External Penetration Research Articles

Computer Tomography (CT)-Based Study to Investigate Feasibility and Efficacy of Thoracoscopic Surgery in the Treatment of Penetrating Chest Wall Tuberculosis.

Chest wall tuberculosis may develop if tuberculous (TB) lesions spread through the chest wall and invade the thoracic cavity. The presence of a mass on the patient's chest wall may be the first indication of TB, and a chest CT scan can help diagnose external penetrating chest wall TB, the incursion of tuberculosis from the lungs into the chest wall. This study examines the safety and efficacy of thoracoscopic-assisted surgery for the treatment of penetrating chest wall tuberculosis as a means of exploring novel concepts of minimally invasive surgery. Our hospital conducted a retrospective study of 25 patients with penetrating chest wall TB who underwent thoracoscopic surgery between January 2020 and June 2021. General demographics, CT scan data linked to surgery, and postoperative patient outcomes were compared between the two groups. The data was also evaluated to determine the range of operation time and the volume of bleeding from different foci in the thoracic cavity. All procedures went well after patients took conventional antituberculosis medication for at least two weeks prior to surgery. CT scans showed that thoracoscopic surgery needed a smaller incision than traditional chest wall TB surgery, with no discernible increase in surgical time. Postoperative tube use, length of hospital stay, and blood loss were all significantly lower than they would have been with conventional surgery. In addition, thoracoscopy was associated with a significantly reduced rate of subsequent treatment. Fibrous plate development and calcification caused the longest operation times in the thoracoscopic surgery group, whereas multiple pleural tuberculomas generated the most hemorrhage. Thoracoscopic surgery usually reveals tuberculous foci hiding in the thoracic cavity. Thethoracic surgery can eliminate the TB focus in the chest wall and intrathoracic while treating penetrating chest wall tuberculosis. The CT scan is a crucial part of the diagnostic process for these patients. Minor surgical trauma, low complication and recurrence rates, and good results. There is a greater distinction between the two surgical approaches for patients with penetrating chest wall TB as opposed to those with basic chest wall tuberculosis.

Effect of carbonation curing on distribution and binding capacity of chloride ions in cement pastes

Carbonation curing of concrete is an effective measure to reduce CO2 emissions, but it can adversely affect chloride binding capacity of cement pastes and its durability. In this study, the chloride ion content and phase assemblages of cement pastes under three curing conditions: standard curing, carbonation curing, and mixed curing (7-day carbonation curing and 21-day standard curing) were investigated based on combined macroscopic and microscopic methods. The chloride ions were introduced into cement pastes either through internal incorporation during the mixing process or from external penetration during its immersion in chloride contained solutions. Experimental results show that a large number of internally incorporated chloride ions were accumulated in the surface layer of pastes due to moisture evaporation during carbonation curing process. The transport of internally incorporated chloride ions in the paste under the mixed curing process was affected by the coupling effects of carbonation and capillary suction, resulting in inward migration of chloride ions. The external chloride ions from the solution penetrated into paste through initial diffusion and subsequent capillary suction during carbonation curing and mixed curing processes. Neither internally-incorporated nor externally-penetrated chloride ions could be bound in the carbonated zone, and the Friedel's salt could not be formed either. Due to the decrease of carbonation effect along the penetration depth and inward migration of chloride ions, the bound chloride ion content increased and formed a peak value in the inner layer.

Study on spray characteristics of fan nozzle in an afterburner environment

In this study, an innovative fan nozzle was designed to improve the ignition and cross-flame performance of the integrated afterburner and the spray characteristics of the fan nozzle in an afterburner environment were studied. A laser particle analyzer and a high-speed camera were used to study the impact of pump pressure and inlet air parameters on Sauter mean diameter (SMD) distribution, penetration depth and atomization angle. The results showed that the spatial fuel distribution was a complex three-dimensional (3D) fuel field, which included three regions: upwind, core, and leeward areas. The SMD decreased as the pump pressure increased, and the SMD increased with the increase temperature. The penetration depth in the cross air was divided into internal and external penetration; the internal and external penetration depths increased firstly and then tended to be stable as the pressure. The internal and external penetration depths decreased as cross air velocity; the increase in temperature and pressure of cross air could make the internal and external penetration depth decrease. The cross air parameters and pump pressure were very important parameters. The atomization angle increased as the pump pressure and the atomization angle decreased as cross air velocity. The atomization angle decreases as the cross air temperature slightly. The results showed that fan nozzles were more suitable for ignition and cross flame in the cavity of the afterburner than the direct injection nozzles.

Mechanical Damage Test and Model Study of Layered Composite Rock Based on Acoustic Emission and DIC Characteristics

To study the mechanical damage characteristics of layered composite rocks, sandstones, and mudstones of deep tight reservoirs were used as the research objects, and layered composite class rocks were prepared by similar material model tests. Uniaxial compression tests were conducted and supplemented with AE (Acoustic Emission) system and DIC (Digital Image Correlation) system to obtain the physical and mechanical parameters such as strength and elastic modulus of the layered composite rocks. The corresponding law of AE ringing count and rock damage evolution was studied and the damage process of layered composite rock under uniaxial loading was divided into three stages: initial damage, stable damage development, and damage acceleration. Analysis of strain cloud diagrams of the DIC system revealed that the deformation characteristics of the layered composite rock under uniaxial were mainly tensile-shear-slip damage. Based on the internal damage evolution characteristics of AE and the surface damage evolution characteristics of DIC, a damage constitutive model of layered composite rocks based on the dual damage factor characterization was established, which reasonably revealed the damage evolution mechanism of internal structure development and external crack germination, extension and penetration of layered composite rocks under uniaxial compression.

133 Simulations of pH-effects on kallikrein activity predict compromised skin barrier and predisposition to irritations and dryness characteristic of atopic dermatitis

Skin barrier function is a crucial element in the pathophysiology of atopic dermatitis (AD). Even non-lesional skin of AD patients is clinically characterized by a compromised barrier compared to healthy cohorts. This is often due to the increased kallikrein (KLK) activity also related to increased skin pH. The aim of our work is to develop a computational model of compromised skin barrier characteristic of non-lesional AD skin. A dynamic agent-based model of healthy adult epidermis is adapted to include a previously published mathematical model of KLK activity and its influence on desquamation. Parameter values are then modified to represent the increase in KLK activity, due to the increased skin pH, observed in AD skin. Simulations of the two models (healthy and compromised) are compared in terms of model emerging parameters like the thicknesses of the stratum corneum (SC) and the viable epidermis (VE), the total amount of a topically applied substance that permeates in the SC and the VE, the resistance to water transport in the SC and the transepidermal water loss (TEWL). Increased KLK activity results in weakening of the skin barrier function, in both directions: inside-out (water loss) and outside-in (external penetration). The SC of the compromised skin model is 15% thinner compared to the model of healthy epidermis. TEWL is increased by 9% and the amount of the externally applied substance that permeates in the VE by 18.5%. Resistance to water transport is decreased particularly in the lower part of the SC. These results are in agreement with published data comparing healthy and non-lesional AD skin. This study emphasizes the important role played by skin pH and KLK activity. It shows that an increase of KLK activity due to more alkali pH alone affects both the skin permeability to external irritants and its capacity to retain water. These effects can begin to explain the predisposition of such skins to irritation and skin dryness characteristic of AD.

A novel model for regional indoor PM2.5 quantification with both external and internal contributions included

PM2.5 (particulate matter with an aerodynamic size ≤ 2.5 μm) of indoor origins is a dominant contributor to the overall air pollution exposure. Although some sophisticated models have been developed to simulate indoor air quality for individual households, it is still challenging to quantify indoor PM2.5 on a regional scale, which is critical for health impact assessments. In this study, a new model was developed to predict indoor PM2.5 concentrations by quantifying the external penetration, as well as the internal contributions. The model was parameterized based on a set of simultaneously measured indoor and outdoor PM2.5 concentrations at five-second temporal resolution for 53 households in Beijing. This study found that indoor PM2.5 concentrations were significantly correlated with those in the outdoor environment with an approximately 1-h lag-time on average. Outdoor-to-indoor penetration dominated the contribution to indoor PM2.5 during polluted hours with relatively high ambient PM2.5 concentrations, while the indoor PM2.5, during clean hours, was contributed by internal sources, including smoking, cooking, incense burning, and human disturbance. The influence of windows, house area, and air purifier use was addressed in the new model. The model was applied to evaluate indoor PM2.5 concentrations in six urban districts of Beijing via an uncertainty analysis. The model was developed based on and applied to households using clean residential energy, and it would be interesting also important to evaluate it in households using solid fuels.

Security ambiguity and vulnerability in G2C eGovernance system: Empirical evidences from Indian higher education

The Higher Education Institutions (HEIs) in India enhanced dependency on Information Communication Technology (ICT) based on G2C eGovernance applications persistently raised apprehension regarding cyber-attacks and breach of security. Objectives:The present study assesses the status of ambiguity and vulnerability pertaining to security aspects of HEIs G2C eGovernance web portals. Methods:Five prominent central and state HEIs i.e. Malaviya National Institute of Technology - Jaipur (MNIT), National Institute of Technology - Kurukshetra (NITK), Guru Nanak Dev University -Amritsar (GNDU), Maharshi Dayanand University – Rohtak (MDU), and Bhagat Phool Singh Mahila Vishwavidyalaya – Sonipat (BPSMV) were included in the study and Grey Box penetration testing method through open-source software’s Whois.sc, Yougetsignal.com, Kali Linux, Builtwith.com, NMAP, and Google Hacking Database (GHDB), etc. along with social engineering testing through external penetration strategy was applied to assess the ambiguity and vulnerability of HEIs. Findings:The analysis revealed that login IDs and passwords related to web portals, eResources, networks, etc. are freely available and shared without any authorization which is a major cause of security breach. The vulnerability test depicted unencrypted communication between the HEIs portals and servers and the absence of well-articulated security and privacy. Novelty: The study exhibits the lenient view of HEIs administration towards security aspects of G2C eGovernance projects and the outcome would enable the HEIs of India to develop a comprehensive security policy for enriching and securing the G2C eGovernance System. Keywords: eGovernance; security; ambiguity; vulnerability; privacy policy; social engineering testing

Analysis of Deauthentication Attack on IEEE 802.11 Connectivity Based on IoT Technology Using External Penetration Test

The research aims to know the level of security of WiFi connectivity against deauthentication attacks on Internet of Things (IoT)-based devices. It is done through testing using an external penetration test method. The external penetration test simulates a real external attack without information about the target system and network given. The process starts from accessing the device through Internet or WiFi by the test target. At the same time, the attacker performs Denial-of-Service (DoS) attacks onWiFi. The attacker uses Arduino ESP8266 NodeMCU WiFi with Lua programming. To record WiFi activities, the researchers use CommView for WiFi V. 7.0, and the target is Internet Protocol (IP) camera device. The result shows that the communication of the test target with the gateway is lost, but the Media Access Control (MAC) of the test target is still registered at the gateway. Deauthentication attacks cause communication paralysis, and several changes occur, such as an increase in data rate, and change in frequency channel, Distribution System (DS) status, retry bits in frame management, and the sequence number.

Morpho-anatomical differences among mycoheterotrophic Afrothismia spp. (Thismiaceae) indicate an evolutionary progression towards improved mycorrhizal benefit

Achlorophyllous, mycoheterotrophic plants depend on their mycorrhizal fungi for 100% of their carbon supply. Hence, there is strong evolutionary pressure towards a well-organized functioning of the association from the plant’s perspective. Members of the mycoheterotrophic genus Afrothismia have evolved elaborate fungal colonization patterns allowing a sustained benefit from external fungal penetration events. On the basis of anatomical details of the root-shoot systems of A. korupensis and A. hydra, we elucidate an evolutionary progression between the comparatively simple mycorrhizal pattern in A. gesnerioides and the so far most complex mycorrhiza in A. saingei. We detected two major advancements: (1) two species, A. korupensis and A. saingei, use the fungus itself as energy storage, replacing starch depositions used by A. gesnerioides and A. hydra, and (2) the morphological complexity of hyphal forms in plant tissue compartments increases from A. gesnerioides to A. saingei. We discuss the omitting of starch metabolism as well as the morpho-anatomical differences as an evolutionary fine-tuning of the compartmented mycorrhizal organization in Afrothismia. Our results support the idea of a taxonomic distinction between Afrothismia and other Thismiaceae.

On Developing Techniques for Sharing Satellite Spectrum with Indoor Small Cells in 5G

In this paper, we present two spectrum sharing techniques for a multisystem, incorporating an integrated satellite-mobile system and an autonomous terrestrial-mobile system (iSMS/aTMS), namely orthogonal spectrum sharing (OSS) and non-orthogonal spectrum sharing (nOSS) techniques. aTMS consists of numerous small cells deployed in several buildings, and iSMS consists of a satellite station integrated with complementary ground component (CGC) stations deployed within buildings. By exploiting the high external wall penetration loss of a building, the iSMS spectrum is shared with small cells per building in OSS, and small cells per 3-dimensional (3D) cluster per building in nOSS. An interference management scheme, to avoid interference in apartments with collocated CGC stations and small cells, was developed and an optimal number of almost blank subframes (ABSs) per ABS pattern period (APP) was defined. System-level capacity, spectral efficiency, and energy efficiency performance metrics were derived. Furthermore, we present an algorithm for both OSS and nOSS techniques. With extensive simulation and numerical analysis, it is shown that the proposed nOSS significantly outperforms OSS in terms of spectral efficiency and energy efficiency, and both techniques can meet the expected spectral efficiency and energy efficiency requirements for the fifth-generation (5G) mobile networks.

Ex vivo investigation on internal tunnel approach/internal resin infiltration and external nanosilver-modified resin infiltration of proximal caries exceeding into dentin.

This ex vivo proof-of-concept study aimed to investigate the effect of nanosilver particles (AgNP) added to a conventional infiltrant resin (Icon) on external penetration into natural proximal enamel caries exceeding into dentin after internal tunnel preparation and internal infiltration. Carious lesions (ICDAS codes 2/3) of extracted human (pre-)molars revealing proximal caries radiographically exceeding into dentin (E2/D1 lesions) were preselected. Then, 48 of those specimens showing demineralized areas transcending the enamel-dentin border as assessed by means of near-infrared light transillumination (DIAGNOcam) were deproteinized (NaOCl, 5%). Using an internal tunnel approach, occlusal cavities central to the marginal ridge were prepared. Excavation of carious dentin, total etch procedure (H3PO4, 40%), and internal resin infiltration (FITC-labeled) followed, along with final restorations (flowable composite resin). Outer lesion surfaces were etched (HCl, 15%) prior to external infiltration (RITC-labeled). Group 1 (control; n = 24) used non-modified infiltrant, while an infiltrant/AgNP mixture (20 nm; 5.5 wt%) was used with experimental Group 2 (n = 24). Non-infiltrated pores of cut lesions were stained (Berberine), and specimens were analyzed using confocal laser scanning microscopy. Compared to the non-filled infiltrant, incorporation of AgNP had no effect on the resin's external penetration. Between the groups, no significant differences regarding internal or external infiltration could be detected, and non-infiltrated lesion areas did not differ significantly (p>0.109; t-test). The internal tunnel preparation in combination with both an internal resin infiltration and an additional external infiltration approach using a nanosilver-modified infiltrant resin leads to increased infiltrated lesion areas, thus occluding and adhesively stabilizing the porous volume of the demineralized enamel. While exerting antimicrobial effects by the nanosilver particles, this approach should have the potential as a viable treatment alternative for proximal lesions extending into dentin, thus avoiding the sacrifice of sound enamel, postponing the frequently inevitable restoration/re-restoration cycle of conventional proximal caries treatment, and improving dental health.

Mild Head Injury Patients; Correlation between admission Computed Tomography Brain Scan and outcome

Background: Traumatic injuries of brain is considered the damage of the brain which result from external force, like impact, deceleration, blast waves, rapid acceleration, and penetration by a projectile. Brain function is permanently or temporarily impaired and the damage of the structure could or could not be revealable with recent technology. Objectives: To assess post-traumatic CT scan brain changes to patients with mild head injuries in correlation to clinical sequelae. Patients and Methods: This prospective cohort study was conducted at Neurosurgery Department, Zigzag University Hospitals, on 75 patients of mild traumatic brain injury (mTBI) presented to emergency department at zagazig university hospital with mean age of 26.7 years, during the period from April 2018 to September 2018. Results: The most common CT finding in patients with mild head injury in our study was a skull fracture by 43% then contusion by32% and Epidural hemorrhage by 21.5% and least one was Subarachnoid hemorrhage by10.7% none of the participants in our current study had a subdural hemorrhage. percent of positive findings on CT scan was 9.3% and 2.6% need surgical intervention , the outcome of the patient was assessed by Glasgow outcome score (GOS) and most of the patient score was 5 which a good score. Conclusion: Patients with mild traumatic head injury with a presenting GCS score of 13 or 14 should undergo a CT scan examination and to be admitted for observation and management.

A Tactic for Architectural Exploitation of Indoor Small Cells for Dynamic Spectrum Sharing in 5G

This paper presents a tactic to realize numerous in-building small cell base station (SBS) architectures for dynamic spectrum sharing by varying the number of physical transceivers as well as the number, amount, and characteristics of operating spectrums per SBS. Each SBS architecture is defined as a Type and the spectrum sharing mechanism of each Type of architecture is detailed and mathematically analyzed to define existing dynamic spectrum sharing techniques suggested in the literature. The high external wall penetration loss of a building and the eICIC technique are exploited to manage co-channel interference generated due to sharing the spectrum of one system to another. System-level capacity, spectral efficiency, and energy efficiency performance metrics are derived for each SBS architecture to show the relative outperformance of one to another. It is found that, unlike energy efficiency (EE), the spectral efficiency (SE) response of an SBS architecture is directly affected by the channel characteristics as well as the number and amount of operating spectrum bands. However, the number of transceivers of an SBS does not have a noticeable impact on both SE and EE so long as the feature of an operating spectrum is not altered. Finally, we show that each Type of the proposed SBS architectures can achieve the prospective SE and EE requirements for fifth-generation (5G) mobile networks.

Countrywide Mobile Spectrum Sharing with Small Indoor Cells for Massive Spectral and Energy Efficiencies in 5G and Beyond Mobile Networks

In this paper, we propose a technique to share the licensed spectrums of all mobile network operators (MNOs) of a country with in-building small cells per MNO by exploiting the external wall penetration loss of a building and introducing the time-domain eICIC technique. The proposed technique considers allocating the dedicated spectrum Bop per MNO only its to outdoor macro UEs, whereas the total spectrum of all MNOs of the country Bco to its small cells indoor per building such that technically any small indoor cell of an MNO can have access to Bco instead of merely Bop assigned only to the MNO itself. We develop an interference management strategy as well as an algorithm for the proposed technique. System-level capacity, spectral efficiency, and energy efficiency performance metrics are derived, and a generic model for energy efficiency is presented. An optimal amount of small indoor cell density in terms of the number of buildings L carrying these small cells per MNO to trade-off the spectral efficiency and the energy efficiency is derived. With the system-level numerical and simulation results, we define an optimal value of L for a dense deployment of small indoor cells of an MNO and show that the proposed spectrum sharing technique can achieve massive indoor capacity, spectral efficiency, and energy efficiency for the MNO. Finally, we demonstrate that the proposed spectrum sharing technique could meet both the spectral efficiency and the energy efficiency requirements for 5G mobile networks for numerous traffic arrival rates to small indoor cells per building of an MNO.

269 Agent-based computational modeling of the human epidermis and applications

The ontogenesis and maintenance of human epidermis is well documented in the scientific literature. Under physiological conditions, processes such as epidermal cell proliferation, differentiation and eventual desquamation from the skin surface are coordinated to support epidermal homeostasis. We have developed an agent-based computational model of the human epidermis that recapitulates the biochemical and biomechanical aspects of the tissue physiology. Modeling is performed at the individual cell (“agent”) level and multiple agents are then allowed to follow their programming and interact with their neighbors. Although all programing is done at the cellular level, emerging properties of the system are manifested at the tissue level, such as dynamic steady state of the stratified epidermis, barrier to water loss as well as to external penetration of topical substances, steady state water and calcium profiles qualitative similar to the ones in the literature, etc. By appropriately adjusting the rate constants of the processes at the cellular level we have been able to achieve distinct tissue architectures corresponding to adult and infant epidermis. This approach allows us to perform experiments in silico by perturbing the system and monitoring its behavior, such as following complete removal of the Stratum Corneum. Moreover, the model was able to recapitulate clinical data of: a) the effects of a topical moisturizer, b) the dynamics of tissue penetration of a topically applied agent, c) skin barrier-related effects of topical treatment with a surfactant, and d) effects of a barrier-enhancing topical agent. In conclusion, computational modeling is a valuable tool for studying epidermal behavior and demonstrating product effects, which can be used to provide design guidelines for topical product development.

Ризик зникнення берези повислої в Житомирському Поліссі України

З’ясовано причини усихання березових насаджень у Житомирському Поліссі України. Акцентовано увагу на глибокій патології берези повислої, яка спричинена комплексом факторів і передусім пов’язана з бактеріальною етіологією. Встановлено, що мокра деревина у стовбурі беріз – бактеріального походження. Відібрано зразки деревини й ексудату для лабораторних досліджень із рослин, які мали яскраво виражені ознаки патології (тріщини, здуття). Експериментально доведено, що збудником бактеріозу берези повислої є фітопатогенна бактерія-полібіотроф Enterobacter nimipressuralis Carter, яка спричинює водянку хвойних і листяних лісових деревних рослин.
 Встановлено, що на ступінь всихання беріз дещо впливає склад насаджень – складні за формою і мішані за складом деревостани є стійкішими до бактеріозу. Поширеність бактеріальної водянки в березових насадженнях різних вікових груп зростає зі збільшенням їхнього віку і зниженням повноти. Відзначено неоднаковий ступінь ураження бактеріальною водянкою різних груп рослинних асоціацій: чорницевих, злакових, зеленомохових та вересових.
 Під час обстеження стовбурів модельних дерев виявлено закономірність висотного розташування осередків ураження. Наведено дані щодо характеру типу ураження і щільності розташування виразок на стовбурі, описано видовий склад і рівень домінування рогохвостів, котрі екологічно та трофічно пов’язані з березою повислою.

690 In vivo assessment of cleanser mildness by confocal raman microspectroscopy

Skin cleansers contain surfactants, which may compromise the integrity of skin barrier to the penetration of external aggressors, resulting in skin irritation. Assessing cleanser mildness on skin is typically done by clinical evaluation and measurement of alterations in trans epidermal water loss (TEWL) following exaggerated patch test or exaggerated wash test protocols. These methods are partly subjective and often with variable results. Previously, we demonstrated that the effects of a relatively harsh surfactant (0.1% sodium lauryl sulfate) on skin barrier can be objectively assessed by measuring the concentration profile of a marker with a known safety profile (caffeine) that penetrated into the skin, using in vivo confocal Raman microspectroscopy (CRM). In the present work, we demonstrate that this method can be used to discriminate between different cleanser formulations according to their effect on skin barrier to external penetration. The results of the caffeine penetration method are compared with the more commonly used exaggerated patch and exaggerated arm wash tests. The ordered rating of the product mildness of the caffeine penetration method agrees with the results of the exaggerated tests, confirming the validity of the method. In conclusion, the caffeine penetration test objectively evaluates the effects of topical cleansers on skin barrier to external penetration and can be used to assess cleanser mildness.

Quantitative measurement of the influence of degree of saturation on ion penetration in cement paste by using X-ray imaging

The external penetration of ions into concrete plays an important role in long-term durability of concrete structures. In addition, the degree of saturation (DoS) of the paste has a large impact on rate and mechanisms of fluid penetration into concrete. There is little knowledge of the dynamic process of fluid penetration into these materials because few experimental techniques are able to give quantitative spatial measurements of the fluid movement without damaging the sample. This paper uses laboratory transmission X-ray microscopy (TXM) to investigate the in-situ penetration of an iodide based tracer into cement paste with water-to-cement ratio of 0.40 conditioned at four different relative humidities (RH). This technique can non-destructively image the distribution of the dissolved ions at 8.8μm resolution in minutes. In addition, micro X-ray fluorescence (µXRF) imaging and conventional gravimetric measurements were used to compare I and Cl penetration rate and validate the results from TXM. Mathematical models have been proposed to account for ion penetration in partially-saturated samples. The results show that samples that were ponded for two days after being conditioned in 35% and 70% RHs (DoS of 40.8% (±0.1%) and 68.8% (±0.5%) respectively) show a 40× and 10× increase respectively in the penetration coefficient over the saturated sample. Furthermore, important insights about combined ion transport mechanisms have been observed from concentration profiles by TXM.

Using X-ray imaging to investigate in-situ ion diffusion in cementitious materials

The external penetration of ions into cementitious materials plays an important role in long-term durability of concrete structures. Current test methods to study bulk diffusion of ions in cement-based materials are typically destructive, time consuming and labor intensive. This research work uses laboratory transmission X-ray microscopy (TXM) and X-ray computed microtomography (μCT) to image iodide diffusion in cement paste. These techniques can non-destructively image the distribution of the dissolved ions at 8.8μm resolution in minutes with a 2D analysis and a few hours for 3D. This method does not aim to measure the size of the pores, instead it aims to image the movement of the fluid through the pores by imaging an electron dense tracer with similar behavior as chloride ions. The tests were completed on cement paste mixtures with water-to-cement ratios (w/c) of 0.35, 0.40, and 0.45. The findings were validated with micro X-ray fluorescence (μXRF) imaging. Iodide and chloride diffusivity is also compared for paste samples with w/c of 0.40 and shown to provide comparable results. Results are also presented of 3D ion diffusion and void filling at high degrees of saturation.

Semipermeability of concrete for hazardous waste containment

Low-level waste is stored in multilayer, overlapping barrier systems for long-term containment, which serve as the primary barrier against leakage. Reinforced concrete is typically used as the container material for radioactive wastes, making the material properties paramount for contaminant control. Strength, density, corrosion resistance and permeability are regulated. This study examined the physico-chemical properties of high-density, lower-permeability concrete for potential to hyperfiltrate chloride solutions (185 and 345 parts per million) under relatively low hydraulic head, similar to encasement. Four hyperfiltration experiments were conducted on intact concrete discs, two experiments for each solution at hydrostatic heads of 0·5 and 1·0 m. Chloride concentrations measured within the experimental cells showed an increase ranging from 126% to 152%. Reflection coefficients ranged from 0·15 to 0·19, suggesting that low-permeability concrete discs exhibit measurable solute rejection capabilities. External chloride penetration may initially be hampered. However, once steady state had been established and salt penetrated at a fixed rate, the concentration polarization layer (CPL) provided a source for continued penetration. With the CPL adjacent to a container, corrosion may accelerate in the reinforcing rebar due to the high chloride concentration and chemical gradient within the pores. The application of electro-osmotic pulses can reverse chloride intrusion.