Bottom Of Tube Research Articles

Dispersive solid phase extraction of chloramphenicol and florfenicol in honey sample performed in narrow bore tube with the aid of magnetic ionic liquids prior to HPLC-DAD analysis

The precedence of high levels of antibiotics in animal-derived foods such as honey poses a significant food safety risk. Therefore, the development of an accurate, and reliable method for determining these residues is crucial. In this study, a new extraction method was proposed for the simultaneous determination of chloramphenicol and florfenicol residues in honey samples prior to high performance liquid chromatography analysis. The method involved using amino-functionalized UiO-66 metal–organic framework (NH2-UiO-66) as a sorbent in a narrow bore tube. To begin, the solution was placed into a narrow bore tube and the pH was adjusted to 6. Then, 100 mg of the sorbent was added to the solution. The particles were slowly passed through the solution and collected in the tube bottom. After removing the supernatant phase, 55 µL of 1-butyl-3-methylimidazolium tetrachloroferrate (III) magnetic ionic liquid was used as the elution solvent under sonication for 3 min. The optimized method exhibited low limits of detection (0.19 and 0.44 ng g−1) and quantification (0.63 and 1.4 ng g−1), good extraction recovery (81 and 74 %), and good linearity of the calibration curve (r2 ≥ 0.996) over the ranges of 1.2–500 and 2.4–500 ng g−1 for florfenicol and chloramphenicol, respectively. Precision was satisfactory, with relative standard deviations ≤8.1 % for both intra- and inter-day precisions. The developed method was done on ten honey samples and chloramphenicol was found in five samples.

B-310 Freezing and thawing serum without mixing prior to analysis causes false low Thyroglobulin results

Abstract Background Thyroglobulin (Tg), a glycoprotein that is synthesized in follicular cells of the thyroid gland, is the precursor of Thyroxin (T4) and Triiodothyronine (T3). Tg is a biomarker used for many clinical conditions, including monitoring for recurrence in patients with differentiated thyroid carcinoma. Typically, Tg levels drop to very low or undetectable levels after surgical excision and/or radioiodine ablation of the thyroid, with post-operative levels greater than 1-2 ng/ml indicating potential disease recurrence. Discordant Tg results in a patient sample were identified during a quality check of Tg results. This study investigates the root of cause of the discrepant Tg results. Given that: 1) Tg analyses were performed twice a week at our laboratory due to low daily test volume and patients’ samples received on an unanalytical day were stored at -20°C until analysis; 2) Tg analyses were performed by various medical technologists; 3) sample mixation prior to analysis was not routine practice for our automated laboratory, we hypothesized that the discrepancy was due to inconsistent sample handling, e.g., mixation vs unmixation prior to analysis. Methods Analysis of the daily QC and PT results in the period of the incident occurence ruled out causes in analytical phase. We split 52 de-identified patient serum samples into two equal aliquots and subsequently stored both aliquots at -20°C for 48 hours. Both aliquots of each sample were thawed at room temperature for 1 hour. One of the aliquots was analyzed for Tg without mixing, and the other was analyzed after mixing using a Vortexer for 4 seconds at 250 xg. To investigate if Tg concentrations form a gradient from the top to the bottom of a red-top vacutainer tube, five patient samples with Tg at 2.59, 2.79, 2.92, 52.37 and 144.12 ng/mL were thawed without mixing following storage at -20°C for 48 hours. Five layer (600 μl/layer) aliquots were carefully and sequentially taken from top to bottom for each specimen, and the Tg concentration in the aliquot of each layer was determined using the Beckman Coulter Access-2 Immunoassay. Results Of the 52 patients samples, 14 Tg results were excluded from statistical analysis due to exceeding the assay dynamic range (2 above and 12 below the upper and low limits, respectively). Analysis of the remaining 38 patient samples showed the mean of Tg concentrations was 22.8% (SD 18%) higher in mixed samples than the un-mixed samples. Regression analysis showed an R2 = 0.9976 (Mixed Tg = 1.1523 x Un-mixed + 0.4174, range 0.1 - 275.7 ng/mL, intercept 95%CI -0.721 to 1.556, slop 95%CI 1.1331 to 1.1715, p-value <0.001). Results of Tg gradient analysis showed significant higher Tg values in the 2nd, 3rd, 4th and 5th than the 1st layer by 26% (SD 11%), 63% (26%), 112% (57%), and 160% (76%), respectively. Conclusions False Tg values were found in samples without mixing before analysis after thawing from frozen state, due to formation of Tg concentration gradient in test tube. For obtaining reliable results, samples must be mixed before analysis when thawed from frozen storage.

Unveiling the inhibition of high-pressure CO2 flow accelerated corrosion at gradual contraction and gradual expansion tubings

The different inhibition behavior of imidazoline quaternary ammonium salt for high-pressure CO2 flow accelerated corrosion of carbon steel gradual contraction and gradual expansion tubings was unveiled combing high pressure dynamic in situ electrochemical methods and microstructure characteristics analysis. It is manifested that there is no noticeable inhibition effect in high CO2 partial pressure environments at extremely low inhibitor concentration. At low inhibitor concentration, the polarization resistance and inhibition efficiency increase firstly and then decrease along the flowing direction of gradual contraction tubing. However, the polarization resistance generally drops along the gradual expansion tubing. As the inhibitor concentration of the corrosion inhibitor is further increased, the polarization resistance and inhibition efficiency are reduced in a whole along the gradual contraction tubing. Nevertheless, the polarization resistance is raised, followed by a fall along the flowing direction of gradual expansion tubing. The inhibition effect at the top and the bottom of gradual contraction tubing exhibits symmetry while it is asymmetrical at the top and the bottom of inclination section in gradual expansion tubing. The distinct inhibition effect at different inhibitor concentration is relevant to flow characteristics of fluid at gradual contraction tubing and gradual expansion tubing. The findings could provide valuable guidance for the protection of flow accelerated corrosion at gradual contraction tubing and gradual expansion tubing under high CO2 partial pressure conditions.

Effect of liquid elasticity on transient cavitation bubbles in the tube

We investigate the effect of liquid elasticity on the transient cavitation bubbles confined in a tube both experimentally and theoretically. In experiments, the tube-arrest apparatus is used to generate cavitation bubbles near the tube bottom with various polyethylene oxide solutions. Our experiments show that bubble dynamics, particularly the maximum bubble length, are significantly influenced by liquid elasticity. We establish a double oscillator model for the liquid column to explain the experimental results and predict the bubble dynamics over a broader range. Finally, we propose that the reciprocal of the cavitation number Ca2 and prR/k determine the regimes of the liquid column separation, where pr is the reference pressure, R is tube radius, and k is the “stiffness coefficient” of the liquid column. Our work provides a quantitative scaling of the dynamics of large cylindrical cavitation bubbles in viscoelastic liquids during the transient process.

ASCARIS SUUM EGG RECOVERY FROM SLUDGE SAMPLES AFTER PHASE EXTRACTION.

Some helminth test methods for sanitation samples include a phase extraction step to reduce lipid content and final pellet size before microscopy. Hydrophilic and lipophilic solutions are used to create 2 phases, with a plug of organic material or debris in between, whilst eggs are supposedly compacted at the bottom of the test tube. We tested 10% formalin, acetoacetic buffer, and acid alcohol as the hydrophilic solutions, and ethyl acetate and diethyl ether as the lipophilic solvents for egg recoverability from water, primary sludge, and fatty sludge. Normally, the supernatant and debris plug are discarded and the sedimented pellet of eggs is microscopically examined. We, however, also collected the entire supernatant plus debris plug to determine where eggs were possibly lost. We found that eggs were lost when samples were extracted with 10% formalin + ethyl acetate, 10% formalin + diethyl ether, acetoacetic buffer + ethyl acetate, and acetoacetic buffer + diethyl ether combinations (<50% egg recovery). Acid alcohol + ethyl acetate resulted in 93.2, 89.8, and 57.3% egg recovery in the pellet of water, primary sludge, and fatty sludge, respectively; however, the size of the final pellet was not reduced, defeating the purpose of the extraction step. We thus recommend that this step be excluded.

Ultrasensitive Detection of Prostate Specific Antigen by an Unlabeled Fluorescence Aptasensor Based on the AIE Effect.

The accurate and sensitive detection of prostate specific antigen (PSA) is vital for the early diagnosis and treatment of prostate cancer. To this end, an unlabeled fluorescent aptasensor was constructed by using a novel Compound B {1,1'-(1,4-phenylene) bis(3-ethyl-1H-imidazol-3-ium) iodide} with aggregation-induced emission (AIE) activity as a fluorescence signal and NH2-Fe3O4 particle as an adsorption platform. Compound B could combine with prostate specific antigen aptamers (PSA-Apt) to form a PSA-Apt/B complex, which further generated the AIE effect. Then, PSA was added to the PSA-Apt/B solution. PSA combined with PSA-Apt/B to form the PSA-Apt/B/PSA complex. Next, NH2-Fe3O4 magnetic particles were added to the solution. Given that PSA-Apt/B/PSA would no longer combine with NH2-Fe3O4 magnetic particles, the PSA-Apt/B/PSA complex remained in the supernate after magnet separation, and the supernate showed strong fluorescence (I). When no PSA was added to the PSA-Apt/B solution, PSA-Apt/B could combine with NH2-Fe3O4 magnetic particles and would be sucked into the bottom of the test tube by magnet, and the supernate would show weak fluorescence (I0). Result showed that the difference between the above-mentioned two fluorescence values (∆I = I - I0) had an excellent linear relationship with the PSA concentration within the concentration range of 0.01-10ng/mL, and its limit of detection was 3pg/mL (S/N = 3). In addition, the sensor has high accuracy and can be directly used to test PSA in actual serum samples.

Polysaccharide intercellular adhesin and proper phospholipid composition are important for aggregation in Tetragenococcus halophilus SL10.

Aggregating strains of Tetragenococcus halophilus tend to be trapped during soy sauce mash-pressing process and are, therefore, critical for clear soy sauce production. However, the precise molecular mechanism involved in T. halophilus aggregation remains elusive. In previous studies, we isolated a number of aggregating strains, including T. halophilus AB4 and AL1, and showed that a cell surface proteinaceous aggregation factor is responsible for their aggregation phenotype. In the present study, we explored the role of polysaccharide intercellular adhesin (PIA) in aggregate formation in T. halophilus SL10, isolated from soy sauce. SL10 exhibited similar aggregation to AB4 and AL1 but formed a non-uniform precipitate with distinctive wrinkles at the bottom of the test tube, unlike AB4 and AL1. Insertion sequence mutations in each gene of the ica operon diminished aggregation and PIA production, highlighting the critical role of IcaADBC-mediated PIA production in T. halophilus aggregation. Furthermore, two non-aggregating cardiolipin synthase (cls) gene mutants with intact ica operon did not produce detectable PIA. Phospholipid composition analysis in cls mutants revealed a decrease in cardiolipin and an increase in phosphatidylglycerol levels, highlighting the association between phospholipid composition and PIA production. These findings provide evidence for the pivotal role of cls in PIA-mediated aggregation and lay the foundation for future studies to understand the intricate networks of the multiple aggregation factors governing microbial aggregation.IMPORTANCEAggregation, commonly observed in various microbes, triggers biofilm formation in pathogenic variants and plays a beneficial role in efficient food production in those used for food production. Here, we showed that Tetragenococcus halophilus, a microorganism used in soy sauce fermentation, forms aggregates in a polysaccharide intercellular adhesin (PIA)-mediated manner. Additionally, we unveiled the relationship between phospholipid composition and PIA production. This study provides evidence for the presence of aggregation factors in T. halophilus other than the proteinaceous aggregation factor and suggests that further understanding of the coordinated action of these factors may improve clarified soy sauce production.

Study of cooling experiment and simulation for edible oil storage

This paper proposes a refrigerant cooling method using an inner tube in a storage tank to improve the cooling performance and thermal uniformity during the storing of edible oil. With a prototype of an oil tank in Central Grain Reserve of Zhenjiang, the experimental oil tank was built in a scale of 50:1. Both natural and manual cooling experiments were carried out for the experimental tank. The manual cooling process involved two supplying modes for the refrigerant tube (top and bottom) and four different refrigerant temperatures (10 ℃, 12 ℃, 14 ℃, 16 ℃). The experimental results show that, compared with natural cooling, manual cooling can effectively reduce the temperature difference and thermal stratification between upper and lower layers. The temperature difference is 6.79 ℃, 1.93 ℃, and 3.67 ℃ for the natural cooling, manual top supplying, and manual bottom supplying mode, respectively. Furthermore, for the two manual modes, the cooling efficiency of bottom supplying is 21.4% higher than that of the top supplying, and the average oil temperature drops by 0.8–1 ℃. Based on experimental results, different working conditions (20, 40, and 60 ml/s) were simulated to determine the optimal flow rate for bottom supplying mode. The simulation results indicate that the low flow rate (20 ml/s) corresponds to the best thermal uniformity, and the maximum temperature has no obvious change under different flow rate conditions. Therefore, it is not necessary to increase the flow rate to improve cooling efficiency considering the rising energy consumption.

CRISPR/Cas12a‐loaded intelligent DNA hydrogel for universal and ultrasensitive exosome assay

AbstractTumor‐derived exosomes are crucial for early non‐invasive and accurate tumor diagnosis in clinical diagnostics. The development of highly sensitive, simple, and intuitive exosome assays has sparked a research upsurge in clinical diagnostics. Here, we develop a bio‐responsive intelligent DNA hydrogel loaded with CRISPR/Cas12a for universal and ultrasensitive detection of the exosomes. The aptamer serves as the target response unit and switch, competitively disintegrating the region of the DNA linkers and then Cas12a/crRNA was released and activated, resulting in a high fluorescent intensity for exosome detection at the detection limit of 119 particles/μL. Moreover, a constructed colorimetric tube is made by loading a colorimetric filter membrane on the tube lid and intelligent DNA hydrogel on the tube bottom, which enables one‐pot portable colorimetric detection. Without the need for laboratory instruments and professionals, this strategy allows for naked eye detection with limit of detection as low as 104 particles/μL, and shows great applicability in distinguishing between healthy individuals, pretreatment patients, and post‐treatment patients after obtaining a testable analyte. In this study, an ultrasensitive detection platform for exosomes that enables one‐step sensing and dual signal output was introduced. The findings here suggest that this platform is a promising tool for the application of liquid biopsy based on exosomes in clinical diagnosis.

Effect of Wettability Gradient on the Scale Formation in Falling Film Flow

Abstract Mitigation of scale formation and performance degradation remains a vital challenge for falling film evaporators in various industries. In this work, an experimental study of falling film flow on a horizontal tube is conducted to investigate the effects of wettability gradients on thermal, hydraulic, and fouling behavior. It is revealed that certain hydrophobic coating patterns, such as strip, ring, and grid patterns, lead to unwetted heat transfer area, which results in decreased heat transfer compared to fully wetted plain tube. By adjusting the geometry and position of the wettability gradient, the hybrid coating demonstrates improved heat transfer performance. Based on the characteristics of horizontal tube falling film flow, impinging jet, thin film flow, and liquid retention at the tube bottom, a hybrid coating pattern is developed to improve surface wetting and mitigate the scaling coverage. It is revealed that scale deposition is regulated by wettability gradient. Crystals tend to be dense and compact in hydrophilic areas, while they appear scattered or even absent in hydrophobic regions, depending on the dimension of the hydrophobic area. While at the hydrophilic/hydrophobic boundary, a noticeable scale thickness step is observed, which raises the potential for self-cleaning. The balance of minimization of scaling layer coverage and maximization of wetting area requires an optimal design in coating dimensions, for which a systemic study of both flow dynamics and fouling characteristics on the falling film is necessary in the future.

Measuring the refraction index of luminescent carbon nanodots forming Gaussian beam using the tracker software

Nanotechnology is currently regarded as one of the fastest-growing technologies. Equipping students with some understanding of nanotechnology in relation to physics ideas may trigger their interest and inspire them to learn physics. This study is aimed to measure the refraction index of Cdots solution using the Gaussian beam and Tracker software. The method used in this research is quantitative descriptive method with the stages of research that include designing, construction, developing, and testing the measuring instrument. The procedure in this study begins by preparing the Cdots solution from cajuput oil (CJO) distillation wastes. The Cdots are then characterized using the UV-visible (UV-Vis), photoluminescence (PL), time resolved-PL (TRPL), and Fourier transform infrared (FTIR) spectroscopies. The Cdots solution is then put into a reaction tube with solution height variation. The violet/UV laser pointer is exposed upward towards the Cdots solution from the bottom of the reaction tube producing a Gaussian beam inside the reaction tube. The Gaussian beam is then photographed, which then the format is converted into a video format. The video format of the Gaussian beam is analyzed using the Tracker software. The characterizations of the Cdots show i) an absorption peak at a wavelength of 216.0 nm, ii) an emission peak at 512.29 nm indicating cyan luminescence, iii) an electronic lifetime of 51.3 ns, and iii) functional groups of O-H; C=C; and C=O. Moreover, the Gaussian beams are formed for various heights of the Cdots solution, i.e.: from 5.364 cm to 13.000 cm. Using the Tracker software, the value of the Cdots’ refraction index is 1.29 0.03, which is comparable to the refraction index of water. This measuring instrument has the potential to be used in high school physics classes and/or first-year university physics courses.

Effective waste heat recovery from industrial cohesive granular materials: A moving bed indirect heat exchanger with special flow control

Particle-based moving bed heat exchangers are increasingly playing a significant role in industrial energy conservation and solar energy utilization. However, the moving bed heat exchanger used for cohesive granular materials still needs to be developed. This paper investigates the feasibility of indirect heat transfer of cohesive granular materials through a moving bed heat exchanger. A vibrating moving bed heat exchanger is developed for the metallurgical slag of vanadium-titanium (MSVT) from industry. The experiment demonstrates that the vibrating moving bed heat exchanger can establish an approximate mass flow regime of MSVT in the experimental section. The vibration device designed for the experimental and discharge section effectively resolves bridging and the intermittent collapse of arching in cohesive granular materials. The outer side of the tube is tightly wrapped by MSVT with vibration. Significant differences are observed in the flow and heat transfer behavior of MSVT between the aligned and staggered tubes. The local heat transfer coefficient at the top and bottom of the aligned tubes exhibits much lower sensitivity to flow velocity compared to the staggered tubes. The relationship between Nu−1 and Pe−0.5 or MSVT around the aligned and staggered tubes follows a linear correlation. Compared to aligned tubes, Nu−1 for MSVT in staggered tubes shows an average reduction of 28%.

Experimental study on break and velocity characteristics of liquid column between horizontal tubes

Column flow is one major flow mode in horizontal-tube falling-film evaporator. In this study, a horizontal-tube falling-film flow experiment platform is built up. A high-speed camera is used to shoot the process of falling and break of liquid column at the bottom of horizontal tube. Image edges are detected using the algorithm based on Sobel to quantify the liquid column features. Liquid column break process, falling velocity, variation pattern of break shape and break length, as well as the special phenomenon encountered in column falling process are discussed in detail. Results show that the break of liquid column undergoes three stages. The liquid column break shape has a periodic variation pattern, and the liquid column break length fluctuates within a certain interval. In addition, as the spray increases, break length increases, and the fluctuation interval of break length expands. The liquid falls downward spirally and its velocity rises in waves with time, and there exists an obvious uniform phase. In spray density range of 0.03–0.05 kg/m⋅s, liquid column falling velocity increases and the uniform phase is delayed as the spray increases. But when spray density varies in 0.05–0.06 kg/m⋅s, no significant increase in liquid falling velocity can be found.

Extraction and preconcentration of parabens from the human follicular fluid through dispersive micro solid phase extraction using microporous MIL-68 (In) followed by in-situ effervescence-boosted dispersive liquid-liquid microextraction

For the first time in this study, a microextraction method was developed to perform follicular fluid safety assessment analysis. The drastic importance of follicular fluid safety on the proper nourishment and development of oocytes caused the development of the present method. Since women are regularly exposed to parabens through cosmetics, healthcare, and hygienic products, the infection of body fluids is probable in long-term exposures. Also, for the first time, MIL-68 (In) was applied in an analytical method. Moreover, a new method called in-situ effervescence-boosted dispersive liquid-liquid microextraction was adopted for the simultaneous derivatization and preconcentration of the target parabens. To perform the method, 25 mg of MIL-68 (In) was dispersed into the solution of follicular fluid by vortexing. Then, 1.0 mL of 2-propanol was used to elute the analytes from the absorbent via vortexing. The analyte-enriched organic phase was mixed with 100 µL of acetic anhydride (derivatization agent) and 27 µL 1,2-dibromoethane (extraction solvent) which was swiftly injected into a sodium carbonate solution. Following the centrifugation, the extraction solvent was sedimented at the bottom of a conical bottom glass test tube and an aliquot of it was injected into a gas chromatograph equipped with a flame ionization detector. Wide linear ranges (120–25000 µg L-1), satisfactory extraction recoveries (31–79%) and enrichment factors (31−79), and appreciable limits of detection (7–36 µg L-1) and quantification (25–120 µg L-1) were recorded. The high surface area of MIL-68 (In) (608.82 m2 g-1) and its significantly low average pore diameter (13.829 A°) provide an ideal platform for the extraction of parabens from the complex matrix of follicular fluid.

High-efficient co-removal of copper and zinc by modified biochar derived from tea stalk: Characteristics, adsorption behaviors, and mechanisms

Tieguanyin tea stem was used as a raw material, and potassium hydroxide (KOH), hydrochloric acid (HCl), potassium ferrate (K2FeO4), and other modifiers were used to synthesize three modified biochar (HCl-BC, KOH-BC, Fe-BCs), for competitive adsorption of copper (Cu2+) and zinc (Zn2+). Among them, Fe-BCs had the highest adsorption capacity. Fe-BC650 (K2FeO4-modified biochar heated at 650 °C) could reach adsorption equilibrium in 1 min with a high adsorption capacity. The maximum adsorption capacity of Fe-BC650 for Cu (II) and Zn (II) in the single-heavy metal solution was 303.5996 mg/g and 254.0711 mg/g, respectively. However, there were antagonistic impacts between Cu2+ and Zn2+ after analysis by the extended Langmuir model. The Brunauer-Emmett-Teller (BET) results indicated the specific surface area of Fe-BC650 was multiplied by 245 than the raw biochar (BC650), and the iron species was present in the pores of biochar through FeO bonding rather than on the surface. The results of dissolved organic carbon showed that iron species promoted the formation of aromatic structure but decreased the abundance of aromatic species in the composition. Moreover, K2FeO4 provided a large amount of K+ that could undergo cation exchange reactions with Cu2+ and Zn2+. The heavy metals became flocculent precipitate(MCO3) and deposited at the bottom of the centrifuge tube by flocculation. These characteristics constitute the excellent adsorption performance of Fe-BC650.

Intensification of aqueous mineralisation of CO2 with CaO containing industrial wastes in a modified airlift reactor

CO2 mineralisation is considered the safest storage medium for mitigating climate change. One of the challenges with the industrial demonstration of the mineralisation technology is reactor design. In the current study we demonstrate the use of draft tube based reactor for the mineralisation of CO2. The draft tube reactors show better performance as compared to the absence of draft tube at near ambient pressure for CO2 at different concentrations. The draft tube has been modified to increase the gas-liquid mass transfer rate by adding multi-orifice plates on top as well as increasing the solid precipitation in the reactor with a spiral flow arrangement at the bottom of the draft tube. At higher CO2 concentrations and near ambient pressures, the draft tube with modifications shows 2.5 fold enhancement in the overall rate as compared to draft tube without modifications. Additionally, at lower CO2 concentrations (i.e. near flue gas concentrations), the draft tube with modifications has better conversion capacity as compared to draft tube without modifications. This enhancement is due to the increased gas holdup and separation of solids in the draft tube with modifications. The precipitates obtained in the draft tube reactors show nanoparticles arranged in coral or mosaic arrangements as compared to the reactor without draft tube.

Numerical Simulation Analysis of the Full-Section Immersed Tube with the Post-Pouring Belt under Hydration Reaction

To study the force and deformation characteristics of a full-section immersed tube with post-pouring belt under the action of hydration reaction, the numerical model of full-section immersed tube with post-pouring belt was established by using MIDAS FEA (V2013) finite element analysis software, and the stress, cracking and deformation of the segment of the post-pouring belt were analyzed. The results show that under the action of hydration reaction, the concrete reaches the highest temperature at about 36 h, which appears at the roof of the tube gallery in the immersed tube, and the bottom steel plate expands rapidly initially, and subsequently shrinks gradually. The outer surface of the post-pouring segment concrete is stretched, and the internal region is under pressure, and as the internal temperature of the concrete cools down, the bottom plate starts to contract. The steel bar connection between the post-pouring belt and the surrounding immersed tube segment will increase the risk of cracking in the bottom plate of the full-section immersed tube. When only the steel bars in the bottom plate are connected, the maximum tensile stress of the immersed tube bottom plate will increase by 16.0% compared to the no connection case. If the steel bars of the immersed tube’s web and roof are also connected, the maximum tensile stress will increase by over 20%. By connecting the steel bars, the peripheral tube section plays a certain role in limiting the transverse deformation of the post-pouring belt and constraining the reinforcement of the bottom plate and web (and roof) can reduce the transverse deformation of the immersed tube to a great extent, reducing the proportion by over 10%.

THERMAL-POWER-PLANT CONDENSER-TUBE CORROSION ANALYSIS

The thermal-power-plant condenser tubes, conducting cooling seawater, experienced frequent leakages, prompting the hereby presented failure analysis. Visual inspection of the corroded/ruptured tube segments revealed that localized corrosion may be linked to seawater sediments and thick layers of corrosion products at the tube water side. Sediments were found along the tube bottom and thick corrosion products were found adjacent to the point of contact between the baffle plates and the exterior tube walls. Underdeposit corrosion, accelerated due to sulphate-reducing bacteria, was diagnosed based on the excess sulphur found at the pit bottom using EDX, the FT-IR spectrum indicating the presence of biofilm and SEM determining the featuring corrosion products based on the biofilm. It was proposed that the corrosion initiating deposits were linked to the condenser shutdown and startup periods. Results showed that pitting corrosion occurred under the influence of biofilm microorganisms tolerant to copper. The main goal of this research was achieved by defining a systematic procedure for avoiding a shutdown of the thermal power plant.

Characterization of a late bronze age “Kohl Box” from the Cilician Plain using FTIR and GC–MS

The subject of this study is a Late Bronze Age kohl box decorated with zoomorphic motifs recovered from Tepebağ Höyük (Cilician Plain, Turkey) and a quantity of black pigment that remained at the bottom of this box tubes. In ancient times, this kind of black pigments was used for the treatment of eye diseases and to reduce the brightness of the sun by applying it intensively around the eyes, rather than for its aesthetic and ornamental function. According to the spectroscopic results, the analyzed sample contains mostly lead-based minerals, which is mainly galena, a lead sulfide derivative known to be used as a kohl in ancient times. The chromatographic results indicated that there may be decomposed organic residues (ORs) in the sample, which may be from oil or fat. When the archaeological and archaeometric data are interpreted together, it is concluded that the powder compound within the sample, in accordance with the existing literature, is kohl and thus, the artifact may be a kohl box imported from Egypt.

Experimental and simulation on night heat dissipation characteristics and freezing process of evacuated tube solar water heaters

The winter operation of all-glass evacuated tube solar water heaters (ETSWH) often encounters the problem of ice damage. Studying their nighttime heat dissipation and freezing characteristics can further reduce the risk of frost damage during winter use. A numerical model for the nighttime heat dissipation of all-glass evacuated tube collectors is proposed in this study. An enthalpy equation is also introduced to analyze the heat dissipation process and freezing conditions of water inside the ETSWH under lower temperature conditions. Based on this, a nighttime heat loss model for solar vacuum tube collectors, including the effects of radiation and phase change factors, is established and validated through nighttime temperature drop experiments, which can effectively predict the temperature distribution and antifreeze performance of ETSWH during the nighttime heat dissipation process. In addition, the independent effects of the initial temperature of the water inside ETSWH, the thickness of the water tank insulation layer, and the absorptive coating emissivity on the heat dissipation process of ETSWH are studied, and the heat dissipation of ETSWH during winter nights in five different climatic zones in China is simulated. Experimental and simulation results show that under cold and clear winter weather conditions in Luoyang, ice forms in ETSWH during nighttime. The icing first occurs at the bottom of the vacuum tube, and the icing length on the wall and the icing thickness at the bottom can reach 1145 mm and 15 mm, respectively. In severely cold areas and cold regions such as Harbin and Beijing, there is a high risk of frost damage to ETSWH during winter. Keeping the initial working fluid temperature in the heater above 50 °C, ensuring a minimum insulation thickness of 50 mm, and reducing the emissivity of the absorptive coating in the heater to below 0.07 can effectively solve the freezing problem and have significant implications for the promotion and application of all-glass evacuated tube collectors.