Effect of sulfur source on photocatalytic degradation performance of CdS/MoS2 prepared with one-step hydrothermal synthesis

Cd S/Mo S2,an extremely efficient photocatalyst,has been extensively used in hydrogen photoproduction and pollutant degradation.Cd S/Mo S2can be synthesized by a facile one-step hydrothermal process.However,the effect of the sulfur source on the synthesis of Cd S/Mo S2via one-step hydrothermal methods has seldom been investigated.We report herein a series of one-step hydrothermal preparations of Cd S/Mo S2using three different sulfur sources：thioacetamide,L-cysteine,and thiourea.The results revealed that the sulfur source strongly affected the crystallization,morphology,elemental composition and ultraviolet（UV）–visible-light-absorption ability of the Cd S/Mo S2.Among the investigated sulfur sources,thioacetamide provided the highest visible-light absorption ability for Cd S/Mo S2,with the smallest average particle size and largest surface area,resulting in the highest efficiency in Methylene Blue（MB）degradation.The photocatalytic activity of Cd S/Mo S2synthesized from the three sulfur sources can be arranged in the following order：thioacetamideL-cysteinethiourea.The reaction rate constants（k）for thioacetamide,L-cysteine,and thiourea were estimated to be 0.0197,0.0140,and 0.0084 min^（-1）,respectively.However,thioacetamide may be limited in practical application in terms of its price and toxicity,while L-cysteine is relatively economical,less toxic and exhibited good photocatalytic degradation performance toward MB.

Geological features and S isotope composition of tin deposit in Dachang ore district in Guangxi

The geological investigation of the Dachang ore field was carried out in detail, and the geological characteristics of the deposits, consisting of the Tongkeng and Dafulou deposits, were observed and researched systematically. It suggests that the mineralization types of Changpo ore are composed of cracking vein, thin vein, bedded vein and thin vein-net vein disseminated types. The cracking vein ore is usually lens-shaped in the vertical direction. The thin vein ore is always characterized by a stable trend and tendency. The bedded ore always occurs along the strata in the way of filling and metasomatism in the fracture system. In terms of Bali-longtoushan ore, it is characterized by complicated mineral components and a variety of minerals. More generally, ore textures consist of the anhedral-subhedral shapes and thin particle, and secondary with the interstitial texture, solid solution separation texture, dissolution texture, corona texture, and crushing texture, yet ore structures include the massive, veinlet, disseminated, banded, miarolitic, biological residual and brecciated structure. In addition, the sulfur isotopes of the metal sulfide were analyzed. The results show that the δ34S values of Tongkeng ore range from-0.30% to 1.38% with more dispersed characteristics, yet in terms of Dafulou ore, the δ34S values are from-0.15% to 0.22% which are characterized by more focused. This indicates that the sulfur isotope composition has large difference between the different deposits. The sulfur isotope values of the Dafulou ore are concentrated relatively, yet are dispersed for the Tongkeng ore. Likewise, there are also divergences of sulfur isotopes for the different minerals. The sulfur isotope values of pyrrhotine are dispersed, yet are homogeneous for pyrite. In short, the divergence of the sulfur isotope is reflected in both the different deposits and minerals, all of these may account for the difference of sulfur sources.

Phytophthora Root and Crown Rot on Fruit Trees in Bulgaria

Phytophthora root and crown rot was found on the fruit trees in Bulgaria for the first time in the period 1998-1999. Monitoring of the disease spread from 2000 to 2007 points out incidence between 2 and 14 per cent, in some orchards and nurseries in the Southern part of Bulgaria. The following Phytophthora species were identified based on morphological and cultural characteristics, and temperature requirements： Phytophthora cactorum, Phytophthora citrophthora, Phytophthora drechsleri, Phytophthora cryptogea, Phytophthora hybrid specie and Pythium. Prevailing specie was P. cactorum. P. cryptogea and P. cactorum were confirmed by application of molecular methods. Nutritional requirements of P. cactorum and P. citrophthora were studied. Most Nitrogen sources stimulated the mycelial growth of P. cactorum to a higher extend, and reduced the colony size ofP. citrophthora. Different Carbon sources were utilized well by P. cactorum, and only saccharose and maltose had a stimulating effect on the mycelial growth of P. citrophthora. MgSO4.7H20 was the preferred sulfur source for both fungi, as L-cysteine and L-methionine only for P. cactorum. Phytophthora infection leads to physiological changes in the.host plant tissues. The tendency traced out is： about disorders in the amino acid metabolism, increase in the total sugars and slight reduction of the cellulose content. The total nitrogen, phosphorus and potassium content are reduced and the calcium and magnesium are increased. Photosynthesis of inoculated plants was suppressed and transpiration was increased.

Origin of high particle number concentrations reaching the St. Louis, Midwest Supersite

Ultrafine particles are associated with adverse health effects. Total Particle Number Concentration（TNC） of fine particles were measured during 2002 at the St. Louis — Midwest supersite. The time series showed overall low level with frequent large peaks. The time series was analyzed alongside criteria pollutant measurements and meteorological observations. Multiple regression analysis was used to identify further contributing factors and to determine the association of different pollutants with TNC levels. This showed the strong contribution of sulfur dioxide（SO2） and nitrogen oxides（NO x） to high TNC levels. The analysis also suggested that increased dispersion resulting from faster winds and higher mixing heights led to higher TNC levels. Overall, the results show that there were intense particle nucleation events in a SO2 rich plume reaching the site which contributed around 29% of TNC. A further 40% was associated with primary emissions from mobile sources. By separating the remaining TNC by time of day and clear sky conditions,we suggest that most likely 8% of TNC are due to regional nucleation events and 23% are associated with the general urban background.