Evaluation Of Long-term Stability Research Articles

Evaluation of long-term stability of L-asparaginase encapsulated PLL-g-PEG nanoparticles in solution to aid in therapeutic delivery

Abstract L-asparaginase (L-ASNase) is a therapeutic enzyme that is widely used for the treatment of hematopoietic diseases such as acute lymphoblastic leukemia and lymphomas. L-ASNase destroys asparagine dependent tumors by degrading circulating L-asparagine and thereby destroying malignant cells. As a protein drug, L-ASNase carries a few inherent drawbacks including short circulating half-life, low stability, and low catalytic activity under physiological conditions. Moreover, due to the bacterial origin of L-ASNase used in treatments, there have been reports with high frequency of hypersensitivity reactions in patients. The use of this drug in adult cancer populations has largely been hindered not only due to its immunological side effects but also due to non-immunogenic toxicities such as pancreatitis, liver toxicities, coagulopathy, and neurotoxicity. Therefore, it is vital to find new methods to decrease its immunogenic/toxicity profile while increasing the stability and half-life. The purpose of this study is to achieve a new L-ASNase polymer nanocarrier to improve stability of the enzyme while masking it from the immune system of the host. We designed and characterized a nanoparticle (NP) where a poly-L-lysine-grafted-poly(ethylene) glycol co-polymer was used to encapsulate L-ASNase. The primary focus of the study was to evaluate the stability and encapsulation efficiency of this NP construct over time. There was no aggregation of NPs observed during the study period of 6 months in solution and NPs had a 0.436 mV surface charge. L-ASNase NPs showed a percent asparaginase activity of 31% compared to free L-ASNase. Under physiological conditions NPs were found to be intact and retained the encapsulated proteins for up to 6 months in solution. Together, these results demonstrate that L-ASNase loaded PLL-g-PEG NPs may serve as a fundamental platform to design nanocarriers to prolong stability in solution.

Long-term stability of a PTW 34070 large-area parallel ionization chamber in clinical proton scanning beams.

In the modeling of beam data for proton therapy planning systems, absolute dose measurements are performed utilizing a Bragg peak chamber (BPC), which is a parallel-plate ionization chamber. The long-term stability of the BPC is crucial for ensuring accurate absolute dose measurement. The study aims to assess the long-term stability of the BPC in clinical proton pencil beam scanning delivery. The long-term stability evaluation focused on the BPC-Type 34070 (PTW Freiburg, Germany), utilizing clinical proton scanning beams from December 2022 to November 2023. Monthly investigations were conducted to evaluate the response and cross-calibration factor of the BPC and a reference chamber, employing the spread-out Bragg peak (SOBP) field. Additionally, assessments were made regarding the BPC's response to monoenergetic beams, along with an examination of the impact of polarity and ion recombination on the BPC. The response and cross-calibration factor of the BPC varied up to 1.9% and 1.8%, respectively, while the response of the reference chamber remained within a 0.5% range. The BPC's response to the mono-energetic beams varied up to 2.0% across all energies, demonstrating similar variation trends in both the SOBP field and mono-energetic beams. Furthermore, the variations in polarity and ion recombination effect remained stable within a 0.4% range throughout the year. Notably, the reproducibility of the BPC remained high for each measurement conducted, whether for the SOBP field or mono-energetic beams, with a maximum deviation observed at 0.1%. The response and cross-calibration factor of the BPC demonstrated significant variations, with maximum changes of 1.9% and 1.8%, respectively. However, the reproducibility of the BPC remained consistently high for each measurement. It is recommended that when conducting absolute dose measurements using a BPC, its response should be compared and corrected against the reference chamber for each measurement.

Exploring the Dissolution, Solid-state Properties, and Long-term Storage Stability of Cryoprotectant-free Fenbendazole Nanoparticles.

Fenbendazole is an antiparasitic drug widely used in veterinary medicine to treat parasitic infections caused in animals like cattle, horses, sheep, and dogs. Recently, it has been repositioned as a potential alternative for cancer treatment. However, it is a highly hydrophobic molecule (0.9 ug/mL), which can compromise its dissolution rate and absorption. Thus, this work aimed to apply a nanotechnological approach to improve drug solubility and dissolution performance. Fenbendazole nanoparticles stabilized by different poloxamers were obtained by lyophilization without cryoprotectants. The behavior of the drug in the solid state was analyzed by X-ray diffractometry, differential scanning calorimetry, and infrared spectroscopy. The nanosystems were also evaluated for solubility and dissolution rate. A long-term stability evaluation was performed for three years at room temperature. The yields of the lyophilization ranged between 75 and 81% for each lot. The nanoparticles showed a submicron size (< 340 nm) and a low polydispersity depending on the stabilizer. The physicochemical properties of the prepared systems indicated a remarkable amorphization of the drug, which influenced its solubility and dissolution performance. The drug dissolution from both the fresh and aged nanosystems was significantly higher than that of the raw drug. In particular, nanoparticles prepared with poloxamer 407 showed no significant modifications in their particle size in three years of storage. Physical stability studies indicated that the obtained systems prepared with P188, P237, and P407 suffered certain recrystallization during long storage at 25 °C. These findings confirm that selected poloxamers exhibited an important effect in formulating fenbendazole nanosystems with improved dissolution.

Achieving partial nitrification by sludge treatment using sulfide: Optimal conditions determination, long-term stability evaluation and microbial mechanism exploration

This study proposes an innovative strategy for achieving PN in synthetic domestic wastewater by side-stream sludge treatment using sulfide as the sole control factor. By conducting controllable batch experiments and response surface analysis, optimal sulfide treatment conditions were firstly determined as 90 mg/L of sulfide, 7.5 of pH, 100 rpm of rotation and 12 h of treatment time. After treatment, half of ammonia oxidizing bacteria (AOB) activity remained, but nitrite oxidizing bacteria (NOB) activity was barely detected. Nitrite accumulation rate of long-term running PN steadily reached 83.9 % with 99.1 % of ammonia removal efficiency. Sulfide treatment increased community diversity and facilitated stability of microbiota functioning with PN phenotype, which might be sustained by the positive correlation between ammonia oxidation gene (amoA) and sulfur oxidation gene (soxB). Correspondingly, the network analysis identified the keystone microbial taxa of persistent PN microbiota as Nitrosomonas, Thauera, Truepera, Defluviimonas and Sulitalea in the later stage of long-term reactor.

Evaluation of Long-Term Stability in Single-Piece Implant Systems: An Original Research.

Because of its integrated design and possible benefits over conventional two-piece systems, single-piece implant systems have grown in favor in the field of dental implantology. There is, however, still a dearth of information about their long-term stability and clinical results. The purpose of this study was to assess the clinical results, such as implant survival rates, peri-implant tissue health, and marginal bone levels, to determine the long-term stability of single-piece implant systems. About 127 individuals who got single-piece implants at the tertiary care center were the subject of a retrospective analysis. Standardized procedures were followed for implant implantation, and patients were monitored for at least five years afterward. Through radiographic analysis and clinical tests, clinical indicators such as marginal bone levels, peri-implant tissue health, and implant survival rates were evaluated. With low marginal bone loss and good peri-implant tissue health, the research showed a high implant survival rate of 96.5%. A statistical study revealed significant relationships between marginal bone loss (P < 0.01), peri-implant tissue health (P < 0.05), and implant survival. In this study, single-piece implant devices showed good long-term durability and clinical results. These results confirm its effectiveness as a dependable dental rehabilitation alternative, highlighting the significance of preserving the health of the peri-implant tissue and reducing marginal bone loss to guarantee implant success.

Investigation on shakedown response-behavior of thawed subgrade soils under long-term traffic loading

The shakedown state of the subgrade is crucial for the sustainable design and long-term stability evaluation of pavement structures. In order to characterize the plastic deformation and shakedown behavior of subgrade soil in seasonal frozen regions, cyclic triaxial tests were conducted on the thawed subgrade soil after seven cycles of freeze-thaw. The influences of the numbers of cycle loading, the amplitude of cyclic deviator stress, and the confining stress were considered variables. The evolution features of accumulative plastic strain, accumulative plastic strain rate, and critical dynamic stress were experimentally analyzed. Based on the shakedown theory, the ensuing discoveries were that the accumulative plastic strain response-behavior of thawed subgrade soil was typically divided into plastic shakedown, plastic creep, and incremental collapse under the long-term cyclic loading. Furthermore, the shakedown standard for thawed subgrade soil was also proposed based on the evolution of the accumulative plastic strain rate. The critical dynamic stresses can be obtained by the proposal formula to determine the different plastic deformation ranges.

Commercial human frozen plasmas for local, cross-site and long-term comparability of coagulation analysers.

Laboratory compliance implies to correlate instruments for coagulation parameter with a wide range of measure using patient samples or commercialized sets of frozen plasmas. The aim of this study was to evaluate the intra, inter-reproducibility and long-term stability of ExpertCor Routine (ECR) plasma sets (Stago) on different parameters. The study was realized in two laboratories on four different instruments. Inter-site and intra-site correlation of ECR sets for PT, aPTT, Fibrinogen, INR, factor V (FV) UFH and LMWH anti-Xa and intra-reproducibility of DDimer (DDI), factor VIII (FVIII:C) and antithrombin (AT) assays were tested. To evaluate ECR long-term stability, samples were tested until 180 after delivery in one laboratory. Intra-site evaluation correlation coefficients is around 1. All predefined criteria to fulfil good comparability between inter-site instruments are met with Passing slopes between 0.9 and 1.1 and intercepts ranging from -0.62 to 2.83%. Long-term stability evaluation does not show any deviation over 180 days for aPTT, fibrinogen, DDI, UFH, LMWH but a drift for FV with STA-NeoPTimal reagent. On contrary, AT and FVIII:C are not stable. PT in second has an excellent stability unlike PT in percentage. Our study validates the use of ECR sets for correlation between instruments and inter-sites agreement, as for parameters claimed on the products than for factor V and FVIII:C. The evaluation of stability confirming the possible extension of use for 180 days after delivery except for FVIII:C and AT. These plasmas sets are an excellent alternative to local plasma patient use to perform instrument comparison.

An improved Burgers creep model of coal based on fractional-order

The instability and destruction of various types of coal pillars left in deep underground mining are frequently attributed to cumulative creep deformation exceeding the permissible limit, with high in situ stress playing a critical role in this phenomenon. To understand the complicated creep behavior of coal, triaxial compression creep tests were conducted. It has been proven that the coal specimens subjected to high confining pressure exhibit typical three-stage creep characteristics. Furthermore, with the increase in confining pressure, the creep threshold value increases while the creep threshold coefficient decreases. By fitting the creep strain-time results, an improved Burgers creep model based on fractional-order was proposed. This model can describe the primary, secondary, and tertiary stages and reflect the nonlinear behavior, contributing to the understanding of the long-term stability evaluation of deep coal pillars.

A critical review on In2S3-based nanomaterial for emerging contaminants elimination through integrated adsorption-degradation technique: Effect of reaction parameters and co-existing species

The possibility of combined adsorption-degradation processes in wastewater treatment using nanomaterials based on indium sulfide (In2S3) is examined in this review paper. Regarding the synergistic adsorption and degradation of pollutants, In2S3 performs exceptionally well, making it a suitable choice for wastewater remediation. Insights have been given to the pollutant removal mechanism through this integrated technique. The synergistic removal process is affected by several operational factors, including pH, catalyst dose, pollutant concentration, and contact duration. This analysis highlights the significance of optimizing these parameters for optimal contaminant removal efficiency. The influence of co-existing species, including cations, anions, and organic compounds, on the integrated elimination process is further highlighted by a discussion of their role. Future research directions are suggested, including a better comprehension of underlying processes, investigation of hybrid nanocomposites, and evaluation of long-term stability and recyclability to enhance the applicability of In2S3-based nanomaterials. This study aids in the creation of effective and long-lasting wastewater treatment methods by using the potential of In2S3-based nanomaterials.

An eco-friendly system for stabilization of retinol: Astep towards attending performance with improved environmental respect.

Retinol (Vitamin A) is one of the most effective molecules for the treatment of skin aging. However, it degrades rapidly under the influence of light, oxygen, metal ions, and oxidizing agents. To prevent this, stabilizing systems are used commonly. Notably, butylated hydroxytoluene (2,6-di-tert-butyl-p-cresol) (BHT) and ethylenediaminetetraacetic acid (EDTA) salts exhibit excellent antioxidant and metal-chelating properties but are not eco-friendly. In this study, our goal was to develop a new eco-friendly stabilization system for retinol-based formulations such that the system does not interfere with retinol skin absorption, nor its clinical efficacy. An evaluation tool called the Sustainable Product Optimization Tool (SPOT) was used to assess the environmental performance of formulations containing retinol and the various stabilizers investigated. Accelerated stability tests were performed on formulations stored for 2 months at 4 and 45°C (ISO/TR Standard 18811 2018 directives). Long-term stability evaluation was done on formulations stored for 24-months at room temperature. Retinol skin absorption was assessed by the Franz cell method using human skin explants (OECD guideline 428). Finally, a clinical study was performed to evaluate the cosmetic performance of a 0.3% stabilized retinol formulation. N,N'-ethylenediamine disuccinic acid ([S,S]-EDDS isomer) and pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate) (PBHC) showed higher biodegradability and a reduced water footprint compared with those of BHT and EDTA. The SPOT simulation gave [S,S]-EDDS + PBHC a score of 10 versus 8.84 for EDTA + BHT. Moreover, [S,S]-EDDS + PBHC better controlled the chemical degradation of retinol compared with EDTA + BHT. Retinol skin absorption was also achieved in the case of a formulation containing [S,S]-EDDS + PBHC, and several skin attributes improved significantly after 12 weeks of product use, with over 75% of the panel perceiving benefits. Regarding retinol stabilization, the PBHC + [S,S]-EDDS combination is an eco-friendlier and more effective alternative to BHT + EDTA.

Long-term stability analysis and evaluation of horizontal salt cavern gas storage

To study the long-term stability of horizontal salt cavern gas storage, the numerical simulation method was adopted to analyze the long-term stability of horizontal elliptical cylindrical salt cavern gas storage under different influence factors. The reasonable axial length, minimum internal pressure and pillar width of salt cavern gas storage were determined by comprehensively comparing the numerical simulation results, such as surrounding rock deformation, volume shrinkage and plastic zone distribution range. On this basis, the CRITIC method was used to calculate the weights of influence indexes of the long-term stability for salt cavern gas storage and determine the importance ranking of these indexes. Subsequently, an improved stability evaluation system was proposed. Finally, the catastrophe model of the stability influence indexes of the salt cavern gas storage was classified, then the long-term stability evaluation model based on catastrophe progression method was built, and the stability of different salt cavern gas storage cases was quantitatively evaluated by the model. The results indicate that the evaluation results of the established model are well consistent with the numerical simulation results and the stability grade of the horizontal elliptical cylindrical salt cavern gas storage is Grade II, namely the horizontal salt caverns are in stable state for an operation time of 30 years.

Fast gas sensing scheme with multi-component gas measurement capacity based on non-dispersive frequency comb spectroscopy (ND-FCS).

A fast gas sensing scheme based on a non-dispersive frequency comb spectroscopy (ND-FCS) is proposed and experimentally demonstrated. Its capacity for multi-component gas measurement is experimentally investigated as well, by using the time-division-multiplexing (TDM) method to realize specific wavelength selection of the fiber laser optical frequency comb (OFC). A dual-channel optical fiber sensing scheme is established with a sensing path consisting of a multi-pass gas cell (MPGC), and a reference path with a calibrated signal to track the repetition frequency drift of the OFC for a real-time lock-in compensation and system stabilization. The long-term stability evaluation and the simultaneous dynamic monitoring are carried out, with the target gases of ammonia (NH3), carbon monoxide (CO) and carbon dioxide (CO2). The fast CO2 detection in human breath is also conducted. The experimental results show that at an integration time of 10 ms, the detection limits of the three species are evaluated to be 0.0048%, 0.1869% and 0.0467%, respectively. A low minimum detectable absorbance (MDA) down to 2.8 × 10-4 can be achieved and a dynamic response with millisecond time can be realized. Our proposed ND-FCS exhibits excellent gas sensing performance with merits of high sensitivity, fast response and long-term stability. It also shows great potential for multi-component gas monitoring in atmospheric monitoring applications.

Influences of Flow Channel on Electrochemical Characteristics of Polymer Electrolyte Fuel Cells Humidified with NaCl Contained H2O

In this study, the effects of flow field types on the electrochemical properties of polymer electrolyte membrane fuel cells (PEMFCs) humidified with NaCl solution are systematically investigated. The parallel flow field and serpentine flow field were used to investigate the PEMFCs. Long-term stability was evaluated for 20 h using chronoamperometry. Fuel cells with both parallel and serpentine flow fields showed a decrease in performance because of the NaCl solution. Interestingly, the PEMFC with the serpentine flow field showed significantly more severe degradation during long-term stability evaluation compared to the fuel cell with the parallel flow field. Electrochemical impedance spectroscopy analysis showed that a significant increase in faradaic resistance caused the degradation of the performance. After long-term stability examinations, regenerations of fuel cells were performed with deionized water at a constant voltage (0.4 V). After the regeneration, the performance of the fuel cells with the serpentine flow field was improved more (52.96%) than the PEMFC with the parallel flow field (1.22%).

Study on creep characteristics and fractional creep damage constitutive model of limestone under thermal-mechanical action

To study influence of thermal-mechanical action on creep for the geothermal wellbore, Dalian limestone was taken as the research object, and triaxial creep tests were carried out on samples under different temperatures and the effects of different temperatures on the creep deformation, creep rate and long-term strength of limestone are discussed. The test results show that the creep process of limestone under thermal-mechanical action shows three distinct phases. As the temperature increases, the creep time and long-term strength gradually decrease. The macroscopic failure modes of limestone under different temperatures are shear failure and the fracture surface is more obvious. Meanwhile, based on the principle of statistical damage and fractional calculus, the damage body under high temperature is proposed, and a fractional creep damage model that can characterize the triaxial creep mechanical behavior of limestone under different temperatures is constructed. The reasonableness of the model is proved by comparing. The parameters analysis shows that the fractional order δ mainly affects the creep rate, which is expressed in the stable and accelerated phases. The aging damage parameter λ is related to the time coordinate scale. The research results in this paper can provide a certain guiding significance for the long-term stability evaluation of the surrounding rock of the geothermal wellbore.

Long-term stability analysis and evaluation of salt cavern compressed air energy storage power plant under creep-fatigue interaction

To investigate the influence of the fatigue effect of salt rock on the long-term stability of the compressed air energy storage power plant, the numerical simulation method was used to analyze the long-term stability of the energy storage under the conditions of the fatigue effect is considered (the creep-fatigue interaction of salt rock stratum is considered) and not considered (only the creep behavior of salt rock stratum is considered). The numerical calculation results show that when the fatigue effect is considered, the deformation of the surrounding rock and the cavern volume shrinkage are far greater than the corresponding values when the fatigue effect is not considered, indicating that the fatigue effect has an important impact on the stability of the storage. Then based on the numerical simulation results, the minimum pressure, maximum pressure and pillar width of the salt cavern compressed air energy storage power plant were determined by contrasting the displacement of the surrounding rock, the cavern volume shrinkage and the extended range of the plastic zone. Finally, a long-term stability evaluation system for the salt cavern compressed air energy storage power plant was established based on the analytic hierarchy process method, and the long-term stability was quantitatively evaluated using the fuzzy evaluation method. The results show that the stability level of the double salt caverns compressed air energy storage power plant is Level II, indicating that they are in stable state.

Chemical and mechanical accelerated and long-term stability evaluation of sunscreen formulation containing grape seed extract.

Sunscreens and catechins from grape seed extract (GSE) are sensitive to various environmental factors and undergo certain changes over time that might affect the effectiveness of the final product. To this date, effects of thermal storage conditions have not been sufficiently addressed to guarantee the long-term stability of sunscreen formulations. To study the chemical and mechanical accelerated and long-term stability of sunscreen formulation containing GSE at the Climatic Zone IVb conditions. Stability studies were performed for 6months for accelerated stability study at 30°C ± 2 and 50°C ± 2, 75 ± 5% relative humidity; and long-term stability study at 5°C ± 5. The quantification of constituents of three formulations: sunscreen with GSE, cream with UV filters only, and cream with GSE only was performed by high-performance liquid chromatography. In vitro spectrophotometry was used to determine changes in sun protection effectiveness through SPF and UVAPF values. Mechanical stability was evaluated by textural and rheological analyzes. All tested formulations were less stable at high-temperature conditions. The contents of catechin (С) and epicatechin (EC) in sunscreen with GSE were reduced to 37% and 50% at 50°C, respectively, whereas UV filters appeared to be stable. However, despite the significant reduction in catechins over time, polyphenols in GSE remained unchanged at different stored conditions. The SPF values and water resistance of sunscreen with GSE were maintained throughout the study. A current in vitro study has shown that sunscreen with GSE is a value-added anti-aging ingredient in sunscreen formulation because its polyphenolic composition as well as SPF values and water resistance were maintained under all temperature conditions over time.

Long-term stability evaluation of reduced Cr-containing waste residue under aging test and the underlying Cr reoxidation mechanism

The reduction of highly toxic Cr(VI) to immobilized Cr(III) using ferrite has been widely used to diminish the toxicity of Cr(VI)-containing waste residues (CWR). However, the Cr(III) in the reduced Cr-containing waste residues (RCWR) may be reoxidized into Cr(VI), posing potential environmental risks. In this work, the long-term stability of the real RCWR samples were evaluated through aging test, showing the reoxidation of Cr(III) to Cr(VI). In order to reveal the underlying mechanism of the Cr(III) reoxidation, FexCr1-x(OH)3, a common Cr(III)-containing mineral in the RCWR, was synthesized and used as simulated RCWR, in which the release and oxidation mechanism of Cr(III) were investigated under the influence of ambient conditions (such as sunshine irradiation and different pH). The results showed that FexCr1-x(OH)3 was stable at pH of 5 and 7, but became unstable at pH of 3 and pH of 9 ∼ 11. Specifically, the dissolution of Cr(III) and Fe(III) from FexCr1-x(OH)3 was greatly promoted by simulated sunshine irradiation at pH 3, while the oxidation rate of Cr(III) were increased by sunshine irradiation with the increasing pH value from 9 to 11. The mechanism study showed that Fe0.5Cr0.5(OH)3 is a n-type semiconductor with a band gap of 2.06 eV. When irradiated by light with wavelength below 602 nm, photo-generated electrons and holes can form and immigrate to the surface of particles. The promoted dissolution of Cr(III) at pH of 3 might be ascribed to ·OH deriving from photoexcitation of Fe0.5Cr0.5(OH)3, while the oxidation of Cr(III) to Cr(VI) at pH of 9 ∼ 11 may be related to photo-generated holes. This work contributes to clarifying the migration and transformation of Cr in FexCr1-x(OH)3 and provides a theoretical supporting for the management and disposal of CWR.

Light-initiated chemiluminescent assay of 17β-estradiol metrological traceability system established by manufacturer according to ISO17511:2020 and basic performance evaluation performed by clinical end-users.

BackgroundIn order to ensure the accuracy of the product, we established 1st model of metrological traceability hierarchy for light‐initiated chemiluminescent assay (LICA) of 17β‐estradiol (E2) at the manufacturer, based on International Organization for Standardization (ISO) 17511:2020. Moreover, we verified/validated the basic performance (such as matrix effect and long‐term stability of end‐user IVD MD calibrator, precision, linearity interval, accuracy/ trueness, and detection capability) at the clinical end‐user.MethodsHuman serum samples were used in this study. E2 was detected by mass spectrometry (MS) and LICA. The metrological traceability of LICA for E2 was established according to ISO 17511: 2020 standards, and pools of human samples were used as the m.3. secondary calibrator. Precision was validated according to Clinical and Laboratory Standards Institute (CLSI) EP05‐A3. The linear interval was verified according to CLSI EP06‐ED2. Comparison of accuracy and trueness of E2 with MS and Roche according to CLSI EP09‐A3. The detection capability was validated according to EP17‐A2. Matrix effect and long‐term stability evaluation of end‐user IVD MD calibrator were carried out according to CLSI EP14‐A2, EP25‐A. Statistical software was used for data analyses.ResultsThe use of pools of human samples and fine adjusting calibrators ensured the accuracy of end‐user test results. The metrological traceability of LICA for E2 was established. It showed excellent precision, meeting the requirements of allowable imprecision (7.5%). The allowable deviation from linearity (ADL) of 5% was allowed to show a good linear interval (12.52–4167.25 pg/ml). The accuracy/ trueness was verified, and relative deviation in the medical decision level met the performance specification of 10.03% compared with MS or Roche. The validated limit of blank, limit of detection, and limit of quantitation of E2 were 4.95 pg/ml, 8.93 pg/ml, and 9.88 pg/ml, respectively (the allowed imprecision is 20.00%). The interference rate of E2 ranged from −5.5% to 6.6%.ConclusionLICA showed high sensitivity, high specificity, excellent precision, wide linearity interval, IVD MD calibrator has long‐term stability, and no matrix effect. The metrological traceability of E2 established by using pools of human samples as M.3. can deliver accuracy to the end‐user IVD MD and show good consistency with MS and Roche.

Evaluation of long-term stability of SARS-CoV-2 nucleic acid extracted from human nasopharyngeal samples

The maintenance of SARS-Cov-2 RNA samples poses a new challenge for laboratories and researchers. In addition, it is a requirement in order to identify what strain of the new coronavirus is predominant in a region, for instance. Therefore, it is a must to keep the quality and viability of stored RNA to respond to this and other valid questions. In other to test the quality of our samples and storing protocols, we randomly checked RNA samples four different times over one year using a second RT-PCR assay after the first test. The virus genes, N1 and N2, showed no significant increase in the media of the CT value between the first assay and subsequent times with p > 0.05. However, the human RP gene showed differences in the first three times analyzed, but within the acceptable sample cut-off, according to the test manufacturer. After one year, the RNA extracted from human nasopharyngeal specimens are viable to detect the virus SARS-CoV-2 genes with minor changes.

The relationship between microstructure evolution and impact toughness degeneration of alloy 617B during long term aging

Impact toughness degeneration and microstructure evolution of alloy 617B during 650–725°C long-term aging for up to 12,000 h were investigated in present work. It is found that impact toughness decreases apparently even after just 20 h aging in the temperature range of 650–725°C and keeps decreasing with prolonging aging time. Hence, detailed microstructure observation and mechanical property tests were carried out to reveal the essence of impact toughness degeneration during long-term aging. And the reason is confirmed to be the combination effect of plasticity evolution and grain boundary carbide coarsening. The degeneration of impact toughness with prolonging aging time can be divided into rapid decrease stage, slow decrease stage and stable stage. The decrease of plasticity in the major reason for rapid impact toughness degeneration in the initial stage of aging. Grain boundary carbide coarsens obviously during aging and tends to be continuous. This is the major reason for the slow and continuous decrease of impact toughness in the slow decrease stage. Finally, plasticity and grain boundary carbide change little, resulting in the stable stage of impact toughness evolution. Enough attention should be paid on impact toughness degeneration in the evaluation of long-term stability.