Facile hydrothermal synthesis of nitrogen rich blue fluorescent carbon dots for cell bio-imaging of Candida albicans

Nitrogen doped carbon dots (N-CDs) are well documented as an outstanding fluorogenic material for protein tags, live cell imaging and protein-receptor based fluorescence sensors owing to its good optical features with less cytotoxicity and better water solubility. In this regard, the present work describes the synthesis of nitrogen rich blue fluorescent carbon dots (NR-CDs) through hydrothermal treatment of citric acid monohydrate (CA) and 2-aminopyridine (2-AP). The optical properties of NR-CDs are further analyzed by common analytical methods viz., Fourier transform infrared (FT-IR), UV–visible (UV–vis) and Fluorescence spectroscopies. The surface chemical composition and morphology of NR-CDs are acquired by X-ray photo electron spectroscopy (XPS) and high resolution transmission electron microscopy (HR-TEM), respectively. The NR-CDs produce blue fluorescent at 421 nm at the excitation wavelength of 310 nm, the calculated quantum yield is about 18% with respect to standard quinine sulfate. The synthesized NR-CDs contains 15.03 wt % of N revealed by XPS results. Further, the NR-CDs are used as a fluorescence staining agent for cell imaging of Candida albicans (C. albicans) and the cytotoxicity are also measured. All the outcomes proposed that the NR-CDs act as good staining agent for C. albicans with less cytotoxicity.     

Dynamic responses of nitrous oxide emission and nitrogen use efficiency to nitrogen and biochar amendment in an intensified vegetable field in southeastern China

Intensive vegetable production exhibits contrasting characteristics of high nitrous oxide (N₂O) emissions and low nitrogen use efficiency (NUE). In an effort to mitigate N₂O emissions and improve NUE, a field experiment with nine consecutive vegetable crops was designed to study the combined effects of nitrogen (N) and biochar amendment and their interaction on soil properties, N₂O emission and NUE in an intensified vegetable field in southeastern China. We found that N application significantly increased N₂O emissions, N₂O–N emission factors and yield‐scaled N₂O emissions by 51–159%, 9–125% and 14–131%, respectively. Moreover, high N input significantly decreased N partial factor productivity (PFPN) and even yield during the seventh to ninth vegetable crops along with obvious soil degradation and mineral N accumulation. To the contrary, biochar amendment resulted in significant decreases in cumulative N₂O emissions, N₂O–N emission factor and yield‐scaled N₂O emissions by 5–39%, 16–67% and 14–53%, respectively. In addition, biochar significantly increased yield, PFPN and apparent recovery of N (ARN). Although without obvious influence during the first to fourth vegetable crops, biochar amendment mitigated N₂O emissions during the fifth to ninth vegetable crops. The relative effects of biochar amendments were reduced with increasing N application rate. Hence, while high N input produced adverse consequences such as mineral N accumulation and soil degradation in the vegetable field, biochar amendment can be a beneficial agricultural strategy to mitigate N₂O emissions and improve NUE and soil quality in vegetable field.     

Preparation and application of solvent‐modulated self‐doped N–S multicolour fluorescence carbon quantum dots

In this paper, two types of carbon quantum dot (CQDs) were prepared using biocompatible l ‐methionine as the carbon source and urea as the nitrogen source and a one‐step hydrothermal treatment. By changing the reaction solvents (deionized (DI) water and dimethylformamide (DMF)), the maximum emission of the resulting CQDs shifted from blue to red light. Specifically, the emission wavelength of the CQDs moved from 433 nm to 625 nm following embedding of a new functional group (–CONH–) on the surface of the CQDs. Photoluminescence quantum yields of the CQDs with blue and red emission reached 64% and 61%, respectively. The R‐CQDs were used to detect metal ions and a linear relationship was demonstrated between ln(F/F₀) and Fe³⁺ concentration in the range 0–0.5 mmol/L with a detection limit of 0.067 μM. Therefore these R‐CQDs have great potential as fluorescent probes for Fe³⁺ detection. We expect that the excellent water‐soluble, biocompatible and optical properties of the CQDs developed in this work mean that they will be widely used to detect biological cells.     

A solvothermal method to synthesize fluorescent carbon nanoparticles and application to photocatalysis and electrocatalysis

A novel solvothermal approach to synthesize fluorescent carbon nanoparticles (CNPs) was developed using glucose and ammonium oxalate as the carbon source, and glycol as the solvent. The solution of as‐prepared CNPs emitted blue‐green fluorescence under ultraviolet (UV) light at 365 nm, and the carbon nanoparticle formation was investigated through XRD, TEM, DLS, FT‐IR, UV, PL, XPS. The particle was well dispersed with an average diameter of about 10–30 nm. In contrast with previous methods, in this synthesis process neither strong acid treatment nor further surface modification was necessary. The solution of as‐prepared CNPs were applied to photocatalytic degradation of mountain green in the present H₂O₂, and the decolorization rate was over 97% when the reaction time was more than 7 h under visible light. The as‐prepared CNPs were also applied to electrocatalysis and showed excellent electrocatalytic activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Long‐term nitrogen addition modifies microbial composition and functions for slow carbon cycling and increased sequestration in tropical forest soil

Nitrogen (N) deposition is a component of global change that has considerable impact on belowground carbon (C) dynamics. Plant growth stimulation and alterations of fungal community composition and functions are the main mechanisms driving soil C gains following N deposition in N‐limited temperate forests. In N‐rich tropical forests, however, N deposition generally has minor effects on plant growth; consequently, C storage in soil may strongly depend on the microbial processes that drive litter and soil organic matter decomposition. Here, we investigated how microbial functions in old‐growth tropical forest soil responded to 13 years of N addition at four rates: 0 (Control), 50 (Low‐N), 100 (Medium‐N), and 150 (High‐N) kg N ha^?1 year^?1. Soil organic carbon (SOC) content increased under High‐N, corresponding to a 33% decrease in CO₂ efflux, and reductions in relative abundances of bacteria as well as genes responsible for cellulose and chitin degradation. A 113% increase in N₂O emission was positively correlated with soil acidification and an increase in the relative abundances of denitrification genes (narG and norB). Soil acidification induced by N addition decreased available P concentrations, and was associated with reductions in the relative abundance of phytase. The decreased relative abundance of bacteria and key functional gene groups for C degradation were related to slower SOC decomposition, indicating the key mechanisms driving SOC accumulation in the tropical forest soil subjected to High‐N addition. However, changes in microbial functional groups associated with N and P cycling led to coincidentally large increases in N₂O emissions, and exacerbated soil P deficiency. These two factors partially offset the perceived beneficial effects of N addition on SOC storage in tropical forest soils. These findings suggest a potential to incorporate microbial community and functions into Earth system models considering their effects on greenhouse gas emission, biogeochemical processes, and biodiversity of tropical ecosystems.     

Facile preparation of high fluorescent carbon quantum dots from orange waste peels for nonlinear optical applications

A facile and eco‐friendly hydrothermal method was used to prepare carbon quantum dots (CQDs) using orange waste peels. The synthesized CQDs were well dispersed and the average diameter was 2.9 ± 0.5 nm. Functional group identification of the CQDs was confirmed by Fourier transform infrared spectrum analysis. Fluorescence properties of the synthesized CQDs exhibited blue emission. The fluorescence quantum yield of the CQDs was around 11.37% at an excitation wavelength of 330 nm. The higher order nonlinear optical properties were examined using a Z‐scan technique and a continuous wave laser that was operated at a wavelength of 532 nm. Results demonstrated that the synthesis of CQDs can be considered as promising for optical switching devices, bio‐scanning, and bio‐imaging for optoelectronic applications.     

Simultaneous nitrogen and carbon removal in a packed A/O reactor: effect of C/N ratio on microbial community structure

In this research, a novel packed anoxic/oxic moving bed biofilm reactor (MBBR) was established to achieve high-organic matter removal rates, despite the carbon/nitrogen (C/N) ratio of 2.7–5.1 in the influent. Simultaneous nitrification–denitrification (SND) was investigated under a long sludge retention time of 104 days. The system exhibited excellent performance in pollutant removal, with chemical oxygen demand and total nitrogen (TN) enhanced to 93.6–97.4% and 34.4–60%, respectively. Under low C/N conditions, the nitrogen removal process of A/O MBBR system was mainly achieved by anaerobic denitrification. The increase of C/N ratio enhanced SND rate of the aerobic section, where dissolved oxygen was maintained at the range of 4–6 mg/L, and resulted in higher TN removal efficiency. The microbial composition and structures were analyzed utilizing the MiSeq Illumina sequencing technique. High-throughput pyrosequencing results indicated that the dominant microorganisms were Proteobacteria and Bacteroidetes at the phylum level, which contributes to the removal of organics matters. In the aerobic section, abundances of Nitrospirae (1.12–29.33%), Burkholderiales (2.15–21.38%), and Sphingobacteriales (2.92–11.67%) rose with increasing C/N ratio in the influent, this proved that SND did occur in the aerobic zone. As the C/N ratio of influent increased, the SND phenomenon in the aerobic zone of the system is the main mechanism for greatly improving the removal rate of TN in the aerobic section. The C/N ratio in the aerobic zone is not required to be high to exhibit good TN removal performance. When C/NH₄⁺ and C/TN in the aerobic zone were higher than 2.29 and 1.77, respectively, TN removal efficiency was higher than 60%, which means that carbon sources added to the reactor could be saved. This study would be vital for a better understanding of microbial structures within a packed A/O MBBR and the development of cost-efficient strategies for the treatment of low C/N wastewater.

     

Dramatic loss of inorganic carbon by nitrogen‐induced soil acidification in Chinese croplands

Intensive crop production systems worldwide, particularly in China, rely heavily on nitrogen (N) fertilization, but left more than 50% of fertilizer N in the environment. Nitrogen (over) fertilization and atmospheric N deposition induce soil acidification, which is neutralized by soil inorganic carbon (SIC; carbonates), and carbon dioxide (CO₂) is released to the atmosphere. For the first time, the loss of SIC stocks in response to N‐induced soil acidification was estimated for Chinese croplands from 1980 to 2020 and forecasts were made up to 2100. The SIC stocks in croplands in 1980 were 2.16 Pg C (16.3 Mg C/ha) in the upper 40 cm, 7% (0.15 Pg C; 1.1 Mg C/ha) of which were lost from 1980 to 2020. During these 40 years, 7 million ha of cropland has become carbonate free. Another 37% of the SIC stocks may be lost up to 2100 in China, leaving 30 million ha of cropland (37.8%) without carbonates if N fertilization follows the business‐as‐usual (BAU) scenario. Compared to the BAU scenario, the reduction in N input by 15%–30% after 2020 (scenarios S1 and S2) will decrease carbonate dissolution by 18%–41%. If N input remains constant as noted in 2020 (S3) or decreases by 1% annually (S4), a reduction of up to 52%–67% in carbonate dissolution is expected compared to the BAU scenario. The presence of CaCO₃ in the soil is important for various processes including acidity buffering, aggregate formation and stabilization, organic matter stabilization, microbial and enzyme activities, nutrient cycling and availability, and water permeability and plant productivity. Therefore, optimizing N fertilization and improving N‐use efficiency are important for decreasing SIC losses from acidification. N application should be strictly calculated based on crop demand, and any overfertilization should be avoided to prevent environmental problems and soil fertility decline associated with CaCO₃ losses.     

Methylene blue as a suppessor of the genotoxic effect of ultraviolet radiation with a wavelength of 300–400 nm

Ultraviolet radiation with a wavelength of 300–400 nm is characteristic of sunlight at the earth surface and causes DNA damage mediated by energy transfer to O₂ with the transformation of the latter in the singlet state. In connection with this, scavengers of reactive oxygen species (ROSs) are potential protectors against the genotoxic effect of this kind of radiation. It was found that the methylene blue dye at doses differing by several orders of magnitude from those that are toxic for humans is able to suppress completely the SOS response induced by UV with a wavelength of 300–400 nm in Escherichia coli.     

Gaseous emissions from management of solid waste: a systematic review

The establishment of sustainable soil waste management practices implies minimizing their environmental losses associated with climate change (greenhouse gases: GHGs) and ecosystems acidification (ammonia: NH₃). Although a number of management strategies for solid waste management have been investigated to quantify nitrogen (N) and carbon (C) losses in relation to varied environmental and operational conditions, their overall effect is still uncertain. In this context, we have analyzed the current scientific information through a systematic review. We quantified the response of GHG emissions, NH₃ emissions, and total N losses to different solid waste management strategies (conventional solid storage, turned composting, forced aerated composting, covering, compaction, addition/substitution of bulking agents and the use of additives). Our study is based on a meta‐analysis of 50 research articles involving 304 observations. Our results indicated that improving the structure of the pile (waste or manure heap) via addition or substitution of certain bulking agents significantly reduced nitrous oxide (N₂O) and methane (CH₄) emissions by 53% and 71%, respectively. Turned composting systems, unlike forced aerated composted systems, showed potential for reducing GHGs (N₂O: 50% and CH₄: 71%). Bulking agents and both composting systems involved a certain degree of pollution swapping as they significantly promoted NH₃ emissions by 35%, 54%, and 121% for bulking agents, turned and forced aerated composting, respectively. Strategies based on the restriction of O₂ supply, such as covering or compaction, did not show significant effects on reducing GHGs but substantially decreased NH₃ emissions by 61% and 54% for covering and compaction, respectively. The use of specific additives significantly reduced NH₃ losses by 69%. Our meta‐analysis suggested that there is enough evidence to refine future Intergovernmental Panel on Climate Change (IPCC) methodologies from solid waste, especially for solid waste composting practices. More holistic and integrated approaches are therefore required to develop more sustainable solid waste management systems.     

Bioenergy by‐products as soil amendments? Implications for carbon sequestration and greenhouse gas emissions

An important but little understood aspect of bioenergy production is its overall impact on soil carbon (C) and nitrogen (N) cycling. Increased energy production from biomass will inevitably lead to higher input of its by‐products to the soil as amendments or fertilizers. However, it is still unclear how these by‐products will influence microbial transformation processes in soil, and thereby its greenhouse gas (GHG) balance and organic C stocks. In this study, we assess C and N dynamics and GHG emissions following application of different bioenergy by‐products to soil. Ten by‐products were selected from different bioenergy chains: anaerobic digestion (manure digestates), first generation biofuel by‐products (rapeseed meal, distilled dried grains with solubles), second‐generation biofuel by‐products (nonfermentables from hydrolysis of different lignocellulosic materials) and pyrolysis (biochars). These by‐products were added at a constant N rate (150 kg N ha^?1) to a sandy soil and incubated at 20 °C. After 60 days, >80% of applied C had been emitted as CO₂ in the first‐generation biofuel residue treatments. For second‐generation biofuel residues this was approximately 60%, and for digestates 40%. Biochars were the most stable residues with the lowest CO₂ loss (between 0.5% and 5.8% of total added C). Regarding N₂O emissions, addition of first‐generation biofuel residues led to the highest total N₂O emissions (between 2.5% and 6.0% of applied N). Second‐generation biofuel residues emitted between 1.0% and 2.0% of applied N, with the original feedstock material resulting in similar N₂O emissions and higher C mineralization rates. Anaerobic digestates resulted in emissions <1% of applied N. The two biochars used in this study decreased N₂O emissions below background values. We conclude that GHG dynamics of by‐products after soil amendment cannot be ignored and should be part of the lifecycle analysis of the various bioenergy production chains.     

不同管理模式对农田生态系统服务的影响模拟研究——以太湖流域为例

高强度的农业生产给生态环境带来诸多负面影响,如何权衡农田生态系统服务是农业可持续发展面临的重要问题之一。本文以太湖流域稻麦轮作农田生态系统为研究对象,利用基于0—10cm土壤温度、10—20cm土壤温度、水稻生物量和小麦生物量等为目标函数的PEST软件校准APSIM模型,遴选三类重要生态系统服务——粮食供给(粮食产量)、水质调节(氮流失)和气候调节(N_2O排放、固碳-土壤有机碳),针对不同秸秆还田(无秸秆还田、稻秆还田麦秆不还田、麦秆还田稻秆不还田、稻麦秆全还田)和施肥模式(0、-5%,-10%,-20%)等设定16种情景模拟1986—2015年太湖流域生态系统服务变化趋势,利用自组织映射法(SOM)分析其权衡协同关系变化,以期为农田生态系统管理提供科学依据。结果表明:(1)相对秸秆还田,粮食产量、N_2O排放、氮流失和土壤有机碳受施肥影响更为显著,均随施肥量减少而下降;(2)不同管理模式对固碳影响较弱,对N_2O排放和水质调节影响明显,稻麦秆全还田且减量施肥5%、10%或20%情景对N_2O排放抑制最为有效,减排量均超过30%,氮流失量减量大于7%;(3)粮食供给与固碳、N_2O排放均存在显著的协同关系,粮食供给与水质调节、固碳与水质调节、水质调节与N_2O排放呈显著权衡关系,固碳与N_2O排放呈弱权衡关系;(4)基于N_2O排放量和氮流失量均低于基准模拟且粮食单位产量减少低于5%的情景下,无秸秆还田且减量施肥5%(S0_F1)和稻麦秆全还田且减量施肥5%(S3_F1)两种模式相对有利于整体提升太湖流域农田生态生态系统服务。此外,APSIM模型有待更多的野外监测数据进一步校准改进以提高模型率定精度,同时需扩展不同模式影响下太湖流域农田生态系统服务综合效应评估,以获取更加科学、合理的优化模式与途径。     

Simulating soil N2O emissions and heterotrophic CO2 respiration in arable systems using FASSET and MoBiLE-DNDC

Modelling of soil emissions of nitrous oxide (N₂O) and carbon dioxide (CO₂) is complicated by complex interactions between processes and factors influencing their production, consumption and transport. In this study N₂O emissions and heterotrophic CO₂ respiration were simulated from soils under winter wheat grown in three different organic and one inorganic fertilizer-based cropping system using two different models, i.e., MoBiLE-DNDC and FASSET. The two models were generally capable of simulating most seasonal trends of measured soil heterotrophic CO₂ respiration and N₂O emissions. Annual soil heterotrophic CO₂ respiration was underestimated by both models in all systems (about 10?C30% by FASSET and 10?C40% by MoBiLE-DNDC). Both models overestimated annual N₂O emissions in all systems (about 10?C580% by FASSET and 20?C50% by MoBiLE-DNDC). In addition, both models had some problems in simulating soil mineral nitrogen, which seemed to originate from deficiencies in simulating degradation of soil organic matter, incorporated residues of catch crops and organic fertilizers. To improve the performance of the models, organic matter decomposition parameters need to be revised.     

Indonesia’s blue carbon: a globally significant and vulnerable sink for seagrass and mangrove carbon

The global significance of carbon storage in Indonesia’s coastal wetlands was assessed based on published and unpublished measurements of the organic carbon content of living seagrass and mangrove biomass and soil pools. For seagrasses, median above- and below-ground biomass was 0.29 and 1.13 Mg C ha^?1 respectively; the median soil pool was 118.1 Mg C ha^?1. Combining plant biomass and soil, median carbon storage in an Indonesian seagrass meadow is 119.5 Mg C ha^?1. Extrapolated to the estimated total seagrass area of 30,000 km², the national storage value is 368.5 Tg C. For mangroves, median above- and below-ground biomass was 159.1 and 16.7 Mg C ha^?1, respectively; the median soil pool was 774.7 Mg C ha^?1. The median carbon storage in an Indonesian mangrove forest is 950.5 Mg C ha^?1. Extrapolated to the total estimated mangrove area of 31,894 km², the national storage value is 3.0 Pg C, a likely underestimate if these habitats sequester carbon at soil depths >1 m and/or sequester inorganic carbon. Together, Indonesia’s seagrasses and mangroves conservatively account for 3.4 Pg C, roughly 17 % of the world’s blue carbon reservoir. Continued degradation and destruction of these wetlands has important consequences for CO₂ emissions and dissolved carbon exchange with adjacent coastal waters. We estimate that roughly 29,040 Gg CO₂ (eq.) is returned annually to the atmosphere–ocean pool. This amount is equivalent to about 3.2 % of Indonesia’s annual emissions associated with forest and peat land conversion. These results highlight the urgent need for blue carbon and REDD+ projects as a means to stem the decline in wetland area and to mitigate the release of a significant fraction of the world’s coastal carbon stores.     

High-performance liquid chromatographic method for the determination of AG-331, a novel anti-cancer agent,in human serum and urine using solid-phase extraction and photodiode-array detection

A reversed-phase isocratic high-performance liquid chromatographic method has been developed for the determination of AG-331, a novel thymidylate synthase inhibitor, in human serum and urine. The method involves a solid-phase extraction from C₁₈ cartridges without addition of an internal standard. The methanol eluent is evaporated under nitrogen at 40°C, and reconstituted in mobile phase, acetonitrile-water (35:65, v/v) containing 25 mM ammonium phosphate. Separation of AG-331 was obtained on a C₁₈ column at a flow-rate of 1 ml/min. Chromatographic signals were monitored by a photodiode-array detector at a primary wavelength of 457 nm with a bandwidth of 4.8 nm. Standard curves are linear in the range of 22–2175 ng/ml in plasma and 44–2175 ng/ml in urine, respectively. The extraction recovery ranged from 92.9–102.4%. Intra-day coefficient of variation was less than 9.5%, and inter-day coefficient of variation was less than 14.3% for an AG-331 concentration of 44 ng/ml. This method has been used to characterize the pharmacokinetics of AG-331 in cancer patients as part of ongoing Phase I trials.     

Biodegradation of gasoline: kinetics, mass balance and fate of individual hydrocarbons

The degradation of gasoline by a microflora from an urban waste water activated sludge was investigated in detail. Degradation kinetics were studied in liquid cultures at 30 degrees C by determination of overall O2 consumption and CO2 production and by chromatographic analysis of all 83 identifiable compounds. In a first fast phase (2 d) of biodegradation, 74% of gasoline, involving mostly aromatic hydrocarbons, was consumed. A further 20%, involving other hydrocarbons, was consumed in a second slow phase (23 d). Undegraded compounds (6% of gasoline) were essentially some branched alkanes with a quaternary carbon or/and alkyl chains on consecutive carbons but cycloalkanes, alkenes and C10- and C11-alkylated benzenes were degraded. The degradation kinetics of individual hydrocarbons, determined in separate incubations, followed patterns similar to those observed in cultures on gasoline. Carbon balance experiments of gasoline degradation were performed. The carbon of degraded gasoline was mainly (61.7%) mineralized into CO2, the remaining carbon being essentially converted into biomass.     

滇中高原云南松林枯落物输入对土壤碳氮储量及其分布格局的影响

为了更好地理解土壤碳氮对枯落物输入变化的响应,通过枯落物添加与去除实验（DIRT）对滇中高原云南松林枯落物输入变化对土壤碳氮储量及其分布格局的影响进行了研究。2018年3月至2019年2月分别设置6种枯落物输处理,分别为对照（CO）、去除枯落物（NL）、双倍枯落物（DL）、去除根系（NR）、无输入（NI）以及去除有机层与A层（O/A-Less）,研究了不同处理条件下土壤剖面上碳氮储量的分布规律。研究结果表明：（1）不同处理全碳储量为134.49-170.92 t/hm²,全碳储量在不同处理间表现为：S_C（NL）=170.92 t/hm² > S_C（CO）=168.10 t/hm² > S_C（NR）=153.26 t/hm² > S_C（NI）=147.20 t/hm² > S_{C（O/A-Less）}=143.54 t/hm² > S_C（DL）=134.49 t/hm²,不同处理0-20 cm土层全碳储量占0-60 cm土层全碳储量的40.86%-53.56%;不同处理全氮储量表现为：S_N（CO）=11.83 t/hm² > S_N（NL）=9.70 t/hm² > S_N（DL）=8.70 t/hm² > S_N（NR）=8.35 t/hm² > S_{N（O/A-Less）}=8.21 t/hm² > S_N（NI）=8.09 t/hm²。不同处理0-20 cm土层的全氮储量占0-60 cm土层全氮储量的39.28%-46.04%。云南松林地枯落物添加去除实验发现去除枯落物短期内可以增加土壤碳储量,其他处理均在一定程度上减少了土壤碳氮储量。（2）地上枯落物输入对表层（0-20 cm）土壤碳氮影响显著,根系输入对深层（20-40 cm）土壤碳氮影响显著;（3）土壤C、N存在耦合关系,不同处理土壤全碳含量与全氮含量极显著正相关,并且土壤全碳含量与土壤各化学计量比均呈极显著正相关关系;土壤容重与土壤碳氮含量具有极显著负相关关系。     

Vibrational spectra of the diammineplatinum(II) disodium 5′-uridine monophosphate blue complex

The blue complexes produced by reaction of cis-diamminediaquoplatinum(II) nitrate, [cis-Pt(NH₃)₂(H₂O)₂](NO₃)₂, with disodium 5′-uridine monophosphate, 5′-UMP(Na₂), in H₂O and D₂O have been investigated by FT-IR spectroscopy. On the basis of the spectral changes observed in the CO stretching region during the reactions, chelation of the amidate N(3)··O(2) moiety to Pt(II) appears to be more likely than N(4)··O(4) chelation. The antisymmetric PO stretching mode of the PO_3²⁻ group of 5′-UMP splits into a triplet on complex formation indicating that PO_3²⁻ plays an important role in the structure of the platinum blue complexes. In addition, the sugar moiety of 5′-UMP apparently adopts a predominantly C(3′)-endo conformation in the solid blue complex. Finally, Raman microprobe spectroscopy of the solid provides some evidence for PtN(3) bond formation.     

Stability of luminescence in LaPO4, LaPO4:RE3+ (RE = Dy,Eu) nanophosphors

The property of high refractive index, low solubility in water as well as stability to high temperature variation of lanthanum phosphate (LaPO₄) proved it was the most effective candidate for the production of display lamps, and plasma display panel devices and sensors. The morphological and nanostructural characteristics play a key role in the working efficiency of the luminescent material. These properties can be controlled by the synthesis method, which we have adopted in this paper. We have prepared LaPO₄ nanoparticles at a relatively low temperature (110 ºC) in polyethylene glycol medium by using a wet chemical one‐step synthesis. The phase composition and structural properties of the sample have been characterized by X‐ray diffraction, Fourier transform infrared, transmission electron microscopy and the luminescent property by photoluminescence and thermoluminescence. The samples were well crystallized and the average crystallite size of 15 nm has been calculated for pure LaPO₄ using the Debye–Scherrer equation. The result from heat‐treated samples shows the phase combination and morphological structure of the powder depend on the annealing temperature. The heat treatment changes the structure of LaPO₄ from cuboid rods to fine grains at about 600 °C. The emission spectrum of LaPO₄ shows the broad emission band at 368 nm and shoulder at 465 nm with emission of blue color when monitored at an excitation wavelength at 256 nm. The stability of phosphor has been studied with respect to humidity, temperature, doping, doping concentration, γ‐ray exposures, etc. The prepared nanosized phosphors were thermally stable and may be a promising blue phosphor for lighting technology as well as radiation dosimetry. Copyright © 2014 John Wiley & Sons, Ltd.     

Response of soil carbon dioxide fluxes,soil organic carbon and microbial biomass carbon to biochar amendment: a meta‐analysis

Biochar as a carbon‐rich coproduct of pyrolyzing biomass, its amendment has been advocated as a potential strategy to soil carbon (C) sequestration. Updated data derived from 50 papers with 395 paired observations were reviewed using meta‐analysis procedures to examine responses of soil carbon dioxide (CO₂) fluxes, soil organic C (SOC), and soil microbial biomass C (MBC) contents to biochar amendment. When averaged across all studies, biochar amendment had no significant effect on soil CO₂ fluxes, but it significantly enhanced SOC content by 40% and MBC content by 18%. A positive response of soil CO₂ fluxes to biochar amendment was found in rice paddies, laboratory incubation studies, soils without vegetation, and unfertilized soils. Biochar amendment significantly increased soil MBC content in field studies, N‐fertilized soils, and soils with vegetation. Enhancement of SOC content following biochar amendment was the greatest in rice paddies among different land‐use types. Responses of soil CO₂ fluxes and MBC to biochar amendment varied with soil texture and pH. The use of biochar in combination with synthetic N fertilizer and waste compost fertilizer led to the greatest increases in soil CO₂ fluxes and MBC content, respectively. Both soil CO₂ fluxes and MBC responses to biochar amendment decreased with biochar application rate, pyrolysis temperature, or C/N ratio of biochar, while each increased SOC content enhancement. Among different biochar feedstock sources, positive responses of soil CO₂ fluxes and MBC were the highest for manure and crop residue feedstock sources, respectively. Soil CO₂ flux responses to biochar amendment decreased with pH of biochar, while biochars with pH of 8.1–9.0 had the greatest enhancement of SOC and MBC contents. Therefore, soil properties, land‐use type, agricultural practice, and biochar characteristics should be taken into account to assess the practical potential of biochar for mitigating climate change.