Solving the problem of optimal control of fog diffusion

Solving the problem of optimal control of fog diffusion / Klyomin V.V., Suvorov S.S. // Hydrometeorological Research and Forecasting, 2021, no. 2 (380), pp. 52-65. The paper discusses a possibility of applying one of the fundamental modern optimization methods, namely, the Pontryagin’s method for solving process control problems, whose behavior is described by the diffusion equation. The parabolic diffusion equation is discretized by the method of straight lines and comes to a closed system of ordinary differential equations, which allow finding an optimal control impact in terms of operating speed. The existence of a solution to the problem of optimal control of fog diffusion is proved for the mentioned sampling. The methodology for finding control action switching points is substantiated, the calculations for the revealed two and three switching moments are performed. Keywords: Pontryagin’s method, fog diffusion control, diffusion equation

Engineered shell proteins confer improved encapsulated pathway behavior in a bacterial microcompartment

Bacterial microcompartments are a class of proteinaceous organelles comprising a characteristic protein shell enclosing a set of enzymes. Compartmentalization can prevent escape of volatile or toxic intermediates, prevent off-pathway reactions, and create private cofactor pools. Encapsulation in synthetic microcompartment organelles will enhance the function of heterologous pathways, but to do so, it is critical to understand how to control diffusion in and out of the microcompartment organelle. To this end, we explored how small differences in the shell protein structure result in changes in the diffusion of metabolites through the shell. We found that the ethanolamine utilization (Eut) protein EutM properly incorporates into the 1,2-propanediol utilization (Pdu) microcompartment, altering native metabolite accumulation and the resulting growth on 1,2-propanediol as the sole carbon source. Further, we identified a single pore-lining residue mutation that confers the same phenotype as substitution of the full EutM protein, indicating that small molecule diffusion through the shell is the cause of growth enhancement. Finally, we show that the hydropathy index and charge of pore amino acids are important indicators to predict how pore mutations will affect growth on 1,2- propanediol, likely by controlling diffusion of one or more metabolites. This study highlights the success of two strategies to engineer microcompartment control over metabolite transport: altering the existing shell protein pore via mutation of the pore-lining residues, and generating chimeras using shell proteins with the desired pores.TOC Abstract Graphic

Design of electric field controlled molecular gates mounted on metal–organic frameworks

Molecular gates mounted on MOFs act like nanovalves and control diffusion of molecules.

Efek Antimikroba Pasta Gigi Kandungan Ekstrak Daun Teh 2% (Camellia sinensis) terhadap A. Actinomycetemcomitans

Latar Belakang: Kandungan polifenol (catechin) dalam daun teh diketahui memiliki efek antimikroba terhadap beberapa bakteri. Derajat fermentasi terhadap daun teh akan mempengaruhi daya antimikrobanya. Pasta gigi dengan kandungan ekstrak daun teh segar 2% (Camellia sinensis) diharapkan memiliki efek antimikroba. Tujuan: pengetahuan ini bertujuan untuk mengetahui daya antimikroba pasta gigi kandungan ekstrak teh segar 2% terhadap bekteri A. actinomycetemcomitans. Metode Penelitian: bakteri A. actinomycetemcomitans diperololeh dari laboratorium MikrobiologiFakultas Kedokteran Hewan Universitas Gadjah Mada Yogyakarta. Pengenceran pasta gigi dengan kandungan teh 2% diencerkan menjadi 0,875%; 1,75%; 2,5%; 5%; 10%; dan 100% (kontrol positif). Metode difusi dilakukan pada 15 petri dengan cara masing-masing konsentrasi diambil 100 ul lalu diteteskan dalam setiap sumuran pada media BHI agar yang telah mengandung A. Actinomycetemcomitans kemudian petri dieramkan dalam inkubator selama 24 jam pada suhu 370 C. Pengukuran diameter zone hambatan disekitar sumuran menggunakan jangka sorong, dibantu dngan mikroskop, selanjutnya data dianalisis menggunakan AVANA dan LSD. Hasil menunjukkan daya anti bakteri pasta gigi kandungan ekstrak teh 2% terhadap bakteri A. Actinomycetemcomitans dimulai pada konsentrasi 5% dan terdapat perbedaan yang bermakna (p<0,01) pengaruh konsentrasi terhadap zone hambatan yang dihasilkan. Disimpulkan peningkatan konsentrasi pasta gigikandungan ekstrak teh akan meningkatkan daya antimikroba terhadap bakteri A. Actinomycetemcomitans. Background: Polyphenols (catechins) in tea leaves are known to have antimicrobial effects against some bacteria. Degree of fermentation tea leaves will affect the antimicrobial. Toothpaste containing 2% tea leaves ectract (Camellia sinensis) is expected to have antimicrobial effects. Aim: this study was aimed to determine the antimicrobial effect of tootthpastes contain 2% tea extract on the bacteria A. Actinomycetemcomitans. Method: Aggregatibacter actinomycetemcomitans bacteria from Microbiology Laboratory, Faculty of Veterinary Medicine, Gadjah Mada University Yogyakarta. Tea extract-containing dentrifice was dilluted into 0,875%; 1,75%; 2,5%; 5%; 10%; dan 100% (as positive control). Diffusion method was used on 15 disks. Every concentration of tea extract-containing dentrifice was placed in bottomless cylinder in BHI agar disks that have been heavily seeded with A. Actinomycetemcomitans , then incubated for 24 hours at 370. The diameter of the clear zone of inhibition was measured using sliding caliper and microscope then data were analyzed using AVANA and LSD. The result showed that the antimicrobial effect of tea extract-containing dentrifice was started at 5% and there were significantly difference (p<0,01) effect concentration of tea extract-containing dentrifice on zone of inhibition. In conclusion, increasing concentration of tea extract-containing dentrifice could increase the antimicrobial effect against A. Actinomycetemcomitans.

Research on the Diffusion Law of Oncomelania Along with the Flow Through a Side-Weir

Schistosomiasis is a parasitic disease mostly found in areas along the Changjiang River. Oncomelania is the only intermediate host of schistosomiasis. Oncomelania entering into farmland or the residential zones through the flood discharge or irrigation system is the main reason of spreading schistosomiasis. Therefore it is most essential and effective way to control diffusion of oncomelanias along with flow for preventing epidemic of schistosomiasis disease. In order to simulate the flood discharge when the river dike breaks or the flow from main to branch channel, a side-weir flow system is set up in this paper, And further the flow characteristic is studied by experiment and mathematical modeling. Finally the research on the diffusion law of oncomelania along with side-weir flow is carried out using the experimental test. The results show that oncomelanias do not equally distribute at floodplain areas, but place where flow velocity is small, i.e. in the vortex areas during oncomelanias moving along with side-weir flow. The settling positions of oncomelanias are obtained, which lay a good foundation for eliminating oncomelanias.