Effects of log position in the stem and commercial thinning on jack pine chip dimensions produced by a chipper-canter

Fifteen stems of jack pine (Pinus banksiana Lamb.) coming from three commercial thinned (CT) plots (control, moderate, and intensive thinning) in the Abitibi-Témiscamingue region, Canada, were cross-cut into three 2.4 m length sections: bottom, middle, and top logs. Logs were processed with a chipper-canter at three cutting widths (CW 12.7, 19.1, and 25.4 mm), producing chips and a three faced cant. Chips were assessed by thickness, width, and length. Knot characteristics [total knot number (TKN) and area (TKA)] were assessed in the three cant faces. Growth ring attributes [earlywood density, latewood density (LWD), ring density (RD), earlywood proportion (EWP), ring width, and rings per mm], mechanical properties (shear, splitting, modulus of elasticity and modulus of rupture in bending), and basic density were evaluated on samples obtained within each CW area. The weighted mean chip thickness (WCT) was significantly affected by the log position in the stem (LPS) and CW. WCT increased as CW increased. Jack pine produce thicker chips than black spruce, when processed under the same cutting parameters. Thickness of chips coming from bottom and middle logs was similar due to a greater taper of the bottom log, which slightly increased this dimension. Thickest chips were produced in the top log due to a higher TKA and TKN towards the top of the stem. Multiple linear regressions showed that TKA, CW, and RD were significant predictors of WCT. Chip size distributions were significantly affected by the CT, LPS, and CW. Thinned stands logs appeared to produce smaller chips than natural stand logs. Moreover, chip thickness distribution was affected primarily by TKA and EWP, while the width and length distribution was mainly affected by EWP, LWD, and TKN. Chip size in jack pine is to some degree determined by knot attributes, growth ring characteristics, and wood density of the raw material. These results suggest the potential advantage of sorting logs prior to chipping, either by species, LPS and/or provenance (thinned or natural stands).     

Heat transfer computation for a long,frozen log heated in agitated water or steam—a practical recipe

This paper presents, step by step, an exemplary computation of transient temperature as a function of heating time for a log that was initially frozen and is heated in agitated water or steam. An unfrozen log heating situation can be handled likewise and is less complex. Log length must be at least four log diameters for this method to work correctly. The method, based on an enthalpy approach with finite-difference technique, can be computerized and applied for parametric studies and process control in veneer- and plywood mills, waferboard mills, etc.     

Use of round wood of chestnut tree coppices: crack risk and effects of a hot oil bath treatment

The chestnut tree (Castanea sativa Mill.) presents good mechanical properties, when valorised in the form of round wood in small diameter. On the other hand, it is very sensitive to cracking during drying. The topic of this study is to optimize a hot oil bath treatment known from previous studies to reduce surface checking. Here, we compare the state of cracks of two series of chestnut tree logs: one is directly dried to 12% moisture content (MC), the other one is treated for one hour using a 130 °C oil bath first, then dried to 12% MC. This first experiment led us to study the evolution of the temperature in the log during the treatment and to propose a chart to determine treatment time in a 130 °C bath. This chart has been successfully tested on a second series of logs.     

The Effects of High-Pressure Processing at Low and Subzero Temperatures on Inactivation of Microorganisms in Frozen and Unfrozen Beef Mince Inoculated with Escherichia coli Strain ATCC 25922

Frozen and unfrozen beef mince inoculated with Escherichia coli strain ATCC 25922 were exposed to a pressure of 300 MPa for 5 min at different temperatures (?10, ?5, 0, 10 and 20 °C). A maximum reduction of 1.5 log in total aerobic count (TAC) was obtained in unfrozen samples at ?5 °C, whereas at 20 °C, the reduction was only 0.6 log. Microbial inactivation in beef mince was enhanced by freezing the beef mince prior to pressurization. An average log reduction of 3.0 (SD?=?0.2) in both E. coli and TAC was obtained in frozen beef mince treated at ?5 °C. The highest bacterial reductions were observed in frozen samples. The extent of bacterial injury was substantially less in frozen samples than unfrozen samples, indicating that the damage inflicted on microorganisms in frozen beef mince by high pressure was irreversible. Lightness (L ^*), redness (a ^*) and yellowness (b ^*) values measured in accordance of Commission Internationale de l’Eclairage (CIE) for all the pressure-treated frozen and unfrozen samples differed slightly from unfrozen control samples (average total colour change, ΔE?=?6.1, SD?=?1.1). Water-holding capacity (WHC) measured by “high-pressure expressed moisture”, a new method proposed in this study, showed that freezing the samples prior to pressurization could increase WHC of minced beef. The results suggest that high-pressure processing could be used to make safer traditional raw minced meat products, such as steak tartare and cig kofte, a traditional Turkish dish made with minced beef, bulgur and spices.     

木浆生产线的备木技术

介绍了当前广泛应用的备木生产线中原木剥皮、削片、木片筛选、过大木片再碎、木片贮存、树皮及木屑处理以及原木冲洗等系统的特点,通过分析不同剥皮鼓的喂料及卸料方式、不同削片机的喂料及卸料方式以及各种备木生产设备运行的情况,对备木设备的改进以及设备布置的方式提出了一些建议。     

Impact of Aspen Log Storage with and without Protection on OSB Performance

Outdoor log storage without protection can change the mechanical and chemical properties of wood due to infection by various fungi. To understand how outdoor log storage affects the wood and, subsequently, the strandboard quality, two piles of aspen logs were set up outside and stored for a period of four months (July to November). One of the piles was treated with a biological solution to prevent fungal growth. The other one was stored without treatment. Both piles contained non-debarked and partially debarked logs. Evaluation of sap stain development indicated that all logs had been colonized by staining fungi with average stain coverage of 9.37 to 57.18% and maximum stain penetration of 3.58 to 7.27 cm over the log cross section. The variation of fungal colonization depended on log treatment and bark condition. The most effective way to prevent stain growth was the combination of biological treatment and partial debarking. A series of strandboard was prepared from fresh and aged aspen logs. All boards made from stored logs were statistically comparable to or superior to the control boards made from fresh aspen logs. The boards made from treated/partially debarked and untreated/non-debarked logs were statistically comparable to each other except for wet MOR. In addition, these two board types were statistically stronger than other boards made from treated/non-debarked and untreated/partially debarked logs in terms of IB and water resistance. Some individual stained strands were observed on the finished board surface. Less staining was found in the boards prepared from biologically treated and partially debarked logs, compared with those made from other stored logs.     

Double-sided pan-frying of unfrozen/frozen hamburgers for microbial safety using modelling and simulation

The predictive mathematical heat and mass (water and fat) transfer models for the double-sided pan-frying of unfrozen and frozen hamburger patties were developed and validated against experimental data. The simulation results demonstrated the inactivation of Escherichia coli O157:H7, Listeria innocua, and Salmonella serotypes within patties during cooking. The effects of various patty thickness and pan temperature on safe process time were analyzed. For a safe patty, double-sided pan-frying with 160 °C pan temperature is recommended due to its faster cooking and better microbial safety. The cooking times for double-sided pan-frying of frozen and unfrozen patties are approximately 293 and 115 s, respectively. The increase in heating temperature resulted in higher rates of patty centre temperature increase and water and fat losses, and decreased the process time for 12 log reductions of microorganisms. An increase in the thickness of the patty resulted in an increased process time.     

Relationship Between Static Electrical Conductivity and Unfrozen Water Content in Food Products

The static electrical conductivity measurements on frozen foods such as citrus juice and varieties of cheese showed that both conductivity and unfrozen water content in food products varied directly with temperature. In describing the log σ vs 1/T curve, where σ is the conductivity and T is the absolute temperature, it was found that the linear portion of the curves at low temperature was related to bound water content which was independent of temperature, whereas the non-linear portion in the temperature range between the freezing point and 10 or 35 degrees below the freezing point was related to the unfrozen free water content which was dependent on temperature.     

国产大型木片洗涤系统的配套设计与生产运行

国内某厂的木片杂质含量较高,并由于贮存时间过长,木片部分纤维腐烂变质。通过配套国产木片洗涤系统,在设计能力2100t/d下砂石的洗涤去除率达80%左右;在1200t/d的生产能力下沙石的洗涤去除率达90%左右,使木片含砂率降低到0.03%左右,且去除了部分腐朽变质的纤维。经洗涤水槽沉淀后洗涤水的循环利用率为60%左右。     

Befall länger beregneten Fichtenstammholzes durch Hallimasch (Armillaria spp.) und sonstige Holzpilze

The quality of water-sprinkled spruce logs from 42 different Bavarian storage sites and the accompanying fungal flora were examined after four years of storage. It was found that — except for special cases — rot in the sapwood has to be generally expected after four years causing severe economical damage. This is contrary to the opinion generally accepted so far. The damage, however, remains restricted to the sapwood. Significant reductions in strength properties occurred only in heavily discoloured areas. Obviously the fungus prefers the inner climate of the log stack, because the infection was concentrated on the middle parts of the logs. Apart from the log ends also the top and side logs of the stack were mostly free from attack. Different factors influencing the infection are discussed. For example it could be shown that even very well sprinkled stacks were attacked, because the fungus is able to cause decay in very moist wood. Incorrect water sprinkling causes additional attack by other wood-destroying Basidiomycetes. No infection was observed in storage sites above 1000 meters altitude. Also a small stack of debarked logs proved to be free of fungi. Consequences for practical application derived from these results are being discussed.     

Roundwood pre-grading with longitudinal acoustic waves for production of structural boards

The assessment of timber quality at any stage of the production chain promises to be an advantage for the forest and timber industry. This paper presents results of wood pre-grading by means of the dynamic modulus of elasticity, which was performed along the complete processing chain—from standing trees to sawn timber. The measurements were conducted on 154 forty-year-old trees of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) from two forest experimental stands in Southern Germany. Long logs of about 13 m were bucked into short logs of 4.1 m; the dataset contained 1,820 boards cut out of 332 short logs. Pre-grading was performed at different levels: standing tree, long log, and short log. The boards were machine strength graded by a ViSCAN-COMPACT grading machine. The investigation showed high correlations between different stages in the production chain of timber. For strength classes C24 and C30 an increase in yield of about 10 percentage points by rejecting the 25 % worst logs (short or long) was observed. It did not matter if pre-grading was realized at the stage of long logs or short logs. However, methods of pre-grading at standing tree must be improved to obtain reliable prediction of dry sawn timber quality of managed forest stands (r² = 0.17).     

Evaluating vacuum and steam process on hardwood veneer logs for export

There is an immediate need to develop and adopt new treatment technologies for eliminating insect pest and tree pathogens from veneer logs moved in trade. This is largely due to the current phase-out of methyl bromide and the uncertainty associated with the efficacy of potential alternatives. Vacuum and steam in combination has a proven and reliable record for commercially sanitizing a variety of commodities, including cotton, spices and textiles among others. This study was designed to evaluate basic parameters of vacuum and steam application on five high value hardwood veneer log species in an effort to ascertain the feasibility of continued treatment development. Relative heating rates to log center, damage and value loss assessment due to treatment, and overall energy used during treatment were recorded for logs treated individually in a flexible polymer chamber. At 200 mm Hg vacuum, time to reach 56 °C for 30 min to core ranged from 17 to 29 h, depending on density and log diameter. End checking varied by species, but veneer sawn from logs was largely unaffected in terms of yield and value. Energy used during treatments ranged from 54 to 205 kWh for individual logs. Results suggest that vacuum and steam as a phytosanitary treatment for hardwood veneer logs has potential and should be explored further.     

Effect of microwell chip structure on cell microsphere production of various animal cells

The formation of three-dimensional cell microspheres such as spheroids, embryoid bodies, and neurospheres has attracted attention as a useful culture technique. In this study, we investigated a technique for effective cell microsphere production by using specially prepared microchip. The basic chip design was a multimicrowell structure in triangular arrangement within a 100-mm² region in the center of a polymethylmethacrylate (PMMA) plate (24 × 24 mm²), the surface of which was modified with polyethylene glycol (PEG) to render it nonadhesive to cells. We also designed six similar chips with microwell diameters of 200, 300, 400, 600, 800, and 1000 μm to investigate the effect of the microwell diameter on the cell microsphere diameter. Rat hepatocytes, HepG2 cells, mouse embryonic stem (ES) cells, and mouse neural progenitor/stem (NPS) cells formed hepatocyte spheroids, HepG2 spheroids, embryoid bodies, and neurospheres, respectively, in the microwells within 5 days of culture. For all the cells, a single microsphere was formed in each microwell under all the chip conditions, and such microsphere configurations remained throughout the culture period. Furthermore, the microsphere diameters of each type of cell were strongly positively correlated with the microwell diameters of the chips, suggesting that microsphere diameter can be factitiously controlled by using different chip conditions. Thus, this chip technique is a promising cellular platform for tissue engineering or regenerative medicine research, pharmacological and toxicological studies, and fundamental studies in cell biology.     

Lose Dämmstoffe aus Holz – Wärmeleitfähigkeit von speziell hergestellten Fräßspänen ausgewählter Holzarten

The thermal conductivity of loose-fill thermal insulation materials based on optimized milling chips made of different wood species was investigated at a variety of densities. The produced chips have the same geometry and very much the same particle size distribution. If the volume of the chips itself is the same, the specific anatomy of the wood only influences the density of the particle system, the thermal conductivity, however, remains unchanged.     

Factors dominating adhesion of NaCl onto potato chips

ABSTRACT:  In this study, the adhesion factors examined were time between frying and coating, surface oil content, chip temperature, oil composition, NaCl size, NaCl shape, and electrostatic coating. Three different surface oil content potato chips, high, low, and no, were produced. Oils used were soybean, olive, corn, peanut, and coconut. After frying, chips were coated immediately, after 1 d, and after 1 mo. NaCl crystals of 5 different particle sizes (24.7, 123, 259, 291, and 388 μm) were coated both electrostatically and nonelectrostatically. Adhesion of cubic, dendritic, and flake crystals was examined. Chips were coated at different temperatures. Chips with high surface oil had the highest adhesion of salt, making surface oil content the most important factor. Decreasing chip temperature decreased surface oil and adhesion. Increasing time between frying and coating reduced adhesion for low surface oil chips, but did not affect high and no surface oil chips. Changing oil composition did not affect adhesion. Increasing salt size decreased adhesion. Salt size had a greater effect on chips with lower surface oil content. When there were significant differences, cubic crystals gave the best adhesion followed by flake crystals then dendritic crystals. For high and low surface oil chips, electrostatic coating did not change adhesion of small size crystals but decreased adhesion of large salts. For no surface oil content chips, electrostatic coating improved adhesion for small salt sizes but did not affect adhesion of large crystals.     

Value optimized log rotation for strength graded boards using computed tomography

A possible application for an industrial computed tomography scanner in a sawmill is finding an optimal rotational position of logs with respect to knots and outer shape. Since a computed tomography scanner is a great investment, it is important to investigate potential profitability of such an investment for different production strategies. The objective of this study was to investigate the potential value increase of the sawn timber of Norway spruce (Picea abies (L.) Karst.) by rotating logs to their optimum position prior to sawing compared with sawing all logs in horns down position. The production strategy evaluated by log breakdown simulation in this case study was to produce strength graded timber of the center boards, while the side boards were appearance graded. This case study showed an average value increase with respect to the value of center boards, side boards and chips of 11 %.     

The influence of material properties on the amount of twist of spruce wood during kiln drying

The development of twist in Norway spruce boards (Picea abies Karst.) during normal temperature kiln drying was researched. Tangentially oriented boards were sawn from diametrical radial planks, from which the basic wood properties, i.e. linear shrinkage and grain angle, were determined. The unrestrained boards were kiln dried using a selected drying schedule. During the controlled drying process the moisture content (MC) and twist of the boards were measured. Twist was generally induced by the shrinkage of wood below the fibre saturation point, and increased in proportional to the decrease in MC. The earlier appearance of twist, with regard to MC and drying time, was confirmed in the case of boards sawn from the central part of logs. The final twist amounted to between 10 and 20°/m in the case of boards close to the pith, and decreased to less than 4°/m in the case of boards sawn at a radius of 70 mm from the centre of the logs. Ring curvature had the highest impact on the final twist of the dried boards, followed by grain angle and tangential shrinkage.     

国内速生桉木木片质量对制浆性能的影响

对国内速生桉木影响硫酸盐法制浆性能的几个因素进行了探讨,着重讨论了过厚片、木片长度、木芯片、树种及木材生长年限等对蒸煮得率和成浆质量的影响。     

Effects of log storage conditions and steaming process on the formaldehyde emissions of particleboard manufactured from eucalyptus (E. camaldulensis) wood

The aim of this study was to determine the changes in formaldehyde emissions of eucalyptus particleboards produced from logs stored under different conditions (indoor, outdoor, and under water) or steamed. The pH and Stiasny values of particles changed significantly according to the storage condition and log steaming process. The pH values of particles obtained from steamed logs and stored outdoors for 4 months were found to be lower than those of the particles obtained from logs stored in the other aforementioned two conditions. The peaks of acetyl groups in the IR-spectra of the four group particles were similar. There was a strong relationship among the formaldehyde emission values of the panels pressed at 150 °C and the Stiasny values of the particles from which the panels were produced. The formaldehyde emission values of the panels pressed at 190 °C were lower than those of the panels pressed at 150 °C.     

Properties of Starch Obtained from Frozen and Thawed Potato Tubers

Starch separated from frozen potato tubers differed from that separated from unfrozen material in the initial pasting temperature and viscosity of 7% pastes. The starch separated from frozen and thawed potato tubers was characterized by higher temperatures of pasting than starch obtained from unfrozen potato tubers. Moreover, it showed some differences in granularity, phosphorus, calcium, sodium and potassium content as well as viscosity of 7% pastes in comparison with starch obtained from unfrozen potato tubers.