Notice of RetractionCountermeasures of Payment Risk in Construction Contract
The contractor lacks of identification ability of risks in construction contracts, which result in loopholes and risks that could be avoid in the signing and implementation process of the instruction contract. Due to lack of identification and prevention of these risks, lead to the losses of the contractors in the project construction courses. To the contractor, the significant risk is the owner's payment risks. It is a universal phenomenon there exist plenty of owners in arrears with project payment or repudiate payment, which result not only from insufficient management of contractors, but also closely related to the credit of owners. This paper firstly elaborate contract management of construction project, and then analyze the risk of construction contract and put emphasize on employer payment risk. Finally, point out that employer payment bond is an effective method of risk transferring in preventing employer arrear, to ensure the profitability and construction can be carried through smoothly.
Surety Bonds for Construction Contracts
This book presents the complex field of suretyship for construction contracts by describing and analyzing each element of the surety bonding process in basic terms. Russell unravels the suretyship puzzle through numerous examples and extended case studies drawn from real-world experience. Sample bond forms and surety documents, as well as an extensive glossary of key terms, serve to further illustrate each step of the bonding process.
An Ultrasensitive Analytical Method Based on Chemiluminescence Sensing Electrochemical Parallel Catalytic Reaction Event
An ultrasensitive electrochemiluminescence (ECL) method on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed for improving ECL analytical characteristics using vanadate(V) as a representative. Vanadate(V) could be electrochemically reduced to generate vanadate(II) which could be chemically oxidized by potassium periodate to regenerate vanadate(V) and give parallel catalytic wave effect. Then, the reduced product of potassium periodate could react with butyl-rhodamine B to emit a sensitive chemiluminescence signal. The chemiluminescence intensity was correlative with vanadate(V) concentration. The investigation on the electrochemical reaction rate constant (k0) confirmed that the speed of electrochemical reaction was faster than that of the subsequent chemiluminescence reaction. The possibility of the combination of electrochemical parallel catalytic reaction with chemiluminescence signal sensing was proved. The similar ECL behaviors could be observed at zirconia nanowires-Nafion modified electrode. Because of the separation and enrichment effect of the modified electrode on vanadate(V), the selectivity and sensitivity was further improved greatly. Based on these findings, a new concept on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed and an ultrasensitive ECL method for the determination of vanadate(V) was developed at zirconia nanowires-Nafion modified electrode. Under the optimum experimental conditions, the ECL intensity was linear with the concentration of vanadate(V) in the range of 2.0×10−12 mol/L–2.0×10−10 mol/L. The detection limit was 8.0×10−13 mol/L, which was more than 6 orders of magnitude lower than that observed by electrochemical current transduction for electrochemical parallel catalytic reaction at zirconia nanowires-Nafion modified electrode.