Computing with Noise - Phase Transitions in Boolean Formulas

Computing circuits composed of noisy logical gates and their ability to represent arbitrary Boolean functions with a given level of error are investigated within a statistical mechanics setting. Bounds on their performance, derived in the information theory literature for specific gates, are straightforwardly retrieved, generalized and identified as the corresponding typical-case phase transitions. This framework paves the way for obtaining new results on error-rates, function-depth and sensitivity, and their dependence on the gate-type and noise model used.Comment: 10 pages, 2 figure

Seawater Desalination: A Review of Forward Osmosis Technique, Its Challenges, and Future Prospects

Currently over 845 million people are believed to be living under severe water scarcity, and an estimated 2.8 billion people across the globe are projected to come under serious water scarcity by the year 2025, according to a United Nations (UN) report. Seawater desalination has gained more traction as the solution with the most potential for increasing global freshwater supplies amongst other solutions. However, the economic and energy costs associated with the major desalination technologies are considered intrinsically prohibitive largely due to their humongous energy requirements alongside the requirements of complex equipment and their maintenance in most cases. Whilst forward osmosis (FO) is being touted as a potentially more energy efficient and cost-effective alternative desalination technique, its efficiency is challenged by draw solutes and the draw solutes recovery step in FO applications alongside other challenges. This paper looks at the present situation of global water scarcity, and a brief leap into the major desalination technologies employed. A closer look at the key drivers of FO as a seawater desalination technique in their individual domain and its outlook as an technology are further highlighted

Characterization of the upper respiratory tract microbiomes of patients with pandemic H1N1 influenza.

The upper respiratory tract microbiome has an important role in respiratory health. Influenza A is a common viral infection that challenges that health, and a well-recognized sequela is bacterial pneumonia. Given this connection, we sought to characterize the upper respiratory tract microbiota of individuals suffering from the pandemic H1N1 influenza A outbreak of 2009 and determine if microbiome profiles could be correlated with patient characteristics. We determined the microbial profiles of 65 samples from H1N1 patients by cpn60 universal target amplification and sequencing. Profiles were examined at the phylum and nearest neighbor species levels using the characteristics of patient gender, age, originating health authority, sample type and designation (STAT/non-STAT). At the phylum level, Actinobacteria-, Firmicutes- and Proteobacteria-dominated microbiomes were observed, with none of the patient characteristics showing significant profile composition differences. At the nearest neighbor species level, the upper respiratory tract microbiomes were composed of 13-20 species and showed a trend towards increasing diversity with patient age. Interestingly, at an individual level, most patients had one to three organisms dominant in their microbiota. A limited number of discrete microbiome profiles were observed, shared among influenza patients regardless of patient status variables. To assess the validity of analyses derived from sequence read abundance, several bacterial species were quantified by quantitative PCR and compared to the abundance of cpn60 sequence read counts obtained in the study. A strong positive correlation between read abundance and absolute bacterial quantification was observed. This study represents the first examination of the upper respiratory tract microbiome using a target other than the 16S rRNA gene and to our knowledge, the first thorough examination of this microbiome during a viral infection

The grand canonical ABC model: a reflection asymmetric mean field Potts model

We investigate the phase diagram of a three-component system of particles on a one-dimensional filled lattice, or equivalently of a one-dimensional three-state Potts model, with reflection asymmetric mean field interactions. The three types of particles are designated as $A$, $B$, and $C$. The system is described by a grand canonical ensemble with temperature $T$ and chemical potentials $T\lambda_A$, $T\lambda_B$, and $T\lambda_C$. We find that for $\lambda_A=\lambda_B=\lambda_C$ the system undergoes a phase transition from a uniform density to a continuum of phases at a critical temperature $\hat T_c=(2\pi/\sqrt3)^{-1}$. For other values of the chemical potentials the system has a unique equilibrium state. As is the case for the canonical ensemble for this $ABC$ model, the grand canonical ensemble is the stationary measure satisfying detailed balance for a natural dynamics. We note that $\hat T_c=3T_c$, where $T_c$ is the critical temperature for a similar transition in the canonical ensemble at fixed equal densities $r_A=r_B=r_C=1/3$.Comment: 24 pages, 3 figure

The Role of Sulfated Materials for Biodiesel Production from Cheap Raw Materials

There is an urgent need to reduce global greenhouse gas emissions, yet to date the decarbonization of the transportation industry has been slow and of particular difficulty. While fossil fuel replacements such as biodiesel may aid the transition to a less polluting society, production at the industrial scales required is currently heavily dependent on chemical catalysis. Conventional two-step homogenous routes require the challenging separation of catalyst from the obtained product; however, heterogenous solid catalysts bring new considerations such as material stability, surface area, porosity, deactivation effects, and reduced reactivities under mild conditions. Nanomaterials present an attractive solution, offering the high reactivity of homogenous catalysts without complex recyclability issues. Slightly less reactive, acidic sulfated nanomaterials may also demonstrate greater stability to feedstock impurity, extending lifetime and improved versatility to a range of starting feeds. There remains, however, much work to be done in demonstrating the full-scale feasibility of such catalysts. This review explores recent developments over time in acidic sulfated nanocatalysis for biodiesel production, with particular focus on metal oxides, magnetic nanoparticles, silica-supported nanomaterials, and acidic carbon nanocatalysts. Included are various summaries of current progress in the literature, as well as recommendations for future research

Novel draw solution for forward osmosis based solar desalination

Forward osmosis (FO) is an emerging technology for water desalination which requires no external force for its operation. The performance of FO for water desalination is dependent on draw solution (DS) that must provide high osmosis pressure, minimum reverse flux and efficient separation of water. This work proposes an innovative concept of energy efficient material as DS having two functions, i.e. high osmotic pressure and efficient absorption of solar energy for the regeneration phase. The potassium functionalised carbon nanofibers (K/CNF) which are highly solar absorptive, are engineered and suspended in triethylene glycol (TEG) aqueous solution with different concentrations to act as a novel DS. The TEG-K/CNF is fully characterised for morphological appearance and thermophysical characteristics before using in FO experiments. It is found that the osmotic pressure and water flux of the novel DS are directly dependent on the concentration of K/CNF and TEG. The draw solution is re-concentrated by evaporating the water aided by the highly solar absorptive K/CNF under simulated solar flux. The vapours are condensed and the quality of product water is found to be comparable with potable water standard. The novel concept proposed in this study has the potential to be used in arid areas where solar energy is abundant to fulfil the potable water needs

Effect of the loading of di- and tri-valent metal cations on the performance of sulfated silica-titania nano-catalyst in the esterification reaction

In this study, a series of sulfated silica-titania catalysts were modified by metal cations (Al, Co, Zr, Cr, and Zn) to enhance the catalytic activity and stability of sulfated silica-titania in the esterification reaction. The results indicated that the sulfate phases of sulfated silica-titania were mostly changed to TiO(SO4) by the incorporation of support cations. It affected the acidity content of the samples and the bonding strength between the sulfate group and the support surface. Moreover, the mean pore size was drastically increased which had a positive influence on the activity of the sample in the esterification reaction. The results of catalytic activity showed that all the samples had suitable activity at 120°C, whereas the sulfated silica-titania catalyst that was reinforced by Al3+ exhibited less activity reduction by setting the temperature to 90°C. The highest conversion of oleic acid (90.7 ± 2%) was obtained under optimal reaction conditions including the temperature of 90°C, methanol/oleic acid molar ratio of 9:1, 3 wt.% catalyst, and reaction time of 3 h. The sulfated silica-titania modified by Al3+ also exhibited good catalytic stability for six cycles while a high reduction in the activity of sulfated silica-titania catalyst was observed

Introducing the JMBE themed issue on science communication

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