Absorption Rate Coefficient Research Articles

Population pharmacokinetics of Amisulpride in Chinese patients with schizophrenia with external validation: the impact of renal function.

Introduction: Amisulpride is primarily eliminated via the kidneys. Given the clear influence of renal clearance on plasma concentration, we aimed to explicitly examine the impact of renal function on amisulpride pharmacokinetics (PK) via population PK modelling and Monte Carlo simulations. Method: Plasma concentrations from 921 patients (776 in development and 145 in validation) were utilized. Results: Amisulpride PK could be described by a one-compartment model with linear elimination where estimated glomerular filtration rate, eGFR, had a significant influence on clearance. All PK parameters (estimate, RSE%) were precisely estimated: apparent volume of distribution (645L, 18%), apparent clearance (60.5L/h, 2%), absorption rate constant (0.106h-1, 12%) and coefficient of renal function on clearance (0.817, 10%). No other significant covariate was found. The predictive performance of the model was externally validated. Covariate analysis showed an inverse relationship between eGFR and exposure, where subjects with eGFR= 30mL/min/1.73m2 had more than 2-fold increase in AUC, trough and peak concentration. Simulation results further illustrated that, given a dose of 800mg, plasma concentrations of all patients with renal impairment would exceed 640ng/mL. Discussion: Our work demonstrated the importance of renal function in amisulpride dose adjustment and provided a quantitative framework to guide individualized dosing for Chinese patients with schizophrenia.

Optimization Study of CO2 Gas Absorption with NaOH Absorbent Continuous System in Raschig Ring Packing Column Using Box–Behnken Design

Increasing CO2 gas emissions results in climate change by increasing air temperature and worsening environmental problems. It is necessary to control CO2 gas in the air to overcome this. This research aims to optimize the absorption of CO2 gas in the air with 0.1 M NaOH absorbent in the column of the Raschig ring stuffing material using the response surface methodology (RSM). This research was conducted using a continuous system of three independent variables by varying the contact time (10–80 min), the flow rate of NaOH absorbent (2–5 L/min), and the flow rate of CO2 gas (1–5 L/min). The response variables in this study were the absorption rate (L/min) and mass transfer coefficient, while the air flow rate was constant at 20 L/min. Air and CO2 gas mix before absorption occurs and flow into the Raschig ring packing column so that contact occurs with the NaOH absorbent. Mass transfer of CO2 gas occurs into the NaOH absorbent, resulting in absorption. The results showed that the effect of contact time (min), the flow rate of NaOH absorbent (L/min), and CO2 gas flow rate individually and the interaction on CO2 absorption rate and mass transfer coefficient were very significant at a p-value of 0.05. Chemical absorption of CO2 also occurred due to the reaction between CO2 and OH- to form CO32− and HCO3−, so the pH decreased, and the reaction was a function of pH. Optimization using Design Expert 13 RSM Box–Behnken Design (BBD) yielded optimal conditions at an absorption time of 80 min, NaOH absorbent flow rate of 5 L/min, CO2 gas flow rate of 5 L/min, absorption rate of CO2 gas of 3.97 L/min, and CO2 gas mass transfer coefficient of 1.443 mol/min m2 atm, with the desirability of 0.999 (≈100%).

Differential method for determining the specific absorption rate coefficient of electromagnetic energy for a liquid phantom

The wide use of small-sized wearable electronic devices in various practical human activities makes it relevant to measure the proportion of electromagnetic energy absorbed by the human body. One of the most important parameters that determines it is the specific absorption rate. In this article we propose a method for determining this coefficient for a liquid phantom, with the use of computer simulation and experimental measurement of the microstrip patch antenna parameters.The antenna is located on an elliptical cylinder and operates in the medical body area network. The method is based on measuring the rise in temperature of the liquid phantom exposed to electromagnetic waves generated by a microstrip antenna over a given time. Homogeneous liquid phantom was created by changing the percentage of salt and sugar in 250 g of water, skin phantom – by changing the percentage of water in 200 g of glycerol. The proposed specific absorption rate measurement method eliminates the need to purchase an expensive set of dielectric probes, which demonstrates its cost-effectiveness. The obtained results of experimental measurements are in good agreement with the results of the performed computer simulation.

The radiative processes involving ion-atom alkali systems: The case of hydrogen and potassium

The importance of the symmetric as well as non-symmetric ion-atom absorption processes in broad spectral region within a model of solar photosphere and also within the corresponding sunspot models, has been previously emphasized. This motivated us to study the photo-association, charge-exchange and photo-dissociation absorption processes in the cases of non-symmetric and symmetric systems involving hydrogen and potassium atoms, ions, molecules and molecular-ions. We have calculated the data for molecules and molecular state characterizations needed for current computation. We determined the partial and average cross-sections and corresponding spectral absorption rate coefficients, as the functions of wavelengths, and temperatures (100 nm ⩽λ⩽1000 nm, 400 K ⩽T⩽10 000 K). Our calculations are performed for conditions that exist in different layers of weakly ionized stellar atmospheres. The obtained data are potentially of high impact and may have broad further applications, e.g., for modelling of laboratory plasmas and various astrophysical objects including geocosmical ones.

CO2 absorption performance of ChCl-MEA deep eutectic solvent in microchannel

Deep eutectic solvent (DES) has been a new type of absorbent for CO2 capture due to the advantages of environmental friendliness, simple synthesis and excellent selectivity. A series of choline chloride (ChCl)-monoethanolamine (MEA) deep eutectic solvents with various water contents were prepared. The effects of gas-liquid flow rate, molar ratio of ChCl-MEA, water content and temperature on CO2 absorption performance and mass transfer were investigated. The addition of an appropriate amount of water can effectively reduce the viscosity of DES and improve its CO2 capture ability. The results show that the CO2 absorption efficiency, absorption rate, loading and mass transfer coefficient of ChCl-MEA deep eutectic solvent are optimal when the water content is 70 wt% for the DES with the molar ratio of ChCl and MEA 1:6. When the water content exceeds 70 wt%, the hydrogen bond network of DES would be destroyed, and its CO2 capture ability would be weakened. According to the Arrhenius equation, the reaction activation energy of CO2 absorption is as low as 7.54 kJ·mol−1 when the water content is 70 wt% in DES with the molar ratio of ChCl and MEA 1:6. This study can provide technical support for the application of deep eutectic solvents in CO2 capture.

Investigation on water vapor adsorption performance of carbon based composite adsorption material ACF-silica sol-LiCl

The composite adsorption material ACF-silica sol-LiCl (ASL) is prepared by impregnating activated carbon fiber (ACF) with silica sol and LiCl to improve the water vapor adsorption performance. The silica sol provides support to the soft ACF and solidifies it. The silica sol also increases the adhesion area in the ACF for the LiCl. The LiCl can effectively improve the water vapor adsorption performance of the ACF. The adsorption performance of the ASL is optimum when the LiCl impregnation concentration is 430 mg/L. Scanning electron microscope images show that the silica sol and LiCl fill the fibers pores and spaces between the fibers in the ACF after impregnation. And adsorption kinetics of the ASL is characterized using a linear driving force (LDF) model and experiments. Results show that ASL has a high dynamic water absorption rate and adsorption rate coefficient (k). The k of the ASL reaches 1.58 × 10−4−2.05 × 10−4, which is 0.27 × 10−4−0.59 × 10−4 higher than that of the ACF. Meanwhile, the results of water vapor isothermal adsorption tests show that the impregnation of silica sol and LiCl increases the hydrophilicity of the ACF, and thus greatly enhances its water vapor adsorption capacity. The adsorption capacity of the ACF is almost 0 at P/P0 < 0.2 and reaches a maximum of 0.5479 g/g at P/P0 = 0.65. The adsorption capacity of the ASL steadily increases with the relative pressure. When the relative pressure is close to 1, the adsorption capacity of the ASL reaches 2.2876 g/g, which is 2.67 times the maximum for the ACF.

Absorption caused by potassium molecules in astrophysical plasmas: Data needed for modeling

In this study, the processes of photo-dissociation in the cases of symmetric and strongly non-symmetric systems which involve hydrogen and potassium are investigated. The aim of this study was to calculate data for those small molecules and molecular state characterizations as well as to obtain the corresponding partial and average cross-sections. Moreover, the corresponding spectral absorption rate coefficients for symmetric and strongly non-symmetric cases i.e. for K2+ and KH+ cases are given in tables as a function of temperatures and wavelengths allowing potential modeling. The current research and presented results can be of interest for astrophysical plasma research and laboratory plasma investigation.

Impact of the agarose ferrogel fine structure on magnetic heating efficiency

Magnetic nanoparticles-mediated hyperthermia was widely studied in the last decades as applicable in cancer therapy. The majority of magnetic hyperthermia research was devoted to improvement of heating efficiency by application of various nanomaterials. The influence of biocompatibility, magnetic properties, sizes, composition, and concentration of magnetic nanoparticles (MNPs) on hyperthermia efficiency was extensively studied. Also, the limits preserving biological safety and the chemical stability of MNPs delivered to the tissue were established. However, much less research concerned the impact of the physical interactions between the closest MNPs on the hyperthermia efficiency. Our goal was to demonstrate the relationships between the internal structure of soft tissue containing MNPs, and the thermal effects of an alternating magnetic field. Because agarose-based gel exhibits a tissue-like internal structure, we performed hyperthermia experiments in two types of such gel containing bare and polyethylene glycol-coated Fe3O4 nanoparticles. We described the structural difference and we estimated the ferrogels specific absorption rate coefficients (SAR) from calorimetric experiments. Magnetic measurements showed 11% lower magnetic saturation of PEG-coated MNPs than of the bare MNPs. While the SAR of ferrogel with PEG-coated MNPs was 15% greater than bare MNPs. The structural characteristics calculated from TEM and SEM images were significantly different. Particularly, we observed the nanoparticle agglomeration in the gel with bare MNPs. The bare MNPs uniformly packed and located inside agarose double helices were observed for the first time. The distribution of MNPs and their spatial configuration in gel influenced strongly the strength of bonds blocking the movement of MNPs and determined the ferrogels heating efficiency. As the tissues to which we delivered MNPs were composed of agarose gel-like structures, our results may be useful in further research on hyperthermia in vivo.

Application of Ion‐Doped Y3Fe5O12 Nanoparticles for Self‐Controlled Magnetic Hyperthermia

Herein, doped yttrium garnet (YIG) nanoparticles (NPs) ( Al, Ga, Sc are nonmagnetic ions) are studied, appropriate for self‐controlled magnetic hyperthermia (SCMH) for in vivo and in vitro applications. A microscopic model (modified Heisenberg Hamiltonian) and the Green's function technique are used to investigate the temperature, doping, and size dependence of magnetic phase transition, saturation magnetization, the coercivity, and the specific absorption rate coefficient to fulfill the conditions for magnetic hyperthermia. A set of mixed yttrium garnet magnetic NPs is found, which are suitable for applications in medicine for cancer therapy. There are two Sc‐doped YIG NPs which are the best candidates for SCMH with x = 1.08, d = 27.5 nm, and = 13.52 as well as x = 1.10, d = 29.7 nm, and = 15.44 for which the conditions for biocompatibility and maximization of are fulfilled simultaneously. Moreover, also Al‐ and Ga‐doped YIG NPs are found that can be applied for magnetic hyperthermia but with smaller effectivity.

CFD modelling of the ammonia vapour absorption in a tubular bubble absorber with NH3/LiNO3

The absorber is a key component of absorption cooling systems, and its further development is essential to reduce the size and costs and facilitate the diffusion of absorption cooling systems. Computational fluid dynamics (CFD) can facilitate the characterization of the equipment used in absorption cooling systems at lower costs and complexity, but they must be properly developed and validated to provide reliability.This study provides a detailed description and assessment of a 3D CFD bubble absorber model developed to simulate the absorption process in a vertical double pipe with the NH3/LiNO3 solution. It includes a comprehensive methodology to develop the CFD model and its validation considering the effect of the solution flow and the cooling water temperature on absorber performance parameters such as the absorption mass flux and the solution heat transfer coefficient. The results show that the ‘Volume of Fluid model’ and the ‘Realizable k-epsilon model’ provide the lowest residuals and computational times in the simulations while a good correspondence between the CFD model and the experimental data with errors below 10% and 7% for the absorption mass flux and solution heat transfer coefficient, respectively, was obtained. The maximum absorption rate and heat transfer coefficient were 0.00441 kg m−2 s−1 and 786 W m−2 K−1, respectively.

Characteristics of HFC-134a absorption rate with [Bmim][Tf2N] in falling film type absorber

To develop an absorption heat pump with a hydrofluorocarbon refrigerant, this study evaluated its absorption rate with a falling liquid film type absorber. The HFC-134a refrigerant and [Bmim][Tf2N] ionic liquid were selected as the absorbent pair. The experimental apparatus was designed using the volumetric method, and the effects of the absorbent mass flow, temperature, and pressure conditions on the absorption rate were evaluated. Additionally, we calculated the absorption rate coefficient using the HFC-134a absorption transport model. The experimental results revealed that the absorption rate affected the desired amount of absorption equilibrium under the given temperature and pressure conditions. The absorption rate increased, while the amount of absorption at the set temperature and pressure decreased. Additionally, the outlet amount of absorption in the absorber increased as the absorbent mass flow down onto the heat exchanger tube increased. However, the amount of absorption was saturated as the absorbent mass flow increased. We monitored the absorbent flow behavior in the heat exchanger tube. The gas–liquid surface area was not changed by the absorbent mass flow, and the thickness of the absorbent liquid film increased. The absorption rate coefficient was determined using the HFC-134a absorption transport model, and the absorber height was calculated for up-scaling. The calculation results revealed that, to achieve 80% of absorption equilibrium, the absorber height must be 4.3 times greater than the experimental value. Thus, the heat exchanger with high wettability must be designed with a high absorption rate.

亚热带不同次生林地凋落物持水特性及季节变化

为了解亚热带不同演替阶段次生林地的凋落物持水特性规律，选取湖南大山冲森林公园保存完好的三种亚热带典型次生林地，按两月一次采集新近的凋落物并采用水浸泡法测定凋落物持水量、持水率和吸水速率，对比分析不同森林类型凋落物持水性差异及其与凋落物碳氮凋落量的关系。结果表明：（1）三种次生林地凋落物量及组成均表现出特有的变化规律。针叶林和常绿阔叶林凋落物量以夏季5-9月最大，落叶阔叶林凋落物则以春、秋两个季节最大；（2）三种次生林地凋落物的饱和持水量、半饱和时间以及与水亲和力均呈现显著季节性变化特征。针叶林凋落物饱和持水量在5-7月达到最高为（59.68±2.91） g/m²，常绿阔叶林凋落物饱和持水量则在9月达到最高，落叶阔叶林凋落物饱和持水量在11月份达到最高为（190.60±8.81） g/m²；三种次生林凋落物的半饱和时间均以11月份为最低，且落叶阔叶林凋落物半饱和时间比其他两种次生林地更低，全年平均（0.62±0.12） h；凋落物的水亲和力系数，全年均以落叶阔叶林最大为142.72±26.12；（3）落叶阔叶林凋落物饱和持水率全年显著高于其他两种次生林（P<0.01），且针叶林和落叶阔叶林凋落物饱和持水率均在11月份达到最大值；（4）落叶阔叶林凋落物吸水速率A值显著低于其他两种次生林（P<0.01），而针叶林凋落物吸水速率系数B值显著高于其他两种次生林（P<0.01）；（5）凋落物饱和持水量与凋落物水亲和力和饱和持水率存在显著正相关关系，与凋落物凋落碳氮总量同样存在显著正相关关系；凋落物饱和持水率与凋落物半饱和时间、吸水速率系数A和B值存在显著负相关，与凋落物碳含量和C/N比极显著负相关，与凋落物氮含量极显著正相关（P<0.01）。综上，不同次生林类型凋落物持水性存在显著差异，凋落物持水性与凋落物碳氮量存在显著联系，该研究为深入探讨森林生态环境效应提供了支撑，丰富了森林凋落物持水特性的研究理论。;In order to understand litter water-holding characteristics in secondary forests under different succession stages, three typically subtropical secondary forests were selected in Dashanchong Forest Park in Hunan Province. New litters were collected in every two months and measured its water holding capacity, water holding rate and water absorption rate by water soaking method. Then, the water holding capacity of litters in different forest types were compared. The relationships were analyzed between water holding capacity and carbon and nitrogen contents in litters. The results showed that:(1) the amounts and composition of litters in the three secondary forests presented unique changes. The amounts of litters in coniferous forest and evergreen broad-leaved forest were the largest from May to September in summer, while amounts of litters in deciduous broad-leaved forest were the largest in spring and autumn. (2) The saturated water holding capacity, half saturation time, and water affinity coefficients of litters in three secondary forests exhibited significantly seasonal variation characteristics. The saturated water holding capacity in coniferous forest litters reached a maximum of (59.68±2.91) g/m² from May to July, and the saturated water holding capacity in evergreen broad-leaved forest reached a maximum in September; the saturated water holding capacity of deciduous broad-leaved forest reached (190.60±8.81) g/m² in November. The half saturation time of litters in the three secondary forests was the lowest in November, and the half saturation time in deciduous broad-leaved forest litters was lower than that of other two forests types, with an annual average of (0.62±0.12) h; the litters' water affinity coefficient was 142.72±26.12 in deciduous broad-leaved forest in the whole year. (3) The saturated water holding rate of litters in the deciduous broad-leaved forest was significantly higher than that in the other types throughout the year (P<0.01). The saturated water holding rate of litters in coniferous forest and deciduous broad-leaved forest reached the maximum in November. (4) The water absorption rate coefficient A of litters in deciduous broad-leaved forest was significantly lower than that in the other types (P<0.01), while the water absorption rate coefficient B in coniferous forest litters was significantly higher than that in the other types (P<0.01). (5) The saturated water holding capacity of litters showed significantly positive correlations with water affinity coefficients, saturated water holding rate, the total amount of carbon and nitrogen in litters. The saturated water holding rate showed significantly negative correlation with half saturation time and water absorption rate coefficient A and B, significantly negative correlations with carbon content and C/N ratio in litters, and significantly positive correlations with nitrogen content in litters (P<0.01). In summary, the water holding capacity of litters in the three secondary forests were significantly different. The water holding capacity was significantly correlated with carbon and nitrogen content in litters. This study enriches the research theory of litter water-holding characteristics and provides a theoretical basis for in-depth discussion of the ecological and environmental effects of forest litters.

Photodestruction of Diatomic Molecular Ions: Laboratory and Astrophysical Application.

In this work, the processes of photodissociation of some diatomic molecular ions are investigated. The partial photodissociation cross-sections for the individual rovibrational states of the diatomic molecular ions, which involves alkali metals, as well as corresponding data on molecular species and molecular state characterizations, are calculated. Also, the average cross-section and the corresponding spectral absorption rate coefficients for those small molecules are presented in tabulated form as a function of wavelengths and temperatures. The presented results can be of interest for laboratory plasmas as well as for the research of chemistry of different stellar objects with various astrophysical plasmas.

Panax quinquefolium saponin liposomes prepared by passive drug loading for improving intestinal absorption

Panax quinquefolium saponin (PQS) composed of 45% pseudo-ginsenoside F11 (PF11), is a natural mixture of sterol compounds obtained from the American ginseng plant, having numerous promising benefits for health. However, low solubility and permeability limit the development of PQS as a therapeutic agent for oral administration. In this study, PQS liposomes (PQS-Lips) were prepared by thin layer hydration, an in situ single-pass intestinal perfusion (SPIP) model was used to verify the improvement of membrane permeability of PQS-Lips. PQS-Lips had a high encapsulation efficiency (EE) of 65%∼70%, a particle size about 100.0 nm, and a zeta potential of −60 mV with regular spherical surface. FTIR and DSC showed the PQS in liposomes were amorphous, indicating that hydrogen bonds formed between one or several hydroxyl groups in PQS and C-O group at the phospholipid polar terminal. In addition, PQS-Lips showed sustained release in vitro than PQS at pH 1.2 and pH 6.8, and PQS-Lips had good stability in simulated gastric and intestinal fluid. Then, the absorption rate (K a) and effective permeability coefficient (P eff) of PQS-Lips in the whole small intestine were significantly higher than those in PQS solution (PQS-Sol), which proved that the PQS-Lips could significantly increase the membrane permeability of PQS and promote its absorption in the small intestine. From the experimental results, it could be known that liposome technology could effectively improve the absorption of PQS in the small intestine.

Correlation between Ultrafiltration Coefficient and Effective Lymphatic Absorption Rate in Continuous Ambulatory Peritoneal Dialysis Patients: A Possible Paradigm Shift.

Background:The relative contribution of transcapillary water movement and lymphatic reabsorption in peritoneal dialysis (PD) is a critical issue, particularly in patients with ultrafiltration failure (UFF). Based on routine results obtained from the PD Adequest 2.0 software, the present study aimed to re-evaluate the separate effects of transcapillary water movement and lymphatic reabsorption on the net ultrafiltration capacity in continuous ambulatory peritoneal dialysis (CAPD) patients without UFF. Methods:Seventy CAPD patients without UFF and PD duration less than 2 years entered the study. The study was conducted during January-April 2016 at Mashhad University of Medical Sciences, Mashhad, Iran. Each patient had 1 to 3 peritoneal equilibration test (PET) results which were used to analyze the determinants of fluid transport, lymphatic reabsorption, and ultrafiltration. Pearson and Spearman correlation tests were used to determine the correlation between continuous and ordinal factors, respectively. The data were analyzed using the SPSS software version 19.0. Results:In terms of the effective lymphatic absorption rate (ELAR) and ultrafiltration coefficient (LpA) values, there was no difference in the high or high-average transporters compared to the low or low-average transporters. However, a positive and highly significant correlation between ELAR and LpA was found. Conclusion: A significant correlation between ELAR and LpA was found in CAPD patients without UFF and duration less than 2 years from the beginning of PD. The abstract was presented in the 53rd ERA-EDTA Congress, Austria, as a poster and published in Nephrology Dialysis Transplantation as a supplement (2016; Vol. 31).

Impact on intestinal permeability of pediatric hyperosmolar formulations after dilution: Studies with rat perfusion method

IntroductionThere is no consensus on administering hyperosmolar formulations by mouth to neonates. In 1976, the Committee on Nutrition of the American Academy of Pediatrics published a recommendation of not administer formulations with an osmolarity higher than 400 mOsm/L due to the possible damage to intestine and relationship with necrotizing enterocolitis. Since this recommendation, exists a general trend of reducing osmolality of oral formulations without considering the pharmacokinetics of absorption of the drugs.The objective of this study was to characterize the permeability values of drugs formulated at different osmolalities by using a well-established rat intestinal perfusion model and to measure the osmolality of the most used formulations in our neonatology unit. MethodsFor the osmolality measurement study, most common used oral drugs were selected (compounded formulations and drug products). Osmolality of three dilutions (1:1, 1:4 and 1:8) were measured using a cryoscopic descent osmometer.Atenolol, caffeine, furosemide, hydrocortisone and paracetamol were selected for the permeability study. Three suspensions were elaborated of each drug (150 mOsm/kg, 300 mOsm/kg and 1500 mOsm/kg). Permeability values and absorption rate coefficients were determined in complete small intestine using in situ “closed loop” perfusion method. ResultsThe formulations that resulted to be hyperosmolar (>400 mOsm/kg) were 86% (70% of these proved to be above 1500 mOsm/kg).The permeability study shown that the osmolality is inversely proportional to the apparent permeability of the drug in the studied drugs. The permeability values obtained with hyperosmolar samples were lower compared to 150 mOsm/kg or 300 mOsm/kg. ConclusionsOsmolality parameter is of particular relevance in oral drug administration in neonate because the risk of damaging the gastrointestinal tract and because of the risk that modifying osmolality also modifies its permeability, resulting in a potential change in bioavailability.

Challenges and opportunities for assessing transport properties of high-performance concrete

In this paper, a review of techniques is given so that both, the challenges and opportunities for assessing transport properties of high-performance concrete, are highlighted. A knowledge of performance of structural concrete is required for design and compliance purposes. One driving force for the use of high performance concretes (HPC) is enhanced durability yet it would be wrong to assume that all HPCs can deliver the desired performance level. In situ characterisation of the permeation properties of concrete is the most viable means for assessing durability and has become increasingly important over the past 20 years. A variety of methods exist that provide a range of parameters, e.g. air permeability, water absorption rate, sorptivity and chloride migration coefficient.

Inhibitory Effects of Benzaldehyde, Vanillin, Muscone and Borneol on P-Glycoprotein in Caco-2 Cells and Everted Gut Sac

Aims: In clinical practice, herbal medicines have played an important role in the modulation of drug transporters through the combination of conventional prescription drugs, which necessitates the elucidation of herb-drug interactions. The present study was designed to investigate the inhibitory effects and mechanisms of benzaldehyde, vanillin, muscone, and borneol on P-glycoprotein (P-gp). Methods: The effects of the 4 compounds on the intracellular accumulation of rhodamine-123 (Rho-123) in vinblastine-treated Caco-2 (VB-Caco-2) cells were studied by monitoring fluorescence intensity through a flow cytometry assay, and the effects of these compounds on Rho-123 transport through VB-Caco-2 monolayers and Rho-123 intestinal absorption in the rat everted gut sac were investigated by high-performance liquid chromatography. Moreover, P-gp expression in VB-Caco-2 cells was assessed using flow cytometry and Western blot analysis, and the relative ABCB1 mRNA level was determined by Real-time RT-PCR. Key Findings: The results showed that benzaldehyde, vanillin, muscone, and borneol significantly increased Rho-123 uptake in VB-Caco-2 cells, increased the absorption rate and apparent permeability coefficient of Rho-123 in rat jejunum and ileum, and decreased the efflux ratio of Rho-123 from 6.52 to less than 2 during transport across VB-Caco-2 cell monolayers. In addition, these compounds reduced the protein and ABCB1 mRNA levels of P-gp in VB-Caco-2 cells. Conclusions: These data indicate that benzaldehyde, vanillin, muscone and borneol could effectively reverse multidrug resistance via inhibiting the P-gp function and expression pathway. The data provide fodder for further investigation into the interaction between the 4 compounds and other drugs transported by P-gp.

CO2 Capture and Crystallization of Ammonia Bicarbonate in a Lab-Scale Scrubber

A lab-scale bubble-column scrubber is used to capture CO2 gas and produce ammonia bicarbonate (ABC) using aqueous ammonia as an absorbent under a constant pH and temperature. The CO2 concentration is adjusted by mixing N2 and CO2 in the range of 15–60 vol % at 55 °C. The process variables are the pH of the solution, temperature, gas-flow rate and the concentration of gas. The effects of the process variables on the removal efficiency (E), absorption rate (RA) and overall mass-transfer coefficient (KGa) were explored. A multiple-tube mass balance model was used to determine RA and KGa, in which RA and KGa were in the range of 2.14 × 10−4–1.09 × 10−3 mol/(s·L) and 0.0136–0.5669 1/s, respectively. Results found that, RA showed an obvious increase with the increase in pH, inlet gas concentration and gas temperature, while KGa decreased with an increase in inlet gas concentration. Using linear regression, an empirical expression for KGa/E was obtained. On the other hand, ammonia bicarbonate crystals could be produced at a pH of 9.5 when the gas concentration was higher than 30% and γ (=Fg/FA, the gas-liquid molar flow rate ratio) ≥ 1.5.

Design of SiO2/PMHS hybrid nanocomposite for surface treatment of cement-based materials

A silica-based hybrid nanocomposite, SiO2/polymethylhydrosiloxane (SiO2/PMHS), is synthesized by a sol-gel process and used for surface treatment of hardened cement-based materials. The advantages of both normal organic and inorganic silica-based treatment agents are explored. Results revealed a covalent chemical bonding of SiO2 and PMHS and the SiO2/PMHS showed hydrophobicity and pozzolanic reactivity when used for surface treatment. Greater reductions of the water absorption rate and gas permeability coefficient of cement-based materials were achieved by the hybrid nanocomposite compared to its individual components, showing synergistic effects of hydrophobicity and pore refinement characteristics as proved by the measurements of the contact angle, the mineralogy, the morphology and the porosity. The results showed promising advantages of using silica-based hybrid nanocomposite for surface treatment to achieve a higher surface quality. Moreover, it can be suggested that more functionalities of the cement-based materials can be tailored through the design and use of the silica-based hybrid materials.