Nano-scale evaluation of moisture damage in asphalt

Moisture damage is one of the major problems of asphalt pavements in United States. The moisture damage problem in asphalt has been studied for decades; still it remains an unsolved problem. Traditional macro-scale tests and methods failed to describe how and what factors affect moisture damage because moisture damage in asphalt is related to asphalt chemistry and adhesion characteristics, which are below micron scale phenomena. To this end, asphalt chemistry and adhesion values are studied at nano-scale to understand moisture damage in this study. Nano-scale measurements are conducted using an Atomic Force Microscope (AFM) in the laboratory. In an AFM test, adhesion forces of dry and wet asphalt samples are measured by probing the sample surface with AFM tips. Nano-scale pull-off force or adhesion between sample molecules and tip molecules are measured. To facilitate the study of asphalt chemistry, AFM tips are modified using chemical functional groups such as carboxyl (-COOH), hydroxyl (-OH), ammin (-NH3) and methyl (-CH3), representing the chemistry of asphalt binder. Thus functionalized tips facilitate the measurement of adhesion within the asphalt binder. In addition, silicon nitride (Si3N4) tips are used. Silicon nitride resembles aggregate molecules (e.g. silica aggregate) that are used to produce asphalt concrete or pavements. Thus adhesion value measured using a silicon nitride tip can be considered as the adhesion value of asphalt-aggregate interface. It is shown in this study that the adhesion within the asphalt binder varies depending on the chemistry of asphalt. AFM testing on asphalt is non-trivial and very challenging as AFM tips stick to the asphalt surface due to the viscous and soft nature of asphalt binder. AFM testing also requires smooth surface of a test sample. This study has developed a methodology for asphalt sample preparation for AFM testing. Simply, pouring asphalt binder on a glass substrate and melting to free flow and then cooling it generates an AFM asphalt sample with a root mean square surface roughness below 10 nm. Such sample surface is smooth enough for AFM testing. Through trial and error, this study has calibrated a set of AFM testing parameters that are suitable for successful adhesion measurement in asphalt binder. In all cases, a set of AFM samples are tested under dry condition, and a set of identical samples are tested after wet conditioning. Polymer is almost an essential component of asphalt binders now-a-days. However it is not known whether polymer modification helps reduce moisture damage potential of asphalt. Therefore, both base binder and polymer modified asphalt binder are characterized herein using AFM. Two common polymers Styrene-Butadyne (SB) and Styrene-Butadyne-Styrene (SBS) are used to modify the base asphalt. The goal is to examine whether polymer modification helps reduce moisture damage at nano-scale. In addition to polymer, a chemical modifier known as Elvaloy is included in this study to examine whether Elvaloy is more effective than polymer in regards to moisture damage. It is shown that both base and modified asphalt binders are vulnerable to moisture damage to some degree. However, base binder is the most susceptible to moisture damage among all the binders. It is evident that the SB polymer modification of asphalt is good for interface adhesion, whereas the SBS polymer modification is good for achieving higher adhesion within the asphalt binder. Antistripping agents are commonly used to reduce moisture damage potential of an asphalt binder. A number of antistripping agents are available in the market. However, it is not know which antistripping works better than others. To examine, five common antistripping agents such as lime, klingbeta, wetfix, morlife and unichem are considered for AFM testing in this study. It is evident from this study that moisture damage occurs in asphalt binder having an antistripping agent. Hydrated lime provides higher moisture damage resistance to asphalt binders that the liquid antistripping agents such as morlife, unichem, klingbeta, and wetfix. Statistical analysis of the adhesion test results is performed. Based on Pearsons p-value (significance test), it is concluded that the adhesion value measure by an AFM varies with the type and amount of antistripping agent present in an asphalt sample. Finally, an attempt is made to correlate nano-scale adhesion value of an asphalt binder to macro-scale strength value representing moisture damage. Only polymer modified binders are considered for examining such correlations. Macro-scale indirect tension tests are conducted on wet and dry asphalt concrete samples. A good correlation exists between the macro-scale indirect tensile strength ratio, and nano-scale adhesion ratio of wet and dry samples.\u2

Use of a New Transportation Algorithm for Profit Maximization

A transportation calculation is advanced, and it makes it possible to be able to effectively plan the assets with the end goal of augmenting the benefit of an assembling organization. The distribution indicators (DI) have been resolved from the distinction of the bigger unit profit and the average value of total unit profit of each row and column. Also, the area of the fundamental cells has been resolved as the biggest entrance of the transportation table (TT) along the biggest DI. The most extreme benefit given by this calculation is closer to the other benefit. The strategy, however, is represented with numerical examples to legitimize its proficiency

Compressive behavior of perlite/sodium silicate composite foam modified by boric acid

In this work lightweight expanded perlite/sodium silicate composite foams were manufactured with varying quantities of boric acid (BA) 0-2.88 wt.%. The composites were characterized for density, compressive strength (CS), compressive modulus (CM), and energy absorption (EA) up to 50% strain. The compression tests were also conducted at various crosshead speeds to evaluate the strain rate dependency of the foams. The hygroscopic tests were done to evaluate water absorption properties and investigate the effects of water absorption on the compressive properties of the foams. The CS, CM, and EA of the foams increased for a boric acid content of 0.74 wt.%, but further addition of BA caused a gradual decrease in these characteristics. The range of sp. CS (3.80-5.93 MPa/(g/cm3)) achieved were found to be well compatible with the values of building materials in the literature. The foams appeared to be sensitive to the strain rate in compression, causing variations in the compressive properties as well as the trends of stress-strain curves. Furthermore, the addition of BA in the composite reduced water absorption up to a BA content of 1.46 wt.%. The compressive properties were also highly influenced by the hygrometric test

A Novel msDNA (Multicopy Single-Stranded DNA) Strain Present in Yersinia frederiksenii ATCC 33641 Contig01029 Enteropathogenic Bacteria with the Genomic Analysis of It's Retron

Retron is a retroelement that encodes msDNA (multicopy single-stranded DNA) which was significantly found mainly in Gram-negative pathogenic bacteria. We screened Yersinia frederiksenii ATCC 33641 contig01029 for the presence of retroelement by using bioinformatics tools and characterized a novel retron-Yf79 on the chromosome that encodes msDNA-Yf79. In this study, we perceived that, the codon usage of retron-Yf79 were noteworthy different from those of the Y. frederiksenii genome. It demonstrates that, the retron-Yf79 was a foreign DNA element and integrated into this organism genome during their evolution. In addition to this, we have observed a transposase gene which is located just downstream of retron-Yf79. So, the enzyme might be responsible for the transposition of this novel retron element

Specific Growth Rate (SGR) in Different Stages of Tilapia (Oreochromis niloticus) Production Cycle in Cemented Tank Based Semi-Intensive Aquaculture System

Traditional assessment of specific growth rate (SGR) using the data of the beginning and the end of aquaculture production cycle, avoiding intermediary data, is criticized as misleading way by the scholars. However, by knowing SGR in different stages of fish growth, the utilization of feed by fish can be well known. The study was conducted with aim to assess SGR of Tilapia in six concrete tanks for 90 days from 8th May to 10th August, 2017. Tilapia (Oreochromis niloticus) fry was released at the rate of 4 fry per tank equivalent to the stocking density of 160 fishes/decimal as of the semi-intensive aquaculture system. Sinking and floating feeds were used for feeding the fish in T1 and T2, respectively with three replications for each treatment. During the experimental period, feed was given at the rate of 20%, 15% and 10% of the body weight in 1st, 2nd and 3rd month, respectively. Moreover, aeration facilities were installed for 24 hours using air stone aerator. The weight of fish was recorded using digital balance in 3 days interval to measure SGR. The water quality parameters i.e., temperature and dissolved oxygen (DO) were recorded twice daily. The weight gains of fish were 49.90±2.40 g and 63.12±4.97g for T1 and T2, respectively. The mean percent weight gain of Tilapia was higher in T2 (747±0.00 g) than T1 (253.51±0.00 g). Feed conversion ratio (FCR) in T1 and T2 were 1.70±0.07 and 1.90±0.20, respectively. Considering the data at the beginning and the end of the production cycle, the SGR (% per day) of Tilapia in T1 and T2 were 6.27±3.27 and 6.26±3.83, respectively. The SGR for floating feed was higher at the initial stage of production cycle and lower in the later stages. For sinking feed, SGR was almost static from the beginning to the end. The higher FCR in T2 correlated with the lower SGR in the later stage of the culture period. Higher total production was obtained in T2 (830.96 g) than T1 (610 g) with 100% survival in both treatments. Therefore, determining SGR in a specific interval, at least 15 days interval, might be the efficient feeding practice of Tilapia farmers.&nbsp

Use of Biomechanical Motion Analysis and Pelvic Surgery Simulator for the Prevention of Surgical Errors in Mid-urethral Sling Anti-Incontinence Surgery

Dissertation advisors: Antonis P. Stylanou and Majid Bani-YaghoubVitaIncludes bibliographical references (pages 81-93)Dissertation (Ph.D.)--Department of Civil and Mechanical Engineering, Department of Mathematics and Statistics. University of Missouri--Kansas City, 2023More than 200 million surgeries are performed annually worldwide in which preventable complications occur in up to 22 percent of these surgeries, with permanent disability rates between 0.4 - 0.8 percent. Resident surgeons are more likely to commit surgical errors as they start their surgical career with less mastery and surgical skills. Yet other than close supervision in the operating room, there is no accepted way to teach a young surgeon how to prevent surgical errors. This work discusses a method that was focused on identifying and modeling individual surgical errors to improve the training of individual surgeons and complement systems approaches, and thus lead to effective error prevention. This technique involved a combination of virtual and physical anatomic models, simulation of surgical injury, and kinematics of both surgeon and surgical instrument to identify, model and describe surgical errors quantitatively. This study targets a complex, high-risk step of the Midurethral Sling surgery which is highly effective in reducing stress urinary incontinence. This surgery involves the insertion of a strip of mesh underneath the urethra and the surgeon is tasked with blindly guiding a sharp steel trocar behind the pubic symphysis and past the bladder, bowel, and major blood vessels. If the trocar is not guided properly through its passage (from vagina to the suprapubic skin), it can lead to several injuries, such as injury to the bladder or urethra (4.9%), injury to the bowel (0.1%), and injury to external iliac vessels (2.0%). This work effectively integrates the concepts and theories from both biomechanical engineering and medicine (surgery), including MRI segmentation, development of subject-specific virtual and physical models, motion capture technology, testing cadaveric specimens, multi-body modeling, musculoskeletal modeling, and simulation. Three MUS physical pelvic floor models were developed by segmenting the pelvic bones and organs from MR images of three patients with stress urinary incontinence. Segmented pelvic bone structure was 3D printed and the open space between the bone was filled with thermoballistic gel to provide the haptic feedback associated with soft tissue during the retropubic trocar passage. Vital injuries during the Midurethral sling Surgery (MUS) can be avoided by maintaining constant contact between the trocar tip and pubic bone, yet this is challenging for a teaching surgeon to monitor during this blind procedure. A force-sensing trocar was developed by modifying the retropubic trocar with a load cell which can distinguish on-bone and off-bone movement during the procedure. Two expert and three novice surgeons performed retropubic trocar passage on the MUS physical pelvic floor model using the modified trocar. Bio-fidelity of the MUS physical model was assessed by analyzing the force variables in the expert passages performed on a thiel-embalmed cadaver and the MUS physical model, using this force-sensing trocar. Test-retest analysis was conducted to analyze the force-sensitivity of this proposed model-trocar system using trocar passages performed on the MUS physical model two weeks apart. Post-hoc analyses were performed to compare the expert vs. novice performance on the physical model. Three expert and three novice surgeons participated in the kinematic study where both the surgical instrument (trocar) and surgeon body movements were tracked. Both the surgical instrument and surgeon body were equipped with retroreflective markers to facilitate the motion tracking during this procedure, using OptiTrack Flex 13 motion capture system. Multibody kinematic models were developed in MSC ADAMS to analyze the surgical instrument kinematics. Musculoskeletal models were developed using OpenSim to analyze the surgeon body kinematics during the retropubic trocar passage. Simulated trocar passage (from the vaginal incision point to the exit point at rectus fascia) was separated into 4 stages for the purpose of analysis. Mixed model analysis was used to analyze the trocar trajectories, temporal data, and surgeon upper extremity kinematic variables obtained from the retropubic passages performed by each participant. Paired sample t-tests revealed no statistically significant differences on the outcome force variables between trocar passages performed on cadaver and MUS physical model, suggesting adequate bio-fidelity of this physical pelvic model. Test-retest analysis also exhibited no significant difference between the testing sessions on any of the outcome variables. Independent sample t-tests revealed significantly larger amplitude of maximum force development, larger maximum rate of force development and shorter time to reach the maximum force in the expert participants than the novices. Simulated trocar passages in the multibody models revealed that the experts completed 27 error-free passages and 18 bladder error passages (40%). Novices completed 18 error-free passages, 4 bladder error passages and 23 anterior error passages, resulting in an overall error rate of 60%. Mixed model analysis revealed that the trocar tip trajectories were significantly different between the error free passages and the bladder error passages in the anterior-posterior and caudal-cephalad directions for both left and right shoulder passages. The incidence of the anterior error passages was significantly higher in the novices for both left and right directions. Experts had significantly longer mean trial duration and path length, compared to the novices. Mixed model analysis was also used to analyze the total trocar path variation which indicated that 48% of variation was attributed to the novices, where only 14% path variation was attributed to the experts. Mixed model analysis of the surgeon body kinematic variables revealed that the bladder contact trials were significantly associated with higher starting wrist dorsiflexion, less final elbow flexion and greater range of motion in both wrist dorsiflexion and elbow flexion at stage 3. Anterior versus posterior passage analysis performed on stage 1 indicated this incidence is significantly associated with less elbow flexion. Expert versus novice analysis revealed that novices had significantly higher range of motion in elbow flexion, but less range of motion in wrist dorsiflexion and arm pronation during stage 1, compared to the experts. However, stage 2 exhibited less range of motion with arm pronation and less range of motion with shoulder flexion in the novices. This study suggests high test-retest reliability and adequate bio-fidelity of the modified trocar used on our MUS 3D surgery simulator. This innovative trocar can be used both in surgical simulation and in the operating room to help the novice stay on the bone, and to help the attending monitor safe surgery. Kinematic analysis of the surgical instrument movement indicated that the novice passages were predominantly anterior to the pubic bone. In addition, significantly higher trocar path variation in the novices suggests that they were not able to follow a consistent trocar path between trials. Surgeon upper extremity kinematics indicate that expert participants exhibited more consistency with the distal joints (wrist and forearm), while the novices mostly focused on the proximal joints (elbow). Monitoring the temporal and kinematic characteristics of trocar, and the surgeon body kinematics provides useful insights into the types of errors occurred during retropubic trocar passage and has the potential to provide insight into proper education of surgical trainees. This is the first study that incorporated motion capture technology with a high-fidelity 3D pelvic surgery simulator to track the surgical instrument and surgeon body movements during the MUS procedure. Methods used in this study has the potential to be used for monitoring the sling placement in the operating room, accelerate the learning experience of novice through insights from surgeon kinematics, thus lead to effective error prevention in the midurethral sling surgery.Introduction -- Methods -- Results & Analysis -- Discussion -- Conclusio

Virtual Pelvic Surgery Simulator for the Prevention of Surgical Errors

Title from PDF of title page viewed June 12, 2019Thesis advisor: Antonis P. StylianouVitaIncludes bibliographical references (pages 60-62)Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2019Recent data suggests that over 200 million surgeries are performed annually worldwide and about 3 to 22% of these surgeries involve some sort of complications. Surgical errors can be caused by both technical errors and cognitive errors which may happen to even an experienced surgeon. Resident surgeons are more prone to surgical errors as they start their surgical career with less experience and skills. In order to quantify the surgical errors and accelerate the learning experience of surgeons, a novel method has been proposed that can identify, model and describe surgical errors by using biomechanical motion analysis and a high-fidelity 3-D surgery simulator. This analysis has been done for a complex, common and high-risk surgery, the midurethral sling (MUS) procedure for stress urinary incontinence. The experimental protocol allowed for monitoring of the surgeon’s full body kinematics during the procedure and accurate tracking of the trocar inside the body. Surgeon kinematics and position of the trocar relative to anatomical structures were tracked for both successful (continuous contact with the pubis) and error trials (lateral deviation and cephalad deviation). The kinematics of the wrist, elbow, and shoulder joints demonstrate major differences between the three different passage conditions. Cephalad deviation of the trocar entered the peritoneal cavity, but during lateral deviation, trocar remains within the anterior side of the pelvic bone without making any contact with the external iliac vein. Off plane rotations of the shoulder, elbow and wrist joints, i.e. abduction-adduction, and internal-external rotations, incurred large errors due to the marker set used in the experiment. The model demonstrated good fidelity except for gel thickness and transparency. Based on the expert surgeon, the physical model replicated the feeling of performing the procedure on a live subject. Differences in the elbow, wrist and shoulder joint kinematics between the three different passage conditions indicate that it is possible to identify errors based on kinematics. Since the kinematics between the different trials seem to be different, there is potential in training novice surgeons on proper kinematics to ensure successful passages of the trocar.Introduction -- Literature review -- Background -- Methods -- Results -- Discussion -- Appendi

State-of-the-Art Review on Utilization of Fly Ash in Pavement Structures

The use of fly ash in construction has been on the rise, yet its application in pavement construction remains relatively underexplored. This study addresses this gap by critically reviewing 70 years of research on fly ash usage in pavement engineering, offering valuable recommendations. Class 'C' fly ash is employed for soil stabilization, while class 'F' is used in concrete. In both flexible (asphalt) and rigid (concrete) pavements, fly ash primarily functions as a filler material. Fine ash, owing to its fineness, enhances asphalt concrete by reducing void ratios and water sensitivity, as well as easing subgrade compaction while increasing compressive strength. Incorporating fly ash into Hot Mix Asphalt (HMA) enhances resistance to cracking and oxidative ageing. Adding fly ash (up to 25%) significantly boosts soil failure stress and strain values by 106% and 50%, respectively, while a combination of 8% lime and 18% fly ash yields maximum shear strength. A modest amount of lime (1-2%) mixed with 10% fly ash achieves a maximum dry density of 1.98 gm/cm3 at an optimal water content of 12.62%. Additional testing by researchers corroborates and validates the findings of this literature review

Modelling of Asphalt's Adhesive Behaviour Using Classification and Regression Tree (CART) Analysis

The modification by polymers and nanomaterials can significantly improve different properties of asphalt. However, during the service life, the oxidation affects the constituents of modified asphalt and subsequently results in deviation from the desired properties. One of the important properties affected due to oxidation is the adhesive properties of modified asphalt. In this study, the adhesive properties of asphalt modified with the polymers (styrene-butadiene-styrene and styrene-butadiene) and carbon nanotubes were investigated. Asphalt samples were aged in the laboratory by simulating the field conditions, and then adhesive properties were evaluated by different tips of atomic force microscopy (AFM) following the existing functional group in asphalt. Finally, a predictive modelling and machine learning technique called the classification and regression tree (CART) was used to predict the adhesive properties of modified asphalt subjected to oxidation. The parameters that affect the behaviour of asphalt have been used to predict the results using the CART. The results obtained from CART analysis were also compared with those from the regression model. It was observed that the CART analysis shows more explanatory relationships between different variables. The model can predict accurately the adhesive properties of modified asphalts considering the real field oxidation and chemistry of asphalt at a nanoscale.publication of this article was funded by the Qatar National LibraryScopu