Nanomotion technology in combination with machine learning: a new approach for a rapid antibiotic susceptibility test for Mycobacterium tuberculosis.

Nanomotion technology is a growth-independent approach that can be used to detect and record the vibrations of bacteria attached to cantilevers. We have developed a nanomotion-based antibiotic susceptibility test (AST) protocol for Mycobacterium tuberculosis (MTB). The protocol was used to predict strain phenotype towards isoniazid (INH) and rifampicin (RIF) using a leave-one-out cross-validation (LOOCV) and machine learning techniques. This MTB-nanomotion protocol takes 21 h, including cell suspension preparation, optimized bacterial attachment to functionalized cantilever, and nanomotion recording before and after antibiotic exposure. We applied this protocol to MTB isolates (n = 40) and were able to discriminate between susceptible and resistant strains for INH and RIF with a maximum sensitivity of 97.4% and 100%, respectively, and a maximum specificity of 100% for both antibiotics when considering each nanomotion recording to be a distinct experiment. Grouping recordings as triplicates based on source isolate improved sensitivity and specificity to 100% for both antibiotics. Nanomotion technology can potentially reduce time-to-result significantly compared to the days and weeks currently needed for current phenotypic ASTs for MTB. It can further be extended to other anti-TB drugs to help guide more effective TB treatment

Accurate and rapid antibiotic susceptibility testing using a machine learning-assisted nanomotion technology platform.

Antimicrobial resistance (AMR) is a major public health threat, reducing treatment options for infected patients. AMR is promoted by a lack of access to rapid antibiotic susceptibility tests (ASTs). Accelerated ASTs can identify effective antibiotics for treatment in a timely and informed manner. We describe a rapid growth-independent phenotypic AST that uses a nanomotion technology platform to measure bacterial vibrations. Machine learning techniques are applied to analyze a large dataset encompassing 2762 individual nanomotion recordings from 1180 spiked positive blood culture samples covering 364 Escherichia coli and Klebsiella pneumoniae isolates exposed to cephalosporins and fluoroquinolones. The training performances of the different classification models achieve between 90.5 and 100% accuracy. Independent testing of the AST on 223 strains, including in clinical setting, correctly predict susceptibility and resistance with accuracies between 89.5% and 98.9%. The study shows the potential of this nanomotion platform for future bacterial phenotype delineation

Justify your alpha

Benjamin et al. proposed changing the conventional “statistical significance” threshold (i.e.,the alpha level) from p ≤ .05 to p ≤ .005 for all novel claims with relatively low prior odds. They provided two arguments for why lowering the significance threshold would “immediately improve the reproducibility of scientific research.” First, a p-value near .05provides weak evidence for the alternative hypothesis. Second, under certain assumptions, an alpha of .05 leads to high false positive report probabilities (FPRP2 ; the probability that a significant finding is a false positive

Justify your alpha

In response to recommendations to redefine statistical significance to p ≤ .005, we propose that researchers should transparently report and justify all choices they make when designing a study, including the alpha level

Removal of chlorophenols from aqueous solutions by sorption onto walnut, pistachio and hazelnut shells

The efficiency of walnut, pistachio and hazelnut shells to remove three monochlorophenols (2-CP, 3-CP and 4-CP) from aqueous solutions has been investigated. To describe the kinetic data pseudo-first and pseudo-second order models were used. The kinetics data were fitted better into the pseudo-second order model with the coefficient of determination values greater than 0.99. The k2 &ensp values increased in the order 4-CP < 3-CP < 2-CP. Sorption was also analyzed as a function of solution concentration at equilibrium. The experimental data received were found to be well described by the Freundlich isotherm equation. Effectiveness of chlorophenols removal from water on the walnut, pistachio and hazelnut shells was comparable. Individual differences in sorption of monochlorophenols were also negligible

Comparison of Activated Carbon and Carbon Nanotubes as Adsorbents for the Removal of 2,4-dichlorophenol from Water

Celem prezentowanej pracy było porównanie węgla aktywnego i nanorurek węglowych jako adsorbentów do usuwania 2,4-dichlorofenolu z wody. Do badań wybrano węgiel aktywny L2S Ceca o powierzchni właściwej 945 m2/g oraz wielościenne nanorurki węglowe o niemodyfikowanej powierzchni (SBET = 181 m2/g). Zbadano zarówno kinetykę adsorpcji, jak i adsorpcję w stanie równowagi. 2,4-dichlorofenol adsorbował się szybciej na nanorurkach niż na węglu aktywnym, jednak z o wiele mniejszą skutecznością. Po osiągnięciu równowagi (po 2 godzinach) na nanorurkach zaadsorbowało się 19% chlorofenolu, natomiast na węglu aktywnym (po 5 godzinach) prawie 91%. Kinetyka przebiegała zgodnie z modelem pseudo II rzędu, współczynniki korelacji R2 wynosiły powyżej 0,99. Izotermy adsorpcji 2,4-dichlorofenolu w warunkach statycznych zostały opisane modelem Langmuira. Zastosowano pięć różnych form prostoliniowych równania Langmuira. Uzyskane wysokie wartości współczynników korelacji świadczą o dobrym dopasowaniu modelu teoretycznego do izoterm doświadczalnych. Wartości stałych qm są wielokrotnie wyższe dla węgla aktywnego niż nanorurek węglowych, co dowodzi, że 2,4-dichlorofenol adsorbuje się o wiele lepiej na węglu aktywnym niż na wielościennych nanorurkach węglowych.Adsorption is one of the well-established and effective techniques for the removal of chlorophenols from natural environment. The aim of the present study was to compare the activated carbon and carbon nanotubes as adsorbents for the removal of 2,4-dichlorophenol from water. As adsorbent the activated carbon L2S Ceca (SBET = 945 m2/g) and unmodified multi-walled carbon nanotubes (SBET = 181 m2/g) were chosen. Both the kinetic and adsorption equilibria were investigated. Adsorption quantities were determined by high- -performance liquid chromatography with diode-array detector. The kinetic experiments were carried out for initial concentration of 2,4-dichlorophenol 1.0 mmol/dm3 and 0.05 g of adsorbent. The results showed that 2,4-dichlorophenol was adsorbed more rapidly on carbon nanotubes than onto activated carbon. Adsorption equilibrium was achieved after 2 and about 5-6 hours on carbon nanotubes and activated carbon, respectively. In order to investigate the kinetics of adsorption of 2,4-dichlorophenol the constants were determined in terms of the pseudo-first-order and pseudo-second-order equations. The pseudo-second-order model fits the experimental data quite well with the correlation coefficients greater than 0.99. These results indicate that the adsorption system belongs to the second-order kinetic model. In adsorption isotherm studies, solutions of 2,4-dichlorophenol with different initial concentrations (0.1, 0.5, 1.0, 1.5, 2.0 and 2.5 mmol/dm3) were shaken for 3 hours (carbon nanotubes) or 6 hours (activated carbon). The adsorption data were analyzed by a regression analysis to fit the five linearized expressions of Langmuir isotherm model. The values of the coefficient of correlation (>0.99) obtained from Langmuir 1, 2 and 5 expressions indicate that there is strong positive evidence that the adsorption of 2,4-dichlorophenol on activated carbon and carbon nanotubes follows the Langmuir isotherm. The lower coefficient of correlation values for Langmuir 3 and 4 linear expressions, suggest that it is not appropriate to use this type of linearization. Significantly higher values of qm determined from the Langmuir plots indicate that the 2,4-dichlorophenol is adsorbed better on activated carbon than multi-walled carbon nanotubes

The influence of surface chemistry of the activated carbons on the adsorption of 2,4-dichlorophenoxyacetic acid

The aim of this study was to investigate the effect of surface chemistry of the activated carbons on the adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D). The 2,4-D was adsorbed on non-modified Norit R3-ex activated carbon (AC-NM) as well as on activated carbons modified by oxidation with concentrated nitric acid (AC-HNO3) and by heat treatment in ammonia at 900°C (AC-NH3). Adsorption isotherms of the 2,4-D on the activated carbons were analyzed using the Freundlich, Langmuir and Langmuir-Freundlich models. The Langmuir equation was slightly better fitted to the experimental data with the correlation coefficients better than 0.99. The values of the Langmuir maximum adsorption capacity (qm) were 2.945, 2.740 and 3.297 mmol/g for the AC-NM, AC-HNO3 and AC-NH3 activated carbons, respectively. The adsorption capacity of the activated carbons increased in the order: AC-HNO3 3. The best adsorbent was activated carbon with basic properties, while the worst adsorption properties were observed for the activated carbon with acidic properties. The acid treatment of activated carbon produced a large number of oxygen-containing functional groups on the carbon surface as it increases its acidic property and, in consequence, reduces the adsorption of the 2,4-D. The treatment of activated carbon with ammonia at high temperature leads to the formation of nitrogen-containing groups. The basic properties of the carbon surface enhance the interaction between activated carbon and acid molecules (dipole-dipole, H-bonding, covalent bonding) causing the increased adsorption of the 2,4-D from water. The effect of pH on the adsorption of 2,4-D onto activated carbons was also studied. The adsorption of the 2,4-D was almost constant at the pH range of 2.0-2.6 and decreased with the further increasing in the pH. The solution pH determines the adsorbent charge and the protonation or dissociation of the adsorbate. The pKa of 2,4-D is 2.8, and at a pH greater than the pKa value, the herbicide existed predominantly in anionic forms. As the pH increased, the degree of dissociation of 2,4-D increased, thereby making it more negatively charged. The values of the point of zero charge (pHPZC) were 6.10, 3.35 and 7.85 for the AC-NM, AC-HNO3 and AC-NH3 activated carbons, respectively. At pH of less than the pHPZC, the surface of the carbon had a net positive charge; at a pH greater than pHPZC, the surface had a net negative charge. The large reduction in the 2,4-dichlorophenoxyacetic acid adsorption at highly basic conditions can be attributed to the electrostatic repulsion between the negatively charged activated carbons and the dissociated 2,4-D molecules. The experimental results demonstrate that the surface chemistry of the activated carbons affects significantly the adsorption of the 2,4-D and should be taken into account when choosing an adsorbent for the removal of the herbicide from water.Celem pracy było zbadanie wpływu chemii powierzchni węgli aktywnych na adsorpcję kwasu 2,4-dichlorofenoksyoctowego (2,4-D) z wody. Adsorpcję prowadzono na węglu Norit R3-ex o niemodyfikowanej powierzchni (AC-NM), na węglu utlenionym stężonym kwasem azotowym(V) (AC-HNO3) oraz węglu wygrzewanym w amoniaku w temperaturze 900°C (AC-NH3). Do opisu adsorpcji zastosowano równania Freundlicha, Langmuira i Langmuira-Freundlicha. Pojemność adsorpcyjna badanych węgli wzrastała w kolejności AC-HNO33. Najlepszym adsorbentem okazał się węgiel aktywny o zasadowym charakterze (AC-NH3), najgorsze właściwości adsorpcyjne zaobserwowano dla węgla aktywnego o kwaśnych właściwościach (AC-HNO3). Zbadano również wpływ pH na adsorpcję 2,4-D z wody. Adsorpcja zmniejszała się wraz ze wzrostem pH roztworu, spadek ten był skorelowany z właściwościami kwasowo-zasadowymi powierzchni adsorbentów. Wyniki pokazały, że chemia powierzchni węgli aktywnych jest ważnym czynnikiem wpływającym na adsorpcję 2,4-D z wody i powinna być brana pod uwagę przy wyborze adsorbentu do usuwania herbicydu z wody w celu zmaksymalizowania skuteczności procesu oczyszczania

Influence of the number of chlorine atoms in the molecules of chlorophenoxyacetic acids on its adsorption from aqueous solutions on activated carbon

Three phenoxyacetic acids of various number of chlorine atoms in the molecule (PA, 4-CPA, 2,4-D) were selected to adsorption experiments. Adsorption of these compounds from aqueous solutions has been studied using commercial activated carbon F300 (Chemviron). The kinetic data were examined with the pseudo-first-order and pseudo-second-order models, and were found to follow closely the pseudo-second-order kinetic model. With increase in the initial solution concentration rate constants k2 diminish for each adsorbate and with increase in the number of Cl atoms in phenoxyacetic acid molecule rate constants k2 decrease for each initial solution concentration. Adsorption equilibrium data were analyzed and were fitted well using Freundlich isotherm in the studied concentration range. With increase in the number of Cl atoms in phenoxyacetic acid molecules the Freundlich equation constants KF and n decrease. Presence of electrolyte (Na2SO4) in aqueous solutions of phenoxyacids enhances their adsorption.Do badań adsorpcyjnych wybrano trzy kwasy fenoksyoctowe o różnej liczbie atomów chloru w cząsteczce (PA, 4-CPA, 2,4-D). Adsorpcję tych związków z roztworów wodnych badano stosując handlowy węgiel aktywny F-300 (Chemviron). Dane kinetyczne analizowano z użyciem modeli pseudo-pierwszego i pseudo-drugiego rzędu i stwierdzono, że dobrze spełniają kinetyczny model pseudo-drugiego rzędu. Wraz ze wzrostem początkowego stężenia roztworu wartości stałej szybkości k2 zmniejszały się w przypadku każdego adsorbatu. Także wraz ze wzrostem liczby atomów chloru w cząsteczce kwasu fenoksyoctowego zmniejszały się wartości stałej szybkości k2 przy każdym stężeniu początkowym adsorbatu. Analizowano także dane adsorpcji w funkcji równowagowego stężenia roztworu. Stwierdzono, że w zakresie stosowanych stężeń, adsorpcja była dobrze opisywana przy użyciu izotermy Freundlicha. Wraz ze wzrostem liczby atomów chloru w cząsteczce kwasu fenoksyoctowego wartości stałych równania Freundlicha (KF i n) malały. Stwierdzono też, obecność elektrolitu (Na2SO4) w roztworach fenoksykwasów powodowała wzrost ich adsorpcji

Kinetyka adsorpcji chloroorganicznych zanieczyszczeń wody z roztworów wieloskładnikowych na węglu aktywnym

A comparative study of adsorption kinetics in the systems multicomponent aqueous solutions of selected chlorophenols (2-CP, 3-CP, 4-CP) and chlorophenoxy herbicides (2,4-D, MCPA) - activated carbon (F-300) has been performed. The concentrations of all adsorbates in the aqueous phase were determined using high performance liquid chromatography (HPLC). The applicability of two kinetic models, the pseudo-first and pseudo-second order models, for the experimental data was examined. The adsorption kinetics was better described by the pseudo-second order model with correlation coefficients R2 ≥ 0.997 for all adsorbates.Wykonano badania porównawcze szybkości adsorpcji z wieloskładnikowych wodnych roztworów wybranych chlorofenoli (2-CP, 3-CP, 4-CP) i herbicydów chlorofenoksyoctowych (2,4-D, MCPA) na granulowanym węglu aktywnym (F-300). Stężenia wszystkich adsorbatów w fazie wodnej oznaczano za pomocą wysokosprawnej chromatografii cieczowej (HPLC). Zbadano przydatność dwóch modeli kinetycznych: pseudopierwszego i pseudodrugiego rzędu do opisu wyników eksperymentalnych. Uzyskane rezultaty pokazują, że kinetykę adsorpcji lepiej opisuje równanie pseudodrugiego rzędu, co potwierdziły większe wartości współczynnika korelacji dla wszystkich adsorbatów (R2 ≥ 0,997)