Effect Of Sample Preparation Methods Research Articles

Effects of Sample Preparation Methods on Permeability and Microstructure of Remolded Loess

To explore the influence of sample preparation methods on the permeability and microstructure of remolded loess, remolded loess collected from Heifangtai was taken as the research object. A total of 40 sets of falling-head permeability tests were conducted using two commonly used sample preparation methods, and five different dry density and four initial water content conditions. Additionally, the electrical conductivity of the leachate and the microscopic structure of the samples were analyzed. The results demonstrate that compared to the transfer wetting method, the homogeneity of samples prepared using the pre-wetting method is inferior. This difference is particularly evident when the initial water content is high. Due to the long duration of the permeability test, the pore structure is prone to change, resulting in relatively higher permeability coefficients. Moreover, the total dissolved solids (TDS) of the leachate exhibit a significant decrease with increasing seepage time, indicating the loss of soluble salts. Microscopic structural analysis reveals that samples prepared using the pre-wetting method exhibit a greater number of large pores and aggregates, which are intrinsic factors contributing to the observed differences in permeability between the two sample preparation methods. Furthermore, it should be noted that the impact of the sample preparation method on the permeability of remolded loess is more significant when the dry density is relatively low (specifically, less than 1.45 g/cm3). Conversely, when the dry density is higher, the influence becomes less pronounced.

Effects of sample preparation methods on measured characteristics of marine and fluvial sediment

Dredged sediment is complex material composed of mineral phases, organics phases, and liquid phases. For the characterization of sediment in the laboratory, the material should be dried before applying some tests, such as the determination of organic matter content, X-ray diffraction (XRD) analysis, X-ray fluorescence (XRF) analysis, specific surface area, specific gravity, and many other tests. To do such tests, in test standards, no specific drying method is recommended. This paper evaluates the effects of drying methods on the measured characteristics of dredged sediment. The drying methods investigated in the current study are oven-drying, freeze-drying, and air drying. From the results obtained, it seems that the drying method affects the results of the test done on the sediment. Among the drying methods, freeze-drying has less effect on sediment properties when the results are compared to a few properties measured on undried material. However, from the point of view of materials classification in road construction, no effects of drying methods are recorded.

Constitutive modelling of fabric effect on sand liquefaction

Sand liquefaction under static and dynamic loading can cause failure of embankments, slopes, bridges and other important infrastructure. Sand liquefaction in the seabed can also cause submarine landslides and tsunamis. Fabric anisotropy related to the internal soil structure such as particle orientation, force network and void space is found to have profound influence on sand liquefaction. A constitutive model accounting for the effect of anisotropy on sand liquefaction is proposed. Evolution of fabric anisotropy during loading is considered according to the anisotropic critical state theory for sand. The model has been validated by extensive test results on Toyoura sand with different initial densities and stress states. The effect of sample preparation method on sand liquefaction is qualitatively analysed. The model has been used to investigate the response of a sand ground under earthquake loading. It is shown that sand with horizontal bedding plane has the highest resistance to liquefaction when the sand deposit is anisotropic, which is consistent with the centrifuge test results. The initial degree of fabric anisotropy has a more significant influence on the liquefaction resistance. Sand with more anisotropic fabric that can be caused by previous loading history or compaction methods has lower liquefaction resistance.

Validation of sample preparation methods for small microplastics (≤10 µm) in wastewater effluents

The interest to monitor microplastics in various environmental matrices has grown substantially in recent years. However, monitoring microplastics remains a challenge due to interactions with complex environmental matrices, especially those rich in natural organic matter (NOM) like wastewater effluents. Therefore, sample preparation methods are needed to remove NOM and ensure minimal interference during analysis. So far, there have been only a few attempts to standardize and validate the effects of sample preparation methods on microplastics. However, no efforts exist that validated the impacts of sample preparation methods on small microplastic particles (≤10 µm). Those smaller particles might be more susceptible to adverse effects after chemical digestion as a result of the increased surface area to mass ratio, compared to their larger counterparts. In this study, pellets from six polymers were successfully tagged with a fluorescent dye and subsequently fractured using ultrasound treatment to produce small particles of tagged microplastic. The generated microplastics (≤10 µm) were then subjected to two sample preparation methods that were previously validated for wastewater effluents, namely Fenton and hydrogen peroxide oxidation. The effects on microplastics were assessed using size distribution changes, which were measured via fluorescence microscopy. Results revealed some large changes in the size distribution of microplastics (≤10 µm) after applying Fenton and hydrogen peroxide. However, these changes were largely reduced when excluding particles < 1 µm. The results indicated that, for the most part, both sample preparation methods can be used for small microplastic particles (1–10 µm), whereas hydrogen peroxide is more suitable if nanoplastics (<1µm) are to be investigated.

Small-strain shear modulus of calcareous sand under anisotropic consolidation

In this study, the small-strain shear modulus of a calcareous sand was investigated by conducting bender element tests on both horizontal and vertical planes. The effects of sample preparation method, stress path and stress history on the developing of void ratio, the parameters in the modified Hardin Equation, and the stiffness anisotropy were examined. The test results show that the moist tamping samples have the least void ratio variation among the five samples. The void ratio recovery in effective horizontal stress [Formula: see text] = 100 kPa tests is higher than that in the effective vertical stress [Formula: see text] = 100 kPa tests. The samples prepared in the dry state have lower stiffness than those prepared in the moisture state, which is not influenced by the anisotropic stress state. The stiffness anisotropy induced by the sample preparation method is significant under anisotropic consolidation. In [Formula: see text] = 100 kPa tests, the stiffness ratios at the end of the unloading stage are lower than the initial values at the loading stage, which is not found in the [Formula: see text] = 100 kPa tests, meaning that the stress history and stress path could affect the stiffness anisotropy and eliminate the impact of fabric anisotropy.

Effect of sample preparation method on mechanical behaviour of fibre-reinforced sand

It is well known that the mechanical behaviour of pure sand is dependent on the internal soil structure, which can be affected by sample preparation methods. For fibre-reinforced sand (FRS), the sample preparation methods influence not only the internal structure of sand skeleton but also the distribution of fibre orientation and sand-fibre interaction. The effect of sample preparation methods on the mechanical behaviour of FRS has been investigated using comprehensive drained triaxial compression tests. The soil samples have been prepared by moist tamping (MT) and moist vibration (MV). There is a small difference in the stress-strain relationship of pure sand with different sample preparation methods. But the response of FRS is dramatically different. Under the same initial conditions of void ratio, confining pressure and fibre content, FRS prepared using the MV method shows 30–50% higher peak deviator stress and much less dilative response. A newly developed constitutive model is used to simulate the stress-strain relationship of FRS prepared using different methods.

Effect of Sample Preparation Methods on the Prediction Performances of Near Infrared Reflectance Spectroscopy for Quality Traits of Fresh Yam (Dioscorea spp.)

High throughput techniques for phenotyping quality traits in root and tuber crops are useful in breeding programs where thousands of genotypes are screened at the early stages. This study assessed the effects of sample preparation on the prediction accuracies of dry matter, protein, and starch content in fresh yam using Near-Infrared Reflectance Spectroscopy (NIRS). Fresh tubers of Dioscorearotundata (D. rotundata) and Dioscoreaalata (D. alata) were prepared using different sampling techniques—blending, chopping, and grating. Spectra of each sample and reference data were used to develop calibration models using Modified Partial Least Square (MPLS). The performance of the model developed from the blended yam samples was tested using a new set of yam samples (N = 50) by comparing their wet laboratory results with the predicted values from NIRS. Blended samples had the highest coefficient of prediction (R2pre) for dry matter (0.95) and starch (0.83), though very low for protein (0.26), while grated samples had the lowest R2pre of 0.87 for dry matter and 0.50 for starch. Results showed that blended samples gave a better prediction compared with other methods. The feasibility of NIRS for the prediction of dry matter and starch content in fresh yam was highlighted.

A thermogravimetric study of HDPE conversion under a reductive atmosphere

The plastic waste has suffered a dramatic increase and has become one of the biggest environmental problems nowadays. The chemical transformation of plastics by catalytic cracking under hydrogen atmosphere (hydrocracking) is one of the viable solutions to this problem since it can convert plastic residues into petrochemicals and fuels. In this work a thermogravimetric study of high-density polyethylene (HDPE) conversion under hydrogen atmosphere and in the presence of catalysts with different textural and chemical features is presented. The effect of distinct micro (H-ZSM-5, H-FER and H-MOR) and mesoporous (SBA-15 and MCM-41) catalysts is studied, both in terms of energy requirements and products distribution. Moreover, the effects of sample preparation method, catalyst amount, Si/Al ratio and incorporation of a metallic function (Ni and Pt) are also analyzed. The results show that when MCM-41 and SBA-15 mesoporous silicas are added to HDPE no significant changes are observed in terms of the degradation profile. On the contrary, the use of microporous materials decreases significantly the onset of HDPE degradation temperature. The accessibility and acidic content of the materials proved to be the most important factors influencing the HDPE degradation profiles. Moreover, the introduction of a metal function results in a further shift to lower degradation temperatures and favors the liquid products distribution, promoting the formation of gasoline and diesel.

The Effect of in Vitro Sample Preparation Methods on Bond Strength of Mineral Trioxide Aggregate to Root Dentin.

The aim of this study was to compare the effect of sample preparation methods on push-out bond strength of mineral trioxide aggregate (MTA). Twenty-four extracted human mandibular premolars with single root canal were selected for this in vitro study. After instrumentation, irrigation and drying of root canals, they were randomly divided into two experimental groups (n=12). Group 1: After removing the 3 mm of root ends, 2 mm thick sections were established from the remaining roots. MTA was mixed following the manufacturers' recommendations and root sections were filled. Group 2: The whole root canal was used for filling and packing of MTA and like group 1, after removing the 3 mm of root ends, root sections were provided. Push-out bond strength was measured and analyzed by the independent t-test. Level of statistical significance was set at 0.05. The highest mean push-out bond strength was in apical section of group 2 (4.86±1.31) and the lowest value was in coronal section of group 2 (3.05±1.15). The results of the independent t-test showed a significant difference between two groups only in the apical section (P=0.02). Based on the results of this in vitro study, the highest mean push-out bond strength was in apical section of group 2. It seems that using the whole root canal for MTA application is better for MTA in vitro analysis of bond strength to root dentin because it is more similar to the clinical conditions.

Effects of Sample Preparation Methods for the Isolation of Foodborne Pathogens from Sprout Seeds

Effects of Sample Preparation Methods for the Isolation of Foodborne Pathogens from Sprout Seeds

Repeatability and reproducibility of micro-surfacing mixture design tests and effect of aggregates surface areas on test results

The first part of this study evaluates the repeatability of the International Slurry Surfacing Association (ISSA) mixture design tests. Consistency of test results between two laboratories (MTQ and LCMB) was evaluated. Aggregate gradation and sample preparation method were varied, and the responses for various ISSA mix design test for micro-surfacing were examined. The repeatability of four ISSA mix design tests for micro-surfacing was computed. To do this, the micro-surfacing mixtures were prepared by four technicians in two separate laboratories in Quebec. The modified cohesion test, the wet track abrasion test, the loaded wheel test, and the resistance to compaction test were evaluated in this study. The effect of sample preparation method using aggregate splitting and sieve analysis on consistency of mixture design test results was also evaluated. It was observed that employing sieve analysis method for micro-surfacing mixture preparation yields better consistency in test responses. For the second part of this study, the role of aggregate gradation, and their total surface area on cohesion, resistance to abrasion, and resistance to permanent deformation of micro-surfacing mixtures was studied. Two different type III applications of micro-surfacing mixtures, which are used as rut-fill materials in high traffic area, were selected to determine the effects of aggregate total surface area on micro-surfacing mix design test responses. It was found that the micro-surfacing mixtures prepared using aggregate gradation with more fine aggregates have higher resistance to rutting, bleeding, abrasion and moisture susceptibility.

Repeatability and reproducibility of micro-surfacing mixture design tests and effect of total aggregates surface areas on the test results

The first part of this study evaluates the repeatability of the International Slurry Surfacing Association (ISSA) mixture design tests. Consistency of test results between two laboratories (MTQ and LCMB) was evaluated. Aggregate gradation and sample preparation method were varied, and the responses for various ISSA mix design test for micro-surfacing were examined. The repeatability of four ISSA mix design tests for micro-surfacing was computed. To do this, the micro-surfacing mixtures were prepared by four technicians in two separate laboratories in Quebec. The modified cohesion test, the wet track abrasion test, the loaded wheel test, and the resistance to compaction test were evaluated in this study. The effect of sample preparation method using aggregate splitting and sieve analysis on consistency of mixture design test results was also evaluated. It was observed that employing sieve analysis method for micro-surfacing mixture preparation yields better consistency in test responses. For the second part of this study, the role of aggregate gradation, and their total surface area on cohesion, resistance to abrasion, and resistance to permanent deformation of micro-surfacing mixtures was studied. Two different type III applications of micro-surfacing mixtures, which are used as rut-fill materials in high traffic area, were selected to determine the effects of aggregate total surface area on micro-surfacing mix design test responses. It was found that the micro-surfacing mixtures prepared using aggregate gradation with more fine aggregates have higher resistance to rutting, bleeding, abrasion and moisture susceptibility.

Effects of Sample Preparation Methods on Tensile Strength of Red Clay

Effects of two sample preparation methods on tensile strength of red clay are studied. The first method adopts standard layered-bumping to make sample whose layer interfaces are vertical to tensile force. The second method uses compaction apparatus to prepare big sample and the big sample is cut to prepare triaxial sample whose layer interface is parallel to tensile force. Test results indicate that the layer interfaces of soil sample have large influence on the single axle tension test, because the results of the sample prepared by 1st method have large dispersion and low strength, while the results of the sample prepared by 2nd method are just the opposite.Moreover,the layer interfaces of soil sample have little influence on the unconfined compressive strength test, and the results of the tensile test and unconfined compressive strength test of the samples prepared by 2nd method meet with the Griffith Criterion, so the samples of uniaxial tension test should be prepared by 2nd method.

Effect of Sample-Preparation Method on Critical-State Behavior of Sands

It is well-known that specimen-preparation method and the resulting sand fabric significantly affect sand behavior. In many cases, the fabric and behavior of reconstituted sand samples do not represent those of in-situ deposits. Therefore, understanding the influence of specimen preparation and sand fabric on its behavior, particularly at the critical state, is important for relating the behavior of laboratory reconstituted specimens to in-situ soil response. In this study, the effect of sand fabric and specimen-preparation method on the shearing behavior of three sands is studied using ring-shear tests. Ring-shear tests are used to reach large shear displacements and determine critical states, particularly for dense sand specimens. Moist tamping and air pluviation are used to prepare the specimens. The results indicate that the shearing behavior of sand in ring-shear tests is not only affected by the specimen-preparation method (i.e., sand fabric), but also by particle damage and compressibility. However, these mechanisms do not affect the critical states at which particle rearrangement and damage are complete and the initial sand fabric is completely erased.

Thermodynamic analysis of lipoic acid crystallized with additives

Differential scanning calorimetry (DSC) was used as a screening technique to study the interaction between lipoic acid and amino acids. The samples containing lipoic acid and amino acids were prepared by two different methods (milling method and cooling crystallization method). Firstly, cooling method was used to prepare the sample with amino acids as additives. DSC results indicated that only phenylalanine has some interaction with lipoic acid. Further, in order to study the interaction between lipoic acid and phenylalanine, another method (milling method) was used to prepare the sample containing phenylalanine, and the effect of sample preparation methods was studied through IR analysis and the X-ray powder diffraction. On the basis of above researches, the possible interaction mechanisms between lipoic acid and phenylalanine were proposed.

Effect of sample preparation methods on the d,l-enantiomer ratio of extracted selenomethionine

Effects of the two most widespread sample preparation techniques on the D,L-enantiomer ratio of extracted selenomethionine were monitored through the analysis of the certified reference material selenium-enriched yeast and the isolated protein fraction of high selenium monkeypot nut. The extracted selenomethionine (SeMet) fractions were orthogonally cleaned up with anion exchange chromatography before carrying out the enantiomer-specific detection to increase the robustness and the efficiency of the subsequent o-phthal-aldehyde and n-isobutyril-cysteine-based derivatisation process and reversed phase-high-performance liquid chromatography-inductively coupled plasma mass spectroscopy (ICP-MS) detection. The two techniques, namely methanesulphonic acid (MSA) based digestion and proteolytic digestion with protease XIV, resulted in significantly different ratio of D,L-selenomethionine with the final results of 2.2-2.7% and 0.5-0.6% of D-SeMet, respectively. The study revealed significant differences in the ICP-MS-related sensitivity of the derivatised selenomethionine enantiomers, which calls attention to the quantification of this selenoamino acid after MSA hydrolysis.

Annealing effect upon chain orientation, crystalline morphology, and polarizability of ultra-thin P(VDF-TrFE) film for nonvolatile polymer memory device

The ferroelectric behavior of spin-cast ultra-thin P(VDF-TrFE) (72-28) film is highly influenced by sample preparation methods including thermal annealing. The effect of sample preparation methods on the surface morphology, chain and dipole orientation, ferroelectric properties, and nonvolatile memory characteristics were studied using FTIR-grazing incident reflection absorption spectroscopy (GIRAS), grazing incident wide angle X-ray diffraction (GIWAXD), atomic force microscope (AFM), dynamic contact electrostatic force microscope (DC-EFM), and polarization-electric field ( P- E) hysteresis measurements to find the feasibility of applying the ultra-thin P(VDF-TrFE) film to scanning probe microscopy (SPM)-based storage device or low-cost nonvolatile ferroelectric polymer random access memory (NvFePoRAM) device. From the collective analysis of GIRAS, GIWAXD, and AFM data, annealing the as-cast sample at temperature (ca. 120 °C) above Curie transition, but below its melting transition temperature was found to be the most suitable condition to fabricate the NvFePoRAM and/or SPM-based storage device with a memory density of about 30 GB/in 2. DC-EFM technique was successfully used to characterize the nonvolatile memory properties by ‘writing and erasing’ the data bit through applying a dc bias voltage much larger than coercive voltage with different polarities and then reading the data bit by applying a high frequency ac voltage of only 2 V to the ‘written or erased’ area.

Rapid quantification of conjugated and unconjugated bile acids and C27 precursors in dried blood spots and small volumes of serum

The aim of the study was to develop a method for fast and reliable diagnosis of peroxisomal diseases and to facilitate differential diagnosis of cholestatic hepatopathy. For the quantification of bile acids and their conjugates as well as C(27) precursors di- and trihydroxycholestanoic acid (DHCA, THCA), in small pediatric blood samples we combined HPLC separation on a reverse-phase C18 column with ESI-MS/MS analysis in the negative ion mode. Analysis was done with good precision (CV 3,7%-11.1%) and sufficient sensitivity (LOQ: 11-91 nmol/L) without derivatization. Complete analysis of 17 free and conjugated bile acids from dried blood spots and 10 microL serum samples, respectively, was performed within 12 min. Measurement of conjugated primary bile acids plus DHCA and THCA as well as ursodeoxycholic acid was done in 4.5 min. In blood spots of healthy newborns, conjugated primary bile acids were found in the range of 0.01 to 2.01 micromol/L. Concentrations of C(27) precursors were below the detection limit in normal controls. DHCA and THCA were specifically elevated in cases of peroxysomal defects and one Zellweger patient.

Effect of sample preparation method on quantification of polymorphs using PXRD

The purpose of this study was to improve the sensitivity and accuracy of quantitative analysis of polymorphic mixtures. Various techniques such as hand grinding and mixing (in mortar and pestle), air jet milling and ball milling for micronization of particle and mixing were used to prepare binary mixtures. Using these techniques, mixtures of form I and form II of clopidogrel bisulphate were prepared in various proportions from 0–5% w/w of form I in form II and subjected to x-ray powder diffraction analysis. In order to obtain good resolution in minimum time, step time and step size were varied to optimize scan rate. Among the six combinations, step size of 0.05° with step time of 5 s demonstrated identification of maximum characteristic peaks of form I in form II. Data obtained from samples prepared using both grinding and mixing in ball mill showed good analytical sensitivity and accuracy compared to other methods. Powder x-ray diffraction method was reproducible, precise with LOD of 0.29% and LOQ of 0.91%. Validation results showed excellent correlation between actual and predicted concentration with R2 > 0.9999.

Effect of sample-preparation methods on the quantification of selected flavonoids in plant materials by high performance liquid chromatography

Summary. Extraction yield of flavonoids from plant material Sambucus nigra L. inflorescence and Polygonum aviculare herb was determined by use of various methods of liquid–solid extraction – Soxhlet extraction, ultrasonification (USAE), microwaveassisted extraction (MASE), and accelerated solvent extraction (ASE). Methanol was used as extractant. Crude extracts were evaporated to dryness and prepared to achieve fractionation of flavonoids by LLE or SPE. Samples containing the flavonoid fraction were analysed by RP-HPLC. For quantitative purposes the external standard method with a calibration plot for every standard was used. It was found that yield depends first of all on the plant material from which flavonoid fraction was extracted. For Sambucus nigra L. inflorescence the most effective method was exhaustive extraction in a Soxhlet apparatus. For Polygonum aviculare the most effective method was ASE. The best purification method was SPE on C18 adsorbent, which resulted in the highest recoveries and repeatabilities.