A fundamental aspect of any element is the range of oxidation states accessible for useful chemistry. This tutorial describes the recent expansion of the number of oxidation states available to the ...rare-earth and actinide metals in molecular complexes that has resulted through organometallic chemistry involving the cyclopentadienyl ligand. These discoveries demonstrate that the cyclopentadienyl ligand, which has been a key component in the development of organometallic chemistry since the seminal discovery of ferrocene in the 1950s, continues to contribute to the advancement of science. Background information on the rare-earth and actinide elements is presented, as well as the sequence of events that led to these unexpected developments in the oxidation state chemistry of these metals.
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Pyrolysis is one of the thermochemical technologies for converting biomass into energy and chemical products consisting of liquid bio-oil, solid biochar, and pyrolytic gas. Depending on the heating ...rate and residence time, biomass pyrolysis can be divided into three main categories slow (conventional), fast and flash pyrolysis mainly aiming at maximising either the bio-oil or biochar yields. Synthesis gas or hydrogen-rich gas can also be the target of biomass pyrolysis. Maximised gas rates can be achieved through the catalytic pyrolysis process, which is now increasingly being developed. Biomass pyrolysis generally follows a three-step mechanism comprising of dehydration, primary and secondary reactions. Dehydrogenation, depolymerisation, and fragmentation are the main competitive reactions during the primary decomposition of biomass. A number of parameters affect the biomass pyrolysis process, yields and properties of products. These include the biomass type, biomass pretreatment (physical, chemical, and biological), reaction atmosphere, temperature, heating rate and vapour residence time. This manuscript gives a general summary of the properties of the pyrolytic products and their analysis methods. Also provided are a review of the parameters that affect biomass pyrolysis and a summary of the state of industrial pyrolysis technologies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Assessment of the global burden of disease is based on epidemiological cohort studies that connect premature mortality to a wide range of causes, including the long-term health impacts of ozone and ...fine particulate matter with a diameter smaller than 2.5 micrometres (PM2.5). It has proved difficult to quantify premature mortality related to air pollution, notably in regions where air quality is not monitored, and also because the toxicity of particles from various sources may vary. Here we use a global atmospheric chemistry model to investigate the link between premature mortality and seven emission source categories in urban and rural environments. In accord with the global burden of disease for 2010 (ref. 5), we calculate that outdoor air pollution, mostly by PM2.5, leads to 3.3 (95 per cent confidence interval 1.61-4.81) million premature deaths per year worldwide, predominantly in Asia. We primarily assume that all particles are equally toxic, but also include a sensitivity study that accounts for differential toxicity. We find that emissions from residential energy use such as heating and cooking, prevalent in India and China, have the largest impact on premature mortality globally, being even more dominant if carbonaceous particles are assumed to be most toxic. Whereas in much of the USA and in a few other countries emissions from traffic and power generation are important, in eastern USA, Europe, Russia and East Asia agricultural emissions make the largest relative contribution to PM2.5, with the estimate of overall health impact depending on assumptions regarding particle toxicity. Model projections based on a business-as-usual emission scenario indicate that the contribution of outdoor air pollution to premature mortality could double by 2050.
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An operando electrochemical stage for the transmission electron microscope has been configured to form a “Li battery” that is used to quantify the electrochemical processes that occur at the anode ...during charge/discharge cycling. Of particular importance for these observations is the identification of an image contrast reversal that originates from solid Li being less dense than the surrounding liquid electrolyte and electrode surface. This contrast allows Li to be identified from Li-containing compounds that make up the solid-electrolyte interphase (SEI) layer. By correlating images showing the sequence of Li electrodeposition and the evolution of the SEI layer with simultaneously acquired and calibrated cyclic voltammograms, electrodeposition, and electrolyte breakdown processes can be quantified directly on the nanoscale. This approach opens up intriguing new possibilities to rapidly visualize and test the electrochemical performance of a wide range of electrode/electrolyte combinations for next generation battery systems.
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We review progress over the past decade in observations of large-scale star formation, with a focus on the interface between extragalactic and Galactic studies. Methods of measuring gas contents and ...star-formation rates are discussed, and updated prescriptions for calculating star-formation rates are provided. We review relations between star formation and gas on scales ranging from entire galaxies to individual molecular clouds.
ABSTRACT The total gas mass of a protoplanetary disk is a fundamental, but poorly determined, quantity. A new technique has been demonstrated to assess directly the bulk molecular gas reservoir of ...molecular hydrogen using the HD J = 1-0 line at 112 m. In this work we present a Herschel Space Observatory10 survey of six additional T Tauri disks in the HD line. Line emission is detected at >3 significance in two cases: DM Tau and GM Aur. For the other four disks, we establish upper limits to the line flux. Using detailed disk structure and ray-tracing models, we calculate the temperature structure and dust mass from modeling the observed spectral energy distributions, and we include the effect of UV gas heating to determine the amount of gas required to fit the HD line. The ranges of gas masses are 1.0-4.7 × 10−2 for DM Tau and 2.5-20.4 × 10−2 for GM Aur. These values are larger than those found using CO for GM Aur, while the CO-derived gas mass for DM Tau is consistent with the lower end of our mass range. This suggests a CO chemical depletion from the gas phase of up to a factor of five for DM Tau and up to two orders of magnitude for GM Aur. We discuss how future analysis can narrow the mass ranges further.
After the Holocaust, the world vowed it would never again stand by and permit such heinous crimes against humanity. Yet many subsequent atrocities have gone unchecked, all over the world: from the ...killing fields of Cambodia, to Rwanda, and to Srebrenica. The bloody list continues to grow, led by the unfolding nightmare in Darfur. How and why were the world's best intentions derailed, and what can be done today to put these efforts back on track? The "responsibility to protect: - R2P for short - was unanimously embraced at the UN World Summit in 2005. The heart of this new international norm is the belief that if sovereign governments fail to protect their own people from mass atrocity crimes, then responsibility shifts to the wider international community to take whatever action is appropriate, including (in extreme cases) the use of force. The world cannot, and will not, just stand by. Evens spells out the steps needed to make R2P work in practice and clarifies the misunderstandings, real or contrived, which persist about its scope and limits. He emphasizes the need for preventive action, and for preferring assistance and persuasion to coercion, but he also makes clear when it is right to fight. The book is enlivened throughout by real world examples, analyses of current events, and assessments drawn from the author's own vast experience.
We discuss the parameter spaces of supersymmetry (SUSY) scenarios taking into account the improved Higgs-mass prediction provided by FeynHiggs 2.14.1. Among other improvements, this prediction ...incorporates three-loop renormalization-group effects and two-loop threshold corrections, and can accommodate three separate mass scales:
m
q
~
(for squarks),
m
g
~
(for gluinos) and
m
χ
~
(for electroweakinos). Furthermore, it contains an improved treatment of the
DR
¯
scalar top parameters avoiding problems with the conversion to on-shell parameters, that yields more accurate results for large SUSY-breaking scales. We first consider the CMSSM, in which the soft SUSY-breaking parameters
m
0
and
m
1
/
2
are universal at the GUT scale, and then sub-GUT models in which universality is imposed at some lower scale. In both cases, we consider the constraints from the Higgs-boson mass
M
h
in the bulk of the
(
m
0
,
m
1
/
2
)
plane and also along stop coannihilation strips where sparticle masses may extend into the multi-TeV range. We then consider the minimal anomaly-mediated SUSY-breaking scenario, in which large sparticle masses are generic. In all these scenarios the substantial improvements between the calculations of
M
h
in FeynHiggs 2.14.1 and FeynHiggs 2.10.0, which was used in an earlier study, change significantly the preferred portions of the models’ parameter spaces. Finally, we consider the pMSSM11, in which sparticle masses may be significantly smaller and we find only small changes in the preferred regions of parameter space.
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Abstract
Drylands cover 41% of the earth’s land surface and include 45% of the world’s agricultural land. These regions are among the most vulnerable ecosystems to anthropogenic climate and land use ...change and are under threat of desertification. Understanding the roles of anthropogenic climate change, which includes the CO
2
fertilization effect, and land use in driving desertification is essential for effective policy responses but remains poorly quantified with methodological differences resulting in large variations in attribution. Here, we perform the first observation-based attribution study of desertification that accounts for climate change, climate variability, CO
2
fertilization as well as both the gradual and rapid ecosystem changes caused by land use. We found that, between 1982 and 2015, 6% of the world’s drylands underwent desertification driven by unsustainable land use practices compounded by anthropogenic climate change. Despite an average global greening, anthropogenic climate change has degraded 12.6% (5.43 million km
2
) of drylands, contributing to desertification and affecting 213 million people, 93% of who live in developing economies.
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