Search results for: chemical etching

Authors: Zakirul Islam, Yugo Kumokawa, Quoc Thinh Tran, Motoki Kubo

Abstract:

Clubroot is a disease of cruciferous plant caused by soil born pathogen Plasmodiophora brassicae and can significantly limit the production through rapid spreading. The present study was designed to investigate the effect of cultivation practices (chemical and organic soils) on clubroot disease development in Brassica rapa. Disease index and root bacterial composition were investigated for both chemical and organic soils. The bacterial biomass and diversity in organic soil were higher than those in chemical soil. Disease severity was distinct for two different cultivation methods. The number of endophytic bacteria decreased in the infected root for both soils. The increased number of endophytic bacterial number led to reduce the proliferation of pathogen spore inside the root and thus reduced the disease severity in organic plants.

Keywords: clubroot disease, bacterial biomass, root infection, disease index, chemical cultivation, organic cultivation

Procedia PDF Downloads 49

Authors: Kanokkan Titipornpun, Tripob Bhongsuwan, Jan Gimsa

Abstract:

The Ko Samui district of Surat Thani province is located in the high amounts of equivalent uranium in the ground surface that is the source of radon. Our research in the Ko Samui district aimed at comparing the indoor radon concentrations between dwellings and workplaces. Measurements of indoor radon concentrations were carried out in 46 dwellings and 127 workplaces, using CR-39 alpha-track detectors in closed-cup. A total of 173 detectors were distributed in 7 sub-districts. The detectors were placed in bedrooms of dwellings and workrooms of workplaces. All detectors were exposed to airborne radon for 90 days. After exposure, the alpha tracks were made visible by chemical etching before they were manually counted under an optical microscope. The track densities were assumed to be correlated with the radon concentration levels. We found that the radon concentrations could be well described by a log-normal distribution. Most concentrations (37%) were found in the range between 16 and 30 Bq.m^-3. The radon concentrations in dwellings and workplaces varied from a minimum of 11 Bq.m^-3 to a maximum of 305 Bq.m^-3. The minimum (11 Bq.m^-3) and maximum (305 Bq.m^-3) values of indoor radon concentrations were found in a workplace and a dwelling, respectively. Only for four samples (3%), the indoor radon concentrations were found to be higher than the reference level recommended by the WHO (100 Bq.m^-3). The overall geometric mean in the surveyed area was 32.6±1.65 Bq.m^-3, which was lower than the worldwide average (39 Bq.m^-3). The statistic comparison of the geometric mean indoor radon concentrations between dwellings and workplaces showed that the geometric mean in dwellings (46.0±1.55 Bq.m^-3) was significantly higher than in workplaces (28.8±1.58 Bq.m^-3) at the 0.05 level. Moreover, our study found that the majority of the bedrooms in dwellings had a closed atmosphere, resulting in poorer ventilation than in most of the workplaces that had access to air flow through open doors and windows at daytime. We consider this to be the main reason for the higher geometric mean indoor radon concentration in dwellings compared to workplaces.

Keywords: CR-39 detector, indoor radon, radon in dwelling, radon in workplace

Procedia PDF Downloads 256

Authors: Bunjirtluk Jintaridth

Abstract:

Utilization of silicon for sustainable rice cultivation in acid sulfate soils was studied for 2 years. The study was conducted on Rungsit soils in Amphoe Tanyaburi, Pathumtani Province. The objectives of this study were to assess the effect of high quality organic fertilizer in combination with silicon and chemical fertilizer on rice yield, chemical soil properties after using soil amendments, and also to assess the economic return. A Randomized Complete Block Design (RCBD) with 10 treatments and 3 replications were employed. The treatments were as follows: 1) control 2) chemical fertilizer (recommended by Land Development Department, LDD 3) silicon 312 kg/ha 4) high quality organic fertilizer at 1875 kg/ha (the recommendation rate by LDD) 5) silicon 156 kg/ha in combination with high quality organic fertilizer 1875 kg/ha 6) silicon at the 312 kg/ha in combination with high quality organic fertilizer 1875 kg/ha 7) silicon 156 kg/ha in combination with chemical fertilizer 8) silicon at the 312 kg/ha in combination with chemical fertilizer 9) silicon 156 kg/ha in combination with ½ chemical fertilizer rate, and 10) silicon 312 kg/ha in combination with ½ chemical fertilizer rate. The results of 2 years indicated the treatment tended to increase soil pH (from 5.1 to 4.7-5.5), percentage of organic matter (from 2.43 to 2.54 - 2.94%); avail. P (from 7.5 to 7-21 mg kg-1 P; ext. K (from 616 to 451-572 mg kg-1 K), ext Ca (from 1962 to 2042.3-4339.7 mg kg-1 Ca); ext Mg (from 1586 to 808.7-900 mg kg-1 Mg); but decrease the ext. Al (from 2.56 to 0.89-2.54 cmol kg-1 Al. Two years average of rice yield, the highest yield was obtained from silicon 156 kg/ha application in combination with high quality organic fertilizer 300 kg/rai (3770 kg/ha), or using silicon at the 312 kg/ha combination with high quality organic fertilizer 300 kg/rai. (3,750 kg/ha). It was noted that chemical fertilizer application with 156 and 312 kg/ha silicon gave only 3,260 และ 3,133 kg/ha, respectively. On the other hand, half rate of chemical fertilizer with 156 and 312 kg/ha with silicon gave the yield of 2,934 และ 3,218 kg/ha, respectively. While high quality organic fertilizer only can produce 3,318 kg/ha as compare to rice yield of 2,812 kg/ha from control. It was noted that the highest economic return was obtained from chemical fertilizer treated plots (886 dollars/ha). Silicon application at the rate of 156 kg/ha in combination with high quality organic fertilizer 1875 kg/ha gave the economic return of 846 dollars/ha, while 312 kg/ha of silicon with chemical fertilizer gave the lowest economic return (697 dollars/ha).

Keywords: rice, high quality organic fertilizer, acid sulfate soil, silicon

Procedia PDF Downloads 130

Authors: Guillaume Morin-Duponchelle, Ahmed Nait Chabane, Benoit Zerr, Pierre Schoesetters

Abstract:

Industrial inspection can be achieved through robotic systems, allowing visual and chemical servoing. A popular scheme for visual servo-controlled robotic is the image-based servoing sys-tems. In this paper, an approach of visual and chemical servoing of a hexapod robot using a visual and chemical Jacobian matrix are proposed. The basic idea behind the visual Jacobian matrix is modeling the differential relationship between the camera system and the robotic control system to detect and track accurately points of interest in confined environments. This approach allows the robot to easily detect and navigates to the QR code or seeks a gas source localization using surge cast algorithm. To track the QR code target, a visual servoing based on Jacobian matrix is used. For chemical servoing, three gas sensors are embedded on the hexapod. A Jacobian matrix applied to the gas concentration measurements allows estimating the direction of the main gas source. The effectiveness of the proposed scheme is first demonstrated on simulation. Finally, a hexapod prototype is designed and built and the experimental validation of the approach is presented and discussed.

Keywords: chemical servoing, hexapod robot, Jacobian matrix, visual servoing, navigation

Procedia PDF Downloads 98

Authors: Sitrapee Changmuenwai, Sudaratana Wongweragiat

Abstract:

It is important that a dry chemical fire extinguisher must be inspected for its readiness. For each inspection, the inspectors need to turn the fire extinguisher tank upside down to let the chemical inside the tank move and prevent solidification, which would make the tank not ready for usage when needed. Each tank weighs approximately 16 kg. The inspectors have to turn each tank upside down twice (2 minutes/round). They need to put the tanks over their shoulder close to their ear in order to hear the chemical flow inside the tank or use their hands to feel it. The survey and questionnaire 'The Questionnaire Know Body', which includes neck, left shoulder, upper and lower right arms suggest that all 12 security staffs have the same fatigues. The current dry chemical fire extinguisher inspection affects various ergonomic health problems. Rapid Entire Body Assessment (REBA) is used for evaluation of posture risks so that the working postures may be redesigned or corrected. The dry chemical fire extinguisher inspection equipment has been developed to reduce ergonomic health risks for the inspectors. A REBA analysis has been performed again, and the risk score has been decreased from 13 to 3. In addition, feedbacks from the first trial of the developed equipment show that there are demands to increase the installation in order to reduce the ergonomic health risks.

Keywords: dry chemical fire extinguisher inspection equipment, ergonomic, REBA, rapid entire body assessment

Procedia PDF Downloads 99

Authors: Amirhossein Hasani, Shamin Houshmand Sharifi

Abstract:

In this work, we investigate humidity sensing behavior of the graphene oxide with porous silicon substrate. By evaporation method, aluminum interdigital electrodes have been deposited onto porous silicon substrate. Then, by drop-casting method graphene oxide solution was deposited onto electrodes. The porous silicon was formed by electrochemical etching. The experimental results showed that using porous silicon substrate, we obtained two times larger sensitivity and response time compared with the results obtained with silicon substrate without porosity.

Keywords: graphene oxide, porous silicon, humidity sensor, electrochemical

Procedia PDF Downloads 578

Authors: Hamid Merzouk, D. T. Talantikite, H. Haddad, Amel Tounsi

Abstract:

ZnS is an important II-VI binary compound with large band-gap energy at room temperature. We present in this work preparation and characterization of ZnS and Cu doped ZnS thin films. The depositions are performed by a simple chemical bath deposition route. Structural properties are carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Optical transmittance is investigated by the UV-visible spectroscopy at room temperature.

Keywords: chemical, bath, method, Cu, doped, ZnS, thin, films

Procedia PDF Downloads 523

Authors: Hefzollah Mohammadiyan, Mohammad Bagher Heidari, Ensiyeh Hajeb

Abstract:

In this paper investigates and analyses the structure of nano sensors will be discussed. The structure can be classified based of nano sensors: quantum points, carbon nanotubes and nano tools, which details into each other and in turn are analyzed. Then will be fully examined to the Carbon nanotubes as chemical and mechanical sensors. The following discussion, be examined compares the advantages and disadvantages as different types of sensors and also it has feature and a wide range of applications in various industries. Finally, the structure and application of Chemical sensor transistors and the sensors will be discussed in air pollution control.

Keywords: carbon nanotubes, quantum points, chemical sensors, mechanical sensors, chemical sensor transistors, single walled nanotube (SWNT), atomic force microscope (AFM)

Procedia PDF Downloads 411

Authors: Ryan Villafuerte Lansangan

Abstract:

Assessing students’ understanding in the microscopic level of an abstract subject like chemistry poses a challenge to teachers. Literature reveals that the use of representations serves as an essential avenue of measuring the extent of understanding in the discipline as an alternative to traditional assessment methods. This undertaking explored the representational competence profile of high school students from the University of Santo Tomas High School in understanding selected chemical principles and correlate this with their academic profile in chemistry based on their performance in the academic achievement examination in chemistry administered by the Center for Education Measurement (CEM). The common misconceptions of the students on the selected chemistry principles based on their representations were taken into consideration as well as the students’ views regarding their understanding of the role of chemical representations in their learning. The students’ level of representation task instrument consisting of the main lessons in chemistry with a corresponding scoring guide was prepared and utilized in the study. The study revealed that most of the students under study are unanimously rated as Level 2 (symbolic level) in terms of their representational competence in understanding the selected chemical principles through the use of chemical representations. Alternative misrepresentations were most observed on the students’ representations on chemical bonding concepts while the concept of chemical equation appeared to be the most comprehensible topic in chemistry for the students. Data implies that teachers’ representations play an important role in helping the student understand the concept in a microscopic level. Results also showed that the academic achievement in the chemistry of the students based on the standardized CEM examination has a significant association with the students’ representational competence. In addition, the students’ responses on the students’ views in chemical representations questionnaire evidently showed a good understanding of what a chemical representation or a mental model is by drawing a negative response that these tools should be an exact replica. Moreover, the students confirmed a greater appreciation that chemical representations are explanatory tools.

Keywords: chemical representations, representational competence, academic profile in chemistry, secondary students

Procedia PDF Downloads 377

Authors: Y. Yulnafatmawita, H. Hermansah

Abstract:

Topography is a factor affecting soil characteristics. Chemical characteristics of a soil is a factor determining the productivity of the land. A research was conducted in Bukit Sarasah Padang, an area receiving > 5000 mm rainfall annually. The purpose of this research was to determine the chemical characteristics of soils at sequence topography in hill-slope of Bukit Sarasah. Soils were sampled at 3 different altitudes in the research area from 315 m – 515 m asl with 100 m interval. At each location, soil samples were taken from two depths (0-20 cm and 30-50 cm) for soil chemical characteristics (pH, CEC, organic-C, N-total, C/N, Ca-, Mg-, K-, Na-, Al-, and H-exchangeable). Based on the data resulted, it was found that there was a tendency of decreasing soil organic matter (SOC) content by increasing location from 315 to 515 m asl as well as from the top 0-20 cm to 30-50 cm soil depth. The same tendency was also found for the CEC, pH, N-total, and C/N ratio of the soil. On the other hand, exchangeable-Al and -H tended to increase by increasing elevation in Bukit Sarasah. There was no significant difference found for the concentration of exchangeable cations among the elevations and between the depths. The soil chemical characteristics on the top 20 cm were generally better than those on 30-50 cm soil depth, however, different elevation did not gave significant difference of the concentration.

Keywords: soil chemical characteristics, soil depths, topo-sequence, wet tropical area

Procedia PDF Downloads 448

Authors: B. R. Phanikumar, Sana Suri

Abstract:

Expansive soils swell when they absorb water and shrink when water evaporates from them. Hence, lightly loaded civil engineering structures found in these soils are subjected to severe distress. Therefore, there is a need to ameliorate or improve these swelling soils through some innovative methods. This paper discusses chemical stabilisation of expansive soils, a technique in which chemical reagents such as lime and calcium chloride are added to expansive soils to reduce the volumetric changes occurring in expansive soils and also to improve their engineering behaviour.

Keywords: expansive soils, swelling, shrinkage, amelioration, lime, calcium chloride

Procedia PDF Downloads 281

Authors: Deybith Venegas-Rojas, Sercan Keskin, Svenja Riekeberg, Sana Azim, Stephanie Manz, R. J. Dwayne Miller, Hoc Khiem Trieu

Abstract:

Liquid Transmission Electron Microscopy (TEM) is a growing area with a broad range of applications from physics and chemistry to material engineering and biology, in which it is possible to image in-situ unseen phenomena. For this, a nanofluidic device is used to insert the nanoflow with the sample inside the microscope in order to keep the liquid encapsulated because of the high vacuum. In the last years, Si3N4 windows have been widely used because of its mechanical stability and low imaging contrast. Nevertheless, the pressure difference between the inside fluid and the outside vacuum in the TEM generates bulging in the windows. This increases the imaged fluid volume, which decreases the signal to noise ratio (SNR), limiting the achievable spatial resolution. With the proposed device, the membrane is fortified with a microstructure capable of stand higher pressure differences, and almost removing completely the bulging. A theoretical study is presented with Finite Element Method (FEM) simulations which provide a deep understanding of the membrane mechanical conditions and proves the effectiveness of this novel concept. Bulging and von Mises Stress were studied for different membrane dimensions, geometries, materials, and thicknesses. The microfabrication of the device was made with a thin wafer coated with thin layers of SiO2 and Si3N4. After the lithography process, these layers were etched (reactive ion etching and buffered oxide etch (BOE) respectively). After that, the microstructure was etched (deep reactive ion etching). Then the back side SiO2 was etched (BOE) and the array of free-standing micro-windows was obtained. Additionally, a Pyrex wafer was patterned with windows, and inlets/outlets, and bonded (anodic bonding) to the Si side to facilitate the thin wafer handling. Later, a thin spacer is sputtered and patterned with microchannels and trenches to guide the nanoflow with the samples. This approach reduces considerably the common bulging problem of the window, improving the SNR, contrast and spatial resolution, increasing substantially the mechanical stability of the windows, allowing a larger viewing area. These developments lead to a wider range of applications of liquid TEM, expanding the spectrum of possible experiments in the field.

Keywords: liquid cell, liquid transmission electron microscopy, nanofluidics, nanofluidic cell, thin films

Procedia PDF Downloads 230

Authors: Amir Bahrami

Abstract:

In the fields of chemical graph theory, molecular topology, and mathematical chemistry, a topological index or a descriptor index also known as a connectivity index is a type of a molecular descriptor that is calculated based on the molecular graph of a chemical compound. Topological indices are numerical parameters of a graph which characterize its topology and are usually graph invariant. Topological indices are used for example in the development of quantitative structure-activity relationships (QSARs) in which the biological activity or other properties of molecules are correlated with their chemical structure. In this paper some descriptor index (descriptor index) of single-walled carbon nanotubes, is determined.

Keywords: chemical graph theory, molecular topology, molecular descriptor, single-walled carbon nanotubes

Procedia PDF Downloads 301

Authors: Rajat Dhawan, Hitendra K. Malik

Abstract:

Electronegative plasmas comprising electrons, positive ions, and negative ions are advantageous for their expanding applications in industries. In plasma cleaning, plasma etching, and plasma deposition process, electronegative plasmas are preferred because of relatively less potential developed on the surface of the material under investigation. Also, the presence of negative ions avoid the irregularity in etching shapes and also enhance the material working during the fabrication process. The interaction of metallic conducting surface with plasma becomes mandatory to understand these applications. A metallic conducting probe immersed in a plasma results in the formation of a thin layer of charged species around the probe called as a sheath. The density of the ions embedded on the surface of the material and the sheath thickness are the important parameters for the surface-plasma interaction. Sheath thickness will give rise to the information of affected plasma region due to conducting surface/probe. The knowledge of the density of ions in the sheath region is advantageous in plasma nitriding, and their temperature is equally important as it strongly influences the thickness of the modified layer during surface plasma interaction. In the present work, we considered a negatively biased metallic probe immersed in a warm electronegative plasma. For this system, we adopted the continuity equation and momentum transfer equation for both the positive and negative ions, whereas electrons are described by Boltzmann distribution. Finally, we use the Poisson’s equation. Here, we assumed the spherical geometry for small probe radius. Poisson’s equation reveals the behaviour of potential surrounding a conducting metallic probe along with the use of the continuity and momentum transfer equations, with the help of proper boundary conditions. In turn, it gives rise to the information about the density profile of charged species and most importantly the thickness of the sheath. By keeping in mind, the well-known Bohm-Sheath criterion, all calculations are done. We found that positive ion density decreases with an increase in positive ion temperature, whereas it increases with the higher temperature of the negative ions. Positive ion density decreases as we move away from the center of the probe and is found to show a discontinuity at a particular distance from the center of the probe. The distance where discontinuity occurs is designated as sheath edge, i.e., the point where sheath ends. These results are beneficial for industrial applications, as the density of ions embedded on material surface is strongly affected by the temperature of plasma species. It has a drastic influence on the surface properties, i.e., the hardness, corrosion resistance, etc. of the materials.

Keywords: electronegative plasmas, plasma surface interaction positive ion density, sheath thickness

Procedia PDF Downloads 110

Authors: Mohd Moiz Khan, S. M. Mahajani, G. N. Jadhav

Abstract:

Waste foundry sand (total clay content 15%) contains toxic heavy metals and particulate matter which make dumping of waste sand an environmental and health hazard. Disposal of waste foundry sand (WFS) remains one of the substantial challenges faced by Indian foundries nowadays. To cope up with this issue, the chemical method was used to reclaim WFS. A stirrer tank reactor was used for chemical reclamation. Experiments were performed to reduce the total clay content from 15% to as low as 0.9% in chemical reclamation. This method, although found to be effective for WFS reclamation, it may face a challenge due to the possibly high operating cost. Reclaimed sand was found to be satisfactory in terms of sand qualities such as total clay (0.9%), active clay (0.3%), acid demand value (ADV) (2.6%), loss on igniting (LOI) (3 %), grain fineness number (GFN) (56), and compressive strength (60 kPa). The experimental data generated on chemical reactor under different conditions is further used to optimize the design and operating parameters (rotation speed, sand to acidic solution ratio, acid concentration, temperature and time) for the best performance. The use of reclaimed sand within the foundry would improve the economics and efficiency of the process and reduce environmental concerns.

Keywords: chemical reclamation, clay content, environmental concerns, recycle, waste foundry sand

Procedia PDF Downloads 112

Authors: Maryam Shayan

Abstract:

Programming frameworks have been utilized as a part of chemical industry process safety operation and configuration to enhance its effectiveness. This paper gives a brief survey and investigation of the best in class and effects of programming frameworks in process security. A study was completed by talking staff accountable for procedure wellbeing practices in the Iranian chemical process industry and diving into writing of innovation for procedure security. This article investigates the useful and operational attributes of programming frameworks for security and endeavors to sort the product as indicated by its level of effect in the administration chain of importance. The study adds to better comprehension of the parts of Information Communication Technology in procedure security, the future patterns and conceivable gaps for innovative work.

Keywords: programming frameworks, chemical industry process, process security, administration chain, information communication technology

Procedia PDF Downloads 338

Authors: Junze Li, M. Li

Abstract:

Laser diodes fabricated from the III-nitride material system are emerging solutions for the next generation telecommunication systems and optical clocks based on Ca at 397nm, Rb at 420.2nm and Yb at 398.9nm combined 556 nm. Most of the applications require single longitudinal optical mode lasers, with very narrow linewidth and compact size, such as communication systems and laser cooling. In this case, the GaN based distributed feedback (DFB) laser diode is one of the most effective candidates with gratings are known to operate with narrow spectra as well as high power and efficiency. Given the wavelength range, the period of the first-order diffraction grating is under 100 nm, and the realization of such gratings is technically difficult due to the narrow line width and the high quality nitride overgrowth based on the Bragg grating. Some groups have reported GaN DFB lasers with high order distributed feedback surface gratings, which avoids the overgrowth. However, generally the strength of coupling is lower than that with Bragg grating embedded into the waveguide within the GaN laser structure by two-step-epitaxy. Therefore, the overgrowth on the grating technology need to be studied and optimized. Here we propose to fabricate the fine step shape structure of first-order grating by the nanoimprint combined inductively coupled plasma (ICP) dry etching, then carry out overgrowth high quality AlGaN film by metalorganic chemical vapor deposition (MOCVD). Then a series of gratings with different period, depths and duty ratios are designed and fabricated to study the influence of grating structure to the nano-heteroepitaxy. Moreover, we observe the nucleation and growth process by step-by-step growth to study the growth mode for nitride overgrowth on grating, under the condition that the grating period is larger than the mental migration length on the surface. The AFM images demonstrate that a smooth surface of AlGaN film is achieved with an average roughness of 0.20 nm over 3 × 3 μm2. The full width at half maximums (FWHMs) of the (002) reflections in the XRD rocking curves are 278 arcsec for the AlGaN film, and the component of the Al within the film is 8% according to the XRD mapping measurement, which is in accordance with design values. By observing the samples with growth time changing from 200s, 400s to 600s, the growth model is summarized as the follow steps: initially, the nucleation is evenly distributed on the grating structure, as the migration length of Al atoms is low; then, AlGaN growth alone with the grating top surface; finally, the AlGaN film formed by lateral growth. This work contributed to carrying out GaN DFB laser by fabricating grating and overgrowth on the nano-grating patterned substrate by wafer scale, moreover, growth dynamics had been analyzed as well.

Keywords: DFB laser, MOCVD, nanoepitaxy, III-niitride

Procedia PDF Downloads 151

Authors: Paulos Meles Yihdego

Abstract:

To address the environmental impact of the cement industry and road building waste, the use of chemical stabilizers in conjunction with recycled asphalt and cement components was investigated. The silica-based chemical stabilizers and their potential effects on the base layer stabilized by cement are discussed in this paper. Strength, moisture compaction interaction, and microstructural characteristics are all examined. According to the outcome, using this stabilizer has improved the mechanical properties. The inclusion of chemical stabilizers in the combination, which is responsible for the mixture's improved strength, raised the intensity of the C-S-H (Calcium Silicate Hydrate) gel, according to a microstructural study. The design was demonstrated to be durable by the little ettringites found in the later phases. The application of this stabilizer ensures a strong, eco-friendly, durable base layer.

Keywords: ettringites, microstructure analysis, durability properties, cement stabilized base

Procedia PDF Downloads 33

Authors: Rachael Olatoun Okunuga

Abstract:

Developing young people’s employability is a key policy issue for ensuring their successful transition to the labour market and their access to career oriented employment. The youths of today irrespective of their gender need to acquire the knowledge, skills and attitudes that will enable them to create or find jobs as well as cope with unpredictable labour market changes throughout their working lives. In a study carried out to determine the influence of gender on job-competencies requirements of chemical-based industries and undergraduate-competencies acquisition by chemists working in the industries, all chemistry graduates working in twenty (20) chemical-based industries that were randomly selected from six sectors of chemical-based industries in Lagos and Ogun States of Nigeria were administered with Job-competencies required and undergraduate-competencies acquired assessment questionnaire. The data were analysed using means and independent sample t-test. The findings revealed that the population of female chemists working in chemical-based industries is low compared with the number of male chemists; furthermore, job-competencies requirements are found not to be gender sensitive while there is no significant difference in undergraduate-competencies acquisition of male and female chemists. This suggests that females should be given the same opportunity of employment in chemical-based industries as their male counterparts. The study also revealed the level of acquisition of undergraduate competencies as related to the needs of chemical-based industries.

Keywords: knowledge, skill, attitude, acquired, required, employability

Procedia PDF Downloads 347

Authors: Aminu Musa Muhammad, Muhammad Kabiru Abubakar

Abstract:

Monthly changes in Phytoplankton periodicity, nutrient levels, temperature, pH, suspended solids, dissolved solids, conductivity, dissolved oxygen and biochemical oxygen demand of Kazaure Dam, Jigawa State, Nigeria were studied for a period of six months (July-Dec.-2011). Physico-chemical result showed that temperature and pH ranged between17-25˚C and 5.5-7.5, while dissolved solids and suspended solids ranged between 95-155 mg/L and 0.13-112 mg/L respectively. Dissolved oxygen (DO), Biochemical oxygen demand (BOD), Chemical oxygen demand (COD), conductivity, nitrate, phosphate and sulphate ion concentrations were within the ranges of 3.5-3.6 mg/L, 4.8-7.2 mg/L, 8.10-12.30 mg/L, 21-58µΩ/cm, 0.2-8.1 mg/L, 2.4-18.1 mg/L, and 1.22-15.60 mg/L respectively. A total of 4514 Org/L phytoplankton were recorded, of which four classes of algae were identified. These comprised of Chlorophyta (44.1%), Cyanophyta(30.62%), Bacillariophyta(3.2%), Euglenophyta (32.1%). Descriptive statistics of the result showed that phytoplankton count varied with variation of physico-chemical parameters at 5% level during the study period. The abundance and distribution of the algae varied with the variation in the physico-chemical parameters. Pearson correlation showed that temperature and nutrients were significantly correlated with phytoplankton, while DO, sulphate and pH were insignificantly correlated, while there was no significant correlation with COD and phytoplankton.

Keywords: correlation, phytoplankton, physico chemical, kazaure dam

Procedia PDF Downloads 519

Authors: Asibor Godwin, Adeniyi Funsho

Abstract:

This study was carried out to investigate the impact of biological treated effluent on the physico-chemical properties of receiving waterbodies and also to establish its suitability for other purposes. It focused on the changes of some physic-chemical variables as one move away from the point of discharge downstream of the waterbodies. Water samples were collected from 14 sampling stations made up of the untreated effluent, treated effluent and receiving streams (before and after treated effluent discharge) over a period of 6 months spanning the dry and rainy seasons. Analyses were carried out on the following: temperature, turbidity, pH, conductivity, major anions and cation, dissolved oxygen, percentage oxygen Saturation, biological oxygen demand (BOD), solids (total solids, suspended solids and dissolved solids), nitrates, phosphates, organic matter and flow discharge using standard analytical methods. The relationships between investigated sites with regards to their physico-chemical properties were analyzed using student-t statistics. Also changes in the treated effluent receiving streams after treated effluent outfall was discussed fully. The physico-chemical water quality of the receiving water bodies meets most of the general water requirements for both domestic and industrial uses. The untreated effluent quality was shown to be of biological origin based on the biological oxygen demand, chloride, dissolved oxygen, total solids, pH and organic matter. The treated effluent showed significant improvement over the raw untreated effluent based on most parameters assessed. There was a significant difference (p<0.05) between the physico-chemical quality of untreated effluent and the treated effluent for the most of the investigated physico-chemical quality. The difference between the discharged treated effluent and the unimpacted section of the receiving waterbodies was also significant (p<0.05) for the most of the physico-chemical parameters.

Keywords: eflluent, Opa River, physico-chemical, waterbody

Procedia PDF Downloads 236

Authors: J. S. S. Neto, R. A. A. Lima, D. K. K. Cavalcanti, J. P. B. Souza, R. A. A. Aguiar, M. D. Banea

Abstract:

In the last decade, investments in sustainable processes and products have gained space in several segments, such as in the civil, automobile, textile and other industries. In addition to increasing concern about the development of environmentally friendly materials that reduce, energy costs and reduces environmental impact in the production of these products, as well as reducing CO2 emissions. Natural fibers offer a great alternative to replace synthetic fibers, totally or partially, because of their low cost and their renewable source. The purpose of this research is to study the effect of surface chemical treatment on the thermal properties of hybrid fiber reinforced natural fibers (NFRC), jute + ramie, jute + sisal, jute + curauá, and jute fiber in polymer matrices. Two types of chemical treatment: alkalinization and silanization were employed, besides the condition without treatment. Differential scanning calorimetry (DSC), thermogravimetry (TG) and dynamic-mechanical analysis (DMA) were performed to explore the thermal stability and weight loss in the natural fiber reinforced composite as a function of chemical treatment.

Keywords: chemical treatment, hybrid composite, jute, thermal

Procedia PDF Downloads 289

Authors: Deybith Venegas-Rojas, Jens Budde, Dominik Nörz, Manfred Jücker, Hoc Khiem Trieu

Abstract:

Microfluidics is a promising approach for biomedicine cell culture experiments with microfluidic bioreactors (MBR), which can provide high precision in volume and time control over mass transport and microenvironments in small-scale studies. Nevertheless, shear stress and oxygen concentration are important factors that affect the microenvironment and then the cell culture. It is presented a novel MBR design in which differences in geometry, shear stress, and oxygen concentration were studied and optimized for cell culture. The aim is to mimic the in vivo condition with biocompatible materials and continuous perfusion of nutrients, a healthy shear stress, and oxygen concentration. The design consists of a capture system of PDMS micropillars which keep cells in place, so it is not necessary any hydrogel or complicated scaffolds for cells immobilization. Besides, the design allows continuous supply with nutrients or even any other chemical for cell experimentation. Finite element method simulations were used to study and optimize the effect of parameters such as flow rate, shear stress, oxygen concentration, micropillars shape, and dimensions. The micropillars device was fabricated with microsystem technology such as soft-lithography, deep reactive ion etching, self-assembled monolayer, replica molding, and oxygen plasma bonding. Eight different geometries were fabricated and tested, with different flow rates according to the simulations. During the experiments, it was observed the effect of micropillars size, shape, and configuration for stability and shear stress control when increasing flow rate. The device was tested with several successful HepG2 3D cell cultures. With this MBR, the aforementioned parameters can be controlled in order to keep a healthy microenvironment according to specific necessities of different cell types, with no need of hydrogels and can be used for a wide range of experiments with cells.

Keywords: cell culture, micro-bioreactor, microfluidics, micropillars, oxygen concentration, shear stress

Procedia PDF Downloads 262

Authors: Fatima Benchikh-Amiraa, Hocine Laouerb, Smain Amiraa, Guido Flaminic

Abstract:

The essential oils of the aerial parts of Lavandula multifida and L. stoechas were extracted at the full bloom stage by hydrodistillation and theirs chemical compositions were estimated by means of gas chromatography–mass spectrometry (GC–MS). A total of 46 and 67 constituents were identified representing 95.5% and 98.2% of the total oils, respectively. The main components of L. multifida oil were carvacrol (63.8%), beta-bisabolene (8.7%), spathulenol (6.2%), caryophyllene oxide (3.6%) and linalool (2.9%). The oil of L. stoechas was dominated by fenchone (63.9%), camphor (7.8%), 1,8-cineole (5.3%) and myrtenyl acetate (4.2).

Keywords: essential oils, Lavandula multifida, Lavandula stoechas, chemical and molecular engineering

Procedia PDF Downloads 380

Authors: Asif Jan

Abstract:

Sodium hypochlorite (NaClO) is a common cleaning agent for ultrafiltration (UF) membranes. While its detrimental effects on polymeric membranes are well-documented, its impact on ceramic membranes remains less explored. This study investigates the chemical stability of silicon carbide (SiC) UF membranes prepared using low-pressure chemical vapor deposition (LP-CVD) during prolonged NaClO exposure. SiC UF membranes were fabricated via LP-CVD at two different temperature and pressure conditions. LP-CVD offers the advantage of SiC membrane fabrication at significantly lower temperatures (700-900°C) compared to conventional methods. The membranes were subjected to 200 hours of NaClO aging to assess their resilience. Before and after aging, we evaluated the properties and performance of the SiC UF membranes to identify optimal LP-CVD conditions. Our findings show that SiC UF membranes produced at 860°C via LP-CVD exhibit exceptional resistance to NaClO aging, whereas those prepared at 750°C experience significant deterioration. This highlights the crucial role of precise LP-CVD parameters in ensuring the robustness and long-term performance of SiC membranes in harsh chemical cleaning environments.

Keywords: ceramic membranes, ultrafiltration membranes, wastewater treatment, chemical vapor deposition

Procedia PDF Downloads 41

Authors: Elackiya Sithamparanathan

Abstract:

Chemical agents used during the Sri Lankan civil war continue to threaten human and environmental health as affected areas are re-settled. Bioremediation is a cost-effective and eco-friendly approach to degrading chemical agents, and has greater public acceptance than chemical degradation. Baseline data on contaminant distribution, environmental parameters, and indigenous microbes are required before bioremediation can commence. The culture and isolate of suitable microbes and enzymes should be followed by laboratory trials, before field application and long-term monitoring of contaminant concentration, soil parameters, microbial ecology, and public health to monitor environmental and public health. As local people are not aware of the persistence of warfare chemicals and do not understand the potential impacts on human health, community awareness programs are required. Active community participation, and collaboration with international and local agencies, would contribute to the success of bioremediation and the effective removal of chemical agents in war affected areas of Sri Lanka.

Keywords: bioremediation, environmental protection, human health, war affected regions in Sri Lanka

Procedia PDF Downloads 348

Authors: Guillaume Caulier, Lola Brasseur, Patrick Flammang, Pascal Gerbaux, Igor Eeckhaut

Abstract:

Saponins and quinones are two major groups of secondary metabolites widely distributed in the biosphere. More specifically, triterpenoid saponins and anthraquinones are mainly found in a wide variety of plants, bacteria and fungi. In the animal kingdom, these natural organic compounds are rare and only found in small quantities in arthropods, marine sponges and echinoderms. In this last group, triterpenoid saponins are specific to holothuroids (sea cucumbers) while anthraquinones are the chemical signature of crinoids (feather stars). Depending on the species, they present different molecular cocktails. Despite presenting different chemical properties, these molecules share numerous similarities. This study compares the biological distribution, the pharmacological effects and the ecological roles of holothuroid saponins and crinoid anthraquinones. Both of them have been defined as allomones repelling predators and parasites (i.e. chemical defense) and have interesting pharmacological properties (e.g. anti-bacterial, anti-fungal, anti-cancer). Our study investigates the chemical ecology of two symbiotic associations models; between the snapping shrimp Synalpheus stimpsonii associated with crinoids and the Harlequin crab Lissocarcinus orbicularis associated with holothuroids. Using behavioral experiments in olfactometers, chemical extractions and mass spectrometry analyses, we discovered that saponins and anthraquinones present a second ecological role: the attraction of obligatory symbionts towards their hosts. They can, therefore, be defined as kairomones. This highlights a new paradigm in marine chemical ecology: Chemical repellents are attractants to obligatory symbionts because they constitute host specific chemical signatures.

Keywords: anthraquinones, kairomones, marine symbiosis, saponins, attractant

Procedia PDF Downloads 169

Authors: Ahmed O. Apampa, Yinusa A. Jimoh

Abstract:

The paper examines the mechanism of pozzolan-soil reactions, using a recent study on the chemical stabilization of a Class A-2-7 (3) lateritic soil, with corn cob ash (CCA) as case study. The objectives are to establish a nexus between cation exchange capacity of the soil, the alkaline forming compounds in CCA and percentage CCA addition to soil beyond which no more improvement in strength properties can be achieved; and to propose feasible chemical reactions to explain the chemical stabilization of the lateritic soil with CCA alone. The lateritic soil, as well as CCA of pozzolanic quality Class C were separately analysed for their metallic oxide composition using the X-Ray Fluorescence technique. The cation exchange capacity (CEC) of the soil and the CCA were computed theoretically using the percentage composition of the base cations Ca²⁺, Mg²⁺ K⁺ and Na²⁺ as 1.48 meq/100 g and 61.67 meq/100 g respectively, thus indicating a ratio of 0.024 or 2.4%. This figure, taken as the theoretical amount required to just fill up the exchangeable sites of the clay molecules, compares well with the laboratory observation of 1.5% for the optimum level of CCA addition to lateritic soil. The paper went on to present chemical reaction equations between the alkaline earth metals in the CCA and the silica in the lateritic soil to form silicates, thereby proposing an extension of the theory of mechanism of soil stabilization to cover chemical stabilization with pozzolanic ash only. The paper concluded by recommending further research on the molecular structure of soils stabilized with pozzolanic waste ash alone, with a view to confirming the chemical equations advanced in the study.

Keywords: cation exchange capacity, corn cob ash, lateritic soil, soil stabilization

Procedia PDF Downloads 208

Authors: Azizul Haque, Kamrun Nahar

Abstract:

Field experiments were conducted to reduce the chemical fertilizers with the integrated use of straight and phospho- vermicompost with chemical fertilizers in T. aman-Boro rice cropping pattern at the BINA farm, Mymensingh during 2019-20. Six treatments were used in the experiment for both the crops. The treatments used for T. aman rice (Binadhan 17) with straight vermicompost were as follows: T1: Native soil fertility, T2: 100% N from Chemical Fertilizer (CF), T3:70%N from CF, T4: 30% N from vermicompost-3 + 70% N from CF and T5:30% N from vermicompost-4 + 70% N from CF and T6: 100% PKS only. The treatments of Boro rice (var. Binadhan -10) with phospho-vermicompost were: T1: Native soil fertility, T2: 100% NPKS from chemical fertilizer (CF), T3:75% NKS from CF (Non IPNS) with 1 t ha-1 Phospho-vermicompost (P-Vermicom), T4: 100% NKS (IPNS) with 2 t ha-1 P-Vermicom, T5: 100% NKS from CF (Non IPNS) with 2 t ha-1 P-Vermicom and T6: 100% NKS. The experiments were conducted in a Randomized Complete Block Design with three replications. The treatment T5 (5.5 t ha-1) gave maximum grain yield of T.aman rice followed by the treatment T4 (5.4 t ha-1). But the treatmentsT5, T4, and T2 gave identical grain yields of T. aman rice. Similar results were observed in case of straw yields of T. Aman rice. The result indicated that 70% N from CF with 30% N from either straight vermicompost-3 or straight vermicompost-4 gave comparable yield to the sole application of 100% N from CF alone. Therefore, 30% chemical fertilizers (N, P, K and S) could be saved with the integrated (IPNS) use of vermicompost-3 or vermicompost-4 in the cultivation of T. aman rice. Application of Phospho-vermicompost significantly influenced the yield and yield contributing characters of Boro rice (Binadhan-10). The treatment T4 (7.23.0 t ha-1) gave maximum grain yield of Boro rice followed by the treatments T2 and T5. But the treatments T2 and T5 produced statistically similar grain yields. The results from the treatment T4 (100% NKS (IPNS) with 2.0 t ha-1P-Vermicom) indicated that full demand of P could be met up from 2 t ha-1 Phospho-vermicompost with IPNS chemical fertilizers (NKS) which was sufficient for attaining the highest grain yield of Boro rice than that of the treatment T2 (100% NPKS from CF) and the treatmentT5 (100% NKS from CF (Non IPNS) + 2 t ha-1 Phospho-vermicompost). The results revealed that 100% P and substantial amount of N (21%), K (44.6%) and S (53.7%) fertilizers could be saved with the integrated use of Phospho-vermicompost in the cultivation of Boro rice. In case of Boro rice partial cost benefit analysis showed that the application of Phospho-vermicompost (@2 tha--1) with IPNS chemical fertilizes (NKS) gave higher return of Tk. 18,213 / - than that of only 100% chemical fertilizer. Therefore, use of Phospho-vermicompost was beneficial for the cultivation of Boro rice in combination with suitable dose of chemical fertilizers.

Keywords: phosphovermicompost, cropping pattern, rice yield, chemical fertilizer

Procedia PDF Downloads 77

Authors: Vasant Reddy, Shivani A. Singh, Pravin S. More

Abstract:

In the present investigation, we demonstrated the fabrication of few-layers of graphene sheets with alkali metal i.e. Rb-G using chemical route method. The obtained materials were characterized by means of chemical, structural and electrical techniques, using the ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and 4 points probe, respectively. The XRD studies were carried out to understand the phase of the samples where we found a sharp peak of Rb-G at 26.470. UV-Spectroscopy of Graphene and Rb-modified graphene samples shows the absorption peaks at ~248 nm and ~318 nm respectively. These analyses show that this modified material can be useful for gas sensing applications and to be used in diverse areas.

Keywords: chemical route, graphene, gas sensing, UV-spectroscopy

Procedia PDF Downloads 227