Use of modified Richards model to predict isothermal and non-isothermal microbial growth

Efficient Removal of Dental Plaque Biofilm from Training Typodont Teeth via Water Flosser

Plaque biofilms play critical roles in the development of dental caries. Mechanical plaque control methods are considered to be most effective for plaque removal, such as brushing teeth or using flosser. Recently, water flosser has been paid much attention. Here, we tested the ability of a water flosser to remove the adhered sucrose and the dental plaque biofilms formed by Streptococcus mutans, Streptococcus sanguinis, and Actinobacillus viscosus. We found that the residual sucrose concentration was 3.54 mg/mL in the control group, 1.75 mg/mL in the syringe group (simulating the ordinary mouthwash), and 0 mg/mL in water flosser group. In addition, the residual bacterial concentration was 3.6 × 108 CFU/mL in the control group, 1.6 × 107 CFU/mL in the syringe group, and only 5.5 × 105 CFU/mL in the water flosser group. In summary, water flosser is effective for cleaning the teeth, which may have significant potential in preventing dental caries and maintaining oral health.

CO2 capture and lipid production performance of microalgae in the S-shaped photobioreactor under different culture modes

An S-shaped photobioreactor was designed by adding grooves and baffles in the traditional photobioreactor to improve the culture efficiency of microalgae. After that, the parameters of the characterization of the S-shaped photobioreactor, such as the mixing time, gas holdup, and gas-liquid mass transfer coefficient, were determined. The biomass, lipid production rate, and average CO₂ capture rate of microalgae were then analyzed under different culture modes. Finally, the feasibility of using digested piggery wastewater combined with simulated flue gas was explored as a culture mode for the microalgae and the lipid properties of the microalgae were analyzed. The results revealed that, at a flow rate of 0.08 vvm, the mixing time was reduced by 8.5 s, the gas hold-up increased by 44.6% and the gas-liquid mass transfer ability was also improved. Improvements were also observed in the biomass values, lipid production rate, and average CO₂ capture rate of the microalgae under different culture conditions, with respective values reaching 0.23 g·(L·d)^-1, 70.28 mg·(L·d)^-1, and 0.43 g·(L·d)^-1 under the mixotrophic mode. Additionally, digested piggery wastewater combined with the simulated microalgae flue gas culture was determined to be feasible. The biomass, lipid production rate, and the average CO₂ capture rate of microalgae, the values of which were 0.22 g·(L·d)^-1, 52.55 mg·(L·d)^-1, and 0.41 g·(L·d)^-1, respectively. Lipid was observed to have the potential to produce high-quality biofuel.

Performance of 45 Non-Linear Models for Determining Critical Period of Weed Control and Acceptable Yield Loss in Soybean Agroforestry Systems

A family of Sigmoidal non-linear models is commonly used to determine the critical period of weed control (CPWC) and acceptable yield loss (AYL) in annual crops. We tried to prove another non-linear model to determine CPWC and AYL in a soybean agroforestry system with kayu putih. The three-year experiment (from 2019–2021) was conducted using a randomised complete block design factorial with five blocks as replications. The treatments comprised weedy and weed-free periods. Non-linear models comprised 45 functions. The results show that the Sigmoidal and Dose-Response Curve (DRC) families were the most suitable for estimating CPWC and AYL. The best fitted non-linear model for weedy and weed-free periods in the dry season used the Sigmoidal family consisting of the Weibull and Richards models, while in the wet season the best fit was obtained using the DRC and Sigmoidal families consisting of the DR-Hill and Richards models, respectively. The CPWC of soybean in the dry season for AYL was 5, 10, and 15%, beginning at 20, 22, and 24 days after emergence (DAE) and ended at 56, 54, and 52 DAE. The AYL in the wet season started at 20, 23, and 26 DAE and ended at 59, 53, and 49 DAE.

Modeling Biomass and Nutrients in a Eucalyptus Stand in the Cerrado

The prediction of biological processes, which involve growth and plant development, is possible via the adjustment of mathematical models. In forest areas, these models assist in management practices, silviculture, harvesting, and soil fertility. Diameter, basal area, and height are predictors of volume and biomass estimates in forest stands. This study utilized different non-linear models for estimating biomass and nutrient values in the aerial biomass and roots of an unmanaged eucalypt stand in Cerrado dystrophic soil. It was hypothesized that the models would estimate the nutrients of the aboveground biomass and roots after meeting the selection and validation criteria. By statistical analysis of the parameters and subsequent validation, the Schumacher–Hall model was presented to be the best fit for biomass and nutrients. This result confirmed the ability of different variables, including diameter, basal area, and height, to be predicted. Estimating the nutrient values in the aboveground biomass and roots allowed a better understanding of the quality of the vegetal residues that remained in the soil. For dystrophic soils, which occur in the Cerrado, these estimates become even more relevant.

Temperature dependent morphological changes on algal growth and cell surface with dairy industry wastewater: an experimental investigation

In the present study, influence of temperature and dairy industry waste water (DIWW) concentration on the growth of Chlorella pyrenoidosa has been done along with the thermodynamic analysis of different functions viz. change in enthalpy (∆H), change in entropy (∆S), free energy change (∆G), and activation energy (E _a) to study the impact on cell size distribution and morphological changes. Among the studied temperatures, higher biomass productivity was observed at 35 °C at 75% of DIWW. Thermodynamic analysis showed the spontaneous and exothermic nature of growth of C. pyrenoidosa. Experimental data have significantly proven the kinetic and thermodynamics functions with 35 °C temperature, ∆H (- 46.78 kJ mol^-1), ∆S (- 0.10 kJ mol^-1), ∆G (- 14.8 kJ mol^-1), and E _a (49.28 kJ mol^-1). At this temperature, size distribution showed maximum percentage (48%) cells were of 6540 nm, whereas the minimum percentage (3%) cells were of 2750 nm. SEM-EDX study revealed that increase in temperature leads to increase in roughness and elemental deposition of metal on cell surface.

Modelagem e simulação do crescimento de Talaromyces flavus em abacaxi: uma integração entre modelos cinéticos e de fenômenos de transporte

Resumo O estudo da dinâmica de crescimento de microrganismos em alimentos é de vital importância para a extensão da vida de prateleira desses produtos. No presente trabalho, um modelo de cinética microbiológica descrevendo o crescimento de Talaromyces flavus em abacaxi foi integrado com um modelo térmico. O modelo integrado foi utilizado para simular a shelf life do produto em processos de aquecimento. Os experimentos cinéticos foram realizados em 4 temperaturas distintas (de 20 °C a 35 °C) e índices estatísticos foram empregados para a seleção dos melhores modelos primários e secundários. O modelo térmico baseou-se na solução analítica da equação da difusão de calor para placas planas e cilindros infinitos. Observou-se que o modelo de Gompertz modificado (BF=1,003, AF=1,049, RSS=3,687 e RMSE=1,286), juntamente com os modelos de raiz quadrada estendida (BF=0,999, AF=1,012 e RSS=0,2684) e polinomial de ordem 2 (BF=0,991, AF=1,011, RSS=0,006 e RMSE=0,078) foram os modelos mais satisfatórios. O modelo cinético foi validado em condições estáticas e dinâmicas de temperatura (em dois cenários distintos) para assegurar que pudesse ser integrado com as equações de transferência de calor. As simulações demonstraram acréscimo de 23,3% na vida de prateleira com o aumento do comprimento do produto (de 2 para 30 cm) e acréscimo de 88,2% com diminuição da temperatura do ar ambiente (de 34 °C para 22 °C). Efeitos menos pronunciados foram obtidos variando o diâmetro do produto e a velocidade do ar ambiente.