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Introduction: non-surgical periodontal treatment, primarily comprising scaling and root planing, is crucial for the maintenance and enhancement of oral health. However, the invasive nature of this procedure often leads to patient discomfort and pain, which may deter individuals from seeking necessary dental care, ultimately compromising their oral health outcomes. Methods: This prospective randomized crossover split-mouth study involved the application of Ultra-Low Frequency (ULF) Transcutaneous Electrical Nerve Stimulation (TENS) in 20 adult patients undergoing non-surgical periodontal treatment. Pain and discomfort levels were quantitatively assessed during procedures conducted with and without the ULF-TENS intervention. Results: The assessment of maximum voluntary opening, pain intensity, and overall comfort levels indicated a statistically significant reduction in pain (p < 0.0001) and discomfort (p < 0.0001) when ULF-TENS was employed during the treatment, and an increase in the maximum mouth opening after TENS (p = 0.00062). Conclusions: The findings of this pilot study suggest that ULF-TENS may serve as a valuable adjunctive therapy in non-surgical periodontal treatment by reducing pain and discomfort, potentially enhancing patient comfort and compliance. Further research with larger sample sizes is warranted to confirm these findings.

Abstract Experiments have been carried out to analyse the characteristics of liquid suspensions which exhibit a non-uniform solid concentration. In order to investigate the bed behaviour, a new probe was developed and tested to measure the instantaneous concentration of solid particles. Attention is focused on slugging solid-liquid fluidized beds, where regions of low solid concentration alternate with regions of high solid concentration. The analysis of the results allowed some relevant flow characteristics (slug frequencies and slug velocities) to be recognized.

Three identical upflow laboratory-scale biofilters, inoculated with the benzene-degrading strain Pseudomonas sp. NCIMB 9688 but filled up with different packing media (PM), specifically raw sugarcane bagasse, sieved sugarcane bagasse and peat, were employed to eliminate benzene from waste air. Biofilters performances were evaluated by continuous runs in parallel at different influent benzene concentrations, sequentially stepped up through three different superficial gas velocities (31, 61, and 122 m h(-1)). The peat-packed biofilter exhibited the best performances over the whole experimentation, ensuring removal efficiency of 100% for influent benzene concentrations < or = 0.05 g m(-3), regardless of the superficial gas velocity, and up to 0.4 g m(-3) at 31 m h(-1). Maximum elimination capacities of biofilters packed with raw and sieved sugarcane bagasse and with peat were 3.2, 6.4 and 26 g mPM(-3) h(-1) at 6.1, 12 and 31 g mPM(-3) h(-1) loading rates, resulting in 52, 53 and 84% removals, respectively. The bacterial concentration distribution along the medium was shown to depend on the benzene loading rate and a correlation between specific benzene elimination rate and biomass concentration was established for biofilters packed with sieved sugarcane bagasse and peat. The macrokinetics of the process were also studied using the profiles of benzene and biomass concentrations, collected under different conditions over the height of both biofilters, and a zeroth-order kinetic model was shown to describe successfully the degradation process.

Experimental results of a one‐fifth scale cold laboratory model of a circulating fluidized‐bed pilot plant for biomass gasification are reported here. Measurements revealed that the solid circulation rate is a function of the superficial gas velocity in the riser and the total mass load in the system. A novel dimensionless scaling parameter introduced describes the dimensionless mass turnover. Experiments were carried out varying both particle diameter, 170 μm ≤ d ≤ 860 μm, and density, 1,480 kg/m3 ≤ ρs ≤ 8,900 kg/m3. An excellent prediction for the mass turnover was obtained for mass loads varying from 1 to 15 kg and throughout the whole particle size and density range using the equations derived. Furthermore, the particle‐size distribution is a scaling parameter to be matched between a model and an industrial plant.

Biofilm detachment in liquid fluidized bed biological reactors was investigated to point out how different mechanisms influence the process. Erosion due to liquid shear and abrasion due to collisions of particles were considered as possible mechanisms of biomass detachment in liquid fluidized beds. A dimensional analysis technique allowed the identification of the significant parameters affecting the process. The influence of these parameters was established on a lab-scale reactor. An empirical model was proposed to correlate the experimental data and to analyze the effect of some characteristic quantities, such as particle Reynolds number, biomass fraction, liquid shear stress and solid concentration, on the detachment rate. Detachment rate strongly increased with fluid velocity while, owing to modifications in biofilm structure and morphology during the biological growth, it slightly decreased with liquid shear stress.

We report on a new class of hybrid electronic devices based on a DNA nucleoside (deoxyguanosine lipophilic derivative) whose assembled polymeric ribbons interconnect a submicron metallic gate. The device exhibits large conductivity at room temperature, rectifying behaviour and strong current-voltage hysteresis. The transport mechanism through the molecules is investigated by comparing films with different self-assembling morphology. We found that the main transport mechanism is connected to pi-pi interactions between guanosine molecules in adjacent ribbons, consistently with the results of our first-principles calculations.

We present a first-principle investigation of quadruple helix nanowires, consisting of stacked planar hydrogen-bonded guanine tetramers. Our results show that long wires form and are stable in potassium-rich conditions. We present their electronic bandstructure and discuss the interpretation in terms of effective wide-bandgap semiconductors. The microscopic structural and electronic properties of the guanine quadruple helices make them suitable candidates for molecular nanoelectronics.

Several assemblies of guanine molecules are investigated by means of first-principle calculations. Such structures include stacked and hydrogen-bonded dimers, as well as vertical columns and planar ribbons, respectively, obtained by periodically replicating the dimers. Our results are in good agreement with experimental data for isolated molecules, isolated dimers, and periodic ribbons. For stacked dimers and columns, the stability is affected by the relative charge distribution of the pi orbitals in adjacent guanine molecules. pi-pi coupling in some stacked columns induces dispersive energy bands, while no dispersion is identified in the planar ribbons along the connections of hydrogen bonds. The implications for different materials comprised of guanine aggregates are discussed. The bandstructure of dispersive configurations may justify a contribution of band transport (Bloch type) in the conduction mechanism of deoxyguanosine fibres, while in DNA-like configurations band transport should be negligible.

We present a first principle study about the stability and the electronic properties of a new biomolecular solid-state material, obtained by the self-assembling of guanine (G) molecules. We consider hydrogen-bonded planar ribbons in isolated and stacked configurations. These aggregates present electronic properties similar to inorganic wide-bandgap semiconductors. The formation of Bloch-type orbitals is observed along the stacking direction, while it is negligible in the ribbon plane. Global band-like conduction may be affected by a dipole-field which spontaneously arises along the ribbon axis. Our results indicate that G-ribbon assemblies are promising materials for biomolecular nanodevices, consistently with recent experimental results.