Spatio-temporal divergence in the responses of Finland's boreal forests to climate variables

Spring greening in boreal forest ecosystems has been widely linked to increasing temperature, but few studies have attempted to unravel the relative effects of climate variables such as maximum temperature (TMX), minimum temperature (TMN), mean temperature (TMP), precipitation (PRE) and radiation (RAD) on vegetation growth at different stages of growing season. However, clarifying these effects is fundamental to better understand the relationship between vegetation and climate change. This study investigated spatio-temporal divergence in the responses of Finland's boreal forests to climate variables using the plant phenology index (PPI) calculated based on the latest Collection V006 MODIS BRDF-corrected surface reflectance products (MCD43C4) from 2002 to 2018, and identified the dominant climate variables controlling vegetation change during the growing season (May-September) on a monthly basis. Partial least squares (PLS) regression was used to quantify the response of PPI to climate variables and distinguish the separate impacts of different variables. The study results show the dominant effects of temperature on the PPI in May and June, with TMX, TMN and TMP being the most important explanatory variables for the variation of PPI depending on the location, respectively. Meanwhile, drought had an unexpectedly positive impact on vegetation in few areas. More than 50 % of the variation of PPI could be explained by climate variables for 68.5 % of the entire forest area in May and 87.7 % in June, respectively. During July to September, the PPI variance explained by climate and corresponding spatial extent rapidly decreased. Nevertheless, the RAD was found be the most important explanatory variable to July PPI in some areas. In contrast, the PPI in August and September was insensitive to climate in almost all of the regions studied. Our study gives useful insights on quantifying and identifying the relative importance of climate variables to boreal forest, which can be used to predict the possible response of forest under future warming.Peer reviewe

Enhanced CH₄ Production from Corn-Stalk Pyrolysis Using Ni-5CeO₂/MCM-41 as a Catalyst

Production of syngas from lignocellulosic biomass though pyrolysis is a promising solution for the large-scale utilization of biomass. However, current pyrolysis approaches suffer from the relative low product yield and selectivity, limiting their practical application. To solve this problem, a series of nickel-based catalysts including Ni/MCM-41, Ni-5CeO2/MCM-41, and Ni-5La2O3/MCM-41 were prepared and characterized by transmission electron microscopy (TEM), N2 adsorption–desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and H2-temperature-programmed reaction (TPR) analysis. It was observed that the simultaneous addition of Ni and CeO2 to MCM-41 could increase the reducibility of Ni and the number of active Ni0 sites on the surface of the catalyst. Consequently, Ni-5CeO2/MCM-41 gave a CH4 yield of 14.6 mmol/g, which is remarkably higher than that (10.5 mmol/g) obtained in the absence of the catalyst. Meanwhile, the CO and H2 yields increased slightly, while the CO2 yield decreased slightly. Therefore, the improved CH4 yield and selectivity was mainly due to the increased decomposition of tarry compounds catalyzed by Ni/MCM-41 with the assistance of CeO2

New Developments in Material Preparation Using a Combination of Ionic Liquids and Microwave Irradiation

During recent years, synthetic methods combining microwaves and ionic liquids became accepted as a promising methodology for various materials preparations because of their high efficiency and low energy consumption. Ionic liquids with high polarity are heated rapidly, volumetrically and simultaneously under microwave irradiation. Hence, combination of microwave irradiation as a heating source with ionic liquids with various roles (e.g., solvent, additive, template or reactant) opened a completely new technique in the last twenty years for nanomaterials and polymers preparation for applications in various materials science fields including polymer science. This review summarizes recent developments of some common materials syntheses using microwave-assisted ionic liquid method with a focus on inorganic nanomaterials, polymers, carbon-derived composites and biomass-based composites. After that, the mechanisms involved in microwave-assisted ionic-liquid (MAIL) are discussed briefly. This review also highlights the role of ionic liquids in the reaction and crucial issues that should be addressed in future research involving this synthesis technique

Zhang et al. 2018 GST reconstrcution for past four centuries

Reconstructed summer ground surface temperature for the northeast China from 1587 to 2008 (430 years)

Data from: Reconstruction of the regional summer ground surface temperature in the permafrost region of Northeast China from 1587 to 2008

To extend the historical temperature record in the permafrost region of northeast China, we reconstructed the regional ground surface temperature (GST) for the past four centuries based on a network of Dahurian larch (Larix gmelinii Rupr.) tree ring width chronologies. Seven standard tree ring chronologies, which correlated well with each other, were averaged to create a regional mean chronology. The GST was the major limiting factor for tree growth in this region. The optimum range of GSTs was from 30 May to 26 August (summer GST), identified by combining the days on which tree growth was strongly influenced by the daily GST data. The summer GST was significantly correlated with the regional mean chronology (r=0.704, p<0.001) over the common period 1971–2008 and was reconstructed for the period 1587–2008. The reconstructed GST accounted for 49.4% of the actual variance in the GST over the period 1971–2008 and captured four warm periods (1597–1603, 1716–1723, 1781–1788, and 1925–1929) and three cold periods (1639–1647, 1686–1711, and 1799–1805). The reconstructed GST was consistent with the northern hemisphere temperature in the Little Ice Age, and the warming rate from 1857 to 2008 was similar to a previously reported temperature reconstruction in the Xiao Xing’an Mountains. The low frequency of the reconstructed GST was well matched with that of the permafrost thawing depth. The reconstructed GST represents the longest temperature record in this study region and may be used as a reference for the permafrost thawing depth

Efficient Synthesis of Furfural from Biomass Using SnCl₄ as Catalyst in Ionic Liquid

Furfural is a versatile platform molecule for the synthesis of various chemicals and fuels, and it can be produced by acid-catalyzed dehydration of xylose derived from renewable biomass resources. A series of metal salts and ionic liquids were investigated to obtain the best combination of catalyst and solvent for the conversion of xylose into furfural. A furfural yield of 71.1% was obtained at high xylose loading (20 wt%) from the single-phasic reaction system whereby SnCl4 was used as catalyst and ionic liquid 1-ethyl-3-methylimidazolium bromide (EMIMBr) was used as reaction medium. Moreover, the combined catalyst consisting of 5 mol% SnCl4 and 5 mol% MgCl2 also produced a high furfural yield (68.8%), which was comparable to the furfural yield obtained with 10 mol% SnCl4. The water&#8315;organic solvent biphasic systems could improve the furfural yield compared with the single aqueous phase. Although these organic solvents could form biphasic systems with ionic liquid EMIMBr, the furfural yield decreased remarkably compared with the single EMIMBr phase. Besides, the EMIMBr/SnCl4 system with appropriate water was also efficient to convert xylan and lignocellulosic biomass corn stalk into furfural, obtaining furfural yields as high as 57.3% and 54.5%, respectively

Pretreatment of Lignocellulosic Biomass with Ionic Liquids and Ionic Liquid-Based Solvent Systems

Pretreatment is very important for the efficient production of value-added products from lignocellulosic biomass. However, traditional pretreatment methods have several disadvantages, including low efficiency and high pollution. This article gives an overview on the applications of ionic liquids (ILs) and IL-based solvent systems in the pretreatment of lignocellulosic biomass. It is divided into three parts: the first deals with the dissolution of biomass in ILs and IL-based solvent systems; the second focuses on the fractionation of biomass using ILs and IL-based solvent systems as solvents; the third emphasizes the enzymatic saccharification of biomass after pretreatment with ILs and IL-based solvent systems

Biomass Pyrolysis Technology by Catalytic Fast Pyrolysis, Catalytic Co-Pyrolysis and Microwave-Assisted Pyrolysis: A Review

With the aggravation of the energy crisis and environmental problems, biomass resource, as a renewable carbon resource, has received great attention. Catalytic fast pyrolysis (CFP) is a promising technology, which can convert solid biomass into high value liquid fuel, bio-char and syngas. Catalyst plays a vital role in the rapid pyrolysis, which can increase the yield and selectivity of aromatics and other products in bio-oil. In this paper, the traditional zeolite catalysts and metal modified zeolite catalysts used in CFP are summarized. The influence of the catalysts on the yield and selectivity of the product obtained from pyrolysis was discussed. The deactivation and regeneration of the catalyst were discussed. Catalytic co-pyrolysis (CCP) and microwave-assisted pyrolysis (MAP) are new technologies developed in traditional pyrolysis technology. CCP improves the problem of hydrogen deficiency in the biomass pyrolysis process and raises the yield and character of pyrolysis products, through the co-feeding of biomass and hydrogen-rich substances. The pyrolysis reactions of biomass and polymers (plastics and waste tires) in CCP were reviewed to obtain the influence of co-pyrolysis on composition and selectivity of pyrolysis products. The catalytic mechanism of the catalyst in CCP and the reaction path of the product are described, which is very important to improve the understanding of co-pyrolysis technology. In addition, the effects of biomass pretreatment, microwave adsorbent, catalyst and other reaction conditions on the pyrolysis products of MAP were reviewed, and the application of MAP in the preparation of high value-added biofuels, activated carbon and syngas was introduced

Biomass Pyrolysis Technology by Catalytic Fast Pyrolysis, Catalytic Co-Pyrolysis and Microwave-Assisted Pyrolysis: A Review

With the aggravation of the energy crisis and environmental problems, biomass resource, as a renewable carbon resource, has received great attention. Catalytic fast pyrolysis (CFP) is a promising technology, which can convert solid biomass into high value liquid fuel, bio-char and syngas. Catalyst plays a vital role in the rapid pyrolysis, which can increase the yield and selectivity of aromatics and other products in bio-oil. In this paper, the traditional zeolite catalysts and metal modified zeolite catalysts used in CFP are summarized. The influence of the catalysts on the yield and selectivity of the product obtained from pyrolysis was discussed. The deactivation and regeneration of the catalyst were discussed. Catalytic co-pyrolysis (CCP) and microwave-assisted pyrolysis (MAP) are new technologies developed in traditional pyrolysis technology. CCP improves the problem of hydrogen deficiency in the biomass pyrolysis process and raises the yield and character of pyrolysis products, through the co-feeding of biomass and hydrogen-rich substances. The pyrolysis reactions of biomass and polymers (plastics and waste tires) in CCP were reviewed to obtain the influence of co-pyrolysis on composition and selectivity of pyrolysis products. The catalytic mechanism of the catalyst in CCP and the reaction path of the product are described, which is very important to improve the understanding of co-pyrolysis technology. In addition, the effects of biomass pretreatment, microwave adsorbent, catalyst and other reaction conditions on the pyrolysis products of MAP were reviewed, and the application of MAP in the preparation of high value-added biofuels, activated carbon and syngas was introduced

PKCζ Phosphorylates SIRT6 to Mediate Fatty Acid β-Oxidation in Colon Cancer Cells

Protein kinase C (PKC) has critical roles in regulating lipid anabolism and catabolism. PKCζ, a member of atypical PKC family, has been reported to mediate glucose metabolism. However, whether and how PKCζ regulates tumor cells fatty acid β-oxidation are unknown. Here, we report that the phosphorylation of SIRT6 is significantly increased after palmitic acid (PA) treatment in colon cancer cells. PKCζ can physically interact with SIRT6 in vitro and in vivo, and this interaction enhances following PA treatment. Further experiments show that PKCζ is the phosphorylase of SIRT6 and phosphorylates SIRT6 at threonine 294 residue to promote SIRT6 enrichment on chromatin. In the functional study, we find that the expression of ACSL1, CPT1, CACT, and HADHB, the genes related to fatty acid β-oxidation, increases after PA stimulation. We further confirm that PKCζ mediates the binding of SIRT6 specifically to the promoters of fatty acid β-oxidation–related genes and elicits the expression of these genes through SIRT6 phosphorylation. Our findings demonstrate the mechanism of PKCζ as a new phosphorylase of SIRT6 on maintaining tumor fatty acid β-oxidation and define the new role of PKCζ in lipid homeostasis