• Evaluating Critical Success Factors for Implementing Renewable Energy Strategies in the Dominican Republic

      Donastorg, Angelines; Renukappa, Suresh; Suresh, Subashini (Applied Science University, 2107-12)
      Global awareness and commitment, in regards to climate change, access to water and renewable energy deployment has risen in the last decade. However, many countries are still locked in unsustainable practices, specifically in regards to energy, this results in damaging consequences not just for the country but the world. Case in point of the Dominican Republic (DR), an island with an immense renewable energy potential, a growing economy and the financial aid of many international entities. Regardless of all this, “the business as usual” decision for the energy strategies is based on fossil foil. As a result, thousands of people are still without energy, the infrastructure itself is unreliable, and the cost of fossil fuel is 8% of the country’s GDP. In addition to, blackouts, the expensive tariff for users and unstable energy grid. Therefore, this paper discusses and critically evaluate critical success factors for implementing renewable energy strategies in the DR. For this purpose, an extensive literature review was done, along with interviews with the key actors in the renewable energy market of the DR. This resulted in the evaluation of the energy infrastructure by obtaining a clear view of the situation. Future work will involve creating a framework for implementation of renewables.
    • Bacterial Cell-Mineral Interface, Its Impacts on Biofilm Formation and Bioremediation

      Pouran, Hamid (Springer, 2019-03-29)
      This chapter aims to provide a better understanding of the bacterial cell attachment and biofilm formation on the mineral surfaces, which would result in improving our knowledge about: the interfacial forces governing the bacterial cell attachment, predicting trends of the biofilm formation and consequently biodegradation rates, and the contaminant’s fate in the diverse geological media (Pouran HM. Studying molecular and nanoscale interactions at metal oxide surfaces and their effects on bacterial adhesion, 2009). In both aqueous and terrestrial environments, bacterial cells tend to be attached to a surface and form biofilm. If they are associated to, e.g., a mineral surface, bacterial cells would remain in a more stable microenvironment instead of being removed by the water shear stress. Even the bacterial planktonic phase can be considered as a mechanism for translocation from one surface to the other rather than a prime lifestyle (Watnick and Kolter 2000; Young 2006). The biofilm formation, which completely covers the surface, initially begins by the adhesion of a small quantity of cells (Vadillo-rodri et al. 2006; Pouran et al. 2017). Among the different indigenous microbial species in the contaminated environments, some are capable of degrading pollutants and participating in the environmental remediation process. The bioremediation process of the contaminated soils and waters is often considered a promising low risk management tool. Even when the contamination poses an imminent threat and other approaches are essential, bioremediation often is a viable secondary strategy for the site maintenance (Haws et al. 2006; Pouran et al. 2017). Natural environments are dynamic and complex systems; therefore, characterization and identifying the underlying processes governing the contaminant’s fate are not easy. Examples of the natural environments heterogeneity are the diverse physicochemical properties of the soils and aquifers matrices (Stumm and Morgan 1996). As the soils and sediments are the prime surfaces for the bacterial cell attachment in most natural environments, elucidation of the surface properties of these constituents and their role in initiating cell adhesion and biofilm formation are of the key importance in understanding the bioremediation process. In fact, the cell-mineral interface reactions not only influence the biodegradation process but many natural phenomena are affected by them. Understanding role of physicochemical interactions at the bacterial cells and minerals interface in the cell adhesion (as well as biofilm formation, development, and behavior) is essential for planning effective bioremediation techniques. It could potentially help us to predict the contaminants’ fate, and trends of the biodegradation rates in different environments. Consequently, the improved knowledge of the cell-mineral interface enable us to design and apply more sophisticated bioremediation techniques as a viable approach towards tackling the soil and water environmental pollution problems. Figure 1 schematically represents an aquifer and biofilm formation on some of the most abundant minerals in the environment, iron and aluminum oxides. It also indicates some the major effects of cell-mineral interface interactions on different environmental processes (Stumm and Morgan 1996; Zachara and Fredrickson 2004; Cornell and Schwertmann 2003).
    • Characterizing the Cell Surface Properties of Hydrocarbon-Degrading Bacterial Strains, a Case Study

      Pouran, Hamid (Springer, 2019-03-29)
      This chapter describes some of the most common methods used to characterize the cell surface properties of the bacterial cells. As a case study, the focus of this chapter is on Sphingomonas spp., Sph2, which is a Gram negative and hydrophilic bacterial strain. The species used in this research was isolated from groundwater at a phenol-contaminated site. This hydrocarbon-degrading strain that can participate in bioremediation of polluted environments belongs to Sphingomonadaceae family. This group of bacteria is unique among Gram-negative cells because of having glycosphingolipids (GSL) instead of the lipopolysaccharide (LPS) layer in their cell wall. To characterize this strain, its surface properties were examined using potentiometric titration, modelling surface protonation sites using ProtoFit, zeta potential measurements, and attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. There is no published detailed study about cell wall characteristics of Sph2 yet, and this research reports such information for the first time. In addition, to investigate effects of the solution ionic strength on Sph2 adhesion behavior on metal oxides, its biofilm formation on hematite, as the model mineral, was evaluated in three different ionic strengths; ≈200 mM, 100 mM, and 20 mM. The ATR-FTIR analysis showed that despite the unique cell wall chemistry of Sph2 among the Gram-negative strains, its surface functional groups are similar to other bacterial species. Hydroxyl, carboxyl, phosphoryl, and amide groups were detected in Sph2 infrared spectra. The potentiometric titration results showed that Sph2 PZC is approximately 4.3. Optimizing the titration data based on ProtoFit non-electrostatic model (NEM) provided compatible results to the infrared spectroscopy analysis and four pKa values were identified; 3.9 ± 0.3, 5.9 ± 0.2, 8.9 ± 0.0, and 10.2 ± 0.1, which could be assigned to carboxyl, phosphate, amine, and hydroxyl groups, respectively. Zeta potential measurements demonstrated that changing the ionic strength from ≈200 mM to ≈20 mM shifts the zeta potential by ≈−20 mV. Direct observation showed that this alteration in the ionic strength coincides with a tenfold increase in the number of Sph2 attached cells to the hematite surface. This could be attributed to both electrostatic interactions between the cell and surface, and conformational changes of Sph2 surface biopolymers. In addition to reporting Sph2 cell wall characterization results for the first time, this study highlights importance of ionic strength in the cell adhesion to the mineral surfaces, which directly influence biofilm formation, bioremediation, and bacterial transport in aqueous systems.
    • Engineered Nanomaterials in the Environment, their Potential Fate and Behaviour and Emerging Techniques to Measure Them

      Pouran, Hamid (Springer, 2019-03-29)
      “There is plenty of room at the bottom” – this was title of Richard Feynman’s famous talk to the American Physical Society more than half a century ago. The Nobel Laureate, in his historic lecture, discussed the possibility of the direct manipulation of materials on the atomic and molecular level to unleash novel functions. Now, after decades of research, nanoscience faces a historic moment: moving from fundamental research towards a publically available technology, a turning point towards commercialization.
    • Atmin mediates kidney morphogenesis by modulating Wnt signaling

      Goggolidou, P.; Hadjirin, N.F.; Bak, A.; Papakrivopoulou, E.; Hilton, H.; Norris, D.P.; Dean, C.H. (Oxford University Press, 2018-10-15)
      The DNA damage protein and transcription factor Atmin (Asciz) is required for both lung tubulogenesis and ciliogenesis. Like the lungs, kidneys contain a tubular network that is critical for their function and in addition, renal ciliary dysfunction has been implicated in the pathogenesis of cystic kidney disease. Using the Atmin mouse mutant Gasping6 (Gpg6), we investigated kidney development and found it severely disrupted with reduced branching morphogenesis, resulting in fewer epithelial structures being formed. Unexpectedly, transcriptional levels of key cilia associated genes were not altered in Atmin(Gpg6/Gpg6) kidneys. Instead, Gpg6 homozygous kidneys exhibited altered cytoskeletal organization and modulation of Wnt signaling pathway molecules, including β-catenin and non-canonical Wnt/planar cell polarity (PCP) pathway factors, such as Daam2 and Vangl2. Wnt signaling is important for kidney development and perturbation of Wnt signaling pathways can result in cystic, and other, renal abnormalities. In common with other PCP pathway mutants, Atmin(Gpg6/Gpg6) mice displayed a shortened rostral-caudal axis and mis-oriented cell division. Moreover, intercrosses between Atmin(Gpg6/+) and Vangl2(Lp/+) mice revealed a genetic interaction between Atmin and Vangl2. Thus we show for the first time that Atmin is critical for normal kidney development and we present evidence that mechanistically, Atmin modifies Wnt signaling pathways, specifically placing it as a novel effector molecule in the non-canonical Wnt/PCP pathway. The identification of a novel modulator of Wnt signaling has important implications for understanding the pathobiology of renal disease.
    • A Case Study on the Microstructure of Fibrous Peat (West Lake, China)

      Wilkinson, Stephen; Zhao, Chaofa; Yang, Zhongxuam; Kun, Pan (Springer, 2018-09-21)
      The classification of peat soils generates a very large number of different types, from a descriptive perspective this is useful, however such a system generates too many options for engineering purposes. The behaviour of organic soils varies based on the quantity and type of organic material present within the soil. The effects of fibre content are particularly important. The West Lake in Hangzhou has been dredged many times during its history to allow it to maintain its beauty. During the most recent dredging the sludge from the lake was transported via a 4km pipeline and deposited inside the Jiangyangfan Reservoir. The organic soil situated in Jiangyangfan Ecopark is a particularly interesting peaty material. The organic sludge was mixed and homogenised during the transportation process, and then would have settled out within the reservoir. This resulted in a more than 20m thick peat layer deposited with an uneven surface. The Ecopark buildings were then constructed on top of this in 2008. A combined electron microscope and mechanical study of the microstructure and behaviour of the peat has been used to identify the engineering impact of the presence of relatively small numbers of fibres within the soil matrix. The fibres within the peat modify its behaviour such that it can no longer be understood within the typical critical state framework for soils. The peat starts to plastically deform from very small levels of applied stress, in addition it does not display a tension cut-off failure, and ultimately fails in shear.
    • The implementation of stakeholder management and building information modelling (BIM) in UK construction projects

      Singh, Sukhtaj; Chinyio, Ezekiel; Suresh, Subashini (Association of Researchers in Construction Management, 2018-09-03)
      The implementation and usage of Building Information Modelling (BIM) on construction projects affects procurement and the supply chain activities. BIM process is changing the traditional modus operandi of the construction industry where many projects have failed to achieve its objectives due to ineffective stakeholder management. An on-going PhD study explores how to mitigate delays and conflicts between stakeholders on BIM implemented projects in the UK. This paper is based on critical literature review and primary data collection through semi-structured interviews. Findings from the literature review show that BIM publication such as PAS 1192-2:2013, Employers Information Requirements (EIR) and BIM Execution Plan (BEP) sets out clear requirements for the coordination and collaboration process for the BIM model production. This provides a huge potential to enhance and facilitate communication among stakeholders. This helps in mitigating conflicts among stakeholders. The findings from the interviewees shows that BIM can help project teams to proactively satisfy stakeholders by engaging them early on in the construction process and seek solutions to avoid or minimise delays and conflicts. The paper concludes that it has culture, trust, people, technology, communication and structures are at its core for managing stakeholders within BIM projects.
    • Satellite-5G integration: a network perspective

      Giambene, Giovanni; Kota, Sastri; Pillai, Prashant (IEEE, 2018-09)
      Future 5G mobile communication systems are expected to integrate different radio access technologies, including the satellite component. Within the 5G framework, the terrestrial services can be augmented with the development of HTS systems and new mega-constellations meeting 5G requirements, such as high bandwidth, low latency, and increased coverage including rural areas, air, and seas. This article provides an overview of the current 5G initiatives and projects followed by a proposed architecture for 5G satellite networks where the SDN/NFV approach facilitates the integration with the 5G terrestrial system. In addition, a novel technique based on network coding is analyzed for the joint exploitation of multiple paths in such an integrated satellite-terrestrial system. For TCP-based applications, an analytical model is presented to achieve an optimal traffic split between terrestrial and satellite paths and optimal redundancy levels.
    • The Microbial Production of Polyhydroxyalkanoates from Waste Polystyrene Fragments Attained Using Oxidative Degradation

      Johnston, Brian; Radecka, Iza; Hill, David; Chiellini, Emo; Ilieva, Vassilka Ivanova (MDPI, 2018-08-29)
      Excessive levels of plastic waste in our oceans and landfills indicate that there is an abundance of potential carbon sources with huge economic value being neglected. These waste plastics, through biological fermentation, could offer alternatives to traditional petrol-based plastics. Polyhydroxyalkanoates (PHAs) are a group of plastics produced by some strains of bacteria that could be part of a new generation of polyester materials that are biodegradable, biocompatible, and, most importantly, non-toxic if discarded. This study introduces the use of prodegraded high impact and general polystyrene (PS0). Polystyrene is commonly used in disposable cutlery, CD cases, trays, and packaging. Despite these applications, some forms of polystyrene PS remain financially and environmentally expensive to send to landfills. The prodegraded PS0 waste plastics used were broken down at varied high temperatures while exposed to ozone. These variables produced PS flakes (PS1–3) and a powder (PS4) with individual acid numbers. Consequently, after fermentation, different PHAs and amounts of biomass were produced. The bacterial strain, Cupriavidus necator H16, was selected for this study due to its well-documented genetic profile, stability, robustness, and ability to produce PHAs at relatively low temperatures. The accumulation of PHAs varied from 39% for prodegraded PS0 in nitrogen rich media to 48% (w/w) of dry biomass with the treated PS. The polymers extracted from biomass were analyzed using nuclear magnetic resonance (NMR) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) to assess their molecular structure and properties. In conclusion, the PS0–3 specimens were shown to be the most promising carbon sources for PHA biosynthesis; with 3-hydroxybutyrate and up to 12 mol % of 3-hydroxyvalerate and 3-hydroxyhexanoate co-monomeric units generated.
    • α-Catenin Structure and Nanoscale Dynamics in Solution and in Complex with F-Actin

      Nicholl, Iain; Matsui, Tsutomu; Weiss, Thomas M; Stanley, Christopher B; Heller, William T; Martel, Anne; Farago, Bela; Callaway, David JE; Bu, Zimei (Elsevier, 2018-08-21)
      As a core component of the adherens junction, α-catenin stabilizes the cadherin/catenin complexes to the actin cytoskeleton for the mechanical coupling of cell-cell adhesion. α-catenin also modulates actin dynamics, cell polarity, and cell-migration functions that are independent of the adherens junction. We have determined the solution structures of the α-catenin monomer and dimer using in-line size-exclusion chromatography small-angle X-ray scattering, as well as the structure of α-catenin dimer in complex to F-actin filament using selective deuteration and contrast-matching small angle neutron scattering. We further present the first observation, to our knowledge, of the nanoscale dynamics of α-catenin by neutron spin-echo spectroscopy, which explicitly reveals the mobile regions of α-catenin that are crucial for binding to F-actin. In solution, the α-catenin monomer is more expanded than either protomer shown in the crystal structure dimer, with the vinculin-binding M fragment and the actin-binding domain being able to adopt different configurations. The α-catenin dimer in solution is also significantly more expanded than the dimer crystal structure, with fewer interdomain and intersubunit contacts than the crystal structure. When in complex to F-actin, the α-catenin dimer has an even more open and extended conformation than in solution, with the actin-binding domain further separated from the main body of the dimer. The α-catenin-assembled F-actin bundle develops into an ordered filament packing arrangement at increasing α-catenin/F-actin molar ratios. Together, the structural and dynamic studies reveal that α-catenin possesses dynamic molecular conformations that prime this protein to function as a mechanosensor protein.
    • Three-dimensional printing of PLA and PLA/PHA dumbbell-shaped specimens of crisscross and transverse patterns as promising materials in emerging application areas: Prediction study

      Gonzalez Ausejo, Jennifer; Rydz, Joanna; Musioł, Marta; Sikorska, Wanda; Janeczek, Henryk; Sobata, Michał; Włodarczyk, Jakub; Szeluga, Urszula; Hercog, Anna; Kowalczuk, Marek (Elsevier, 2018-08-18)
      This paper presents ex-ante examination of advanced polymer materials to detect defects and define and minimize the potential failure of novel polymer products before they arise. The effect of build directions on the properties of dumbbell-shaped specimens obtained by three-dimensional printing from polylactide and polylactide/polyhydroxyalkanoate commercial filaments was investigated, as well as the hydrolytic degradation of these specimens at 50 ºC and 70 ºC. Taking into account previous studies, we have found further dependences of the properties of 3D printed species before and during abiotic degradation from the orientation of printing. The initial assumption that only the contact time with the 3D printer platform leads to an increase in the crystalline phase during printing turned out to be insufficient. Further investigations of individual parts of the dumbbell-shaped specimens showed that the size of the specimens’ surface in contact with the platform also affected the structural ordering of the material.
    • Can Microsoft Academic help to assess the citation impact of academic books?

      Kousha, Kayvan; Thelwall, Mike (Elsevier, 2018-08-15)
      Despite recent evidence that Microsoft Academic is an extensive source of citation counts for journal articles, it is not known if the same is true for academic books. This paper fills this gap by comparing citations to 16,463 books from 2013 to 2016 in the Book Citation Index (BKCI) against automatically extracted citations from Microsoft Academic and Google Books in 17 fields. About 60% of the BKCI books had records in Microsoft Academic, varying by year and field. Citation counts from Microsoft Academic were 1.5 to 3.6 times higher than from BKCI in nine subject areas across all years for books indexed by both. Microsoft Academic found more citations than BKCI because it indexes more scholarly publications and combines citations to different editions and chapters. In contrast, BKCI only found more citations than Microsoft Academic for books in three fields from 2013-2014. Microsoft Academic also found more citations than Google Books in six fields for all years. Thus, Microsoft Academic may be a useful source for the impact assessment of books when comprehensive coverage is not essential.
    • Molecular Level Structure of Biodegradable Poly(Delta-Valerolactone) Obtained in the Presence of Boric Acid.

      Duale, Khadar; Zięba, Magdalena; Chaber, Paweł; Di Fouque, Dany Jeanne; Memboeuf, Antony; Peptu, Cristian; Radecka, Iza; Kowalczuk, Marek; Adamus, Grażyna (MDPI, 2018-08-14)
      In this study, low molecular weight poly(δ-valerolactone) (PVL) was synthesized through bulk-ring openings polymerization of δ-valerolactone with boric acid (B(OH)₃) as a catalyst and benzyl alcohol (BnOH) as an initiator. The resulting homopolymer was characterized with the aid of nuclear magnetic resonance (NMR) and mass spectrometry (MS) techniques to gain further understanding of its molecular structure. The electrospray ionization mass spectrometry (ESI-MS) spectra of poly(δ-valerolactone) showed the presence of two types of homopolyester chains-one terminated by benzyl ester and hydroxyl end groups and one with carboxyl and hydroxyl end groups. Additionally, a small amount of cyclic PVL oligomers was identified. To confirm the structure of PVL oligomers obtained, fragmentation of sodium adducts of individual polyester molecules terminated by various end groups was explored in ESI-MSn by using collision induced dissociation (CID) techniques. The ESI-MSn analyses were conducted both in positive- and negative ion mode. The comparison of the fragmentation spectra obtained with proposed respective theoretical fragmentation pathways allowed the structure of the obtained oligomers to be established at the molecular level. Additionally, using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), it was proven that regardless of the degree of oligomerization, the resulting PVL samples were a mixture of two types of linear PVL oligomers differing in end groups and containing just a small amount of cyclic oligomers that tended to be not visible at higher molar masses.
    • Physical Characteristics of Wireless Communication Channels for Secret Key Establishment: A Survey of the Research

      Bottarelli, Mirko; Epiphaniou, Gregory; Ismail, Dhouha Kbaier Ben; Karadimas, Petros; Al-Khateeb, Haider (Elsevier, 2018-08-14)
      Physical layer security protocols have recently been deployed in the context of Wireless communications. These are derived from the intrinsic characteristics of the communication media for key generation, sharing and randomness extraction. These protocols always seek to exhibit both low computational complexity and energy efficiency, whilst also maintain unconditionally secure communications. We present herein, a comprehensive literature review of existing “state-of-the-art” quantisation schemes for physical layer security, with a strong emphasis upon key performance metrics and intrinsic channel characteristics. Our survey seeks not only to concentrate upon the most common quantisation methods, hence their efficiency during key generation; but also crucially, describes the inherent trade-offs as between these standardised metrics. The exact way(s) in which these metrics are duly influenced by quantisation schemes is also discussed, by means of a comprehensive critical narrative of both existing and future developments in the field.
    • Comparison of experiment and theory for superelastic electron collision studies from laseraligned magnesium

      Pursehouse, James; Bostock, Chris; Nixon, Kate; Harvey, Matthew; Fursa, Dmitry V; Bray, Igor; Murray, Andrew James (APS, 2018-08-09)
      A combined experimental and theoretical study of superelastic electron collisions from laser-aligned magnesium atoms for a range of collision energies from 35eV to 55eV is presented. 24Mg atoms were excited from the 31S0 ground state to the 31P1 excited state using continuous-wave linearly-polarized laser radiation at ~285 nm. Electrons of well-defined energy Einc then de-excited the targets, and the superelastically scattered electrons emerging from the collision were detected as a function of scattering angle and laser polarization. Results for alignment of the target by the electron beam are presented for a range of scattering angles, for outgoing energies from Eout = 35eV to 55eV . The agreement between the measurements and the results of the convergent close-coupling theory are encouraging, but some discrepancies remain.
    • Gastric cooling and menthol cause an increase in cardiac parasympathetic efferent activity in healthy adult human volunteers.

      Kazadi, Lubobo-Claude; Fletcher, Janine; Barrow, Paul A (Wiley, 2018-08-02)
      What is the central question of this study? How do gastric stretch and gastric cooling stimuli affect cardiac autonomic control? What is the main finding and its importance? Gastric stretch causes an increase in cardiac sympathetic activity. Stretch combined with cold stimulation result in an elimination of the sympathetic response to stretch and an increase in cardiac parasympathetic activity, in turn resulting in a reduction in heart rate. Gastric cold stimulation causes a shift in sympathovagal balance towards parasympathetic dominance. The cold-induced bradycardia has the potential to decrease cardiac workload, which might be significant in individuals with cardiovascular pathologies. Gastric distension increases blood pressure and heart rate in young, healthy humans, but little is known about the effect of gastric stretch combined with cooling. We used a randomized crossover study to assess the cardiovascular responses to drinking 300 ml of ispaghula husk solution at either 6 or 37°C in nine healthy humans (age 24.08 ± 9.36 years) to establish the effect of gastric stretch with and without cooling. The effect of consuming peppermint oil capsules to activate cold thermoreceptors was also investigated. The ECG, respiratory movements and continuous blood pressure were recorded during a 5 min baseline period, followed by a 115 min post-drink period, during which 5 min epochs of data were recorded. Cardiac autonomic activity was assessed using time and frequency domain analyses of respiratory sinus arrhythmia to quantify parasympathetic autonomic activity, and corrected QT (QTc) interval analysis to quantify sympathetic autonomic activity. Gastric stretch only caused a significant reduction in QTc interval lasting up to 15 min, with a concomitant but non-significant increase in heart rate, indicating an increased sympathetic cardiac tone. The additional effect of gastric cold stimulation was significantly to reduce heart rate for up to 15 min, elevate indicators of cardiac parasympathetic tone and eliminate the reduction in QTc interval seen with gastric stretch only. Stimulation of gastric cold thermoreceptors with menthol also caused a significant reduction in heart rate and concomitant increase in the root mean square of successive differences. These findings indicate that gastric cold stimulation causes a shift in the sympathovagal balance of cardiac control towards a more parasympathetic dominant pattern.
    • Prophylactic antibiotic use in orthopaedic surgery - is it worth it?

      Patel, Bhavini; Morrissey, Hana; Rahman, Ayesha (EJBPS, 2018-08)
      Introduction: The administration of pre-operative prophylactic antibiotic is widely accepted in decreasing the risk of developing surgical site infections in orthopaedic surgery. The choice of antibiotic, duration, dosage and use of antibiotic laden bone cement varies substantially in clinical practise. Aims: This meta-analysis was conducted to assess the association of antibiotic choice, duration and dosage on the prevalence of surgical site infections in different types of orthopaedic surgery (hip replacements, knee arthroplasty, spinal surgery, ankle and foot surgery, shoulder surgery) and the identification of causative microorganisms. Methods: A literature search was performed in MEDLINE databases, Cochrane Controlled Trials Register published in the Cochrane Library, and Science Direct from January 2000-February 2018. Outcomes of interest included presence of post-operative surgical site infections. The Critical Appraisal Skills Programme tool was used to assess the risk of bias, extract outcomes of interest and to identify studies for inclusion in the meta-analysis. Results: The literature search revealed 169 studies out of which 18 studies were analysed and ultimately six studies in total were included in this meta-analysis. The pooled data investigating the post-operative deep surgical site infections rates favouring the use of prophylactic antibiotics (p=0.03). Only one study showed statistical significance (p=0.041) favouring the usage of high dosage antibiotic loaded bone cement in hemiarthroplasty procedures. Conclusion: This systematic review and meta-analysis recommends the use of high-dose antibiotic loaded bone cement and prophylactic oral antibiotics concurrently and as indicated, to prevent surgical site infections in hemiarthroplasties. The duration of prophylactic antibiotic use should be restricted to 24 hours commenced preoperatively or within 1-2 hours from incision. This systematic review also highlights the urgent need for more double blind RCT to validate the prophylactic use of antibiotics.
    • Branched Polyurethanes Based on Synthetic Polyhydroxybutyrate with Tunable Structure and Properties

      Brzeska, Joanna; Elert, Anna; Morawska, Magda; Sikorska, Wanda; Rutkowska, Maria; Kowalczuk, Marek (MDPI, 2018-07-28)
      Branched, aliphatic polyurethanes (PURs) were synthesized and compared to linear analogues. The influence of polycaprolactonetriol and synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) in soft segments on structure, thermal and sorptive properties of PURs was determined. Using FTIR and Raman spectroscopies it was found that increasing the R,S-PHB amount in the structure of branched PURs reduced a tendency of urethane groups to hydrogen bonding. Melting enthalpies (on DSC thermograms) of both soft and hard segments of linear PURs were higher than branched PURs, suggesting that linear PURs were more crystalline. Oil sorption by samples of linear and branched PURs, containing only polycaprolactone chains in soft segments, was higher than in the case of samples with R,S-PHB in their structure. Branched PUR without R,S-PHB absorbed the highest amount of oil. Introducing R,S-PHB into the PUR structure increased water sorption. Thus, by operating the number of branching and the amount of poly([R,S]-3-hydroxybutyrate) in soft segments thermal and sorptive properties of aliphatic PURs could be controlled.
    • Prediction studies of environment-friendly biodegradable polymeric packaging based on PLA. Influence of specimens’ thickness on the hydrolytic degradation profile

      Sikorska, W.; Musioł, M.; Rydz, J.; Zięba, M.; Rychter, P.; Lewicka, K.; Šiškova, A.; Mosnáčková, K.; Kowalczuk, Marek; Adamus, G. (Elsevier, 2018-07-11)
      Application of new biodegradable polymer packaging based on polylactide (PLA), susceptible to organic recycling, can help in the waste reduction in landfills. In this paper, the results of the study on abiotic degradation of PLA and its blend containing 15 mol% of poly[(R,S)-3-hydroxybutyrate], as a model for the first step of organic recycling were presented. The samples used for this study have different shapes and thicknesses: rigid films and cuboid-bars. Particular emphasis was placed on determining the pattern of degradation products released into the medium. Originally, the results of present study revealed that the application of electrospray ionization mass spectrometry supported by high performance liquid chromatography allowed envisaging the differences in the degradation products pattern released from the studied PLA-based samples differing in thickness. The significant differences in degradation products pattern were predominately observed in the first steps of incubation process and are caused by an autocatalytic effect, which occurs mainly during degradation of the large size PLA samples. Although, the thickness of PLA-based packaging changes the degradation product patterns, however this does not increase the total amounts of acids released to the medium. Thus, it may be concluded that thickness should not affect significantly organic recycling of the packaging.