Contrasting effects of maize residue,coal gas residue and their biochars on nutrient mineralization,enzyme activities and CO2 emissions in sandy loess soil

Mismanagement of crop straw and coal gas residue threatens the atmosphere and the economy. Nevertheless, thermal-pyrolysis is an option for management that turns bio-waste into biochar; its viability and adoption by the public as soil amendments is dependent on the agronomic and environmental values compared between biochar and the raw materials. We undertook a 60-day short-term analysis to assess the impact of various wastes and biochars, as well as inorganic nutrients (N), on carbon dioxide (CO₂) fluxes, soil enzyme activities, soil fertility status, and microbial activities. There were eight treatments of soil amendments: without an amendment (CK), Nutrients (N), straw + nutrients (S+N), straw biochar + nutrients (SB+N), coal gas residue + nutrients (C+N), coal gas residue biochar + nutrients (CB+N), straw + straw biochar + nutrients (S+SB+N) and coal gas residue waste + coal gas residue biochar + nutrients (C+ CB +N). The results indicated that soil EC, pH, nitrate N (NO₃^–- N), SOC, TN and available K were significantly (p < 0.05) increased coal gas residue biochar and combined with coal fly ash as compared to maize straw biochar and combined with maize straw and N treatments. The higher concentrations of soil MBC and MBN activities were increased in the maize straw application, while higher soil enzyme activity such as, invertase, urease and catalase were enhanced in the coal fly ash derived biochar treatments. The higher cumulative CO₂ emissions were recorded in the combined applications of maize straw and its biochar as well as coal gas residue and its biochar treatment. Our study concludes, that maize straw and coal fly ash wastes were converted into biochar product could be a feasible substitute way of discarding, since land amendment and decreased CO₂ fluxes and positive changes in soil microbial, and chemical properties, and can be confirmed under long-term conditions for reduction of economical and environment issues.     

Phosphorus-Assisted Biomass Thermal Conversion: Reducing Carbon Loss and Improving Biochar Stability

There is often over 50% carbon loss during the thermal conversion of biomass into biochar, leading to it controversy for the biochar formation as a carbon sequestration strategy. Sometimes the biochar also seems not to be stable enough due to physical, chemical, and biological reactions in soils. In this study, three phosphorus-bearing materials, H₃PO₄, phosphate rock tailing (PRT), and triple superphosphate (TSP), were used as additives to wheat straw with a ratio of 1: 0.4–0.8 for biochar production at 500°C, aiming to alleviate carbon loss during pyrolysis and to increase biochar-C stabilization. All these additives remarkably increased the biochar yield from 31.7% (unmodified biochar) to 46.9%–56.9% (modified biochars). Carbon loss during pyrolysis was reduced from 51.7% to 35.5%–47.7%. Thermogravimetric analysis curves showed that the additives had no effect on thermal stability of biochar but did enhance its oxidative stability. Microbial mineralization was obviously reduced in the modified biochar, especially in the TSP-BC, in which the total CO₂ emission during 60-d incubation was reduced by 67.8%, compared to the unmodified biochar. Enhancement of carbon retention and biochar stability was probably due to the formation of meta-phosphate or C-O-PO₃, which could either form a physical layer to hinder the contact of C with O₂ and bacteria, or occupy the active sites of the C band. Our results indicate that pre-treating biomass with phosphors-bearing materials is effective for reducing carbon loss during pyrolysis and for increasing biochar stabilization, which provides a novel method by which biochar can be designed to improve the carbon sequestration capacity.     

Confined Fe2VO4⊂Nitrogen‐Doped Carbon Nanowires with Internal Void Space for High‐Rate and Ultrastable Potassium‐Ion Storage

Developing low‐cost, high‐capacity, high‐rate, and robust earth‐abundant electrode materials for energy storage is critical for the practical and scalable application of advanced battery technologies. Herein, the first example of synthesizing 1D peapod‐like bimetallic Fe₂VO₄ nanorods confined in N‐doped carbon porous nanowires with internal void space (Fe₂VO₄?NC nanopeapods) as a high‐capacity and stable anode material for potassium‐ion batteries (KIBs) is reported. The peapod‐like Fe₂VO₄?NC nanopeapod heterostructures with interior void space and external carbon shell efficiently prevent the aggregation of the active materials, facilitate fast transportation of electrons and ions, and accommodate volume variation during the cycling process, which substantially boosts the rate and cycling performance of Fe₂VO₄. The Fe₂VO₄?NC electrode exhibits high reversible specific depotassiation capacity of 380 mAh g^?1 at 100 mA g^?1 after 60 cycles and remarkable rate capability as well as long cycling stability with a high capacity of 196 mAh g^?1 at 4 A g^?1 after 2300 cycles. The first‐principles calculations reveal that Fe₂VO₄?NC nanopeapods have high ionic/electronic conductivity characteristics and low diffusion barriers for K⁺‐intercalation. This study opens up new way for investigating high‐capacity metal oxide as high‐rate and robust electrode materials for KIBs.     

Iron‐Based Supercapacitor Electrodes: Advances and Challenges

Supercapacitors (SCs) have great promise as the state‐of‐the‐art power source in portable electronics and hybrid vehicles. The performance of SCs is largely determined by the properties of the electrode material, and numerous efforts have been devoted to the explorations of novel electrode materials. Recently, iron‐based materials, including Fe₂O₃, Fe₃O₄, FeOOH, FeO_x, CoFe₂O₄, and MnFe₂O₄, have received considerable attention as very promising electrode materials for SCs due to their high theoretical specific capacitances, natural abundance, low cost, and non‐toxicity. However, most of these Fe‐based SC electrodes suffer from poor conductivity and/or electrochemical instability, which seriously impede their implementation as high‐performance electrodes for SCs. To settle these issues, substantial efforts have been made in improving their conductivity and cycling stability, and great processes have been achieved. Here, recent research advances in the rational design and synthesis of diverse Fe‐based nanostructured electrodes and their capacitive performance for SCs are presented. Besides, challenges and prospects of Fe‐based materials as advanced negative electrodes for SCs are also discussed.     

Unveiling Chemically Robust Bimetallic Squarate-Based Metal–Organic Frameworks for Electrocatalytic Oxygen Evolution Reaction

Here, this work reports an innovative strategy for the synthesis of chemically robust metal–organic frameworks (MOFs), and applies them as catalysts for the electrocatalytic oxygen evolution reaction (OER). A bimetallic squarate-based MOF (Sq-MOF) with a zbr topology serves as an excellent platform for electrocatalytic OER owing to its open porous structure, high affinity toward water, and presence of catalytically active 1D metal hydroxide strips. By regulating the Ni²⁺ content in a bimetallic squarate MOF system, the electrochemical structural stability toward OER can be improved. The screening of various metal ratios demonstrates that Ni₃Fe₁ and Ni₂Fe₁ Sq- zbr -MOFs show the best performance for electrocatalytic OER in terms of catalytic activity and structural stability. Ni₂Fe₁ Sq- zbr -MOF shows a low overpotential of 230 mV (at 10 mA cm⁻²) and a small Tafel slope of 37.7 mV dec⁻¹, with an excellent long-term electrochemical stability for the OER. Remarkably, these overpotential values of Ni₂Fe₁ Sq- zbr -MOF are comparable with those of the best-performing layered double hydroxide (LDH) systems and outperforms the commercially available noble-metal-based RuO₂ catalyst for OER under identical operational conditions.     

2016生物基材料专刊序言

生物基材料,是利用谷物、豆科、秸秆、竹木粉等可再生生物质为原料制造的新型材料和化学品等,包括生物合成、生物加工、生物炼制过程获得的生物醇、有机酸、烷烃、烯烃等基础生物基化学品,也包括生物基塑料、生物基纤维、糖工程产品、生物基橡胶以及生物质热塑性加工得到塑料材料等。生物基材料由于其绿色、环境友好、资源节约等特点,正逐步成为引领当代世界科技创新和经济发展的又一个新的主导产业。本期专刊报道了生物基材料总体发展情况,介绍了生物基纤维、聚羟基烷酸酯、可生物降解地膜、生物基聚酰胺、蛋白医用生物材料、生物基聚氨酯、聚乳酸改性与加工等几个方面行业状况及其研究进展。     

Comparative evaluation for the sorption capacity of four carbonaceous sorbents to phenol

Sorption kinetics and isotherms of phenol by four carbonaceous sorbents (activated carbon (AC), mesoporous carbon (MPC), bamboo biochar (BBC) and oak wood biochar (OBC)) were compared in this study. MPC has the fastest sorption rate and initial sorption potential, which were indicated by sorption rate constants and initial sorption rate “h” in a pseudo-second-order kinetic model. The ordered and straight pore structure of MPC facilitated the accessibility of phenol. The AC showed the greatest sorption capacity towards phenol with maximum sorption of 123 mg/g as calculated by the Langmuir model. High surface area, complexity of pore structure, and the strong binding force of the π–π electron-donor-acceptor interaction between phenol molecules and AC were the main mechanisms. The BBC and OBC had much slower sorption and lower sorption capacity (33.04 and 29.86 mg/g, respectively), compared to MPC (73.00 mg/g) and AC, indicating an ineffective potential for phenol removal from water.     

Study of the cytotoxicity and particle action in human cancer cells of titanocene-functionalized materials with potential application against tumors

Titanocene dichloride [Ti(η⁵-C₅H₅)₂Cl₂] (1), has been grafted onto dehydrated hydroxyapatite (HAP), Al₂O₃ and two mesoporous silicas MSU-2 (Michigan State University Silica type 2) and HMS (Hexagonal Mesoporous Silica), to give the novel materials HAP/[Ti(η⁵-C₅H₅)₂Cl₂] (S1) (1.01 wt.% Ti), Al₂O₃/[Ti(η⁵-C₅H₅)₂Cl₂] (S2) (2.36 wt.% Ti), HMS/[Ti(η⁵-C₅H₅)₂Cl₂] (S3) (0.75 wt.% Ti) and MSU-2/[Ti(η⁵-C₅H₅)₂Cl₂] (S4) (0.74 wt.% Ti), which have been characterized by powder X-ray diffraction, X-ray fluorescence, nitrogen gas sorption, multinuclear magic angle spinning NMR spectroscopy, IR spectroscopy, thermogravimetry analysis, UV spectroscopy, scanning electronic microscopy and transmission electronic microscopy. The cytotoxicity of the titanocene-functionalized materials toward human cancer cell lines from five different histogenic origins: 8505 C (anaplastic thyroid cancer), A253 (head and neck cancer), A549 (lung carcinoma), A2780 (ovarian cancer) and DLD-1 (colon cancer) has been determined. M₅₀ values (quantity of material needed to inhibit normal cell growth by 50%) and Ti-M₅₀ values (quantity of anchored titanium needed to inhibit normal cell growth by 50%) indicate that the activity of S1-S4 against studied human cancer cells depended on the surface type as well as on the cell line. In addition, studies on the titanocene release and the interaction of the materials S1-S4 with DNA show that the cytotoxic activity may be due to particle action, because no release of titanium complexes has been observed in physiological conditions, while electrostatic interactions of titanocene-functionalized particles with DNA have been observed.     

Development of electrochemical sulfite biosensor based on SOX/PBNPs/PPY modified Au electrode

A sulfite oxidase (SO_X) (EC 1.8.3.1) purified from Syzygium cumini leaves was immobilized onto Prussian blue nanoparticles/polypyrrole (PBNPs/PPY) nanocomposite film electrodeposited onto the surface of gold (Au) electrode. An electrochemical sulfite biosensor was fabricated using SO_X/PBNPs/PPY/Au electrode as working electrode, Ag/AgCl as standard electrode and Pt wire as auxiliary electrode connected through a potentiostat. The working electrode was characterized by Fourier Transform infrared (FTIR) spectroscopy, cyclic voltammetry (CV), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) at different stages of its construction. The biosensor showed optimum response within 2 s, when operated at 20 mV s⁻¹ in 0.1 M Tris–HCl buffer, pH 8.0 and at 30 °C. Linear range and minimum detection limit were 0.5–1000 μM and 0.1 μM (S/N = 3) respectively. The sensor was evaluated with 95.0% recovery of added sulfite in red wine samples and 1.9% and 3.3% within and between batch coefficients of variation respectively. There was a good correlation (r = 0.96) between red wine samples sulfite value by standard DTNB method and the present method. The sensor was employed for determination of sulfite level in red, white and rose wine samples. The enzyme electrode was used 300 times over a period of 4 months, when stored at 4 °C.     

Biochar application as a tool to decrease soil nitrogen losses (NH3 volatilization,N2O emissions,and N leaching) from croplands: Options and mitigation strength in a global perspective

Biochar application to croplands has been proposed as a potential strategy to decrease losses of soil‐reactive nitrogen (N) to the air and water. However, the extent and spatial variability of biochar function at the global level are still unclear. Using Random Forest regression modelling of machine learning based on data compiled from the literature, we mapped the impacts of different biochar types (derived from wood, straw, or manure), and their interactions with biochar application rates, soil properties, and environmental factors, on soil N losses (NH₃ volatilization, N₂O emissions, and N leaching) and crop productivity. The results show that a suitable distribution of biochar across global croplands (i.e., one application of <40 t ha^?1 wood biochar for poorly buffered soils, such as those characterized by soil pH<5, organic carbon<1%, or clay>30%; and one application of <80 t ha^?1 wood biochar, <40 t ha^?1 straw biochar, or <10 t ha^?1 manure biochar for other soils) could achieve an increase in global crop yields by 222–766 Tg yr^?1 (4%–16% increase), a mitigation of cropland N₂O emissions by 0.19–0.88 Tg N yr^?1 (6%–30% decrease), a decline of cropland N leaching by 3.9–9.2 Tg N yr^?1 (12%–29% decrease), but also a fluctuation of cropland NH₃ volatilization by ?1.9–4.7 Tg N yr^?1 (?12%–31% change). The decreased sum of the three major reactive N losses amount to 1.7–9.4 Tg N yr^?1, which corresponds to 3%–14% of the global cropland total N loss. Biochar generally has a larger potential for decreasing soil N losses but with less benefits to crop production in temperate regions than in tropical regions.     

Elevated CO2 concentration enhances the role of the ear to the flag leaf in determining grain yield of wheat

Net photosynthetic rate (P _N) of ear and flag leaf during grain filling stage and grain yield of plants with non-darkened or darkened flag leaf or darkened ear were examined in two different CO₂ concentrations: ambient (AC) and AC+200 μmol mol⁻¹ (EC). Ear showed much higher enhancement (56 %) of P _N than flag leaf (23 %) under EC. Moreover, CO₂ enrichment shortened the photosynthetic duration of flag leaf relative to ear. In this way the ratio of ear to flag leaf contribution to grain yield increased from 1.18 (AC) to 1.39 (EC).     

Rational Construction of Self‐Standing Sulfur‐Doped Fe2O3 Anodes with Promoted Energy Storage Capability for Wearable Aqueous Rechargeable NiCo‐Fe Batteries

Aqueous rechargeable Ni‐Fe batteries featuring an ultra‐flat discharge plateau, low cost, and outstanding safety characteristics show promising prospects for application in wearable energy storage. In particular, fiber‐shaped Ni‐Fe batteries will enable textile‐based energy supply for wearable electronics. However, the development of fiber‐shaped Ni‐Fe batteries is currently challenged by the performance of fibrous Fe‐based anode materials. In this context, this study describes the fabrication of sulfur‐doped Fe₂O₃ nanowire arrays (S‐Fe₂O₃ NWAs) grown on carbon nanotube fibers (CNTFs) as an innovative anode material (S‐Fe₂O₃ NWAs/CNTF). Encouragingly, first‐principle calculations reveal that S‐doping in Fe₂O₃ can dramatically reduce the band gap from 2.34 to 1.18 eV and thus enhance electronic conductivity. The novel developed S‐Fe₂O₃ NWAs/CNTF electrode is further demonstrated to deliver a very high capacity of 0.81 mAh cm^?2 at 4 mA cm^?2. This value is almost sixfold higher than that of the pristine Fe₂O₃ NWAs/CNTF electrode. When a cathode containing zinc‐nickel‐cobalt oxide (ZNCO)@Ni(OH)₂ NWAs heterostructures is used, 0.46 mAh cm^?2 capacity and 67.32 mWh cm^?3 energy density are obtained for quasi‐solid‐state fiber‐shaped NiCo‐Fe batteries, which outperform most state‐of‐the‐art fiber‐shaped aqueous rechargeable batteries. These findings offer an innovative and feasible route to design high‐performance Fe‐based anodes and may inspire new development for the next‐generation wearable Ni‐Fe batteries.     

Electrolytes toward High‐Voltage Na3V2(PO4)2F3 Positive Electrode Durable against Temperature Variation

High power and energy density, long cyclability, and tolerance for wide temperature (seasonal and daily operational temperature differences) must be considered to construct large‐scale sodium secondary batteries. In this regard, Na₃V₂(PO₄)₂F₃ (NVPF) has become a subject of interest as a high‐performance positive electrode material owing to its high energy density. However, the high operating voltage of NVPF causes continuous decomposition of electrolytes during cycles, resulting in significant capacity fading and low Coulombic efficiency. In this study, the electrochemical performance of the NVPF electrode in organic solvent electrolytes with and without additives and an ionic liquid is investigated at high voltage regimes over a wide temperature range (?20 °C to 90 °C). The results reveal that the performance of organic electrolytes is still insufficient even with additives, and the ionic liquid electrolyte demonstrates high electrochemical stability and cyclability with NVPF electrodes over a temperature range from ?20 °C to 90 °C, achieving stable cycling over 500 cycles. The detailed electrochemical analysis combined with X‐ray photoelectron and energy dispersive X‐ray spectroscopy indicates that a sturdy cathode electrolyte interphase layer around the electrode protects it from capacity fading at high voltage and elevated temperature, resulting in high Coulombic efficiency.     

An Effective Lithium Sulfide Encapsulation Strategy for Stable Lithium–Sulfur Batteries

With a high theoretical capacity of 1162 mA h g^?1, Li₂S is a promising cathode that can couple with silicon, tin, or graphite anodes for next‐generation energy storage devices. Unfortunately, Li₂S is highly insulating, exhibits large charge overpotential, and suffers from active‐material loss as soluble polysulfides during battery cycling. To date, low‐cost, scalable synthesis of an electrochemically active Li₂S cathode remains a challenge. This work demonstrates that the low conductivity and material loss issues associated with Li₂S cathodes can be overcome by forming a stable, conductive encapsulation layer at the surface of the Li₂S bulk particles through in situ surface reactions between Li₂S and electrolyte additives containing transition‐metal salts. It is identified that the electronic band structure in the valence band region of the thus‐generated encapsulation layers, consisting largely of transition‐metal sulfides, determines the initial charging resistance of Li₂S. Furthermore, among the transition metals tested, the encapsulation layer formed with an addition of 10 wt% manganese (II) acetylacetonate salt proved to be robust within the cycling window, which is attributed to the chemically generated MnS surface species. This work provides an effective strategy to use micrometer‐sized Li₂S directly as a cathode material and opens up new prospects to tune the surface properties of electrode materials for energy‐storage applications.     

Short-term effects of 3,4-methylen-dioxy-metamphetamine (MDMA) on 5-HT1A receptors in the rat hippocampus

The first effects of 3,4-methylen-dioxy-metamphetamine (MDMA, “ecstasy”), on serotonin 1A (5-HT_1A) receptors in rat hippocampus were determined by means of [³H]-8-hydroxy-dipropylamino-tetralin ([³H]-8-OH-DPAT) and 5′guanosine-(γ-[³⁵S]-thio)triphosphate ([³⁵S]-GTPγS) binding as well as inhibition of forskolin (FK)-stimulated adenylyl cyclase (AC) activity. The study was completed by [³⁵S]-GTPγS functional autoradiography experiments carried out in frontal sections of rat brain, including the hippocampal region. Results showed that MDMA was either able to displace [³H]-8-OH-DPAT binding (K_i ≅ 500 nM) or to reduce the number of specific sites (B_max) without affecting K_d. The drug also failed to change the [³⁵S]-GTPγS binding or to inhibit AC velocity, underlying its behavior as a non-competitive 5-HT_1A receptor antagonist. Further, MDMA (1 or 100 μM), partially antagonized either [³⁵S]-GTPγS binding stimulation of the agonists 5CT and 8-OH-DPAT or the AC inhibition induced by 5CT and DP-5CT. However, in contrast to binding studies, in AC assays the amphetamine displayed an effect also on EC₅₀, always being less potent than the reference antagonist WAY100,635. In functional autoradiography, MDMA behaved either as a partial 5-HT_1A antagonist in limbic areas or, added alone, as an agonist, increasing the coupling signal presumably through 5-HT release from synapses. Interestingly, the selective 5-HT re-uptake inhibitor (SSRI) fluoxetine had no effect on MDMA [³⁵S]-GTPγS binding activation. This latter finding indicates that the amphetamine can release 5-HT via alternative mechanisms to 5-HT transporter binding, probably via membrane synaptic receptors or vesicular transporters. The release of other transmitters is not excluded. Therefore, our results encourage at extending the study of MDMA biochemical profiles, in the attempt to elucidate those amphetamine-induced pathways with a potential for neurotoxicity or psycho-stimulant activity.     

Lipophilic polyoxomolybdate nanocapsules in constitutional dynamic hybrid materials

Dynamic hybrid materials based on Müller’s porous Keplerate type molybdenum-oxide based nanocapsules are described. The present efforts involve the preparation and properties of hybrid materials formed between lipophilic MCM41-mesoporous or octadecyldimethylsilica with Keplerate type molybdenum-oxide based Mo132 nanocapsules - designed by encapsulation into DODA - dimethyldioctadecylammonium cationic surfactants (DODA)₄₀Mo132. In particular, the use of a “dynamic reversible hydrophobic interface” between (DODA)₄₀Mo132 and lipophilic silica can render the emerging hybrid mesophases self-adaptive. The reversible hydrophobic interactions allow to both capsule and inorganic silica components to mutually (synergistically) adapt their spatial constitution during simultaneous (collective) formation of self-organized hybrid domains. This might provide new insights into the features that control the design of novel complex materials.     

Effect of catalyst additives on the production of biofuels from palm oil cracking in a transport riser reactor

Catalytic cracking of crude palm oil (CPO) and used palm oil (UPO) were studied in a transport riser reactor for the production of biofuels at a reaction temperature of 450 °C, with residence time of 20 s and catalyst-to-oil ratio (CTO) of 5 g g^?1. The effect of HZSM-5 (differrent Si/Al ratios), beta zeolite, SBA-15 and AlSBA-15 were studied as physically mixed additives with cracking catalyst Rare earth-Y (REY). REY catalyst alone gave 75.8 wt% conversion with 34.5 wt% of gasoline fraction yield using CPO, whereas with UPO, the conversion was 70.9 wt% with gasoline fraction yield of 33.0 wt%. HZSM-5, beta zeolite, SBA-15 and AlSBA-15 as additives with REY increased the conversion and the yield of organic liquid product. The transport riser reactor can be used for the continuous production of biofuels from cracking of CPO and UPO over REY catalyst.     

Chemical analysis of materials used in pig housing with respect to the safety of products of animal origin

Bedding, environmental enrichment materials and disinfectant powders in pig farming are meant to ensure a hygienic bedding environment or allow pigs to perform explorative behaviour. To our knowledge, no legal regulation exists, that established maximum contents for undesirable substances, such as toxic metals, dioxins or trace elements in these materials, although oral ingestion could be expected. In the present study, a total of 74 materials (disinfectant powders [n = 51], earth/peat [n = 12], biochar [n = 8], recycled manure solids [n = 3]) were analysed for their content of various toxic metals, trace elements, dioxins and polychlorinated biphenyls. The data suggest that, in some samples, trace elements like iron, copper and zinc might have been added intentionally in order to induce physiological effects (iron supply to piglets, copper and zinc as growth promoter in pigs). Moreover, some materials contained high levels of lead, cadmium or arsenic. Consequently, if farm animals repeatedly consume environmental enrichment and bedding materials or disinfectant powders in considerable amounts and these quantities are added to the daily ration, the amount of ingested undesirable substances and trace elements might exceed the maximum levels set for complete feedstuffs, and an elevated transfer into food of animal origin might occur. Future studies are required to address the possible quantitative contribution in the light of feed and food safety. Finally, the excretion of undesirable substances with manure needs to be considered due to their possible accumulation in soils.     

Production of biodiesel from acid waste lard

The objective of the present work was: (i) to enable biodiesel production from acid waste lard; (ii) to study the esterification reaction as possible pre-treatment at different temperatures, catalyst amount and reaction times; (iii) to evaluate biodiesel quality according to EN 14214 after basic transesterification of the pre-treated fat; and (iv) to predict the impact of using such waste as raw material in mixture with soybean oil. Temperature and catalyst amount were the most important reaction conditions which mostly affected biodiesel quality, namely viscosity and purity. The selected pre-treatment conditions were 65 °C, 2.0 wt% H₂SO₄ and 5 h, which allowed obtaining a product with a viscosity of 4.81 mm² s⁻¹ and a purity of 99.6 wt%. The proposed pre-treatment was effective to enable acid wastes as single raw materials for biodiesel production with acceptable quality; however, low yields were obtained (65 wt%). Alkali transesterification of a mixture of waste lard and soybean oil resulted in a product with a purity of 99.8 wt% and a yield of 77.8 wt%, showing that blending might be an interesting alternative to recycle such wastes. Also, because in addition to using conventional and relatively economical processes, some biodiesel properties depending on the raw material composition (such as the iodine value) might even be improved.     

Short- versus Long-Term Effects of Elevated CO2 on Night-Time Respiration of Needles of Scots Pine (Pinus sylvestris L.)

Dark respiration rate in the night (R _D) was measured in five-year-old Scots pine (Pinus sylvestris L.) trees grown for two years under ambient (AC) and elevated (AC + 400 µmol mol^–1 = EC) CO₂ concentrations in open top chambers. Two needle age classes (i.e., current-year and one-year-old) were measured at AC and EC in both AC- and EC-grown pines. Additionally different chemical characteristics were determined on the needles, such as nitrogen (N), carbon (C), starch, and soluble sugar concentrations as well as specific leaf area. The direct, short-term and indirect, long-term effects of EC on R _D for the two needle age classes were examined. R _D was expressed on a per needle area, needle mass, N, C, and C/N bases. Direct effects were only pronounced in the AC treatment where inhibition of R _D was found at EC in both current- and one-year-old needles. Indirect effects were only significant in one-year-old needles where a decrease was found in the EC grown trees as compared with AC ones when R _D was expressed per unit needle mass, C, or C/N. R _D per unit needle area and needle N were not sensitive to long-term EC, in any needle age class. Long-term EC treatment also influenced the response of the two needle age classes. One-year-old needles from the EC treatment had significantly lower R _D than current-year needles, but no such response was observed in the AC treatment. Our experiment re-emphasised the importance of expressing R _D on different bases for a correct interpretation of the responses to EC. Moreover, we showed that different needle age classes can respond differently to a CO₂ enrichment.