The multiple C-H bonds of biaryl ynones render the 6-exo-trig regioselective C-H activation dearomatization to spiro5.5trienones challenging since the competing reactions of C-H bonds on Ar
or the
...-C-H bonds on Ar
may result in 5-exo-trig cyclization to indenones or 6-exo-trig
-dearomatization, respectively. We here report an unprecendented dearomatization of biaryl ynones with aldehydes via double C-H functionalization where a regiospecific remote unactivated
-C-H functionalization of biaryl ynones efficiently furnishes acylated spiro5.5trienones. This cascade cyclization features a green catalyst and solvent and high atom- and step-economy.
As a critical air pollutant, PM2.5 is proved to be associated with numerous adverse health impacts and pose serious challenges to human life. This situation is especially important for China as the ...most populous and one of the heaviest PM2.5 polluted country in the world. However, health burden estimations reported for China in previous studies may be biased due to the usage of PM2.5 concentrations at a coarsely spatial resolution, as well as the ignorance of the spatial discrepancies of parameters (e.g. respiratory rate) employed in the exposure-response function. This study therefore utilized a hybrid remote sensing-geostatistical approach to refine PM2.5 concentrations at 1 km resolution across mainland China from 2013 to 2017. Meanwhile, nationwide exposure parameters were for the first time introduced to weight the integrated exposure response (IER) function to calculate and spatially reallocate the corresponding PM2.5-attributable premature deaths at 1 km resolution. Results showed that annually averaged PM2.5 concentrations in mainland China decreased by 39.5%, from 59.1 μg/m3 in 2013 to 35.8 μg/m3 in 2017. Subsequently, PM2.5 attributable premature deaths reduced 12.6%, from 1.20 million (95% CI: 0.57; 1.71) in 2013 to 1.05 million (95% CI: 0.44; 1.44) in 2017. This declining trend was found in most parts of China except some areas in Xinjiang, Jilin, and Heilongjiang provinces. As a result, 214,821 (95% CI: 96,675; 302,897) life were saved with an estimated monetary value of US$ 210.14 billion (2011 values). However, it has to be acknowledged that, the central and northern China within priority areas of air pollution control were still experiencing high numbers of premature deaths due to the severe PM2.5 pollution and high-density population. But more worrying than these priority areas are those Harbin-Changchun Metropolitan Region, City Belt in Central Henan and Yangtze-Huaihe City Belt in non-priority areas, which also have been seriously suffering PM2.5 attributable premature deaths over 28, 000 cases per year. In conclusion, despite the huge gain in life-saving effects in China over the past five years with the help of air pollution intervention policy, future work on cleaner air and better human health is still strongly needed, especially in non-priority areas of air pollution control.
•PM2.5 related premature deaths across China at 1 km resolution were estimated.•Spatially refined premature deaths were reallocated with exposure enhanced IER model.•Clean air action over the past five years received significant health benefits.•Strategy for air pollution intervention is necessary in non-priority areas of China.
Herein we report a room temperature Fe‐catalyzed coupling reaction of various bromophenols with aryl Grignard reagents, which exhibits a wide substrate scope and high functional group tolerance. For ...the first time, the combination of simple Fe(acac)3/PBu3/Ti(OEt)4 has been used as an effective catalyst for the biaryl couplings of bromophenols or their Na or K salts with debromination and etherification side reactions being well suppressed. Various biphenols including natural product garcibiphenyl C as well as pharmaceutical diflunisal and its ethyl ester were facilely synthesized using the present protocol.
Unmanned aerial vehicles (UAVs), as emerging plant protection machinery, have the advantages of high operational efficiency, high speed, and low drift. The current study aimed to elucidate the ...characteristics of droplet distribution and drift, control efficiency on cotton aphids and spider mites, and attachment and absorption of cotton leaves during UAV spraying. Kromekote card and filter paper are used as samplers to collect droplets, and the droplet density, coverage rate, deposition, and drift percentage are statistically analyzed. The pooled results showed that the droplet uniformity, the droplet coverage rate, the deposition, and the drifting ability are higher when the UAV flight height was 2 m. The control effects by UAV spraying on cotton aphids and spider mites were 63.7% and 61.3%, respectively. These values are slightly inferior to those obtained through boom spraying. Cotton leaf attachment and absorption of spirodiclofen after UAV spraying were slightly lower than those after boom spraying, therefore, the control efficiency of cotton pests is slightly different. According to the different flight height operations by the UAV sprayer, the drift capability of the droplets at 2 m flight height was large, and the droplet uniformity and deposition were satisfactory. The research results could provide the theoretical basis and technical support for UAV operation.
Quantifying carbon dioxide (CO
2
) emissions from China’s wood and bamboo processing industry is associated with China’s emissions reduction targets, as well as mitigating global climate change. This ...study employed the Intergovernmental Panel on Climate Change Tier-2 methodology to investigate spatio-temporal evolution characteristics of carbon dioxide emission from the wood and bamboo processing industry in China from 2000 to 2019. The results showed that energy consumption reached a maximum value of 312,900.35 TJ in 2012. Energy consumption has been gradually transformed from raw coal to electricity and other clean energy. Energy intensity dropped from 1.39 TJ per million yuan of corrected production value in 2000 to 0.15 TJ per million yuan of corrected production value in 2019. Accordingly, CO
2
emissions reached their peak value of 31,148.1 thousand tons of CO
2
in 2012. Raw coal and electricity had profound impacts on CO
2
emissions. The CO
2
emission intensity declined from 140.04 tons CO
2
per million yuan of corrected production value in 2000 to 19.62 tons CO
2
per million yuan of corrected production value in 2019. We conclude that China’s wood and bamboo processing sector is a green, low-carbon industry. The spatial distribution pattern of CO
2
emissions is highly consistent with the industrial spatial layout. Furthermore, several mitigation paths were put forward.
The greenhouse gas (GHG) footprints of oriented strand boards (OSB) have been gaining growing concern. China is one of the largest manufacturers and traders of OSB in the world. However, little data ...are available concerning the GHG footprint of Chinese OSB production. The purpose of this study is to quantify and compare the GHG footprints of three types of OSB produced in China. Cradle-to-gate GHG footprints assessment models were built for OSB according to PAS 2050 guidelines. The results showed that the cradle-to-gate GHG footprints of OSB/2, OSB/3, and OSB/4 were 142.7 kg CO
2
e/m
3
, 173.2 kg CO
2
e/m
3
, and 374.2 kg CO
2
e/m
3
, respectively. Raw material acquisition was the largest contributor to GHG footprint for three types of OSB (52.6~57.6%), followed by the production process of OSB (25.6~27.3%) and transportation (15.3~20.1%). The consumption of wood, MDI, electricity, and the transportation of wood were main emission hotspots in Chinese OSB production. Ultimately, four feasible GHG emission reduction measures were put forward from the perspective of reducing the usage of wood and MDI adhesive, decreasing the electricity consumption, and shortening the transport distance of wood.
A facile arylation, alkenylation, and alkylation of functionalized 2-halopyridine N-oxides with various Grignard reagents was developed. It represented a highly efficient and selective C-H bond ...functionalization of pyridine derivatives in the presence of reactive C-Cl or C-Br bonds. Using Cl or Br as a blocking group, C2/C6 site-controllable functionalization of pyridine derivatives has been achieved. Various pyridine compounds can be prepared as illustrated in the total syntheses of Onychine, dielsine, and PARP-1 inhibitor GPI 16539.
The unprecedented substitution of a nitro group with aryl or alkenyl groups of Grignard reagents affords 2-aryl or alkenylpyridine N-oxides in modest to high yields with high chemoselectivity. This ...protocol allows a simple and clean synthesis of various 2-substituted pyridine N-oxides and the corresponding pyridine derivatives. Furthermore, straightforward one-pot iterative functionality of pyridine N-oxides could also be achieved simply by successive applications of two Grignard reagents.
Macroporous characteristics have been shown to play a key role in the osteoinductivity of hydroxyapatite ceramics, but the physics underlying the new bone formation and distribution in such scaffolds ...still remain elusive. The work here has emphasized the osteoinductive capacity of porous hydroxyapatite scaffolds containing different macroporous sizes (200–400 μm, 1200–1500 μm) and geometries (star shape, spherical shape). The assumption is that both the size and shape of a macropore structure may affect the microfluidic pathways in the scaffolds, which results in the different bone formations and distribution. Herein, a mathematical model and an animal experiment were proposed to support this hypothesis. The results showed that the porous scaffolds with the spherical macropores and large pore sizes (1200–1500 μm) had higher new bone production and more uniform new bone distribution than others. A finite element analysis suggested that the macropore shape affected the distribution of the medium–high velocity flow field, while the macropore size effected microfluid speed and the value of the shear stress in the scaffolds. Additionally, the result of scaffolds implanted into the dorsal muscle having a higher new bone mass than the abdominal cavity suggested that the mechanical load of the host tissue could play a key role in the microfluidic pathway mechanism. All these findings suggested that the osteoinduction of these scaffolds depends on both the microfluid velocity and shear stress generated by the macropore size and shape. This study, therefore, provides new insights into the inherent osteoinductive mechanisms of bioceramics, and may offer clues toward a rational design of bioceramic scaffolds with improved osteoinductivity.
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•Four new dammarane-type saponins isolated from G. pentaphyllum.•They showed low cytotoxicities against A549 cells, HepG2 cells and SH-SY5Y cells.•They appeared protective effects ...against hydrogen peroxide induced SH-SY5Y cell death.
Gynostemma pentaphyllum has been used as a medicine-food homologious health product in China for a long time. This research aimed to isolate and identify its active compounds with protective effects against hydrogen peroxide induced SH-SY5Y cell death. Four new dammarane-type saponins were isolated from G. pentaphyllum using various chromatographic methods. They were identified as gypenoside S1 (1), gypenoside S3 (2), gypenoside S2 (3) and gypenoside S4 (4), respectively by HRESIMS and NMR spectra. Their cytotoxic activity was evaluated against three human cancer cell lines, A549 (lung), HepG2 (liver), SH-SY5Y (nerve), by MTT method. They showed low cytotoxicities with the IC50 values of more than 100 μM on three cancer cell lines. However, they appeared protective effects against hydrogen peroxide induced SH-SY5Y cell death in a dose-dependent manner. They recovered cell viability more than 69% at the concentration of 20 μM from 66%, while as vitamin C to 67%. Compound 3 and 4 recovered more than 79% at 100 μM. The present study suggests that G. pentaphyllum has antioxidative potential and the saponins from G. pentaphyllum are considered as the active compounds with safe and neuroprotecitve effect.
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