Search results for: reverse transcriptase

Authors: Mouna Baassi, Mohamed Moussaoui, Sanchaita Rajkhowa, Hatim Soufi, Said Belaaouad

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The objective of this paper is to address the challenging task of targeting Human Immunodeficiency Virus type 1 Reverse Transcriptase (HIV-1 RT) in the treatment of AIDS. Reverse Transcriptase inhibitors (RTIs) have limitations due to the development of Reverse Transcriptase mutations that lead to treatment resistance. In this study, a combination of statistical analysis and bioinformatics tools was adopted to develop a mathematical model that relates the structure of compounds to their inhibitory activities against HIV-1 Reverse Transcriptase. Our approach was based on a series of compounds recognized for their HIV-1 RT enzymatic inhibitory activities. These compounds were designed via software, with their descriptors computed using multiple tools. The most statistically promising model was chosen, and its domain of application was ascertained. Furthermore, compounds exhibiting comparable biological activity to existing drugs were identified as potential inhibitors of HIV-1 RT. The compounds underwent evaluation based on their chemical absorption, distribution, metabolism, excretion, toxicity properties, and adherence to Lipinski's rule. Molecular docking techniques were employed to examine the interaction between the Reverse Transcriptase (Wild Type and Mutant Type) and the ligands, including a known drug available in the market. Molecular dynamics simulations were also conducted to assess the stability of the RT-ligand complexes. Our results reveal some of the new compounds as promising candidates for effectively inhibiting HIV-1 Reverse Transcriptase, matching the potency of the established drug. This necessitates further experimental validation. This study, beyond its immediate results, provides a methodological foundation for future endeavors aiming to discover and design new inhibitors targeting HIV-1 Reverse Transcriptase.

Keywords: QSAR, ADMET properties, molecular docking, molecular dynamics simulation, reverse transcriptase inhibitors, HIV type 1

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Authors: T. E. Tshikalange, B. C. Mophuting

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Traditional medicine often consists of complex ingredients prepared from a mixture of plant species. These herbal mixtures are used in the treatment of various ailments such as sexually transmitted diseases including HIV. The present study was carried out to determine the biological activities of the herbal mixture used traditionally in the treatment of sexually transmitted diseases. This herbal mixture consists of four plant species from families Asteraceae, Bignoniaceae, Fabaceae, and Myrtaceae. Five crude extracts (hexane, dichloromethane, methanol, water and boiled) of the herbal mixture were investigated for anti-gonococcal, anti-inflammatory, and reverse transcriptase activities. The anti-inflammatory activity of the plant extracts was determined by measuring the extract inhibitory effect on the pro-inflammatory enzyme lipoxygenase. The extracts were also tested for anti-HIV activity against recombinant HIV-1 enzyme using non-radioactive HIV-RT colorimetric assay. The boiled extract exhibited good anti-inflammatory activity with an IC₅₀ of 87 µg/ml compared to that of the positive control quercetin (IC₅₀= 92 µg/ml). All the other extracts showed little or no activity. Hexane extract was the only extract that showed reverse transcriptase extract inhibitory effect with an IC₅₀ of 74 µg/ml. Anti-gonococcal and cytotoxicity investigations are underway. The preliminary results support the use of herbal mixture by traditional healers.

Keywords: sexually transmitted diseases, lipoxygenase, anti-inflammatory, herbal mixture

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Authors: Daria Zabolotnaya, Svetlana Degtyareva, Veronika Kanestri, Danila Konnov

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An adequate choice of the initial antiretroviral treatment determines the treatment efficacy. In the clinical guidelines in Russia non-nucleoside reverse transcriptase inhibitors (NNRTIs) are still considered to be an option for first-line treatment while pretreatment drug resistance (PDR) testing is not routinely performed. We conducted a cohort retrospective study in HIV-positive treatment naïve patients of the H-clinic (Moscow, Russia) who performed PDR testing from July 2017 to November 2021. All the information was obtained from the medical records anonymously. We analyzed the mutations in reverse transcriptase and protease genes. RT-sequences were obtained by AmpliSens HIV-Resist-Seq kit. Drug resistance was defined using the HIVdb Program v. 8.9-1. PDR was estimated using the Stanford algorithm. Descriptive statistics were performed in Excel (Microsoft Office, 2019). A total of 261 HIV-1 infected patients were enrolled in the study including 197 (75.5%) male and 64 (24.5%) female. The mean age was 34.6±8.3 years. The median CD4 count – 521 cells/µl (IQR 367-687 cells/µl). Data on risk factors of HIV-infection were scarce. The total quantity of strains containing mutations in the reverse transcriptase gene was 75 (28.7%). From these 5 (1.9%) mutations were associated with PDR to nucleoside reverse transcriptase inhibitors (NRTIs) and 30 (11.5%) – with PDR to NNRTIs. The number of strains with mutations in protease gene was 43 (16.5%), from these only 3 (1.1%) mutations were associated with resistance to protease inhibitors. For NNRTIs the most prevalent PDR mutations were E138A, V106I. Most of the HIV variants exhibited a single PDR mutation, 2 were found in 3 samples. Most of HIV variants with PDR mutation displayed a single drug class resistance mutation. 2/37 (5.4%) strains had both NRTIs and NNRTIs mutations. There were no strains identified with PDR mutations to all three drug classes. Though earlier data demonstrated a lower level of PDR in HIV treatment naïve population in Russia and our cohort can be not fully representative as it is taken from the private clinic, it reflects the trend of increasing PDR especially to NNRTIs. Therefore, we consider either pretreatment testing or giving the priority to other drugs as first-line treatment necessary.

Keywords: HIV, resistance, mutations, treatment

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Authors: Nasser R. El-Brollosy, Roberta Loddo

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6-Benzyl-1-(ethoxymethyl)-5-isopropyluracil (Emivirine) and its corresponding 1-benzyloxymethyl analogue (TNK-651) showed high activity against HIV-1. The present study describes synthesis of novel emivirine analogues by reaction of chloromethyl ethyl ether with uracils having 5-ethyl / isopropyl and 6-(3,5-dimethoxybenzyl) substituents. A series of new TNK-651 analogues substituted at N-1 with phenoxyethoxymethyl moiety was prepared on treatment of the corresponding uracils with bis(phenoxyethoxy) methane. The newly synthesized non-nucleosides were tested for biological activity against wild type HIV-1 IIIB as well as the resistant strains N119 (Y181C), A17 (K103N + Y181C), and the triple mutant EFVR (K103R + V179D + P225H) in MT-4 cells. Some of the tested compounds showed good activities. Among them 6-(3,5-dimethylbenzyl)-5-ethyl-1-[2-(phenoxyethyl) oxymethyl]uracil which showed inhibitory potency higher than emivirine against both wild type HIV-1 and the tested mutant strains.

Keywords: Emivirine, HIV, non-nucleoside reverse transcriptase, uracils

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Authors: Tomasz Frączek, Agata Paneth, Rafał Kamiński, Agnieszka Krakowiak, Piotr Paneth

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Azoles are a promising class of the new generation of HIV-1 nonnucleoside reverse transcriptase inhibitors (NNRTIs). From thousands of reported compounds, many possess the same basic structure of an aryl substituted azole ring linked by a thioglycolamide chain with another aromatic ring. To find novel extensions for this primary scaffold, we explored the 5-position substitution of triazole NNRTIs using molecular docking followed by synthesis of selected compounds. We discovered that heterocyclic substituents in 5-position of the triazole ring are detrimental to the inhibitory activity of compounds with 4-membered thioglycolamide linker. This substitution seems to be viable only for compounds with a shorter 2-membered linker such as in derivatives of 4‐benzyl‐3‐(benzyl-sulfanyl)‐5‐(thiophen‐2‐yl)‐4H‐1,2,4‐triazole reported earlier. A new scaffold of 2‐[(4‐benzyl‐5‐methyl‐4H‐1,2,4‐triazol‐3‐yl)sulfanyl]‐N‐phenylacetamide has been identified in this study.

Keywords: docking, molecular modeling, drug design, novel scaffolds

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Authors: Ergun Kaya

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Apple mosaic virus (ApMV) is an ilarvirus causing harmful damages and product loses in many plant species. Because of xylem and phloem vessels absence, plant meristem tissues used for meristem cultures are virus-free, but sometimes only meristem cultures are not sufficient for virus elimination. Cryotherapy, a new method based on cryogenic techniques, is used for virus elimination. In this technique, 0.1-0.3mm meristems are excised from organized shoot apex of a selected in vitro donor plant and these meristems are frozen in liquid nitrogen (-196 °C) using suitable cryogenic technique. The aim of this work was to develop an efficient procedure for ApMV-free hazelnut via cryotherapy technique and confirmation of virus-free plants using Reverse Transcriptase-PCR technique. 100% virus free plantlets were obtained using droplet-vitrification method involved cold hardening in vitro cultures of hazelnut, 24 hours sucrose preculture of meristems on MS medium supplemented with 0.4M sucrose, and a 90 min PVS2 treatment in droplets.

Keywords: droplet vitrification, hazelnut, liquid nitrogen, PVS2

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Authors: Gowtham Kalkere Jayanna, Mohamad Nazri Husin

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Graph theory, chemistry, and technology are all combined in cheminformatics. The structure and physiochemical properties of organic substances are linked using some useful graph invariants and the corresponding molecular graph. In this paper, we study specific reverse topological indices such as the reverse sum-connectivity index, the reverse Zagreb index, the reverse arithmetic-geometric, and the geometric-arithmetic, the reverse Sombor, the reverse Nirmala indices for the bistar graphs B (n: m) and the corona product Kₘ∘Kₙ', where Kₙ' Represent the complement of a complete graph Kₙ.

Keywords: reverse topological indices, bistar graph, the corona product, graph

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Authors: Agnieszka Krzemińska, Katarzyna Świderek, Vicente Molinier, Piotr Paneth

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In order to understand in details the interactions between ligands and the enzyme isotope effects were studied between clinically used drugs that bind in the active site of Human Immunodeficiency Virus Reverse Transcriptase, HIV-1 RT, as well as triazole-based inhibitor that binds in the allosteric pocket of this enzyme. The magnitudes and origins of the resulting binding isotope effects were analyzed. Subsequently, binding isotope effect of the same triazole-based inhibitor bound in the active site were analyzed and compared. Together, these results show differences in binding origins in two sites of the enzyme and allow to analyze binding mode and place of newly synthesized inhibitors. Typical protocol is described below on the example of triazole ligand in the allosteric pocket. Triazole was docked into allosteric cavity of HIV-1 RT with Glide using extra-precision mode as implemented in Schroedinger software. The structure of HIV-1 RT was obtained from Protein Data Bank as structure of PDB ID 2RKI. The pKa for titratable amino acids was calculated using PROPKA software, and in order to neutralize the system 15 Cl- were added using tLEaP package implemented in AMBERTools ver.1.5. Also N-terminals and C-terminals were build using tLEaP. The system was placed in 144x160x144Å3 orthorhombic box of water molecules using NAMD program. Missing parameters for triazole were obtained at the AM1 level using Antechamber software implemented in AMBERTools. The energy minimizations were carried out by means of a conjugate gradient algorithm using NAMD. Then system was heated from 0 to 300 K with temperature increment 0.001 K. Subsequently 2 ns Langevin−Verlet (NVT) MM MD simulation with AMBER force field implemented in NAMD was carried out. Periodic Boundary Conditions and cut-offs for the nonbonding interactions, range radius from 14.5 to 16 Å, are used. After 2 ns relaxation 200 ps of QM/MM MD at 300 K were simulated. The triazole was treated quantum mechanically at the AM1 level, protein was described using AMBER and water molecules were described using TIP3P, as implemented in fDynamo library. Molecules 20 Å apart from the triazole were kept frozen, with cut-offs established on range radius from 14.5 to 16 Å. In order to describe interactions between triazole and RT free energy of binding using Free Energy Perturbation method was done. The change in frequencies from ligand in solution to ligand bounded in enzyme was used to calculate binding isotope effects.

Keywords: binding isotope effects, molecular dynamics, HIV, reverse transcriptase

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Authors: Sabine A. Zauchner-Studnicka

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As the term indicates, reverse-mentoring flips the classical roles of mentoring: In school, students take over the role of mentors for adults, i.e. teachers or parents. Originally reverse-mentoring stems from US enterprises, which implemented this innovative method in order to benefit from the resources of skilled younger employees for the enhancement of IT competences of senior colleagues. However, reverse-mentoring in schools worldwide is rare. Based on empirical studies and theoretical approaches, in this article an implementation model for reverse-mentoring is developed in order to bring the significant potential reverse-mentoring has for education into practice.

Keywords: reverse-mentoring, innovation in education, implementation model, school education

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Authors: Hailu Getnet

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This study focus on reverse innovation on performance outcomes across developed and subsistence markets context. The subsistence market consists two third of the world population and the largest international market. To date, it has been neglected because of its issues of perceived challenges and seeming unattractiveness compared to the established markets in the west. However, subsistence markets are becoming source of reverse innovation; an innovation that is likely to be adopted first in developing world and successfully traded globally. In response, there is a growing interest on reverse innovation to power the future. Based on the theories of innovation and growing subsistence market literatures, the study propose drivers and outcomes of reverse innovation, a potential similarities and difference in benefiting and challenging firms and consumers in subsistence and developed markets.

Keywords: reverse innovation, subsistence market, developing world, developed market

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Authors: C. Baidada, M. H. Abidi, A. Jakimi, E. H. El Kinani

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Reverse engineering has become a viable method to measure an existing system and reconstruct the necessary model from tis original. The reverse engineering of behavioral models consists in extracting high-level models that help understand the behavior of existing software systems. In this paper, we propose an approach for the reverse engineering of sequence diagrams from the analysis of execution traces produced dynamically by an object-oriented application using petri nets. Our methods show that this approach can produce state diagrams in reasonable time and suggest that these diagrams are helpful in understanding the behavior of the underlying application. Finally we will discuss approachs and tools that are needed in the process of reverse engineering UML behavior. This work is a substantial step towards providing high-quality methodology for effectiveand efficient reverse engineering of sequence diagram.

Keywords: reverse engineering, UML behavior, sequence diagram, execution traces, petri nets

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Authors: F. Lhafiane, A. Elbyed, M. Bouchoum

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Reverse Logistics (RL) Process is considered as complex and dynamic network that involves many stakeholders such as: suppliers, manufactures, warehouse, retails, and costumers, this complexity is inherent in such process due to lack of perfect knowledge or conflicting information. Ontologies, on the other hand, can be considered as an approach to overcome the problem of sharing knowledge and communication among the various reverse logistics partners. In this paper, we propose a semantic representation based on hybrid architecture for building the Ontologies in an ascendant way, this method facilitates the semantic reconciliation between the heterogeneous information systems (ICT) that support reverse logistics Processes and product data.

Keywords: Reverse Logistics, information management, heterogeneity, ontologies, semantic web

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Authors: Vallejo Michael, Acuña Edgar, Roa Juan David, Peñuela Rosa, Parra Alejandra, Casallas Daniela, Rodriguez Sheyla

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Congenital Zika Virus Syndrome is an entity composed by a variety of birth defects presented in newborns that have been exposed to the Zika Virus during pregnancy. The syndrome characteristic features are severe microcephaly, cerebral tissue abnormalities, ophthalmological abnormalities such as uveitis and chorioretinitis, arthrogryposis, clubfoot deformity and muscular tone abnormalities. The confirmatory test is the Reverse transcription polymerase chain reaction (RT-PCR) associated to the physical findings. Here we present the case of a newborn with microcephaly whose mother presented a confirmed Zika Virus infection during the third trimester of pregnancy, despite of the evident findings and the history of Zika infection the RT-PCR in amniotic and cerebrospinal fluid of the newborn was negative. RT-PCR has demonstrated a low sensibility in samples with low viral loads, reason why, we propose a clinical diagnosis in patients with clinical history of Zika Virus infection during pregnancy accompanied by evident clinical manifestations of the child.

Keywords: congenital, Zika virus, microcephaly, reverse transcriptase polymerase chain reaction

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Authors: Adèle Oliva, Samuel Fosso Wamba

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This study looks at how firms can create competitive advantages through effective reserve logistics strategies. Upon using data collected from reverse supply chain managers of electronic commerce companies, the study found that improved reverse logistics management can have a positive impact on companies’ business benefits. These include playing a role in the implementation of many factors that highly influence the decision to purchase, customers’ loyalty, as well as increasing companies’ turnover. As a result, through an efficient design and management of their reverse flow, companies can decrease the costs associated to returned products.

Keywords: reverse logistics, competitive advantage, case study, business value

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Authors: Veenu Bala, Yashpal S. Chhonker, Bhavana Kushwaha, Rabi S. Bhatta, Gopal Gupta, Vishnu L. Sharma

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According to UNAIDS 2013 estimate nearly 52% of all individuals living with HIV are now women of reproductive age (15–44 years). Seventy-five percent cases of HIV acquisition are through heterosexual contacts and sexually transmitted infections (STIs), attributable to unsafe sexual behaviour. Each year, an estimated 500 million people acquire atleast one of four STIs: chlamydia, gonorrhoea, syphilis and trichomoniasis. Trichomonas vaginalis (TV) is exclusively sexually transmitted in adults, accounting for 30% of STI cases and associated with pelvic inflammatory disease (PID), vaginitis and pregnancy complications in women. TV infection resulted in impaired vaginal milieu, eventually favoring HIV transmission. In the absence of an effective prophylactic HIV vaccine, prevention of new infections has become a priority. It was thought worthwhile to integrate HIV prevention and reproductive health services including unintended pregnancy protection for women as both are related with unprotected sex. Initially, nonoxynol-9 (N-9) had been proposed as a spermicidal agent with microbicidal activity but on the contrary it increased HIV susceptibility due to surfactant action. Thus, to accomplish an urgent need of novel woman controlled non-detergent microbicidal spermicides benzenepropanamine analogues have been synthesized. At first, five benzenepropanamine-dithiocarbamate hybrids have been synthesized and evaluated for their spermicidal, anti-Trichomonas and anti-fungal activities along with safety profiling to cervicovaginal cells. In order to further enhance the scope of above study benzenepropanamine was hybridized with thiourea as to introduce anti-HIV potential. The synthesized hybrid molecules were evaluated for their reverse transcriptase (RT) inhibition, spermicidal, anti-Trichomonas and antimicrobial activities as well as their safety against vaginal flora and cervical cells. simulated vaginal fluid (SVF) stability and pharmacokinetics of most potent compound versus N-9 was examined in female Newzealand (NZ) rabbits to observe its absorption into systemic circulation and subsequent exposure in blood plasma through vaginal wall. The study resulted in the most promising compound N-butyl-4-(3-oxo-3-phenylpropyl) piperazin-1-carbothioamide (29) exhibiting better activity profile than N-9 as it showed RT inhibition (72.30 %), anti-Trichomonas (MIC, 46.72 µM against MTZ susceptible and MIC, 187.68 µM against resistant strain), spermicidal (MEC, 0.01%) and antifungal activity (MIC, 3.12–50 µg/mL) against four fungal strains. The high safety against vaginal epithelium (HeLa cells) and compatibility with vaginal flora (lactobacillus), SVF stability and least vaginal absorption supported its suitability for topical vaginal application. Docking study was performed to gain an insight into the binding mode and interactions of the most promising compound, N-butyl-4-(3-oxo-3-phenylpropyl) piperazin-1-carbothioamide (29) with HIV-1 Reverse Transcriptase. The docking study has revealed that compound (29) interacted with HIV-1 RT similar to standard drug Nevirapine. It may be concluded that hybridization of benzenepropanamine and thiourea moiety resulted into novel lead with multiple activities including RT inhibition. A further lead optimization may result into effective vaginal microbicides having spermicidal, anti-Trichomonas, antifungal and anti-HIV potential altogether with enhanced safety to cervico-vaginal cells in comparison to Nonoxynol-9.

Keywords: microbicidal, nonoxynol-9, reverse transcriptase, spermicide

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Authors: F. Lhafiane, A. Elbyed, M. Bouchoum

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The design of Reverse logistics Network has attracted growing attention with the stringent pressures from both environmental awareness and business sustainability. Reverse logistical activities include return, remanufacture, disassemble and dispose of products can be quite complex to manage. In addition, demand can be difficult to predict, and decision making is one of the challenges tasks. This complexity has amplified the need to develop an integrated architecture for product return as an enterprise system. The main purpose of this paper is to design Multi agent system (MAS) architecture using the Prometheus methodology to efficiently manage reverse logistics processes. The proposed MAS architecture includes five types of agents: Gate keeping Agent, Collection Agent, Sorting Agent, Processing Agent and Disposal Agent which act respectively during the five steps of reverse logistics Network.

Keywords: reverse logistics, multi agent system, prometheus methodology

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Authors: Neha Asthana, Vishal Krishna Prasad

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Reverse logistics and green supply chain form an interconnected and interwoven network of parameters that contribute to enhancement and incremental exchange in the triple bottom line in the consistently changing and fragmenting markets of the globalizing markets of today. Reverse logistics not only contributes to completing the supply chain in a comprehensive and synchronized manner but also contributes to a significant degree in optimizing green supply chains through procedures such as recycling, refurbishing etc. contributing to waste reduction. Carbon trading, owing to its limitations in the global context and being in a nascent stage seeks plethora of research to determine its full application in synergy with reverse logistics and green supply chain.

Keywords: reverse logistics, carbon trading, carbon emissions, green supply chain

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Authors: Ail Akbar Emamverdian, Neriman Özada, Atabak Rahimzadeh Ilkhchi, Zahra Emamverdian

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The reverse shoulder prosthesis is an innovative procedure design to treat of (GH) joint problems with severe rotator cuff deficiency. The original reverse shoulder prosthesis was invented by France surgery in1985 and has been in clinical use in the United States in 2004. These prostheses consist of baseplate that attached to the glenoid, in order to hold a spherical component, and humeral part consist of polyethylene insert which is flat. This prosthesis is the ‘reverse’ configuration. The indications for the reverse prosthesis are: (1) treating failed hemi arthroplasty with irrecoverable rotator cuff tears, (2) relief of painful arthritis associated with cuff tear arthropathy, (3) instauration after tumor resection, (4) pseudo paralysis because of irrecoverable rotator cuff tears (5) some fractures of the shoulder which reverse shoulder prostheses is only the option for treatment. This prosthesis resulting in relief of pain and decreasing the range of motion in above indications. However, this prosthesis and its applications such as notching of the scapula, dislocation of the prosthesis parts and acromial stress fractures. In this article the reverse shoulder prostheses, indication has been reviewed. This study can make clear aspect of reverse shoulder prosthesis that can help to find some solution in future.

Keywords: prostheses, complications, reverse shoulder prosthesis, indications

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Authors: Mohd Hazwan bin Yusof, Hiroshi Katanoda

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In order to clarify the structure of the cold flow discharged from the vortex tube (VT), the pressure of the cold flow was measured, and a simple flow visualization technique using a 0.75 mm-diameter needle and an oily paint is made to study the reverse flow at the cold exit. It is clear that a negative pressure and positive pressure region exist at a certain pressure and cold fraction area, and that a reverse flow is observed in the negative pressure region.

Keywords: flow visualization, pressure measurement, reverse flow, vortex tube

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Authors: Max Filipe Goncalves, Alessandra Concilio, Rodrigo Shimada

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The waste frying oil is highly pollutant when disposed incorrectly in the environment. Is necessary search of the Reverse Logistics to identify how can be structure to return the waste like this to productive chain and to be used in the new process. In this context, the objective of this paper is to analyze the perspective of the waste frying oil in São Paulo, and its dimensions in the production of biodiesel. Subjacent factors such as the agents, motivators and legal aspects were analyzed to demonstrate it. Then, the SWOT matrix was built with the aspects observed and the forces, weaknesses, opportunities and threats of the reverse logistic chain in São Paulo.

Keywords: biodiesel, perspective, reverse logistic, WFO

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Authors: S. Dhib, S. A. Addouche, T. Loukil, A. Elmhamedi

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In this paper, a reverse supply chain network is investigated for a decision making. This decision is surrounded by complex flows of returned products, due to the increasing quantity, the type of returned products and the variety of recovery option products (reuse, recycling, and refurbishment). The most important problem in the reverse logistic network (RLN) is to orient returned products to the suitable type of recovery option. However, returned products orientations from collect sources to the recovery disposition have not well considered in performance model. In this study, we propose a performance model for designing a network configuration on reverse logistics. Conceptual and analytical models are developed with taking into account operational, economic and environmental factors on designing network.

Keywords: reverse logistics, network design, performance model, open loop configuration

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Authors: Mokali Veeresham

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In this work, the high-entropy alloy TaNbHfZrTi was processed at room temperature by each step novel reverse rolling up to a 90% reduction in thickness. The reverse rolled 90% samples subsequently used for annealing at 800°C and 1000°C temperatures for 1h to understand phase stability, microstructure, texture, and mechanical properties. The reverse rolled 90% condition contains BCC single-phase; upon annealing at 800°C temperature, the formation of secondary phase BCC-2 prevailed. The partial recrystallization and complete recrystallization microstructures were developed for annealed at 800°C and 1000°C temperatures, respectively. The reverse rolled condition, and 1000°C annealed temperature exhibit extraordinary room temperature tensile properties with high tensile strength (UTS) 1430MPa and 1556 MPa without compromising loss of ductility consists of an appreciable amount of 21% and 20% elongation, respectively.

Keywords: refractory high entropy alloys, reverse rolling, recrystallization, microstructure, tensile properties

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Authors: Rajesh A. Rane, Shital S. Naphade, Rajshekhar Karpoormath

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Thiozolidin-4-one, a mimic of thiazolobenzimidazole (TBZ) has drawn many attentions due to its potent and selective inhibition against the HIV-1 and low toxicity by binding to the allosteric site of the reverse transcriptase (RT) as a non-nucleoside RT inhibitor (NNRTI). Similarly, marine bromopyrrole alkaloids are well known for their diverse array of anti-infective properties. Hence, we have reported synthesis and in vitro HIV-1 RT inhibitory activity of a series of 4-thiazolidinone-bromopyrrole alkaloid hybrids tethered with amide linker. The results of in vitro HIV-1 RT kit assay showed that some of the compounds, such as 4c, 4d, and 4i could effectively inhibit RT activity. Among them, compounds 4c having 4-chlorophenyl substituted 4-thiazolidione ring was the best one with the IC50 value of 0.26 µM. The sturdy emerges with key structure-activity relationship that pyrrole-NH-free core benefited inhibition against HIV-1 RT inhibition. This study identified conjugate 4c with potent activity and selectivity as promising compound for further drug development to HIV.

Keywords: antiviral drugs, bromopyrrole alkaloids, HIV-1 RT inhibition, 4-thiazolidinone

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Authors: Aloke Bapli, Debabrata Seth

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Graphene oxide (GO) is the two-dimensional (2D) nanoscale allotrope of carbon having several physiochemical properties such as high mechanical strength, high surface area, strong thermal and electrical conductivity makes it an important candidate in various modern applications such as drug delivery, supercapacitors, sensors etc. GO has been used in the photothermal treatment of cancers and Alzheimer’s disease etc. The main idea to choose GO in our work is that it is a surface active molecule, it has a large number of hydrophilic functional groups such as carboxylic acid, hydroxyl, epoxide on its surface and in basal plane. So it can easily interact with organic fluorophores through hydrogen bonding or any other kind of interaction and easily modulate the photophysics of the probe molecules. We have used different spectroscopic techniques for our work. The Ground-state absorption spectra and steady-state fluorescence emission spectra were measured by using UV-Vis spectrophotometer from Shimadzu (model-UV-2550) and spectrofluorometer from Horiba Jobin Yvon (model-Fluoromax 4P) respectively. All the fluorescence lifetime and anisotropy decays were collected by using time-correlated single photon counting (TCSPC) setup from Edinburgh instrument (model: LifeSpec-II, U.K.). Herein, we described the photophysics of a hydrophilic molecule 7-(n,n׀-diethylamino) coumarin-3-carboxylic acid (7-DCCA) in the reverse micelles containing GO. It was observed that photophysics of dye is modulated in the presence of GO compared to photophysics of dye in the absence of GO inside the reverse micelles. Here we have reported the solvent relaxation and rotational relaxation time in GO containing reverse micelle and compare our work with normal reverse micelle system by using 7-DCCA molecule. Normal reverse micelle means reverse micelle in the absence of GO. The absorption maxima of 7-DCCA were blue shifted and emission maxima were red shifted in GO containing reverse micelle compared to normal reverse micelle. The rotational relaxation time in GO containing reverse micelle is always faster compare to normal reverse micelle. Solvent relaxation time, at lower w₀ values, is always slower in GO containing reverse micelle compare to normal reverse micelle and at higher w₀ solvent relaxation time of GO containing reverse micelle becomes almost equal to normal reverse micelle. Here emission maximum of 7-DCCA exhibit bathochromic shift in GO containing reverse micelles compared to that in normal reverse micelles because in presence of GO the polarity of the system increases, as polarity increases the emission maxima was red shifted an average decay time of GO containing reverse micelle is less than that of the normal reverse micelle. In GO containing reverse micelle quantum yield, decay time, rotational relaxation time, solvent relaxation time at λₑₓ=375 nm is always higher than λₑₓ=405 nm, shows the excitation wavelength dependent photophysics of 7-DCCA in GO containing reverse micelles.

Keywords: photophysics, reverse micelle, rotational relaxation, solvent relaxation

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Authors: Nirmal Kundu, Chandan Bhar, Visveswaran Pandurangan

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Technology is the most valued possession for a country or an organization. The economic development depends not on stock of technology but on the capabilities how the technology is being exploited. The technology transfer is the best way how the developing countries have an access to state-of- the-art technology. Traditional technology transfer is a unidirectional phenomenon where technology is transferred from developed to developing countries. But now there is a change of wind. There is a general agreement that global shift of economic power is under way from west to east. As China and India are making the transition from users to producers, and producers to innovators, this has increasing important implications on economy, technology and policy of global trade. As a result, Reverse technology transfer has become a phenomenon and field of study in technology management. The term “Reverse Technology Transfer” is not well defined. Initially the concept of Reverse technology transfer was associated with the phenomenon of “Brain drain” from developing to developed countries. In the second phase, Reverse Technology Transfer was associated with the transfer of knowledge and technology from subsidiaries to multinationals. Finally, time has come now to extend the concept of reverse technology transfer to two different organizations or countries related or unrelated by traditional technology transfer but the transfer or has essentially received the technology through traditional mode of technology transfer. The objective of this paper is to study; 1) the present status of Reverse technology transfer, 2) the factors which are the enablers and barriers of Reverse technology transfer and 3) how the reverse technology transfer strategy can be integrated in the technology policy of a country which will give the countries an economic boost. The research methodology used in this study is a combination of literature review, case studies and key informant interviews. The literature review includes both published as well as unpublished sources of literature. In case study, attempt has been made to study the records of reverse technology transfer that have been occurred in developing countries. In case of key informant interviews, informal telephonic discussions have been carried out with the key executives of the organizations (industry, university and research institutions) who are actively engaged in the process of technology transfer- traditional as well as reverse. Reverse technology transfer is possible only by creating technological capabilities. Following four important enablers coupled with government active and aggressive action can help to build technology base to reach to the goal of Reverse technology transfer 1) Imitation to innovation, 2) Reverse engineering, 3) Collaborative R & D approach, and 4) Preventing reverse brain drain. The barriers that come in the way are the mindset of over dependence, over subordination and parent–child attitude (not adult attitude). Exploitation of these enablers and overcoming the barriers of reverse technology transfer, the developing countries like India and China can prove that going “reverse” is the best way to move forward and again establish themselves as leader of the future world.

Keywords: barriers of reverse technology transfer, enablers of reverse technology transfer, knowledge transfer, reverse technology transfer, technology transfer

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Authors: Jaegu Choi, Jae-Mean Koo, Chang-Sung Seok, Byungwoo Moon

Abstract:

Since massive earthquakes in the world have been reported recently, the safety of nuclear power plants for seismic loading has become a significant issue. Seismic loading is the reverse cyclic loading, consisting of repeated tensile and compression by longitudinal and transverse wave. Up to this time, the study on characteristics of fracture toughness under reverse cyclic loading has been unsatisfactory. Therefore, it is necessary to obtain the fracture toughness under reverse cyclic load for the integrity estimation of nuclear power plants under seismic load. Fracture resistance (J-R) curves, which are used for determination of fracture toughness or integrity estimation in terms of elastic-plastic fracture mechanics, can be derived by the fracture resistance test using single specimen technique. The objective of this paper is to study the effects of reverse cyclic loading on a fracture resistance curve of ESG specimen, having a similar stress gradient compared to the crack surface of the real pipe. For this, we carried out the fracture toughness test under the reverse cyclic loading, while changing incremental plastic displacement. Test results showed that the J-R curves were decreased with a decrease of the incremental plastic displacement.

Keywords: reverse cyclic loading, j-r curve, ESG specimen, incremental plastic displacement

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Authors: Magno Enrique Mendoza Meza

Abstract:

This paper deals with the comparison of three control techniques: the hysteresis on-off control (HyOOC), the hybrid on-off control (HOOC) and the simple Structured Treatment Interruptions (sSTI). These techniques are applied to the mathematical model developed by Kirschner and Webb. To compare these techniques we use a cost functional that minimize the wild-type virus population and the mutant virus population, but the main objective is to minimize the systemic cost of treatment and maximize levels of healthy CD4+ T cells. HyOOC, HOOC, and sSTI are applied to the drug therapies using a reverse transcriptase and protease inhibitors; simulations show that these controls maintain the uninfected cells in a small, bounded neighborhood of a pre-specified level. The controller HyOOC and HOOC are designed by appropriate choice of virtual equilibrium points.

Keywords: virus dynamics, on-off control, hysteresis, multi-drug therapies

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Authors: Devender Mandala, Paul Watts

Abstract:

Cis-Nucleosides mainly lamivudine (3TC) and emtricitabine (FTC) are an important tool in the treatment of Human immune deficiency virus (HIV), Hepatitis B virus (HBV) and Human T-Lymotropoic virus (HTLV). Lamivudine and emtricitabine are potent nucleoside analog reverse transcriptase inhibitors (nRTI). These two drugs are synthesized by a four-stage process from the starting materials: menthyl glyoxylate hydrate and 1,4-dithane-2,5-diol to produce the 5-hydroxy oxathiolane which upon acetylation with acetic anhydride to yield 5-acetoxy oxathiolane. Then glycosylation of this acetyl product with silyl protected nucleoside to produce the intermediate. The reduction of this intermediates can provide the final targets. Although there are several different methods reported for the synthesis of lamivudine and emtricitabine as a single enantiomer, we required an efficient route, which was suitable for large-scale synthesis to support the development of these compounds. In this process, we successfully prepared the intermediates of lamivudine and emtricitabine without using any solvents and catalyst, thus promoting the green synthesis. All the synthesized compound were confirmed by TLC, GC, Mass, NMR and 13C NMR spectroscopy.

Keywords: emtricitabine, green synthesis, lamivudine, nucleoside

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Authors: Faisal Mehmood

Abstract:

In this globalization era, the supply chain management has acquired strategic importance in diverse business environments. In the current highly competitive business environment, the success of any business considerably depends on the efficiency of the supply chain. Management has now realized that due to the inefficiency of any member of supply chain, the profitability of the business will be affected. This paper proposes an analysis of backward supply chain in the beverages industry of Pakistan. Although reuse of products and materials is a common phenomenon, companies have long ignored this important part of the supply chain, known as backward supply chain or reverse logistics. The beverage industry is among the pioneers of backward supply chain or reverse logistics in Pakistan. The empty glass bottles are returned back from the point of consumption to the warehouse for refilling and reusability purposes. Due to the lack of information on reverse flow of logistics and more attention on the forward distribution, beverages industry in Pakistan is facing high rate of inefficiencies and ineffectiveness. Analysis of backward or reverse logistics practiced in beverages industry is the subject of this study in which framework dictating the current needs of market will be developed.

Keywords: backward supply chain, reverse logistics, refilling, re-usability

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Authors: M. Sarai Atab, A. Smallbone, A. P. Roskilly

Abstract:

A thermodynamic study is performed on the Reverse Osmosis (RO) desalination process for brackish water. The detailed RO model of thermodynamics properties with and without an energy recovery device was built in Simulink/MATLAB and validated against reported measurement data. The efficiency of desalination plants can be estimated by both the first and second laws of thermodynamics. While the first law focuses on the quantity of energy, the second law analysis (i.e. exergy analysis) introduces quality. This paper used the Main Outfall Drain in Iraq as a case study to conduct energy and exergy analysis of RO process. The result shows that it is feasible to use energy recovery method for reverse osmosis with salinity less than 15000 ppm as the exergy efficiency increases twice. Moreover, this analysis shows that the highest exergy destruction occurs in the rejected water and lowest occurs in the permeate flow rate accounting 37% for 4.3% respectively.

Keywords: brackish water, exergy, irrigation, reverse osmosis (RO)

Procedia PDF Downloads 133