Large Grain UO2 for Accident Tolerant Fuel

Large grain UO2 is considered as an accident tolerant fuel with great application potential due to its competitive advantage of good fission gas retention. In this paper, the influence of preparation parameters such as sintering atmosphere, mixing process, powder pretreatment and grain growth additives on the grain size of UO2 is systematically studied. The result shows that the factors mentioned above have different effects on the grain size of UO2. The grain growth of UO2 pellet sintered in oxidizing atmosphere is better than those in reducing atmosphere. The wet mixing process has a significant advantage over the dry mixing process. In addition, the powder pretreatment has little effect on grain growth while the influence of additives plays the main role. Large grain UO2 pellets with uniform grain size up to 150 μm are successfully prepared. Finally, the thermo-physical properties of the pellets are investigated.

Synthesis of simulated fuels containing CsI under gas-tight condition

Abstract A synthesis method of simulated fuel (SIMFUEL) containing highly volatile compound of cesium iodide (CsI) was established based on a gas-tight sintering technique. This method can enhance the grain growth of the SIMFUEL pellets by increasing sintering temperature and time. The CsI content in the SIMFUEL did not significantly decrease even for 10 h sintering time and its final value can be quantitatively controlled by adjusting its vaporization amount. A slower heating rate after the melting of CsI can promote the dispersion of liquid CsI on the grain boundaries and give a very small CsI particle size (mostly below 0.1 μm).

Aspectos técnicos da produção de &lt;i&gt;pellets&lt;/i&gt; de madeira

A evolução da política energética dos países desenvolvidos, associada à procura por fontes renováveis como a biomassa florestal, impulsionou, desde o início dos anos 2000, o crescimento da produção de pellets de madeira no mundo. O mercado de pellets tornou-se exigente em qualidade e deve lidar com a concorrência de outras fontes de energia, requerendo dos produtores um controle rigoroso de custo bem como um bom domínio técnico da produção. Dessa forma, realizou-se uma revisão bibliográfica sobre os aspectos técnicos da produção de pellets e as possibilidades e as exigências do mercado para que o Brasil possa aproveitar as oportunidades e valorizar o seu potencial florestal.

Bioflocculation of cyanobacteria with pellets of Aspergillus niger: Effects of carbon supplementation, pellet diameter, and other factors in biomass densification

One of the hurdles of renewable energy production from photosynthetic microorganisms is separating the biomass from water in cultures. Bioflocculation with filamentous fungus Aspergillus niger, an alternative low-cost method used for such separation, was studied with four cyanobacteria. Cocultures with Spirulina maxima and Synechococcus subsalsus resulted in bioflocculation efficiencies up to 94%, while with Anabaena variabilis and Anabaena siamensis bioflocculation did not occur. S. subsalsus was selected to evaluate the effect of cyanobacterial initial concentration, fungal:cyanobacterial ratio, carbon supplementation, and pH on biomass densification. Bioflocculation efficiencies up to 98% in 48 h were obtained with fungal:cyanobacterial ratio 1:5 and carbon supplementation. Despite the lower efficiency (54%), the highest concentration factor of S. subsalsus suspension (62.8 – from 0.9 to 56.5 g/L) was obtained with ratio 1:5 without supplementation. This result was attributed to the smaller pellet diameter (2.5 mm) and indicated that lower pellet growth is better for biomass densification.

Production of lignin-modifying enzymes by Trametes ochracea on high-molecular weight fraction of olive mill wastewater, a byproduct of olive oil biorefinery

The high-molecular weight fraction of olive mill wastewater (HMW-OMW), a byproduct of olive oil biorefinery, was used at the reactor level as the basal medium for production of laccase and Mn-dependent peroxidase (MnP) by Trametes ochracea. Three reactor systems, namely stirred tank reactors equipped with either Rushton turbines or marine impeller and draft tube (STR and STR-MD, respectively) and an air-lift reactor (ALR) were compared for this purpose. Although inocula were supplied as intact pellets, in both STR-based systems fungal growth evolved rapidly into a dispersed form while the ALR enabled the maintenance of the pellet growth mode. STR was deemed to be the most promising system since it best supported the production MnP activity on the HMW-OMW-based medium and its performance in laccase production did not differ from that observed with the STR-MD. Among the stirring regimes considered (250, 400, 500 and 600 rpm), the best production in the STR was observed at 500 rpm and 1.0 vvm for both laccase (8850 ± 270 IU L−1 on day 15) and MnP (17,027.4 ± 87.2 IU L-1 on day 13). When the inocula were supplied to the STR in homogenized form, the MnP production peak (16,856 ± 1070 IU L-1) was attained 8 days earlier than the previous condition and that of laccase was nearly doubled (14,967 ± 907 IU L-1). When compared with literature data, T. ochracea MnP production and productivity on the HMW-OMW-based medium were the highest reported for a wild-type fungal strain.

In vivo and in vitro efficient textile wastewater remediation by Aspergillus niger biosorbent.

In this work, the treatment of textile wastewater by a facile and high-efficiency technology using eco-friendly Aspergillus niger as a biosorbent was investigated. We measured physical changes (weight, size) during the formation and growth of fungus pellets and the pH values that influence the adsorption performance and biosorption mechanism. Three acid anionic dyes containing Acid Orange 56, Acid Blue 40 and Methyl Blue were chosen as model dyes to investigate batch adsorption efficiency. Two adsorption models (in vivo and in vitro) were adopted to decolorize the acid dyes. The results show that fungus pellets have excellent decoloration abilities with a high adsorption efficiency of 98% for 200 mg L−1 of acid dye. The pH value of the dye solution varied with the adsorption time and the dye removal efficiency greatly depended on the pH. The bioadsorption mechanism of nano-scale hyphae was revealed to be mainly due to electrostatic interactions caused by the pH change. Furthermore, the surface morphologies of the fungus after adsorption indicated that the dyes had been adsorbed on the surface of the fungus mycelia. Moreover, prepared 3D fungus/GO aerogels demonstrated superior dye removal abilities compared with fungus aerogels.

Lignocellulose integration to 1G-ethanol process using filamentous fungi: fermentation prospects of edible strain of Neurospora intermedia

BackgroundIntegration of first- and second-generation ethanol processes is one among the alternate approaches that efficiently address the current socio-economic issues of the bioethanol sector. Edible filamentous fungus capable of utilizing pentoses from lignocelluloses and also possessing biomass application as potential animal feed component was used as the fermentation strain for the integration model. This study presents various fermentation aspects of using edible filamentous fungi in the integrated first and second generation ethanol process model.ResultsFermentation of edible strain of N. intermedia on the integrated first and second-generation ethanol substrate (the mixture of dilute acid pretreated and enzymatically hydrolyzed wheat straw and thin stillage from the first-generation ethanol process), showed an ethanol yield maximum of 0.23 ± 0.05 g/g dry substrate. The growth of fungal pellets in presence of fermentation inhibitors (such as acetic acid, HMF and furfural) resulted in about 11 to 45% increase in ethanol production as compared to filamentous forms, at similar growth conditions in the liquid straw hydrolysate. Fungal cultivations in the airlift reactor showed strong correlation with media viscosity, reaching a maximum of 209.8 ± 3.7 cP and resulting in 18.2 ± 1.3 g/L biomass during the growth phase of fungal pellets.ConclusionN. intermedia fermentation showed high sensitivity to the dilute acid lignocellulose pretreatment process, with improved fermentation performance at milder acidic concentrations. The rheological examinations showed media viscosity to be the most critical factor influencing the oxygen transfer rate during the N. intermedia fermentation process. Mycelial pellet morphology showed better fermentation efficiency and high tolerance towards fermentation inhibitors.

Application and mechanism of nucleation-induced pelleting coagulation (NPC) in treatment of fracturing wastewater with high concentration of dissolved organic matter

To improve the separation efficiency of fluffy flocs during coagulation of fracturing wastewater with high concentration of dissolved organic matter, a novel nucleation-induced pelleting coagulation (NPC) process is proposed based on pelleting coagulation in this study. In the NPC process, nucleation agents were added to act as pellet seeds to generate high-density pellet flocs. The results implied that the necessary condition for the NPC process was to control the metastable state, i.e. zeta potential around −10 mV after addition of the coagulant, polyaluminium chloride (PAC). Diatomite, which was added after rapid mixing, was used as the nucleation agent, and its optimal dosage was about 100 mg/L with particle size 100–200 μm. In addition, the dosage of the coagulant aid, polyacrylamide (PAM), significantly affected the performance of the NPC process, and the optimal PAM dosage was 10 mg/L in this study. It was found that 60 rpm (G = 55.1 s−1) was the optimal hydraulic condition for pellet growth during slow mixing. The pellet floc settling velocity reached 14.9 mm/s and the particle size (d50) reached 4.6 mm with an effective density of 0.021 g/cm3 at the optimal condition, which was one order higher than that of conventional aluminium flocs.

Three dimensional typological studies using scanning electron microscopy for characterization of Termitomyces pellets obtained from submerged growth conditions

There are gaps in existing understanding of fungal pellet growth dynamics. We used scanning electron microscopy (SEM) for morphological characterization of the biomass organization of Termitomyces pellets for seven species: T. microcarpus (TMI1), T. albuminosus (TAL1, TAL2), T. striatus (TSTR), T. aurantiacus (TAUR), T. heimii (THE1, THE2), T. globulus (TGLO) and T. clypeatus (TCL1, TCL2, TCL3, TCL4, TCL5). We assessed the utility of SEM for morphological and structural characterization of Termitomyces spp. in three dimensional (3D) pellet form to identify ideal pellet morphology for industrial use. Typological classification of Termitomyces species was based on furrows, isotropy, total motifs and fractal dimensions. The pellets formed were entangled and exhibited highly compacted mycelial mass with microheterogeneity and microporosity. The mean density of furrows of Termitomyces species was between 10,000 and 11,300 cm/cm2, percentage isotropy was 30−80 and total motifs varied from 300 to 2500. TGLO exhibited the highest furrow mean density, 11243 cm/cm2, which indicated a compact, cerebroid structure with complex ridges and furrows, whereas TAL2 exhibited the lowest furrow density. TMI1a exhibited a high percentage isotropic value, 74.6, TSTR exhibited the lowest, 30.9. Total motif number also was used as a typological classification parameter. Fractal values were 2.64−2.78 for various submerged conditions of Termitomyces species. TAL1 exhibited the highest fractal dimension and TAL2 the lowest, which indicates the complexity of branching patterns. Three-dimensional SEM image analysis can provide insight into pellet micromorphology and is a powerful tool for exploring topographical details of pellets.

Characterization of reactive CaCO3 crystallization in a fluidized bed reactor as a central process of direct air capture

A laboratory-scale, fluidized-bed pellet reactor (BPR) was used to investigate a CaCO3 crystallization process for the recovery of CO2 in a Direct Air Capture (DAC) process. The BPR performance was validated against data from a pilot-scale unit. Subsequently, the pellet growth under process-relevant conditions was studied over a period of 144h.The experimental results with the BPR, containing a bed of pellets sized between 0.65 and 0.84mm, have shown that a calcium retention of 80% can be achieved at a fluidization velocity of 60mh−1 and a calcium loading rate of 3molh −1. This result is consistent with calcium retention observed at pilot scale operation and hence, results from the BPR are considered representative for the pilot scale unit.Starting with a bed of pellets sized between 0.15 and 0.5mm, the average pellet growth rate, G, at the reactor bottom increased from 8.1E-10 to 11E–10ms−1 at the onset and decreased to 4.9E–10m s−1 over the course of a 144h test. The calcium retention over the course the test showed the same trend (initial increase and final decrease) as the pellet growth rate.A theoretical bed growth model was developed and validated against data from the pilot scale and benchtop pellet reactors. The model was used to calculate the bed porosity and total pellet surface area in each control volume. The pellet surface area growth at the bottom of the reactor reproduced the pellet growth and retention data trends.

Empirical and experimental determination of the kinetics of pellet growth in filamentous fungi: A case study using Neurospora intermedia

Pellet morphology formation by filamentous fungi has gained a lot of attention because of its multiple benefits such as the ease of separation and smaller bioreactor volume requirement. Most reported kinetics studies on fungal pellet growth are centred on aeration, despite the experimental results pointing to the importance of other factors such as pH, substrates and product concentration etc., influencing the pellet formation. Hence a kinetic study on the effect of multiple factors such as aeration, substrate and product concentration and pH was done in this paper using Neurospora intermedia as a model organism, whose ability to form mycelial pellets was recently reported. The maximum growth rate of the pellets under uninhibited conditions at its optimal growth pH was 0.318h−1. The pellets were found to be inhibited by high product (ethanol) concentration with no growth occurring at 70gL−1 and above. High substrate concentration favoured the formation of loose fur-like fluffy pellets. The specific oxygen uptake rate of the pellets was between 0.27–0.9 mmol-O2 g-biomass−1h−1 depending on the pellet average diameter. The results from this kinetic study can be used for bioreactor design, operations and optimization of fermentation processes utilizing N. intermedia.

Effects of low-dose of TGF-β1 on maintaining bovine corneal stromal cell growth and retarding extra cellular matrix fibrosis in a three-dimensional culture model

Background Transforming growth factor-β1 (TGF-β1) plays an important role in corneal wound healing.The effects of TGF-β1 on the synthesis of extra cellular matrix (ECM) vary upon different concentrations.Previous studies focused on the effects of high concentration of TGF-β1 on keratocytes under the two-dimensional culture condition, and the effect of low concentration of TGF-β1 on the synthesis of ECM in keratocytes remains unclear. Objective This study was to investigate the growth of Pellet, a three-dimensional model of corneal stroma cells in vitro, and its ECM synthesis under a low concentration of TGF-β1. Methods Bovine corneal stromal cells were isolated from fresh bovine eyeballs by two-step digestion by collagenase and cultured using DMEM/F12 medium with 10% fetal bovine serum (FBS). Pellets derived fresh bovine keratocytes with culture medium containing 0.25 ng/ml TGF-β1+ 5% FBS and 0.50 ng/ml TGF-β1+ 5% FBS were established, respectively.The morphology of Pellets was observed under the natural light at 48 hours, 1 week, 2 weeks and 3 weeks after culture.In 3 weeks after culture, the cell structures was observed by hematoxylin-eosin staining, and Calcein-AM/propidium (Calcein-AM/PI) staining was used to assay the cell viability.Real-time fluorescence quantitative PCR and immunofluorescence technology were applied to analyze the expressions of α-smooth muscle actin (α-SMA), fibronectin (FN), type Ⅰ collagen (ColⅠ) and type Ⅲ collagen (Col Ⅲ) mRNA and proteins.RT-PCR was employed to detect the expressions of lumican (LUM) mRNA and keratocan (KERA) mRNA in the cells. Results Cells in Pellet clustered throughout the culture duration.Hematoxylin-eosin staining showed the mass red-dyed collagen fibers in both 0.25 ng/ml TGF-β1+ 5% FBS group and 0.50 ng/ml TGF-β1+ 5% FBS group, and most cells possessed complete structures.The death rate of the cells was (33.60±1.65)% in the 0.25 ng/ml TGF-β1+ 5% FBS group and (30.90±0.78)% in the 0.50 ng/ml TGF-β1+ 5% FBS group, showing an insignificant difference between them (t=0.144, P=0.887). The expressions of α-SMA, FN and Col Ⅲ proteins in 0.25 ng/ml TGF-β1+ 5% FBS group were lower than those in the 0.50 ng/ml TGF-β1+ 5% FBS group (tα-SMA=4.622, P=0.010; tFN =2.973, P=0.040; t Col Ⅲ=7.845, P<0.001), but the expression of Col Ⅰ in 0.25 ng/ml TGF-β1+ 5% FBS group was higher than that in 0.50 ng/ml TGF-β1+ 5% FBS group (tColⅠ=4.022, P=0.016). The ratio of Col Ⅲ/ColⅠ in 0.25 ng/ml TGF-β1+ 5% FBS group was lower than that in the 0.50 ng/ml TGF-β1+ 5% FBS group in both mRNA and protein level (tmRNA =-3.039, P=0.038; tprotein=3.215, P=0.032). The expression of LUM mRNA and KERA mRNA were detected in Pellet at different time points.The expression of LUM mRNA in 0.25 ng/ml TGF-β1+ 5% FBS group increased over time.While in 0.50 ng/ml TGF-β1+ 5% FBS group, the expression of LUM mRNA peaked at 1 week but declined at 2 weeks.The expression of KERA mRNA in two groups were all peaked at 1 week but declined at 2 weeks. Conclusions Low-dose TGF-β1 in Pellet can maintain the normal growth of keratocytes and synthesize ECM.The expression of ECM tends to the normal condition after reducing the concentration of TGF-β1, implying a scarless expression. Key words: Corneal keratocyte; Transforming growth factor-β1; Three-dimensionl model; Bovine

Recovery of Phosphorus and Potassium from Source-Separated Urine Using a Fluidized Bed Reactor: Optimization Operation and Mechanism Modeling

Magnesium potassium phosphate hexahydrate (MgKPO4·6H2O, MPP) crystallization is a promising approach to recover phosphorus (P) and potassium (K). Achievement of large MPP crystal size is still critical for the MPP products utilization. We performed a pilot-scale fluidized bed reactor (FBR) with treatment of synthetic source-separated urine to capture the MPP crystallization. Using the optimized FBR operational parameters, as pH of 10.5, Mg:P molar ratio of 1:1, supersaturation ratio of 3.0, and superficial velocity of 350 cm/min, pellets of high purity (86 ± 2%) with a maximum size of 4 mm were achieved. The removal efficiencies of K and P reached 20–35% and 80–90%, respectively. Furthermore, we proposed a kinetic model to describe the pellet growth. The pellet growth rate was determined as G = 5.046 × 10–9SV0.88S1.96. The model combined with mass balance approach could predict P and K removal efficiencies of the FBR well.