A general model for multiple substrate biodegradation. Application to co-metabolism of structurally non-analogous compounds

The availability of multiple carbon/energy sources, as is common in wastewater treatment plants, often enhances the biodegradation of recalcitrant compounds. In this paper, we classify and model different modes of multiple substrate utilization in a systematic way, using the concept of synthesizing unit. According to this concept, substrates can be substitutable or complementary; their uptake (or processing) can be sequential or parallel. We show how the different modes of multiple substrate interaction can be described by a single general model. From the general model, we derive simple expressions for co-metabolism of substrates that are not structurally analogous. Both the general and the specific co-metabolism model have the advantage that they can be used in combination with any microbial growth model. To test the co-metabolism model's realism, we confront it with experimental data. The results attained with the co-metabolism model support that the general model constitutes a useful framework for modeling aspects of multiple substrate utilization.     

1mm内径HPLC整体柱用于蛋白质的高效分离

介绍了1mm内径的聚苯乙烯-二乙烯基苯整体柱用于液相色谱反相梯度高效分离完整的蛋白质。文中详细研究了柱温、流速和梯度时间等对峰宽和峰容量的影响。在最优色谱条件下该柱高效地反相分离了核糖核酸酶A、肌红蛋白和碳酸酐酶的蛋白质混合物以及大肠杆菌提取蛋白。     

Development and validation of a higher-throughput equilibrium dialysis assay for plasma protein binding

We describe the practical aspects of developing a semiautomated, higher-throughput plasma protein binding (PPB) assay. The assay has a capacity of 32 PPB measurements per screen using triplicate incubations per measurement, and it is flexible with respect to the number of compounds and the number of plasma types used. The described method is based on the 48-well format rapid equilibrium dialysis (RED) device in combination with a robotic liquid handling platform and quantitative bioanalysis. The RED device method was optimized with respect to equilibration time. Method validation was performed by comparison of results from the semiautomated RED PPB assay with both of those obtained using an alternative, manual equilibrium dialysis method and with literature values. Propranolol and warfarin were used as control compounds. We have modeled the effect of dialysis membrane leakage on the measured unbound fraction and implemented a test for measuring protein content in the buffer compartment to confirm the integrity of each insert of the RED device. With the described method, it is possible to screen a relatively large number of compounds for PPB in a drug discovery environment.     

Metallic Contact between MoS2 and Ni via Au Nanoglue

A critical factor for electronics based on inorganic layered crystals stems from the electrical contact mode between the semiconducting crystals and the metal counterparts in the electric circuit. Here, a materials tailoring strategy via nanocomposite decoration is carried out to reach metallic contact between MoS₂ matrix and transition metal nanoparticles. Nickel nanoparticles (NiNPs) are successfully joined to the sides of a layered MoS₂ crystal through gold nanobuffers, forming semiconducting and magnetic NiNPs@MoS₂ complexes. The intrinsic semiconducting property of MoS₂ remains unchanged, and it can be lowered to only few layers. Chemical bonding of the Ni to the MoS₂ host is verified by synchrotron radiation based photoemission electron microscopy, and further proved by first‐principles calculations. Following the system's band alignment, new electron migration channels between metal and the semiconducting side contribute to the metallic contact mechanism, while semiconductor–metal heterojunctions enhance the photocatalytic ability.     

Modeling receptor kinetics in the analysis of survival data for organophosphorus pesticides

Acute ecotoxicological tests usually focus on survival at a standardized exposure time. However, LC50's decrease in time in a manner that depends both on the chemical and on the organism. DEBtox is an existing approach to analyze toxicity data in time, based on hazard modeling (the internal concentration increases the probability to die). However, certain chemicals elicit their response through (irreversible) interaction with a specific receptor, such as inhibition of acetylcholinesterase (AChE). Effects therefore do not solely depend on the actual internal concentration, but also on its (recent) past. In this paper, the DEBtox method is extended with a simple mechanistic model to deal with receptor interactions. We analyzed data from the literature for organophosphorus pesticides in guppies, fathead minnows, and springtails. Overall, the observed survival patterns do not clearly differ from those of chemicals with a less-specific mode of action. However, using the receptor model, resulting parameter estimates are easier to interpret in terms of underlying mechanisms and reveal similarities between the various pesticides. We observed thatthe no-effect concentration estimated from the receptor model is basically identical to the value from standard DEBtox, illustrating the robustness of this summary statistic.     

Developments in the management of flood defences and hydraulic infrastructure in the Netherlands

This article highlights recent developments in flood risk management in the Netherlands and presents approaches for reliability analysis and asset management for flood defences and hydraulic infrastructure. The functioning of this infrastructure is of great importance for the country as large parts of it are prone to flooding. Based on a nationwide flood risk assessment, new safety standards for flood defences have been derived in the form of maximal acceptable failure probabilities. A framework for the reliability-based analysis of the performance of hydraulic infrastructure is introduced. Within this context, various challenges are discussed, such as the dynamic nature of loads, resistance and reliability requirements over time. Various case studies are presented to highlight advances and challenges in various application fields. The first case illustrates how structural health monitoring contributes to a better characterisation of the reliability of the defences and how innovative measures can enhance the reliability. The second case discusses how the river system can be managed in the context of the new safety standards. The third case shows how upgrades and reinforcements of hydraulic structures can be evaluated taking into account (uncertain) future developments, such as sea level rise.