Predicting the Time-Dependent Toxicities of Binary Mixtures of Five Antibiotics to Vibrio qinghaiensis sp.-Q67 Based on the QSAR Model

Antibiotics may be exposed in a mixed state in natural environments.The toxicity of antibiotic mixtures exhibits time-dependent characteristics,and data on the time-dependent toxicity of antibiotic mixtures is also relatively lacking.In this study,the toxicities of 45 binary mixtures composed of five antibiotics were investigated against Vibrio qinghaiensis sp.-Q67(Q67)at multiple exposure times(4,6,8,10,and 12 h).Quantitative structure–activity relationship(QSAR)models were developed for predicting the time-dependent toxicities of 45 binary mixtures.The results showed that the best QSAR models presented coefficient of determination(R2)of(0.818–0.913)and explained variance in prediction leave-one-out(Q2LOO)of(0.781–0.894)and predictive ability(Q2F1,Q2F2,Q2F3>0.682,concordance correlation coefficient>0.859).The R2 values of QSAR models outperformed the R2(0.628–0.810)of the conventional concentration addition models and the R2(0.654–0.792)of the independent action models.Furthermore,the QSAR models showed higher R2 and Q2LOO values at 4 h compared to other exposure times.Specifically,the model at the 30%effective concentration(EC30)had R2 of 0.902 and Q2LOO of 0.883,while the model at the 50%effective concentration(EC50)had R2 of 0.913 and Q2LOO of 0.894.The CATS2D_04_DP descriptor was found to be the most dominant and negatively correlated factor influencing the toxicity of mixed antibiotics against Q67 in the nine QSAR models developed over five exposure times.The reduction in the number of DP pharmacophore point pairs with a topological distance of 4 in the represented molecules is the primary cause for the rise in the time-dependent toxicity of the antibiotics against Q67.

Role of Hematite-Rich Host Rocks in the Gold Mineralization of the Woxi Au(-Sb-W) Ore Deposit in Western Jiangnan Orogen of South China

The formation of many hydrothermal gold deposits is closely related to iron-rich rocks. The host rocks of the Madiyi Formation of the Mid-to Late Neoproterozoic Banxi Group for the Woxi Au(-Sb-W) deposit, which is located in western Hunan Province of the western Jiangnan Orogen, South China, is rich in hematite, which provides a good example for studying the relationship between the formation of gold deposit and iron-rich rocks. Field investigation and petrographic observation on the unaltered, weakly altered and strongly altered rocks demonstrate that the bleaching is caused by a combination of carbonatization, sulfidation and sericitization. Mass balance calculation suggests that, during decolourization there is no change in TFe_(2)O_(3), while FeO is gained and Fe_(2)O_(3)is lost. Geochemical modeling found that Au was mainly present as AuHS(aq) and Au(HS)-2, and that the water-rock interactions decreased the sulfur fugacity which destroyed the stability of such aqueous complexes. Combined with the locally occurred native gold in quartz veins, it is concluded that the major gold precipitation mechanisms are sulfidation and fluid boiling. Based on previous geochronological and geochemical research further gold mineralization is proposed to be generated by deep sourced magmatic or metamorphic fluid migrated upward along the Woxi fault, and the iron-rich Madiyi Formation is the idea chemical trap for gold deposition. The decrease of sulfur contents caused by fluid-rock interactions and fluid boiling are the major mechanisms for gold mineralization.

Structural deformation, metallogenic epoch and genetic mechanism of the Woxi Au-Sb-W deposit, Western Hunan Province, South China

The remobilization,migration,precipitation,and enrichment of ore-forming elements are closely related to structures.Therefore,detailed regional and ore-field structural analyses are critical for determining the genesis of a mineral deposit.The Jiangnan Orogenic Belt(JOB)is an important gold polymetallic metallogenic belt in South China,which is characterized by multiple periods of gold mineralization in the Paleozoic and Mesozoic.However,the genesis of these gold polymetallic deposits is still not well understood due to a lack of systematic research on the regional geology,ore-controlling structures and metallogenic mechanism.In this study,a detailed structural survey at the surface and in the subsurface tunnels was conducted on the Woxi Au-Sb-W deposit,the genesis of which is relatively controversial among the gold polymetallic deposits in the JOB due to poor structural constraints.In addition,a wolframite U-Pb dating was carried out to further constrain the relationship between structures and mineralization.Based on the results of these studies,together with those from previous studies,it is proposed that the Woxi deposit and surrounding areas likely underwent six periods of regional deformation,which are constrained in time and geodynamic setting.Furthermore,we present a systematic discussion on the roles of ore-controlling structures in the transportation,distribution,and deposition of ore-forming elements and localization of orebodies.According to the wolframite dating results,structural analyses,and previous data,we propose that the Woxi Au-Sb-W deposit was formed in two stages during the Yanshanian:a W(wolframite)-Au mineralization stage at ca.140 Ma and an Au-Sb-W(scheelite)mineralization stage at<130 Ma.These mineralizing events are interpreted to have a tight relationship with tectonic reactivation,and the ore-forming fluids were derived from deep sources,including those of magmatic or metamorphic origins.The Woxi deposit can therefore be classified as an“intracontinental reactivation-type”,and the mineralization is related to lithospheric extension caused by plate retreat,retention,and delamination following the cessation of westward subduction of the Paleo-Pacific Plate beneath the East Asian continent.

Improved sprinkler irrigation layouts for smallholders

Pressurized irrigation systems are economically justifiable for medium-to large-scale farms,while fewer choices are available for smallholders.The current research work provides additional options for small plots,as the only income source for low-income farmers in poorer countries,which produce a considerable portion of the agricultural products in some regions of the world.In this research,two novel layouts of a semipermanent sprinkler irrigation system,namely,clock hand(CH)and corner pivot(CP)lateral designs,were designed for a lighter irrigation system to lower the cost requirement.The new techniques were based on a quadrant/full circle movement pattern of manually pivoting laterals,with no/shorter main pipe requirements,which causes a higher system efficiency.These retrofitted layouts were examined in different farms with areas of 0.20 hm^(2),0.81 hm^(2),1.62 hm^(2),and 3.24 hm^(2) in Guangxi,China.This study introduced,analyzed,and compared the layouts with the widespread traditional split lateral method on technical planning,components,implementation,operation details,size optimization,performance evaluation,and economic advantages.In comparison with the traditional system,CH and CP were found to be more user-friendly and cost-effective but slightly complicated in design with higher required manual work.The results revealed a distribution uniformity(LQDU)of 81.0%to 84.0%via the catch can method,lower capital costs(35.0%-45.0%),and lower annual expenses(6.5%-9.8%)for CP and CH,respectively,compared to the split lateral method.The 0.81 hm^(2) and 1.62 hm^(2) farms were found to be the optimum farm sizes for implementation of the new methods for a 25-year project time horizon.The outcomes of this experimental work can encourage small farm owners with limited capital to apply pressurized systems for efficient irrigation and water resource sustainability.