Optical-resolution photoacoustic microscopy of ischemic stroke

A major obstacle in understanding the mechanism of ischemic stroke is the lack of a tool to noninvasively or minimally invasively monitor cerebral hemodynamics longitudinally. Here, we applied optical-resolution photoacoustic microscopy (OR-PAM) to longitudinally study ischemic stroke induced brain injury in a mouse model with transient middle cerebral artery occlusion (MCAO). OR-PAM showed that, during MCAO, the average hemoglobin oxygen saturation (sO2) values of feeder arteries and draining veins within the stroke core region dropped ~10% and ~34%, respectively. After reperfusion, arterial sO_2 recovered back to the baseline; however, the venous sO_2 increased above the baseline value by ~7%. Thereafter, venous sO_2 values were close to the arterial sO_2 values, suggesting eventual brain tissue infarction

Optical-resolution photoacoustic microscopy of ischemic stroke

A major obstacle in understanding the mechanism of ischemic stroke is the lack of a tool to noninvasively or minimally invasively monitor cerebral hemodynamics longitudinally. Here, we applied optical-resolution photoacoustic microscopy (OR-PAM) to longitudinally study ischemic stroke induced brain injury in a mouse model with transient middle cerebral artery occlusion (MCAO). OR-PAM showed that, during MCAO, the average hemoglobin oxygen saturation (sO2) values of feeder arteries and draining veins within the stroke core region dropped ~10% and ~34%, respectively. After reperfusion, arterial sO_2 recovered back to the baseline; however, the venous sO_2 increased above the baseline value by ~7%. Thereafter, venous sO_2 values were close to the arterial sO_2 values, suggesting eventual brain tissue infarction

Rapid biotic rebound during the late Griesbachian indicates heterogeneous recovery patterns after the Permian-Triassic mass extinction

New fossil data from two Early Triassic (Griesbachian to Dienerian) sections from South China show unusually high levels of both benthic and nektonic taxonomic richness occurring in the late Griesbachian. In total, 68 species (including 26 newly originated species) representing mollusks, brachiopods, foraminifers, conodonts, ostracods, and echinoderms occur in the late Griesbachian, indicating well-established and relatively complex marine communities. Furthermore, the nekton shows higher origination rates than the benthos. Analyses of the sedimentary facies and size distribution of pyrite framboids show that this high-diversity interval is associated with well-oxygenated environments. In contrast to the previously suggested scenario, which inferred that persistently harsh environmental conditions impeded the biotic recovery during the Early Triassic, our new findings, combined with recent work, indicate a fitful regional recovery pattern after the Permian-Triassic crisis, resulting in three main diversity highs: late Griesbachian–early Dienerian, early–middle Smithian, and Spathian. The transient rebound episodes were therefore influenced by both extrinsic local (e.g., redox condition, temperature) and intrinsic (e.g., biological tolerances, origination rates) parameters

Alginate Adsorbent Immobilization Technique Promotes Biobutanol Production by Clostridium acetobutylicum Under Extreme Condition of High Concentration of Organic Solvent

In Acetone-Butanol-Ethanol fermentation, bacteria should tolerate high concentrations of solvent products, which inhibit bacteria growth and limit further increase of solvents to more than 20 g/L. Moreover, this limited solvent concentration significantly increases the cost of solvent separation through traditional approaches. In this study, alginate adsorbent immobilization technique was successfully developed to assist in situ extraction using octanol which is effective in extracting butanol but presents strong toxic effect to bacteria. The adsorbent improved solvent tolerance of Clostridium acetobutylicum under extreme condition of high concentration of organic solvent. Using the developed technique, more than 42% of added bacteria can be adsorbed to the adsorbent. Surface area of the adsorbent was more than 10 times greater than sodium alginate. Scanning electron microscope image shows that an abundant amount of pore structure was successfully developed on adsorbents, promoting bacteria adsorption. In adsorbent assisted ABE fermentation, there was 21.64 g/L butanol in extracting layer compared to negligible butanol produced with only the extractant but without the adsorbent, for the reason that adsorbent can reduce damaging exposure of C. acetobutylicum to octanol. The strategy can improve total butanol production with respect to traditional culture approach by more than 2.5 fold and save energy for subsequent butanol recovery, which effects can potentially make the biobutanol production more economically practical

Calibrating the late Smithian (Early Triassic) crisis: new insights from the Nanpanjiang Basin, South China.

17 pagesInternational audienceThe biotic recovery following the Permian/Triassic boundary mass extinction was influenced by several secondary extinctions during the Early Triassic, of which the late Smithian crisis is the most severe known for some nekto-pelagic organisms such as ammonoids. The Smithian-Spathian transition is characterized by successive global biotic and environmental changes, including a dramatic positive carbon isotopic excursion, oceanic anoxia and a cooling event beginning in the late Smithian. However, the tempo, modalities and the causal relationships among these various events remain poorly constrained. Here we synthesized paleontological, sedimentological, and geochemical data from three sections (Motianling, Nafang, and Shanggang) within the Nanpanjiang Basin, representing platform slop to basinal deposits spanning the Smithian/Spathian boundary. High-resolution analyses of thin sections show a sudden decrease in richness and abundance of fossil grains at the middle/upper Smithian boundary in all three sections, coinciding with the onset of a positive shift in δ13Ccarb. It also slightly precedes the beginning of the late Smithian cooling. At Shanggang, a change in dominance from bivalve-rich to ostracod-rich strata is also recorded at the middle/upper Smithian boundary. Overall, our results therefore indicate that a first major biotic crisis and turnover happened during the beginning of the late Smithian in the Nanpanjiang Basin, rather than around the Smithian/Spathian boundary. Complementary analyses on pyrite framboid size indicate that these observed biotic changes are concurrent with oxygen depletion in the studied sections, supporting the hypothesis that oceanic anoxia also played an important role in the late Smithian crisis in combination with climate cooling and oceanic acidification