This study presents the removal of phosphate from aqueous solution using a new silver nanoparticles-loaded tea activated carbon (AgNPs-TAC) material. In order to reduce costs, the tea activated ...carbon was produced from tea residue. Batch adsorption experiments were conducted to evaluate the effects of impregnation ratio of AgNPs and TAC, pH solution, contact time, initial phosphate concentration and dose of AgNPs-AC on removing phosphate from aqueous solution. Results show that the best conditions for phosphate adsorption occurred at the impregnation ratio AgNPs/TAC of 3% w/w, pH 3, and contact time lasting 150 min. The maximum adsorption capacity of phosphate on AgNPs-TAC determined by the Langmuir model was 13.62 mg/g at an initial phosphate concentration of 30 mg/L. The adsorption isotherm of phosphate on AgNPs-TAC fits well with both the Langmuir and Sips models. The adsorption kinetics data were also described well by the pseudo-first-order and pseudo-second-order models with high correlation coefficients of 0.978 and 0.966, respectively. The adsorption process was controlled by chemisorption through complexes and ligand exchange mechanisms. This study suggests that AgNPs-TAC is a promising, low cost adsorbent for phosphate removal from aqueous solution.
Supervised feature selection is an important problem in pattern recognition. Of the many methods introduced, those based on the mutual information and conditional mutual information measures are ...among the most widely adopted approaches. In this paper, we re-analyze an interesting paper on this topic recently published by Sotoca and Pla (Pattern Recognition, Vol. 43 Issue 6, June, 2010, pp. 2068–2081). In that work, a method for supervised feature selection based on clustering the features into groups is proposed, using a conditional mutual information based distance measure. The clustering procedure minimizes the objective function named the minimal relevant redundancy—mRR criterion. It is proposed that this objective function is the upper bound of the information loss when the full set of features is replaced by a smaller subset. We have found that their proof for this proposition is based on certain erroneous assumptions, and that the proposition itself is not true in general. In order to remedy the reported work, we characterize the specific conditions under which the assumptions used in the proof, and hence the proposition, hold true. It is our finding that there is a reasonable condition, namely when all features are independent given the class variable (as assumed by the popular naive Bayes classifier), under which the assumptions as required by Sotoca and Pla's framework hold true.
► We discuss a paper by Sotoca and Pla on feature selection using mutual information. ► We show that two of the propositions in that paper are erroneous. ► We discuss the impact of these findings.
Unicellular diazotrophic cyanobacteria such as Cyanothece sp. ATCC 51142 (henceforth Cyanothece), temporally separate the oxygen sensitive nitrogen fixation from oxygen evolving photosynthesis not ...only under diurnal cycles (LD) but also in continuous light (LL). However, recent reports demonstrate that the oscillations in LL occur with a shorter cycle time of ~11 h. We find that indeed, majority of the genes oscillate in LL with this cycle time. Genes that are upregulated at a particular time of day under diurnal cycle also get upregulated at an equivalent metabolic phase under LL suggesting tight coupling of various cellular events with each other and with the cell's metabolic status. A number of metabolic processes get upregulated in a coordinated fashion during the respiratory phase under LL including glycogen degradation, glycolysis, oxidative pentose phosphate pathway, and tricarboxylic acid cycle. These precede nitrogen fixation apparently to ensure sufficient energy and anoxic environment needed for the nitrogenase enzyme. Photosynthetic phase sees upregulation of photosystem II, carbonate transport, carbon concentrating mechanism, RuBisCO, glycogen synthesis and light harvesting antenna pigment biosynthesis. In Synechococcus elongates PCC 7942, a non-nitrogen fixing cyanobacteria, expression of a relatively smaller fraction of genes oscillates under LL condition with the major periodicity being 24 h. In contrast, the entire cellular machinery of Cyanothece orchestrates coordinated oscillation in anticipation of the ensuing metabolic phase in both LD and LL. These results may have important implications in understanding the timing of various cellular events and in engineering cyanobacteria for biofuel production.
The sustainability of social–ecological systems within river deltas globally is in question as rapid development and environmental change trigger “negative” or “positive” tipping points depending on ...actors’ perspectives, e.g. regime shift from abundant sediment deposition to sediment shortage, agricultural sustainability to agricultural collapse or shift from rural to urban land use. Using a systematic review of the literature, we show how cascading effects across anthropogenic, ecological, and geophysical processes have triggered numerous tipping points in the governance, hydrological, and land-use management of the world’s river deltas. Crossing tipping points had both positive and negative effects that generally enhanced economic development to the detriment of the environment. Assessment of deltas that featured prominently in the review revealed how outcomes of tipping points can inform the long-term trajectory of deltas towards sustainability or collapse. Management of key drivers at the delta scale can trigger positive tipping points to place social–ecological systems on a pathway towards sustainable development.
In this paper, we propose a triangular prism and slit electrode pair (TPSE) and its micromechanical systems (MEMS) fabrication process for a novel micropump using electro-conjugate fluid (ECF), which ...is based on a thick photoresist (KMPR) micromold (≥ 500 μm) and nickel electroforming. ECF is a kind of functional and dielectric fluid. The strong and active jet flow of an ECF is generated between two electrodes surrounded by the ECF when a high direct-current voltage is applied to the electrode pair. The micropumps generated by the ECF jetting can be used as micro hydraulic pressure sources for soft microrobots. By substituting these ECF micropumps for bulky air compressors or hydraulic pumps utilized in soft robots, we can realize advanced soft microrobots in which the driving sources are embedded. An MEMS-based TPSE for an ECF micropump was successfully fabricated by using the proposed MEMS fabrication process. The maximum output pressure without a flow and the flow rate without a load were 24.6 kPa and 27.5 mm
3
/s, respectively, at an applied voltage of 2 kV. The experimental results show that the MEMS-fabricated TPSE is a good candidate for electrode-type ECF micropumps utilized in various applications of soft microrobots whose pressure sources are embedded inside.
Incorporating electrokinetic effects in the porochemoelastic inclined wellbore formulation and solution Nguyen, Vinh X.(The University of Oklahoma Sarkeys Energy Center Mewbourne School of Petroleum and Geological Engineering, Poromechanics Institute); Abousleiman, Youname N.(The University of Oklahoma Sarkeys Energy Center Poromechanics Institute ConocoPhillips School of Geology and Geophysics School of Civil Engineering and Environmental Science)
Anais da Academia Brasileira de Ciências,
03/2010, Letnik:
82, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The porochemoelectroelastic analytical models and solutions have been used to describe the response of chemically active and electrically charged saturated porous media such as clays, shales, and ...biological tissues. However, these attempts have been restricted to one-dimensional consolidation problems, which are very limited in practice and not general enough to serve as benchmark solutions for numerical validation. This work summarizes the general linear porochemoelectroelastic formulation and presents the solution of an inclined wellbore drilled in a fluid-saturated chemically active and ionized formation, such as shale, and subjected to a three-dimensional in-situ state of stress. The analytical solution to this geometry incorporates the coupled solid deformation and simultaneous fluid/ion flows induced by the combined influences of pore pressure, chemical potential, and electrical potential gradients under isothermal conditions. The formation pore fluid is modeled as an electrolyte solution comprised of a solvent and one type of dissolved cation and anion. The analytical approach also integrates into the solution the quantitative use of the cation exchange capacity (CEC) commonly obtained from laboratory measurements on shale samples. The results for stresses and pore pressure distributions due to the coupled electrochemical effects are illustrated and plotted in the vicinity of the inclined wellbore and compared with the classical porochemoelastic and poroelastic solutions.
Modelos analíticos poroelásticos incluindo acoplamento químico e elétrico e soluções têm sido utilizados paradescrever a resposta de meios porosos saturados ativos química e eletricamente tais como argilas, folhelhos e tecidos biológicos. Entretanto tais tentativas têm sido restritas a problemas de consolidação unidimensional os quais exibem limitações na prática não constituindo exemplos realistas para validação de soluções numéricas. Este trabalho apresenta formulações gerais dos modelos poroelásticos lineares incluindo acoplamento químico e elétrico e apresenta a solução de um problema de estabilidade de um poço perfurado através de uma formação saturada quimicamente ativa e ionizada tal como um folhelho submetido a um estado tridimensional de tensão. A solução analítica para esta geometria incorpora o acoplamento entre a deformação do sólido e o fluxo simultâneo de fluido e íons induzido pelos gradientes de poro pressão, potencial químico e potencial elétrico sob condições isotérmicas. O fluido residente na formação é modelado como uma solução eletrolítica composta de um solvente e cátions e anions dissolvidos. A abordagem analítica integra na solução o uso quantitativo da capacidade de troca catiônica (CTC) comumente obtida por medidas experimentais em amostras de folhelhos. Os resultados obtidos para as distribuições de tensões e poro pressão devido ao acoplamento eletroquímico são ilustrados e plotados na vizinhança do poço inclinado e comparados com as soluções clássicas poroelásticas com acoplamento químico.
Background: Cold plasma has many characteristics that allow for effective wound healing. Due to its efficacy, we have applied it in treating patients with severe Covid-19 who have soft tissue skin ...lesions and diseases including burns, pressure ulcers, shingles, and contact or atopic dermatitis. This study aims to assess the general characteristics of Covid-19 patients with soft tissue lesions and to conduct a fundamental evaluation of the efficacy of cold plasmamed beams in treating soft tissue wounds in patients with severe Covid-19. Methods: This prospective study was conducted on 20 severe Covid-19 patients with soft tissue lesions at the Intensive Care Center for Covid-19 of Hue Central Hospital in Ho Chi Minh City from September 25 to November 11, 2021. These patients was performed cold plasma irradiation at any stage of wound progression, including new injuries and chronic wounds. Results: Among 915 severe Covid-19 patients treated at our center, 20 patients had soft tissue lesions. Grade I, II, and III pressure ulcers accounted for 70% of the 20 cases of soft tissue lesions and 1.53% of the total patients at the time of the survey. Pressure ulcers were present in only 0.55% of patients (5/915 patients). Eleven out of 20 patients (55.0%) had lesions before admission, and 9 (45.0%) had lesions that appeared after admission. After 14 days of treatment, 14/20 patients had complete epithelialization (70%), and in 18/20 patients, wound exudation had ceased. The wounds became painless; after 3 weeks, the rashes had completely disappeared. Conclusion: The study emphasizes that irradiation with cold plasma contributes to the wound healing process. Keywords: cold plasma, COVID-19, pressure ulcers, dermatology, intensive care unit
A novel chaperone, cpSRP43, recognizes and disassembles the aggregates formed by its client proteins.
The client proteins of cpSRP43 form stable disc-shaped aggregates with the chaperone recognition ...motif displayed onthe surface.
The surface-exposed motif on the aggregate allows it to be recognized by its chaperone.
Understanding the structure and energetics of protein aggregates provides insights into the mechanism of theirDISASSEMBLY.Protein aggregation is detrimental to the maintenance of proper protein homeostasis in all cells. To overcome this problem, cells have evolved a network of molecular chaperones to prevent protein aggregation and even reverse existing protein aggregates. The most extensively studied disaggregase systems are ATP-driven macromolecular machines. Recently, we reported an alternative disaggregase system in which the 38-kDa subunit of chloroplast signal recognition particle (cpSRP43) efficiently reverses the aggregation of its substrates, the light-harvesting chlorophyll a/b-binding (LHC) proteins, in the absence of external energy input. To understand the molecular mechanism of this novel activity, here we used biophysical and biochemical methods to characterize the structure and nature of LHC protein aggregates. We show that LHC proteins form micellar, disc-shaped aggregates that are kinetically stable and detergent-resistant. Despite the nonamyloidal nature, the LHC aggregates have a defined global organization, displaying the chaperone recognition motif on its solvent-accessible surface. These findings suggest an attractive mechanism for recognition of the LHC aggregate by cpSRP43 and provide important constraints to define the capability of this chaperone.
This paper introduces a three-dimensional (3D) simulation to model the elasto-plastic deformation of ductile materials by discrete element method (DEM) using cohesive plastic beam approach. The ...Euler–Bernoulli beam theory is applied to calculate force and torque reactions of the cohesive beam bond that can account for plastic strain. In order to simulate the elasto-plastic behavior of materials, a coupled model of plasticity and damage is proposed for the cohesive beam bond. The von Mises yield criterion, a modified perfectly plastic law and an exponential damage law are implemented to simulate behaviors of ductile materials such as steel and aluminum in tensile tests. It is then further applied to investigate the ductile fracture modes such as localized shear fracture and necking phenomenon with cup-and-cone shape. Finally, the proposed DEM model using cohesive plastic beam is applied to visualize the compression test of cylindrical steel sample and wrinkle deformation of steel tube under bucking due to axial compression. This paper is the first attempt to model ductile materials by DEM with cohesive beam bond in tension, compression and buckling. All of the numerical benchmarks demonstrate the power of DEM using cohesive beam bond to model ductile materials with fracture, large deformation and elasto-plastic behavior.
To identify the speed of corneal neovascularization (CNV) after penetrating keratoplasty (PK) and to evaluate the influence of surgery-related factors on postkeratoplasty CNV in keratoconus patients.
...Prospective, longitudinal, observational, case series study.
All consecutive primary PKs performed for keratoconus by four experienced surgeons between January 1, 2000 and December 31, 2002 at our department were included (n = 66 patients). Standardized corneal photographs taken preoperatively and at 6 weeks, 3, 6, 12, 18, and 24 months postoperatively were evaluated. Limbus suture distance (LSD), limbus graft distance (LGD), inner suture angle (ISA), and maximal extension of CNVs in digitized pictures with 100-fold magnification were measured at each of the 16 suture turning points at every timepoint.
Forty-four (67%) out of 66 corneal grafts developed some degree of CNV after PK, most commonly from around the 12 o’clock position. The mean speed of CNV growth was 114 μm/month with the fastest growth occurring during the first six weeks after PK. There was an inverse correlation between CNV and LSD, LGD, and ISA (all
P < .001). Ninety percent of all CNVs developed with LSD < 406 μm and with LGD < 1000 μm. Superior limbal localization between 11 and 1 o’clock is an independent risk factor for postoperative neovascularization, too (
P < .001).
Small LSD, small LGD, and narrow stitching with small ISA were identified as potentially modifiable surgical risk factors for CNV after PK. The speed of CNV outgrowth was most pronounced in the first weeks after PK making early postoperative controls for CNV growth and initiation of antiangiogenic treatment important.
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