Many pharmaceutically relevant molecules are still extracted directly from lignocellulosic biomass sources. As this can be a bottleneck in supply, total quantification followed by total extraction are desirable processes to ensure as much as possible is obtained, at the optimal time in the growth cycle. Herein we report the application of solid-state 13C nuclear magnetic resonance (NMR) spectroscopy to quantify shikimic acid present inside Chinese star anise (or star aniseed, llicium verum). Subsequently, methanol soxhlet extraction is compared with conventional aqueous hydroxides (i.e. sodium hydroxide) and cellulose-dissolving aqueous hydroxides (i.e. tetraethylammonium and tetrabutylammonium hydroxide) for shikimic acid isolation. Methanol extraction isolated ca. 6.6±0.1 wt% (wt%) shikimic acid (post-purification), and solid-state NMR confirmed extraction was incomplete even after 72 h. Conversely, dissolution of the star anise at room temperature in tetrabutylammonium hydroxide ([N4444]OH) allowed isolation of ca. 14.0±0.6 wt% shikimic acid (post-purification). Solid state NMR confirmed the star anise initially contained 19±3 wt% shikimic acid, which was quantitatively extracted after dissolution in the aqueous hydroxide solution. The solubility of the star anise and the kinetics of the shikimic acid extraction were also briefly evaluated. 相似文献
The present study represents a challenging effort aiming at converting the waste algal biomass Ulva sp. into a source of high added value materials for biomedical applications by means of a clean and sustainable process. Ulvan, a sulphated polysaccharide extracted from Ulva sp., is investigated as in situ gelling material by using the enzyme horseradish peroxidase as catalyst and H2O2 as reagent. The polysaccharide is successfully modified with tyramine units in order to be susceptible to enzymatic recognition and crosslinking through oxidative coupling. The times of gelation of ulvan‐tyramine solutions are optimized by adjusting the amount of H2O2 used for ensuring their practical administration as injectable systems. The rheological properties of the polymeric solutions and the relevant hydrogels evaluated under operative conditions prove to be suitable as injectable in situ forming 3D‐hydrogels. The preliminary biological assays evidence the full cytocompatibility of the developed hydrogels and their feasibility for being used as 3D‐hydrogels for cell delivery.
Ozone is the third most important anthropogenic greenhouse gas after carbon dioxide and methane but has a larger uncertainty in its radiative forcing, in part because of uncertainty in the source characteristics of ozone precursors, nitrogen oxides, and volatile organic carbon that directly affect ozone formation chemistry. Tropospheric ozone also negatively affects human and ecosystem health. Biomass burning (BB) and urban emissions are significant but uncertain sources of ozone precursors. Here, we report global-scale, in situ airborne measurements of ozone and precursor source tracers from the NASA Atmospheric Tomography mission. Measurements from the remote troposphere showed that tropospheric ozone is regularly enhanced above background in polluted air masses in all regions of the globe. Ozone enhancements in air with high BB and urban emission tracers (2.1 to 23.8 ppbv [parts per billion by volume]) were generally similar to those in BB-influenced air (2.2 to 21.0 ppbv) but larger than those in urban-influenced air (−7.7 to 6.9 ppbv). Ozone attributed to BB was 2 to 10 times higher than that from urban sources in the Southern Hemisphere and the tropical Atlantic and roughly equal to that from urban sources in the Northern Hemisphere and the tropical Pacific. Three independent global chemical transport models systematically underpredict the observed influence of BB on tropospheric ozone. Potential reasons include uncertainties in modeled BB injection heights and emission inventories, export efficiency of BB emissions to the free troposphere, and chemical mechanisms of ozone production in smoke. Accurately accounting for intermittent but large and widespread BB emissions is required to understand the global tropospheric ozone burden.Tropospheric ozone (O3) has been the focus of decades of scientific research due to its central role in atmospheric chemistry (1), its adverse impact on human and ecosystem health (2, 3), and its role as a climate forcer (4, 5). Despite this focus, there remains considerable uncertainty in tropospheric O3 production pathways, precursor sources, and long-term trends. Sources of tropospheric O3 include downward transport from the stratosphere and photochemical production from a complex set of coupled reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs), each of which is in turn emitted from both anthropogenic and natural sources (1, 6). The contribution of fossil fuel combustion to tropospheric O3 has recently declined in the United States and in Europe, proportionally increasing the contribution from natural sources (7–10). However, the spatial distribution of anthropogenic O3 precursor emissions have shifted to lower latitudes (11, 12), where they are still increasing (13). Additionally, globally averaged tropospheric O3 has increased over the past five decades (14, 15). Understanding the sources of tropospheric O3 is thus essential to explain this trend and to inform the development of effective mitigation strategies from regional to hemispheric scales.Biomass burning (BB) is an important source of O3 precursors (16–19). A recent study based on observed O3 to carbon monoxide (CO) enhancements in smoke plumes attributed 3.5% of the global tropospheric chemical O3 production to BB emissions (19). Other studies have accounted for the numerous production and destruction pathways of O3 in the troposphere using global chemical transport models (CTMs) to estimate the global budget of O3 (20, 21). However, few studies separately quantify the contributions of fossil fuel combustion and BB emissions to global tropospheric O3 (22). Global inventories attribute five times more NOx (23, 24) but roughly equal VOC emissions (17, 25) to fossil fuel combustion (hereafter referred to as urban sources) compared with BB. However, precursor emissions do not necessarily determine tropospheric O3 production close to the sources because of the nonlinearity of O3 formation chemistry (26, 27). Additionally, global CTMs do not always agree on the tropospheric O3 burden, suggesting possible deficiencies with emission inventories of O3 precursors and/or an incomplete representation of O3 chemistry (21, 28–30), although a recent model intercomparison study showed that the model ensemble reproduced well the salient spatial, seasonal, and decadal variability and trends of tropospheric O3 (31).Large-scale in situ observational constraints commensurate with the grid resolution of current global CTMs are rare. Instead, modeling studies often rely on ozonesonde-derived climatologies and satellite-based remote sensing observations to constrain tropospheric O3 distributions and precursor sources (20, 32, 33). The recent NASA Atmospheric Tomography (ATom) mission provides global-scale and seasonally resolved in situ measurements of O3 and CO and a comprehensive suite of trace gases and aerosol parameters, including tracers of BB and urban emissions (34). ATom sampled the remote troposphere from the Arctic to the Antarctic over the Pacific and Atlantic Oceans using repeated vertical profiles from ∼0.2 to ∼13 km in altitude during four seasonal deployments between 2016 and 2018 (Fig. 1). Recently, the ubiquitous presence of dilute BB smoke in the remote troposphere and its significant contribution to aerosol mass loading was established using ATom observations (35). Here, we use ATom measurements to quantify the individual contributions of urban and BB emissions to O3 in the remote global troposphere using tracers specific to each source. We compare this analysis with simulations from three global CTMs that alternatively set BB and urban emissions to zero to evaluate their impact on modeled tropospheric O3.Open in a separate windowFig. 1.Map of ATom flight tracks from the four seasonal global circuits colored by tropospheric O3 mixing ratios. Note that the color scale terminates at 70 ppbv of O3, and higher values are shown in red. Measurements with a strong stratospheric influence were parsed out as indicated in Materials and Methods. 相似文献
In this study, soy waste biomass (SW) resulting from oil extraction was treated with alkaline solution, and the obtained material (Na-SW) was used as biosorbent for the removal of Pb(II), Cd(II), and Zn(II) ions from aqueous media. The performance of this biosorbent was examined in batch systems, at different initial metal ion concentrations and contact times (pH 3.4; 5 g of biosorbent/L). Isotherm and kinetic modeling was used to calculate the equilibrium and kinetics of the biosorption processes. The maximum biosorption capacity, calculated from the Langmuir isotherm model, followed the order Zn(II) (0.49 mmol/g) > Cd(II) (0.41 mmol/g) ≈ Pb(II) (0.40 mmol/g), while the kinetics of biosorption processes fit the pseudo-second-order model. Three cycles of biosorption/desorption were performed to estimate the reusability of Na-SW biosorbent, and the regeneration efficiency was higher than 97% in all cases. The practical applicability of Na-SW biosorbent in treating of wastewater contaminated with Pb(II), Cd(II), and Zn(II) ions was examined using simulated wastewater samples, and the main quality characteristics of the effluents obtained after treatment were evaluated. All these aspects highlight the potential applicability of Na-SW for large-scale wastewater treatment. 相似文献
Both fibrosing mediastinitis (FM) and bronchial anthracofibrosis (BAF) are unique diseases. The combined appearance of FM and BAF is extremely rare.
Objectives
The aim of this study was to investigate the clinical features of patients with coexisting FM and BAF.
Method
Between January 2003 and December 2015, a total of eight patients were diagnosed at the Peking Union Medical College Hospital as having combined FM and BAF. The clinical presentations, radiographic features and bronchoscopic findings of the eight patients were reviewed.
Results
The patients were five women and three men with a median age of 64 years (range 56‐86 years). Symptoms included dyspnea (eight patients), cough (seven patients), chest pain (two patients), hemoptysis (two patients) and so on. Chest CT of all eight patients showed mediastinal soft‐tissue lesions, with multiple narrowed or obliterated lobar or segmental bronchi and arteries. Bronchoscopy showed that all of the patients had multiple stenoses of lobar or segmental bronchi with anthracotic pigmentation on the mucosa. Echocardiography showed that all of the patients had elevated pulmonary arterial systolic pressure (median 81 mm Hg, range 51‐107 mm Hg). Each of the eight patients had a history of exposure to, or infection with, tuberculosis, although there was no evidence of active disease. All of the eight patients had long‐term exposure to indoor coal or biomass fuel smoke.
Conclusions
FM can coexist with BAF, characterized by prominent pulmonary hypertension. The possible etiological factors are tuberculosis and coal or biomass fuel exposure. 相似文献