Within-patch and edge microclimates vary over a growing season and are amplified during a heatwave: Consequences for ectothermic insects.

Embedded in longer term warming are extreme climatic events such as heatwaves and droughts that are increasing in frequency, duration and intensity. Changes in climate attributes such as temperature are often measured over larger spatial scales, whereas environmental conditions to which many small ectothermic arthropods are exposed are largely determined by small-scale local conditions. Exposed edges of plant patches often exhibit significant short-term (daily) variation to abiotic factors due to wind exposure and sun radiation. By contrast, within plant patches, abiotic conditions are generally much more stable and thus less variable. Over an eight-week period in the summer of 2020, including an actual heatwave, we measured small-scale (1 m2) temperature variation in patches of forbs in experimental mesocosms. We found that soil surface temperatures at the edge of the mesocosms were more variable than those within mesocosms. Drought treatment two years earlier, amplified this effect but only at the edges of the mesocosms. Within a plant patch both at the soil surface and within the canopy, the temperature was always lower than the ambient air temperature. The temperature of the soil surface at the edge of a patch may exceed the ambient air temperature when ambient air temperatures rise above 23 °C. This effect progressively increased with ambient temperature. We discuss how microscale-variation in temperature may affect small ectotherms such as insects that have limited ability to thermoregulate, in particular under conditions of extreme heat.

Zwitterionic amidinates as effective ligands for platinum nanoparticle hydrogenation catalysts.

Ligand control of metal nanoparticles (MNPs) is rapidly gaining importance as ligands can stabilize the MNPs and regulate their catalytic properties. Herein we report the first example of Pt NPs ligated by imidazolium-amidinate ligands that bind strongly through the amidinate anion to the platinum surface atoms. The binding was established by 15N NMR spectroscopy, a precedent for nitrogen ligands on MNPs, and XPS. Both monodentate and bidentate coordination modes were found. DFT showed a high bonding energy of up to -48 kcal mol-1 for bidentate bonding to two adjacent metal atoms, which decreased to -28 ± 4 kcal mol-1 for monodentate bonding in the absence of impediments by other ligands. While the surface is densely covered with ligands, both IR and 13C MAS NMR spectra proved the adsorption of CO on the surface and thus the availability of sites for catalysis. A particle size dependent Knight shift was observed in the 13C MAS NMR spectra for the atoms that coordinate to the surface, but for small particles, ∼1.2 nm, it almost vanished, as theory for MNPs predicts; this had not been experimentally verified before. The Pt NPs were found to be catalysts for the hydrogenation of ketones and a notable ligand effect was observed in the hydrogenation of electron-poor carbonyl groups. The catalytic activity is influenced by remote electron donor/acceptor groups introduced in the aryl-N-substituents of the amidinates; p-anisyl groups on the ligand gave catalysts several times faster the ligand containing p-chlorophenyl groups.

Long-chain NHC-stabilized RuNPs as versatile catalysts for one-pot oxidation/hydrogenation reactions.

The synthesis and catalytic activity of long-chain NHC-stabilized RuNPs are presented. Full characterization of these novel nanostructures including surface state studies show that the ligand influences the number and the location of Ru active sites which impacts the NP catalytic activity, especially in hydrogenation reactions. The high stability and versatility of these nanosystems make them successful catalysts for both oxidation and hydrogenation reactions that can even be performed successively in a one pot-fashion.

A betaine adduct of N-heterocyclic carbene and carbodiimide, an efficient ligand to produce ultra-small ruthenium nanoparticles.

The betaine adduct of N-heterocyclic carbene and carbodiimide (ICy·((p-tol))NCN) was found to be a very efficient ligand to prepare very small (1-1.3 nm) ruthenium nanoparticles (RuNPs). The coordination of the ligand on the metal surface takes place through the carbodiimide moiety. The resulting RuNPs led to decarbonylation of THF and showed size selectivity for styrene hydrogenation.

Estrogen and progesterone lower cyclin B1 AND D1 expression, block cell cycle in G2/M, and trigger apoptosis in human adrenal carcinoma cell cultures.

The effects of 17 beta-estradiol and progesterone were evaluated separately and in combination, on the growth, survival, and cell cycle dynamics of SW-13 human adrenal carcinoma cells in culture. Both hormones significantly decreased cell survival, with dose response curves at four days demonstrating EC (50)s estimated at 1.2 x 10 (-5) M for 17 beta-estradiol and 4.8 x 10 (-6) M for progesterone. Flow cytometry studies of these cultures indicated a strong G2/M blocking effect of both steroids, either individually or in combination; the effects of progesterone and of both agents together were substantially greater than the effect with 17 beta-estradiol alone. The sub-G1 region of the flow cytometry profile was significantly enhanced by exposure to 17 beta-estradiol and even more by progesterone. Sub-G1 "apoptosis" was confirmed by fragmented and condensed nuclear chromatin staining using a standard DAPI fluorescence assay. The expression of the critical cell cycle regulatory proteins cyclin B1 and D1 were significantly decreased by each hormone, with the influence of progesterone again predominating. These data demonstrate that high doses of 17 beta-estradiol and progesterone have inhibitory and apoptotic effects on SW-13 human adrenal carcinoma cells IN VITRO. The observed effects are associated with declines in cyclin B1 and D1 expression as well as a block in G2/M.

High dose 17 beta-estradiol and the alpha-estrogen agonist PPT trigger apoptosis in human adrenal carcinoma cells but the beta-estrogen agonist DPN does not.

Previous studies have shown that high dose 17beta-estradiol (10 (-5) M) has a G2/M blocking effect in SW-13 human adrenal carcinoma cultures and strongly enhances apoptosis. To examine the differential effects of estrogen alpha and beta-receptors in this system, we incubated SW-13 cells with specific alpha- and beta-estrogen receptor agonists, PPT [4,4',4''-(propyl-[ (1)H]-pyrazole-1,3,5-triyl) trisphenol] and DPN [2,3-bis (4-hydroxyphenyl) propionitrile], respectively (each at 10 (-5) M). Flow cytometry was used to analyze the percentages of cells in various phases of the cell cycle [sub-G1 (apoptosis), G1, S, and G2/M] in each experimental condition. Exposure to 17 beta-estradiol for 48 hours increased apoptosis more than 5-fold (from 3.6+/-0.5 to 20+/-2.2% of cells; p<0.01). The alpha-estrogen agonist PPT had a similar effect, increasing apoptosis to 22+/-1.7% (p<0.01), but the beta-agonist DPN caused no change (3.6+/-0.5 vs. 3.9+/-0.8%). While estrogen and the alpha-estrogen agonist decrease apoptosis in this system, both of these compounds decreased the percentage of cells in G1 (from 59+/-1.4% for control to 34+/-2.3% for estrogen and 40+/-2.0% for PPT; p<0.01 for both agents relative to control); the beta-agonist again had no effect. Estrogen was also found to block the cell cycle in G2/M, increasing it from 15+/-0.4 to 21+/-1.0% of cells (p<0.01), but neither the alpha- nor beta-estrogen agonists had any effect at this point in the cell cycle, indicating that the influence of estrogen was not likely to be either alpha- or beta-receptor mediated. There was no apparent effect of any of these agents on DNA synthesis, as indicated by unchanged percentages of cells in S phase. These studies suggest that induction of apoptosis by estrogen in SW-13 human adrenal cortical carcinoma cultures is mediated by the alpha-receptor, but the G2/M blocking effect of estrogen is not likely to be related to either alpha or beta mechanisms.

Ethnic differences in plantar pressures in diabetic patients with peripheral neuropathy.

AIMS: To compare plantar foot pressures between Caucasian and Hispanic diabetic patients with peripheral neuropathy (PN) without a history of foot ulceration and between Caucasian and Hispanic non-diabetic individuals. METHODS: Forty-four Hispanic diabetic patients with PN (HDPN), 35 Caucasian diabetic patients with PN (CDPN), 41 non-diabetic Hispanic subjects and 33 non-diabetic Caucasian subjects participated. Total and regional peak plantar pressures (PPs) and pressure time integrals (PTIs) were assessed using the EMED-SF-4 plantar pressure system. RESULTS: Hispanic diabetic patients with PN had significantly lower peak PP than Caucasian diabetic patients with PN in the entire foot (552.4 +/- 227.9 vs. 810.1 +/- 274.6 kPa; P < 0.001), forefoot (464.1 +/- 222.6 vs. 699.6 +/- 323.1 kPa; P < 0.001), hindfoot (296.3.4 + 101.8 vs. 398.1 + 178.3 kPa; P < 0.01) and at the fifth metatarsal head (MTH5; 204.3 +/- 143.2 vs. 388.2 +/- 273.9 kPa; P < 0.001). The PTI in the entire foot, forefoot and MTH5 were also lower in HDPN than in CDPN. The ethnic differences between the diabetic groups with PN for the entire foot, forefoot and MTH5 remained significant after adjusting for the effect of age, gender, weight and duration of diabetes. There were no significant differences in peak PP and PTI among non-diabetic individuals, except for a lower peak PP at the MTH5 in Hispanic compared with Caucasian subjects. CONCLUSIONS: Despite a well-known higher incidence of foot complications in diabetic Hispanic subjects, dynamic plantar pressures are lower in Hispanic diabetic patients with PN when compared with their Caucasian counterparts, suggesting that differences in other risk factors exist between these two ethnic groups.

The production of rhamnolipid by a Pseudomonas aeruginosa strain isolated from a southern coastal zone in Brazil.

The production and properties of a rhamnolipid-type biosurfactant, synthesized by the Pseudomonas aeruginosa LBM10 strain, isolated from a southern coastal zone in Brazil, were investigated. The assays were conducted in a rotary shaker at 30 degrees C and 180 rpm for a period of 96 h. Soybean oil and sodium nitrate were the best sources of carbon and nitrogen, respectively. A nitrogen-limiting condition (C/N ratio of 100) was favorable to biosurfactant production. The formation of stable emulsions was better in saline concentrations below 0.5%, pH values in the range from 6 to 9 and temperatures in the range from 35 to 40 degrees C, maintaining about 80% of its original activity for salinity up to 3% and 120 min of exposure at 100 degrees C. The biosurfactant may be produced with this microorganism using renewable substrates that are readily available, reaching values of 1.42 g l(-1) measured as rhamnose. This biosurfactant has interesting and useful properties for many industrial applications.

Relation between the presence of echocardiographic vegetations and the complication rate in infective endocarditis.

M-mode and two-dimensional echocardiograms of 77 patients with infective endocarditis were examined to determine if presence and/or size of vegetations on echocardiogram were predictive of morbidity and mortality. Patients with (n = 43) or without (n = 34) vegetations on echocardiogram did not differ significantly in the proportions developing congestive heart failure (23 of 43 or 53% vs 12 of 34 or 35%) or emboli (11 of 43 or 24% vs 6 of 34 or 18%), whereas a slightly lower proportion of those with vegetations required surgery (5 of 43 or 12% vs 7 of 34 or 21%) or died (3 of 43 or 7% vs 4 of 34 or 12%). No significant relationship was found between vegetation size and the frequency of complications, the need for surgery, or death. In contrast, patients whose echocardiograms demonstrated premature mitral valve closure or chordal or cusp rupture had a significantly higher incidence of heart failure (10 of 13 or 77% vs 22 of 60 or 37%, p less than 0.003) and surgery (3 of 13 or 23% vs 7 of 60 or 12%, p less than 0.05). We conclude that: the presence of vegetation on the initial echocardiogram is not predictive of the clinical course in infective endocarditis; vegetation size does not predict complications, need for surgery, or death; but valve cusp or chordal rupture and/or premature mitral valve closure are associated with congestive heart failure and the need for surgery.