"Science" (published 20220624) One -week thesis guide

Compilation | Weiyi

Science, 24 jun 2022, VOL 376, Issue 6600

"Science" June 24, 2022, Vol. 376, 6600

Chemical Chemistry

Catalyst-CONTROLLED SITE-SELECTIVE METHYLENE C-Lactonization of Dicarboxylic Acids

Catheter-controlled dilateral carboxylic acid site selective subcarmethyl C-H lactone

Author: hau Sun Sam Chan, ji-min yang, and jin -quan yu.

Link:

https://www.science.org/doi/10.1126/sclence.abq3048

Summary:

Β-and γ-subcarbonic hydrocarbon (C-H) keys in free carboxylic acid controlled by catalyst control is a long-term challenge.

The research group shows that when a pair of catalysts are assembled with a pyrine-pyridone ligands of different chewed bands, they can conduct a high-level selective monomatized response with a variety of diocar carboxylic acids. Selective β-or γ-subc -l-based C-H activation can generate γ-and Δ-lactats with diverse structures and high synthetic value.

The remaining carboxyl group is a multi -function key to further synthesize applications. The research group has achieved two natural products (Huanghua Aemisone A and PEDICELLOSINE) in the abundant di carboxylic acids, which fully proves this.

Abstract:

Catalyst-controlled site-selective activation of β- and γ-methylene carbon-hydrogen (C–H) bonds of free carboxylic acids is a long-standing challenge. Here we show that, with a pair of palladium catalysts assembled with quinoline-pyridone ligands of different chelate ring sizes, it is possible to perform highly site-selective monolactonization reactions with a wide range of dicarboxylic acids, generating structurally diverse and synthetically useful γ- and δ-lactones via site-selective β- or γ-methylene C– H activation. The remaining carboxyl group serves as a versatile linchpin for further synthetic applications, as demonstrated by the total synthesis of two natural products, myrotheciumone A and pedicellosine, from abundant dicarboxylic acids.

Earth Science Earth Science

Rapid Changes to Gebal River Suspended Sediment Flux by Humans

Human activities exacerbate the changes in the general volume of global rivers

Author: Evan N. Dethier, Carl E. RenShaw, and Francis J. Magilligan.

Link:

https://www.science.org/doi/10.1126/sclence.abn7980‍‍‍‍‍

Summary:

River supports indispensable ecological functions, human health and infrastructure. However, the limited river sampling hinders people's understanding of major changes in the river system.

Based on the estimation of the concentration and flux of the 414 major rivers and the sediments of the main rivers, the research group revealed the extensive and global changes caused by human activities in the past half century.

Dam interception in the northern hemisphere has caused the global sediments to fall to 49%before the dam. Recently, the severe changes in the use of hydrological land in the southern hemisphere have exacerbated erosion. The concentration of rivers' suspension sediments increased by 41 ± 7%compared with the 1980s.

This kind of north -south difference has quickly changed the model of the global sedimentary volume, and the main sources of suspended sediment transferred from Asia to South America.

Abstract:

Rivers support indispensable ecological functions and human health and infrastructure. Yet limited river sampling hinders our understanding of consequential changes to river systems. Satellite-based estimates of suspended sediment concentration and flux for 414 major rivers reveal widespread global change that is directly attributable to human activity in the past half-century. Sediment trapping by dams in the global hydrologic north has contributed to global sediment flux declines to 49% of pre-dam conditions. Recently, intensive land-use change in the global hydrologic south has increased erosion, with river suspended sediment concentration on average 41±7% greater than in the 1980s. This north-south divergence has rapidly reconfigured global patterns in sediment flux to the oceans, with the dominant sources of suspended sediment shifting from Asia to South America.

Global Ocean Lipidomes Show A Universal Relationship Between Tempeature and Lipid UNSATURATION

Global marine lipid body reveals the universal relationship between temperature and lipid unsaturation

Author: Henry C. Holm, Helen F. Fredricks, Shavonna M. Bent, Daniel P. Lowenstein, Justin E. Ossolinski, Kevin W. Becker, ET Al.

Link:

https://www.science.org/doi/10.1126/sclence.abn7455

Summary:

The global survey of the use of "group learning" technology has completely changed people's understanding of the ocean. Lipid groups have proven to have the potential to further understand the function of marine ecosystems, but it has not been applied globally.

The research team analyzed 930 lipid samples in the global ocean using a unified high -resolution and precise mass spectrometry, which revealed the characteristics of the unknown marine float liposuction. For 10 glycerin fats of different molecules, they identified 1151 different lipids and found that the unsaturatedness of fatty acids (ie, the number of carbon-carbon double bonds) was basically limited by temperature.

The research team predicts that in the next century, 20 -carbonic acid in essential fatty acids will drop significantly, which may have a serious harmful impact on the economically vital fisheries.

Abstract:

Global-scale surveys of plankton communities using “omics” techniques have revolutionized our understanding of the ocean. Lipidomics has demonstrated the potential to add further essential insights on ocean ecosystem function but has yet to be applied on a global scale. We analyzed 930 lipid samples across the global ocean using a uniform high-resolution accurate-mass mass spectrometry analytical workflow, revealing previously unknown characteristics of ocean planktonic lipidomes. Focusing on 10 molecularly diverse glycerolipid classes, we identified 1151 distinct lipid species, finding that fatty acid unsaturation (i.e., number of carbon-carbon double bonds) is fundamentally constrained by temperature. We predict substantial declines in the essential fatty acid eicosapentaenoic acid over the next century, which are likely to have serious deleterious effects on economically critical fisheries.8000-year doubling of Midwestern forest biomass driven by population-and biome-scale processe S

The scale of population and biological communities has doubled the biomass in the United States in the United States in 8000 years

Author: A. M. Raiho, C. J. Paciorek, A. Dawson, S. T. Jackson, D. J. Mladenoff, J. W. Williams, et al.

Link:

https://www.science.org/doi/10.1126/sclence.abk3126

Summary:

The changes in the amount of woody plant biology in several centuries to thousands of years are little known. Therefore, before the interference of the industrial era, the scale of land carbon flux is unclear.

The research team used the Bayesian model to calibrate the forest bi quantity estimation and pollen fossil records before industrialization, and to statistically rebuild the changes in forest biomass in the past 10,000 years in the United States. After the initial decline of the ice period, the biomass of the woody plant has almost doubled in the past 8000 years, and the carbon of 1800 Tai grams was sealed.

The stable accumulation of this kind of carbon is driven by ecological reactions of two different regional climate change: the expansion of forest biological communities and the population expansion of high biomass species in forests. However, the carbon exchange accumulated for thousands of years was eliminated by logging and agriculture in the industrial era in less than two centuries.

Abstract:

Changes in woody biomass over centuries to millennia are poorly known, leaving unclear the magnitude of terrestrial carbon fluxes before industrial-era disturbance. Here, we statistically reconstructed changes in woody biomass across the upper Midwestern region of the United States over the past 10,000 years using a Bayesian model calibrated to preindustrial forest biomass estimates and fossil pollen records. After an initial postglacial decline, woody biomass nearly doubled during the past 8000 years, sequestering 1800 teragrams. This steady accumulation of carbon was driven by two separate ecological responses to regionally changing climate : the spread of forested biomes and the population expansion of high-biomass tree species within forests. What took millennia to accumulate took less than two centuries to remove: Industrial-era logging and agriculture have erased this carbon accumulation.Current global efforts are insufficient to Limit warming to 1.5 ℃

The current global efforts are not enough to control the temperature rise at 1.5 ℃

Author: H. Damon Matthews and SETH WYNES

Link:

https://www.science.org/doi/10.1126/sclence.abo3378

Summary:

Human activities have led to a global warming of 1.25 ° C, and the current carbon emissions trajectory shows that the temperature will exceed 1.5 ° C in less than 10 years.

Although the growth rate of global carbon dioxide emissions has slowed down, and many countries have also strengthened emission targets, the current zero -emission targets in the middle of this century are not enough to control global warming in the range of 1.5 ° C before industrialization.

The main obstacle to achieve the 1.5 ℃ compatibility path is not the physical factors of the earth, but reflect the inertia of our political and technical system. To overcome this inertia, it is necessary to lead the leadership of politics and enterprises, as well as improving the society's understanding of the needs of the system and personal lifestyle changes.

The existing evidence has not yet shown that the world has been seriously committed to achieving the goal of 1.5 ° C in the world.

Abstract:

Human activities have caused global temperatures to increase by 1.25℃, and the current emissions trajectory suggests that we will exceed 1.5℃ in less than 10 years. Though the growth rate of global carbon dioxide emissions has slowed and many countries have strengthened their emissions targets, current midcentury net zero goals are insufficient to limit global warming to 1.5℃ above preindustrial temperatures. The primary barriers to the achievement of a 1.5℃-compatible pathway are not geophysical but rather reflect inertia in our political and technological systems. Both political and corporate leadership are needed to overcome this inertia, supported by increased societal recognition of the need for system-level and individual lifestyle changes. The available evidence does not yet indicate that the world has seriously committed to achieving the 1.5℃ goal.公共卫生Public Health

Twin Peaks: The Omicron Sars-Cov-2 BA.1 and BA.2 Epidemics in England

Double Peak: British New Crown Virus Omikon BA.1 and BA.2 popular

Author: Paul Elliott, Oliver Eles, Nicholas Steyn, David Tang, Barbara Bodinier, HAOWEI WANG, ET Al.

Link:

https://www.science.org/doi/10.1126/science.abq441111

Summary:

The rapid spread of the new crown virus Omikon variants has led to the incidence of creative records around the world.

"Real-time Evaluation-1" (React-1 "(React-1) studied using the reversal recording polymerase chain reaction (RT-PCR) to track the infection of the British SARS-COV-2, from May 2020 to March 2022, about every every way. Once a month, the 5 -year -old participants who have selected 5 -year -olds collect throat and nose swabs.

In March 2022, REACT-1 has the highest prevalence of weighted, 6.37%(a total of 109,181 participants), of which the prevalence of Omikon BA.2 variant is basically replaced by BA.1 change. body.

The prevalence is generally on the rise, of which people aged 65-74 and 75 and above have increased the greatest. This is related to the increase in the number of residents and the number of deaths, but in the context of high -level vaccine vaccination, the number is much lower than the previous waves of epidemic.

Abstract:

Rapid transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant has led to record-breaking incidence rates around the world. The Real-time Assessment of Community Transmission-1 (REACT-1) study has tracked SARS -CoV-2 infection in England using reverse transcription polymerase chain reaction (RT-PCR) results from self-administered throat and nose swabs from randomly selected participants aged 5 years and older approximately monthly from May 2020 to March 2022. Weighted prevalence in March 2022 was the highest recorded in REACT-1 at 6.37% (N = 109,181), with the Omicron BA.2 variant largely replacing the BA.1 variant. Prevalence was increasing overall, with the greatest increase in those aged 65 to 74 years and 75 Years and Older. This was associable with increased hostalizations and deflene, but at great lowers than in previous waves agingrop of high levels of Vaccination.

Capture | Guo Gang

/> />

Cooperation: [email protected]

Submission: [email protected]

Like this article? Praise + watch support!

- END -