Absorption Factor Research Articles

Simultaneous estimation of recently FDA approved co-formulated ophthalmic solution benoxinate and fluorescein: Application to aqueous humor

Nine simple, cost-effective, and sensitive spectrophotometric methods were developed to simultaneously assay benoxinate HCl and fluorescein sodium in their co-formulated eye drops without barring common excipients. A direct UV spectrophotometric method (method I) was developed for their FLU assay at 481 nm over the concentration range of 0.6–10.0 μg mL−1. Meanwhile, BEN was assayed over the concentration range of 1.0–25.0 μg mL−1 by different UV based methods, namely, conventional dual-wavelength method (DW) (method II), first derivative1D spectrophotometry (method III), second derivative2D spectrophotometry (method IV), ratio spectra difference spectrophotometry (method V), the first derivative of ratio spectra (method VI), ratio subtraction method (method VII), isosbestic point method (ISP) (method VIII) and absorption factor method (method IX). The performance of the proposed methods was assessed relying on the correlation coefficients, relative standard deviations, and limits of detection and quantitation. The variance ratio F-test and Student t-test showed no significant differences between the obtained results of the developed methods and those of reference methods. The proposed methods were also applied to determine studied drugs in commercial eye drops and aqueous humor.

Effects of Ghrelin on intestinal cell proliferation, the expression of protein absorption and metabolism factors in juvenile grass carp (Ctenopharyngodon idella)

Ghrelin can stimulate pituitary growth hormone (GH) release, and has a key role in the regulation of food intake and adiposity in vertebrates. At present, no relevant studies have reported the effects of Ghrelin on intestinal cell proliferation, protein absorption and metabolism. In this paper, firstly we established the intestinal epithelial cell lines of juvenile grass carp (Ctenopharyngodon idella) that can be passed stably and identified by the intestinal specific expression proteins E-cadherin and ZO-1. And we used this cell line as a model to investigate the effects of Ghrelin, Ala-Gln, Ala-Gln+Ghrelin on the proliferation of juvenile grass carp intestinal cells. We found that the use of Ghrelin, Ala-Gln and Ala-Gln+Ghrelin could promote the proliferation of intestinal cells of juvenile grass carp, but Ala-Gln+Ghrelin had the strongest promoting effect. Further, we investigated the effects of Ghrelin on the expression of cdx2, PepT1 and mTOR which are related to intestinal cell proliferation, protein absorption and metabolism of grass carp in vitro and in vivo experiments. And we studied the effects of different protein sources on the expression of Ghrelin, PepT1 and mTOR in grass carp at individual level. The results suggested that Ghrelin can promote grass carp intestinal cell proliferation, and affect the expression of genes which are related to intestinal peptide absorption and metabolism in juvenile grass carp.

Impact of additives on the structural, elastic, optical and radiation resisting aptitude of the highly dense Sm3+ doped multicomponent glasses

To perceive the direct effect of additives on the physical, structural, optical and radiation attenuating qualities, a broad spectrum of experimental and numerical analyses was conducted on the Sm3+ ions activated heavy metal ions bolstered multi component glasses. The density, XRD, SEM, FTIR and the absorption spectroscopic techniques supported in examining the structure of the proposed multi component glasses. The Zn containing glass (BTSZn) is observed to possess a tightly packed structure from the evaluation of boron-boron distance (SB−B), oxygen packing density (OPD) and elastic moduli. Additionally, evaluation of few of the effective optical features like band gap energy (Eopt), urbach energy (ΔEU) and two photon absorption factor (TPA) and JO analysis were achieved from the absorption analysis. The gamma shielding evaluation of the glasses was conducted employing Phys-X software package. Seemingly, the Zn and Ba containing glasses (BTSZn and BTSBa) were perceived to hold the largest linear attenuation coefficient (LAC) compared to the rest of glasses indicating good attenuation aptitude. The glass containing Li (BTSLi) has the highest tenth value layer (TVL) depending upon the heavy metal ions. Speaking of radiation shielding ability, the greater effective atomic number (Zeff) classically implies that the BTSBa glass has the supreme potential in this field. The inclusion of the Zn and Ba additives have appreciably raised up the nuclear attenuation qualities by maintaining other material features within practical range which will be appreciated by the scientific community to extend this work for forthcoming generation.

Stacked Reticular Frame Boosted Circularly Polarized Luminescence of Chiral Covalent Organic Frameworks

AbstractChiral covalent organic frameworks (COFs) with circularly polarized luminescence (CPL) are intriguing as advanced chiroptical materials but have not been reported to date. We constructed chiroptical COF materials with CPL activity through the convenient Knoevenagel condensation of formyl‐functionalized axially chiral linkers and C3‐symmetric 1,3,5‐benzenetriacetonitrile. Remarkably, the as‐prepared chiral COFs showed high absorption and luminescent dissymmetric factors up to 0.02 (gabs) and 0.04 (glum), respectively. In contrast, the branched chiral polymers from the same starting monomers were CPL silent. Structural and spectral characterization revealed that the reticular frame was indispensable for CPL generation via confined chirality transfer. Moreover, reticular stacking boosted the CPL performance significantly due to the interlayer restriction of frame. This work demonstrates the first example of a CPL‐active COF and provides insight into CPL generation through covalent reticular chemistry, which will play a constructive role in the future design of high‐performance CPL materials.

Stacked Reticular Frame Boosted Circularly Polarized Luminescence of Chiral Covalent Organic Frameworks.

Chiral covalent organic frameworks (COFs) with circularly polarized luminescence (CPL) are intriguing as advanced chiroptical materials but have not been reported to date. We constructed chiroptical COF materials with CPL activity through the convenient Knoevenagel condensation of formyl-functionalized axially chiral linkers and C3-symmetric 1,3,5-benzenetriacetonitrile. Remarkably, the as-prepared chiral COFs showed high absorption and luminescent dissymmetric factors up to 0.02 (gabs ) and 0.04 (glum ), respectively. In contrast, the branched chiral polymers from the same starting monomers were CPL silent. Structural and spectral characterization revealed that the reticular frame was indispensable for CPL generation via confined chirality transfer. Moreover, reticular stacking boosted the CPL performance significantly due to the interlayer restriction of frame. This work demonstrates the first example of a CPL-active COF and provides insight into CPL generation through covalent reticular chemistry, which will play a constructive role in the future design of high-performance CPL materials.

Synthesis of cellulose based super absorbent and its excellent oil–water separation properties

AbstractThe work reported aims to developing the grafted cellulose fiber‐based material (polyethylene wax‐grafted maleic anhydride)/cellulose fiber; PEW‐g‐MA/CF) for efficient absorption of oil from aqueous solution. PEW‐g‐MA/CF was prepared via grafting modification between cellulose fiber and the maleic anhydride modified polyethylene wax, resulting in a cost‐effective approach for synthesizing cellulose‐based oil super absorbent. The as‐prepared PEW‐g‐MA/CF was systematically characterized via Fourier‐transform infrared, atomic force microscope, and thermogravimetric; the influencing factors of oil absorption, including the weight ratio of the raw materials, reaction temperature, and reaction time, were studied and compared. The maximum oil absorbency was up to 19.36 g/g‐1 with the condition of weight ratio 1:1; temperature 60°C; and reaction time 3 h. Overall, PEW‐g‐MA/CF is an environmentally friendly and cost‐effective material for high oil absorption from aqueous solution, and the valuable findings might provide an idea for maximizing the potential of the cellulose‐based absorbents for a variety of applications.

Sinc and discrete singular convolution for analysis of three‐layer composite of perovskite solar cell

This work studies the performance of composite solar cell model consisting of perovskite absorber layer (CH3NH3PbI3), electron transport layer (TiO2 or PCBM), and hole transport layer (Spiro-OMeTAD or CuI) via sinc and discrete singular convolution quadrature techniques. The governing equations for hole transport layer, electron transport layer, and absorber layer (perovskite) are derived depending on the equations of continuity and Poisson. Different quadrature and block-marching techniques convert these equations to the nonlinear algebraic system. Then, we apply the iterative method to solve the problem of nonlinearity. For each scheme, a programmed code is designed to get a numerical solution for composite perovskite solar cells by MATLAB. To ensure the efficiency and convergence of these schemes, the obtained results match with previous experiments and other numerical schemes. From these comparisons, the discrete singular convolution quadrature technique gives high accuracy, speed of convergence, and more reliability than other methods with error up to 10−8. Consequently, the effects of different thicknesses, mobilities, band gaps, temperatures, absorption factors, wavelengths, and doping concentrations on current density, open-circuit voltage, and efficiency of solar cells are investigated in a full parametric study. Hence, the obtained effects of the current schemes increase the efficiency of perovskite solar cells. Novelty Statement Sinc and discrete singular convolution quadrature techniques are applied to reach high performance for perovskite absorber layer sandwiched between electron transport layer (ETL) and hole transport layer (HTL). The study demonstrates that the discrete singular convolution quadrature method gives high efficiency and accurate results at different parameters. It is obtained that the power conversion efficiency is approximately 35% at specific parameters.

Development of Prediction System for Drug Absorption after Intranasal Administration Incorporating Physiologic Functions of Nose -Estimation of in Vivo Drug Permeation through Nasal Mucosa Using in Vitro Membrane Permeability

The nasal drug application has drawn much attention as the strategy for the delivery route of many drug modalities such as the poorly absorbed drugs, peptides, nucleic acid, and central nervous system drugs. The absorption of drug after intranasal (IN) application depends on the nasal residence time of applied drug, affected by mucociliary clearance (MC). MC is a decisive factor in the nasal absorption of drug. We describe the establishment of in vitro evaluation system of nasal MC via the moving velocity of a marker particle on nasal mucosa, and the development of the pharmacokinetic model to which in vitro parameters on nasal MC was incorporated to enable the prediction of drug absorption after IN application. Moreover, the pharmacokinetics of norfloxacin after IN application was investigated using MC-modified rats pretreated with MC modulators. Nasal absorption fluctuated due to changes in the nasal residence time of drug in response to changes in MC. The prediction system enables quantitative evaluation of changes in drug absorption associated with MC fluctuations. In addition, for a precise prediction system for drug absorption after IN application from the drug absorption model, the relationships between in vitro drug permeability through Calu-3 layers, in vivo transnasal permeation of drug and in vivo bioavailability after IN application were evaluated. The significant correlations between these parameters were obtained, suggesting that transnasal permeability and drug absorption after IN application can be predicted from in vitro membrane permeability.

Simultaneous estimation of tramadol and piroxicam by UV spectrophotometer and RP-HPLC

Several clinical studies have shown that the use of a combination of Tramadol and Piroxicam has displayed a better analgesic effect than the individual drug with the occurrence of fewer side effects. As such, there is no analytical method available for Qualitative and Quantitative determination of particular drugs in both combinations. Different analytical techniques can be applied for multicomponent analysis, including; spectrophotometer, chromatography, and electrophoresis. In the present work, the analytical methods of qualitative and quantitative analysis for combinations of Tramadol and Piroxicam have been used employing UV spectrophotometer and HPLC. Two simple, accurate, rapid, and selective analytical procedures were developed and validated for the simultaneous estimation of Tramadol HCl and Piroxicam using UV spectrophotometer and High-performance liquid chromatography with UV detection (HPLC-UV). The absorption Subtraction technique was utilized in the Simultaneous determination of the UV spectrophotometer. The HPLC method employs a C18 Phenomenex column (250 × 4.6, 5 µm), 20 µL injection volume, column temperature controlled at 30° C, detection at 282 nm, Trifluoroacetic acid-pure acetonitrile (70: 30 v/v) mobile phase pumped at the rate. Parameters consisting of linearity, precision, accuracy, robustness, ruggedness, detection and quantitation are studied. From the investigations, the Absorptive factor of Tramadol HCl and Piroxicam at both the isosbestic points has been found. The percentage assay of 108.73 ± 1.61 % and 104.54 ± 0.94 % for Tramadol HCl and Piroxicam. The objective of validation of analytical procedures is to demonstrate that it is suitable for its intended purpose.

Enhanced Visible-Light Absorption of Fe2O3 Covered by Activated Carbon for Multifunctional Purposes: Tuning the Structural, Electronic, Optical, and Magnetic Properties.

Visible-light absorption is a critical factor for photocatalyst activity and absorption of electromagnetic (EM) interference application. The band gap of Fe2O3 is 2 eV, which can be increased by doping with a high-band-gap material such as carbon from activated carbon (AC) with a band gap of 4.5 eV for increased visible-light absorption. The porosity decreases from 88 to 81.6%, and the band gap increases from 2.14 to 2.64 eV by increasing the AC from 10 to 25%, respectively. The photocatalytic activity takes 120 min to produce a harmless product for 10–20% AC, but 25% AC shows 89.5% degradation in only 90 min and the potential to attenuate the EM wave up to 99% due to the RL being below −20 dB. The second- and third-cycle degradation achieved by the composite Fe2O3–AC having 25% AC is 88.2 and 86.5% in 90 min, respectively. The pore of the surface state of AC contains a trapped charge, and interaction occurs between the charge (electron/hole) and O2 or H2O to produce OH and superoxide (O2–) radicals. These radicals move inside the molecule of the pollutant (methylene blue (MB)) to break up the bond, with the final products being H2O and CO2. The X-ray photoelectron (XPS) spectra show that oxygen plays a key role in the interatomic bonding with Fe, C, and MB atoms. The best absorption of EM interference is −21.43 dB, with degradation reaching 89.51% in only 90 min for 25% AC due to its higher band gap and anisotropy constant. Fe2O3–carbon is a multifunctional material for the green environment because of its electromagnetic interference absorption and photodegradation of wastewater.

Does Chemotherapy-Induced Gastrointestinal Mucositis Affect the Bioavailability and Efficacy of Anti-Infective Drugs?

Antimicrobial prophylaxis is increasingly being used in patients with hematological malignancies receiving high-dose chemotherapy and hematopoietic stem cell transplantation (HSCT). However, few studies have focused on the potential impact of gastrointestinal mucositis (GI-M), a frequently observed side effect of chemotherapy in patients with cancer that affects the gastrointestinal microenvironment, on drug absorption. In this review, we discuss how chemotherapy leads to an overall loss of mucosal surface area and consequently to uncontrolled transport across the barrier. The barrier function is depending on intestinal luminal pH, intestinal motility, and diet. Another factor contributing to drug absorption is the gut microbiota, as it modulates the bioavailability of orally administrated drugs by altering the gastrointestinal properties. To better understand the complex interplay of factors in GI-M and drug absorption we suggest: (i) the longitudinal characterization of the impact of GI-M severity on drug exposure in patients, (ii) the development of tools to predict drug absorption, and (iii) strategies that allow the support of the gut microbiota. These studies will provide relevant data to better design strategies to reduce the severity and impact of GI-M in patients with cancer.

Research on Information Flow Mechanism of Manufacturing Enterprises from the Perspective of Innovation Value Chain

AbstractManufacturing enterprises always generate, acquire, and transform large amount of information which flows across every link of their innovation process and value chain. Information flow is one of the basic conditions for information to be reproduced, utilized and value added. Unreasonable paths and transmission methods of information flow will lead to problems such as poor flow efficiency, low information sharing and even information silos, which will further restrict the R&D innovation and service upgrade. Optimizing information flow mechanisms and paths is a vital part for improving the innovation capability of manufacturing enterprises. In order to reflect the interactions, flow‐path differences and nonlinear laws among manufacturing enterprises' innovation units and to reveal relations between information‐flowing efficiency and innovation capabilities, the paper divides innovation activities of manufacturing enterprises into three phases, such as information acquisition, information transformation and information value addition based on the theory of innovation value chain, and puts forward a mathematical model of information absorption and transformation to ultimately reveal the mechanisms for information flow across inside and outside units. Further, the paper takes a non‐linear function for absorptive capacity based on level of experiential knowledge, continuous R&D intensity, and agent relation strength to quantify the information absorption and transformation process and takes index of innovation information amount and cumulative information amount to calculate innovation abilities and measure information value addition. Finally, the paper uses simulation tool to analyze the influencing factors of information absorption and transformation optimization.

Blast Resistance of an Innovative Helmet Liner composed of an Auxetic Lattice Structure

Helmet liners are employed to prevent or reduce head injuries caused by impact or blast loads. Liners minimize the damage by shock attenuation and absorbing the dynamic energy. In order to improve blast resistance and crashworthiness characteristics of helmet liner under air-blast, in the present study, an innovative structure designed by an arrow-head auxetic lattice structure is suggested to replace the conventional EPS foams usually employed in the liner section. Explicit finite element method is employed to model the innovative helmet structure under blast loading and results are compared with the conventional case based on trend of acceleration, energy absorption, weight, and Head Injury Criteria (HIC) factor. Also, a parametric study is conducted on the effect of lattice structure’s cell size in the protective performance of helmets. Results indicate a great improvement in blast resistance of helmet when the suggested liners are employed so that the HIC number could be decreased by 71% when AH4 configuration is used while the overall energy absorption capacity of helmet is increased about 34% compared to the basic model.

Amine infused hydrogel-based CO2 gas storage technology for CO2 hydrate-based cold thermal energy storage

Carbon dioxide (CO2) hydrate-based cold thermal energy storage (CTES) is a promising method for load shifting and demand management of cooling systems and for CO2 utilisation. A challenge of CO2 hydrate-based CTES is to find a compatible CO2 gas storage, the CO2 regeneration and absorption conditions of which can be coupled with the charging and discharging conditions of the CTES, respectively. Amine diethanolamine infused hydrogels (DEAIHs) can be an effective CO2 absorber as the gas–DEA surface contact area is greatly enlarged by infusing the solution into a hydrogel. However, the influencing factors of the CO2 absorption and regeneration performance of DEAIHs are unknown. This paper investigates the performance of DEAIHs and explores the possibility of applying them in cyclic CO2 gas storage for CTES. The effects of pressure, temperature, DEAIH sample mass and amine diethanolamine (DEA) mass fraction on CO2 absorption and absorption rate are investigated. It was found that a higher pressure prompted CO2 absorption while a temperature of 12℃ resulted in the highest CO2 absorption rate. The average CO2 absorption rates in the first 100 min were 0.250, 0.228, 0.155 and 0.033 mmol min–1 for 20-g DEAIH sample with 30-wt% DEA and 60-g DEAIH sample with 30, 47 and 89-wt% DEA, respectively. CO2 regeneration from DEAIH under zero and non-zero gauge pressures are studied. Under non-zero gauge pressures, a pressure rise followed by a pressure drop caused by CO2 re-absorption appeared in the CO2 regeneration from DEAIH. It was found for the first time that the system passed through a meta-equilibrium state before it reached an equilibrium pressure. Cyclic absorption and regeneration at 110℃ under zero gauge pressure showed that the CO2 absorption decreased dramatically after the third cycle due to the volatility of amine. Operating a coupled CO2 hydrate-based CTES and CO2 gas storage system demonstrated the possibility of DEAIH material for CO2 gas storage in CTES systems.

Sensitive Hemoglobin Concentration Sensor Based on Graphene-Plasmonic Nano-structures.

In this paper, half-cylindrical-shaped rods are arranged in a row in order to form hemoglobin concentration sensors. The proposed structures can effectively detect hemoglobin concentrations in blood samples. Five individual structures based on graphene-plasmonic combinations are proposed and investigated. The proposed structures are made of different layers of Au, Ag, SiO2, and graphene. Different plates and cylindrical-shaped graphene layers are introduced in the structures to improve the functionality (absorption peak value and wavelength) of the absorber (sensor). Adding more Au layers strengthens the confinement of the incident electromagnetic waves and improves the absorption factor. Also, in the proposed structures, for improving the results, the effects of the chemical potential of graphene layers and “G” (graphene layer thicknesses) on the absorption peak and wavelength are considered. The final suggested structure indicates unity absorption peak and thus can be utilized in wide ranges of applications. As a refractive index bio-sensor, the structure is considered for detecting hemoglobin concentrations in blood samples which indicates a reasonable sensitivity factor of 570 nm/RIU.

Physiologically based pharmacokinetic/pharmacodynamic modeling to evaluate the absorption of midazolam rectal gel

ObjectiveWe aimed to 1) develop physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) models of a novel midazolam rectal gel in healthy adults, 2) assess the contribution of different physiologically relevant factors in rectal absorption, and 3) to provide supports for future clinical studies of midazolam rectal gel. MethodsWe developed the rectal PBPK model after built the intravenous and the oral PBPK model. Then, the physiological progress of rectal route was described in terms of the drug release, the rectal absorption and the particle first-pass elimination. Next, the validated PBPK model was combined with the sigmoid Emax PD model. This PBPK/PD model was used to identify the dose range and the critical parameters to ensure safety sedation. ResultsBased on the simulations, the recommended maximum dose for adults’ sedation was 15 mg. And the retention time of midazolam rectal gel should be longer than 3 h to reach over 80% pharmacokinetics and pharmacodynamics effects. ConclusionWe successfully developed a PBPK/PD model for the midazolam rectal gel, which accurately described the PK/PD behavior in healthy adults and indicated the transit time of rectum was the most sensitive parameter for absorption. This PBPK/PD model would be expected to support the future clinical studies and pediatric application.

DIFFERENT ULTRAVIOLET SPECTROSCOPIC METHODS: A RETROSPECTIVE STUDY ON ITS APPLICATION FROM THE VIEWPOINT OF ANALYTICAL CHEMISTRY

In routine practice, some simple and rapid analytical methods are needed for the assessment of formulations containing multiple elements, complex matrix system and for biotherapeutic products. There are several methods available for ultraviolet (UV) spectrophotometry that rely on the concept of absorbance difference, absorbance spectra, and additivity, also included in the list are simultaneous equation method, Q-absorbance ratio method, derivative spectrophotometry, ratio derivative spectra, successive ratio-derivative spectra, absorption and absorptivity factor method, and difference spectrophotometry along with multivariate chemometric methods. In this review, emphasis has been given to the theories, mathematical context, advantages, and disadvantages along with the vast applications of UV spectrophotometry. The findings further highlighted that for the analysis of drugs, UV spectrophotometry remains as one of the most simple, cheap, and promising option for routine practice in the field of pharmaceuticals.

Carbon footprint in Higher Education Institutions: a literature review and prospects for future research.

Higher Education Institutions (HEI) or universities, as organisations engaged in education, research and community services, play an important role in promoting sustainable development. Therefore, they are increasingly linked to the initiative of calculating their carbon footprint (CF), which is a tool to assess sustainability from the perspective of greenhouse gas (GHG) emissions. The aim of this study is to carry out a systematic review of the current situation of CF assessment in academic institutions by analysing different key elements, such as the time period, methodologies and practises, calculation tools, emission sources, emission factors and reduction plans. The review protocol considered articles published until March 2021. Of the articles reviewed, 35 are aimed specifically at calculating the CF of HEI, while the remaining articles consist of review, activity-specific CF assessment or GHG emission reduction articles. Clear differences have been identified when results are compared for the normalised CF (average of 2.67 t CO2e/student, ranging from 0.06 to 10.94) or the percentage of carbon offsetting, only considered in 14% of the studies and ranging from 0.09 to 18%. The main reason for this is the lack of standardisation as regards the time metric (year, semester), functional unit (student, employee, area) and data collection boundary (scope 1, 2, 3), the emissions sources and emission factors, mainly for scope 3 (water consumption and treatment, waste treatment, office, ICT and laboratory consumables, commuting and travel, construction materials, canteens, etc.), and the inclusion or not of the effect of carbon offset projects to offset the CF (aim of the project and absorption sources and factors). However, despite the differences, a reduction over time is clearly observed. Therefore, CF in HEI requires further improvements and solutions to a number of challenges, including the definition of representative emission sources, the creation of a robust emission factor database and the development of tools/methodologies that cover all the needs of this type of organisation.Graphic abstract

Characterization and Radiation Shielding Properties of Philippine Natural Bentonite and Zeolite

In this paper, the investigation of the structural and radiation shielding characteristics of natural bentonite and zeolite was presented. XRD (X-ray diffraction) and SEM (scanning electron microscopy) were used to examine the structural properties and morphologies of the minerals. The Electron-Photon Interaction Cross Sections 2017 (EPICS2017) library through EpiXS software was used to obtain the photon shielding properties – including mass attenuation coefficients, mean free paths, half-value and tenth-value layers, effective atomic numbers, and buildup factors for energy absorption and exposure. The ESTAR web program and SRIM code were used to obtain electron and ion stopping powers and ranges. The neutron removal cross-sections and the fast and thermal attenuation factors were obtained using the Phy-X/PSD, MRCsC, and NGCal software. The results showed that the zeolite grain sizes were typically smaller than 50 µm, while the bentonite grain sizes were larger reaching 100 µm. It was found that both materials were significantly composed of mordenite and montmorillonite. The photon shielding quantities for both materials showed similar MFP, HVL, and TVL values with different buildup factor values at large penetration depths. The high-energy charged particle range within both materials described similar trends and values. The range of alpha particles was significantly smaller than the average grain sizes for both materials. The fast neutron removal cross-sections of zeolite and bentonite were significantly higher than for typical soil values. Both natural materials may be suitable candidate ingredients for radiation shielding composites, especially due to their natural abundance and unique properties.

Electrically controlled transdermal delivery of naproxen and indomethacin from porous cis-1,4-polyisoprene matrix.

This study is focused on the inquiry of using a porous polymeric structure to absorb and release transdermally two drugs through a skin from deproteinized natural rubber latex (DPNR). The porous DPNR films were fabricated from the internal formation of surfactant micelles and their subsequent leaching out to generate porous structures. The pore size of DPNR films increased with increasing surfactant amount. The model drugs were naproxen and indomethacin; their releases and release-permeations were investigated under the effects of surfactant amount, electrical potential, and drug size. Without electric field, the drug release mechanism was mainly driven by concentration gradient. The higher amount of drug released was obtained from the matrix with a larger pore size. Under electric field, the higher amounts of drug release were obtained in the shorter drug release durations, via the electrorepulsive force between the negatively charged drugs and the cathode electrode. The molecular drug size was a factor for the drug absorption, release rate and amount. For the drug release-permeation experiment through the pig skin, there were two release-permeation periods as governed by the combination of concentration gradient and swelling in the first period, and the matrix erosion in the second period. The fabricated porous DPNR films have been shown here to be potential to be used as a transdermal patch with electrically controllable drug release rate, amount and duration along with the facile drug-matrix loading and absorption.