Tribological characteristics of coatings on aluminium and its alloys

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Hard anodising on aluminium and its alloys has been widely practised for many years in order to improve the resistance of the otherwise poor wear characteristics of aluminium. In recent years there has been an increasing interest in other treatments and coatings, on both aluminium and other base metals. The aim of this investigation is to explain the tribological performance and wear mechanism(s) of an uncoated aluminium alloy, four anodic coated alloys, and also an electroless nickel alloy. All of the coatings are produced on three different aluminium alloys. The thickness of the anodic films is 30-35 micron, as this thickness falls within the range commonly used by industry. In an endeavour to explain the role of coating thickness on wear life, electroless nickel alloy has been produced in a range of thicknesses of 10, 20 and 30 micron. To evaluate abrasive and adhesive wear, the samples were rubbed against a single point diamond and steel ball, respectively, in a reciprocating movement at room temperature and 65-75% relative humidity, under a wide range of load and sliding distance. Some tests continued to run until a breakdown of the coatings occurred, whilst other tests were interrupted at intermediate stages. This enabled the initiation and propagation of failure mechanisms to be studied. Abrasive wear was performed under dry conditions, whereas, adhesive wear was evaluated under both dry and lubricated conditions. Wear of these coatings was proportional to the applied load and sliding distance, but there was no direct relationship between wear and hardness. The tribological performance of these coatings appears to be dictated by a) the composition of the substrate, b) the chemical and physical nature of the coatings and c) the test conditions. Under boundary lubricated conditions there was a considerable increase in the wear life of the coatings. A three dimensional surface texture is superior to a machined surface, in controlling contact conditions. There is an approximate linear relationship between coating thickness and wear life for electroless nickel alloys. These coatings predominantly fail by adhesion, plastic deformation and brittle fracture. A microscopic model for fracture of brittle materials, under both static and dynamic conditions for abrasive and adhesive wear correlates very well with the behaviour of these coatings. Analytical interpretation of adhesive wear was made by separately calculating the coefficient of wear "K" of the counterbodies. This information enables an improved understanding of the wear test itself to be added to the model of the wear mechanisms involved

The Doha model of organ donation and transplantation: thinking beyond citizenship

This paper reviews the policy and practice of organ donation and transplantation in Qatar that has developed since January 2011. The important features of the Doha Model (the ‘Model’) are explored, including: (i) all legal residents of Qatar have an equal right to access deceased donor organs and transplantation regardless of their citizenship status; (ii) no prioritisation in organ allocation is given to Qatari citizens; (iii) a multilingual and multicultural education and promotional program about donation has been implemented to engage the diverse national communities resident within Qatar; (iv) financial incentives or fungible rewards for living or deceased donation are prohibited. The ethical framework of this policy will be examined in the light of the national self-sufficiency paradigm, which advocates reciprocity and solidarity among resident populations seeking to meet all needs for transplantation equitably. We review some preliminary evidence of the impact of the Model with respect to engagement of a highly diverse multinational population in a donation and transplantation program, and argue that the Model may inform policy and practice in other countries, particularly those with non-citizen resident populations

Cloud Storage Protection Scheme Based on Fully Homomorphic Encryption

Cloud computing allows enterprises and individuals to have a less physical infrastructure of software and hardware. Nevertheless, there are some concerns regarding privacy protection which may turn out to be a strong barrier. Traditional encryption schemes have been used to encrypt the data before sending them to the cloud. However, the private key has to be provided to the server before any calculations on the data. To solve this security problem, this paper proposes a fully homomorphic encryption scheme for securing cloud data at rest. The scheme is based on prime modular operation, its security depends on factoring multiple large prime numbers (p1, p2,...pn) up to n, which is formed from very large prime numbers up to hundreds of digits as this is an open problem in mathematics. In addition, the elements of the secret key are derived from a series of mathematical operations and the calculation of an Euler coefficient within the modular of integers. Furthermore, it adds the complexity of noise to the plaintext using the number of users of the Cloud Service Provider. Moreover, its randomness is evaluated by the National Institute of Standards and Technology statistical tests, and the results demonstrating that the best statistical performance was obtained with this algorithm

Physical Layer Security using Time-Reversal Pre-Coding based OFDM-DCSK Communication System with Artificial Noise Injection

In this paper, Time-Reversal (TR) pre-coding with Artificial Noise (AN) injection is proposed to enhance the physical layer security (PLS) performance in orthogonal Frequency Division Multiplexing-Differential Chaos Shift Keying (OFDM-DCSK) system, which is named the TRAN-OFDM-DCSK system. This approach is provided to achieve high data rates, high PL data security, and high reliability performance. The AN signal does not spoil the transmitted data to the genuine receiver, but it reduces the ungenuine detection performance. This system ensures the secrecy of communication to the genuine receiver when the sender knows the Channel State Information (CSI) of the genuine communication link. Still, the information about the instantaneous CSI of a possible eavesdropper does not know the transmitter. The performance of the proposed TRAN-OFDM-DCSK system is investigated and tested under a Flat Rayleigh Fading Channel (FRFC). An approach is provided for calculating the performance of Bit Error Rate (BER), and the expression of BER analytical is derived and compared with the simulation version. Furthermore, the ergodic Secrecy Rate (SR) is derived and analyzed at the genuine and ungenuine receivers over the FRFC. Our result shows the best performance for the genuine receiver compared with ungenuine receiver regarding secrecy performance for BER and SR

Photonic Crystal Fiber Pollution Sensor Based on the Surface Plasmon Resonance Technology

تم اقتراح الألياف البلورية الضوئية (PCF) بناءً على تأثير رنين البلازمون السطحي (SPR) للكشف عن عينات المياه الملوثة. يتم توضيف خصائص الاستشعار باستخدام طريقة العناصر المحدودة. الفجوة على الجانب الأيمن من قلب PCF مطلية بمادة الذهب المستقرة كيميائيًا لتحقيق عملية الاستشعار. تم فحص معلمات أداء المستشعر المقترح من حيث حساسية الطول الموجي ، وحساسية السعة ، ودقة المستشعر ، والعلاقة الخطية لطول  موجة الرنين مع تغيرفي  معامل الانكسار العينات . في نطاق الاستشعار من 1.33 إلى 1.3624 ، تم تحقيق اقصى حساسية بلغت  1360.2 nm ∕ RIU  و  1184 RIU−مع دقة مستشعر عالية بلغت 7 ×10-5 RIU  و5.4× 10−5  باستخدام طرق التحقيق  كالطول الموجي والسعة على التوالي. يمكن تصنيع المستشعر المقترح لإكتشاف الملوثات في المياه  عن طريق ايجاد معاملات انكسارها  .Photonic Crystal Fiber (PCF) based on the Surface Plasmon Resonance (SPR) effect has been proposed to detect polluted water samples. The sensing characteristics are illustrated using the finite element method. The right hole of the right side of PCF core has been coated with chemically stable gold material to achieve the practical sensing approach. The performance parameter of the proposed sensor is investigated in terms of wavelength sensitivity, amplitude sensitivity, sensor resolution, and linearity of the resonant wavelength with the variation of refractive index of analyte. In the sensing range of 1.33 to 1.3624, maximum sensitivities of 1360.2 nm ∕ RIU and 184 RIU−1 are achieved with the high sensor resolutions of 7 ×10-5 RIU and 5.4× 10−5 RIU using wavelength and amplitude interrogation methods, respectively. The proposed sensor could be established to detect various refractive index (RI) of pollutions in water

CHEMICAL STRUCTURE OPTIMIZATION OF LUPEOL AS ER-Α AND HER2 INHIBITOR

Objectives: Lupeol, a triterpenoid isolated from Kasturi (Mangifera casturi) fruit has been known for having several pharmacological activities, including anticancer properties. Lupeol showed antiproliferative activity toward many cancer cells line including breast cancer. Lupeol showed promising potency as both ER-α and HER2 inhibitors, although still lower than known ER-α and HER2 Inhibitors. Chemical structure optimization of lupeol was predicted could increase the affinity of lupeol derivatives against ER-α and HER2. This study aims to determine lupeol derivative with the highest affinity against ER-α and HER2.Methods: All ligands were sketched and optimized using Gaussian 03W with Hartree–Fock method basis set 3-21G. Molecular docking was performed using Autodock 4.2.6 on several modified chemical structure of lupeol against active site of ER-α and HER2. The main parameter used was the free energy of binding and inhibition constants as affinity marker.Results: The docking results show that lupeol derivative with an amine group (Lupeol-2) and ethyl group (Lupeol-4) at position C3 provide the highest affinity with the free energy of binding and dissociation constant −12.24 kcal/mol and 1.07 nM for ER-α also −9.63 kcal/mol and 86.94 nM for HER2, respectively. Interestingly, although lupeol derivatives showed higher affinity toward ER-α, their amino acid residues were closer to the interaction on HER2.Conclusion: These results predict that lupeol have greater potential to be developed as a HER2 inhibitor. Further, derivate lupeol-4 should be potential to be developed as HER2-positive breast cancer therapy

MAT-736: DEVELOPMENT OF HIGH STRENGTH NANO-SILICA MODIFIED RUBBERCRETE

Several research works have been carried out to study properties of concrete containing crumb rubber (rubbercrete) as a partial replacement to fine aggregate. Rubbercrete exhibits numerous benefits compared to conventional concrete such as lower in density, increased ductility, enhanced plastic capacity, higher toughness, higher impact resistance, better chloride penetration, lower thermal conductivity, higher noise reduction factor and better electrical resistivity. It has also been known to have better energy dissipation, durability and damping ratio. However, the main drawbacks of rubbercrete are decreasing in strengths and Young\u27s modulus. Therefore, to improve strengths of the rubbercrete, the crumb rubber has been pre-coated with nano-silica. Results have revealed that nano-silica modified rubbercrete can be produced with high strengths due to the densification of the interfacial transition zone (ITZ) and refining pore system of the rubbercrete

ANTIBACTERIAL ACTIVITY OF AKAR KUNING (ARCANGELISIA FLAVA) SECONDARY METABOLITES: MOLECULAR DOCKING APPROACH

Objectives: Akar kuning (Arcangelisia flava) was known to have various pharmacological activities including as antibacterial. Several Gram-positive and Gram-negative bacteria show response to akar kuning secondary metabolites, although the type of metabolites that inhibit the growth of each type of bacteria not yet known. This study aims to obtain the prediction of metabolites from akar kuning with the greatest antibacterial potential against various types of antibacterial receptors.Methods: Molecular docking was performed using Autodock Vina 1.1.2 on several secondary metabolites of akar kuning against active site of several antibacterial receptors that were known for many antibiotics including as cell wall, protein, nucleic acid synthesis inhibitors, and antimetabolites. The main parameter used was the free energy of binding as affinity marker.Results: The docking results show that among 11 metabolites studied, 6-hydroxyfibraurin, berberine, and fibleucin provided the lowest free energy of binding between 11 antibacterial receptors compared with natural substrates or inhibitors from each receptor. Interesting results show by berberine as inhibitor of protein synthesis with possibility of allosteric site discovery. Berberine also shows more than 75% similarity with natural substrate of cell wall inhibition receptor, indicating possible similar type of interaction.Conclusion: Overall, it seems that for the selected secondary metabolites of akar kuning, the main mechanism of action was the inhibition of protein and cell wall synthesis, which was shown by berberine

Faktor-faktor yang Berhubungan dengan Penggunaan Bucket Latrine pada Masyarakat Kelurahan Bagan Deli Kecamatan Medan Belawan Tahun 2013

One of the health effort the society is preparing the facilities basic sanitation. Latrine healthy is an important part in preventing transmission of infection diseases originating from feces. For it, important to reck the factors associated with the use of latrines.This study aims to determine the factors associated with the utilization of latrine bucket at the Village Deli Sub Chart Medan Belawan in 2013.This type of research is a cross sectional analytic design. The population in this study were 393 families who have a latrine bucket with a sample of 100 respondents is by systematic sampling methods. Statistical test used was exact fisher test with confidence level p <0.05. This study aimed to determine the factors associated with the utilization of the bucket latrine in the Village Deli Sub Terrain Chart Belawan. The research method used is analytic cross sectional design. The sample was a family who has a latrine bucket of 100 respondents, results showed that the variables that have a relationship with the utilization of the bucket latrine is knowledge (P = 0.001), attitude (P = 0.012), education (P = 0.001), the condition of latrines (P = 0.001), water supply (P = 0.020) health (P = 0.001), and the role of community leaders (P = 0.001). Statistical analysis using exact fisher test. Conclusions of this study are all factors that have a relationship with the utilization of latrine bucket at the Village Deli Sub Chart Medan Belawan, namely knowledge, attitudes, education, latrine conditions, the role of health workers and the role of community leaders. It is therefore recommended need increased knowledge, improvement bucket latrine conditions, availability of clean water, as well as an increase in the role of health workers and community leaders in order to increase the utilization of latrine bucket