Study on Subjective Evaluation of Acoustic Environment in Urban Open Space Based on "Effective Characteristics".

With the continuous expansion of urban scale with dense population and traffic and the gradual improvement of residents' requirements for environmental quality, the traditional evaluation method relying on acoustic energy is not enough to reflect the feelings of urban crowds about acoustic environment quality. The acoustic environment quality evaluation method based on human subjective perception has gradually become one of the research focuses in the field of environmental noise control. In recent years, various subjective and objective acoustic characteristic parameters have been introduced into the study of acoustic environment assessment in the global literature. However, the extraction of "effective characteristics" from a large number of physical and psychoacoustic characteristics contained in acoustic signals and the creation of a scientific and efficient subjective evaluation model have always been key technical problems in the field of acoustic environment evaluation. Based on subjective human perceptions, the overall acoustic environment quality evaluation of urban open spaces is studied in this paper. Based on the "effective characteristic" parameters and the subjective characteristic proposed in the previous research, including equivalent continuous A-weighted sound pressure level (LA), the difference between median noise and ambient background noise (L50 - L90), Sharpness (Sh), as well as satisfaction (Sat), the multivariable linear regression algorithm is used to further study the intrinsic correlation between the proposed "effective characteristics" and subjective perception. Then, a satisfaction evaluation model of the acoustic environment based on "effective characteristics" is built in this paper. Furthermore, the soundwalk evaluation experiment and the MATLAB numerical simulation experiment are carried out, which verify that the prediction accuracy of the proposed model is more than 92%, the consistency of satisfaction level is more than 88%, as well as the changes in the values of Sh and L50 - L90 have a significant impact on the satisfaction prediction of the proposed model. It shows that the proposed "effective characteristics" more comprehensively describe the quality level of the regional acoustic environment in urban open space compared with a single LA index, and the proposed acoustic environment satisfaction evaluation model based on "effective characteristics" has significant accuracy superiority and regional applicability.

[Simultaneously determination of atropine sulphate, diphenhydramine hydrochloride, capsaicin and dihydrocapsaicin in pain-relieving plaster for arthritis by RP-HPLC].

OBJECTIVE: To establish RP-HPLC method for determination of atropine sulphate, diphenhydramine hydrochloride, capsaicin and dihydrocapsaicin in pain-relieving plaster for arthritis. METHOD: The sample were separated on an Alltima C18 Column (4.6 mm x 250 mm, 5 microm) with the moblie phase of CH3 CN-0.1% H3 PO4. Flow rate was 1 mL x min(-1). The detective wavelength was set at 210 and 280 nm. Column temperature was 30 degrees C. RESULT: The calibration curve for atropine sulphate, diphenhydramine hydrochloride, capsaicin and dihydrocapsaicin revealed linearity in the range of 2.01-50.25, 15.08-377.00, 5.02-125.50, 5.03-125.75 mg x L(-1), respectively. The recoveries of atropine sulphate, diphenhydramine hydrochloride, capsaicin and dihydrocapsaicin were 99.00% with RSD of 0.95%, 99.89% with RSD of 1.2%, 100.1% with RSD of 1.5% and 99.51%, with RSD of 1.4%, respectively. CONCLUSION: The method is simple, rapid and accurate, which is suitable for the quality control of pain-relieving plaster for arthritis.

Lifetime of ligand-receptor clusters under external force.

We present a theory for the lifetime T(N,f) of a ligand-receptor cluster with N bonds under constant external force F=fN , where f is force per bond. We show that there exists a critical force per bond f(c) such that at large N when f>f(c) the lifetime T(N,f) is independent of cluster size N ; when f>f(c) the lifetime scales as ln[T(N,f)] approximately N due to a free energy barrier with height approximately N along the dissociation path; when f=f(c), the lifetime scales as T(N,f) approximately N(1/3) due to strong fluctuation of a number of closed bonds. Our study shows that adhesion clusters with more bonds are more stable at small f but respond to external force as fast as smaller adhesion clusters at large f .

Theoretical determination of the strength of soft noncovalent molecular bonds.

The strength of a simple soft bond under a constant loading rate is studied theoretically. There is a scaling regime where rebinding is negligible and the rupture force scales as const+ [ln (kv) ](2/3) , where kv is the loading rate. The scaling regime is smaller for weaker bonds and broader for stronger bonds. For a loading rate beyond the upper limit of the scaling regime, the bond rupture is deterministic and the thermal effects are negligible. For a loading rate below the lower limit of the scaling regime, the contribution from rebinding becomes important and there is no simple scaling relation between the rupture force and the loading rate. Our theory takes the effect of rebinding in the calculation, therefore we find good agreement between theory and simulation even below the scaling regime.