Summary
The soil is important in sequestering atmospheric CO2 and in emitting trace gases (e.g. CO2, CH4 and N2O) that are radiatively active and enhance the ‘greenhouse’ effect. Land use changes and ...predicted global warming, through their effects on net primary productivity, the plant community and soil conditions, may have important effects on the size of the organic matter pool in the soil and directly affect the atmospheric concentration of these trace gases.
A discrepancy of approximately 350 × 1015 g (or Pg) of C in two recent estimates of soil carbon reserves worldwide is evaluated using the geo‐referenced database developed for the World Inventory of Soil Emission Potentials (WISE) project. This database holds 4353 soil profiles distributed globally which are considered to represent the soil units shown on a ½º latitude by ½º longitude version of the corrected and digitized 1 : 5 M FAO–UNESCO Soil Map of the World.
Total soil carbon pools for the entire land area of the world, excluding carbon held in the litter layer and charcoal, amounts to 2157–2293 Pg of C in the upper 100 cm. Soil organic carbon is estimated to be 684–724 Pg of C in the upper 30 cm, 1462–1548 Pg of C in the upper 100 cm, and 2376–2456 Pg of C in the upper 200 cm. Although deforestation, changes in land use and predicted climate change can alter the amount of organic carbon held in the superficial soil layers rapidly, this is less so for the soil carbonate carbon. An estimated 695–748 Pg of carbonate‐C is held in the upper 100 cm of the world's soils. Mean C : N ratios of soil organic matter range from 9.9 for arid Yermosols to 25.8 for Histosols. Global amounts of soil nitrogen are estimated to be 133–140 Pg of N for the upper 100 cm. Possible changes in soil organic carbon and nitrogen dynamics caused by increased concentrations of atmospheric CO2 and the predicted associated rise in temperature are discussed.
Transition metal catalysis in confined spaces Leenders, Stefan H. A. M; Gramage-Doria, Rafael; de Bruin, Bas ...
Chemical Society reviews,
01/2015, Volume:
44, Issue:
2
Journal Article
Peer reviewed
Open access
Transition metal catalysis plays an important role in both industry and in academia where selectivity, activity and stability are crucial parameters to control. Next to changing the structure of the ...ligand, introducing a confined space as a second coordination sphere around a metal catalyst has recently been shown to be a viable method to induce new selectivity and activity in transition metal catalysis. In this review we focus on supramolecular strategies to encapsulate transition metal complexes with the aim of controlling the selectivity
via
the second coordination sphere. As we will discuss, catalyst confinement can result in selective processes that are impossible or difficult to achieve by traditional methods. We will describe the template-ligand approach as well as the host-guest approach to arrive at such supramolecular systems and discuss how the performance of the catalyst is enhanced by confining it in a molecular container.
This review discusses different strategies to provide transition metal catalysts with a second coordination sphere and the effect this has in catalysis.
•A review on the applications of artificial intelligence on battling against covid-19 is performed.
Colloquially known as coronavirus, the Severe Acute Respiratory Syndrome CoronaVirus 2 ...(SARS-CoV-2), that causes CoronaVirus Disease 2019 (COVID-19), has become a matter of grave concern for every country around the world. The rapid growth of the pandemic has wreaked havoc and prompted the need for immediate reactions to curb the effects. To manage the problems, many research in a variety of area of science have started studying the issue. Artificial Intelligence is among the area of science that has found great applications in tackling the problem in many aspects. Here, we perform an overview on the applications of AI in a variety of fields including diagnosis of the disease via different types of tests and symptoms, monitoring patients, identifying severity of a patient, processing covid-19 related imaging tests, epidemiology, pharmaceutical studies, etc. The aim of this paper is to perform a comprehensive survey on the applications of AI in battling against the difficulties the outbreak has caused. Thus we cover every way that AI approaches have been employed and to cover all the research until the writing of this paper. We try organize the works in a way that overall picture is comprehensible. Such a picture, although full of details, is very helpful in understand where AI sits in current pandemonium. We also tried to conclude the paper with ideas on how the problems can be tackled in a better way and provide some suggestions for future works.
With observations of the Interface Region Imaging Spectrograph (IRIS), we study chromospheric heating and evaporation during an M1.6 flare SOL2015-03-12T11:50. At the flare ribbons, the Mg ii 2791.59 ...line shows quasi-periodic short-duration red-wing enhancement, which is likely related to repetitive chromospheric condensation as a result of episodic heating. On the contrary, the Si iv 1402.77 line reveals a persistent red-wing asymmetry in both the impulsive and decay phases, suggesting that this line responds to both cooling downflows and chromospheric condensation. The first two episodes of red-wing enhancement occurred around 11:42 UT and 11:45 UT, when two moving brightenings indicative of heating fronts crossed the IRIS slit. The greatly enhanced red wings of the Si iv and Mg ii lines at these occasions are accompanied by an obvious increase in the line intensities and the HXR flux, suggesting two episodes of energy injection into the lower atmosphere in the form of nonthermal electrons. The Mg ii k/h ratio has a small value of ∼1.2 at the ribbons and decreases to ∼1.1 at these two occasions. Correspondingly, the Fe xxi 1354 line reveals two episodes of chromospheric evaporation, which is characterized as a smooth decrease of the blueshift from ∼300 km s−1 to nearly zero within ∼3 minutes. The Fe xxi 1354 line is entirely blueshifted in the first episode, while it appears to contain a nearly stationary component and a blueshifted component in the second episode. Additional episodes of blueshifted Fe xxi emission are found around the northern ribbon in the decay phase, though no obvious response is detected in the Si iv and Mg ii emission. We have also examined the Fe xxi emission at the flare loop top and identified a secondary component with a ∼200 km s−1 redshift, which possibly results from the downward moving reconnection outflow. Our analysis also yields a rest wavelength of 1354.0878 0.0072 for this Fe xxi line.
We evaluated the inhibitory effects of the probiotic
Lactobacillus
species on different phases of
Candida albicans
biofilm development. Quantification of biofilm growth and ultrastructural analyses ...were performed on
C. albicans
biofilms treated with
Lactobacillus rhamnosus
,
Lactobacillus casei
, and
Lactobacillus acidophilus
planktonic cell suspensions as well as their supernatants. Planktonic lactobacilli induced a significant reduction (
p
< 0.05) in the number of biofilm cells (25.5–61.8 %) depending on the probiotic strain and the biofilm phase.
L. rhamnosus
supernatants had no significant effect on the mature biofilm (
p
> 0.05), but significantly reduced the early stages of
Candida
biofilm formation (
p
< 0.01). Microscopic analyses revealed that
L. rhamnosus
suspensions reduced
Candida
hyphal differentiation, leading to a predominance of budding growth. All lactobacilli negatively impacted
C. albicans
yeast-to-hyphae differentiation and biofilm formation. The inhibitory effects of the probiotic
Lactobacillus
on
C. albicans
entailed both cell-cell interactions and secretion of exometabolites that may impact on pathogenic attributes associated with
C. albicans
colonization on host surfaces and yeast filamentation. This study clarifies, for the first time, the mechanics of how
Lactobacillus
species may antagonize
C. albicans
host colonization. Our data elucidate the inhibitory mechanisms that define the probiotic candicidal activity of lactobacilli, thus supporting their utility as an adjunctive therapeutic mode against mucosal candidal infections.
Summary
Background
Up‐to‐date information regarding the recurrence rate of Helicobacter pylori (H. pylori) after eradication therapy is not available.
Aim
To evaluate the global recurrence rate ...following H. pylori eradication therapy and confirm its association with socioeconomic and sanitary conditions.
Methods
A systematic search of PubMed, EMBASE and the Cochrane library was performed to identify potentially relevant publications using the following keywords: “Helicobacter pylori” or “H. pylori” or “Hp” and “recurrence” or “recrudescence” or “reinfection” or “recurrent” or “recurred” or “re‐infect*” or “relapse*.”
Results
A total of 132 studies (53 934 patient‐years) were analysed. Each study was weighted according to the duration of patient‐years. The global annual recurrence, reinfection and recrudescence rate of H. pylori were 4.3% (95% CI, 4‐5), 3.1% (95% CI, 2‐5) and 2.2% (95% CI, 1‐3), respectively. The H. pylori recurrence rate was inversely related to the human development index (HDI) (ie, 3.1% 95% CI, 2‐4, 6.2% 95% CI, 4‐8 and 10.9% 95% CI, 6‐18 in countries with a very high, high and medium or low HDI) (P <.01) and directly related to H. pylori prevalence (10.9% 95% CI, 7‐16, 3.7% 95% CI, 3‐5, 3.4% 95% CI, 2‐5 and 1.6% 95% CI, 0.5‐3 in countries with a very high, high, medium or low local H. pylori prevalence) (P <.01). Global recurrence rates remained relatively stable between 1990s, 2000s and 2010s but varied across different regions (P <.05).
Conclusions
H. pylori recurrence remains a problem closely associated with socioeconomic and sanitary conditions. Methods to reduce recurrence in developing countries are needed.
Linked ContentThis article is linked to Willington and Gearry, and Roblin et al papers. To view these papers visit https://doi.org/10.1111/apt.14370 and https://doi.org/10.1111/apt.14385.
An optimized bidirectional pumping fiber amplifier is demonstrated to achieve low-frequency intensity noise suppression and effective power enhancement simultaneously. Based on the concept analysis ...of the gain saturation effect, the influence of input signal power and pump power on intensity noise suppression is investigated and optimized systematically. Further combining with the optimization of the pumping configuration to achieve the even-distribution gain, the relative intensity noise (RIN) of 1083 nm single-frequency fiber laser (SFFL) is suppressed with 9.1 dB in the frequency range below 10 kHz. Additionally, the laser power is boosted from 10.97 dBm to 25.02 dBm, and a power instability of ±0.31% is realized. This technology has contributed to simultaneously improving the power and noise performance of the 1083 nm SFFL, which can be applied to a multi-channel helium (He) optically pumping magnetometer. Furthermore, this technique has broken the mindset that power amplification of the conventional fiber amplifiers will inevitably cause the degradation of intensity noise property, and provided a valuable guidance for the development of high-performance SFFLs.
A wide variety of high-performance applications require materials for which shape control is maintained under substantial stress, and that have minimal density. Bio-inspired hexagonal and square ...honeycomb structures and lattice materials based on repeating unit cells composed of webs or trusses, when made from materials of high elastic stiffness and low density, represent some of the lightest, stiffest and strongest materials available today. Recent advances in 3D printing and automated assembly have enabled such complicated material geometries to be fabricated at low (and declining) cost. These mechanical metamaterials have properties that are a function of their mesoscale geometry as well as their constituents, leading to combinations of properties that are unobtainable in solid materials; however, a material geometry that achieves the theoretical upper bounds for isotropic elasticity and strain energy storage (the Hashin-Shtrikman upper bounds) has yet to be identified. Here we evaluate the manner in which strain energy distributes under load in a representative selection of material geometries, to identify the morphological features associated with high elastic performance. Using finite-element models, supported by analytical methods, and a heuristic optimization scheme, we identify a material geometry that achieves the Hashin-Shtrikman upper bounds on isotropic elastic stiffness. Previous work has focused on truss networks and anisotropic honeycombs, neither of which can achieve this theoretical limit. We find that stiff but well distributed networks of plates are required to transfer loads efficiently between neighbouring members. The resulting low-density mechanical metamaterials have many advantageous properties: their mesoscale geometry can facilitate large crushing strains with high energy absorption, optical bandgaps and mechanically tunable acoustic bandgaps, high thermal insulation, buoyancy, and fluid storage and transport. Our relatively simple design can be manufactured using origami-like sheet folding and bonding methods.
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