Quantum spectroscopy of plasmonic nanostructures

We use frequency entangled photons, generated via spontaneous parametric down conversion, to measure the broadband spectral response of an array of gold nanoparticles exhibiting Fano-type plasmon resonance. Refractive index sensing of a liquid is performed by measuring the shift of the array resonance. This method is robust in excessively noisy conditions compared with conventional broadband transmission spectroscopy. Detection of a refractive index change is demonstrated with a noise level 70 times higher than the signal, which is shown to be inaccessible with the conventional transmission spectroscopy. Use of low photon fluxes makes this method suitable for measurements of photosensitive bio-samples and chemical substances.Comment: 11 pages, 5 figure

NtMYB4 and NtCHS1 Are Critical Factors in the Regulation of Flavonoid Biosynthesis and Are Involved in Salinity Responsiveness

High levels of salinity induce serious oxidative damage in plants. Flavonoids, as antioxidants, have important roles in reactive oxygen species (ROS) scavenging. In the present study, the tobacco R2R3 MYB type repressor, NtMYB4, was isolated and characterized. The expression of NtMYB4 was suppressed by salinity. Overexpression of NtMYB4 reduced the salt tolerance in transgenic tobacco plants. NtMYB4 repressed the promoter activity of NtCHS1 and negatively regulated its expression. Rutin accumulation was significantly decreased in NtMYB4 overexpressing transgenic plants and NtCHS1 RNAi silenced transgenic plants. Moreover, high H2O2 and O2− contents were detected in both types of rutin-reduced transgenic plants under high salt stress. In addition, exogenous rutin supplementation effectively scavenged ROS (H2O2 and O2−) and improved the salt tolerance of the rutin-reduced transgenic plants. In contrast, NtCHS1 overexpressing plants had increased rutin accumulation, lower H2O2 and O2− contents, and higher tolerance to salinity. These results suggested that tobacco NtMYB4 acts as a salinity response repressor and negatively regulates NtCHS1 expression, which results in the reduced flavonoid accumulation and weakened ROS-scavenging ability under salt stress

Effect of Particle Size on the Hydraulic Characteristics of Mechanically and Biologically Treated Waste

Mechanical biological treatment (MBT) is a waste processing technology that helps conserve resources and reduce emissions harmful to the environment. The treatment of municipal solid waste (MSW) using MBT is a hot topic in environmental geotechnical engineering. Permeability tests were carried out on MBT waste using a compression and permeability combined apparatus and a large-scale vertical permeability apparatus taking the influence of particle size into consideration. The permeability of samples with smaller particle sizes was found to be lower for the same pressure and dry mass (%) of component. The best-fit line between the logarithmic permeability and variables such as the dry density was linear. As the dry density increased or the void ratio decreased, the permeability of samples with smaller particles decreased more. The logarithmic permeability increased with the increase in the average particle size and void ratio. The permeabilities of MBT waste corresponding to particle size ranges of 0–10, 0–20, and 0–40 mm were 10−10–10−5, 10−8–10−4, and 10−5–10−3 m/s, respectively. The difference between MBT waste and MSW was analyzed in terms of their permeability. The results of MBT waste were compared with those reported in previous studies to provide reference for the permeability analysis of MBT landfills

Low-temperature pretreatment by AlCl3-catalyzed 1,4-butanediol solution for producing ‘ideal’ lignin with super-high content of β-O-4 linkages

High contents of internal β-O-4 linkages in lignin are critical for high-yield production of high-value aromatic monomers by depolymerization. However, it remains great challenge due to lack of suitable protection strategy. In this work, a very effective lignin-first strategy was developed to produce ideal lignin with a super high content of β-O-4 linkages (up to 72 %) from poplar, in which the pretreatment was undertaken at low temperatures of 90–130 °C with the use of AlCl3-catalyzed 1, 4-butanediol solution. 2D-HSQC NMR spectra revealed that lignin β-O-4 linkages were protected from etherification of the OH group by 1, 4-butanediol at the α position of lignin aliphatic chains. Besides, the OH groups at the γ position of lignin was also etherified, leading the formation of a structure of Ph-CH=CHCH2O(CH2)4OH. Interestingly, structure protection facilitated the formation of lignin nanoparticles via self-assembly (<100 nm). In addition, it was observed from pyrolysis results that addition of 1, 4-butanediol remarkably protected the structure of lignin by avoiding condensation, promoting the production of aromatics. The cellulose-rich fraction possessed a high cellulose digestibility of 91.64 % by enzymatic hydrolysis at a cellulase dosage of 15 FPU/g cellulose, approximately 6-fold untreated poplar (15.91 %). This low-temperature lignin-first strategy was of great importance for multi-products biorefining lignocellulose because it leads to the production of both lignin with super high content of β-O-4 linkages for depolymerization and highly digestible cellulose for sugar production.</p

Preparation of Ti-Doped ZnO/Bi₂O₃ Nanofilm Heterojunction and Analysis of Microstructure and Photoelectric Properties

Ti-doped ZnO (TZO) and Bi2O3 thin films were designed and deposited by magnetron sputtering successively on ITO glass substrate to form a Ti-doped ZnO/Bi2O3 (TZO/Bi2O3) heterojunction. Microstructure and photoelectric properties of TZO, Bi2O3, and TZO/Bi2O3 films were tested and characterized. The results showed that TZO film with a hexagonal wurtzite structure was preferentially grown along the crystal plane (002), had a good crystallization state, and was an N-type semiconductor film with high transmittance (90%) and low resistivity (4.68 × 10−3 Ω·cm). However, the Bi2O3 film sputtered in an oxygen-containing atmosphere and was a polycrystalline film that was preferentially grown along the crystal plane (111). It had a lower crystallization quality than TZO film and was a P-type semiconductor film with low transmittance (68%) and high resistance (1.71 × 102 Ω·cm). The I–V curve of TZO/Bi2O3 composite films showed that it had an obvious heterojunction rectification effect, which indicates that the PN heterojunction successfully formed in TZO/Bi2O3 films

Fractionation of light-colored lignin via lignin-first strategy and enhancement of cellulose saccharification towards biomass valorization

Highly efficient breaking lignocellulose cell wall recalcitrance towards biomass valorization still remains a great challenge. In this work, we developed a very effective lignin-first strategy using diols for direct fractionation of light-color lignin, and resulting in enhancement of enzymatic saccharification of cellulose-rich residues. The isolated lignin fraction possessed relatively higher content of β-O-4 linkages (26.6%), purity (>99%) and yield (>50%) and its brightness reached 22.0%ISO, which was 15.3, 13.5 and 1.9 folds higher than Kraft lignin, lignosulfonate and alkali lignin, respectively. In addition, the obtained nearly white-color lignin could be efficiently and directionally depolymerized into syringyl type phenols with high yields (82.0% of total phenols). Enzymatic hydrolysis efficiency of cellulose-rich residues was significantly enhanced up to 84.95% due to the more effective adsorption of cellulase under this diols strategy. Overall, the developed lignin-first strategy showed noteworthy preponderance on overcoming cell wall recalcitrance to achieve the whole lignocellulosic components valorization

Drift Reduction of a 4-DOF Measurement System Caused by Unstable Air Refractive Index

Laser beam drift greatly influences the accuracy of a four degrees of freedom (4-DOF) measurement system during the detection of machine tool errors, especially for long-distance measurement. A novel method was proposed using bellows to serve as a laser beam shield and air pumps to stabilize the refractive index of air. The inner diameter of the bellows and the control mode of the pumps were optimized through theoretical analysis and simulation. An experimental setup was established to verify the feasibility of the method under the temperature interference condition. The results indicated that the position stability of the laser beam spot can be improved by more than 79% under the action of pumping and inflating. The proposed scheme provides a cost-effective method to reduce the laser beam drift, which can be applied to improve the detection accuracy of a 4-DOF measurement system

Data from: Specific leaf area predicts dryland litter decomposition via two mechanisms

1. Litter decomposition plays important roles in carbon and nutrient cycling. In dryland both microbial decomposition and abiotic degradation (by UV light or other forces) drive variation in decomposition rates, but whether and how litter traits and position determine the balance between these processes is poorly understood. 2. We investigated relationships between litter quality and their decomposition rates among diverse plant species in a desert ecosystem in vertically contrasting positions representing distinct decomposition environments driven by different relative contributions of abiotic and microbial degradation. Thereto, leaf litter samples from 17 desert species were sealed into litterbags and placed on the soil surface under strong solar exposure versus shade conditions, or buried in the soil at 10 cm depth, for a whole year. 3. Litter decomposition rates were 21 and 17 % higher in burial and light-exposed treatments, respectively, than those in shade. Leaf traits, i.e. specific leaf area (SLA), litter C:N ratio and lignin concentration could predict litter decomposition to some degree, but their predictive power was dependent on litter position. However, multiple linear regression showed that SLA, litter C and P significantly affected k values for leaf litter decomposition besides litter position, with SLA standing out as a strong determinant of litter decomposition rate as related either to solar radiation or the environment below the soil surface. Furthermore, the interspecific differences in litter decomposition rate decreased over time, implying that afterlife effects of leaf traits on decomposition were attenuated. 4. Synthesis. These findings suggest that abiotic photodegradation and soil burial mediated microbial decomposition could be responsible for higher than expected litter turnover in dryland. They point to a dual role of specific leaf area as a promotor of decomposition rates: via relative exposure of the leaf surface to abiotic factors such as UV light versus to soil moisture and microbes under soil burial

Decomposition of 51 semidesert species from wide-ranging phylogeny is faster in standing and sand-buried than in surface leaf litters: implications for carbon and nutrient dynamics

Background and aims: Higher than expected litter decomposition rates have been observed in dry, sunny environments due to photochemical or physical degradation. However, our understanding of carbon and nutrient fluxes of standing and buried litters compared to surface litter in such areas is still scarce. Methods: We sampled leaf litters from 51 species in a semiarid dune ecosystem and incubated them in three positions: surface, sand-buried and simulated standing. Results: Decomposition was much faster in buried litter and somewhat faster in simulated standing litter than in surface litter. This pattern was independent of the incubation period, phylogenetic group or growth form. Litter position and incubation period significantly impacted litter nutrient dynamics. The nitrogen (N) and phosphorus (P) losses were faster in buried and simulated standing litters than in surface litter. The N loss was slower than P loss in 6-month decomposed litter but the former was relatively faster than the latter in the second phase up to 12 months of incubation. Conclusions: Our study shows that substantial mass and nutrient losses in simulated standing and buried litters can be a candidate explanation why drylands have higher carbon and nutrient fluxes than expected based on surface litter decomposition data alone