Fluorescent carbon quantum dots-based prodrug nanosponges with outstanding tumor-specific drug delivery and imaging

Carbon quantum dots (CQD)-based nanosponges have been widely designed for tumor theranostic application recently. However, the drug content is usually lower with the shorter dynamic covalent linkers while the longer hydrophilic dynamic covalent linkers led to a significant premature drug leakage. Here, a hydrophobic linear reducible-responsive linker with two terminal aldehyde group was designed to crosslink the hydrazine-functionalized PEGylated CQDs (Hy-CQD-PEG), resulting in Hy-CQDss-PEG nanosponges. After doxorubicin (DOX) conjugation, the DOX-Hy-CQDss-PEG prodrug nanosponges were obtained with DOX content of 18.76 % and hydrodynamic diameter of 140 nm, respectively. The DOX-Hy-CQDss-PEG nanosponges were stable in the normal physiological medium with very low drug leakage and fluorescence, while they could disintegrate in the tumor intracellular microenvironment, releasing DOX and the hydrazine-functionalized CQDs for theranostic application.     

Acid–base transport model depicting the dynamic pH response of interfacial reactions

Acid–base transport is integral to many important interfacial reactions in various fields of chemistry, but its theoretical foundation is lacked. Herein, a common acid–base transport model is established owing to the success in deriving buffer transport equations. This model is applicable to most buffer systems by flexibly integrating the transport equations in terms of buffer components, and is verified through the model relationships of buffer transport limiting current by using hydrogen evolution reaction experiments. Based on model calculations, two diagram approaches are proposed to depict the dynamic pH response and aid buffer operation optimizations. The model and methods allow us to quantify the rate-limiting effect of acid–base transport on interfacial reactions and to precisely control the effect through medium regulations. Furthermore, the model has laid the foundation of dynamic pH effect on species transformation and process mechanism, which can be of wide interest in the chemistry encompassing interfacial reactions.     

Mechanisms of molecular and structural interactions between lentil and quinoa proteins in aqueous solutions induced by pH recycling

There has been a growing interest in plant proteins due to their beneficial health effects, low cost and variety of applications in food industries. The low solubility of lentil proteins (LPs) is one of the significant factors that limit their use in food applications. Quinoa proteins (QPs), which have high water solubility, were combined with LPs at pH 12 to generate LP-QP complexes to generate pH-based soluble protein compounds. The LP-QP complexes demonstrated a large surface charge with an increase solubilisation of the protein complexes by more than 85%, together with resistance to protein aggregation. The combination of LPs to QPs led to a significant increase (P < 0.05) in unique tertiary and secondary protein structures as determined by the protein–protein interaction (PPI) technique involving pH recycling. Interactions between LPs and QPs affected the surface morphology of the protein complexes formed. Electrostatic interactions, hydrophobic forces and hydrogen bonding were indicated to play key roles in the PPIs. The capacity of pH cycling to illustrate the above protein interactions shows that this is a robust approach for assessing the emulsion and foaming properties of food proteins.     

硅灰石的化学镀镍及其导电性能

采用化学镀方法制备镀镍针状硅灰石粉,以SEM表征镀镍粉的形貌,XRD表征其结构,柱塞式装置评价其导电性。结果表明:当盐酸溶液pH值大于1.5时与硅灰石反应8min,酸性溶液对硅灰石表面的侵蚀不明显。化学镀镍过程中,硅灰石分别经pH值为3.0的敏化液和活化液处理3min和5min,镀镍硅灰石保持原有的针状结构,表层包覆镍磷合金,具有良好的导电性。     

云浮硫铁矿炸药自爆问题的研究与预防

本文在探讨硫化矿炸药自爆原因基础上,提出了简单、实用的炸药自爆矿样的检测方法和防自爆措施,可供类似矿山鉴用。     

东鞍山难选铁矿石浮选与矿浆pH值,电位的关系

采用Ｎａ２ＣＯ３为调整剂，用氧化还原剂调控电位，研究了矿浆ｐＨ值及矿浆电位对东鞍山碳酸铁型难选矿、高亚铁型难选矿和现场生产矿样浮选行为的影响。     

Harmful effects of un-ionised ammonia on the zooplankton community in a deep waste treatment pond

The harmful effects of NH(3) on the zooplankton community in a deep waste treatment pond were evaluated under natural conditions. The pond, supplied with secondary effluent from a conventional urban wastewater treatment plant, was designed to improve water quality for agricultural reuse.The aim of the study was to verify the hypothesis suggested in Arauzo et al. (Water Environ. Res. 34(14), 3666) that during phytoplankton blooms in the stratification periods high un-ionised ammonia content values, due to an intense photosynthetic activity and high related pH, lead to a decrease in zooplankton biomass and, thus, to a collapse of the treatment process efficiency.Empirical models were developed to determine relationships between phytoplankton biomass, pH and NH(3) levels. They provided an easy and quick method of detecting when the system was liable to collapse due to the NH(3) effect on the zooplankton community and offered the possibility of adopting measures to guarantee water quality at the effluent. A significant decrease in zooplankton community biomass was observed at un-ionised ammonia levels over 2.5 mgL(-1).     

The effect of pH on the competition between polyphosphate-accumulating organisms and glycogen-accumulating organisms

In enhanced biological phosphorus removal (EBPR) processes, glycogen-accumulating organisms (GAOs) may compete with polyphosphate-accumulating organisms (PAOs) for the often-limited carbon substrates, potentially resulting in disturbances to phosphorus removal. A detailed investigation of the effect of pH on the competition between PAOs and GAOs is reported in this study. The results show that a high external pH ( approximately 8) provided PAOs with an advantage over GAOs in EBPR systems. The phosphorus removal performance improved due to a population shift favouring PAOs over GAOs, which was shown through both chemical and microbiological methods. Two lab-scale reactors fed with propionate as the carbon source were subjected to an increase in pH from 7 to 8. The phosphorus removal and PAO population (as measured by quantitative fluorescence in situ hybridisation analysis of "Candidatus Accumulibacter phosphatis") increased in each system, where the PAOs appeared to out-compete a group of Alphaproteobacteria GAOs. A considerable improvement in the P removal was also observed in an acetate fed reactor, where the GAO population (primarily "Candidatus Competibacter phosphatis") decreased substantially after a similar increase in the pH. The results from this study suggest that pH could be used as a control parameter to reduce the undesirable proliferation of GAOs and improve phosphorus removal in EBPR systems.     

Ecological equilibrium on biological activated carbon

This paper examines the potential of a biological activity control system (BACS) for biological activated carbon (BAC) in comparison to granular activated carbon (GAC) for the treatment of potable water. The overall objective of the project is to produce drinking water of a higher quality more economically by developing a BACS for exhausted GAC that can be transformed to BAC by the development of a natural biofilm during the bio-regeneration mode. The research therefore may be interesting for water companies and the activated carbon industry. Findings show that the lifetime of a GAC filter can be significantly extended by maintaining an active biofilm that has to be controlled in order to avoid filter clogging. The most important parameters are dissolved oxygen (DO), pH and a correct balance of nutrients, which enables a natural control of the biomass. pH control was required to maintain an optimal bacteria-protozoa level. Excessive growth of filamentous bacteria can be prevented by a decrease in DO, increase in pH and the reduction of one essential nutrient, e.g. total phosphorus (P). Total organic carbon (TOC) and chemical oxygen demand (COD) values were reduced by bioactivity. DO, turbidity and suspended solids (SS) values were kept in acceptable ranges with respect to drinking water objectives. Plants without a significant population of protozoa deliver turbid low quality effluent high on SS and biochemical oxygen demand (BOD). It was possible to control the biofilm on GAC containing a natural biofilm and BAC during the bio-regeneration mode. Natural and artificial bio-regeneration lead to similar performance characteristics.     

A Study into the Cause of Decline in pH During Water Distribution

T his STUDY INVESTIGATES the decline in pH of soft waters during distribution. The fieldwork and laboratory data confirmed and quantified the pH decline in soft water that had had the pH increased by lime addition at the treatment stage. A pH of 9.0 can decline to 7.5 during distribution. The role of humic acid as a causative agent of pH decline is examined in detail by modified jar test experiments and the development of a dialysis technique. The results of these experiments show that binding or complexing occurs between the humic acid and the calcium ions. This complexing generates H⁺ ions with the consequential decline in pH of the water.