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When the COB packaging LED light source is prepared by the centrifugal precipitation process, the phosphor forms a high-density phosphor layer on the chip surface. Centrifugal speed can change the vertical distribution of different kinds of particles in the phosphor coating, which affects the color parameters of the LED light source. Several different centrifugal speeds are used, the luminous flux of the sample has increased by about 5%, and the color temperature of the light source is also rising. The color temperature increases with the addition of the rotating speed, and the color temperature adds up to 278.6 K at 500 r/min and 422.4 K at 1000 r/min. The first reason for this phenomenon is that the proportion of large particles at the bottom of the phosphor layer formed by centrifugal precipitation (close to the chip) increases, which increases the conversion efficiency of phosphor. Second, after the powder is precipitated, a phosphor thin layer composed of very small particles will be formed on the upper surface of the phosphor layer. The higher the rotational speed, the thinner this thin layer, the smaller the absorption effect on the short-wave part of the spectrum, and the overall color temperature of the light source increases slightly. Third, the proportion of high-density yellow-green powder at the bottom of the phosphor layer formed by the centrifugal precipitation process is higher, and the photoluminescence produces a yellow-green band. [ABSTRACT FROM AUTHOR]

Saline soils can significantly affect methane (CH4) and nitrous oxide (N2O) in atmospheric greenhouse gases (GHGs). However, the coupling effect of nitrogen fertilization addition and saline soils on CH4 uptake and N2O emissions has rarely been examined under various salinity conditions of soil. In this study, the effects of nitrogen fertilization addition on CH4 and N2O fluxes under different salinity conditions of soil in Hetao Irrigation District, Inner Mongolia, were investigated by on-site static chamber gas chromatography. A slightly saline soil (S1) (Electrical Conductivity: 0.74 dS m−1) and a strongly saline soil (S2) (EC: 2.60 dS m−1) were treated at three levels of nitrogen fertilization: a high fertilization rate of 350 kg N ha−1 (H), a low fertilization rate of 175 kg N ha−1 (L), and no fertilizer (control treatment, referred to as CK). Nitrogen application was the important factor affecting N2O emissions and CH4 uptake in saline soil. The CK, L, and H treatments exhibited a cumulative CH4 uptake of 156.8–171.9, 119.7–142.0, and 86.7–104.8 mg m−2 in S1, 139.3–176.0, 109.6–110.6, and 68.5–75.4 mg m−2 in S2, respectively. The cumulative N2O emissions under the L and H treatments in S2 were 44.1–44.7%, and 74.1–91.1% higher than those in S1. Nitrogen fertilizer application to saline soils reduced CH4 uptake and promoted N2O emission in the Hetao Plain, Inner Mongolia. Our results indicate that mitigating soil salinity and adopting appropriated fertilizer amounts may help to cope with global climate change. [ABSTRACT FROM AUTHOR]

Selective hydrogenations of lignin-derived phenolic compounds represent essential processes in the chemical industry, especially for production of a multitude of fine chemicals. However, selective hydrogenation of phenolic compounds in water phase suffers from low conversion. Here we report a catalyst of well-dispersed Ru clusters fixed in N-doped mesoporous hollow carbon spheres (Ru@N-CS) for enhanced cyclohexanol productivity in phenol hydrogenation at mild aqueous condition. This superhydrophobicity carbon spheres appear to selectively allow diffusion of phenol and hydrogen molecules to the electron-rich coordination unsaturated Ru active sites, while confining the reactants there to enhance its reaction probability. The Ru@N-CS catalyst can selectively hydrogenate phenol at 80 °C and 0.5 MPa of H2 in 30 min in aqueous medium with phenol conversions of 100% and ~100% cyclohexanol selectivity, corresponding to cyclohexanol productivity up to 471 per g of Ru per minute. The TOF value is up to 9980 h−1, which 14 times more than Ru nanoparticles supported on N-doped carbon hollow spheres (Ru/N-CS). This work provides an important catalytic system for upgrading of bio-oil into value-added chemicals under mild aqueous-phase. [ABSTRACT FROM AUTHOR]

Based on the fact that flip chip without front-side bonding wire, a correlated color temperature (CCT) tunable chip on board (COB) light emittin g diodes (LED) light source was fabricated, by screen printing technology before the phosphor was coated on the whole luminous surface. A part of the blue LED chips in the light source excites the fluorescent glue to produce a warm white light (CCT = 2631 K), and the other part produces cool white light (CCT = 6181 K). When changing the driving current ratio of the two parts of the chips, the CCT of COB LED light source can be continuously adjusted between warm and cool white light. According to the measured data, the relationship between the CCT and the current ratio of the two parts is obtained by fitting. Within the tunable range of the CCT (2631 K to 6181 K), the color rendering index (CRI) is about 90. The minimum is 89.3 and the maximum is 93.1. While achieving tunable CCT and high CRI, the LED light source has a luminous flux of 1938.76 lm on a circular surface with a diameter of 11 mm. The overall luminous efficiency is close to 100 lm/W. [ABSTRACT FROM AUTHOR]

The pyrolysis of pine sawdust was carried out in a fixed bed reactor heated from 30 °C to a maximum of 700 °C in atmospheric nitrogen and pressurized hydrogen (5 MPa). The yield, elemental composition, thermal stability, and composition of the two pyrolysis bio-oils were analyzed and compared. The result shows that the oxygen content of the bio-oil (17.16%) obtained under the hydrogen atmosphere was lower while the heating value (31.40 MJ/kg) was higher than those of bio-oil produced under nitrogen atmosphere. Compounds with a boiling point of less than 200 °C account for 63.21% in the bio-oil at pressurized hydrogen atmosphere, with a proportion 14.69% higher than that of bio-oil at nitrogen atmosphere. Furthermore, the hydrogenation promoted the formation of ethyl hexadecanoate (peak area percentage 19.1%) and ethyl octadecanoate (peak area percentage 15.42%) in the bio-oil. Overall, high pressure of hydrogen improved the bio-oil quality derived from the pyrolysis of pine biomass. [ABSTRACT FROM AUTHOR]

A kind of chips on board (COB) package of light emitting diode (LED) light source is designed and produced. By reducing the current density and using the mirror aluminum substrate with high reflectivity to improve the luminous efficiency. Meanwhile, three kinds of red phosphors with peak wavelength of 630 nm, 631 nm and 639 nm are added on the basis of yellow‐green phosphors, which increase within the range of red light LED spectrum composition, improve the LED color rendering index. The measurement results show that under 500 mA forward current, the luminous flux density of LED on the luminous surface with an area of 227 mm2 reaches 14.4 lm/mm2, the luminous efficiency reaches 175.5 lm/W, and the color rendering index reaches 89.3. It is found in the process of measuring the LED color temperature changes slightly with the current change, and by calculating that the proportion of blue photons in the LED spectrum is increasing gradually, the cause of this phenomenon is the phosphor excitation efficiency is saturation when the optical power density is high, which is influenced in two aspects: the proportion of photons absorbed by phosphor or the phosphor excitation efficiency decreases, the two factors together or separately cause the phosphor excitation saturation effect. [ABSTRACT FROM AUTHOR]

The complete deoxygenation of palmitic acid followed by simultaneous hydro-isomerization and appropriate hydrocracking were achieved over Co/HMCM-49 bi-functional catalysts with the special structure of 12 MR cups and a low Si/Al ratio. This offered new insights into the design of bi-functional catalysts for carbon rearrangements during the upgrading of palmitic acid to jet fuel range alkanes. [ABSTRACT FROM AUTHOR]

Soil salinization adversely affects sustainable land use and limitation of greenhouse gas emission. Methane (CH4) uptake and the specific activity of methanotrophs in three saline-alkaline soils—S1, electrical conductivity (EC) 4.80 dS m−1; S2, EC 2.60 dS m−1; and S3, EC 0.74 dS m−1—were observed and measured across crop phenological development in the Hetao Irrigation District of Inner Mongolia, China. There were significant differences in CH4 uptake between the three soil types. The cumulative uptake of CH4 was 97.97 mg m−2, 109.49 mg m−2, and 150.0 mg m−2 in S1, S2, and S3, respectively. Cumulative CH4 uptake was 35%, 35%, and 53% lower in S1 than in S3, and was 27%, 28%, and 19% lower in S2 than in S3 in 2014, 2015, and 2016, respectively. Differences in CH4 uptake were driven by the different specific activities of the methanotrophs in the three soils, of which the key controlling factor was soil EC. The findings demonstrate that saline-alkaline soils with high EC led to low CH4 uptake and thereby significantly increased the total greenhouse effect of CH4. [ABSTRACT FROM AUTHOR]

Abstract: Aqueous‐phase ketonization of bio‐based acetic acid is important to improve the conversion efficiency of biomass resources. In this study, ZrMn mixed oxides (ZrMnOx) with high aqueous‐phase ketonization activity are synthetized through a carbonization/oxidation method (COM) and solvothermal method (STM). The results show that ZrMnOx prepared by COM possesses tetragonal ZrO2, and hausmannite Mn3O4 is observed only at a high oxidation temperature of 750 °C. Low‐temperature and long oxidation results in decreased crystallinity and crystallite size, which is related to highly dispersed Mnn+ species. The catalysts with improved acid sites possess high ketonization activity. Surface areas and pore size of ZrMnOx synthetized by STM are controlled by the solvents for thermal treatment. Compared with water as solvent, ethanol increases the surface area and pore size, resulting in high ketonization activity. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic conversion of palmitic acid was studied over Co/SiO2, H‐ZSM‐22 (HZ‐22), Co/H‐ZSM‐22 (Co/HZ‐22), mesoporous H‐ZSM‐22 (HZP‐22), and Co/H‐ZSM‐22 (Co/HZP‐22) catalysts. For the bifunctional catalysts, on the one hand, the porosity of zeolitic supports provided uniform accommodation for Co particles to realize the good distribution and downsizing of metal particles; on the other hand, the impregnation of Co into zeolitic supports improved the acidity of bifunctional catalysts that presented more weak/strong acid sites and stronger acid strength. Compared to sole metal centers over Co/SiO2 (no isomerization), the hydrodeoxygenation and hydroisomerization of palmitic acid were achieved simultaneously over bifunctional Co/HZ‐22 and Co/HZP‐22 catalysts (4 wt % Co loading) in one step. Mesoporous Co/HZP‐22 possessed an excellent catalytic performance during the upgrading of palmitic acid to yield the highest amount of iso‐alkanes. Importantly, the metal/zeolite bifunctional catalysts tailored the deoxygenation route significantly from hydrodecarbonylation (major) over sole metal catalysts or zeolites (only metal centers and only acid sites) to the hydrodeoxygenation route (major) over Co/zeolite bifunctional catalysts (both metal centers and acid sites). [ABSTRACT FROM AUTHOR]

A fused silica capillary reactor combined with a heating/cooling stage, a microscope and a digital camera were used to investigate phase behavior during the hydrothermal liquefaction of microalgae (Dunaliella tertiolecta) and model compounds, including soya protein and glycine, starch, glucose and xylose, stearic acid and palmitic acid. Bubbles were generated at 246°C and disappeared at 360°C upon heating whenDunaliella tertiolectaused as feedstocks. Moreover, liquid products were generated at 300°C upon heating and oily liquid products began to separate out at 250°C upon cooling. The phase behavior of soya protein was similar to that of theDunaliella tertiolecta. Meanwhile, there only observed the bubbles generation during hydrothermal liquefaction of glycine. Heating the starch, glucose and xylose above 350°C generated black solids from carbonization. Stearic acid and palmitic acid only had the process of melting, dissolution, dispersion and precipitation. [ABSTRACT FROM AUTHOR]

Aqueous-phase ketonization possesses significant advantages over gas- or organic-phase ketonization for improved conversion efficiency of aqueous fraction accompanied by algal bio-oil production. In this study, synthetized ZrO2 and Zr/Mn oxides are used for aqueous-phase ketonization of acetic acid. ZrMn0.5Ox shows the highest ketonization activity at 340°C for 12 h, achieving maximum acetone yield of 88.27%; and all catalysts exhibited selectivity higher than 96.75%. Apparent activation energy and acid reaction order are 161.2 kJ mol−1 and 0.70, respectively. Results suggest high ketonization activity of poorly crystallized tetragonal ZrO2. Addition of Mn results in ZrO2/MnOx solid solution and improves active sites. Acid property and Mn4+ content are important factors, and oxygen vacancy demonstrates relationship with ketonization activity for ZrO2. Examination of recovered catalysts indicates that ZrMnyOx exhibits improved stability, and Mn leaching and crystal phase transformation are main causes of deactivation in aqueous-phase ketonization. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2958-2967, 2017 [ABSTRACT FROM AUTHOR]

In this study, the analysis of organic compounds in the products obtained from hydrothermal liquefaction (HTL) of microalgae ( Dunaliella tertiolecta) was carried out, with particular attention on the identification of compounds in aqueous phases via the integration of two pre-treatment methods namely dried aqueous extracts (DAE) and solid-phase micro-extraction (SPME) along with GC-MS analysis. The results showed that the strong polar compounds in aqueous phases, such as carboxylic acids, alcohols, amides, glycerol, and N-containing compounds were determined through DAE method. The weak polar compounds like phenols, cyclic hydrocarbons, and indoles were identified via SPME method. In addition, CO2 and CO are the main components of the gaseous phase products, the rest of components include CH4, N2, H2, C2H4, C2H6, etc. Bio-oil is mainly composed of ketones, phenols, alcohols, hydrocarbons and N-containing compounds. Based on the compounds in the bio-oil, aqueous and gaseous phases compared with the other previous published works, the plausible pathways of Dunaliella tertiolecta HTL are proposed. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 259-268, 2017 [ABSTRACT FROM AUTHOR]

Bi-functional Mo/ZSM-22 catalysts were designed to upgrade palmitic acid and further to isomerize n-alkanes. Besides the effects on acidity, H+ cations might be beneficial for the distribution of MoOx particles, the higher surface Mo/Si ratio and the greater surface Mo4+ content of bi-functional Mo/ZSM-22 catalysts. In the upgrading of palmitic acid, strong acid sites of catalysts were proven to favor hydrodecarbonylation (HDC), isomerization and cracking. Mo6+ (or MoO3) preferred to support the HDC reaction, whereas Mo4+ (or MoO2) suitably improved the hydrodeoxygenation (HDO) reaction without carbon atom loss. That is, the Mo4+/Mo6+ ratio of Mo/ZSM-22 catalysts significantly influenced HDO/HDC selectivity. More importantly the improvement in HDO rather than HDC with the complete conversion of palmitic acid, could significantly decrease the negative effects of strong acid sites (such as HDC and cracking) to facilitate isomerization of n-alkanes to afford more branched alkanes with a higher iso-alkanes/n-alkanes ratio. [ABSTRACT FROM AUTHOR]

Different biobased chemicals are produced during the conversion of biomass into fuels through various feasible technologies (e.g., hydrolysis, hydrothermal liquefaction, and pyrolysis). The challenge of transforming these biobased chemicals with high hydrophilicity is ascribed to the high water content of the feedstock and the inevitable formation of water. Therefore, aqueous-phase processing is an interesting technology for the heterogeneous catalytic conversion of biobased chemicals. Different reactions, such as dehydration, isomerization, aldol condensation, ketonization, and hydrogenation, are applied for the conversion of sugars, furfural/hydroxymethylfurfural, acids, phenolics, and so on over heterogeneous catalysts. The activity, stability, and reusability of the heterogeneous catalysts in water are summarized, and deactivation processes and several strategies are introduced to improve the stability of heterogeneous catalysts in the aqueous phase. [ABSTRACT FROM AUTHOR]

A unique monodispersed MnCO/graphene nanosheet composite is synthesized by a simple one-step hydrothermal method and used as anode of lithium-ion battery. X-ray diffraction patterns show the typical rhombohedral structure of MnCO. A transmission electron micrograph reveals that MnCO is evenly distributed on the graphene nanosheet surface with a uniform diameter of 100 nm. Electrochemical performance results show that the specific discharge capacities of MnCO/graphene nanosheet composite remain above 1015.9 mAh g at a rate of 0.2 C after 85 cycles in the potential window of 0.01-2.0 V and even at a high rate of 1.0 C this parameter remains at 683.5 mAh g after 100 cycles. Thus, the composite also exhibits favorable rate performance. The excellent reversible capacities are attributed to the highly dispersed and large nanosheet structure of the composite, which may not only facilitate the fast transport of Li ions between the electrode and electrolyte but also provide enough surfaces to accommodate extra Li ions that contribute to partial interfacial storage capacities. Additionally, graphene nanosheet can effectively improve electrical conductivity of the composite. Therefore, MnCO/graphene nanosheet composite can be a great potential anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

In this article, two acid catalysts (ZrO2/SO42− and HZSM-5) and two base catalysts (MgO/MCM-41 and KtB) were used in catalytic hydrothermal liquefaction (HTL) of Dunaliella tertiolecta (D. tertiolecta) for the production of bio-oil. The results indicated that the acid/base property of the catalyst plays a crucial role in the catalytic HTL process, and the base catalyst is conducive to the improvement of conversion and bio-oil yield. When KtB was used as the catalyst, the maximum conversion and bio-oil yield was 94.84 and 49.09 wt %, respectively. The detailed compositional analysis of the bio-oil was performed using thermogravimetric analysis, elemental analysis, FT-IR, and GC-MS. The compositional analysis results showed that the introduction of catalyst is beneficial for reducing the fixed carbon content in the bio-oil, and the structure of catalyst influences on the bio-oil composition and boiling point distribution. Based on our results and previous studies, the probable catalytic HTL microalgae model over various catalysts can be described that the main chemical reactions include ketonization, decarboxylic, dehydration, ammonolysis, and so forth. with HZSM-5 and MgO/MCM-41 as the catalyst; the cyclodimerization, decomposition, Maillard reaction, and ketonization are the main reactions with ZrO2/SO42− as the catalyst; the dehydration, ammonolysis, Maillard reaction, and ketonization can occur with KtB as the catalyst. Therefore, a plausible reaction mechanism of the main chemical component in D. tertiolecta is proposed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1118-1128, 2015 [ABSTRACT FROM AUTHOR]

Nesquehonite, hydromagnesite, and brucite are important precursors for the preparation of high-purity magnesia (MgO) using magnesium resources from salt lake as raw materials. In this paper, TG-DTG and DSC were used to investigate the thermal decomposition behaviors of the three precursors. Decomposition kinetic parameters at each stage were evaluated based on the TG data using the iso-conversional method. Decomposition mechanisms were determined using the master-plots method. The decomposition temperature range, heat absorption, and kinetic parameters of the three phases were then compared. The most probable mechanism of each stage from the perspective of crystal structure was found to be consistent with the calculation results from the master-plots method. Results led to the conclusion that nesquehonite is the most appropriate precursor for the preparation of high-purity MgO. Further studies on precursor selection and calcining condition selection for the preparation of MgO using bischofite will benefit from this research. [ABSTRACT FROM AUTHOR]

Co-pyrolysis behaviors of plastics-biomass blends were investigated using a thermogravimetric (TG) analysis from room temperature to 873 K with a heating rate of 5-40 K min in an inert atmosphere. The selected biomass sample was sawdust of pine wood (WS). Polyvinyl chloride (PVC), low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP) were selected as plastic samples. The difference of mass loss between experimental and theoretical ones (calculated as arithmetic sums of those from each separated component) was used as a criterion of synergetic effect. The experimental results indicated that a significant synergetic effect existed during the high-temperature region of plastics and WS co-pyrolysis process, specially, the dehydrochlorination reaction of PVC and the degradation of hemicellulose and cellulose in the WS during the co-pyrolysis process showed synergetic effect, as well as the reaction of plastics (LDPE, HDPE, and PP) and WS. Based on the TG data with different heating rates, the kinetics parameters, especially activation energy, were calculated using the Friedman method. The activation energy of plastics, WS, and their blends were from 92.8 to 359.5 kJ mol. The activation energy of the PVC-WS blends was at a range of 180.2-254.5 kJ mol in the second stages. The activation energies range of LDPE-WS, HDPE-WS, and PP-WS blends were 164.5-229.6, 213.2-234.3, and 198.4-263.6 kJ mol, respectively. [ABSTRACT FROM AUTHOR]

Sulfonic acid functionalized mesoporous SBA-15 materials were prepared using the co-condensation and grafting methods, respectively, and their catalytic performance in the dehydration of xylose to furfural was examined. SBA-15-SO3H(C) prepared by the co-condensation method showed 92-95% xylose conversion and 74% furfural selectivity, and 68-70% furfural yield under the given reaction conditions. The deactivation and regeneration of the SBA-15-SO3H(C) catalyst for the dehydration of xylose was also investigated. The results indicate that the used and regeneration catalysts retained the SBA-15 mesoporous structure, and the S content of SBA-15-SO3H(C) almost did not change. The deactivation of the catalysts is proposed to be associated with the accumulation of byproducts, which is caused by the loss reaction of furfural. After regeneration by H2O2, the catalytic activity of the catalyst almost recovered. [ABSTRACT FROM AUTHOR]

Irrigation water is limiting for crop production in arid areas and application rates of fertilizers often exceed crop requirements, resulting in high accumulation of nitrate nitrogen (NO3−-N) in the soil. Management practices play a significant role in the leaching of NO3−-N. This experiment compares the effects of traditional furrow irrigation and sprinkler fertigation on the soil NO3−-N concentration trend throughout the cropping season in potato fields in China. Two irrigation systems that were fertilized, namely by furrow (NF-FI) and sprinkler fertigation (NF-SI), and two controlling without any fertilizer (C-FI and C-SI) were tested in the same experimental site for three consecutive years. Both the NF-FI soils and NF-SI soils with three replications and fertilizer applications of 273 kg N ha−1 exhibited a different trend of NO3−-N accumulation at different depths of soil profile. However, the magnitude of NO3−-N accumulation was low in the NF-SI soil profile. In NF-SI treatments, higher NO3−-N was observed at 20–40 cm soil layer. In the NF-FI, the concentration of the highest nitrate was observed at the 40–120 cm soil layer. The concentrations of NO3−-N in the fertilized soil were higher than those of the control soil for each irrigation system. Residual levels of NO3−-N in the soil depth of 40–120 cm from NF-FI were 1.54, 3.45 and 5.28 times higher than NF-SI after harvesting potatoes from 2015 to 2017. In NF-FI treatments, apparent nitrogen loss was 234.7, 237.5 and 276.7 kg ha−1 after harvesting potatoes in 2015, 2016 and 2017. Meanwhile, apparent nitrogen loss from NF-SI treatments was only 161.9, 132.1 and 148.9 kg ha−1, which was 31.0%, 44.4% and 46.2% lower than that of NF-FI in 2015, 2016 and 2017, respectively. The risk of NO3−-N leaching below the root zone from NF-FI was higher than that from NF-SI. It has been demonstrated that sprinkler fertigation can also be used as a tool for mitigating NO3−-N accumulation and apparent nitrogen loss. [ABSTRACT FROM AUTHOR]