Reliability Of Test Results Research Articles

Comparison of one-step with two-step production of Bacillus atrophaeus spores for use as bioindicators.

The production method of spores significantly influences the resistance of spores used as bioindicators (BI) in the validation of sterilization of packaging material surfaces in aseptic food manufacturing. Therefore, the standardization of the spore production method represents an important and desirable goal in industrial BI production to ensure reliable validation test results. Previously, we recommended a two-step production approach for submerged spore production, in which the cultivation phase to obtain high cell mass was separate from the sporulation phase. In this work, a one-step manufacturing process was investigated to reduce production complexity and facilitate standardization of spore production. It was found that one-step BI production is technically possible but at the expense of spore yield. The two-step manufacturing process can realize almost 10-fold higher spore yields.

Design for Weapon Live Test Decision Support System Using Digital Twin Architecture

The purpose of the weapon live test during the phase of development is to provide essential information to decision makers that verify and validate the performance capabilities of weapons. Due to varying allocation and high variance of test resources with an increase in the weapon system’s capability, the test environment can get highly complex, which can lead to a decrease in the reliability of test results. This issue can be addressed by applying a decision support system that provides various timely information collected by resources during the test process. The decision support system can be designed by applying the concept of digital twins, that are defined as digital replicas of components, systems and processes. This paper describes a design methodology of the decision support system that consists of digital models and service functions using digital twin architecture. A case study illustrates the feasibility of the proposed methodology in supporting the weapon live test process.

Stability of Selected Biochemical Analytes in Serum Stored at Room Temperature for 24 Hours at Kericho County Referral Hospital, Kenya

Accurate and reliable medical laboratory test results are essential for correct patient diagnosis and management. This is however influenced by many preanalytical, analytical, and post-analytical factors. A general problem faced by most clinical laboratories is the inability to timely process all blood samples received due to overwhelming workload, reagents stock-outs, and equipment breakdown, necessitating storage which predisposes analytes to deterioration. To ensure accurate results from stored samples, the determination of the stability of the analytes under various environmental conditions and storage periods is important in informing acceptable sample handling and storage. This study was designed to experimentally observe changes and evaluate the stability of eleven biochemical analytes in serum samples from 20 randomly sampled healthy volunteers stored at room temperature over 24 hours at Kericho County Referral Hospital laboratory. 10mls of venous blood was drawn from each volunteer, serum was separated and five aliquot sets were prepared. Analysis was done on a set immediately, at 2, 4, 8, and 24 hours, to determine the concentration of the selected analytes on Human Star 100 chemistry analyser. Student pair T-test and Wilcoxon rank were used to analyse the data. Chloride, Creatinine, Glucose, Potassium, Sodium, Urea, Alkaline Phosphatase, Alanine Amino Transferase and Aspartate Amino Transferase registered stability up to 24 hours, with mean percentage differences less the respective calculated reference change value of 4.54, 35.97, 13.14, 10.89, 2.16, 32.15, 16.48, 42.25 and 42.52. Direct and total bilirubin showed stability only up to 2 and 4 hours, respectively, with mean percentage differences of -2.6 and 1.07 against respective calculated reference change values of 1.14 and 0.675 in the subsequent analysis. This study recommends immediate analysis of serum for total and direct bilirubin, while electrolytes, enzymatic analytes and other metabolic waste and substrates can be analysed within 24 hours without extra storage precautions. If testing is delayed, then effective storage including a dark room, refrigeration, or freezing, should be applied to maintain analytes stability for reliable results.

Point of care SARS-CoV-2 nucleic acid testing in schools improves school attendance.

Background: National lockdowns have led to significant interruption to children's education globally. In the Autumn term in 2020, school absence in England and Wales was almost five times higher than the same period in 2019. Transmission of SARS-CoV-2 in schools and ongoing interruption to education remains a concern. However, evaluation of rapid point of care (POC) polymerase chain reaction (PCR) testing in British schools has not been undertaken. Methods: This is a survey of secondary schools in England that implemented PCR-based rapid POC testing. The study aims to measure the prevalence of SARS-CoV-2 infection in schools, to assess the impact of this testing on school attendance and closures, and to describe schools experiences with testing. All schools utilised the SAMBA II SARS-CoV-2 testing platform. Results: 12 fee-paying secondary schools in England were included. Between September 1 st 2020 and December 16 th 2020, 697 on site rapid POC PCR tests were performed and 6.7% of these were positive for SARS-CoV-2 infection. There were five outbreaks in three schools during this time which were contained. Seven groups of close contacts within the school known as bubbles had to quarantine but there were no school closures. 84% of those tested were absent from school for less than one day whilst awaiting their test result. This potentially saved between 1047 and 1570 days off school in those testing negative compared to the NHS PCR laboratory test. Schools reported a positive impact of having a rapid testing platform as it allowed them to function as fully as possible during this pandemic. Conclusions: Rapid POC PCR testing platforms should be widely available and utilised in school settings. Reliable positive tests will prevent outbreaks and uncontrolled spread of infection within school settings.Reliable negative test results will reassure students, parents and staff and preventdisruption to education.

Solving the Moment Amplification Factor of a Lateral Jet by the Unsteady Motion Experimental Method

In this paper, unsteady motion tests of a lateral jet adjusting an air vehicle’s attitude are carried out. Curves of pitch moment amplification factors (KM) for a lateral jet versus angle of attack (α) are obtained using a wind tunnel free-flight test technique with a jet and data processing method. This new method overcomes the disadvantage of previous experiments that can study only one unsteady characteristic. The free-flight test technique in the proposed method ensures that the test model can be coupled in real-time with multiple parameters (unsteady flow caused by the jet, unsteady air vehicle aerodynamic force, and unsteady air vehicle motion). This approach simulates an actual air vehicle’s complete jet test process and ensures more authentic and reliable test results. In the new data processing method, continuous data curves are fitted to discrete data points, making it easier to convert the angular displacement versus time curve into the pitch moment versus α curve to obtain KM. The results show that when the pressure of the micro high-pressure gas cylinder is 2.0 MPa, KM is below 1, indicating that the lateral jet does not significantly promote the pitching moment. When the gas cylinder pressure is 4.0 MPa and the angle of attack is 5° < |α| < 16°, KM is greater than 1, and the lateral jet promotes the pitching moment. When 16° < |α| < 20°, KM is less than 1, and the lateral jet does not significantly contribute to the pitching moment. It was further found that KM decreases slowly with increasing α. When |α| > 30°, the influence of the jet on the pitching moment nearly disappears.

Point of care SARS-CoV-2 nucleic acid testing in schools improves school attendance

Background: National lockdowns have led to significant interruption to children’s education globally. In the Autumn term in 2020, school absence in England and Wales was almost five times higher than the same period in 2019. Transmission of SARS-CoV-2 in schools and ongoing interruption to education remains a concern. However, evaluation of rapid point of care (POC) polymerase chain reaction (PCR) testing in British schools has not been undertaken. Methods: This is a survey of secondary schools in England that implemented PCR-based rapid POC testing. The study aims to measure the prevalence of SARS-CoV-2 infection in schools, to assess the impact of this testing on school attendance and closures, and to describe schools experiences with testing. All schools utilised the SAMBA II SARS-CoV-2 testing platform. Results: 12 fee-paying secondary schools in England were included. Between September 1 st 2020 and December 16 th 2020, 697 on site rapid POC PCR tests were performed and 6.7% of these were positive for SARS-CoV-2 infection. There were five outbreaks in three schools during this time which were contained. Seven groups of close contacts within the school known as bubbles had to quarantine but there were no school closures. 84% of those tested were absent from school for less than one day whilst awaiting their test result. This potentially saved between 1047 and 1570 days off school in those testing negative compared to the NHS PCR laboratory test. Schools reported a positive impact of having a rapid testing platform as it allowed them to function as fully as possible during this pandemic. Conclusions: Rapid POC PCR testing platforms should be widely available and utilised in school settings. Reliable positive tests will prevent outbreaks and uncontrolled spread of infection within school settings. Reliable negative test results will reassure students, parents and staff and prevent disruption to education.

Impact of Preanalytical Factors on Calprotectin Concentration in Stool: A Multiassay Comparison.

Measuring calprotectin concentration in stool is increasingly important in monitoring disease activity and treatment response in inflammatory bowel disease. This study evaluates the impact of preanalytical storage conditions on reliability of calprotectin testing using 5 different calprotectin immunoassays. Aliquots of homogenized fresh fecal samples in untreated or extracted form were stored at room temperature or 4°C. Calprotectin concentration was measured day 0 to 4 and 8. Five different immunoassays and accompanying extraction buffers were used (CALiaGold, Phadia EliA, Bühlmann fCal turbo, ELISA Bühlmann, Inova Quanta Flash). Repeated measurements of change from baseline calprotectin levels over time were analyzed using a mixed model analysis. Calprotectin concentrations declined over time under all preanalytical conditions with all assays, except for extracted feces stored at 4°C. The rate of decline was greatest in untreated stool kept at room temperature, reaching significant difference from baseline already after 1 day (P < 0.001). In extracted feces kept at room temperature, significant difference from baseline was reached after 2 days, and in untreated feces at 4°C, after 4 days. However, the results differed significantly between assays. After 4 days of storage at room temperature, the mean calprotectin decline from baseline differed between 30% and 60%, dependent on the assay used. Fecal calprotectin concentration in stool samples declines over time, and the rate of decline is greater at higher temperatures. In extracted feces stored at 4°C, calprotectin is most stable. It is assay-dependent how long extracted feces stored at 4°C give reliable test results.

Lifting the Veil: Characteristics, Clinical Significance, and Application of β-2-Microglobulin as Biomarkers and Its Detection with Biosensors.

Because β-2-microglobulin (β2M) is a surface protein that is present on most nucleated cells, it plays a key role in the human immune system and the kidney glomeruli to regulate homeostasis. The primary clinical significance of β2M is in dialysis-related amyloidosis, a complication of end-stage renal disease caused by a gradual accumulation of β2M in the blood. Therefore, the function of β2M in kidney-related diseases has been extensively studied to evaluate its glomerular and tubular functions. Because increased β2M shedding due to rapid cell turnover may indicate other underlying medical conditions, the possibility to use β2M as a versatile biomarker rose in prominence across multiple disciplines for various applications. Therefore, this work has reviewed the recent use of β2M to detect various diseases and its progress as a biomarker. While the use of state-of-the-art β2M detection requires sophisticated tools, high maintenance, and labor cost, this work also has reported the use of biosensor to quantify β2M over the past decade. It is hoped that a portable and highly efficient β2M biosensor device will soon be incorporated in point-of-care testing to provide safe, rapid, and reliable test results.

An Optical Fiber Sensing Method for Measuring the Surface Flatness of an Object.

Sensing of data or object is a mature research domain where intelligent devices, may possibly be embedded with the artificial intelligence-based techniques, are placed in the closed vicinity of the object or phenomenon. This sensing activity becomes more complex if it is related to the measurements of an object which is required to be accurate and precise. In this paper, the reflection interference spectrum method is used to measure the flatness of the surface of the object. The thickness of the tested object is between 0.4 and 16 μm. The optical fiber sensor is moved on the surface of the object, and the reflection spectrum of each point on the surface of the object is analyzed. The thickness of each point, and through the movement of the stepping motor, the thickness of different points on the object is continuously measured, so as to obtain the surface topography of the object. This method has no destructive effect on the surface of the object, has no lateral test range limitation, and has a simple test system structure, High test accuracy, and reliable test results.

PB2325: APPLICATION AND COMPARISON OF TWO PHARMACOKINETIC DETECTION METHODS IN CHILDREN WITH HEMOPHILIA A—AN INSPECTION REPORT FROM SINGLE CENTER

Background: Personalized prophylaxies for moderate and severe hemophilia A and B are based on personal pharmacokenetics (PK), half-life(T1/2). While classical method for personal PK needs multiple blood collections, at least 5 points collections for children and 11points for adults, and expensive for testing and leads low compliance. Popular PK based on pupolar data can have a less blood collections but a rough data(range) is recommended for reference. One-chamber model may also have a less blood collection 2-3 collections for PK detection. Aims: Objective: To analyze and compare the half-life (T1/2) results of Factor VIII (FVIII) calculated by modified one-chamber model by “CAI’s” hemophilia pharmacokinetic calculation tool and WinNolin software (five-point sampling), non-av model, and to explore the reliability and clinical application value of “CAI’s” hemophilia pharmacokinetic calculation tool. Methods: A total of 30 patients with moderate and severe hemophilia A were treated with FVIII (50IU/Kg) after the 72-hour elution period. Peripheral blood samples were collected at five time points before and after FVIII injection (0h, 1h, 9h, 24h, 48h), and FVIII activity was detected by one-stage method. The T1/2 of FVIII was calculated by WinNolin software. Two of the three time points of FVIII activities (9h~24h, 9h~48h, 24h~48h) were used to calculate the FVIII T1/2 by “CAI’s” hemophilia A pharmacokinetic calculation tool, and the results were compared with those of WinNolin software, and the correlation analysis was conducted. Results: 1. 30 cases of T1/2 of FVIII calculated by WinNolin software was from 5.55 hs to 12.5 hs. 2. Compared with WinNolin software (five-point method, the results of T1/2 of FVIII caculated by “CAI’s” hemophilia A pharmacokinetic calculation tool, (the modified one-chamber model method) at 9h~24h, 9h~48h and 24h~48h showed that the detection periods with highist consistent T1/2 were 9h~48h, 24 out of 30, 80.0%, while 9h~24h 6 out of 30, 20.00%; 3. Correlation analysis shows that there is a good correlation between the T1/2 of the modified one-chamber model and the results of WinNolin’s calculation in all three time periods, but the correlation/consistency is the highest in the period of 9h~48h (see fig 1); 4. Analysis of the FVIII T1/2 results of 9h~24h, 9h~48h and 24h~48h we found that there were 8 out of 30 cases (26.67%) of T1/2 were basically stable at the same level, while 53.33% (16/30) of the children had significant changes at each time period. Image:Summary/Conclusion: 1. Compared with the T1/2 results by WinNolin’s method and modified ond-chambor modle (”CAI’s” tool), the most consistency of T1/2 of blood sampling was 9h~48h. However, for those T1/2 short than 7~8hs, the detection time should be adjusted (the later blood sample taking should be adjust to earlier); 2. Nearly 3/4 of the 30 cases, the T1/2 results fluctuated among three periods (9h~24h, 24h~48h, 9h~48h) in one case, suggesting a standardized test procedures such as specimen collection, sample transportation and detection ect needs to set up to ensure the stability and reliability of test results. 3. The classical pharmacokinetic test requires at least 5 points of blood sample collections, which is difficult to be popularized and applied in clinical practice. If a standardized and standardized testing process is established, the one-chamber model method is relatively simple and easy to be accepted and popularized by patients. Key words: hemophilia A, pharmacokinetics, children, one-chamber model, non-av-model

Assay validity of point-of-care platelet function tests in thrombocytopenic blood samples.

IntroductionPoint-of-care (POC) platelet function tests are faster and easier to perform than in-depth assessment by flow cytometry. At low platelet counts, however, POC tests are prone to assess platelet function incorrectly. Lower limits of platelet count required to obtain valid test results were defined and a testing method to facilitate comparability between different tests was established.Materials and methodsWe assessed platelet function in whole blood samples of healthy volunteers at decreasing platelet counts (> 100, 80-100, 50-80, 30-50 and < 30 x109/L) using two POC tests: impedance aggregometry and in-vitro bleeding time. Flow cytometry served as the gold standard. The number of platelets needed to reach 50% of the maximum function (ED50) and the lower reference limit (EDref) were calculated to define limits of test validity.ResultsThe minimal platelet count required for reliable test results was 100 x109/L for impedance aggregometry and in-vitro bleeding time but only 30 x109/L for flow cytometry. Comparison of ED50 and EDref showed significantly lower values for flow cytometry than either POC test (P value < 0.05) but no difference between POC tests nor between the used platelet agonists within a test method.ConclusionCalculating the ED50 and EDref provides an effective way to compare values from different platelet function assays. Flow cytometry enables correct platelet function testing as long as platelet count is > 30 x109/L whereas impedance aggregometry and in-vitro bleeding time are inconsistent unless platelet count is > 100 x109/L.

A retrospective cohort study of the effect of SARS-CoV-2 point of care rapid RT-PCR at the Emergency Department on targeted admission

BackgroundTo prevent nosocomial transmission of SARS-CoV-2, infection prevention control (IPC) measures are implemented for patients with symptoms compatible with COVID-19 until reliable test results are available. This delays admission to the most appropriate ward based on the medical condition. SARS-CoV-2 rapid antigen detection (RAD) tests and point-of-care (POC) rapid RT-PCR (VitaPCR) were introduced at emergency department (ED) at Skåne University Hospital, Sweden in late 2020, but the consequence on patient flow and targeted admission is unknown.MethodsPatients presenting at the emergency department of a referral hospital (N = 2940) between 13-Nov-2020 and 12-Jan-2021 were included. The study period was delimited into three periods by the introduction of RAD tests and the VitaPCR. Participant data was collected from hospital records, and outcome variables were Length-of-Stay (LoS), intrahospital transfers and targeted admission to COVID-19 ward.ResultsCompared to baseline (RT-PCR only), RAD tests reduced ED Length-of-Stay (LoS) for participants with positive tests. Negative VitaPCR results reduced mean hospital LoS by 1.5 (95% CI 0.3–2.7) days and admissions to COVID-19 wards from 34.5 (95% CI 28.9–40.5) to 14.7 (95% CI 11.1–19.1) per 100 admissions and reduced transfers between hospital wards in the first 5 days from 50.0 (95% CI 45.0–55.0) to 34.0 (95% CI 30.3–37.9) per 100 admissions.ConclusionRAD tests enabled prompt detection of SARS-CoV-2 infection which had pronounced effects on LoS at the ED. Negative VitaPCR enabled cessation of IPC measures and a negative test was associated with increased targeted admissions, reduced intrahospital transfers and shorter LoS at the hospital.

Standardization of Manual Method of Immunohistochemical Staining for Breast Cancer Biomarkers at Tertiary Cancer Care Center: An Audit

Immunohistochemistry (IHC) is a necessary ancillary technique in surgical pathology laboratories, particularly for oncology tissue specimens. Automation in the IHC technique has an advantage over manual methods in terms of quality, except for the cost of the equipment. Thus, the manual method of IHC staining is the preferred method of choice in countries with limited resources. However, standardization of all steps in the preanalytic phase is critical to obtain reliable immunohistochemistry test results. The current audit was conducted to describe the preanalytic factors affecting manual IHC methods. The most important preanalytic factors were fixative, the composition of dehydrate, pH, drying of sections, and heat-mediated antigen retrieval method (HMAR). The domestic pressure cooker method was found to be the best for HMAR.

Restoration of the Indicator Properties of Whole-cell Luminescent Biosensors

Whole-cell biosensors are widely used to produce medical diagnostic tests, but in the long term, they tend to lose their indicator properties. Consequently, it is crucial to find ways to restore these properties and prolong the shelf life of the tests. Here, we propose to use electromagnetic radiation with optimally selected parameters of frequency, power, and exposure time. The impact of radiation parameters on biosensor luminescence was studied as well as the effects of different types of radiation coming from laser sources (λ = 875nm), a LED source (λ = 850 ÷ 890nm), and microwave units (at frequencies 42.22, 53.53, 61.18 и 34 ÷ 38GHz). IR treatment resulted in dose-dependent suppression of biosensor luminescence. The luminescence level when exposed to microwave radiation depends on the radiation time and frequency. Also, it has been found that optimal selection of the main radiation parameters enables to restore indicator properties partially lost by biosensors during storage. We explain the mechanism responsible for the sensitizing effect of radiation, which implies the polarization of solvent dipoles and changes in mobility of acceptor molecules. This, in turn, leads to a shift in the chemical equilibrium states and triggers a cascade of biochemical reactions that lead to restoration of the lost indicator properties of biosensors. The study of antagonistic activity has revealed that restored biosensors provide reliable test results after the expiration of their warranty period.

Development of genetically modified maize (&amp;lt;italic&amp;gt;Zea mays &amp;lt;/italic&amp;gt;L.) NK603 matrix reference materials

<p id="C3">The implementation of genetically modified organisms (GMO) safety management and labeling system requires standardized testing methods and reference materials (RMs). Furthermore, the RMs are the guarantee of obtaining accurate, reliable and comparable testing results. At present, genetically modified (GM) maize (<italic>Zea mays</italic> L.) NK603 has been approved to be imported as processing raw material in China, and its safety supervision urgently needs to prepare RMs. In this study, the heterozygous seeds of GM maize NK603 and the non-GM maize counterpart after identification were well milled and then gravimetrically mixed to prepare three levels of powder RMs according to the mass fractions of 60.0, 100.0, and 1000 mg g^-1. The homogeneity and stability test by duplex ddPCR method showed that the RMs of GM maize NK603 were homogenous and stable for not less than six months. The property values were collaboratively characterized by eight laboratories using duplex ddPCR method. The certified values together with their expanded uncertainties were (2.75±0.26)%, (4.68±0.39)%, and (51.8±3.7)%, respectively. The minimum sample intake was determined to be 100 mg. This batch of RMs can be used for the qualitative and quantitative detection of NK603 event in food and feed, as well as for the evaluation of GM maize NK603-specific assays and laboratory quality control.

Pre-analytical sample stabilization by different sampling devices for PCR-based COVID-19 diagnostics

The outbreak of the SARS-CoV-2 pandemic created an unprecedented requirement for diagnostic testing, challenging not only healthcare workers and laboratories, but also providers. Quantitative RT-PCR of various specimen types is considered the diagnostic gold standard for the detection of SARS-CoV-2, both in terms of sensitivity and specificity. The pre-analytical handling of patient specimens is a critical factor to ensure reliable and valid test results. Therefore, the effect of storage duration and temperature on SARS-CoV-2 RNA copy number stability was examined in various commercially available specimen collection, transport and storage devices for naso/oropharyngeal swabs and saliva. The swab specimen transport and storage devices tested showed no significant alteration of viral RNA copy numbers when stored at room temperature, except for one system when stored for up to 96 h. However, at 37 °C a significant reduction of detectable RNA was found in 3 out of 4 of the swab solutions tested. It was also found that detectability of viral RNA remained unchanged in all 7 saliva devices as well as in unstabilized saliva when stored for 96 h at room temperature, but one device showed marked RNA copy number loss at 37 °C. All tested saliva collection devices inhibited SARS-CoV-2 infectivity immediately, whereas SARS-CoV-2 remained infectious in the swab transport systems examined, which are designed to be used for viral or bacterial growth in cell culture systems.

Effect of varying storage time and temperature on unspun blood samples for prothrombin time and activated partial thromboplastin time in a tertiary hospital laboratory in the tropics

Introduction: Delays in the time of analysis of unspun blood samples stored at varying temperatures received in the laboratory pose a risk for unreliable prothrombin time (PT) and activated partial thromboplastin time (APTT) result; hence, consequent detrimental effect on patient care. This study's aim was thus to determine the optimal storage conditions and the potential effect of various storage times and temperatures on unspun samples for PT and APTT for a reliable test result. Materials and Methods: In a cross-sectional study, 33 eligible apparent healthy volunteers were recruited. Eighteen milliliters (ml) of venous blood were collected into 20 ml plastic bottles containing 2 ml of 0.109 M sodium citrate as an anticoagulant. Each citrated sample was separated into nine 2 ml aliquots. Baseline PT and APTT were determined with a coagulometer immediately and the remaining aliquots were analyzed after 3, 6, 12, and 24 h storage time at refrigerated (4°C) and room temperature (RT), respectively. The Statistical Package for the Social Sciences and Paired student t-test were used for statistical analysis. Results: At 24 h storage time at both RT and 4°C for PT, there was a statistically significant difference (P = 0.000). For APTT, a statistically significant difference was observed at 12 h (P = 0.009) and 24 h (P = 0.000) at RT whereas, at 4°C, all storage time had a statistically significant difference (P &lt; 0.05). Conclusion: Unspun blood samples can be stored maximally for 12 h at RT and 4°C for PT whereas it is 6 h at RT only for APTT.

Laser-textured High-throughput Hydrophobic/Superhydrophobic SERS platform for fish drugs residue detection

Surface-enhanced Raman Scattering (SERS) possesses unique advantages including convenient operation, label free, simple pretreatment process, non-destructive inspection and reliable test results. Aimed at practical applications, the SERS substrates need comprehensive properties in low-cost, rapid detection, high sensitivity, uniformity, stability and universality. Facile fabrication such as laser ablation and high-throughput detection can greatly reduce the cost and improve the detection efficiency. Meanwhile, superhydrophobic surfaces can increase the sensitivity and uniformity via evaporation enrichment. Herein, we report a patterned hydrophobic/superhydrophobic SERS platform, achieving the detection of 10-14mol/L Rhodamine 6G with an effect factor up to 2.1 × 1011 and high-throughput detection for at least nine different samples simultaneously. Notably, considering the abuse of hazardous fish drugs, we further apply this platform to detect crystal violet, malachite green, methylene blue, their mixtures and the crystal violet residue on contaminated fish scales. These results demonstrate that this SERS platform can not only maintain its relatively high sensitivity but also perform excellent distinguishing ability, offering valuable information on the application fields including food safety evaluation.

Rock Wettability Characteristics Of Some Indonesian Limestones Case Study: Baturaja Formation

Rock wettability plays a very important role in affecting various rock physical properties such as relative permeability and capillary pressure. Common practice at present is that carbonate rocks are assumed to be preferentially oil wet in nature. This assumption may prove fatal since the need of true knowledge over the real wettability for one’s carbonate reservoir is often neglected, and wettability aspect in reservoir modeling is in turn based on assumption. To prove over reliability of the assumption a study is carried out using information from 350 core samples taken from Baturaja Formation. The choice for the Baturaja limestone is basically based on the fact that it is a mature productive rock formation and its extensive spread into three of the most productive sedimentary basin in Indonesia, Northwest Java Basin, South Sumatra Basin, and Sunda Basin. The study proves that the assumption of the generally oil wet limestone does not apply for Baturaja limestone. The Baturaja limestone tend to exhibit, quantitatively, equality in their tendency towards oil wettability and water wettability and leave some proportion to neutral or mix wettability as well. However, when a more detailed comparison is made results show that qualitatively the limestone are indeed more inclined to oil wettability than water wettability even though this finding is insufficient to support a conclusion that the Baturaja limestone are specifically oil wet. Other finding from comparison with past studies also shows that limestone may behave in the way sandstones do. Both limestone and sandstones may vary in the same way and no assumption over their preferential wettability is justified without direct measurements. Wettability alteration as the result of hot core cleaning following the widely accepted standard procedure is also strongly indicated. It is therefore concluded that the practice has to be abandoned for a better and reliable laboratory testing results.

Experimental analysis and predictive modelling of linear viscoelastic response of asphalt mixture under dynamic shear loading

The use of predictive models can facilitate the inclusion of shear parameters in asphalt mixture evaluation and design processes. Unlike more extensively studied tension–compression models, the currently existing shear model, the Hirsch model, has unrealistic constants, particularly for the prediction of phase angle. Aiming at an improved predictive model in shear, this study employs a simple shear apparatus to experimentally analyse the linear viscoelastic properties of asphalt mixtures for road paving. Master curves were constructed and compared between different asphalt mixtures. Additionally, the test results were also analysed in the Black space and the Cole-Cole space. The dynamic shear response of asphalt mixtures was thereafter modelled on the basis of the Hirsch model. As the original model for phase angle prediction was found to be unrealistic, a particular focus in this study was put on identifying realistic empirical relationships for predicting the phase angle of asphalt mixtures in shear. More reliable shear test results of asphalt mixtures were used to calibrate the model, and extra test data were utilized to validate the calibrated model. It is indicated that the predictive model after calibration could deliver results of greatly improved accuracy, especially at the high-frequency and low-frequency ends. The analysis and modelling also leads to realistic empirical relationships for predicting the phase angle of asphalt mixtures in shear. The experimental verification confirms the good prediction accuracy of the calibrated model and proposed empirical relationships.