The effect of low-temperature event on the survival and growth of Juglans mandshurica seedlings within forest gaps

In forest ecosystems, gap formation changes the allocation of abiotic resources and thus affects the survival and growth of understory plants. However, how tree seedling survival and growth respond to low-temperature events and the influencing mechanisms remain unclear. To clarify how low-temperature event limits the survival and growth of tree seedlings in the montane regions of eastern Liaoning Province, northeast China, we investigated temperature and light intensity within secondary forest gaps, and the survival and growth of Juglans mandshurica seedlings after a low-temperature event in the spring of 2014. Damage to seedlings due to low temperature sig- nificantly varied in different aspects. Seedlings in gaps on southeast-facing slopes were the most seriously damaged, followed by those in gaps on northeast-facing slopes. In contrast, seedlings in west-facing gaps and in control plots without slope aspect were not damaged. The freezing injury index for seedlings was negatively correlated with minimum temperature （r = - 0.608, P 〈 0.01）, but it was positively correlated with light intensity （r= 0.818, P 〈 0.01）. In addition, height and root collar diameter of damaged seedlings were significantly lower than those of the undamaged seedlings （P 〈 0.01） during the early growing season （April-July）, but no significant difference were observed during the late growing season （July-Oc- tober） （P 〉 0.05）. The extent of seedling damage was directly related to slope aspect. Low temperature and high light intensity were found to be the dominant factors affecting extent of damage to seedlings on southeast- and northeast-facing slopes.

Response of species and stand types to snow/wind damage in a temperate secondary forest,Northeast China

Snow/wind damage is one of the important natural disturbances in forest ecosystems,especially in a montane secondary forest.However,the effects of snow/wind damage remain unclear which affects the management of these forests.Therefore,we investigated the responses of species,individual tree traits and stand structure to snow/wind damage in a montane secondary forest.Results show that,amongst the canopy trees,Betula costata exhibited the most uprooting,bending and overall damage ratio(the number of damaged stems to the total number of stems in a plot); Quercus mongolica showed the highest breakage ratio and Fraxinus mandshurica and Juglans mandshurica the least overall damage ratios.Among the subcanopy trees,Carpinus cordata,Acer mono,Acer tegmentosum and Acer pseudo-sieboldianum showed the least uprooting and breakage,and the most bending damage.A.pseudo-sieboldianum demonstrated the lowest breakage and highest bending damage ratios.Thesefindings indicate that different species have various sensitivities to snow/wind damage.Larger trees(taller,wider crowns) tend to break and become uprooted,while smaller trees are bent or remain undamaged,suggesting that tree characteristics significantly influence the types of damage from snow and wind.Stands of Q.mongolica and B.costata had the highest damage ratios,whereas A.pseudosieboldianum had the lowest snapping ratio.In summary,the severity and type of snow/wind damage are related to individual tree attributes and stand-level characteristics.Therefore,selection of suitable species(e.g.,shorter,smaller with deep root systems,hard wood,bending resistance and compression resistance) and appropriate thinning are recommended for planting in the montane secondary forests.

A pan-cancer analysis identifies SOAT1 as an immunological and prognostic biomarker

Sterol o-acyltransferase1(SOAT1)is an enzyme that regulates lipid metabolism.Nevertheless,the predictive value of SOAT1 regarding immune responses in cancer is not fully understood.Herein,we aimed to expound the predictive value and the potential biological functions of SOAT1 in pan-cancer.Raw data related to SOAT1 expression in 33 different types of cancer were acquired from The Cancer Genome Atlas(TCGA)and Genotype-Tissue Expression(GTEx)databases.SOAT1 expression was significantly increased in most cancers and showed a distinct correlation with prognosis.This enhanced expression of the SOAT1 gene was confirmed by evaluating SOAT1 protein expression using tissue microarrays.In addition,we found significant positive associations between SOAT1 expression levels and infiltrating immune cells,including T cells,neutrophils,and macrophages.Moreover,the co-expression analysis between SOAT1 and immune genes showed that many immune-related genes were increased with enhanced SOAT1 expression.A gene set enrichment analysis(GSEA)revealed that the expression of SOAT1 correlated with the tumor microenvironment,adaptive immune response,interferon signaling,and cytokine signaling.These findings indicate that SOAT1 is a potential candidate marker for predicting prognosis and a promising target for tumor immunotherapy in cancers.

Insight into the distribution of metallic elements in membrane bioreactor: Influence of operational temperature and role of extracellular polymeric substances

The distribution of metallic elements in a submerged membrane bioreactor(MBR) was revealed at different temperatures using inductively coupled plasma-optical emission spectrometry(ICP-OES), and the role of extracellular polymeric substances(EPS) was probed by integrating scanning electron microscopy(SEM) with confocal laser scanning microscopy(CLSM) over long-term operation. More metallic elements in the influent were captured by suspended sludge and built up in the fouling layer at lower temperature. The concentration of metallic elements in the effluent was 5.60 mg/L at 10°C operational temperature, far lower than that in the influent(51.35 mg/L). The total contents of metallic elements in suspended sludge and the membrane fouling layer increased to 40.20 and 52.19 mg/g at 10°C compared to 35.14 and 32.45 mg/g at 30°C, and were dominated by the organically bound fraction. The EPS contents in suspended sludge and membrane fouling layer sharply increased to 37.88 and 101.51 mg/g at 10°C, compared to 16.87 and 30.03 mg/g at 30°C. The increase in EPS content at lower temperature was responsible for the deposition of more metallic ions. The strong bridging between EPS and metallic elements at lower temperature enhanced the compactness of the fouling layer and further decreased membrane flux. This was helpful for understanding the mechanism of membrane fouling at different operational temperatures and the role of EPS, and also of significance for the design of cleaning strategies for fouled membranes after long-term operation.

Fate of proteins of waste activated sludge during thermal alkali pretreatment in terms of sludge protein recovery

Proteins are the major organic component s of waste activated sludge(WAS);the recovery of sludge proteins is economically valuable.To efficiently recover sludge proteins,WAS should undergo hydrolysis pretreatment to fully release proteins from sludge flocs and microbial cells into aqueous phase.One of the most widely used chemical methods for that is thermal alkali hydrolysis(TAH).Here,the soluble protein concentration achieved the highest level over 90 min of TAH pretreatment at 80°C;the sludge floc disintegration and microbial cell destruction were maximized according to the content profiles of bound extracellular polymeric substance(EPS)and ribonucleic acid(RNA)of sludge.Both less proteins broken down to materials with small molecular weight and less melanoidin generated were responsible.TAH pretreatment at 80°C for 90 min resulted in the solubilization of 67.59% of sludge proteins.34.64% of solubilized proteins was present in soluble high molecular;1.55% and 4.85% broke down to polypeptides and amino acids.The lost proteins via being converted to ammonium and nitrate nitrogen accounted for 9.44% of solubilized proteins.It was important to understand the fate of sludge proteins during TAH pretreatment in terms of protein recovery,which would be helpful for designing the downstream protein separation method and its potential application.

Analysis of the simultaneous adsorption mechanism of ammonium and phosphate on magnesium-modified biochar and the slow release effect of fertiliser

To decrease the eutrophication caused by nitrogen(N)and phosphorus(P)in water,magnesium-modified corn stalk biochar(MgB)was prepared under the synergistic impact of the multi-pyrolysis temperatures and Mg^(2+)contents for the co-adsorption of ammonium(NH_(4)^(+)-N)and phosphate(PO_(4)^(3−)).The co-adsorption mechanism,slow-release performance and plant application of MgB were systematically studied.The results showed that pyrolysis temperatures(350-650℃)and Mg^(2+)(0-3.6 g/L)contents not only altered the physicochemical properties of biochar,but also significantly affected the adsorption efficacy of MgB.The adsorption of NH_(4)^(+)-N and PO_(4)^(3−)was in accordance with Langmuir-Freundlich and pseudo-second-order kinetic models(Q_(max)=37.72 and 73.29 mg/g,respectively).Based on the characteristics,adsorption kinetics and isotherms results,the adsorption mechanism was determined and found to mainly involve struvite precipitation,ion exchange,and surface precipitation or electrostatic attraction.Compared with the leaching performance of chemical fertilizers(CF),after adsorption of NH_(4)^(+)-N and PO_(4)^(3−)(MgB-A),MgB had a more stable pH and lower conductivity.Leaching of NH_(4)^(+)-N and PO_(4)^(3−)by MgB-A was controlled by both the diffusion mechanism and the dissolution rate of struvite and Mg-P.The excel-lent long-term slow-release performance and abundant Mg^(2+)of MgB-A promoted the growth of Zea mays L.and Lolium perenne L.Overall,this study suggested that MgB could realize a win-win outcome of struvite biochar-based fertiliser production and wastewater treatment.

Simultaneously recovering electricity and water from wastewater by osmotic microbial fuel cells： Performance and membrane fouling

Since the concept of the osmotic microbial lhcl ceil （OsMFC） was introduced in 2011, it has attracted growing interests for its potential applications in wastewater treatment and energy recovery. However, lbrward osmosis （FO） membrane fouling resulting in a severe water flux decline remains a main obstacle. Until now, the lbuling mechanisms of FO membrane especially the development of biofouling layer in the OsMFC are not yet clear. Here, the fouling behavior of FO membrane in OsMFCs was systematically investigated. The results indicated that a thick fouling layer including biofouling and inorganic fouling was existed on the FO membrane sur｜hce. Compared to the inorganic fouling, the biofouling played a more important role in the development of the fouling layer. Further analyses by the confocal laser scanning microscopy （CLSM） implied that the growth of biofouling layer oll the FO membrane surface in the OsMFC could be divided into three stages. Initially, microorganisms associated with β-D-glucopyranose polysaccharides were deposited on the FO membrane surface. After that, the microorganisms grew into a biofilm caused a quick decrease of water flux. Subsequently, some of microorganisms were dead due to lack of nutrient source, in the meantime, polysaccharidc and proteins in the biofotiling layer werc decomposed as nutrient source, thus leading to a slow development of the biofouling layer. Moreover, the microorganisms played a significant role in the fon＇nation and development of the biotbuling layer, and further studies are needed to mitigate the deposition of microorganisms on FO membrane surfaces in OsMFCs.

Influence of aeration intensity on the performance of A/0-type sequencing batch MBR system treating azo dye wastewater

Among the numerous parameters affecting the membrane bioreactor(MBR)performance,the aeration intensity is one of the most important factors.In the present investigation,an anoxic/aerobic-type(A/O-type)sequencing batch MBR system,added anoxic process as a pretreatment to improve the biodegradability of azo dye wastewater,was investigated under different aeration intensities and the impact of the aeration intensity on effluent quantity,sludge properties,extracellular polymeric substances(EPS)amount generated as well as the change of permeation flux were examined.Neither lower nor higher aeration intensities could improve A/O-type sequencing batch MBR performances.The results showed 0.15 m^(3)·h^(-1)aeration intensity was promising for treatment of azo dye wastewater under the conditions examined.Under this aeration intensity,chemical oxygen demand(COD),ammonium nitrogen and color removal as well as membrane flux amounted to 97.8%,96.5%,98.7%and 6.21 L·m^(-2)·h^(-1),respectively.The effluent quality,with 25.0 mg·L^(-1)COD,0.84 mg·L^(-1)ammonium nitrogen and 8 chroma,could directly meet the reuse standard in China.In the meantime,the sludge relative hydrophobicity,the bound EPS,soluble EPS and EPS amounts contained in the membrane fouling layer were 70.3%,52.0 mg·g^(-1)VSS,38.8 mg·g^(-1)VSS and 90.8 mg·g^(-1)VSS,respectively,which showed close relationships to both pollutant removals and membrane flux.