Mm In Internal Diameter Research Articles

Determination of cocaine and its metabolites in blood by gas chromatography coupled with mass spectrometry (GC-MS)

Introduction. This article aims to present a simple and sensitive chromatographic method, carried out in the gas phase using detection by mass spectrometry to identify and quantify cocaine and its metabolites in the blood, notably Benzoylecgonine and Ecgonine Methyl ester. Methods. This method involves liquid-liquid extraction using a mixture of solvents, consisting of chloroform and isopropanol, followed by silylation. The separation was carried out using an xi-5ms column (Restek®) of 30 m in length, 0.25 mm in internal diameter and 25 μm in film thickness. Results. Blood level quantification of Benzoylecgonine and Methylester Ecgonine was possible with respective quantification limits of 18 and 39 ng/mL. The method is linear over a range of 75 to 1000 ng/mL and the extraction yields range between 81% and 97%. Regarding the intra- and inter-run precision and the accuracy of the method, the coefficients of variation and biases at the three concentration levels (150, 300 and 750 ng/mL) are well below 15%. This method can easily be applied to blood samples, both in emergency toxicology and in forensic toxicology, to confirm any previous, voluntary, or accidental intake of cocaine.

World’s largest natural gas leak from nord stream pipeline estimated at 478,000 tonnes

Methane is a potent heat trapping gas believed to account for 30% of the observed global warming to-date. At a capacity of 110 bcm/year, the Nord Stream (NS) pipeline corridor measuring 1,153mm in internal diameter and stretching 1,224km from Russia to Germany is the biggest in the world. The explosions that NS sustained in September, 2022, in the Baltic Sea, have unleashed the largest single methane gas source in recent memory. Over the course of 7days, our transient multiphase pipeline model has estimated that the gas leaks from 3 lines pumped 478,000 tonnes of methane into the atmosphere. A range of pipeline shut-in pressures as a function of leakage time deduced an envelope of gas volume that matched the timeline of observed outflows. Interestingly, the methane gas that escaped from the damaged threads amounted to the CO2 equivalent emitted by concrete sufficient to build about 27 Burj Khalifa towers.

A modified apical resection model with high accuracy and reproducibility in neonatal mouse and rat hearts

Neonatal mouse heart can regenerate after left ventricle (LV) apical resection (AR). Since current AR rodent method is accomplished by resecting LV apex until exposure of LV chamber, it is relatively difficult to operate reproducibly. We aimed to develop a modified AR method with high accuracy and reproducibility and to investigate whether cardiac regenerative capacity could be replicated in neonatal rats. For 15% AR of whole heart weight in 1-day-old (P1) neonatal mice, a modified 10 μL pipette tip cut to 0.48 mm in internal diameter was connected to a vacuum pump working at 0.06 ± 0.005 MPa and gently kept in touch with LV apex for nearly but no more than 12 s. LV apex was resected by a single incision adjacent to the pipette tip. The modified AR method in P1 mice achieved cardiac structural and functional recovery at 21 days post resection (dpr). Data from different operators showed smaller variation of resected LV apex and higher reproducibility using the modified AR method. Furthermore, we showed that 5% AR of whole heart weight in P1 neonatal rats using a modified 200 μL pipette tip cut to 0.63 mm in internal diameter led to complete regeneration of LV apex and full preservation of cardiac function at 42 dpr. In conclusion, the modified AR rodent model leads to accurate resection of LV apex with high homogeneity and reproducibility and it is practically convenient for the study of structural, functional, and molecular mechanisms of cardiac regeneration in both neonatal mice and rats.

Associação de adesivos universais com silanos na adesão em blocos de CAD/CAM

ABSTRACT Objective: This study assessed whether the use of a silane coupling agent influence the bond strength of two universal adhesives to ceramic or resin CAD/CAM blocks. Methods: Forty-eight samples were obtained from each resin nano-ceramic hybrid block (RCBs) and lithium disilicate ceramic blocks (LD). Samples were treated with silane with MDP (Monobond - S-MDP), silane without MDP (Prosil - PS), and no silane application (Control - Ctr) followed by universal adhesive with silane (UAS) and without silane (UA) (n=8). Three polyurethane tubes (1.5 mm of internal diameter) were positioned in each sample treated surface and filled with a dual cured resin cement. Bond strength was assessed by microshear bond strength test and failure analysis was performed for all samples. Results: For the RCBs, UAS presented the highest bond strength values (p=0.004). Silane application was not significant in bond strength values (p=0.444). For LD, silane application was significant in bond strength values (p<0.001), but the adhesive was not (p=0.066). Failure analysis showed high prevalence of adhesive failures for both substrates. Conclusion: A silane-containing universal adhesive promoted the best bond strength results to the resin nano-ceramic hybrid block. For bonding to a glass-ceramic CAD/CAM material, additional silane (without MDP) application presented the best results.

Experimental Study of an upflow Fluidized Bed: Identification of Fluidization Regimes

The concept of solar receiver using fluidized particles as heat transfer fluid is attractive from the point of view of its performance but also of the material used. In this concept, the receiver is composed of tubes subjected to concentrated solar radiation in which the fluidized particles circulate vertically. Circulation in the tubes, immersed in a “nurse” fluidized bed, is ensured thanks to a controlled pressure difference imposed on the latter and secondary aeration. This ventilation located at the bottom of the absorber tubes makes it possible to control the fluidization regimes. The latter strongly influence the parietal heat transfers and therefore the performance of the receiver. In order to better understand the conditions of appearance of these regimes and to better identify them, a study at room temperature was carried out with a tube 45 mm in internal diameter and 3.63 m in height. The tube is instrumented with several pressure sensors distributed over its height. More than 170 experiments have been performed exploring wide ranges of particle and aeration flow rates, with and without particle circulation. Signal processing methods, classically used in the scientific literature of fluidized beds, are applied. Combined together, these methods have enabled the identification of bubbling, pistoning (of the wall and axisymmetric), turbulent fluidization and rapid fluidization regimes. The pooling of all this information allows the establishment of a diagram of the fluidization regimes and their transition, showing that the local slip velocity is the key parameter governing the structure of the flow.

Production of Nanocarbon from Local Raw Materials

This research aims at extraction of nanocarbon from local raw materials through a detailed study of its characteristics. The research involves study of thermal properties of fruit kernels (apricots) and walnut kernels, determining the optimal modes of the carbonization process for each type of raw material, developing a method for the synthesis of spherical granules by liquid granulation and determining the optimum concentration of the sulfuric acid solution used in granulation. Analysis of the results on the dynamic sorption of petroleum products showed that maximum sorption is achieved when using a sorbent obtained at 400∘C for 30 minutes. Temperature regimes have been optimized for obtaining sorbent from walnut shells with different carbon content. The hydrophobicity and oleophilic of their surface are common to all these materials. The dynamic conditions of the adsorption capacity processes under the sorbents were studied. Sorption efficiency and the specific capacity of sorbents were determined. It has been shown that the technological cycle of the studied sorbents can be repeated by repeated purification. When activated charcoal is used to purify water from petroleum products, the process of leaching with colloidal and finely dispersed mixtures – it was found that deaeration is necessary. The individual composition of the ether fraction OV-1 has a fixed liquid phase, Connected to Finuigan 4023 Automated GC/MS System mass spectrometer, It was determined by chromato-mass spectrometry in a capillary column 40 m long and 0.25 mm in internal diameter. The results of the Fure-IR spectroscopy study of samples based on the apricot peel, walnut peel, and walnut peel showed that winning symmetrical bands (2920 and 2851 cm−1) were observed in them, these bands belong to the C-H-valence oscillation belonging to the methyl and methylene groups. In the spectrum taken from a sample of apricot peel, absorption bands belonging to cellulose (1377 cm−1 and 1069 cm−1 ) were observed.
 Thermogravimetric studies were performed on an STA 449C Jupiter synchronous thermal analysis instrument in the inert environment at a heating rate of 10∘ C/min in the temperature range of 25–1000∘C. Analysis of the porous structure parameters of carbon sorbents were carried out using the high-speed analyzer of gas sorption NOVA-1200e by the method of imaging nitrogen adsorption isotherms at a temperature of 77K.

Performance analysis of a solar parabolic trough collector fitted with a helical coiled tube absorber

The SPTC is used for medium- and high-temperature applications. Several works are carried out for the enhancement of heat transfer of SPTC using size variation, absorber with inserts, nanofluid with working medium and different configurations of the absorber. The development of turbulence effect in the working fluid is important for heat transfer enhancement. Therefore, a novel idea is introduced to use a helical coiled tube absorber in the PTC, which enhances the heat transfer between the tube and the flowing fluid by providing swirling motion. The current research work uses the helical coiled tube absorber which consists of 42 turns and 2 m in length, 10 mm in internal diameter and 12.5 mm in outer diameter. It is enclosed by a glass envelope to reduce thermal losses. The experiments are conducted by varying the mass flow rate of water from 0.01 kg s−1 to –0.03 kg s−1. The maximum achieved useful heat gain, water temperature and instantaneous efficiency are 800 W, 64°C and 56%, respectively while using the flow rate of 0.01 kg s−1.

An Airway-Centric View of Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is the cumulative manifestation of countless, spatially and temporally distinct, microscopic foci of maladaptive repair in response to recurrent lung injury. However, the key drivers, essential cells, and critical mechanisms of maladaptive repair in IPF remain elusive. Decades of research have focused on alveolar injury and alveolar-mesenchymal crosstalk with their association to type II alveolar epithelial defects, fibroblast activation, and progressive lung fibrosis resulting in diminished organ function. Additionally, it has been well documented that immune and endothelial cell-types are involved in IPF. However, the airway epithelium has been incompletely described in IPF, even with significant evidence of airway-specific involvement. One of the first descriptions of distal airway dysfunction in IPF was over four-decades ago; however, since this discovery, our understanding of distal airway epithelial contributions to IPF pathogenesis has not kept pace with other tissues-types or anatomical regions of the lung. Healthy distal, which is defined here as an airway < 2 mm in internal diameter, airway epithelium is composed primarily of progenitor, mucus-producing, and multiciliated cell populations. Large increases in progenitor population diversity, misexpression of mucus, and possible aberrant ciliation observed in IPF has reinvigorated interest in the distal airway epithelium.

Nesting biology of Pareumenes quadrispinosus (de Saussure, 1855) (Hymenoptera: Vespidae: Eumeninae) in trap nests in North Vietnam

• Pareumenes quadrispinosus is a common species using trap nests in North Vietnam. • The nests are built from mid-April to last October. • The number of provisioned cells in a nest is one to four. • Brood cells were provisioned with caterpillars. • It is multivoltine, with two alternative life histories and overlapping generations. Nests of Pareumenes quadrispinosus (de Saussure, 1855) were obtained at Me Linh Station for Biodiversity (323 nests) and Tam Dao Town (283 nests), Vinh Phuc Province, as well as at Phu Luong, Thai Nguyen Province (9 nests) and Kim Boi, Hoa Binh Province (62 nests). The wasps nested in segments of bamboo canes and reed stems, 5 to 18 mm in internal diameter. Each nest consisted of a linear series of one to four cells, separated by mud partitions. Brood cells were provisioned with caterpillars and eggs were attached to the ceiling of the cells by thin threads. The life history and sex ratio of this species nesting in trap nests in North Vietnam were recorded from mid-April to last October. The species is multivoltine, with likely up to four generations per year. It has two alternative life histories (diapause and direct development) and overlapping generations. The sex ratio is strongly female-biased. Only 46% of the provisioned cells were successful; the others were damaged by nine parasitoid species or died during development for unknown reasons.

Numerical analysis of flow patterns maps in horizontal pipes with variation of inclination angles in a collector/evaporator of a DX-SAHP

This research describes the flow pattern maps of R600a that were generated in a horizontal pipe with different inclination angles in a collector/evaporator of a DX-SAHP. The solar flat-plate collector dimensions were 3.8 and 1000 mm of internal diameter and length, respectively. The influences of mass velocities, heat flux and inclination angles were analyzed. Five experimental tests were carried out with inclination angles between 10 and 45°, mass velocities between 203.24 and 222.28 kg·m−2·s−1, solar heat flux values of 200.58 and 507.23 W·m−2 were used. The numerical analysis was carried out based on the correlations proposed by Kattan and Kundu, in addition, a flow pattern map for horizontal pipes without inclination is shown, under Wojtan's mathematical model, thus indicating the difference when working with pipes in similar conditions by varying their inclination in capture to incident solar radiation. Results obtained present flow pattern maps where six zones can be seen: intermittent, annular, mist, slug, stratified, wavy stratified.

Long-acting muscarinic antagonists and small airways in asthma: Which link?

Involvement of small airways, those of <2mm in internal diameter, is present in all stages of asthma and contributes substantially to its pathophysiologic expression. Therefore, small airways are a potential target to achieve optimal asthma control. Airway tone, which is increased in asthma, is mainly controlled by the vagus nerve that releases acetylcholine (ACh) and activates muscarinic ACh receptors (mAChRs) post-synaptically on airway smooth muscle (ASM). In small airways, M3 mAChRs are expressed, but there is no vagal innervation. Non-neuronal ACh released from the epithelial cells that may express choline acetyltransferase in response to inflammatory stimuli, as well as from other structural cells in the airways, including fibroblasts and mast cells, can activate mAChRs. By antagonizing M3 mAChR, the contraction of the ASM is prevented and, potentially, local inflammation can be reduced and the progression of remodeling may be averted. In fact, ACh also contributes to inflammation and remodeling of the airways and regulates the growth of ASM. Several experimental studies have demonstrated the potential benefit derived from the use of mAChR antagonists, mainly long-acting mAChR antagonists (LAMAs), on small airways in asthma. However, there are several confounding factors that may cause a wrong estimation of the relationship between LAMAs and small airways in asthma. Further studies are needed to differentiate broncholytic and anti-inflammatory effects of LAMAs and to better understand the interaction between LAMAs and corticosteroids, also in the context of a triple therapy that includes a β2 -AR agonist, at different levels of the bronchial tree.

Construction of polymer monolithic columns in polypropylene ink-pen tubes for separation of proteins by cation-exchange chromatography.

We describe the synthesis of polymer monoliths inside polypropylene tubes from ink pens. These tubes are cheap, chemically stable, and resistant to pressure. UV-initiated grafting with 5wt% benzophenone in methanol for 20min activated the internal surface, thus enabling the covalent binding of ethylene glycol dimethacrylate, also via photografting. The pendant vinyl groups attached a poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) monolith prepared via photopolymerization. These tubes measured 100-110mm long, with 2mm of internal diameter. The parent monoliths were functionalized with Na2 SO3 or iminodiacetate to produce strong and weak cation exchangers, respectively. The columns exhibited permeabilities varying from 2.7 to 3.3 × 10-13 m2 , which enabled the separation of proteins at 500 µL/min and back pressures<2.8MPa. Neither structure collapse nor monolith detachment occurred at flow rates as high as 2.0mL/min, which produced back pressures between 6.9 and 9.0MPa. The retention times of ovalbumin, ribonuclease A, cytochrome C, and lysozyme in salt gradient at pH 7.0 followed the order of increasing isoelectric points, confirming the cation exchange mechanism. Separation and determination of lysozyme in egg white proved the applicability of the columns to the analysis of complex samples.

Pressure Loss on Corrugated Annulus of Double Pipe Heat Exchanger

Fluid flow performances were performed as preliminary research on double pipe heat exchanger with longitudinally corrugated. In this experiment, the annulus tube is geometrically design and form of alternating groove. This experiment using longitudinal grooved pipe as inner tube of double pipe heat exchanger. The objective of this investigation is to determine the pressure loss along the pipe as a time series function. The fluid mechanics analysis of in this paper also provide pressure drop of system and presenting pressure signal. The longitudinal grooves were incised on outer surface of tube side with number of longitudinal grooves of 2. 0.3 mm high and 1 mm width grooves were kept constant. The tube made of aluminium with outer diameter is 20 mm. The shell is made of acrylic which has 26 mm in internal diameter. The hot fluid flows in tube space and the cold fluid flows in the annulus space of double pipe heat exchanger. Counter flow scheme use in this experiment with water as working fluid. The volume flowrate of cold fluid was varied from 11 lpm up to 15 lpm which is equal to Reynold Number (Re) range around 31981 up to 43610. The other hand, the volume flowrate of hot fluid remains constant at 15 lpm which is equal to (Re) around 30904. Pressure data was recorded using differential pressure tranducers and digitalize using data logger. The corresponding comparison of the pressure drops revealed the corrugated double-pipe heat exchangers had 5.2 % larger pressure drop. The grooved-double pipe heat exchanger has more disadvantage on fluid performance since the thin corrugated area are slightly increased which essentially correlation on larger pressure drop.

Comparison of Two Gas Injection Methods for Generating Bubbles in a T-junction

In this work, we compare the performance of two different methods for generating bubbles in conditions relevant to microgravity. A T-junction formed by two cylindrical (1 mm of internal diameter) and perpendicular channels is used to generate trains of non-wetting bubbles. Air and distilled water are used as dispersed and continuous phases, respectively. The difference between both methods lies in the strategy used to inject the fluids. In one case (here referred to as TJ-A configuration), the gas is injected into the side channel. In the other case (referred to as TJ-B), the gas is injected into the main channel. Bubble size dispersion is analyzed and quantified with the polydispersity index. The increase of the capillary number (based on the continuous phase) has shown a strong influence on the regularity of the bubble generation process. The TJ-A method can produce monodisperse bubbles at higher capillary numbers than configuration TJ-B. The limits of monodispersity, as far as the capillary number is concerned, are studied. These limits determine the optimal operating range of the T-junction for generating highly monodisperse bubbles. Beyond these limits, polydispersity increases, although much more abruptly in TJ-B than in TJ-A. The bubble generation frequency is also studied, with special attention to the two main regimes that characterize the frequency, i.e. the linear regime (at very low gas flow rate) and the saturation regime (at high gas flow rates). A new dimensionless expression of the bubble generation frequency is proposed in this work.

Numerical and Experimental Study of the Squeezing-to-Dripping Transition in a T-Junction

In this work, we study the transition from squeezing to dripping during the formation of bubbles in a capillary T-junction in conditions relevant to microgravity. The junction is formed by two perpendicular cylinders of equal section (1mm of internal diameter). The capillary number Ca (based on the continuous phase) is used as the key parameter of the study. For the range of Ca covered in this paper, the same two common bubble formation mechanisms as the ones described in the related literature have been observed: squeezing regime at low Ca and dripping regime for higher Ca. This paper provides a new value of the critical Ca for the transition from squeezing to dripping. This value has been obtained with two independent approaches, experimentally and numerically. Experimental photographs have been used to determine the value of Ca at which a gap appears between the forming bubble and the capillary’s wall, as an evidence of the activation of the shearing mechanism related to the dripping regime. Additionally, the dependence of the bubble volume on the capillary number and the gas/liquid flow rate ratio has been analysed. In this work, we also propose a new numerical approach, complementary to the experimental one, carried out with the Computational Fluid Dynamics solver ANSYS Fluent v15.0.7. Numerical simulations have been performed to study the geometry and the behaviour of the gas-liquid interface during the cycle of bubble formation. Upstream the T-junction, as the fluctuation in pressure decreases, the vertical movement of the rear meniscus (gas-liquid interface in contact with the solid vertical capillary) also decreases, and the shear stresses begins to play an active role until overcoming the squeezing mechanism. Numerical simulations presented in this paper support the experimental observations, confirming that Computational Fluid Dynamics studies can be a useful tool to improve the experimental knowledge.

NEXThaler® – inovatyvus sausųjų miltelių, ypač smulkias vaisto daleles formuojantis fiksuotų dozių beklometazono ir formoterolio inhaliatorius, skirtas smulkiųjų kvėpavimo takų gydymui sergant astma

Naujausių tyrimų duomenimis, smulkiųjų kvėpavimo takų pokyčiai, sergant astma, yra gana dažni ir gali būti randami netgi tiems pacientams, kuriems nėra proksimalinių bronchų obstrukcijos požymių. Periferiniai, labiausiai nutolę kvėpavimo takai, paprastai vadinami smulkiaisiais bronchais ir jų vidinis skersmuo yra &lt;2 mm, o tai sukelia didžiąją oro srauto pasipriešinimo dalį sergant astma. Paprastai į kvėpavimo takus įkvepiamos dalelės turi būti mažesnės nei 5 μm. Tačiau tik gerokai mažesnį vidutinį aerodinaminį skersmenį (MMAD) turinčios dalelės gali veiksmingai patekti į smulkiuosius kvėpavimo takus ir juose nusėsti. Įrodyta, kad inhaliatorius yra labai svarbus veiksnys, užtikrinantis, kad inhaliuojamasis vaistas pasiektų netgi tolimiausias bronchų medžio dalis bei taip pagerintų astmos gydymo rezultatus ir simptomų kontrolę. NEXThaler® sausųjų miltelių inhaliatorius (DPI) buvo sukurtas specialiai atsižvelgiant į astma sergančių ir kasdien įkvepiamuosius vaistus vartojančių pacientų poreikius. Gydant NEXThaler® DPI, vaistai patenka tiek į stambiuosius, tiek į smulkiuosius kvėpavimo takus. Atliktų tyrimų duomenimis, NEXThaler® DPI: 1) patogus naudoti kiekvieną dieną, nes lengvai paruošiamas: „atidarai – įkvepi – uždarai“; 2) triguba grįžtamojo ryšio sistema, susieta su prietaiso aktyvinimu, tik esant pakankamai įkvėpimo srovei, o tai užtikrina, kad pacientas įkvėps visą reikalingą vaisto dozę kiekvienos inhaliacijos metu; 3) prietaiso generuojamos ypač smulkiosios vaisto dalelės veiksmingai pasiekia ir smulkiuosius kvėpavimo takus.

The effect of mode of inhaled salbutamol delivery on measures of small airways obstruction in asthma: a comparison of treatment delivered via spacer and nebuliser

Background Conventional clinical respiratory tests tell us little about the small airways of the lung (less than 2 mm in internal diameter). Patients with asthma affecting the small airways may respond differently to inhaled bronchodilator treatment (salbutamol) depending on the method of administration. Aims In this study, we aimed to assess if there was a difference in the effect of salbutamol treatment via metered-dose inhaler (MDI) and spacer compared to via nebuliser on measures of small airways function. It was hypothesised that the nebulised salbutamol would have a greater effect on the outcome measures due to the particle size being more appropriate for penetrating the smaller airways. Methods Two visits were completed by 14 participants with stable asthma. At both visits, lung function tests were completed both before and after administration of 1 mg salbutamol to measure airway obstruction (spirometry), mechanical load to ventilation (impulse oscillometry), and ventilation heterogeneity (multiple breath nitrogen washout). At visit one, seven participants were randomized to take salbutamol via MDI and spacer, and seven via nebuliser. At visit two, all participants took salbutamol via whichever method they had not been given at visit one. Results Results indicated that participants given salbutamol via MDI and spacer (compared to via nebuliser) showed a greater improvement, which was statistically significant, between the pre- and post-salbutamol values for most lung function tests. Discussion This result was unexpected and may have been due to greater wastage of drug via nebuliser than via MDI and spacer, and differing inhalation patterns. Tidal breathing during nebulised administration, and deep inhalation during use of MDI and spacer, could have affected the delivery of the drug. Conclusion This study implies that taking salbutamol via MDI and spacer would be beneficial if higher doses (e.g. 1 mg) were taken.

Performance assessment on double pipe heat exchanger with longitudinal groove

Thermal performances were performed as preliminary research on double pipe heat exchanger with low number of longitudinal groove. The objective of this work is to determine optimal heat transfer parameter especially logarithmic temperature difference (LMTD) as a time series function. The thermal analysis in this paper also provide total number of heat absorb in the cold fluid. The rectangular-longitudinal grooves were incised on outer surface of tube side with number of longitudinal grooves of 2. The grooves high and width were kept constant at 0.3 mm and 1 mm respectively. The tube made of aluminium with outer diameter is 20 mm. The shell is made of acrylic which has 26 mm in internal diameter. Water is used as the working fluid with counter flow scheme. The volume flowrate of cold fluid was varied from 18x10^-5 m^ 3/s up to 25x10^-5 m^ 3/s which are equal to Reynold number (Re) around 31981 to 43610. The volume flowrate of hot fluid remains constant at 25x10^-5 m^ 3/s which is equal to (Re) around 30904. The LMTD of 2 grooves double pipe heat exchanger was better compared to that of the smooth one since the thermal sectional area are increased which essentially cause larger heat transfer.

Efficacy of eucalyptus oil (Eucalyptus globulus), sweet orange oil (Citrus sinensis), and grapefruit oil (Citrus paradisi) as bioceramic sealer solvents

Background: Essential oil–based gutta-percha solvents have been extensively studied due to their nontoxicity and effectiveness compared to conventional solvents. These solvents can also be used to remove different types of endodontic sealers. Bioceramic-based sealers have become increasingly popular; however, they are difficult to dissolve. Objective: The aim is to examine the differences in efficacy between eucalyptus oil (Eucalyptus globulus), sweet orange oil (Citrus sinensis), and grapefruit oil (Citrus paradisi) as bioceramic sealer solvents. Methods: Thirty-two bioceramic sealer samples were placed in cylindrical stainless steel molds 1.5 mm in height and 8 mm in internal diameter and were placed in an incubator to set. After 72 h, the sealer samples were weighed to obtain their initial weights. Then, they were divided into three groups of ten, which were immersed in 1 ml of eucalyptus, sweet orange, or grapefruit oil for 1 min, and one group of two, used as negative controls. The sealer samples were placed in an incubator for 24 h to dry and weighed once more to obtain their final weights. The differences in weight were calculated and analyzed using one-way analysis of variance. Results: The analysis of the initial and final weight differences of the sealer samples immersed in the three essential oils revealed no statistically significant differences between them. Conclusions: The three essential oils have comparable efficacies as bioceramic sealer solvents.

The seepage transport of heavy metal Pb2+ through sand column in the presence of silicon powders

Abstract The coupled transport of heavy metals with suspended particles has been a topic of growing interest. The main purpose of this study is to experimentally investigate the seepage transport of heavy metal Pb2+ in the presence of silicon powders (SPs) through a sand column under different seepage velocities (v = 0.087–0.260 cm/s), injection Pb2+ concentrations (C P = 0–800 μg/ml) and SP sizes (D 50 = 2.8–25.5 μm), which were likely to be encountered in practical engineering. The sand column was installed in a cylindrical chamber of 300 mm in length and 80 mm in internal diameter. The results clearly show that the increase in acidity results in a reduction of the repulsive interactions between SPs and the matrix, and consequently a decrease in the peak values in breakthrough curves (BTCs), especially for larger-sized SPs. The peak values and recovery rate of Pb2+ are obviously increased and an earlier breakthrough can be observed, due to the higher capacity of SPs with negative charge to adsorb heavy metal pollutants such as Pb2+ with positive charge. The adsorption of Pb2+ on SPs can reduce the repulsive forces between SPs and the matrix, thus resulting in the increase of the deposition possibility of SPs and the decrease of peak value and recovery rate.