[Developmental characteristics of biological soil crusts and their effects on soil water infiltration on karst slope]. / å–€æ–¯ç‰¹å¡é¢ç”Ÿç‰©ç»“çš®å‘è‚²ç‰¹å¾åŠå ¶å¯¹åœŸå£¤æ°´åˆ†å ¥æ¸—çš„å½±å“.

Biological soil crusts (BSCs), as a pioneer for vegetation restoration and crucial component of surface landscape, greatly affect land surface process. To explore the development of BSCs and its effects on soil water infiltration in karst region, we investigated the development of BSCs and analyzed the infiltration processes with different BSCs coverages (0, 28%, 40%, 70%, 97%) and rainfall intensities (42 and 132 mm·h-1) in simulating rainfall experiments on a typical karst slope. The results showed that there were significant differences in the development of BSCs for different land use types, whereas the spatial variation of BSCs development on the slope was not obvious under the same land use type. Compared to the bare plot, the presence of BSCs significantly increased surface roughness, the initial runoff generation time, and soil water infiltration. In the cases of light (42 mm·h-1) and intensive (132 mm·h-1) rainfall, the initial infiltration rate of BSCs covered plots were 1.7-1.9 times and 1.2-1.9 times as that of bare plot, while the average infiltration rate in BSCs covered plots were 2.5-3.0 times and 1.4-3.3 times as that of bare plot, respectively. The BSCs coverage was significantly positively correlated with the initial runoff production time. The critical values of facilitating infiltration of BSCs coverage were between 65% and 70% under the test rainfall intensities. For heavy rainfall events, the inhibiting effects of BSCs on surface runoff were weakened. Horton model was the most reliable one for describing the infiltration process on karst slope with BSCs, followed by Kostiakov model and Philip model. In conclusion, the spatial variability of BSCs development on the karst slope was higher. The presence of BSCs had a significant effect on soil permeability in karst region.

[Effects of no-tillage on soil water content and physical properties of spring corn fields in semiarid region of northern China].

Field experiments were conducted in 2006-2008 to study the effects of no-tillage on the spatiotemporal dynamics of soil water content and related soil physical properties in spring corn fields in Beijing region during growth season. In study period, the water storage in 0-100 cm soil layer in tillage and no-tillage treatments had the same variation trend with time and precipitation, but the water storage at different time periods and under different precipitations was 2.7%-30.3% higher in no-tillage treatment than in tillage treatment. When the precipitation was relatively abundant, the increment of soil water storage was somewhat increased, but no-tillage was still worth to be popularized in the regions relatively deficit in precipitation. Under no-tillage, the average water storage in 0-100 cm soil layer during the three growth seasons in 2006-2008 was 3.4%-12.8% higher than that under conventional tillage, and the increment of the water storage in 0-20 cm and 80-100 cm soil layers under no-tillage was higher than that in intermediate layer, with the highest increment reached 22.2%. No-tillage improved soil water-holding capacity and water use efficiency via decreasing soil bulk density, increasing soil porosity, and promoting the formation of soil water-stable aggregates, and thereby, promoted crop yielding. After 3 years no-tillage, the soil water use efficiency and spring corn yield were increased by 13.3% and 16.4%, respectively, compared with those under conventional tillage.

Links between environmental geochemistry and rate of birth defects: Shanxi Province, China.

The rate of birth defects in Shanxi Province is among the highest worldwide. In order to identify the impacts of geochemical and environmental factors on birth defect risk, samples of soil, water and food were collected from an area with an unusually high rate of birth defects (study area) and an area with a low rate of birth defects (control area) in Shanxi Province, China. Element contents were determined by ICP-OES, and the results were analyzed using a non-parametric test and stepwise regression. Differences in the level and distribution of 14 geochemical elements, namely arsenic (As), selenium (Se), molybdenum (Mo), zinc (Zn), strontium (Sr), iron (Fe), tin (Sn), magnesium (Mg), vanadium (V), calcium (Ca), copper (Cu), aluminum (Al), potassium (K) and sulfur (S) were thus compared between the study and control areas. The results reveal that the geochemical element contents in soil, water and food show a significant difference between the study area and control area, and suggest that the study area was characterized by higher S and lower Sr and Al contents. These findings, based on statistical analysis, may be useful in directing further epidemiological investigations identifying the leading causes of birth defects.

Glucocorticoids aggravate retrograde memory deficiency associated with traumatic brain injury in rats.

Administration of glucocorticoid to patients with head injury has previously been demonstrated to impair memory. We hypothesize that glucocorticoids promote post-traumatic hippocampal apoptosis, resulting in retrograde memory deficiency associated with traumatic brain injury (TBI). In the present study, we tested this hypothesis by measuring spatial memory deficiency in rats subjected to fluid percussion injury (FPI) and receiving dexamethasone (DXM at 0.5-10 mg/kg) or methylprednisolone (MP at 5-30 mg/kg); we also examined neuronal apoptosis in hippocampus. Adult male Wistar rats were trained for the acquisition of spatial memory, then subjected to FPI and tested for spatial reference memory on post-injury days 7 and 14 using the Morris Water Maze. Brain tissue from injured rats was examined 24 h to 2 weeks after injury. The percent time in the goal quadrant, which measures spatial reference memory, was significantly lower in injured rats receiving either high-dose DXM or MP than in control groups. TUNEL-positive cells in hippocampus were first detected 24 h post-injury, plateauing at 48h. The number of TUNEL-positive cells was significantly higher in injured rats treated with either DXM or MP. The data suggest that glucocorticoid therapy for TBI may increase neuronal apoptosis in hippocampus and, as a result, aggravate retrograde memory deficits induced by TBI.

Cellular internalization and in vivo tracking of thermosensitive luminescent micelles based on luminescent lanthanide chelate.

An amphiphilic tris(dibenzoylmethanato)europium(III) (Eu(DBM)(3)) coordinated P(MMA-co-EIPPMMA)-co-P(NIPAAm-co-NDAPM) copolymer was synthesized, which exhibited good biocompatibility and emitted strong red luminescence (MMA, methyl methacrylate; EIPPMMA, 4-(1-ethyl-1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)phenyl methacrylate; NIPAAm, N-isopropylacrylamide; NDAPM, (N-(3-dimethylamino)propyl)methacrylamide). The copolymer could self-assemble into micelles of size around 260 nm, and the micelles were thermosensitive at around body temperature. The drug-loaded micelles showed thermosensitive controlled drug release, and the paclitaxel loaded micelles were capable of being internalized into the tumor cells (A549) and exhibited obvious inhibition to the growth of A549 cells. Importantly, in vivo study showed the self-assembled micelles of Eu(DBM)(3) coordinated P(MMA-co-EIPPMMA)-co-P(NIPAAm-co-NDAPM) copolymer uptaken by the larvae of zebrafish could be easily tracked and be eliminated from the body within several days.

[Rheological phase synthesis and characterization of lanthanum salicylate and luminescence properties of Tb3+ -doped lanthanum salicylate].

Lanthanum salicylate and Tb3+ -doped lanthanum salicylate were synthesized with the rheological phase reaction method. Elemental analysis, IR, TG, DTA and powder X-ray diffraction were investigated to determine the composition, crystal structure and coordination manner between the COO- and ion La3+ of lanthanum salicylate. The emission and excitation spectra of Tb3+ -doped lanthanum salicylate were also discussed. Powder X-ray diffraction suggests that the compound has a layered monoclinic structure, and the lattice parameters are a = 21.6010 A, b = 13.8015 A , c = 3.8103 A, beta = 97.11 degrees, V = 1127.2 A3, Z = 2, rhocal = 1.621 g x cm(-3) and rhoexp = 1.653 g x cm(-3). The Tb3+ -doped lanthanum salicylate exhibits very strong green luminescence of Tb3+ under the excitation of UV light. And the transition from 5D4 to 7F5 is the strongest one.

[Research on IR spectra of Li-Mn spinel].

The infrared spectra of Li-Mn-spinel were studied in this paper. As the structure of Li-Mn-spinel was classified as Fd3m space group, the lithium ions (Li(I)) occupy tetrahedral sites (8a sites) and manganese ions (Mn(IV) or Mn(III)) occupy octahedral sites (16d sites). The internal relationship between vibration modes and infrared activity was discussed based on the knowledge of group theory. The experimental IR spectra of Li-Mn-spinel were presented also. By theoretical analysis, we concluded that the bands at 618.6 and 501.5 cm-1 resulted from anti-symmetric stretching vibration of Mn(IV)-O and Mn (III)-O in Li-Mn-spinel crystal (Mn(IV)O6 and Mn(III)O6 octahedron), respectively, the weak band at 1,124 cm-1 resulted from anti-symmetric stretching vibration of Li-O in the spinel (LiO4 tetrahedron), and other possible bands at wave number lower than 400 cm-1 were not detected in the range from 400 to 4,000 cm-1. The reliability of conclusions was proved by IR spectra of both the Li-Mn-spinel and doped Li-Mn-spinel.