Phosphido pincer complexes of platinum: synthesis, structure and reactivity

A series of platinum(II) complexes supported by the tridentate bis(phosphine)phosphido ligand bis(2-diisopropylphosphinophenyl)phosphide) [iPr–PPP] have been synthesized and characterized (1–4). X-Ray structural studies of [iPr–PPP]PtCl (1) and [iPr–PPP]PtCH3 (3) complexes show meridional [iPr–PPP] ligands around approximately square-planar platinum centers. Structural data and NMR analysis highlight a strong trans influence for the phosphido phosphorous donor, comparable to that of the anionic aryl carbon of the classic PCP pincer complexes. A series of thermally stable [PPP]Pt(IV) compounds, including [PPP]Pt(CH_3)_2X [X = I (5) and SbF_6 (6)], were also synthesized. The study of the binding affinity of SO_2 and NO to complex 1 has also been addressed

A nitrite microsensor for profiling environmental biofilms

A highly selective liquid membrane nitrite microsensor based on the hydrophobic ion-carrier aquocyano-cobalt(III) -hepta(2-phenylethyl)-cobrynate is described, The sensor has a tip diameter of 10 to 15 mu m. The response is log-linear in freshwater down to 1 mu M NO2- and in seawater to 10 mu M NO2-. A method is described for preparation of relatively large polyvinyl chloride (PVC)-gelled liquid membrane microsensors with a tip diameter of 5 to 15 mu m, having a hydrophilic coating on the tip, The coating and increased tip diameter resulted in more sturdy sensors, with a lower detection limit and a more stable signal than uncoated nitrite sensors with a tip diameter of 1 to 3 mu m. The coating protects the sensor membrane from detrimental direct contact with biomass and can be used for all PVC-gelled liquid membrane sensors meant for profiling microbial mats, biofilms, and sediments. Thanks to these improvements, liquid membrane sensors can now be used in complex environmental samples and in situ, e.g., in operating bioreactors. Examples of measurements in denitrifying, nitrifying, and nitrifying/denitrifying biofilms from wastewater treatment plants are shown. In all of these biofilms high nitrite concentrations were found in narrow zones of less than 1 mm

An Examination of Brønsted-Acid Sites in H-[Fe]ZSM-5 for Olefin Oligomerization and Adsorption

The adsorption and reaction properties of an Al-free H-[Fe]ZSM-5 were examined and compared to an H-[Al]ZSM-5 sample with the same site density. H-[Fe]ZSM-5 was shown to have Brønsted-acid sites in a concentration equal to the framework Fe concentration. Differential heats of adsorption for ammonia and pyridine were shown to be identical to that obtained in H-[Al]ZSM-5, with differential heats of ~150 kJ/mol for ammonia and 200 kJ/mol for pyridine. For H-[Al]ZSM-5, adsorption of either propylene or 1-butene at room temperature results in rapid oligomerization. TPD-TGA measurements of the oligomers in H-[Al]ZSM-5 show evidence for hydride-transfer reactions, in addition to simple oligomer cracking. By contrast, it is necessary to heat H-[Fe]ZSM-5 to 370 K for rapid oligomerization of propylene and oligomerization of 1-butene occurs only slowly at 295 K. TPD-TGA measurements of the oligomers in H-[Fe]ZSM-5 show no evidence for hydride-transfer reactions and H-[Fe]ZSM-5 forms much less coke than H-[Al]ZSM-5 during steady-state reaction in 1-butene at 573 K. Adsorption measurements of 1-butene on D-[Fe]ZSM-5 suggest that the protonated complexes of 1-butene are formed but that these are relatively stable towards reaction, implying that the carbocation transition states are relatively unstable

Bio-optical properties and radiative energy budgets in fed and unfed scleractinian corals (Pocillopora sp.) during thermal bleaching

© 2019 The authors. Corals live in symbiosis with algal dinoflagellates, which can achieve outstanding photo - synthetic energy efficiencies in hospite approaching theo retical limits. However, how such photosynthetic efficiency varies with environmental stress remains poorly known. Using fiber-optic and electrochemical microsensors in combination with variable chlorophyll fluorescence imaging, we investigated the combined effects of thermal stress and active feeding on the radiative energy budget and photosynthetic efficiency of the symbiotic coral Pocillopora sp. At ambient temperature (25°C), the percentage of ab sorbed light energy used for photosynthesis under low irradiance was higher for fed (∼5-6%) compared to unfed corals (4%). Corals from both feeding treatments responded equally to stress from high light ex posure (2400 μmol photons m-2 s-1), exhibiting a de crease in photosynthetic efficiency, down to 0.5-0.6%. Fed corals showed increased resilience to thermal-induced bleaching (loss of symbionts) compared to unfed corals. In addition, while unfed corals decreased their photosynthetic efficiency almost immediately when exposed to thermal stress, fed corals maintained a constant and high photosynthetic efficiency for 5 more days after onset of thermal stress. We conclude that active feeding is beneficial to corals by prolonging coral health and resilience during thermal stress as a result of an overall healthier symbiont population

Effective sociodemographic population assessment of elusive species in ecology and conservation management

Wildlife managers are urgently searching for improved sociodemographic population assessment methods to evaluate the effectiveness of implemented conservation activities. These need to be inexpensive, appropriate for a wide spectrum of species and straightforward to apply by local staff members with minimal training. Furthermore, conservation management would benefit from single approaches which cover many aspects of population assessment beyond only density estimates, to include for instance social and demographic structure, movement patterns, or species interactions. Remote camera traps have traditionally been used to measure species richness. Currently, there is a rapid move toward using remote camera trapping in density estimation, community ecology, and conservation management. Here, we demonstrate such comprehensive population assessment by linking remote video trapping, spatially explicit capture–recapture (SECR) techniques, and other methods. We apply it to three species: chimpanzees Pan troglodytes troglodytes, gorillas Gorilla gorilla gorilla, and forest elephants Loxodonta cyclotis in Loango National Park, Gabon. All three species exhibited considerable heterogeneity in capture probability at the sex or group level and density was estimated at 1.72, 1.2, and 1.37 individuals per km(2) and male to female sex ratios were 1:2.1, 1:3.2, and 1:2 for chimpanzees, gorillas, and elephants, respectively. Association patterns revealed four, eight, and 18 independent social groups of chimpanzees, gorillas, and elephants, respectively: key information for both conservation management and studies on the species' ecology. Additionally, there was evidence of resident and nonresident elephants within the study area and intersexual variation in home range size among elephants but not chimpanzees. Our study highlights the potential of combining camera trapping and SECR methods in conducting detailed population assessments that go far beyond documenting species diversity patterns or estimating single species population size. Our study design is widely applicable to other species and spatial scales, and moderately trained staff members can collect and process the required data. Furthermore, assessments using the same method can be extended to include several other ecological, behavioral, and demographic aspects: fission and fusion dynamics and intergroup transfers, birth and mortality rates, species interactions, and ranging patterns

Permissive expansion and homing of adoptively transferred T cells in tumor-bearing hosts

Activated T cells expressing endogenous or transduced TCRs are two cell types currently used in clinical adoptive T-cell therapy. The ability of these cells to recognize their antigen, expand, and traffic to the tumor site are the initial steps necessary for successful therapy. In this study, we used in vivo bioluminescent imaging (BLI) of Renilla luciferase (RLuc) expressing T cells to evaluate the ability of adoptively transferred T cells to survive, expand and home to tumor site in vivo. Using this method, termed RT-Rack (Rluc T cell tracking), we followed T-cell response against tumors in vivo. Expansion and homing of adoptively transferred T cells were antigen dependent, but independent of the host immune status. Moreover, we successfully detected T-cell response to small and large tumors, including autochthonous liver tumors. The adoptively transferred T cells were not ignorant or excluded in a partially tolerant host, which expressed low level of the target in the periphery. Using T cell receptor-engineered T cells, we showed the ability of these cells to respond in tumor-bearing hosts by expanding and homing to the tumor site. In all these models, the host immune status, the nature of the tumor or of the antigen, the tumor size, and the presence of the targeted antigen in the periphery did not prevent the adoptively transferred T cells from responding by expanding and homing to the tumor. However, T cells had higher expression of the inhibitory receptor PD1 and reduced functional activity when a self-antigen was targeted

Music Piracy: Bad for Record Sales but Good for the iPod?

Music piracy is a double-edged sword for the music industry. On the one hand, it hurts record sales. On the other hand, it increases sales of its complements. To quantify the effect of music piracy, I construct a unique survey data set and use a Bayesian method to estimate the demand for music and iPods, and find three things. First, music piracy decreases music sales by 24% to 42%. Second, music piracy contributes 12% to iPod sales. Finally, counterfactual experiments show that Apple's revenue could increase by $36 per student if music were free