Search

The middle Ordovician of Pingliang area on the west margin of North-China platform is represented by a succession of deep-water sediments in which contourites are well-developed. Contour current deposits are well-developed. The contourites can be classified into:calcarenitic contourite, calcisiltitic contourite and calcilutitic contourite. Three typical contourite successions are recognized: complete contourite succession, incomplete contourite succession and contourite successions consisting only of calcarenitic contourites. According to the palaeocorrent and the palaeogeographic format analyse,carbonate contourite drift in the study area is unfolded crossing northwest-southeast, forwarding from southeast to northwest along the slope, and compared with other contourite drifts, it has some characteristics of coarser-grained sediment, thicker individual layers, and highly developed calcarenitic contourites and so on.

A modified phenol-formaldehyde (PF) resin was synthesized under alkaline condition in varying proportion of borax up to 21% (w/w). All the prepared resin were characterized by free phenol content, free formaldehyde content as well as hydroxymethyl content. It was proved by Fourier transform infrared spectrometer (FTIR) that B-O bond had been successfully introduced into the structure of PF resin. Thermo gravimetric analyzer (TGA) and different scanning calorimetry (DSC) were used to characterize the thermodynamic characteristics of the PF resin. The result showed that when the mass fraction of borax was 9wt.% of PF resin, the heat resistance was the best and the curing temperature of the modified PF resin was higher than that of the unmodified PF resin.

In this work, we concentrate on the preparation of oxidized starch modification reagent by enzymatic hydrolysis pretreatment, preparation of the urea-formaldehyde resin with low toxicity. The performance of modified urea-formaldehyde resin depend on the oxidation degree of oxidized starch and whether using enzymatic hydrolysis pretreatment or not. 100-PH9-HOS(the starch enzymatic hydrolysis then oxidized in 100°C with pH 9) synthetized modified urea-formaldehyde resin (100-PH9-HOS-UF) only with a free formaldehyde content of 0.14%, the lowest formaldehyde emission of 0.6078mg/L. Infrared spectroscopy test results show that samples at 3350cm-1 p-hydroxyl hydrogen bonds of association half-peak width minimum hefeng, amino-hydroxy hydrogen bond of association that samples are the weakest and with maximum cross-linking degrees; The modified urea-formaldehyde resin by oxidized starch curing properties of impact factors show that: the deeper drgree of oxidation, the higher curing temperature and the lower enthalpy.

The formaldehyde emission test of MDF decorated with a paper sheet impregnated thermosetting resin was done under the simulated indoor conditions. The results showed that formaldehyde emission decreases after being placed under the condition of high temperature and relative humidity. In addition, the formaldehyde emission of medium density fiberboard with paper impregnated thermosetting resins (MDFPs) increases along with the increase of furniture-bearing ratio.

Simulation of the common application environment of furniture were carried out, effects of different processing methods, storage time and airtight time were investigated. The results showed that the longer storage time or shorter airtight time was, the lower formaldehyde emission was. While the shedding of edge banding and metal connecting parts would increase the formaldehyde emission.

A point-by-point reply is here made to the discussion put forward by G. Shanmugam of our recent paper on internal-wave and internal-tide deposits in the Middle Ordovician Xujiajuan Formation of the Xiangshan Group, Ningxia, China. We readily acknowledge that some issues raised by that author are pertinent. However, others are inconsequential, marginal, disputable, or redundant. The available evidence clearly supports our interpretation that the Middle Ordovician Xujiajuan Formation was deposited in a deep-water setting. Furthermore, we uphold that an internal-wave and internal-tide interpretation for these deposits is plausible in view of the occurrence of bidirectional cross-bedding and unidirectional cross-bedding dipping upslope in a deep-water environment. Also, we consider the request to provide conclusive evidence for the existence of a pycnocline in our stratigraphic record as unreasonable—it is self-evident that these data are currently not available, and the absence of proof is not proof of the contrary.

The curing kinetics of PF resin modified with sodium silicate had been investigated by differential scanning calorimetry (DSC). The kinetic analysis was performed at heating rates of 5, 10, 15, and 20°C/min，respectively. The kinetic parameters such as reaction order and activation energy were solved by Kissinger and Crane equation. The relationship between curing temperature and heating rate was also investigated. The activation energy and the curing reaction order，which were obtained by kinetic calculation, are 83.00kJ/mol and 0.917, respectively. The curing reaction kinetics equations were built by the obtained best curing temperature, reaction order, pre-exponential factor and reaction rate constant.

The novel adhesives were prepared using PF resin as matrix and sodium silicate as modification additive. It was proved by Fourier transform infrared spectrometer (FTIR) that silicon-oxygen bonds had been successfully introduced to the structure of PF resin. Boiling water extraction (BWE)，scanning electron microscopy (SEM)，thermogravimetric analyzer (TGA) and differential scanning calorimetry (DSC) were used to characterize the structure of PF resin modified with sodium silicate (Na2SiO3-PF). The test results show that sodium silicate is an effective modifier to PF resin which lessen the brittleness, accelerate the cure rate and enhance the boiling water resistance of PF resin as well. The FTIR，TGA and DSC test results also show that the structure of PF resin has been changed by sodium silicate.

In order to provide necessary basis for utilization of Anthocephalus chinensis, its chemical composition was explored in this paper. The results as follow: Cold water extractive is 3.18%. Hot water extractive is 4.58%. 1% sodium hydroxide extractive is 18.78%. Alcohol-benzene extractive is 2.73%. Content of cellulose is 44.09%. Content of acid-insoluble lignin is 23.31%.Content of holocellulose is 74.72%. Content of hemicellulose is 30.67%. pH value of wood is 5.31. Through comparing with other species, the results suggested that A. chinensis is ideal material for wood-based panel, interior decoration and packaging.

Fiber and vessel morphology and the radial variation patterns of fast-growing Toona ciliata were studied in this paper. The results showed that the average of cell length, tangential diameter, double wall thickness, length-width ratio, wall thickness-diameter ratio of fiber were 1038.00μm,17.43μm,4.03μm,34.13,0.25 respectively, which of vessel were 313.61μm,123.63μm,6.18μm,1.36,0.05 respectively. The radial variation patterns vary between different characteristics.

Low formaldehyde emission and high bonding strength were two basic criterions of a good urea-formaldehyde resin adhesive (UFRA). In our study, melamine modified methylolurea solution (MUS), was synthesized and used as modifier for UFRA. The bonding strength and formaldehyde emission of urea-formaldehyde resin adhesives(UFRA) were influenced by some factors such as F/U molar ratio of the main resin, F/U molar ratio of modifier, melamine content, mixing ratio of main resin with modifier, which were investigated by a series of single-factor experiments. The results showed that the best adhesive bonding strength of UFRA was 0.93MPa and the lowest formaldehyde emission was 0.43mg / L, when F/U molar ratio of the main resin was 1.5, F/U molar ratio of the MUS was 0.5, the mass fraction of melamine addition level was 5wt.% of MUS, and the mixing mass ratio of methylolurea solution (MUS) to the main UF resin was 20:80.

In this paper, anatomical characters and tissue proportion of fast-growing Toona ciliata samples from Guangzhou was investigated assisted with the light microscope and image analysis system based on the principle of stereology. Qualitative and quantitative data were presented for purposes of identification. Results showed that fast growing T. ciliata was coarse texture with wide growth ring of 3~5cm.The ray proportion was 12.12%-25.56%, the mean value was 17.98%, increasing with time-dependent relevance. The vessel-elements proportion was 6.37%-10.00%, the mean value was 7.40%, increasing then declining and finally increasing. The fiber and other tissue proportion was 67.06%-79.92%, the mean value was 74.62%, declining by year.

Toona ciliata, fast-growing timber species, located in the tropical and subtropical region. In order to explore how to make better use of Toona ciliate, its chemical composition was investigated in this paper. The results show that: Cold water extractive was 1.02%. Hot water extractive was 3.39%. 1% sodium hydroxide extractive was 15.45%. Ethanol-benzene extractive was 1.53%. Content of cellulose was 48.35%. Content of acid-insoluble lignin was 24.92%. Content of holocellulose was 76.45%. Content of hemicellulose was 28.1%. pH value of wood was 6.33. Through comparing with other species, high content of cellulose and low content of extractive suggested that Toona ciliate was ideal material for pulping and board making.

The Xujiajuan Formation of the Lower Xiangshan Group in Ningxia, China, is composed of grayish-green to yellowish-green, fine- to medium-grained sandstone, calcareous sandstone, siltstone, and shale. The upper part is thin-bedded limestone. At the top of the second and third members of the formation, a number of beds intercalated between turbidites and deep-water shale show well-developed cross-bedding. These beds are composed mainly of thin- to medium-bedded calcareous siltstone, fine-grained sandstone, fine-grained calcisiltitic limestone, and silty shale. All bedding types reflect traction-current action. The laminae of the bidirectional and unidirectional cross-bedded units tend to dip either opposite to or at a large angle to the regional slope. The units vary in shape and orientation in both upslope and downslope directions. A comprehensive evaluation of the sedimentary structures and inferred paleocurrents suggests that the cross-bedded intervals were not formed by contour currents or turbidity currents, but most probably represent internal-wave and internal-tide deposits.

The phenol-melamine-urea-formaldehyde (PMUF) cocondensed resin adhesive was prepared by using phenol, urea, melamine and formaldehyde as reactants. It was characterized by 13C NMR and the results indicated that the PMUF could reduce the content of free formaldehyde, and it could make wood-based panel with high water resistance and weatherability. Sodium carbonate (Na2CO3) was able to shorten the curing time by 40% when applied to the plywood process. The addition of Na2CO3 as the curing accelerator of a PMUF had little influence on the bonding strength of waterproof layer and could shorten the hot-press time.

Hexamethoxymethyl melamine (HMMM) was used to modify UF resins to obtain good performance with low formaldehyde emission. The effect of urea to formaldehyde ratio, HMMM content on the properties of UF resin was studied in detail. The results suggested that urea to formaldehyde ratio to be 1:0.9 and 20% HMMM content is the optimum formulation to afford desired UF resin. The viscosity, solidification time, bond strength and formaldehyde emission of the modified UF resins were also studied. The results revealed that the performance of the modified UF achieved the chinese standard.

The study of internal-wave and internal-tide deposits is a new research field on sedimentology during the last ten years. Deep-water traction currents induced by internal waves and internal tides are developed on the modern sea floor, which can form not only all kinds of small scale and dispersal deepwater traction currents deposits, but also large-scale sediment wave in km-size scale. In this paper, the concepts and features of internal waves and internal tides in oceanography are introduced, and the characteristics, sedimentary sequences, sedimentary microfacies and sedimentation models of internal-wave and internal-tide deposits found and the origin of large scale sediment waves in deep sea bottom are summarized. The relationship between internal-wave and internal-tide deposits and petroleum is discussed, and finally internal-wave and internal-tide deposits are shown to be a new potential field for petroleum exploration.

Five hardwood species (Schima superba Gardn, kapur( Dryobalanops sp.), ash (Fraxinus mandshurica Rupr.), birch(Betula platyphylla Suk.), tauari (Couratari sp.)) were conducted the Heat treatment at 185°C.. The results indicated that the dimensional stability, modulus of elasticity (MOE) increased greatly while the wettability decreased after treatment. There was a negative impact of heat treatment on MORs.

Publisher Summary Sediment entrainment refers to the processes by which contour currents capture and transport sediments. This chapter describes the processes that are potentially capable of delivering similar sediments to contour-current systems. Sediment entrainment for contourites is mainly based on theoretical interpretation and on speculations regarding sedimentary features of modern and ancient contourites including grain size, components, textures, and structures––in terms of fluid hydrodynamics of possible flows operating in oceans. The mechanisms of sediment entrainment processes are categorized based on sedimentary textures, structures, and components of various contourites, as well as on their spatial variation. The most important mechanisms for sediment entrainment in contourites are: (1) the resuspension from bottom currents or benthic storms, (2) sediment density flows––including turbiditic and hyperpycnal flows, (3) micro-bioclastics-forming processes, (4) volcanic, (5) glacial activity, and (6) burrowing. Bottom currents resuspend or rework the sediments on their pathways. Gravity flows deliver both fine and coarse sediments to the pathways of contour currents. Bioclastics-forming processes provide bio-skeletons or fragments to contourites. Volcanic and glacial processes provide significant amounts of sediments to contour currents in some special situations. Bioactivity that can resuspend sediments is less significant in most cases.