Layers Of Aluminum Foil Research Articles

Alkyl ketene dimer (AKD) sizing of paper under simplified treatment conditions

Alkyl ketene dimer (AKD) has been widely used by manufacturers of paper and paperboard as a hydrophobic sizing agent. Ordinary sizing with AKD involves a complex series of processes, including emulsification of the waxy AKD material; measures to avoid the agglomeration of the emulsified AKD particles; addition of a stabilized AKD dispersion to papermaking furnish; interactions with various retention aid chemicals to fix the material onto solid surfaces; and various spreading and curing processes that take place during the drying and cooling of the paper product. In the present work, as a means to gain insight into the mechanisms attributable only to the AKD in isolation from the other additives and subprocesses, the AKD wax was dissolved in heptane and applied to filter paper between two aluminum foil layers, followed by evaporation of the solvent and optional heating. Surprisingly, hydrophobic character was obtained regardless of whether or not the treated sheets had been heat cured. Also, for the first time, it was observed that the AKD treatment resulted in a substantial increase in sheet strength, suggesting that the AKD was able to serve as the matrix in an AKD-saturated paper structure. The results add support to past suggestions in the literature that potential covalent interactions cannot account for all of the effects attributable to AKD treatment of paper.

Thickness-controllable electrospun fibers promote tubular structure formation by endothelial progenitor cells.

Controlling the thickness of an electrospun nanofibrous scaffold by altering its pore size has been shown to regulate cell behaviors such as cell infiltration into a three-dimensional (3D) scaffold. This is of great importance when manufacturing tissue-engineering scaffolds using an electrospinning process. In this study, we report the development of a novel process whereby additional aluminum foil layers were applied to the accumulated electrospun fibers of an existing aluminum foil collector, effectively reducing the incidence of charge buildup. Using this process, we fabricated an electrospun scaffold with a large pore (pore size >40 μm) while simultaneously controlling the thickness. We demonstrate that the large pore size triggered rapid infiltration (160 μm in 4 hours of cell culture) of individual endothelial progenitor cells (EPCs) and rapid cell colonization after seeding EPC spheroids. We confirmed that the 3D, but not two-dimensional, scaffold structures regulated tubular structure formation by the EPCs. Thus, incorporation of stem cells into a highly porous 3D scaffold with tunable thickness has implications for the regeneration of vascularized thick tissues and cardiac patch development.

First Report of Chrysoporthe deuterocubensis Causing Canker on Syzygium samarangense in Taiwan.

Wax apple (Syzygium samarangense Merr. & Perry, syn. Eugenia javanica Lam.) belongs to the Myrtaceae family is an important economical tree fruit in Taiwan. The total production acreage of wax apple was 5,266 ha in which more than 77% were located in Pingtung County, southern Taiwan, in 2012. Since the winter of 2010, symptoms of withering leaves and cracking branches on wax apple trees were observed in some orchards in Nanjhou and Linbian Townships, Pingtung County. Diseased trees declined gradually and resulted in reduced fruit production. On the bark of diseased twigs and branches, black conidiamata with yellowish orange conidia were usually observed. For diagnosis, tissues from symptomatic branches were excised, surface sterilized with 0.5% sodium hypochlorite, and placed on 2% water agar in petri dishes. A total of four identical fungal isolates were obtained and maintained on potato dextrose agar (PDA). To fulfill Koch's postulates, three twigs of a wax apple tree were wounded with scalpel and inoculated with each of the four isolates, one tree per isolate. A 7-day-old hyphal mat (about 7 × 18 mm) of each fungal isolate was attached on the wound, wrapped with a wet absorbent cotton and Parafilm, and then covered with a layer of aluminum foil. For the control, the twigs of a wax apple tree were inoculated with PDA plugs. The pathogenicity test was repeated once. After 30 days, withering leaves and cracking twigs were observed on inoculated twigs and the same pathogen was reisolated. Conversely, all of the non-inoculated plants remained healthy. Identification of the pathogen was conducted using its morphological, physiological, and molecular characteristics. On malt extract agar, the colony was floccose and white with hazel hues. The optimal temperature for the mycelial growth was 30°C. Conidia were hyaline, and oblong, with the average size of 4.7 ± 0.6 × 2.7 ± 0.2 μm (100 conidia). Ascostromata were semi-immersed in the bark with fusoid asci, eight ascospores per ascus. Ascospores were hyaline, 2-celled, and tapered in both ends, with the average length of 6.8 ± 0.7 × 2.4 ± 0.3 μm (100 ascospores). For molecular identification, the internal transcribed spacer (ITS) of ribosomal DNA and β-tubulin genes was amplified using the ITS1/ITS4 (3), Bt1a/Bt1b, and Bt2a/Bt2b (1) primer pairs. The gene sequences were deposited in GenBank (Accessions KC792616, KC792617, KC792618, and KC792619 for the ITS region; KC792620, KC792621, KC792622, and KC792623 for Bt1 region, and KC812732, KC812733, KC812734, and KC812735 for Bt2 region) and showed 99 to 100% identity to the Chrysoporthe deuterocubensis isolate CMW12745 (DQ368764 for ITS region; GQ290183 for Bt1 region, and DQ368781 for Bt2 region). In addition, the Bt1 region of the β-tubulin gene consisted of two restriction sites for AvaI and one restriction site for HindIII. This is identical to the description of C. deuterocubensis, a cryptic species in C. cubensis, by Van Der Merwe et al. (2). According to these results, the pathogen was identified as C. deuterocubensis Gryzenh. & M. J. Wingf. To the best of our knowledge, this is the first report of canker disease caused by C. deuterocubensis on S. samarangense in Taiwan.

SU-E-T-109: Calypso RF Interference On Portal Images and a Physical Filter Solution

Purpose: Portal measurement is becoming an important tool for in vivo dosimetric verification, and Calypso provides real‐time tracking capability; however, when both work simultaneously, large interference arises for portal measurement. The purpose of this study is to investigate the interference of Calypso on portal measurement and mitigation of the interference by applying aluminum shielding over portal panels. Methods: For the same IMRT field and phantom setup, we acquired portal measurements at every 15 degree gantry angle, without and with Calypso, and for those measurements with Calypso, we also acquired portal measurements without and with aluminum shielding over the portal panels. The aluminum shielding consists of a layer of aluminum foil of 0.1 mm thickness covering the portal panel. The measurements without Calypso and without aluminum shielding were regarded as the reference images. All other measurements were regarded as the test images. We measured the deviation of the test images from the reference images by the amplitude difference and using the Gamma Index (3%, 3 mm). Results: With Calypso interference and without aluminum shielding, the signals are larger than the reference, and in some unfavorable gantry angles, the signals can be as much as 15% larger. With aluminum shielding, the interference was much reduced to ∼3% for those unfavorable angles, and the Gamma passing rate achieves 95% for most of the angles. Conclusion: The Calypso interference on portal measurements is gantry angle dependent due to panel orientation and proximity with respect to the Calypso transducer. Shielding on the portal panel can largely reduce electronic interference, and it is anticipated that with an improved complete shielding over the entire portal panel, the interference could be further reduced.

EFFECT OF PACKAGING MATERIALS ON QUALITY OF ORANGE JUICE

Refrigerated orange juice was packed in four different refills, three of them made of cardboards with different composition and the fourth from polyethylene terephthalate transparent. The four refills were stored at 4 °c for 75 days, during the storage of juice, changes in the headspace gas composition, vitamin C, and color. In addition , the sensory evaluation of arbitrators for both color, flavor and unwanted odors. Experimental data indicated that the deterioration of orange juices (ascorbic acid degradation and darkening of color) was triggered by the rise in oxygen in the headspace of the storage refills. The type of refill played a predominant role in determining the juice quality, with carton refills with an inner layer of aluminum foil providing the juices with the best quality throughout their storage.

Efficacy of reflective insulation in reducing heat stress on dairy calves housed in polyethylene calf hutches

The objective of this study was to determine the ability of radiant insulation hutch covers to moderate the effect of ambient temperature and radiant energy on calves housed in polyethylene hutches. The insulation had a double layer of polyethylene bubble film laminated between a layer of aluminum foil and white polyethylene (reflectance = 95%, R value (ft(2) · °F ·h/Btu) = 2.7). In each of two experiments (exp.), hutches were either uninsulated (control) or covered with reflective insulation across the top and sides of the hutch leaving the front, back, and pen exposed. Each hutch had a 1.2 × 1.8-m attached outdoor wire pen. In both exp., rate of increase of interior hutch temperature relative to ambient temperature was lower in insulated hutches (P < 0.001) indicating they were warmer at low THI and cooler at high THI. In exp. 1, increase in respiration rate and ear canal temperature of the calves, relative to THI, were moderated in insulated hutches (P < 0.001). In Exp. 2, respiration rate was not affected by treatment (P = 0.50), but increased with increasing THI (P < 0.001). Mean ADG did not differ among treatments in either exp. (P > 0.21). Insulating calf hutches with reflective insulation moderated hutch microclimate, and improved calf comfort, but did not translate to improvements in economically relevant variables such as ADG.

Quantitative analysis of the damping of magnet oscillations by eddy currents in aluminum foil

This paper considers damped rotational oscillations about the vertical axis of a cylindrical permanent magnet that is horizontally suspended by a vertical inelastic thread. The damping of the oscillations is caused by eddy currents induced in aluminum foil that is placed horizontally below the magnet. A simplified mathematical model of the damped oscillations is proposed and verified by experiment qualitatively and quantitatively. It is shown that the relative energy loss during one oscillation depends linearly on the number of layers of aluminum foil and on the oscillation period. To measure the relative changes of the oscillation amplitude, a magnetic field sensor and data collection interface are used.

Ignition of Contaminated Aluminum by Impact in Liquid Oxygen—Influence of Oxygen Purity

Abstract Impact tests in liquid oxygen and oxygen enriched liquids have been conducted on aluminum foils (0.2 mm thick) used for heat exchangers of air separation units (ASUs). Some adaptations to the ASTM Standard D2512, “Standard Test Method for Compatibility of Materials with Liquid Oxygen,” have been done to ensure the good control of oxygen content in the cryogenic liquid and to get reproducible results in aluminum ignition with hydrocarbon coating. Modified striker pins with a cavity on the contact surface have been used. The vertical guiding and the centering of the striker pins have been ensured by using two machined guides. Test samples were three layers of aluminum foil, two corrugated and one flat, contaminated by various quantities of hexadecane. The criteria for the identification of aluminum ignition (positive tests) have been validated by performing Scanning electron microscope surface analysis on residuals of a few impact tests performed in copper cups. Criteria have also been defined to check that hexadecane combustion took place in negative tests. A sufficient number of tests have been performed to plot the probability of ignition of the aluminum samples as a function of the average thickness of hexadecane coating and as a function of the oxygen content in the cryogenic liquid varying from 50 % to above 99.95 %. The remaining part in the cryogenic liquid was nitrogen and 2.3 % argon except for one series of tests where the influence of the absence of argon could be identified. The results of these tests can be used to assess the risk of ignition of some aluminum exchangers or structures used in ASU.

EFFECT OF PACKAGING MATERIALS ON COLOR, VITAMIN C AND SENSORY QUALITY OF REFRIGERATED MANDARIN JUICE

ABSTRACT Refrigerated mandarin juice was packed in four different containers, three cartons with different composition and one polyethylene terephthalate transparent bottle, and was stored at 4C for 90 days. During the storage of these juices, changes in the headspace gas composition, vitamin C, and CIE L*, a* and b* color coordinates were evaluated. In addition, a consumer panel evaluated the sensory color, fresh mandarin flavor and presence of off‐flavors in the juices. Experimental data indicated that the deterioration of mandarin juices (ascorbic acid degradation and darkening of color) was triggered by the rise in oxygen in the headspace of the storage containers. The type of container played a predominant role in determining the juice quality, with carton containers with an inner layer of aluminum foil providing the juices with the best quality throughout their storage.PRACTICAL APPLICATIONSResults from this study will provide manufacturers of mandarin juice with information dealing with the storage and quality of juices packed in different containers. In this way, if manufacturers want to use transparent polyethylene terephthalate (PET) bottles showing the color and appearance of the juice, they will be aware that the shelf life of the juice will be much shorter than in packed cartons; this reduction will be from more than 90 to 36 days (PET bottle). On the other hand, if manufacturers want to use carton for their packaging, they will be aware that using a container with a thick inner layer of aluminum foil will maintain the quality of the juice for a longer time (over 90 days) compared with a shelf life of about 54 days from cartons with an inner layer of ethylene vinyl alcohol copolymers.

Initiation of a reaction in aluminum-Teflon multilayer thin-film samples by drop-hammer impact loading

Experimental results on the initiation of samples composed of alternating layers of aluminum foil (0.65, 4, 10, or 20 μm in thickness) and Teflon films (20 or 50 μm) by drop-hammer impact loading are presented. In contrast to powdery mixtures, lamellar compositions have a rigorously controlled surface area of contact of the interacting components. The light flash signifying the event of initiation and the impact pressure were recorded with a photodiode and a tensiometer, respectively. It was established that, under typical condition of initiation of HEs, the aluminum-Teflon lamellar samples are deformed as brittle materials. At a certain pressure, after the stage of elastic compression, a rapid disintegration (within 30 μs) with the formation of local reaction initiation sites at shear surfaces of individual segments occurs. The results obtained are indicative of the mechanochemical nature of the interaction between aluminum and Teflon layers under impact loading conditions.

In vitro micropropagation and ex vitro acclimation of Bupleurum kaoi-an endangered medicinal plant native to Taiwan

Summary This study reports an improved protocol for in vitro-shoot multiplication and ex vitro acclimation of Bupleurum kaoi ,a n endangered medicinal herb. Nodal segments were cultured in half-strength Murashige and Skoog (MS) basal medium supplemented with different concentrations of benzyladenine (BA) and kinetin. The presence of 0.25 mg l 21 BA induced the highest number of shoots per explant after 8 wk of culture. Although BA was more effective than kinetin on shoot multiplication, it induced hyperhydric shoots at all concentrations tested. The use of dispense paper (DP) instead of aluminum foil (AF) for container closure was found to reduce hyperhydricity and improve ex vitro acclimation. The best survival rate (61%) was obtained when plantlets were grown in MS basal medium containing 0.5 mg l 21 indole-3-butyric acid and 0.1– 0.2 mg l 21 a-naphthaleneacetic acid using DP as container closure. Leaves of the plant treated with AF6 (two layers of AF as container closure and 6 wk of incubation) lacked epicuticular wax and possessed larger stomata, higher stomata density, and fewer functional stomata compared to those of plants treated with AF2 þ DP4 (two layers of AF for 2 wk, then replaced AF by three layers of DP for 4 wk) and ex vitro-acclimated plantlets.

Thermomechanical Analysis of an Ultrasonic Rapid Manufacturing (URM) System

Ultrasonic rapid manufacturing (URM), a low-temperature solid freeform fabrication method capable of producing high-strength functional solid metal parts and multi-material composites, is based on ultrasonic welding (USW) of metals. The quality of the weld, a critical aspect of the URM process, depends on (a) the amount of mechanical energy applied, through an appropriate combination of welding parameters: vertical pressure, horizontal vibration frequency, amplitude, and welding time, (b) the resulting heat generation, and (c) temperature rise. This paper investigates the thermomechanical process aspects and provides insight into the heat generation and transient-temperature profile during a single weld cycle under the special welding conditions developed in this article and validated in the laboratory. The finite element model analysis of two layers of aluminum foil subjected to these welding conditions—with surface contact resistance calibrated by experiments—reveals a moderate temperature rise but one that is sufficient for metal bonding via vacancy diffusion.

GLASS TRANSITION TEMPERATURE OF RICE KERNELS DETERMINED BY DYNAMIC MECHANICAL THERMAL ANALYSIS

A protocol was developed to measure the glass transition temperature (Tg) of brown rice kernels using dynamicmechanical thermal analysis (DMTA). In order to accommodate the sample requirements of the dynamic mechanical thermalanalyzer and prevent moisture loss during experiments, kernels were first wrapped with a thin layer of parafilm and then athin layer of aluminum foil. The wrapped kernels were then filed at both ends with fine sandpaper to produce 3 mm long ricecylinders with parallel ends. The dynamic mechanical properties of brown rice kernels were determined over a temperaturerange of -40C to 120C. During each DMTA test, the onset temperature of glass transition was measured as the Tg of a brownrice kernel, since moisture diffusion and other physical properties begin to change drastically above the onset temperature.No dramatic changes in both the storage modulus (E. ) and the loss modulus (E. ) of brown rice kernels were found aroundTg, indicating that relaxation of the amorphous phase of the rice kernel was quite limited. However, E. / E. (tan.) showeda much better transition for brown rice kernels, and thus the E. / E. vs. temperature curves were used to determine Tg valuesof rice kernels. It was found that the Tg values of rice kernels decreased linearly with increases in moisture content (MC) withinthe tested range. The Tg of rice kernels was not affected by variety.

A Comparison of Methods Used to Estimate River Rock Surface Areas

ABSTRACT Five methods for estimating the surface areas of river rocks were compared. True surface area was assumed to be estimated most accurately by wrapping the rock in a single layer of aluminum foil. Foil weight and tracing methods provided the closest estimates of true area. A volume displacement method was a poor estimator of area. A caliper method always underestimated true area, although the caliper method was fastest and could be completed in situ. Predictive relationships were established between true area and caliper method estimates for rocks from two rivers with distinctly different rocky substrates.

Delamination of Polyethylene and Aluminum Foil Layers of Laminated Packaging Material by Acetic Acid

ABSTRACTAcetic acid solutions (0.5, 1.0 and 3.0%) were packed in polyethylene aluminum foil laminated material and adhesion between the layers was measured during 28‐days storage at room temperature (∼23°C).Peel tests showed that in 3% acetic acid adhesion between layers was almost totally lacking after 4 days. After another 3 days the adhesion started to recover, and after 14 days it had returned to 50% of the initial value. Attenuated total reflection (ATR) tests after separation of the layers demonstrated that a salt layer was formed at the PE‐AI interface, Electron scanning for chemical analysis tests showed the presence of a thick oxidized layer on the aluminum foil and a trace of aluminum on the PE film.

A Versatile New Tactic for Fruit Tree Micrografting

Micrografting is au effective technique for elimination of viruses, early diagnosis of grafting incompatibilities, rejuvenation of mature tissue, and bypassing the juvenile phase in fruit trees. Current micrografting procedures are difficult, impractical, expensive, and generally result in an inefficient rate of successful graft production. To alleviate some of these limitations, a unique apparatus was designed to splice the in vitro-derived scion and rootstock together during the micrografting process. The dual-layer device was constructed with an outer layer of aluminum foil, with flexibility to facilitate manipulation during the grafting of micro-scale plants. A delicate, absorbent inner layer of paper toweling cushions the plant tissue. It also may be treated with hormones and other compounds. After healing, it is easy to remove the grafting apparatus from the grafted plant without damaging the tissues. This apparatus may be used to unite a scion and a rootstock with different stem diameters. Shoot-tip cultures of `McIntosh' and M.7 apple and `North Star' sour cherry, and in vitro seedlings of lemon, orange, and grapefruit were used as a source of in vitro scions and rootstocks. Successful graft unions were developed, and the grafted plants were transplanted into the greenhouse environment.

Aroma Sorption Evaluation of Aseptic Packaging

ABSTRACTA headspace method was developed for evaluating aroma sorption by polymeric packaging materials. Partition coefficients for ethyl acetate, n‐hexanal, d‐limonene and α‐terpineol at vapor activities of 0.2 were measured between air and the materials at 25°C and 40°C. Four different flexible aseptic packaging materials with barrier layers of aluminum foil, polyvinylidene chloride (SARAN), metallized polyester (MPET) and ethylene vinyl alcohol (EVOH) were evaluated. Temperature and aroma type had significant effects on partition coefficients. No significant interactions between aromas were observed in partition coefficients. The inner polyolefin sealing layer determined the aroma sorption behavior.

Effect of Light on the Pupariation of Liriomyza trifolii (Diptera: Agromyzidae)

In preliminary tests, emergent third-instar larvae (larvae after exiting from the leafmine) of Liriomyza trifolii (Burgess) subjected to a period of darkness were observed to pupate before those maintained under continuous lighting. Oatman (1959) reported this behavior for a similar species, L. pictella (Thomson). The experiment described here documents this behavior for L. trifolii. The mature L. trifolii third-instar larva exits the leafmine in the morning and drops to the ground to pupate (Leibee, 1984). This behavior facilitated the collection of mature third-instar larvae for use in this experiment. Infested carrot foliage was placed onto 0.64-cm (hole size) wire cloth over paraffin-coated cafeteria trays from 5 A.M. (the beginning of the photoperiod) to 9 A.M. to collect the larvae as they dropped from the foliage. The collection procedure was conducted in a fully lighted room maintained at 25?C. The cafeteria tray containing the larvae was removed from underneath the foliage at the end of the collection period. Twenty third-instar larvae were transferred with a camel's-hair brush to each of six plastic pill cups with caps. At 10 A.M., three of these cups were individually wrapped with two layers of aluminum foil to subject the larvae to complete darkness and placed along with the uncovered cups into a fully lighted growth chamber maintained at 25?C. Only the larval stage was present in the cups when placed into the growth chamber. The three uncovered cups were inspected at 15-min interals for the presence of puparia. After one h (11 A.M.), the three covered cups were unwrapped and included in the inspections for pupariation. The cumulative number of larvae that had pupariated was recorded after each 15-min interval. The results are presented in Table 1 as percent cumulative pupariation. The continuously lighted larvae pupariated at a relatively steady rate throughout the experiment once pupariation began. When the covered cups were unwrapped at the end of the 1-h dark period, it was found that significantly (P 0. 1) in percent cumulative pupariation between treatments. Pupariation was complete in both treatments after 225 min, indicating that pupariation could be delayed for only a limited amount of time regardless of lighting conditions. All the larvae subjected to darkness did not pupariate, indicating a difference in responsiveness to the absence of light. Since the larvae could have been from one to five hrs old at the beginning of the dark period, this difference in responsiveness might have been due to age with the younger larvae not having acquired the ability to pupariate during the dark period. The reduced amount of pupariation in the dark-treated larvae during the 30 minutes following the dark period was probably due to the large number of larvae pupariating earlier and leaving mostly larvae that were unable to pupariate. In conclusion, this study shows that pupariation of the emergent larva of L. trzfolii can be delayed for a limited time by continuous lighting. This behavior, in addition to

Laboratory Screening of Granular Soil Insecticides for Control of Sugarcane Beetle in Field Corn, 1982

Abstract Seven granular soil insecticides labeled for control of corn rootworm were tested for effectiveness against the sugarcane beetle. Treatments consisted of the amounts of each material that would be applied to 6 in of row at the labeled rate and at 2.0 times the labeled rate for corn rootworm control. All treatments were replicated 4 times. Treatments were applied by hand to soil in 6-in plastic pots in a manner that approximated 7-in band applications in the field. Insecticides were sprinkled onto the soil surface and covered with 1/4 in of soil and watered. Pots were again watered 6 days post treatment. Ten sugarcane beetles were introduced into each pot 9 days after treatment. Beetles were observed until all had burrowed into the soil. The pots were then covered with cardboard lids fitted with 1/8 in hardware cloth screening. Lids were secured on the pots by placing a length of 2 x 4 lumber on top of and across the lined up pots. The bottom of the pots were covered with 4 layers of aluminum foil to prevent beetles from escaping through drain holes. Pots were emptied, the soil sifted and the number of living and dead beetles counted 6 days after beetle introduction. Sugarcane beetles used in the experiments were collected at blacklight traps and held in the laboratory for 10-15 days prior to use in the experiment. The soil used in the experiments was a silt-sand, recent alluvial soil, obtained from the immediate bank of the Mississippi River.

Laboratory Evaluation of Granular Soil Insecticides for Control of Sugarcane Beetle in Field Corn, 1982

Abstract Six granular soil insecticides labeled for control of corn rootworm were tested for effectiveness against the sugarcane beetle at 12, 24, and 36 h post treatment. Treatments consisted of the amounts of each material that would be applied to 6-in row at the 1.0 lb/acre rate as registered for corn rootworm control. All treatments were replicated 4 times. Treatments were applied by hand to soil in 6-in plastic pots in a manner that approximated 7-in band applications in the field. Insecticides were sprinkled onto the soil and watered. Ten sugarcane beetles were introduced into each pot 8 h after treatment. Beetles were observed until all had burrowed into the soil. The pots were then covered with cardboard lids fitted with 1/8 in hardware cloth screening. Lids were secured on the pots by placing a length of 2 x 4 lumber on top of and across the lined up pots. The bottom of the pots were covered with 4 layers of aluminum foil to prevent beetles from escaping through drain holes. Pots were emptied, the soil sifted and the number of living and dead beetles counted at 3-12 h intervals after beetle introduction. Sugarcane beetles used in the experiments were collected at blacklight traps and held in laboratory for 10-15 days prior to use in the experiment. The soil used in the experiments was a silt-sand, recent alluvial soil, obtained from the immediate bank of the Mississippi River.