Efficient production of xylooligosaccharides from Camellia oleifera shells pretreated by pyruvic acid at lower temperature.

XOS production from lignocellulose using organic carboxylic acids and alkyd acids has been widely reported. However, it still faces harsh challenges such as high energy consumption, high cost, and low purity. Pyruvic acid (PYA), a carbonyl acid with carbonyl and carboxyl groups, was used to produce XOS due to its stronger catalytic activity. In this work, XOS was efficiently prepared from COS in an autoclave under the condition of 0.21 M PYA-121 °C-35 min. The total yield of XOS reached 68.72 % without producing any toxic by-products, including furfural (FF) and 5-hydroxymethylfurfural (5-HMF). The yield of xylobiose (X2), xylotriose (X3), xylotetraose (X4), and xylopentaose (X5) were 20.58 %, 12.47 %, 15.74 %, and 10.05 %, respectively. Meanwhile, 89.05 % of lignin was retained in the solid residue, which provides a crucial functional group for synthesizing layered carbon materials (SRG-a). It achieves excellent electromagnetic shielding (EMS) performance through graphitization, reaching -30 dB at a thickness of 2.0 mm. The use of a PYA catalyst in the production of XOS has proven to be an efficient method due to lower temperature, lower acid consumption, and straightforward operation.

Engineering the Quaternary Hydrotalcite-Derived Ce-Promoted Ni-Based Catalysts for Enhanced Low-Temperature CO2 Hydrogenation into Methane.

Ce-promoted NiMgAl mixed-oxide (NiCex-C, x = 0, 1, 5, 10) catalysts were prepared from the quaternary hydrotalcite precursors for CO2 hydrogenation to methane. By engineering the Ce contents, NiCe5-C showed its prior catalytic performance in low-temperature CO2 hydrogenation, being about three times higher than that of the Ce-free NiCe0-C catalyst (turnover frequency of NiCe5-C and NiCe0-C: 11.9 h-1 vs. 3.9 h-1 @ 225 °C). With extensive characterization, it was found that Ce dopants promoted the reduction of NiO by adjusting the interaction between Ni and Mg(Ce)AlOx support. The highest ratio of surface Ni0/(Ni2+ + Ni0) was obtained over NiCe5-C. Meanwhile, the surface basicity was tailored with Ce dopants. The strongest medium-strength basicity and highest capacity of CO2 adsorption was achieved on NiCe5-C with 5 wt.% Ce content. The TOF tests indicated a good correlation with medium-strength basicity over the NiCex-C samples. The results showed that the high medium-strength and Ce-promoted surface Ni0 species endows the enhanced low-temperature catalytic performance in CO2 hydrogenation to methane.

Investigating the Effect of Low-Temperature Drilling Process on the Mechanical Behavior of CFRP.

Previous research has found that lower temperature drilling is helpful to improve the hole quality of carbon fiber reinforced polymer (CFRP). However, the influence of the lower temperature drilling process on the mechanical behavior of composites is yet not fully understood. To examine the influence of the lower temperature drilling process on the mechanical behavior of CFRP, the open hole CFRP specimens used for mechanical tests were obtained with three cases: drilling with -25 °C/uncoated carbide drills/(1000 rpm, 0.02 mm/r), 23 °C/coated carbide drills/(4000 rpm, 0.03 mm/r), and 23 °C/uncoated carbide drills/(1000 rpm, 0.02 mm/r), respectively; corresponding, three groups of open-hole specimens are obtained: specimens drilling at low-temperature with low damage, specimens drilling at room-temperature with low damage and specimens drilling at room-temperature with low damage; the mechanical behavior of the three groups specimens were obtained by static tensile, tensile-tensile fatigue cyclic tests and residual tensile strength test. The results have shown that the mechanical properties of specimens with a low-temperature drilling process is lower than those of the specimen with a normal drilling process due to the better drilling quality. The damage accumulation in specimens was increased with the damage degree of the original hole, the greater the damage degree, the worse the mechanical properties.

The Influence of Lower Temperature Induction of Valsa mali on the Infection of Apple Trees.

Apple valsa canker (AVC), caused by Valsa mali, is one of the most important diseases of apple trees in China. AVC occurred severely along with cold winter or cold spring. However, the effect of lower temperature on V. mali is poorly understood. This study evaluated the influence of lower temperature pretreatment of V. mali on the infection of apple twigs and leaves. The results showed that exposing V. mali to lower temperatures (between -10°C and 10°C) for more than 18 h significantly increased the disease severity of apple leaves and twigs, with a higher lesion area ratio (LAR), lesion length, and disease incidence (DI) than that at 25°C. In addition, cold treatment ranging from -5°C to 10°C promoted colony growth. Meanwhile, the relative expression of four cell wall degrading enzyme (CWDE)-related genes pretreated at -5°C and 5°C were significantly higher than that at 25°C. The results indicated that the virulence of V. mali mycelium is sensitive to lower temperatures. After sensing lower temperature changes, V. mali can adjust its infection of apple trees by regulating the expression of pathogenicity gene and growth rate. Spring has very frequent temperature changes, and V. mali is highly invasive in this season. Therefore, more attention should be paid in spring to protecting apple trees from infection of V. mali, by reducing pruning wound formation in spring and applying protective agents to pruning wounds in time.

Stagewise resolution of temperature-dependent embryonic and postembryonic development in the cowpea seed beetle Callosobruchus maculatus (F.).

BACKGROUND: The thermal plasticity of life-history traits receives wide attention in the recent biological literature. Of all the temperature-dependent traits studied, developmental rates of ectotherms are especially often addressed, and yet surprisingly little is known about embryonic responses to temperature, including changes in the thermal thresholds and thermal sensitivity during early development. Even postembryonic development of many cryptically living species is understood superficially at best. RESULTS: This study is the first to estimate the exact durations of developmental stages in the cowpea seed beetle C. maculatus from oviposition to adult emergence at five permissive constant temperatures from 20 to 32 °C. Early embryonic development was tracked and documented by means of destructive sampling and subsequent confocal imaging of fluorescently stained specimens. Late embryonic and early larval development was studied with the use of destructive sampling and light microscopy. Well-resolved temporal series based on thousands of embryos allowed precise timing of the following developmental events: formation of the blastoderm; formation, elongation, and retraction of the germ band; dorsal closure; the onset and completion of sclerotization of the cuticle; hatching, and penetration of the first-instar larva into the cowpea seed. Pupation and adult eclosion were observed directly through an incision in the seed coat. The thermal phenotype of C. maculatus was found to vary in the course of ontogeny and different stages scaled disproportionately with temperature, but pitfalls and caveats associated with analyses of relative durations of individual stages are also briefly discussed. CONCLUSION: Disproportionate changes in developmental durations with temperature may have important implications when study design requires a high degree of synchronization among experimental embryos or when the occurrence of particular stages in the field is of interest, as well as in any other cases when development times need to be estimated with precision. This work provides one of the first examples of integration of embryological techniques with ecophysiological concepts and will hopefully motivate similar projects in the future. While experiments with Drosophila continue to be the main source of information on animal development, knowledge on other model species is instrumental to building a broader picture of developmental phenomena.

Aldehyde dehydrogenase plays crucial roles in response to lower temperature stress in Solanum tuberosum and Nicotiana benthamiana.

The aim of this study is to elucidate the role of ALDH2B7a during the response to lower temperature in Solanum tuberosum. This gene was found to have altered intragenic DNA methylation status in our previous reports. A total of 18 orthologs of StALDH2B7a were identified in the S. tuberosum genome, which were then divided into 8 aldehyde dehydrogenase (ALDH) subfamilies. The methylation statuses of four intragenic cytosine sites in intron 5 and exon 6 of genomic StALDH2B7a were altered by lower temperature stress, resulting in changes in the expression of StALDH2B7a. Silencing of NbALDH2C4, a homolog of StALDH2B7a in Nicotiana benthamiana, resulted in plants which were sensitive to lower temperature and accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA). These data suggested that the expression of StALDH2B7a was upregulated by alteration of its intragenic cytosine methylation status during lower temperature stress, and additional StALDH2B7a enzymes scavenged excess aldehydes resulting from ROS in a response to cold stress in potato. Our study expands the understanding of the mechanisms involved in plant responses to lower temperature, and provides a new gene source to improve potato tolerance to cold stress in northern China, where lower temperature is one of the key limiting factors for crop production.

Synthesis of liquid fuel via direct hydrogenation of CO2.

Synthesis of liquid fuels (C5+ hydrocarbons) via CO2 hydrogenation is very promising. Hydrogenation of CO2 to liquid hydrocarbons usually proceeds through tandem catalysis of reverse water gas shift (RWGS) reaction to produce CO, and subsequent CO hydrogenation to hydrocarbons via Fischer-Tropsch synthesis (FTS). CO2 is a thermodynamically stable and chemically inert molecule, and RWGS reaction is endothermic and needs a higher temperature, whereas FTS reaction is exothermic and is thermodynamically favored at a lower temperature. Therefore, the reported technologies have some obvious drawbacks, such as high temperature, low selectivity, and use of complex catalysts. Herein we discovered that a simple Co6/MnOx nanocatalyst could efficiently catalyze CO2 hydrogenation. The reaction proceeded at 200 °C, which is much lower than those reported so far. The selectivity of liquid hydrocarbon (C5 to C26, mostly n-paraffin) in total product could reach 53.2 C-mol%, which is among the highest reported to date. Interestingly, CO was hardly detectable during the reaction. The in situ Fourier transform infrared characterization and 13CO labeling test confirmed that the reaction was not via CO, accounting for the eminent catalytic results. This report represents significant progress in CO2 chemistry and CO2 transformation.

Temperature-Dependent Development of Immature Phyllonorycter ringoniella (Lepidoptera: Gracillariidae) and Its Stage Transition Models.

Asiatic apple leafminer, Phyllonorycter ringoniella (Matsumura), is an important insect pest of apple in Northeast Asia. Its larvae mine the leaves and are best managed by targeted sprays. Little is known about its thermal development characteristics, thus, immature P. ringoniella development was investigated under eight constant temperatures (13.3, 15.3, 20.7, 23.6, 26.1, 30.0, 32.3, and 35.0°C) in the laboratory. The total developmental period of the immature stage (egg-pupa) was inversely related to temperature and decreased from 76.4 d at 13.3°C to 25.9 d at 26.1°C. The developmental periods of eggs, larvae, and pupae ranged from 4.8 to 15.2, 15.5 to 40.3, and 5.7 to 21.6 d, respectively. Eggs, larvae, and pupae did not survive at 35.0°C. According to the ordinary linear model, the lower developmental threshold temperatures for egg, larva, pupa, and total immature stage were estimated as 6.7, 6.7, 9.6, and 7.1°C, and the thermal constants as 93.5, 286.5, 94.6, and 480.1 degree-days (DD), respectively. There were large differences among 11 nonlinear models for estimating lower and upper temperature thresholds, and small differences in estimating optimal temperature. Nonlinear temperature-dependent developmental rates were best represented by Lactin-1 model for egg and Briere-1 model for other stages. Stage transition models from eggs to adults of P. ringoniella were constructed by two-parameter Weibull function with the respective selected nonlinear developmental rate models. This study provides a fundamental understanding of thermal traits of P. ringoniella development which will be a useful tool to predict stage transition and for developing decision-based spray timings for integrated pest management.

Impact of probable interaction of low temperature and ambient fine particulate matter on the function of rats alveolar macrophages.

The present study aimed to explore the probable interaction of low temperature and ambient fine particulate matter (PM2.5) on rat alveolar macrophages (AMs). AMs were separated from rat BALF and exposed to PM2.5 (0, 25, 50, 100µg/ml) under different temperature (18, 24, 30, 37°C) for 8h. Results indicated that viability and phagocytosis function of AMs decreased with the decline of temperature and the rise of PM2.5 dose, and the strongest toxicity was shown in the highest PM2.5 (100µg/ml) exposure group at 18°C. Both PM2.5 and lower temperature increased the releasing of tumor necrosis factor alpha (TNF-α), macrophage inflammatory protein 1α (MIP-1α) and interleukin-6 (IL-6), while significant interaction was only found in MIP-1α production. No obvious change was found in granulocyte-macrophage colony-stimulating factor (GM-CSF) detection. These results indicated that both the two factors are harmful to rat AMs and lower temperature could increase the toxicity of PM2.5 on the AMs.

Reliability of Degree-Day Models to Predict the Development Time of Plutella xylostella (L.) under Field Conditions.

The diamondback moth, Plutella xylostella (L.), is a cosmopolitan pest of brassicaceous crops occurring in regions with highly distinct climate conditions. Several studies have investigated the relationship between temperature and P. xylostella development rate, providing degree-day models for populations from different geographical regions. However, there are no data available to date to demonstrate the suitability of such models to make reliable projections on the development time for this species in field conditions. In the present study, 19 models available in the literature were tested regarding their ability to accurately predict the development time of two cohorts of P. xylostella under field conditions. Only 11 out of the 19 models tested accurately predicted the development time for the first cohort of P. xylostella, but only seven for the second cohort. Five models correctly predicted the development time for both cohorts evaluated. Our data demonstrate that the accuracy of the models available for P. xylostella varies widely and therefore should be used with caution for pest management purposes.

Method for Aluminum Oxide Thin Films Prepared through Low Temperature Atomic Layer Deposition for Encapsulating Organic Electroluminescent Devices.

Preparation of dense alumina (Al2O3) thin film through atomic layer deposition (ALD) provides a pathway to achieve the encapsulation of organic light emitting devices (OLED). Unlike traditional ALD which is usually executed at higher reaction n temperatures that may affect the performance of OLED, this application discusses the development on preparation of ALD thin film at a low temperature. One concern of ALD is the suppressing effect of ambient temperature on uniformity of thin film. To mitigate this issue, the pumping time in each reaction cycle was increased during the preparation process, which removed reaction byproducts and inhibited the formation of vacancies. As a result, the obtained thin film had both high uniformity and density properties, which provided an excellent encapsulation performance. The results from microstructure morphology analysis, water vapor transmission rate, and lifetime test showed that the difference in uniformity between thin films prepared at low temperatures, with increased pumping time, and high temperatures was small and there was no obvious influence of increased pumping time on light emitting performance. Meanwhile, the permeability for water vapor of the thin film prepared at a low temperature was found to reach as low as 1.5 × 10-4 g/(m²·day) under ambient conditions of 25 °C and 60% relative humidity, indicating a potential extension in the lifetime for the OLED.

Natural Populations of Drosophila melanogaster Reveal Features of an Uncharacterized Circadian Property: The Lower Temperature Limit of Rhythmicity.

Most cyclic biological processes are under control of a circadian molecular timing system that synchronizes these phenomena to the 24-h day. One generic property of circadian-controlled processes is that they operate within a specific temperature range, below which the manifestation of rhythm ceases. Little is known about the evolutionary relevance of the lower temperature limit of rhythmicity or about the mechanism underlying the loss of overt circadian behavior below this lower limit, especially in one model organism of chronobiology, Drosophila melanogaster. Natural populations of Drosophila are evolving under divergent selection pressures and so provide a source of diversity necessary to address these issues. Using lines derived from African populations, we find that there is natural variation in the expression of rhythmic behavior under low-temperature conditions. We found evidence that this variability is evolutionarily relevant at extremely low temperature (12 °C) because high-altitude populations exhibit selection for locally adapted genomes that contribute to rhythmic behavior. Lines resistant to 15 °C show an additional layer of diversity in their response to temperature extremes because some lines are resistant to low temperature (15 °C) only, whereas others are cross-resistant to high and low temperature (15 °C and 30 °C). Genetic analysis of one cold-resistant circadian line at 15 °C reveals that the phenotype maps to the X-chromosome but not to the core clock genes, per and sgg. Analysis of the central clock cells of this line reveals that maintenance of rhythm is associated with robust clock function, which is compromised in a standard laboratory strain. These data indicate that the cold-resistant circadian phenotype is clock based. This study highlights the importance of using natural populations to inform us of the basic features of circadian traits, especially those that might be under temperature-based selection.

STUDIED ON THE ENRICNMENT OF EPA AND DHA FROM FISH OIL BY LOWER TEMPERATURE CRYSTALLIZATION / 中国海洋药物

The Contents of EPA and DHA were enriched from fish oil by lower temperature crystallization. After first separation,the concentration of EPA and DHA went up to 50%-58% from 7%-15%,and to 73%-79%after sencond separation. The selection of solvents and conditions of crystallization were discussed.

Effects of Temperature on Pratylenchus neglectus and on Its Pathogenicity to Barley.

In a petri-dish study, development of the nematode Pratylenchus neglectus was observed every 4 days, and stage-specific development times were estimated, using a parameter estimation algorithm for a distributed-delay population model. The lower threshold temperature for development of a population of P. neglectus was 7.75 C. Temperatures above 25 C were unfavorable for this population on barley. Total numbers of P. neglectus in barley roots and associated soil in pots were greatest at 25 C and lower at temperatures above and below that level. There was no change in nematode numbers per gram of root as temperature increased between 24 C and 32 C because root weights decreased at higher temperatures. Restricted root mass may contribute to the lower total nematode population levels at higher temperature. Maximum number of nematodes moved through a 2-cm layer of sand on a Baermann funnel at about 20 C; lowest number of nematodes moved at 10 C and 30 C.