Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Design Method for a Higher Order Extended Kalman Filter Based on Maximum Correlation Entropy and a Taylor Network System

This paper proposes one new design method for a higher order extended Kalman filter based on combining maximum correlation entropy with a Taylor network system to create a nonlinear random dynamic system with modeling errors and unknown statistical properties. Firstly, the transfer function and measurement function are transformed into a nonlinear random dynamic model with a polynomial form via system identification through the multidimensional Taylor network. Secondly, the higher order polynomials in the transformed state model and measurement model are defined as implicit variables of the system. At the same time, the state model and the measurement model are equivalent to the pseudolinear model based on the combination of the original variable and the hidden variable. Thirdly, higher order hidden variables are treated as additive parameters of the system; then, we establish an extended dimensional linear state model and a measurement model combining state and parameters via the previously used random dynamic model. Finally, as we only know the results of the limited sampling of the random modeling error, we use the combination of the maximum correlation estimator and the Kalman filter to establish a new higher order extended Kalman filter. The effectiveness of the new filter is verified by digital simulation

Dynamic Self-Assembly of Polyelectrolyte Composite Nanomaterial Film

The aim of this study is not only to investigate the feasibility of using PAH (polyallylamine hydrochloride) and PSS (poly styrene-4-sulfonic acid sodium salt) to prepare a film via a layer by layer self-assembly process entrained with silver nanoparticles, but also to show that the silver nanoparticles crystalline structure can be defined and deposited on the surface of the substrate in the desired alignment structure and manner, which is of great help to research on the LBL method in the cellulose field. The effect of outermost layer variation, assembly layers, and composition of multilayers on the formation of the LBL structure on a nanofibrillated cellulose (NFC)/polyvinyl alcohol (PVA) substrate was investigated. The deposition of PAH and PSS was monitored by Fourier-transform infrared spectroscopy (FT-IR). The morphology of the LBL film layers was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). Furthermore, thermal degradation properties were investigated by thermogravimetric analysis (TGA), and physical properties of multilayer films were tested by a universal mechanical tester. The results reveal that PAH and PSS can be readily deposited on a NFC/PVA substrate by using LBL methodology to prepare self-assembled polyelectrolyte multilayer films. The surface morphology of the LBL composite changed from negative to positive charged depending on the final LBL treatment. Also, according to SEM and AFM analysis, silver nanoparticles were well dispersed in the (PAH/PSS) film, which significantly improved the thermal stability of the composite films

Inclusion of the workshop model in the standardized training of emergency medicine residents

Background: Standardized training of resident physicians (STRP) includes clinical practice, professional required courses, and public required courses, among others. Of them, clinical practice is the most important as it allows residents to implement what they have learned in theoretical education to practice. Clinical practice includes different teaching methods, such as traditional lectures, bedside teaching, and workshops, and each method has its advantages and disadvantages in different situations of interest. Emergency medicine (EM) focuses on the diagnosis and treatment of urgent medical conditions and entails several emergency procedures. In this study, we aimed to compare the effects of workshop-based STRP and traditional STRP on emergency physicians. Methods: Overall, 125 residents who received STRP in EM between January and December 2021 were selected and randomly divided into two groups: the control group (n = 60; received traditional teaching) and the intervention group (n = 65; received workshop-based training). The theoretical performance, operative performance, and satisfaction of both groups were compared and analyzed. Results: Regarding theoretical assessment, the scores of airway management, cardiopulmonary resuscitation, and trauma management in the intervention group were 4.81 (t = 5.82, p < 0.001), 6.90 (t = 7.72, p < 0.001), and 5.25 (t = 6.14, p < 0.001), respectively. Regarding skill assessment, the scores for the same items in the intervention group were 4.43 (t = 5.30, p < 0.001), 4.55 (t = 5.61, p < 0.001), and 5.62 (t = 6.65, P < 0.001), respectively. Regarding satisfaction evaluation, the scores in the intervention group were 1.99 (t = 6.03, p < 0.001), 1.98 (t = 6.41, p < 0.001), and 1.96 (t = 6.14, p < 0.001), respectively. Overall, the scores were higher in the intervention group than in the control group. Conclusion: The workshop training model effectively improves the theoretical knowledge and practical skills of EM residents undergoing standardized training. The residents found the training and its outcomes satisfactory, ultimately improving their emergency response and first-responder skills

Experimental Study on Stress Uniformity and Deformation Behavior of Coals with Different Length-to-Diameter Ratios under Dynamic Compression

In this study, a uniaxial impact compression test was performed on coal samples with length-to-diameter L/D ratios of 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1 using a Φ 50 mm split Hopkinson pressure bar (SHPB) test system. This study researched the stress uniformity and deformation behavior of coal samples with different L/D ratios during dynamic compression, defined the stress equilibrium coefficient ξ, proposed a new method for determining whether a sample meets the stress uniformity hypothesis, and obtained the critical L/D ratio of 0.6 and the optimal L/D ratio of 0.3 or 0.4 for coal samples to obtain the stress equilibrium. The experimental results showed that the dynamic stress-strain curve of coal had an elastic stage, a plastic stage, and a failure stage. As the L/D ratio increased, the proportion of the elastic stage to the prepeak curve of the samples declined progressively; with an increase in the L/D ratio, the peak part of the curve also changed from “sharp” to “stagnated,” while an increase in the plasticity led to strain softening. As the L/D ratio of the samples increased, the average strain rate decreased approximately as a power function, and the decreasing trend was gradually reduced from 296.49 s−1 (L/D=0.3) to 102.85 s−1 (L/D=1), with a reduction of approximately 65.31%. With an increase in the L/D ratio, the peak strain gradually decreased exponentially. This study concluded that the SHPB test protocol design is of a certain reference value for low-density, low-strength, heterogeneous brittle materials, such as coal

Rh-Catalyzed Asymmetric Hydrogenation of Cyclic α‑Dehydroamino Ketones

Catalyzed by a rhodium complex of P-stereogenic diphosphine trichickenfootphos, five-membered cyclic α-dehydroamino ketones bearing endocyclic acyl and endocyclic vinyl groups were hydrogenated to give chiral α-amino ketones with quantitative conversions and excellent enantioselectivities

Analysis of Leaf and Soil Nutrients, Microorganisms and Metabolome in the Growth Period of <i>Idesia polycarpa</i> Maxim

Idesia polycarpa Maxim is an emerging oil plant species. Understanding its microecological characteristics and internal mechanisms can serve as a basis for field management and the screening and application of growth-promoting bacteria during the growth phase of young trees. This study used three-year-old young I. polycarpa to analyze the tree’s root morphology, soil, and leaf nutrient status variations from May to October. In addition, differences in the rhizosphere soil, leaf metabolites, and microorganisms were observed. The results showed that, from May to October, the total nitrogen (TN) in the soil significantly decreased, whereas the TN, total potassium (TK), and total phosphorus (TP) in the leaves differed (p p p Pedomicrobium sp., Talaromyces sp., Penicillium sp., and D-Mannitol 2

Evaluation of Fine Root Morphology and Rhizosphere Environmental Characteristics of the Dioecious <i>Idesia polycarpa</i> Maxim

To explore the differences in the fine root characteristics and rhizosphere environment of male and female Idesia polycarpa Maxim at different stages, 7-year-old male and female I. polycarpa were used as plant materials. The fine root characteristics were measured with a root scanner, and rhizosphere soil was collected at the flowering stage (May), fruit accumulation stage (July), and fruit maturity stage (October). In addition, this study analyzed the soil nutrient characteristics of these conditions at different stages. At the same time, Illumine high-throughput sequencing technology and gas chromatography–tandem mass spectrometry (GC–MS) technology were used to analyze the rhizosphere microbes and metabolites of male and female plants at different stages. The results showed that the total root length, surface area, total volume, root tip number, and total average diameter of the fine root of female plants were larger than those of male plants, and the difference reached its maximum in the fruit material accumulation stage. Total carbon (TC) and total nitrogen (TN) content in the rhizosphere soil of male and female plants significantly differed over multiple stages, while available soil nitrogen and potassium content significantly differed during fruit ripening. The rhizosphere microbial composition of male and female plants was similar, and the dominant bacteria in the rhizosphere soil of each stage were Proteobacteria, Acidobacteria, Ascomycota, and Mortierellomycota. The relative abundance of Bacillus, Arthrobacter, Volutella, and Neocosmospora in rhizosphere soil at different stages differed between male and female plants. Combined with the OPLS-DA model and database retrieval, 29 significantly different metabolites, most of which were carbohydrates, were detected in the rhizosphere soil of male and female plants. Moreover, there were more significant metabolites in the rhizosphere soil at the flowering stage than in the fruit ripening stage. Through RDA analysis, available potassium (AK), Pedomicrobium, Chaetomium, and Glucose 1 had the greatest influence on fine root traits of I. polycarpa. The results indicated that the fine root traits were negatively correlated with AK and rhizosphere metabolites. Moreover, positive correlations were found with rhizosphere microorganism traits. The above results laid a foundation for the field management of I. polycarpa and the screening and application of rhizosphere growth-promoting bacteria resources