Impact of corporate credit scoring on construction contractors in China

In an attempt to enhance the trustworthiness of contractors and reduce corruption, the China Government has launched a construction contractor credit scoring (CCCS) scheme in Beijing for evaluating the compliance and integrity of contractors registered in the construction market. The contribution of this paper to the Body of Knowledge is to analyze how the incorporation of CCCS may affect general contractors’ present and future competitiveness through a case study in China. The paper analyzes the procurement of 158 building projects tendered in Beijing, involving 2071 local general contractors active in the market. The results show that (1) the contractors’ CCCS scores are important for being awarded large and mega project contracts; (2) CCCS scores have a generally positive effect on future corporate financial income; and (3) that, contrary to expectations, the policy does not increase the CCCS of companies. Finally, it is observed how the changing trend in contractors’ CCCS scores is highly correlated with their initial values (the scores of higher CCCS scoring companies increase faster on average than other companies). Final remarks concern ways to better implement CCCS schemes in the future and avoid the potential risks involved in their use

Enantioselective Fluorescent Recognition of Amino Acids by Amide Formation: An Unusual Concentration Effect

A BINOL-based perfluoroalkyl ketone shows a highly enantioselective fluorescence enhancement in the presence of various amino acid-TBA salts and can be used to determine the enantiomeric composition of these compounds. It was found that the amino acid-TBA salts can act as nucleophiles to cleave the perfluoroalkyl group off of the ketones to form the corresponding amides at room temperature in DMSO. This is the first example of an enantioselective fluorescent sensor for the recognition of amino acids by forming amide bonds under very mild conditions. This study has also revealed an unusual concentration effect leading to an “off-on-off” fluorescence response of the sensor toward one enantiomer of the amino acids

Piezo-phototronic Effect Enhanced Visible and Ultraviolet Photodetection Using a ZnO–CdS Core–Shell Micro/nanowire

The piezo-phototronic effect is about the use of the piezoelectric potential created inside some materials for enhancing the charge carrier generation or separation at the metal–semiconductor contact or <i>pn</i> junction. In this paper, we demonstrate the impact of the piezo-phototronic effect on the photon sensitivity for a ZnO–CdS core–shell micro/nanowire based visible and UV sensor. CdS nanowire arrays were grown on the surface of a ZnO micro/nanowire to form a ZnO–CdS core–shell nanostructure by a facile hydrothermal method. With the two ends of a ZnO–CdS wire bonded on a polymer substrate, a flexible photodetector was fabricated, which is sensitive simultaneously to both green light (548 nm) and UV light (372 nm). Furthermore, the performance of the photon sensor is much enhanced by the strain-induced piezopotential in the ZnO core through modulation of the Schottky barrier heights at the source and drain contacts. This work demonstrates a new application of the piezotronic effect in photon detectors

Endoplasmic Reticulum-Directed Ratiometric Fluorescent Probe for Quantitive Detection of Basal H₂O₂

The endoplasmic reticulum (ER) has a central role in the fine-tuning of environmental and internal stimuli. We herein report a ratiometric fluorescent probe, α-Naph, capable of determining basal H₂O₂ in the ER. The probe specifically responds to H₂O₂. The limit of detection of the probe is as low as 38 nM, making it a feasible sensor to image intracellular basal H₂O₂. In addition, utilizing its ratiometric property, we are able to measure the concentration of H₂O₂ in the ER quantitatively, eliminating the error caused by the probe concentration and environment. The intracellular concentration of H₂O₂ in the ER is calculated to be 0.692 μM under normal conditions and 1.26 μM under the stimulation of phorbol myristate acetate

Regioselective Acetylation of Diols and Polyols by Acetate Catalysis: Mechanism and Application

We propose a principle for H-bonding activation in acylation of hydroxyl groups, where the acylation is activated by the formation of hydrogen bonds between hydroxyl groups and anions. With the guidance of this principle, we demonstrate a method for the selective acylation of carbohydrates. By this method, diols and polyols are regioselectively acetylated in high yields under mild conditions using catalytic amounts of acetate. In comparison to other methods involving reagents such as organotin, organoboron, organosilicon, organobase, and metal salts, this method is more environmentally friendly, convenient, and efficient and is also associated with higher regioselectivity. We have performed a thorough quantum chemical study to decipher the mechanism, which suggests that acetate first forms a dual H-bond complex with a diol, which enables subsequent monoacylation by acetic anhydride under mild conditions. The regioselectivity appears to originate from the inherent structure of the diols and polyols and their specific interactions with the coordinating acetate catalyst

Reversible and Dynamic Fluorescence Imaging of Cellular Redox Self-Regulation Using Fast-Responsive Near-Infrared Ge-Pyronines

Cellular self-regulation of reactive oxygen species (ROS) stress via glutathione (GSH) antioxidant repair plays a crucial role in maintaining redox balance, which affects various physiological and pathological pathways. In this work, we developed a simple yet effective strategy for reversible, dynamic, and real-time fluorescence imaging of ROS stress and GSH repair, based on novel Ge-pyronine dyes (GePs). Unlike the current O-pyronine (OP) dye, the fluorescence of GePs can be quenched in GSH reduction and then greatly restored by ROS (e.g., ClO^–, ONOO^–, and HO^•) oxidation because of their unique affinity toward thiols. The “on–off” and “off–on” fluorescence switch can complete in 10 and 20 s, respectively, and exhibit excellent reversibility in vitro and in cells. GePs also show excitation in the long wavelength from the deep-red to near-infrared (NIR) (621–662 nm) region, high fluorescence quantum yield (Φ_fl = 0.32–0.44) in aqueous media, and excellent cell permeability. Our results demonstrated that GePs can be used for real-time monitoring of the reversible and dynamic interconversion between ROS oxidation and GSH reduction in living cells. GePs might be a useful tool for investigating various redox-related physiological and pathological pathways

H‑Bonding Activation in Highly Regioselective Acetylation of Diols

H-bonding activation in the regioselective acetylation of vicinal and 1,3-diols is presented. Herein, the acetylation of the hydroxyl group with acetic anhydride can be activated by the formation of H-bonds between the hydroxyl group and anions. The reaction exhibits high regioselectivity when a catalytic amount of tetrabutylammonium acetate is employed. Mechanistic studies indicated that acetate anion forms dual H-bonding complexes with the diol, which facilitates the subsequent regioselective monoacetylation

Refine and Strengthen SAR-Based Read-Across by Considering Bioactivation and Modes of Action

Structure–activity relationship (SAR)-based read-across is an important and effective method to establish the safety of a data-poor target chemical (structure of interest (SOI)) using hazard data from structurally similar source chemicals (analogues). Many methods use quantitative similarity scores to evaluate the structural similarity for searching and selecting analogues as well as for evaluating analogue suitability. However, studies suggest that read-across based purely on structural similarity cannot accurately predict the toxicity of an SOI. As mechanistic data become available, we gain a greater understanding of the mode of action (MOA), the relationship between structures and metabolism/bioactivation pathways, and the existence of “activity cliffs” in chemical chain length, which can improve the analogue rating process. For this purpose, the current work identifies a series of classes of chemicals where a small change at a key position can result in a significant change in metabolism and bioactivation pathways and may eventually result in significant changes in chemical toxicity that have a big impact on the suitability of analogues for read-across. Additionally, a series of SAR-based read-across case studies are presented, which cover a variety of chemical classes that commonly link to different toxic endpoints. The case study results indicate that SAR-based read-across can be refined and strengthened by considering MOAs or proposed reactive metabolite formation pathways, which can improve the overall accuracy, consistency, transparency, and confidence in evaluating analogue suitability

Piezo-phototronic Effect Enhanced Visible/UV Photodetector of a Carbon-Fiber/ZnO-CdS Double-Shell Microwire

A branched ZnO-CdS double-shell NW array on the surface of a carbon fiber (CF/ZnO-CdS) was successfully synthesized <i>via</i> a facile two-step hydrothermal method. Based on a single CF/ZnO-CdS wire on a polymer substrate, a flexible photodetector was fabricated, which exhibited ultrahigh photon responsivity under illuminations of blue light (1.11 × 10⁵ A/W, 8.99 × 10^–8 W/cm², 480 nm), green light (3.83 × 10⁴ A/W, 4.48 × 10^–8 W/cm², 548 nm), and UV light (1.94 × 10⁵ A/W, 1.59 × 10^–8 W/cm², 372 nm), respectively. The responsivity of this broadband photon sensor was enhanced further by as much as 60% when the device was subjected to a −0.38% compressive strain. This is because the strain induced a piezopotential in ZnO, which tunes the barrier height at the ZnO–CdS heterojunction interface, leading to an optimized optoelectronic performance. This work demonstrates a promising application of piezo-phototronic effect in nanoheterojunction array based photon detectors

Refine and Strengthen SAR-Based Read-Across by Considering Bioactivation and Modes of Action

Structure–activity relationship (SAR)-based read-across is an important and effective method to establish the safety of a data-poor target chemical (structure of interest (SOI)) using hazard data from structurally similar source chemicals (analogues). Many methods use quantitative similarity scores to evaluate the structural similarity for searching and selecting analogues as well as for evaluating analogue suitability. However, studies suggest that read-across based purely on structural similarity cannot accurately predict the toxicity of an SOI. As mechanistic data become available, we gain a greater understanding of the mode of action (MOA), the relationship between structures and metabolism/bioactivation pathways, and the existence of “activity cliffs” in chemical chain length, which can improve the analogue rating process. For this purpose, the current work identifies a series of classes of chemicals where a small change at a key position can result in a significant change in metabolism and bioactivation pathways and may eventually result in significant changes in chemical toxicity that have a big impact on the suitability of analogues for read-across. Additionally, a series of SAR-based read-across case studies are presented, which cover a variety of chemical classes that commonly link to different toxic endpoints. The case study results indicate that SAR-based read-across can be refined and strengthened by considering MOAs or proposed reactive metabolite formation pathways, which can improve the overall accuracy, consistency, transparency, and confidence in evaluating analogue suitability