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

Acetic acid-assisted fabrication of hierarchical flower-like Bi2O3 for photocatalytic degradation of sulfamethoxazole and rhodamine B under solar irradiation

With the assistance of acetic acid (CH3COOH), a novel 3D flower-like Bi2O3 was synthesized via hydrothermal process followed by calcination. For the first time, the role of CH3COOH as a capping agent in the formation of flower-like structure was investigated. The as-prepared flower-like Bi2O3 had a high activity on the degradation of sulfamethoxazole (SMX) under simulated solar light irradiation due to the narrow band gap of 2.69eV, high percentage of β-Bi2O3 as well as high intensity of polar facets (120) and (200). Meanwhile, the photocatalytic degradation followed apparent pseudo-first-order kinetics. The rate constant (k) increased from 0.7×10-2 to 3.0×10-2min-1 with the catalyst loading varying from 0.5 to 2.0gL-1. Increasing pH values from 3 to 11 led to the decrease of k from 2.2×10-2 to 0.2×10-2min-1, which could be attributed to the electrostatic adsorption between SMX molecules and Bi2O3. The radical quenching experiments showed both direct (h+) and indirect oxidation (OH and O2-) happened in this process.Accepted versio

One-step construction of heterostructured metal-organics@Bi2O3 with improved photoinduced charge transfer and enhanced activity in photocatalytic degradation of sulfamethoxazole under solar light irradiation

A facile one-step assembly method was developed for the preparation of metal-organics @Bi2O3 composites for photocatalysis. Two kinds of metal-organics (Ti-bdc and Cu-btc)@Bi2O3 composites were synthesized via the coordination of btc3-/bdc2- and metal ions (Ti4+/Cu2+) as well as OH on the surface of Bi2O3. Compared with pure Bi2O3, Ti-bdc@Bi2O3 shows a 1.7 times higher photocatalytic activity in the degradation of sulfamethoxazole (SMX) under a simulated solar irradiation with a cumulative removal of 62% within 60 min. The high photocatalytic activity could be attributed to the high charge separation, enhanced electron transfer as well as the low recombination rate of photo-generated electrons and holes due to the construction of hetero-structures. The stability test showed that Ti-bdc@Bi2O3 is more stable in water than Cu-btc@Bi2O3. Furthermore, through the radical-trapping experiments and main intermediates detection, it is demonstrated that the photo-generated holes as well as the OH and O2- formed dominate the photocatalytic decomposition of SMX. These findings demonstrate the potential usage of a facile method to synthesize metal-organics and metal oxides composites, some of which possess high water stability and thus could be employed for water treatment

Alemtuzumab-Based Reduced-Intensity Conditioning Allogeneic Transplantation for Myeloma and Plasma Cell Leukemia - A Single-Institution Experience

BACKGROUND: Reduced-intensity conditioning allogeneic transplantation for myeloma is associated with lower non-relapse mortality and higher relapse rates in comparison with myeloablative conditioning transplants. PATIENTS AND METHODS: We have retrospectively audited 19 patients with myeloma or primary plasma cell leukemia who received allogeneic transplantation with a uniform alemtuzumab-based reduced-intensity conditioning protocol. These patients had not been treated with bortezomib or lenalidomide before transplantation. RESULTS: The treatment-related mortality at 1 year was (4/19) 21% with low incidence of graft-versus-host disease (6%) and 2-year progression-free survival and overall survival rates of 35% and 42%, respectively. CONCLUSION: Progression-free survival in this cohort of patients is comparable to previously published data of reduced-intensity conditioning allogeneic transplantation in myeloma. However, there is no plateau observed on the survival curves with a significant transplant-related mortality of 21%. Therefore, alemtuzumab-based allogeneic transplantation cannot be recommended as standard practice outside of clinical trials for treatment of myeloma