Reversibility in Chemical Reactions

open access bookIn this chapter we give an overview of techniques for the modelling and reasoning about reversibility of systems, including outof- causal-order reversibility, as it appears in chemical reactions. We consider the autoprotolysis of water reaction, and model it with the Calculus of Covalent Bonding, the Bonding Calculus, and Reversing Petri Nets. This exercise demonstrates that the formalisms, developed for expressing advanced forms of reversibility, are able to model autoprotolysis of water very accurately. Characteristics and expressiveness of the three formalisms are discussed and illustrated

Local reversibility in a Calculus of Covalent Bonding

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.We introduce a process calculus with a new prefixing operator that allows us to model locally controlled reversibility. Actions can be undone spontaneously, as in other reversible process calculi, or as pairs of concerted actions, where performing a weak action forces undoing of another action. The new operator in its full generality allows us to model out-of-causal order computation, where causes are undone before their effects are undone, which goes beyond what typical reversible calculi can express. However, the core calculus, which uses only the reduced form of the new operator, is well behaved as it satisfied causal consistency. We demonstrate the usefulness of the calculus by modelling the hydration of formaldehyde in water into methanediol, an industrially important reaction, where the creation and breaking of some bonds are examples of locally controlled out-of-causal order computation

Reversible Computation: Extending Horizons of Computing

This open access State-of-the-Art Survey presents the main recent scientific outcomes in the area of reversible computation, focusing on those that have emerged during COST Action IC1405 "Reversible Computation - Extending Horizons of Computing", a European research network that operated from May 2015 to April 2019. Reversible computation is a new paradigm that extends the traditional forwards-only mode of computation with the ability to execute in reverse, so that computation can run backwards as easily and naturally as forwards. It aims to deliver novel computing devices and software, and to enhance existing systems by equipping them with reversibility. There are many potential applications of reversible computation, including languages and software tools for reliable and recovery-oriented distributed systems and revolutionary reversible logic gates and circuits, but they can only be realized and have lasting effect if conceptual and firm theoretical foundations are established first

Reversible Computation: Extending Horizons of Computing

This open access State-of-the-Art Survey presents the main recent scientific outcomes in the area of reversible computation, focusing on those that have emerged during COST Action IC1405 "Reversible Computation - Extending Horizons of Computing", a European research network that operated from May 2015 to April 2019. Reversible computation is a new paradigm that extends the traditional forwards-only mode of computation with the ability to execute in reverse, so that computation can run backwards as easily and naturally as forwards. It aims to deliver novel computing devices and software, and to enhance existing systems by equipping them with reversibility. There are many potential applications of reversible computation, including languages and software tools for reliable and recovery-oriented distributed systems and revolutionary reversible logic gates and circuits, but they can only be realized and have lasting effect if conceptual and firm theoretical foundations are established first

Management of bone defects with Bio-oss

Introduction: The defects in the alveolar bone might appear as a result of congenital malformations, traumatic injuries, periodontal disease, surgical traumas, chronic periapical changes and tumors from benign or malignant origin. The aim of this study was to provide solid and healthy area with application of Bio-Oss in the defect. Materials and methods: Based on the clinical diagnosisestablished by previously taken history, clinical examination and radiographic images oral-surgery interventions was made. To realize the aim of this work, augmentative material was implicated in the bone defects made in the patients after removal of follicular cyst, chronic periapical lesion, and parodontopathia. During the first and seventh day of the interventions, the patients have been followed through from aspect of possible development of local and general complications after the oral-surgery intervention. After period of one, three and six mount control x-ray was made. Results: Obtained results confirmed that: volume of the socket and defect of the bone was kept, fast revascularization was achieved, bone formation and slow resorption of the augmentative material was achieved, and period of normal healing without infection was also achieved. Conclusions: The augmentative materials used for treatment of bone defects besides their basic chemical and physical characteristics referring to their solubility in the body fluids, the transformation, modulation and resorption must be completely safe or secure, i.e. not to bring any risk of infection, immunological risk, physiological intolerance or inhibition of the process of restitutio ad integrum. In our study Bio-Oss was confirmed as augmentative material who had this characteristics. Keywords: bone defect, resorption of the bone, augmentative material, Bio-Os

Laser Photonic Energy Delivery in Clinical Dentistry: Scrutiny of Parameter Variables.

Laser use in the disciplines of clinical dentistry, oral surgery and oral medicine have developed during a period of over 30 years. During that time, from a rudimentary base of non-awareness of the scientific processes involved or scope of possible application, the knowledge and understanding of lasers has grown and benefitted from structured research, postgraduate courses and qualifications. Both the sophistication and scope of use of laser photonic energy has increased significantly, to the extent that lasers can be incorporated to benefit almost all areas of patient-centred clinical dentistry. Research into laser-assisted therapies has reinforced the importance of “light dose” in order to maximise the benefits of applied coherent, monochromatic light energy to a given procedure, while minimising the risk of conversion of excessive energy into collateral thermal damage. This thesis by concurrent publication provides a thorough examination of both ablative surgical laser-tissue interaction and sub-ablative photobiomodulation. The importance of achieving accurate light-dose levels of irradiation of oral hard and soft tissues remains fundamental to delivery of appropriate laser therapy whilst minimising the risk of collateral damage to adjacent, non-target oral hard and soft tissues. As demonstrated through published systematic reviews, it is significant to note the absence of full operating parametry in many peer-reviewed published studies; such omission compromises the opportunity to achieve accurate laser applications that are chosen as adjunctive to a clinical procedure. In addition, the consequence of poorly or inaccurately calibrated optic fibre photonic delivery, as the method of choice with visible and near infra-red wavelength “diode” lasers, may compromise the intended outcome of a clinical procedure; taken as a component of a poorly designed study, such errors may distort the development of laser-assisted therapy through inaccurate data acquisition and interpretation arising out of calibration errors. Once receiving peer-reviewed publication, any reference incorporating laser use helps define the expansion of knowledge and use for the clinician; there is a consequent responsibility to ensure that published studies that directly affect clinical application of laser use are fully detailed, to avoid subsequent misinterpretation and maltreatment. A further area of concern remains the persistence in attribution of post-surgical healing phenomena, by way of photobiomodulation to those laser wavelengths solely within the “optical window” range of 650 – 1350 nanometers. Both clinical and underlying biochemical data support the concept of “uneventful healing” with all laser wavelengths in dentistry, and exploration of key biochemical processes provide testimony to both photo- and possible thermo-biomodulation actions that follow laser irradiation. Through examination of the many potential errors that may affect post-irradiation outcome, it is concluded that the risk would appear of greater significance with lower, photobiomodulation (PBM) fluences. The small difference between benefit and non-benefit with PBM, either as a stand-alone therapy or adjunctive to a surgical laser procedure, defines a perspective that underlines the balance of this thesis

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Reactivity of platinum (II) complexes with (O,S) bidentate ligands towards DNA model systems for cancer treatment

The FDA-approved platinum(II) drugs cisplatin, carboplatin, and oxaliplatin, are the mainstays of present chemotherapy regimens. Nevertheless, there are a variety of severe side effects, including nephrotoxicity, neurotoxicity, ototoxicity, and nausea as well as the problems of drug resistance and dosage limitations. In addition, the current platinum(II) drugs are all administered intravenously, where they can interact with blood components, including human serum albumin (HSA), the most abundant protein in the human bloodstream, that inhibits the action of platinum(II) drugs. In the cytoplasm, the activated drug species bind to cytoplasmic sulfur-containing nucleophiles such as glutathione (GSH), metallothionein, methionine, and other cysteine-rich proteins before the DNA binding. Consequently, these nucleophilic species act as scavengers, decreasing the availability of reactive species and contributing to drug resistance. Therefore, using non-leaving groups that contain soft donor atoms might reduce the affinity of the platinum(II) complexes toward biomolecular sulfur donors. In this work, we present a design of platinum(II) complexes based on antisymbiosis (trans effect), and HSAB principles, with the aim of reducing the affinity of the synthesized platinum(II) complexes towards sulfur-containing nucleophiles, thus reducing the side effects as well as overcoming the drug inhibition and resistance drawbacks