Halogenation of SiC for band-gap engineering and excitonic functionalization

The optical excitation spectra and excitonic resonances are investigated in systematically functionalized SiC with Fluorine and/or Chlorine utilizing density functional theory in combination with many-body perturbation theory. The latter is required for a realistic description of the energy band-gaps as well as for the theoretical realization of excitons. Structural, electronic and optical properties are scrutinized and show the high stability of the predicted two-dimensional materials. Their realization in laboratory is thus possible. Huge band-gaps of the order of 4 eV are found in the so-called GW approximation, with the occurrence of bright excitons, optically active in the four investigated materials. Their binding energies vary from 0.9 eV to 1.75 eV depending on the decoration choice and in one case, a dark exciton is foreseen to exist in the fully chlorinated SiC. The wide variety of opto-electronic properties suggest halogenated SiC as interesting materials with potential not only for solar cell applications, anti-reflection coatings or high-reflective systems but also for a possible realization of excitonic Bose-Einstein condensation

The Mystique of Customers’ Saturation in Online Brand Communities

Most research studies in the area of online brand communities have largely studied the positive aspects of online brand communities, ignoring the negative influences, mainly the growing threat from customers’ saturation within these communities. Given the lack of understanding on the concept of customer saturation in online brand communities, this study establishes the necessary early understanding on this important concept by combining various streams of marketing and brand literature as well as information system. This study enhances understanding through the development of five propositions focusing on the role of customers’ saturation on (1) customers’ experience within online brand communities, (2) brand relationship, and (3) the co‐creation of value. The discussion and review of the current literature produces five important propositions. The propositions develop the direction that customer saturation in online brand communities is likely to impact three key areas

Dynamic sorted neighborhood indexing for real-time entity resolution

Real-time Entity Resolution (ER) is the process of matching query records in subsecond time with records in a database that represent the same real-world entity. Indexing techniques are generally used to efficiently extract a set of candidate records from the database that are similar to a query record, and that are to be compared with the query record in more detail. The sorted neighborhood indexing method, which sorts a database and compares records within a sliding window, has been successfully used for ER of large static databases. However, because it is based on static sorted arrays and is designed for batch ER that resolves all records in a database rather than resolving those relating to a single query record, this technique is not suitable for real-time ER on dynamic databases that are constantly updated. We propose a tree-based technique that facilitates dynamic indexing based on the sorted neighborhood method, which can be used for real-time ER, and investigate both static and adaptive window approaches. We propose an approach to reduce query matching times by precalculating the similarities between attribute values stored in neighboring tree nodes. We also propose a multitree solution where different sorting keys are used to reduce the effects of errors and variations in attribute values on matching quality by building several distinct index trees. We experimentally evaluate our proposed techniques on large real datasets, as well as on synthetic data with different data quality characteristics. Our results show that as the index grows, no appreciable increase occurs in both record insertion and query times, and that using multiple trees gives noticeable improvements on matching quality with only a small increase in query time. Compared to earlier indexing techniques for real-time ER, our approach achieves significantly reduced indexing and query matching times while maintaining high matching accuracy

Customers' need for uniqueness theory versus brand congruence theory: the impact on satisfaction with social network sites

Social media brands may experience a lack of competitiveness and attraction due to the silent negative increase of customers' need for uniqueness (NFU). This is the result of a tension between the theory of brand congruence, that most brands endeavor to establish with their customers, and the theory of consumers' NFU, that many consumers aim to fulfill, that has not been previously examined. Whilst the theory of brand congruence states that consumers have a favorable attitude towards brands that greatly match their self-concept (brand similarity), the theory of uniqueness, when brand similarity is shared with others, generates avoidance of similarities with others, leading to a reduction in engagement and satisfaction. Social media platforms including Facebook are at risk from customers' NFU which significantly reduces users' satisfaction, hence reducing the attractiveness and usage of Facebook. To examine this, the paper identifies the paradox of similarity in relation to both theories and examines the relationship between consumers' socialization within Social Network Sites (SNSs), brand similarity, consumers' need for uniqueness, and consumers' satisfaction with the SNS. The conceptual model was tested using data from 341 consumers in the US. The findings show that whilst satisfaction with the SNS is enhanced by brand similarity and friend liking, it is undermined by customers' need for uniqueness. Implications for online brand communities and SNSs (Facebook) are discussed and guidance for future research is provided

Pengaruh Konsentrasi Chemical Oxygen Demand (Cod) Dan Ragi Terhadap Kinerja Granular Activated Carbon Dual Chamber Microbial Fuel Cells (Gac-dcmfcs)

Microbial fuel cell jika digunakan dalam pengolahan limbah, mampu menghasilkan energi yang bersih sebagai bagian dari pengolahan limbah yang efektif. Namun, beberapa hal yang sangat mempengaruhi kinerja MFC seperti komunitas mikroorganisme dan substrat belum ditemukan titik optimumnya. Penelitian ini menjawab tantangan tersebut dengan mengembangkan sebuah sistem MFC dengan menggunakan variasi konsentrasi COD dan ragi dalam mempengaruhi kinerja MFC. Limbah artifisial digunakan sebagai substrat MFCs karena diinginkan konsentrasi yang sesuai dengan tujuan penelitian. Media filter Granular activated carbon digunakan sebagai media perlekatan bakteri dalam pembentukan biofilm sehingga meningkatkan efisiensi penyisihan kontaminan. Variasi konsentrasi COD yang digunakan adalah 400, 800 dan 1200 mg/l dan konsentrasi ragi 1,5; 3 dan 4,5 g/l yang dioperasikan dalam kondisi batch selama proses seeding dan aklimatisasi dan kontinyu setelah proses aklimatisasi. Penyisihan COD tertinggi dihasilkan oleh reaktor 1200 mg/l dengan penambahan ragi 4,5 g/l yaitu sebesar 5624,6 mg/l atau sebesar 98,2%. Produksi listrik tertinggi dihasilkan pada konsentrasi 800 mg/l dan ragi 3 g/l dengan nilai 281,01 mW/m2. Dari perbandingan semua konsentrasi ragi dan COD, dapat disimpulkan bahwa pada range COD 800 – 1200 mg/l dan ragi 3 – 4,5 g/l microbial fuel cells menghasilkan penurunan COD dan produksi listrik yang optimum. Hasil menunjukkan bahwa metabolisme dan aktivitas mikroorganisme dalam biofilm sangat mempengaruhi kondisi operasional reaktor GACMFC

Pre- and Post-Fire Strength Assessment of Ferrocement beams

The results of an experimental investigation on the behavior of ferrocement beams after exposed to fire are presented in this paper. Different types of steel meshes are used compared with conventional reinforcement. The experimental program comprised casting and testing of eighteen beams having the dimensions of 100mm×100mm×1000mm. Three beams were reinforced as a conventional reinforcement. Each control beam was reinforced with two steel bars of diameter 8 mm in tension, two steel bar of diameter 6mm in compression and stirrups of 6 mm diameter placed at 200 mm intervals. The ferrocement beams were reinforced with steel meshes without any stirrups. Two types of steel meshes were used to reinforce the ferrocement laminate. These types are: square welded wire fabric, and expanded wire mesh. Single layer, double layers and three layers of square welded wire mesh were employed. Single layer and double layers of expanded wire mesh were employed. The experimental program was classified into three groups. First group was tested without exposure to fire, the second group was tested after exposure to fire for six hours and the last group was tested after exposure to fire under loading. All specimens were tested under 4-points flexural loadings. The performance of the test beams in terms of strength, stiffness, cracking behavior and energy absorption was investigated. The results showed that high serviceability and ultimate loads, crack resistance control, and better deformation characteristics could be achieved by using the proposed ferrocement forms

Parameter Genetik Sifat Pertumbuhan Dan Kerapatan Kayu Klon Eucalyptus Pellita F. Muell. Di Dua Tapak Yang Berbeda Di Kalimantan Timur

Industrial forest plantations have an important role in fulfilling the wood demand. Based on global industrial development, the forest plantations industry will increase in the following years. Eucalyptus pellita has become main species in Indonesia forest plantations because it has a short cycle and wood products are suitable to forest industry. The average productivity of E. pellita plantations in Indonesia is still low and high variation. In an effort to increase the productivity, the first step is a better understanding of genetic control on growth and basic density. This study aims to determine the genetic parameters for growth and basic density of E. pellita clones on two different sites. The clonal trials was conducted at two different sites. Both clonal trial are designed using RCBD. The number of clones tested in both trial was 30, 5 blocks and 25 tree/plot. The result of the study showed that the effects of clones vary greatly according the enviromental conditions. The clones- environemntal interaction of growth trait is higher than the basic density. This is in line with genetic parameters of growth trait that are less stable than the basic density. The expected genetic gain of growth trait is higher than the basic density and at the same time there was a weak genetic correlation (there is even a negative) between growth trait and basic density. Therefore carefulness is needed in selecting clones when the two traits are used as selection parameters

Geothermal based hybrid energy systems, toward eco-friendly energy approaches

Geothermal Energy is a very attractive source of naturally-occurring green renewable energy. Exploiting this natural resource is straightforward and causes almost no ill effects to the environment. But, while geothermal does not suffer the intermittence of other renewable sources, its extraction efficiency is fairly modest as compared to other sources. As a result, there has been significant interest recently in hybrid systems that integrate geothermal and other forms of energy to increase the output efficiency. This work will survey the different possible integrations involving geothermal energy. A review of the literature shows that the most common hybrid systems implementation involve the integration of geothermal with solar (45% of systems) followed by the integration of a cooling tower into the geothermal system (30% of systems). This work will also investigate the applications for geothermal hybrids and show that 44% of systems are designed for heating applications. Another 44% are used for cooling while only 12% are designed for electrical power generation. Complexity of control remains as the main obstacle facing hybrid multi-source energy systems including those involving geothermal energy

Adjuvant role of corticosteroids in the treatment of community-acquired pneumonia

AbstractBackgroundDespite progress in life-support measures and antimicrobial therapy, the mortality of severe pneumonia has not varied since the mid-1990s, suggesting that other factors are of crucial importance in the evolution of this respiratory infection.ObjectiveTo evaluate the impact of hydrocortisone infusion in community-acquired pneumonia (CAP) in the attenuation of systemic inflammation and reduction of sepsis-related complications.MethodsThe study enrolled 80 patients, clinically and radiolodically diagnosed as community-acquired pneumonia, admitted to Chest department, Respiratory Intensive Care Unit, General Medicine Department and General Medicine Intensive Care Unit of Zagazig University Hospitals. Sixty of them were randomized to receive hydrocortisone as a bolus dose of 200mg intravenously once (only at day 1) then 10mg/h IV infusion for 7days and twenty received placebo, along with antibiotics according to IDSA/ATS 2007 guidelines which were given for both groups. The following parameters were compared in both groups; PaO2 and PaO2/FiO2 ratio, length of hospital stay, duration of IV antibiotic treatment, duration of mechanical ventilation, weaning success from mechanical ventilation, pneumonia complication and hospital outcome.ResultsHydrocortisone treated patients showed a significant improvement in PaO2 and PaO2/FiO2 ratio, a significant reduction in White blood cell count, C-reactive protein levels, Erythrocyte sedimentation rate, a significant reduction in the duration of mechanical ventilation, duration of IV antibiotic treatment, pneumonia complications, and length of hospital stay. Also there was an improvement of hospital outcome, weaning success from mechanical ventilation and radiological resolution compared to the placebo group.ConclusionAdjunctive 7day course of low dose hydrocortisone IV in patients with CAP hastens clinical recovery and prevents the development of sepsis-related complications with a significant reduction in the duration of mechanical ventilation, duration of IV antibiotics and length of hospital stay with the improvement in hospital outcome and weaning success from mechanical ventilation