Search results for: sound and shape production
Commenced in January 2007
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Paper Count: 9997

Search results for: sound and shape production

4687 Stable Time Reversed Integration of the Navier-Stokes Equation Using an Adjoint Gradient Method

Authors: Jurriaan Gillissen

Abstract:

This work is concerned with stabilizing the numerical integration of the Navier-Stokes equation (NSE), backwards in time. Applications involve the detection of sources of, e.g., sound, heat, and pollutants. Stable reverse numerical integration of parabolic differential equations is also relevant for image de-blurring. While the literature addresses the reverse integration problem of the advection-diffusion equation, the problem of numerical reverse integration of the NSE has, to our knowledge, not yet been addressed. Owing to the presence of viscosity, the NSE is irreversible, i.e., when going backwards in time, the fluid behaves, as if it had a negative viscosity. As an effect, perturbations from the perfect solution, due to round off errors or discretization errors, grow exponentially in time, and reverse integration of the NSE is inherently unstable, regardless of using an implicit time integration scheme. Consequently, some sort of filtering is required, in order to achieve a stable, numerical, reversed integration. The challenge is to find a filter with a minimal adverse affect on the accuracy of the reversed integration. In the present work, we explore an adjoint gradient method (AGM) to achieve this goal, and we apply this technique to two-dimensional (2D), decaying turbulence. The AGM solves for the initial velocity field u0 at t = 0, that, when integrated forward in time, produces a final velocity field u1 at t = 1, that is as close as is feasibly possible to some specified target field v1. The initial field u0 defines a minimum of a cost-functional J, that measures the distance between u1 and v1. In the minimization procedure, the u0 is updated iteratively along the gradient of J w.r.t. u0, where the gradient is obtained by transporting J backwards in time from t = 1 to t = 0, using the adjoint NSE. The AGM thus effectively replaces the backward integration by multiple forward and backward adjoint integrations. Since the viscosity is negative in the adjoint NSE, each step of the AGM is numerically stable. Nevertheless, when applied to turbulence, the AGM develops instabilities, which limit the backward integration to small times. This is due to the exponential divergence of phase space trajectories in turbulent flow, which produces a multitude of local minima in J, when the integration time is large. As an effect, the AGM may select unphysical, noisy initial conditions. In order to improve this situation, we propose two remedies. First, we replace the integration by a sequence of smaller integrations, i.e., we divide the integration time into segments, where in each segment the target field v1 is taken as the initial field u0 from the previous segment. Second, we add an additional term (regularizer) to J, which is proportional to a high-order Laplacian of u0, and which dampens the gradients of u0. We show that suitable values for the segment size and for the regularizer, allow a stable reverse integration of 2D decaying turbulence, with accurate results for more then O(10) turbulent, integral time scales.

Keywords: time reversed integration, parabolic differential equations, adjoint gradient method, two dimensional turbulence

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4686 Complicated Corneal Ulceration in Cats: Clinical Diagnosis and Surgical Management of 80 Cases

Authors: Khaled M. Ali, Ayman A. Mostafa, Soliman M. Soliman

Abstract:

Objectives: To describe the most common clinical and endoscopic findings associated with complicated corneal ulcers in cats, and to determine the short-term outcomes after surgical treatment of these cats. Animals Eighteen client-owned cats of different breeds (52 females and 28 males), ranging in age from 3 months to 6 years, with corneal ulcers. Procedures: Cats were clinically evaluated to initially determine the concurrent corneal abnormalities. Endoscopic examination was performed to determine the anterior and posterior segments abnormalities. Superficial and deep stromal ulcers were treated using conjunctival flap. Corneal sequestrum was treated by partial keratectomy and conjunctival flap. Anterior synechia was treated via peripheral iridectomy and separation of the adhesion between the iris and the inner cornea. Symblepharon was treated by removal of the adhered conjunctival membrane from the cornea. Incurable endophthalmitis was treated surgically by extirpation. Short-term outcomes after surgical managements of selected corneal abnormalities were then assessed clinically and endoscopically. Results: Deep stromal ulcer with descemetocele, endophthalmitis, symblepharon, corneal sequestration and anterior synechia with secondary glaucoma and corneal scarring were the most common complications of corneal ulcer. FHV-1 was a common etiologic factor of corneal ulceration. Persistent corneal scars of varying shape and size developed in cats with deep stromal ulcer, anterior synechia, and corneal sequestration. Conclusions: Domestic shorthaired and Persian cats were the most predisposed breeds to FHV-1 infection and subsequent corneal ulceration. Immediate management of patients with corneal ulcer would prevent serious complications. No age or sex predisposition to complicated corneal ulceration in cats.

Keywords: cats, complicated corneal ulceration, clinical, endoscopic diagnosis, FHV-1

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4685 Corporate Law and Its View Point of Locking in Capital

Authors: Saad Saeed Althiabi

Abstract:

This paper discusses the corporate positioning and how it became popular as a way to systematize production because of the unique manner in which incorporation legalized organizers to secure financial capital through locking it in. The power to lock in capital comes from the fact that a corporate exists as a separate legal entity, whose survival and governance are separated from any of its participants. The law essentially creates a different legal person when a corporation is created. Although this idea has been played down in the legal learning of the last decades in favor of the view that a corporation is purely something through which natural persons interrelate, recent legal research has begun to reassess the importance of entity status. Entity status, under the law and the related separation of governance from input of financial capital through the configuration of a corporation, sanctioned corporate participants to do somewhat more than connect in a series of business transactions.

Keywords: corporate law, entity status, locking in capital, financial capital

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4684 Diagnosis Of Static, Dynamic, And Mixed Eccentricity In Line Start Permanent Magnet Synchronous Motor By Using FEM

Authors: Mohamed Moustafa Mahmoud Sedky

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In line start permanent magnet synchronous motor, eccentricity is a common fault that can make it necessary to remove the motor from the production line. However, because the motor may be inaccessible, diagnosing the fault is not easy. This paper presents an FEM that identifies different models, static eccentricity, dynamic eccentricity, and mixed eccentricity, at no load and full load. The method overcomes the difficulty of applying FEMs to transient behavior. It simulates motor speed, torque and flux density distribution along the air gap for SE, DE, and ME. This paper represents the various effects of different eccentricities types on the transient performance.

Keywords: line start permanent magnet, synchronous machine, static eccentricity, dynamic eccentricity, mixed eccentricity

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4683 The Role of Branding for Success in the Georgian Tea Market

Authors: Maia Seturi, Tamari Todua

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Economic growth is seen as the increase in the production capacity of a country. It enables a country to produce more and more material wealth and social benefits. Today, the success of any product on the market is closely related to the issue of branding. The brand is a source of information for a user/consumer, which helps to simplify the choice of goods and reduce consumer risk. The paper studies the role of branding in order to promote Georgian tea brands. The main focus of the research is directed to consumer attitudes regarding Georgian tea brands. The methodology of the paper is based on marketing research. The findings study revealed that the majority of consumers prefer foreign tea brands. The final part of the article presents the main recommendations.

Keywords: marketing research, customer behavior, brand, successful brand

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4682 Effects of Temperature and the Use of Bacteriocins on Cross-Contamination from Animal Source Food Processing: A Mathematical Model

Authors: Benjamin Castillo, Luis Pastenes, Fernando Cerdova

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The contamination of food by microbial agents is a common problem in the industry, especially regarding the elaboration of animal source products. Incorrect manipulation of the machinery or on the raw materials can cause a decrease in production or an epidemiological outbreak due to intoxication. In order to improve food product quality, different methods have been used to reduce or, at least, to slow down the growth of the pathogens, especially deteriorated, infectious or toxigenic bacteria. These methods are usually carried out under low temperatures and short processing time (abiotic agents), along with the application of antibacterial substances, such as bacteriocins (biotic agents). This, in a controlled and efficient way that fulfills the purpose of bacterial control without damaging the final product. Therefore, the objective of the present study is to design a secondary mathematical model that allows the prediction of both the biotic and abiotic factor impact associated with animal source food processing. In order to accomplish this objective, the authors propose a three-dimensional differential equation model, whose components are: bacterial growth, release, production and artificial incorporation of bacteriocins and changes in pH levels of the medium. These three dimensions are constantly being influenced by the temperature of the medium. Secondly, this model adapts to an idealized situation of cross-contamination animal source food processing, with the study agents being both the animal product and the contact surface. Thirdly, the stochastic simulations and the parametric sensibility analysis are compared with referential data. The main results obtained from the analysis and simulations of the mathematical model were to discover that, although bacterial growth can be stopped in lower temperatures, even lower ones are needed to eradicate it. However, this can be not only expensive, but counterproductive as well in terms of the quality of the raw materials and, on the other hand, higher temperatures accelerate bacterial growth. In other aspects, the use and efficiency of bacteriocins are an effective alternative in the short and medium terms. Moreover, an indicator of bacterial growth is a low-level pH, since lots of deteriorating bacteria are lactic acids. Lastly, the processing times are a secondary agent of concern when the rest of the aforementioned agents are under control. Our main conclusion is that when acclimating a mathematical model within the context of the industrial process, it can generate new tools that predict bacterial contamination, the impact of bacterial inhibition, and processing method times. In addition, the mathematical modeling proposed logistic input of broad application, which can be replicated on non-meat food products, other pathogens or even on contamination by crossed contact of allergen foods.

Keywords: bacteriocins, cross-contamination, mathematical model, temperature

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4681 Learning from TikTok Food Pranks to Promote Food Saving Among Adolescents

Authors: Xuan (Iris) Li, Jenny Zhengye Hou, Greg Hearn

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Food waste is a global issue, with an estimated 30% to 50% of food created never being consumed. Therefore, it is vital to reduce food waste and convert wasted food into recyclable outputs. TikTok provides a simple way of creating and duetting videos in just a few steps by using templates with the same sound/vision/caption effects to produce personalized content – this is called a duet, which is revealing to study the impact of TikTok on wasting more food or saving food. The research focuses on examining food-related content on TikTok, with particular attention paid to two distinct themes, food waste pranks and food-saving practices, to understand the potential impacts of these themes on adolescents and their attitudes toward sustainable food consumption practices. Specifically, the analysis explores how TikTok content related to food waste and/or food saving may contribute to the normalization and promotion of either positive or negative food behaviours among young viewers. The research employed content analysis and semi-structured interviews to understand what factors contribute to the difference in popularity between food pranks and food-saving videos and insights from the former can be applied to the latter to increase their communication effectiveness. The first category of food content on TikTok under examination pertains to food waste, including videos featuring pranks and mukbang. These forms of content have the potential to normalize or even encourage food waste behaviours among adolescents, exacerbating the already significant food waste problem. The second category of TikTok food content under examination relates to food saving, for example, videos teaching viewers how to maximize the use of food to reduce waste. This type of content can potentially empower adolescents to act against food waste and foster positive and sustainable food practices in their communities. The initial findings of the study suggest that TikTok content related to pranks appears to be more popular among viewers than content focused on teaching people how to save food. Additionally, these types of videos are gaining fans at a faster rate than content promoting more sustainable food practices. However, we argue there is a great potential for social media platforms like TikTok to play an educative role in promoting positive behaviour change among young people by sharing engaging content suitable to target audiences. This research serves as the first to investigate the potential utility of TikTok in food waste reduction and underscores the important role social media platforms can play in promoting sustainable food practices. The findings will help governments, organizations, and communities promote tailored and effective interventions to reduce food waste and help achieve the United Nations’ sustainable development goal of halving food waste by 2030.

Keywords: food waste reduction, behaviour, social media, TikTok, adolescents

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4680 Practical Modelling of RC Structural Walls under Monotonic and Cyclic Loading

Authors: Reza E. Sedgh, Rajesh P. Dhakal

Abstract:

Shear walls have been used extensively as the main lateral force resisting systems in multi-storey buildings. The recent development in performance based design urges practicing engineers to conduct nonlinear static or dynamic analysis to evaluate seismic performance of multi-storey shear wall buildings by employing distinct analytical models suggested in the literature. For practical purpose, application of macroscopic models to simulate the global and local nonlinear behavior of structural walls outweighs the microscopic models. The skill level, computational time and limited access to RC specialized finite element packages prevents the general application of this method in performance based design or assessment of multi-storey shear wall buildings in design offices. Hence, this paper organized to verify capability of nonlinear shell element in commercially available package (Sap2000) in simulating results of some specimens under monotonic and cyclic loads with very oversimplified available cyclic material laws in the analytical tool. The selection of constitutive models, the determination of related parameters of the constituent material and appropriate nonlinear shear model are presented in detail. Adoption of proposed simple model demonstrated that the predicted results follow the overall trend of experimental force-displacement curve. Although, prediction of ultimate strength and the overall shape of hysteresis model agreed to some extent with experiment, the ultimate displacement(significant strength degradation point) prediction remains challenging in some cases.

Keywords: analytical model, nonlinear shell element, structural wall, shear behavior

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4679 Ads on Social Issues: A Tool for Improving Critical Thinking Skills in a Foreign Language Classroom

Authors: Fonseca Jully, Chia Maribel, Rodríguez Ilba

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This paper is a qualitative research report. A group of students form a public university in a small town in Colombia participated in this study which aimed at describing to what extend the use of social ads, published on the internet, helped to develop their critical thinking skills. Students’ productions, field notes, video recordings and direct observation were the instruments and techniques used by the researches in order to gather the data which was analyzed under the principles of grounded theory and triangulation. The implementation of social ads into the classroom evidenced a noticeable improvement in students’ ability to interpret and argue social issues, as well as, their self-improvement in oral and written production in English, as a foreign language.

Keywords: Ads, critical argumentation, critical thinking, social issues

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4678 Trade in Value Added: The Case of the Central and Eastern European Countries

Authors: Łukasz Ambroziak

Abstract:

Although the impact of the production fragmentation on trade flows has been examined many times since the 1990s, the research was not comprehensive because of the limitations in traditional trade statistics. Early 2010s the complex databases containing world input-output tables (or indicators calculated on their basis) has made available. It increased the possibilities of examining the production sharing in the world. The trade statistic in value-added terms enables us better to estimate trade changes resulted from the internationalisation and globalisation as well as benefits of the countries from international trade. In the literature, there are many research studies on this topic. Unfortunately, trade in value added of the Central and Eastern European Countries (CEECs) has been so far insufficiently studied. Thus, the aim of the paper is to present changes in value added trade of the CEECs (Bulgaria, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia and Slovenia) in the period of 1995-2011. The concept 'trade in value added' or 'value added trade' is defined as the value added of a country which is directly and indirectly embodied in final consumption of another country. The typical question would be: 'How much value added is created in a country due to final consumption in the other countries?' The data will be downloaded from the World Input-Output Database (WIOD). The structure of this paper is as follows. First, theoretical and methodological aspects related to the application of the input-output tables in the trade analysis will be studied. Second, a brief survey of the empirical literature on this topic will be presented. Third, changes in exports and imports in value added of the CEECs will be analysed. A special attention will be paid to the differences in bilateral trade balances using traditional trade statistics (in gross terms) on one side, and value added statistics on the other. Next, in order to identify factors influencing value added exports and value added imports of the CEECs the generalised gravity model, based on panel data, will be used. The dependent variables will be value added exports and imports. The independent variables will be, among others, the level of GDP of trading partners, the level of GDP per capita of trading partners, the differences in GDP per capita, the level of the FDI inward stock, the geographical distance, the existence (or non-existence) of common border, the membership (or not) in preferential trade agreements or in the EU. For comparison, an estimation will also be made based on exports and imports in gross terms. The initial research results show that the gravity model better explained determinants of trade in value added than gross trade (R2 in the former is higher). The independent variables had the same direction of impact both on value added exports/imports and gross exports/imports. Only value of coefficients differs. The most difference concerned geographical distance. It had smaller impact on trade in value added than gross trade.

Keywords: central and eastern European countries, gravity model, input-output tables, trade in value added

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4677 Innovations in the Lithium Chain Value

Authors: Fiúza A., Góis J. Leite M., Braga H., Lima A., Jorge P., Moutela P., Martins L., Futuro A.

Abstract:

Lepidolite is an important lithium mineral that, to the author’s best knowledge, has not been used to produce lithium hydroxide, necessary for energy conversion to electric vehicles. Alkaline leaching of lithium concentrates allows the establishment of a production diagram avoiding most of the environmental drawbacks that are associated with the usage of acid reagents. The tested processes involve a pretreatment by digestion at high temperatures with additives, followed by leaching at hot atmospheric pressure. The solutions obtained must be compatible with solutions from the leaching of spodumene concentrates, allowing the development of a common treatment diagram, an important accomplishment for the feasible exploitation of Portuguese resources. Statistical programming and interpretation techniques are used to minimize the laboratory effort required by conventional approaches and also allow phenomenological comprehension.

Keywords: artificial intelligence, tailings free process, ferroelectric electrolyte battery, life cycle assessment

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4676 Design and Implementation of Smart Watch Textile Antenna for Wi-Fi Bio-Medical Applications in Millimetric Wave Band

Authors: M. G. Ghanem, A. M. M. A. Allam, Diaa E. Fawzy, Mehmet Faruk Cengiz

Abstract:

This paper is devoted to the design and implementation of a smartwatch textile antenna for Wi-Fi bio-medical applications in millimetric wave bands. The antenna is implemented on a leather textile-based substrate to be embedded in a smartwatch. It enables the watch to pick Wi-Fi signals without the need to be connected to a mobile through Bluetooth. It operates at 60 GHz or WiGig (Wireless Gigabit Alliance) band with a wide band for higher rate applications. It also could be implemented over many stratified layers of the body organisms to be used in the diagnosis of many diseases like diabetes and cancer. The structure is designed and simulated using CST (Studio Suite) program. The wearable patch antenna has an octagon shape, and it is implemented on leather material that acts as a flexible substrate with a size of 5.632 x 6.4 x 2 mm3, a relative permittivity of 2.95, and a loss tangent of 0.006. The feeding is carried out using differential feed (discrete port in CST). The work provides five antenna implementations; antenna without ground, a ground is added at the back of the antenna in order to increase the antenna gain, the substrate dimensions are increased to 15 x 30 mm2 to resemble the real hand watch size, layers of skin and fat are added under the ground of the antenna to study the effect of human body tissues human on the antenna performance. Finally, the whole structure is bent. It is found that the antenna can achieve a simulated peak realized gain in dB of 5.68, 7.28, 6.15, 3.03, and 4.37 for antenna without ground, antenna with the ground, antenna with larger substrate dimensions, antenna with skin and fat, and bent structure, respectively. The antenna with ground exhibits high gain; while adding the human organisms absorption, the gain is degraded because of human absorption. The bent structure contributes to higher gain.

Keywords: bio medical engineering, millimetric wave, smart watch, textile antennas, Wi-Fi

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4675 Data Envelopment Analysis of Allocative Efficiency among Small-Scale Tuber Crop Farmers in North-Central, Nigeria

Authors: Akindele Ojo, Olanike Ojo, Agatha Oseghale

Abstract:

The empirical study examined the allocative efficiency of small holder tuber crop farmers in North central, Nigeria. Data used for the study were obtained from primary source using a multi-stage sampling technique with structured questionnaires administered to 300 randomly selected tuber crop farmers from the study area. Descriptive statistics, data envelopment analysis and Tobit regression model were used to analyze the data. The DEA result on the classification of the farmers into efficient and inefficient farmers showed that 17.67% of the sampled tuber crop farmers in the study area were operating at frontier and optimum level of production with mean allocative efficiency of 1.00. This shows that 82.33% of the farmers in the study area can still improve on their level of efficiency through better utilization of available resources, given the current state of technology. The results of the Tobit model for factors influencing allocative inefficiency in the study area showed that as the year of farming experience, level of education, cooperative society membership, extension contacts, credit access and farm size increased in the study area, the allocative inefficiency of the farmers decreased. The results on effects of the significant determinants of allocative inefficiency at various distribution levels revealed that allocative efficiency increased from 22% to 34% as the farmer acquired more farming experience. The allocative efficiency index of farmers that belonged to cooperative society was 0.23 while their counterparts without cooperative society had index value of 0.21. The result also showed that allocative efficiency increased from 0.43 as farmer acquired high formal education and decreased to 0.16 with farmers with non-formal education. The efficiency level in the allocation of resources increased with more contact with extension services as the allocative efficeincy index increased from 0.16 to 0.31 with frequency of extension contact increasing from zero contact to maximum of twenty contacts per annum. These results confirm that increase in year of farming experience, level of education, cooperative society membership, extension contacts, credit access and farm size leads to increases efficiency. The results further show that the age of the farmers had 32% input to the efficiency but reduces to an average of 15%, as the farmer grows old. It is therefore recommended that enhanced research, extension delivery and farm advisory services should be put in place for farmers who did not attain optimum frontier level to learn how to attain the remaining 74.39% level of allocative efficiency through a better production practices from the robustly efficient farms. This will go a long way to increase the efficiency level of the farmers in the study area.

Keywords: allocative efficiency, DEA, Tobit regression, tuber crop

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4674 Chitosan-Aluminum Monostearate Dispersion as Fabricating Liquid for Constructing Controlled Drug Release Matrix

Authors: Kotchamon Yodkhum, Thawatchai Phaechamud

Abstract:

Hydrophobic chitosan-based materials have been developed as controlled drug delivery system. This study was aimed to prepare and evaluate chitosan-aluminum monostearate composite dispersion (CLA) as fabricating liquid for construct a hydrophobic, controlled-release solid drug delivery matrix. This work was attempted to blend hydrophobic substance, aluminum monostearate (AMS), with chitosan in acidic aqueous medium without using any surfactants or grafting reaction, and high temperature during mixing that are normally performed when preparing hydrophobic chitosan system. Lactic acid solution (2%w/v) was employed as chitosan solvent. CLA dispersion was prepared by dispersing different amounts of AMS (1-20% w/w) in chitosan solution (4% w/w) with continuous agitation using magnetic stirrer for 24 h. Effect of AMS amount on physicochemical properties of the dispersion such as viscosity, rheology and particle size was evaluated. Morphology of chitosan-AMS complex (dispersant) was observed under inverted microscope and atomic force microscope. Stability of CLA dispersions was evaluated after preparation within 48 h. CLA dispersions containing AMS less than 5 % w/w exhibited rheological behavior as Newtonian while that containing higher AMS amount exhibited as pseudoplastic. Particle size of the dispersant was significantly smaller when AMS amount was increased up to 5% w/w and was not different between the higher AMS amount system. Morphology of the dispersant under inverted microscope displayed irregular shape and their size exhibited the same trend with particle size measurement. Observation of the dispersion stability revealed that phase separation occurred faster in the system containing higher AMS amount which indicated lower stability of the system. However, the dispersions were homogeneous and stable more than 12 hours after preparation that enough for fabrication process. The prepared dispersions had ability to be fabricated as a porous matrix via lyophilization technique.

Keywords: chitosan, aluminum monostearate, dispersion, controlled-release

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4673 Muscle and Cerebral Regional Oxygenation in Preterm Infants with Shock Using Near-Infrared Spectroscopy

Authors: Virany Diana, Martono Tri Utomo, Risa Etika

Abstract:

Background: Shock is one severe condition that can be a major cause of morbidity and mortality in the Neonatal Intensive Care Unit. Preterm infants are very susceptible to shock caused by many complications such as asphyxia, patent ductus arteriosus, intra ventricle haemorrhage, necrotizing enterocolitis, persistent pulmonal hypertension of the newborn, and septicaemia. Limited hemodynamic monitoring for early detection of shock causes delayed intervention and comprises the outcomes. Clinical parameters still used in neonatal shock detection, such as Capillary Refill Time, heart rate, cold extremity, and urine production. Blood pressure is most frequently used to evaluate preterm's circulation, but hypotension indicates uncompensated shock. Near-infrared spectroscopy (NIRS) is known as a noninvasive tool for monitoring and detecting the state of inadequate tissue perfusion. Muscle oxygen saturation shows decreased cardiac output earlier than systemic parameters of tissue oxygenation when cerebral regional oxygen saturation is still stabilized by autoregulation. However, to our best knowledge, until now, no study has analyzed the decrease of muscle oxygen regional saturation (mRSO₂) and the ratio of muscle and cerebral oxygen regional saturation (mRSO₂/cRSO₂) by NIRS in preterm with shock. Purpose: The purpose of this study is to analyze the decrease of mRSO₂ and ratio of muscle to cerebral oxygen regional saturation (mRSO₂/cRSO₂) by NIRS in preterm with shock. Patients and Methods: This cross-sectional study was conducted on preterm infants with 28-34 weeks gestational age, admitted to the NICU of Dr. Soetomo Hospital from November to January 2022. Patients were classified into two groups: shock and non-shock. The diagnosis of shock is based on clinical criteria (tachycardia, prolonged CRT, cold extremity, decreased urine production, and MAP Blood Pressure less than GA in weeks). Measurement of mRSO₂ and cRSO₂ by NIRS was performed by the doctor in charge when the patient came to NICU. Results: We enrolled 40 preterm infants. The initial conventional hemodynamic parameter as the basic diagnosis of shock showed significant differences in all variables. Preterm with shock had higher mean HR (186.45±1.5), lower MAP (29.8±2.1), and lower SBP (45.1±4.28) than non-shock children, and most had a prolonged CRT. The patients’ outcome was not a significant difference between shock and non-shock patients. The mean mRSO₂ in the shock and non-shock groups were 33,65 ± 11,32 vs. 69,15 ± 3,96 (p=0.001), and the mean ratio mRSO₂/cRSO₂ 0,45 ± 0,12 vs. 0,84 ± 0,43 (p=0,001), were significantly different. The mean cRSO₂ in the shock and non-shock groups were 71,60 ± 4,90 vs. 81,85 ± 7,85 (p 0.082), not significantly different. Conclusion: The decrease of mRSO₂ and ratio of mRSO₂/cRSO₂ can differentiate between shock and non-shock in the preterm infant when cRSO₂ is still normal.

Keywords: preterm infant, regional muscle oxygen saturation, regional cerebral oxygen saturation, NIRS, shock

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4672 Thermal Method Production of the Hydroxyapatite from Bone By-Products from Meat Industry

Authors: Agnieszka Sobczak-Kupiec, Dagmara Malina, Klaudia Pluta, Wioletta Florkiewicz, Bozena Tyliszczak

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Introduction: Request for compound of phosphorus grows continuously, thus, it is searched for alternative sources of this element. One of these sources could be by-products from meat industry which contain prominent quantity of phosphorus compounds. Hydroxyapatite, which is natural component of animal and human bones, is leading material applied in bone surgery and also in stomatology. This is material, which is biocompatible, bioactive and osteoinductive. Methodology: Hydroxyapatite preparation: As a raw material was applied deproteinized and defatted bone pulp called bone sludge, which was formed as waste in deproteinization process of bones, in which a protein hydrolysate was the main product. Hydroxyapatite was received in calcining process in chamber kiln with electric heating in air atmosphere in two stages. In the first stage, material was calcining in temperature 600°C within 3 hours. In the next stage unified material was calcining in three different temperatures (750°C, 850°C and 950°C) keeping material in maximum temperature within 3.0 hours. Bone sludge: Bone sludge was formed as waste in deproteinization process of bones, in which a protein hydrolysate was the main product. Pork bones coming from the partition of meat were used as a raw material for the production of the protein hydrolysate. After disintegration, a mixture of bone pulp and water with a small amount of lactic acid was boiled at temperature 130-135°C and under pressure4 bar. After 3-3.5 hours boiled-out bones were separated on a sieve, and the solution of protein-fat hydrolysate got into a decanter, where bone sludge was separated from it. Results of the study: The phase composition was analyzed by roentgenographic method. Hydroxyapatite was the only crystalline phase observed in all the calcining products. XRD investigation was shown that crystallization degree of hydroxyapatite was increased with calcining temperature. Conclusion: The researches were shown that phosphorus content is around 12%, whereas, calcium content amounts to 28% on average. The conducted researches on bone-waste calcining at the temperatures of 750-950°C confirmed that thermal utilization of deproteinized bone-waste was possible. X-ray investigations were confirmed that hydroxyapatite is the main component of calcining products, and also XRD investigation was shown that crystallization degree of hydroxyapatite was increased with calcining temperature. Contents of calcium and phosphorus were distinctly increased with calcining temperature, whereas contents of phosphorus soluble in acids were decreased. It could be connected with higher crystallization degree of material received in higher temperatures and its stable structure. Acknowledgements: “The authors would like to thank the The National Centre for Research and Development (Grant no: LIDER//037/481/L-5/13/NCBR/2014) for providing financial support to this project”.

Keywords: bone by-products, bone sludge, calcination, hydroxyapatite

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4671 Social Business: Opportunities and Challenges

Authors: Muhammad Mustafizur Rahaman

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Social business is a new concept in the field of Business Economics and Capitalist Economy. It has increased the importance in economic and social development in emerging economies. Professor Muhammad Yunus is the founding father of the notion. While conventional business underscores profit maximization as a core business principle, social business calls for addressing social problems at the expense of profit. This underlying principle gives social business advantageous position over conventional businesses to serve those who live at the bottom of the pyramid. It also poses grave challenges to the social business because social business sacrifices profit at one hand and seeks financial sustainability on the other. For the sake of its financial sustainability, the social business might increase the price of its product or service which might lower its social impact, thus, makes the business self-defeating. Therefore, social business should be more innovative in every business process including production, marketing, and management. Otherwise, the business is unlikely to be driven out from the society.

Keywords: innovativeness, self-defeat, social business, social problem

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4670 Green Logistics Management and Performance for Thailand’s Logistic Enterprises

Authors: Kittipong Tissayakorn, Fumio Akagi, Yu Song

Abstract:

Logistics is the integrated management of all of the activities required to move products through the supply chain. For a typical product, this supply chain extends from a raw material source through the production and distribution system to the point of consumption and the associated reverse logistics. The logistical activities are comprised of freight transport, storage, inventory management, materials handling and all related information processing. This paper analyzes the green management system of logistics enterprise for Thailand and advances the concept of Green Logistics, which should be held by the public. In addition, it proposes that the government should strengthen its supervision and support for green logistics, and companies should construct self-disciplined green logistics management systems and corresponding processes, a reverse logistics management system and a modern green logistics information collection and management system.

Keywords: logistics, green logistics, management system, ecological economics

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4669 STML: Service Type-Checking Markup Language for Services of Web Components

Authors: Saqib Rasool, Adnan N. Mian

Abstract:

Web components are introduced as the latest standard of HTML5 for writing modular web interfaces for ensuring maintainability through the isolated scope of web components. Reusability can also be achieved by sharing plug-and-play web components that can be used as off-the-shelf components by other developers. A web component encapsulates all the required HTML, CSS and JavaScript code as a standalone package which must be imported for integrating a web component within an existing web interface. It is then followed by the integration of web component with the web services for dynamically populating its content. Since web components are reusable as off-the-shelf components, these must be equipped with some mechanism for ensuring their proper integration with web services. The consistency of a service behavior can be verified through type-checking. This is one of the popular solutions for improving the quality of code in many programming languages. However, HTML does not provide type checking as it is a markup language and not a programming language. The contribution of this work is to introduce a new extension of HTML called Service Type-checking Markup Language (STML) for adding support of type checking in HTML for JSON based REST services. STML can be used for defining the expected data types of response from JSON based REST services which will be used for populating the content within HTML elements of a web component. Although JSON has five data types viz. string, number, boolean, object and array but STML is made to supports only string, number and object. This is because of the fact that both object and array are considered as string, when populated in HTML elements. In order to define the data type of any HTML element, developer just needs to add the custom STML attributes of st-string, st-number and st-boolean for string, number and boolean respectively. These all annotations of STML are used by the developer who is writing a web component and it enables the other developers to use automated type-checking for ensuring the proper integration of their REST services with the same web component. Two utilities have been written for developers who are using STML based web components. One of these utilities is used for automated type-checking during the development phase. It uses the browser console for showing the error description if integrated web service is not returning the response with expected data type. The other utility is a Gulp based command line utility for removing the STML attributes before going in production. This ensures the delivery of STML free web pages in the production environment. Both of these utilities have been tested to perform type checking of REST services through STML based web components and results have confirmed the feasibility of evaluating service behavior only through HTML. Currently, STML is designed for automated type-checking of integrated REST services but it can be extended to introduce a complete service testing suite based on HTML only, and it will transform STML from Service Type-checking Markup Language to Service Testing Markup Language.

Keywords: REST, STML, type checking, web component

Procedia PDF Downloads 239
4668 Production and Mechanical Characterization of Ballistic Thermoplastic Composite Materials

Authors: D. Korsacilar, C. Atas

Abstract:

In this study, first thermoplastic composite materials/plates that have high ballistic impact resistance were produced. For this purpose, the thermoplastic prepreg and the vacuum bagging technique were used to produce a composite material. Thermoplastic prepregs (resin-impregnated fiber) that are supplied ready to be used, namely high-density polyethylene (HDPE) was chosen as matrix and unidirectional glass fiber was used as reinforcement. In order to compare the fiber configuration effect on mechanical properties, unidirectional and biaxial prepregs were used. Then the microstructural properties of the composites were investigated with scanning electron microscopy (SEM) analysis. Impact properties of the composites were examined by Charpy impact test and tensile mechanical tests and then the effects of ultraviolet irradiation were investigated on mechanical performance.

Keywords: ballistic, composite, thermoplastic, prepreg

Procedia PDF Downloads 428
4667 FlameCens: Visualization of Expressive Deviations in Music Performance

Authors: Y. Trantafyllou, C. Alexandraki

Abstract:

Music interpretation accounts to the way musicians shape their performance by deliberately deviating from composers’ intentions, which are commonly communicated via some form of music transcription, such as a music score. For transcribed and non-improvised music, music expression is manifested by introducing subtle deviations in tempo, dynamics and articulation during the evolution of performance. This paper presents an application, named FlameCens, which, given two recordings of the same piece of music, presumably performed by different musicians, allow visualising deviations in tempo and dynamics during playback. The application may also compare a certain performance to the music score of that piece (i.e. MIDI file), which may be thought of as an expression-neutral representation of that piece, hence depicting the expressive queues employed by certain performers. FlameCens uses the Dynamic Time Warping algorithm to compare two audio sequences, based on CENS (Chroma Energy distribution Normalized Statistics) audio features. Expressive deviations are illustrated in a moving flame, which is generated by an animation of particles. The length of the flame is mapped to deviations in dynamics, while the slope of the flame is mapped to tempo deviations so that faster tempo changes the slope to the right and slower tempo changes the slope to the left. Constant slope signifies no tempo deviation. The detected deviations in tempo and dynamics can be additionally recorded in a text file, which allows for offline investigation. Moreover, in the case of monophonic music, the color of particles is used to convey the pitch of the notes during performance. FlameCens has been implemented in Python and it is openly available via GitHub. The application has been experimentally validated for different music genres including classical, contemporary, jazz and popular music. These experiments revealed that FlameCens can be a valuable tool for music specialists (i.e. musicians or musicologists) to investigate the expressive performance strategies employed by different musicians, as well as for music audience to enhance their listening experience.

Keywords: audio synchronization, computational music analysis, expressive music performance, information visualization

Procedia PDF Downloads 118
4666 Investigations on the Influence of Web Openings on the Load Bearing Behavior of Steel Beams

Authors: Felix Eyben, Simon Schaffrath, Markus Feldmann

Abstract:

A building should maximize the potential for use through its design. Therefore, flexible use is always important when designing a steel structure. To create flexibility, steel beams with web openings are increasingly used, because these offer the advantage that cables, pipes and other technical equipment can easily be routed through without detours, allowing for more space-saving and aesthetically pleasing construction. This can also significantly reduce the height of ceiling systems. Until now, beams with web openings were not explicitly considered in the European standard. However, this is to be done with the new EN 1993-1-13, in which design rules for different opening forms are defined. In order to further develop the design concepts, beams with web openings under bending are therefore to be investigated in terms of damage mechanics as part of a German national research project aiming to optimize the verifications for steel structures based on a wider database and a validated damage prediction. For this purpose, first, fundamental factors influencing the load-bearing behavior of girders with web openings under bending load were investigated numerically without taking material damage into account. Various parameter studies were carried out for this purpose. For example, the factors under study were the opening shape, size and position as well as structural aspects as the span length, arrangement of stiffeners and loading situation. The load-bearing behavior is evaluated using resulting load-deformation curves. These results are compared with the design rules and critically analyzed. Experimental tests are also planned based on these results. Moreover, the implementation of damage mechanics in the form of the modified Bai-Wierzbicki model was examined. After the experimental tests will have been carried out, the numerical models are validated and further influencing factors will be investigated on the basis of parametric studies.

Keywords: damage mechanics, finite element, steel structures, web openings

Procedia PDF Downloads 157
4665 Stability Design by Geometrical Nonlinear Analysis Using Equivalent Geometric Imperfections

Authors: S. Fominow, C. Dobert

Abstract:

The present article describes the research that deals with the development of equivalent geometric imperfections for the stability design of steel members considering lateral-torsional buckling. The application of these equivalent imperfections takes into account the stiffness-reducing effects due to inelasticity and residual stresses, which lead to a reduction of the load carrying capacity of slender members and structures. This allows the application of a simplified design method, that is performed in three steps. Application of equivalent geometric imperfections, determination of internal forces using geometrical non-linear analysis (GNIA) and verification of the cross-section resistance at the most unfavourable location. All three verification steps are closely related and influence the results. The derivation of the equivalent imperfections was carried out in several steps. First, reference lateral-torsional buckling resistances for various rolled I-sections, slenderness grades, load shapes and steel grades were determined. This was done either with geometric and material non-linear analysis with geometrical imperfections and residual stresses (GMNIA) or for standard cases based on the equivalent member method. With the aim of obtaining identical lateral-torsional buckling resistances as the reference resistances from the application of the design method, the required sizes for equivalent imperfections were derived. For this purpose, a program based on the FEM method has been developed. Based on these results, several proposals for the specification of equivalent geometric imperfections have been developed. These differ in the shape of the applied equivalent geometric imperfection, the model of the cross-sectional resistance and the steel grade. The proposed design methods allow a wide range of applications and a reliable calculation of the lateral-torsional buckling resistances, as comparisons between the calculated resistances and the reference resistances have shown.

Keywords: equivalent geometric imperfections, GMNIA, lateral-torsional buckling, non-linear finite element analysis

Procedia PDF Downloads 146
4664 Investigating the Process Kinetics and Nitrogen Gas Production in Anammox Hybrid Reactor with Special Emphasis on the Role of Filter Media

Authors: Swati Tomar, Sunil Kumar Gupta

Abstract:

Anammox is a novel and promising technology that has changed the traditional concept of biological nitrogen removal. The process facilitates direct oxidation of ammonical nitrogen under anaerobic conditions with nitrite as an electron acceptor without the addition of external carbon sources. The present study investigated the feasibility of anammox hybrid reactor (AHR) combining the dual advantages of suspended and attached growth media for biodegradation of ammonical nitrogen in wastewater. The experimental unit consisted of 4 nos. of 5L capacity AHR inoculated with mixed seed culture containing anoxic and activated sludge (1:1). The process was established by feeding the reactors with synthetic wastewater containing NH4-H and NO2-N in the ratio 1:1 at HRT (hydraulic retention time) of 1 day. The reactors were gradually acclimated to higher ammonium concentration till it attained pseudo steady state removal at a total nitrogen concentration of 1200 mg/l. During this period, the performance of the AHR was monitored at twelve different HRTs varying from 0.25-3.0 d with increasing NLR from 0.4 to 4.8 kg N/m3d. AHR demonstrated significantly higher nitrogen removal (95.1%) at optimal HRT of 1 day. Filter media in AHR contributed an additional 27.2% ammonium removal in addition to 72% reduction in the sludge washout rate. This may be attributed to the functional mechanism of filter media which acts as a mechanical sieve and reduces the sludge washout rate many folds. This enhances the biomass retention capacity of the reactor by 25%, which is the key parameter for successful operation of high rate bioreactors. The effluent nitrate concentration, which is one of the bottlenecks of anammox process was also minimised significantly (42.3-52.3 mg/L). Process kinetics was evaluated using first order and Grau-second order models. The first-order substrate removal rate constant was found as 13.0 d-1. Model validation revealed that Grau second order model was more precise and predicted effluent nitrogen concentration with least error (1.84±10%). A new mathematical model based on mass balance was developed to predict N2 gas in AHR. The mass balance model derived from total nitrogen dictated significantly higher correlation (R2=0.986) and predicted N2 gas with least error of precision (0.12±8.49%). SEM study of biomass indicated the presence of the heterogeneous population of cocci and rod shaped bacteria of average diameter varying from 1.2-1.5 mm. Owing to enhanced NRE coupled with meagre production of effluent nitrate and its ability to retain high biomass, AHR proved to be the most competitive reactor configuration for dealing with nitrogen laden wastewater.

Keywords: anammox, filter media, kinetics, nitrogen removal

Procedia PDF Downloads 373
4663 Total Productive Maintenance (TPM) as a Strategy for Competitiveness

Authors: Ignatio Madanhire, Charles Mbohwa

Abstract:

This research examines the effect of a human resource strategy and the overall equipment effectiveness as well as assessing how the combination of the two can increase a firm’s productivity. The human resource aspect is looked at in detail to assess motivation of operators through training to reduce wastage on the manufacturing shop floor. The waste was attributed to operators, maintenance personal, idle machines, idle manpower and break downs. This work seeks to investigate the concept of Total Productive Maintenance (TPM) in addressing these short comings in the manufacturing case study. The impact of TPM to increase production while, as well as increasing employee morale and job satisfaction is assessed. This can be resource material for practitioners who seek to improve overall equipment efficiency (OEE) to achieve higher level productivity and competitiveness.

Keywords: maintenance, TPM, efficiency, productivity, strategy

Procedia PDF Downloads 408
4662 A Multi-Beneficial Gift of Nature (Noni Fruit): Nutritional, Functional, and Post-Harvest Aspects

Authors: Mahsa Moteshakeri

Abstract:

Morinda citrifolia L., a miracle fruit with common name of Noni, has been widely used as food and traditional medicine in the Polynesians culture. Current scientific evidences have proved the therapeautical and nutritional properties of this fruit so that its extensive production in tropical regions in recent years has emerged a competitive global Noni market mainly as a dietary supplement in the form of juice or tablet. However, there is not much record on the processing method applied on fresh fruit postharvest or even its mechanism of action in controlling diseases. This review aimed to provide a comprehensive data on phytochemicals, technical, and nutritional advances on Noni fruit and recent patents published, as well as medicinal properties of the fruit in order to benefit future investigations on this precious fruit either in industrial or therapeautical section.

Keywords: noni fruit, phytochemicals, therapeautic properties of fruit, nutritional properties of fruit

Procedia PDF Downloads 353
4661 Assesment of Financial Performance: An Empirical Study of Crude Oil and Natural Gas Companies in India

Authors: Palash Bandyopadhyay

Abstract:

Background and significance of the study: Crude oil and natural gas is of crucial importance due to its increasing demand in India. The demand has been increased because of change of lifestyle overtime. Since India has poor utilization of oil production capacity, constantly the import of it has been increased progressively day by day. This ultimately hit the foreign exchange reserves of India, however it negatively affect the Indian economy as well. The financial performance of crude oil and natural gas companies in India has been trimmed down year after year because of underutilization of production capacity, enhancement of demand, change in life style, and change in import bill and outflows of foreign currencies. In this background, the current study seeks to measure the financial performance of crude oil and natural gas companies of India in the post liberalization period. Keeping in view of this, this study assesses the financial performance in terms of liquidity management, solvency, efficiency, financial stability, and profitability of the companies under study. Methodology: This research work is encircled on yearly ratio data collected from Centre for Monitoring Indian Economy (CMIE) Prowess database for the periods between 1993-94 and 2012-13 with 20 observations using liquidity, solvency and efficiency indicators, profitability indicators and financial stability indicators of all the major crude oil and natural gas companies in India. In the course of analysis, descriptive statistics, correlation statistics, and linear regression test have been utilized. Major findings: Descriptive statistics indicate that liquidity position is satisfactory in case of three crude oil and natural gas companies (Oil and Natural Gas Companies Videsh Limited, Oil India Limited and Selan exploration and transportation Limited) out of selected companies under study but solvency position is satisfactory only for one company (Oil and Natural Gas Companies Videsh Limited). However, efficiency analysis points out that Oil and Natural Gas Companies Videsh Limited performs effectively the management of inventory, receivables, and payables, but the overall liquidity management is not well. Profitability position is very much satisfactory in case of all the companies except Tata Petrodyne Limited, but profitability management is not satisfactory for all the companies under study. Financial stability analysis shows that all the companies are more dependent on debt capital, which bears a financial risk. Correlation and regression test results illustrates that profitability is positively and negatively associated with liquidity, solvency, efficiency, and financial stability indicators. Concluding statement: Management of liquidity and profitability of crude oil and natural gas companies in India should have been improved through controlling unnecessary imports in spite of the heavy demand of crude oil and natural gas in India and proper utilization of domestic oil reserves. At the same time, Indian government has to concern about rupee depreciation and interest rates.

Keywords: financial performance, crude oil and natural gas companies, India, linear regression

Procedia PDF Downloads 310
4660 Value Adding of Waste Biomass of Capsicum and Chilli Crops for Medical and Health Supplement Industries

Authors: Mursleen Yasin, Sunil Panchal, Michelle Mak, Zhonghua Chen

Abstract:

“The use of agricultural and horticultural waste to obtain beneficial products. Thus reduce its environmental impact and help the general population.” Every year 20 billion dollars of food is wasted in the world. All the energy, resources, nutrients and metabolites are lost to the landfills as well. On farm production losses are a main issue in agriculture. Almost 25% vegetables never leave the farm because they are not considered perfect for supermarkets and treated as waste material along with the rest of the plant parts. For capsicums, this waste is 56% of the total crop. Capsicum genus is enriched with a group of compounds called capsaicinoids which are a source of spiciness of these fruits. Capsaicin and dihydrocapsaicin are the major members comprising almost 90% of this group. The major production and accumulation site is the non-edible part of fruit i.e., placenta. Other parts of the plant, like stem, leaves, pericarp and seeds, also contain these pungent compounds. Capsaicinoids are enriched with properties like analgesic, antioxidants, anti-inflammatory, antibacterial, anti-virulence anti-carcinogenic, chemo preventive, chemotherapeutic, antidiabetic etc. They are also effective in treating problems related to gastrointestinal tract, lowering cholesterol and triglycerides in obesity. The aim of the study is to develop a standardised technique for capsaicinoids extraction and to identify better nutrient treatment for fruit and capsaicinoids yield. For research 3 capsicum and 2 chilli varieties were grown in a high-tech glass house facility in Sydney, Australia. Plants were treated with three levels of nutrient treatments i.e., EC 1.8, EC 2.8 and EC 3.8 in order to check its effect on fruit yield and capsaicinoids concentration. Solvent extraction procedure is used with 75% ethanol to extract these secondary metabolites. Physiological, post-harvest and waste biomass measurement and metabolomic analysis are also performed. The results showed that EC 2.8 gave the better fruit yield of capsicums, and those fruits have the higher capsaicinoids concentration. For chillies, higher EC levels had better results than lower treatment. The UHPLC analysis is done to quantify the compounds, and a decrease in capsaicin concentration is observed with the crop maturation. The outcome of this project is a sustainable technique for extraction of capsaicinoids which can easily be adopted by farmers. In this way, farmers can help in value adding of waste by extracting and selling capsaicinoids to nutraceutical and pharmaceutical industries and also earn some secondary income from the 56% waste of capsicum crop.

Keywords: capsaicinoids, plant waste, capsicum, solvent extraction, waste biomass

Procedia PDF Downloads 66
4659 Production of High-Content Fructo-Oligosaccharides

Authors: C. Nobre, C. C. Castro, A.-L. Hantson, J. A. Teixeira, L. R. Rodrigues, G. De Weireld

Abstract:

Fructo-oligosaccharides (FOS) are produced from sucrose by Aureobasidium pullulans in yields between 40-60% (w/w). To increase the amount of FOS it is necessary to remove the small, non-prebiotic sugars, present. Two methods for producing high-purity FOS have been developed: the use of microorganisms able to consume small saccharides; and the use of continuous chromatography to separate sugars: simulated moving bed (SMB). It is herein proposed the combination of both methods. The aim of this study is to optimize the composition of the fermentative broth (in terms of salts and sugars) that will be further purified by SMB. A yield of 0.63 gFOS.g Sucrose-1 was obtained with A. pullulans using low amounts of salts in the initial fermentative broth. By removing the small sugars, Saccharomyces cerevisiae and Zymomonas mobilis increased the percentage of FOS from around 56.0% to 83% (w/w) in average, losing only 10% (w/w) of FOS during the recovery process.

Keywords: fructo-oligosaccharides, microbial treatment, Saccharomyces cerevisiae, Zymomonas mobilis

Procedia PDF Downloads 294
4658 Application of Multiwall Carbon Nanotubes with Anionic Surfactant to Cement Paste

Authors: Maciej Szelag

Abstract:

The discovery of the carbon nanotubes (CNT), has led to a breakthrough in the material engineering. The CNT is characterized by very large surface area, very high Young's modulus (about 2 TPa), unmatched durability, high tensile strength (about 50 GPa) and bending strength. Their diameter usually oscillates in the range from 1 to 100 nm, and the length from 10 nm to 10-2 m. The relatively new approach is the CNT’s application in the concrete technology. The biggest problem in the use of the CNT to cement composites is their uneven dispersion and low adhesion to the cement paste. Putting the nanotubes alone into the cement matrix does not produce any effect because they tend to agglomerate, due to their large surface area. Most often, the CNT is used as an aqueous suspension in the presence of a surfactant that has previously been sonicated. The paper presents the results of investigations of the basic physical properties (apparent density, shrinkage) and mechanical properties (compression and tensile strength) of cement paste with the addition of the multiwall carbon nanotubes (MWCNT). The studies were carried out on four series of specimens (made of two different Portland Cement). Within each series, samples were made with three w/c ratios – 0.4, 0.5, 0.6 (water/cement). Two series were an unmodified cement matrix. In the remaining two series, the MWCNT was added in amount of 0.1% by cement’s weight. The MWCNT was used as an aqueous dispersion in the presence of a surfactant – SDS – sodium dodecyl sulfate (C₁₂H₂₅OSO₂ONa). So prepared aqueous solution was sonicated for 30 minutes. Then the MWCNT aqueous dispersion and cement were mixed using a mechanical stirrer. The parameters were tested after 28 days of maturation. Additionally, the change of these parameters was determined after samples temperature loading at 250°C for 4 hours (thermal shock). Measurement of the apparent density indicated that cement paste with the MWCNT addition was about 30% lighter than conventional cement matrix. This is due to the fact that the use of the MWCNT water dispersion in the presence of surfactant in the form of SDS resulted in the formation of air pores, which were trapped in the volume of the material. SDS as an anionic surfactant exhibits characteristics specific to blowing agents – gaseous and foaming substances. Because of the increased porosity of the cement paste with the MWCNT, they have obtained lower compressive and tensile strengths compared to the cement paste without additive. It has been observed, however, that the smallest decreases in the compressive and tensile strength after exposure to the elevated temperature achieved samples with the MWCNT. The MWCNT (well dispersed in the cement matrix) can form bridges between hydrates in a nanoscale of the material’s structure. Thus, this may result in an increase in the coherent cohesion of the cement material subjected to a thermal shock. The obtained material could be used for the production of an aerated concrete or using lightweight aggregates for the production of a lightweight concrete.

Keywords: cement paste, elevated temperature, mechanical parameters, multiwall carbon nanotubes, physical parameters, SDS

Procedia PDF Downloads 342