bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of 1,2,3-triazole containing compounds as potential antimicrobial agents
Authors: Bezold Elise L. , Kempton Robert J. , Green Keith D. , Hensley Ramey W. , Gilliam Olivia K. , Garneau-Tsodikova Sylvie , Onorato Amber J.
Published: July 2024

Invasive fungal infections are increasing worldwide due to an expanding number of immunocompromised patients as well as an increase in drug-resistant fungi. While fungal resistance has increased, this resistance has not been accompanied by the development of new antifungals. A common class of antifungal agents that are prescribed are the azoles, which contain either a triazole or an imidazole group. Unfortunately, current azoles, like fluconazole, have been shown to be less effective with the increase in resistant fungal pathogens. Therefore, the development of novel azole antifungal compounds is of urgent need. The objective of this research was to synthesize triazole-containing small molecules with potent antifungal activity. The scaffold of the synthesized compounds contains a triazole moiety and was synthesized via a copper-catalyzed azide-alkyne click reaction (CuAAC) between the appropriate alkyne and azide intermediates. The minimum inhibitory concentrations of these compounds were determined using standard broth microdilution assays against opportunistic bacteria and fungi associated with life-threatening invasive fungal infections. Although the synthesized compounds possessed no antimicrobial activity, these results can be used to further the long-term goal of developing and optimizing lead compounds with potent in vitro antifungal activity.
Growth Dynamics in a Mechanical Model of Cellular Colonies
Authors:   , Álvarez Murphy Fidel Gerardo
Published: July 2024

Cellular colonies are structures of microorganisms that remain attached toeach other and/or to a surface. To study the effects of mechanical stress on thedynamics of a growing colony, a minimal discrete physical model of these cellu-lar systems is proposed considering only microscopic quantities from mechanicalforces, and a cell growth and division process. Using simulations that model thediscrete model evolution, macroscopic dynamics of contact and growth withinnon-motile circular-shaped cell colonies are successfully reproducible. To find alink between the microscopic quantities involved in the dynamics and the macro-scopic observables, an out-of-equilibrium continuum theory is developed.Theobserved dynamics in the discrete model are accurately described by the contin-uum theory at the mesoscopic limit, describing along the colony the existenceof maximum inner pressure and velocity as a function of microscopic quantities.Particularly, a constitutive relation between velocity and inter-particle overlapis found, describing that the growth dynamics of a colony are equivalent in twospatial configurations: a free and a channel-limited expansion. As a second partof this work, given the dynamics of the system, a competitive genetic surfingdynamic is studied considering two different cell strains in the channel-limitedconfiguration. The observed genetic surf shows a frequency distribution of domi-nance between strains that transits from an exponential law with exponent ´3{2to a log-normal distribution depending on the initial strain relative proportionand the channel width, suggesting that this system’s competitive dynamics canbe described by mean-field theories that describe growth processes.
Diagnostic Utility of Dermoscopy in Angiokeratoma of Fordyce: A Case Report
Authors: Rachamadugu Keerthana , Quazi Sabiha , Madke Bhushan , Domakunti Rajesh , Vangala Naga Nitya
Published: July 2024

Angiokeratomas are benign, rarely occurring vascular lesions characterised by marked ectasia of thin-walled blood vessels in the superficial dermis. Angiokeratoma of Fordyce is the second most common type. It is more frequent in men and usually presents as multiple bright red papules on the scrotum, occasionally on the penis, buttocks, and abdomen; it can also occur in females mainly over the vulvar region. Here, a case of a 70-year-old patient who presented with multiple asymptomatic elevated skincoloured lesions over the scrotal region for six months is presented. Based on the clinical and dermoscopic findings, a diagnosis of angiokeratoma of Fordyce was made. Treatment involved proper counselling and reassurance about the benign nature of Angiokeratoma.
Phytochemical Screening, In vitro Antioxidant Capacity and Nephro-protective Effects of Combined Extract of Psidium guajava and Carica papaya Leaves in Rats Intoxicated with Cadmium
Authors: Orororo O. C. , Efekemo O. , Odeghe O. B. , Clark P. D. , Awhin E. P. , Egbune E. O. , Efejene I. O.
Published: July 2024

Aim: Toxic effects arising from heavy metals and other contaminants in the environment are presently been tackled by the use of medicinal plants. Thus, this study evaluated the protective effects of combined extract of Psidium guajava and Carica papaya leaves on kidney injury occasioned by cadmium (Cd) toxicity.
Materials and Methods: Phytochemical investigation of the combined extract revealed the presence of tannins, saponins, flavonoids, triterpene, steroids, alkaloids, cardiac glycoside, anthocyanins, and anthraquinone and the the extract displayed excellent antioxidant capacity in vitro. Eighteen adult female rats were divided into three groups: Group 1 (Control, received feed and water only); Group 2 (Cadmium, received single dose of cadmium, 30mg/kg body weight at the start of the experiment) and Group 3 (Cadmium + combined leaf extract, received cadmium as in group 2 above and 200mg/kg body weight of extract, daily for two weeks).
Results: Intoxication with Cd causes significantly (p<0.05) increased in the levels of lipid peroxidation and in the activity of glutathione peroxidase. Cd intoxication also depleted glutathione (GSH), super oxide dismutase (SOD) and catalase (CAT) reserves and brought about a significant increase in serum urea, creatinine, sodium and potassium. However a significant (p<0.05) normalization in the levels of GSH, SOD, CAT, urea, creatinine, sodium and potassium was observed in Cd-intoxicated rats administered the extracts as compared to the control (untreated rats).
Conclusion: The results reveal that Cd causes nephro-toxicities manifested via lipid peroxidation, increase in serum levels of urea, creatinine, sodium and potassium ions and that the combined extract of Psidium guajava and Carica papaya leaves possess adequate antioxidant power against Cd-induced nephro-toxic effects.
Comparative Analysis of Phytoplankton Communities in Newly Inundated Ponds Using Organic and Inorganic Fertilizers
Authors: M. A. Essien-Ibok, , U. U. George, , A. M. Ituen,
Published: July 2024

A comparative study on the communities of phytoplankton in two newly inundated ponds was carried out from September 2023 to October 2023.The study was conducted in a completely random design experimental setup with two treatments, each replicated twice using organic (chicken manure) and inorganic fertilizer (di-a1mmonium phosphate fertilizer, (20:10:10) (2.5kg for each) fertilizers. Out of 1114 individuals of phytoplankton identified, 611 were from the organic fertilizer- treated tank, while 503 individuals were from the inorganic fertilizer- treated tank. The highest and the lowest phytoplankton species identified were Dactylococlopsis irregularis (79) > Phormidium tenue (53) > Ankistrodesmus falcatus (39) for the organic fertilized tank while the dominant species for the inorganic tank were Dactylococlopsis irregularis (45) > Ankistrodesmus falcatus (36), > Dinobryon bararicum (31). The least dominant species found in this current study for organic fertilizer were Closterium macilentum (7) > Amoeba polypodia (7) > Volvox aureus (3) > Raphidiopsis curvata (2) while the trend for inorganic fertilizer were Aphanizomenon flosaquae (7) > Spirulina subtilissima (4) > Nitzschia linearis (2). Physicochemical factors like Temperature, pH, Potassium, Total nitrogen, were found to be the important factors influencing the growth and distribution of phytoplankton and they exhibited significant positive correlation with phytoplankton in the PCA and CCA biplot. This present study revealed inter-tank differences in some of the physico-chemical parameters investigated. Potassium, phosphorus, nitrogen and dissolved oxygen (DO) were significantly different across the two treatments while temperature and pH were not statistically significant (P<0.05). The result from the analysis of all community parameters (Shannon-Wiener diversity, Evenness, Simpson and Margalef indices) showed slight variation. The highest in Shannon-Wiener diversity, Evenness, Simpson and Margalef indices were found in the inorganic fertilizer- treated tank (3.216, 0.8901, 0.956 and 4.34, respectively), while the lowest were found in the organic fertilize treated tank (3.141, 0.825, 0.948 and 4.209, respectively). This result indicates that the abundance and structure of phytoplankton communities were affected by the different fertilizer used and the tanks physicochemical conditions.
Clinical Manifestations of Dermatophytoses and its Treatment: A Review
Authors: Meena Sumit , Bhadauria Seema
Published: July 2024

Dermatophytes can invade the keratinized tissue and cause one of the most common fungal infections, dermatophytoses. Dermatophytoses are present worldwide and it is most common in warm climates. It is caused by dermatophytes that belong to the genera Trichophyton, Epidermophyton and Microsporum. The clinical manifestation and clinical signs of these infections vary according to the infected body part and the specific dermatophytic species. According to the parts of the body that is affected, clinical manifestations of the dermatophytoses are categorized, such as tinea capitis (scalp), tinea barbae (beard area), tinea corporis (skin other than the bearded area, scalp, hands or feet), tinea cruris (groin and perineal areas), tinea pedis (feet), tinea manuum (hands), and tinea unguium (nails). Trichophyton rubrum, T. mentagrophytes, T. tonsurans, Epidermophyton floccosum and Microsporum canis are the main etiological species for dermatophytoses in all over the world. In this review, we discuss the clinical manifestations of dermatophytoses, etiological agents and their treatment by using oral and topical antifungals.
Enhancing Flood Risk Management: A Comparative Study of Regional Frequency Models in the Upper Meghna River, Bangladesh
Authors: Islam Md. Touhidul , Jahan Nusrat , Das Nilima , Abir Md. Asibur Rahman , Ferdaus Abdullah Al , Islam M. Shafiul , Rahman Mohammed Mizanur , Adham A.K.M.
Published: July 2024

Flood risk management is essential in Bangladesh, frequently affected by severe flooding due to its location at the confluence of the Ganges, Brahmaputra, and Meghna rivers. This study assesses the effectiveness of Gumbel and Log-Pearson Type III (LP3) probability distributions for flood frequency analysis at the Bhairab Bazar station in the Upper Meghna River. Using 32 years (1990-2021) of annual peak discharge data from the Bangladesh Water Development Board, flood magnitudes were predicted for various return periods. The Gumbel distribution predicted discharges from 10,709.71 m³/s for a 2-year return period to 24,519.62 m³/s for a 200-year return period, while LP3 estimates ranged from 10,701.51 m³/s to 22,911.84 m³/s for the same periods. The peak over threshold (POT) approach yielded higher discharge estimates, showing its sensitivity to extreme events. For a 200-year return period, the Gumbel-POT and LP3-POT estimates were 22,117.40 m³/s and 21,964.07 m³/s, respectively. Goodness-of-fit tests, including Kolmogorov-Smirnov, Anderson-Darling, and Chi-squared, favored the LP3 distribution for both extreme value series (EVS) and POT data, especially in critical tail regions. A rating curve was also developed using the generalized reduced gradient algorithm to better understand the river's hydraulic behavior. These findings are crucial for local flood management strategies. Discharges exceeding critical thresholds, like the 5.8-m danger level and 6.8-m severe flood level, highlight the need for robust measures. This analysis offers essential insights for designing hydraulic structures, planning flood mitigation, and improving prediction models to enhance flood risk assessments in the Upper Meghna River basin.
Role of Antioxidants in the Management of Chilli Leaf Curl Virus in Chilli Using Beneficial Fungal Root Endophyte Piriformospora indica
Authors: V. Meera Nair , N. S. Radhika , Johnson Joy Michal , P. K. Sajeesh , P. Sainamole Kurian , N. K. Binitha , Abinaya B.
Published: July 2024

Chilli leaf curl virus disease caused by Chilli leaf curl virus (ChiLCV) is considered as the most damage-causing for chilli crop, resulting in a cent per cent yield loss when affected at the early crop stage. Piriformospora indica (synonym Serendipita indica), a root endophytic fungus, enhances plant resilience against biotic and abiotic stresses. This study analyses the effect of P. indica against ChiLCV as a pot culture study under green net house conditions using Completely Randomized Design (CRD) layout in the Department of Plant Pathology, College of Agriculture, Padannakkad from August 2022 to January 2023. Chilli seeds colonized in P. indica-enriched potting mixtures exhibited earlier germination than non-colonized seeds. ChiLCV was introduced to chilli plants pre and post-colonized with P. indica and observed for disease incidence. Chlamyodspores of P. indica were observed in the root cortical region five days after co-cultivation (DAC). In the two pot culture experiments conducted, plants pre-colonized with P. indica followed by graft transmission of the virus after 15 days expressed a low vulnerability index (V.I. - 25) against non-colonized, grafted plants (V.I. – 64). Colonization of P. indica (2 days) after graft transmission of the virus recorded a V.I. (36), while non-colonized grafted plants recorded a V.I. of 65. The endophyte colonized plants exhibited elevated ROS scavenging enzyme activity (Catalase, Peroxidase, Superoxide dismutase and Phosphatase) compared to non-colonized ones which was confirmed by enzyme activity analyses and ROS staining techniques. Endophyte colonized chilli plants had exhibited more resilience towards ChiLCV thereby proving that it could be exploited in future towards cultivating disease resistant plants. This study underscores the role of P. indica in managing chilli leaf curl disease by boosting ROS-scavenging enzyme production, offering a promising avenue for disease mitigation.
Hypercyclicity Criterion on Basic Elementary Operator
Authors: Esther Kawira , King’ang’I Denis N. , Musundi Sammy W.
Published: July 2024

Hypercyclicity criterion has been an important tool in the test of hypercyclicity of different operators. This tool has been used by different mathematicians to show that generalized derivations, left and right multiplication operators, operator algebra and backward shift operators are hypercyclic. In the current paper we show that a basic elementary operator satisfies the hypercyclicity Criterion.
Tooth Discoloration Induced by Calcium Silicate-based Sealers
Authors: Alencar David Saldanha de Brito , Batista Larissa Carvalho Novaes , Crivelari Jaqueline Martins , Abreu Andre Luiz Almeida de , Leutz Anna Carolina Neves , Braido Arian , Soares Leandro Ferreira Frade , Guimarães Bruno Martini , Marciano Marina Angélica
Published: July 2024

Aims: The propose of this study was to evaluate, using spectrophotometric analysis, the change in tooth color induced by different calcium silicate-based sealers over the period of 24 hours and 30 days.
Methodology: Sixty bovine teeth were sectioned in enamel-dentin blocks. They were filled with AH Plus Bioceramic, AH Plus Jet, Bio-C Sealer and BioRoot RCS and sealed with composite. Triple antibiotic paste and unfilled samples were positive and negative control groups, respectively. Specimens were stored in separate flasks immersed in tap water at 37ºC with ambient light block out. Spectrophotometric analysis for color assessment was performed at different periods, before filling, 24 hours, and 30 days after filling. Luminosity (L) and color change ( ) were calculated. The statistical analysis was performed by using ANOVA and Tukey’s test (P < 0.05).
Results: All calcium silicate-based sealers exhibited high color alteration after the evaluated period of 30 days and showed statistically significant difference values of  in relation with the negative control in the period of 30 days (P < 0.05). Luminosity was not affected in comparison with negative control, in both evaluated periods (P < 0.05).
Conclusion: All tested sealers showed certain levels of tooth discoloration. Calcium silicate-based sealers (AH Plus Bioceramic, Bio-C Sealer, and BioRoot RCS) presented discoloration exceeding acceptable values within a 30-day follow-up. Notwithstanding, these alterations were imperceptible to the human eye.
Proanthocyanidins and Dental Health: Uncovering the Benefits
Authors: Baskar Rajeshwari , Srinivasan Daya
Published: July 2024

Proanthocyanidins (PAs) are a subclass of flavonoids that are widely distributed in different plant sources and have attracted interest due to their potential health advantages, especially in maintaining dental health. The purpose of this review is to better understand the properties and applications of proanthocyanidins in maintaining dental health. Proanthocyanidins have excellent antibacterial, anti-inflammatory, and antioxidant qualities that are vital for preventing oral illnesses such oral cancer, periodontal disorders, and dental caries. Furthermore, PAs have demonstrated efficacy in augmenting salivary flow, and encouraging tooth enamel remineralization. Moreover, proanthocyanidins are low in toxicity and have good biocompatibility, which makes them good choices for adding to a variety of mouthwash, toothpaste, and dental materials. Their minimal side effects and natural source make them even more desirable for use in oral health interventions. However, Further research is needed to fully investigate their therapeutic potential and optimize their use in preventive and treatment methods for oral diseases.
Drug-induced Cornea Verticillata: A Report of 2 Cases
Authors: Bouzidi Adil , Mhadi Mohcine El , Ouafi Aziz El
Published: July 2024

Cornea verticillata is caused by the deposition of drugs, metabolic substrates, or disease byproducts in the basal epithelial layer of the cornea, it is most associated with amiodarone and Fabry disease. It can also be caused by a variety of other drugs, the most common of which are: Chloroquine and Hydroxychloroquine, Indomethacin, Phenothiazines.
We report two cases of drugs induced cornea verticillata, one secondary to prolonged intake of amiodarone and the other to amiodarone and hydroxychloroquine, to understand its pathophysiology, describe its clinical classification and discuss its treatment.
The medications that cause this pathology have similar cationic and amphiphilic characteristics that enable them to penetrate the cornea's basal epithelial layer lysosomes and attach to cellular lipids there. These drug-lipid complexes build up as deposits in the cornea and are resistant to enzymatic breakdown. The deposits are generally not visually significant and generally disappear with the cessation of the causative agent. Several case reports have described resolution of whorled cornea with the use of topical heparin.
Event‐specific chorus wave and electron seed population models in DREAM3D using the Van Allen Probes
Authors: Tu Weichao , Cunningham G. S. , Chen Y. , Morley S. K. , Reeves G. D. , Blake J. B. , Baker D. N. , Spence H.
Published: February 2014

The DREAM3D diffusion model is applied to Van Allen Probes observations of the fast dropout and strong enhancement of MeV electrons during the October 2012 “double‐dip” storm. We show that in order to explain the very different behavior in the two “dips,” diffusion in all three dimensions (energy, pitch angle, and L*) coupled with data‐driven, event‐specific inputs, and boundary conditions is required. Specifically, we find that outward radial diffusion to the solar wind‐driven magnetopause, an event‐specific chorus wave model, and a dynamic lower‐energy seed population are critical for modeling the dynamics. In contrast, models that include only a subset of processes, use statistical wave amplitudes, or rely on inward radial diffusion of a seed population, perform poorly. The results illustrate the utility of the high resolution, comprehensive set of Van Allen Probes' measurements in studying the balance between source and loss in the radiation belt, a principal goal of the mission.
Analytic expressions for ULF wave radiation belt radial diffusion coefficients
Authors: Ozeke Louis G. , Mann Ian R. , Murphy Kyle R. , Jonathan Rae I. , Milling David K.
Published: February 2014

We present analytic expressions for ULF wave‐derived radiation belt radial diffusion coefficients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefficients are derived from statistical representations of ULF wave power, electric field power mapped from ground magnetometer data, and compressional magnetic field power from in situ measurements. We show that the overall electric and magnetic diffusion coefficients are to a good approximation both independent of energy. We present example 1‐D radial diffusion results from simulations driven by CRRES‐observed time‐dependent energy spectra at the outer boundary, under the action of radial diffusion driven by the new ULF wave radial diffusion coefficients and with empirical chorus wave loss terms (as a function of energy, Kp and L). There is excellent agreement between the differential flux produced by the 1‐D, Kp‐driven, radial diffusion model and CRRES observations of differential electron flux at 0.976 MeV—even though the model does not include the effects of local internal acceleration sources. Our results highlight not only the importance of correct specification of radial diffusion coefficients for developing accurate models but also show significant promise for belt specification based on relatively simple models driven by solar wind parameters such as solar wind speed or geomagnetic indices such as Kp.
Energetics and geographic distribution of elve‐producing discharges
Authors: Chen Alfred Bing‐Chih , Su Han‐Tzong , Hsu Rue‐Ron
Published: February 2014

The major types of transient luminous events (TLEs) are believed to be directly triggered by cloud‐to‐ground discharges. Intense lightning generally seems to have a higher production efficiency for TLEs, but this observation has not yet been statistically investigated. Two data sets, the upgraded World Wide Lightning Location Network (WWLLN) lightning stroke data and the Imager of Sprites and Upper Atmospheric Lightning (ISUAL) TLE data, were used to investigate the energetics and the geographic distribution of TLE‐producing lightning. The global median energy of the strokes that produced the TLEs is at least an order of magnitude higher than the global median stroke energy for WWLLN lightning in the same data window. Furthermore, the energy distributions of the elve‐producing strokes exhibit no oceanic and land disparity. These results reveal that the elves are indeed triggered by energetic lightning and the production efficiency of elves with respect to the stroke energy of the causative lightning was insensitive to the underlying landform. Analysis of the spatial correlation between the ISUAL elves and the WWLLN lightning reveals that the geographic distribution of the ISUAL elves agreed well with that for the most energetic 10% of the WWLLN lightning strokes, better than for total lighting. We also found that elve occurrence rates in the apparently reduced detection regions behind the Earth's limb may have been greatly underestimated, partially due to the failure in providing triggers to initiate ISUAL recording or the severity of atmospheric attenuation to the elve emissions that may have caused them to be undetected.
Intensification and variability of the confluence of subtropical and subantarctic boundary currents east of New Zealand
Authors: Fernandez D. , Bowen M. , Carter L.
Published: February 2014

The confluence of subtropical and subantarctic boundary currents east of New Zealand creates strong fronts. The fronts have clear signatures in sea surface height (SSH) and sea surface temperature (SST) which make the confluence a good region to investigate the variability of the boundary currents of the South Pacific. Analysis of the 20 year time series of the SSH is used to investigate the location and strength of fronts, measured as the gradient in SSH (∇SSH), and the eddy kinetic energy (EKE) and their relationship to local and large‐scale wind forcing. The intensity of the ∇SSH and the EKE have increased at a rate of 0.02 cm km−1 and 32 cm2 s−2 decade−1, respectively. There is a significant correlation (r = 0.7, p < 0.01) between the ∇SSH and EKE signals, reflecting baroclinic instabilities inherent in the fronts. Differences between northward and southward wind‐driven transports across the confluence from the Island Rule are also increasing at 7.5 Sv decade−1 along with an upward trend in the SST differences across the region. Time series of the Southern Annular Mode (SAM) and Southern Oscillation Index (SOI) and local winds were compared to the frontal strength. Although the positive trend in the SOI coincides with increasing subtropical inflows, there is little correspondence of the indices and local winds with short‐term variability. While these results indicate a connection between the intensification of the confluence and South Pacific winds, there is little change in frontal location north of Bollons Seamount which suggests bathymetry influences the location of the confluence.
Eddies and an extreme water mass anomaly observed in the eastern south Pacific at the Stratus mooring
Authors: Stramma Lothar , Weller Robert A. , Czeschel Rena , Bigorre Sebastien
Published: February 2014

In the tropical eastern South Pacific the Stratus Ocean Reference Station (ORS) (∼20°S, 85.5°W) is located in the transition zone between the oxygen minimum zone (OMZ) and the well‐oxygenated subtropical gyre. In February/March 2012, extremely anomalous water mass properties were observed in the thermocline at the Stratus ORS. The available eddy oxygen anomaly was −10.5 × 1016 µmol. This anomalous water was contained in an anticyclonic mode‐water eddy crossing the mooring site. This eddy was absorbed at that time by an anticyclonic feature located south of the Stratus mooring. This was the largest water property anomaly observed at the mooring during the 13.5 month deployment period. The sea surface height anomaly (SSHA) of the strong mode‐water eddy in February/March 2012 was weak, and while the lowest and highest SSHA were related to weak eddies, SSHA is found not to be sufficient to specify the eddy strength for subsurface‐intensified eddies. Still, the anticyclonic eddy, and its related water mass characteristics, could be tracked backward in time in SSHA satellite data to a formation region in April 2011 off the Chilean coast. The resulting mean westward propagation velocity was 5.5 cm s−1. This extremely long‐lived eddy carried the water characteristics from the near‐coastal Chilean water to the open ocean. The water mass stayed isolated during the 11 month travel time due to high rotational speed of about 20 cm s−1 leading to almost zero oxygen in the subsurface layer of the anticyclonic mode‐water eddy with indications of high primary production just below the mixed layer.
Cyclogeostrophic balance in the Mozambique Channel
Authors: Penven Pierrick , Halo Issufo , Pous Stéphane , Marié Louis
Published: February 2014

Three methods are proposed for the inclusion of inertia when deriving currents from sea surface height (SSH) in the Mozambique Channel: gradient wind, perturbation expansion, and an iterative method. They are tested in a model and applied to satellite altimetry. For an eddy of 25 cm amplitude and 100 km radius, typical of Mozambique Channel rings at 18°S, the error made with geostrophy is 40% for the anticyclones and 20% for the cyclones. Inertia could reach one third of the pressure gradient. Geostrophy underestimates subsurface currents by up to 50 cm s−1, resulting in errors of 30–40%. The iterative method results in errors of <5% for the most part of the structure. The error RMS in velocities based on 8 years of model SSH is in excess of 30 cm s−1 for geostrophy and reduces to about 10 cm s−1 for the gradient wind and iterative methods. The perturbation method is less accurate. Applied to satellite altimetry, the addition of inertia results in a significant increase in velocities for the anticyclones and a decrease for the cyclones. It induces a velocity increase of >50% in Mozambique Channel rings. Geostrophic EKE reaches 1400 cm2 s−2, while it attains 1800 cm2 s−2 when inertia is added. Applied to the Gulf Stream, these methods confirm the hypothesis of Maximenko and Niiler [2006] that centrifugal accelerations should be the main cause for the difference observed between geostrophic and drifter EKE. This methodology should result in a net improvement for operational surface ocean currents.
Microencapsulated Carbon Black Suspensions for Restoration of Electrical Conductivity
Authors: Kang Sen , Jones Amanda R. , Moore Jeffrey S. , White Scott R. , Sottos Nancy R.
Published: February 2014

Robust microcapsules are prepared with carbon black suspensions high in solids loading (up to 0.2 g/mL) for electrical conductivity restoration. Oxidized carbon black is rendered more hydrophobic through surface functionalization with octadecylamine by two different methods. Functionalization significantly improves dispersability and suspension stability of carbon black in hydrophobic solvents such as o‐dichlorobenzene (o‐DCB), enabling encapsulation by in situ emulsion polymerization. Upon crushing, microcapsules containing functionalized carbon black (FCB) suspensions exhibit significant particle release relative to microcapsules filled with unfunctionalized carbon black. Release of carbon black is further enhanced by the addition of two types of core thickeners, epoxy resin or poly 3‐hexylthiophene (P3HT). Full conductivity restoration (100% restoration efficiency) of damaged silicon anodes is achieved by crushing microcapsules containing FCB suspensions with P3HT. Hydrophobic surface functionalization of carbon black and the addition of core thickeners are both critical for achieving stable microcapsules capable of significant particle release and efficient conductivity restoration.
Soft Actuators and Robots that Are Resistant to Mechanical Damage
Authors: Martinez Ramses V. , Glavan Ana C. , Keplinger Christoph , Oyetibo Alexis I. , Whitesides George M.
Published: February 2014

This paper characterizes the ability of soft pneumatic actuators and robots to resist mechanical insults that would irreversibly damage or destroy hard robotic systems—systems fabricated in metals and structural polymers, and actuated mechanically—of comparable sizes. The pneumatic networks that actuate these soft machines are formed by bonding two layers of elastomeric or polymeric materials that have different moduli on application of strain by pneumatic inflation; this difference in strain between an extensible top layer and an inextensible, strain‐limiting, bottom layer causes the pneumatic network to expand anisotropically. While all the soft machines described here are, to some extent, more resistant to damage by compressive forces, blunt impacts, and severe bending than most corresponding hard systems, the composition of the strain‐limiting layers confers on them very different tensile and compressive strengths.
Biodegradable Thermogelling Polymers: Working Towards Clinical Applications
Authors: Dou Qing Qing , Liow Sing Shy , Ye Enyi , Lakshminarayanan Rajamani , Loh Xian Jun
Published: February 2014

As society ages, aging medical problems such as organ damage or failure among senior citizens increases, raising the demand for organ repair technologies. Synthetic materials have been developed and applied in various parts of human body to meet the biomedical needs. Hydrogels, in particular, have found extensive applications as wound healing, drug delivery and controlled release, and scaffold materials in the human body. The development of the next generation of soft hydrogel biomaterials focuses on facile synthetic methods, efficacy of treatment, and tunable multi‐functionalities for applications. Supramolecular 3D entities are highly attractive materials for biomedical application. They are assembled by modules via various non‐covalent bonds (hydrogen bonds, p–p stacking and/or van der Waals interactions). Biodegradable thermogels are a class of such supramolecular assembled materials. Their use as soft biomaterials and their related applications are described in this Review.
A Review of Graphene‐Based Nanostructural Materials for Both Catalyst Supports and Metal‐Free Catalysts in PEM Fuel Cell Oxygen Reduction Reactions
Authors: Zhou Xuejun , Qiao Jinli , Yang Lin , Zhang Jiujun
Published: February 2014

A comprehensive overview and description of graphene‐based nanomaterials explored in recent years for catalyst supports and metal‐free catalysts for polymer electrolyte membrane (PEM) fuel cell oxygen reduction reactions (ORR) is presented. The catalyst material structures/morphologies, material selection, and design for synthesis, catalytic performance, catalytic mechanisms, and theoretical approaches for catalyst down‐selection and catalyzed ORR mechanisms are emphasized with respect to the performance of ORR catalysts in terms of both activity and stability. When graphene‐based materials, including graphene and doped graphene, are used as the supporting materials for both Pt/Pt alloy catalysts and non‐precious metal catalyst, the resulting ORR catalysts can give superior catalyst activity and stability compared to those of conventional carbon‐supported catalysts; when they are used as metal‐free ORR catalysts, significant catalytic activity and stability are observed. The nitrogen‐doped graphene materials even show superior performance compared to supported metal catalysts. Challenges including the lack of material mass production, unoptimized catalyst structure/morphology, insufficient fundamental understanding, and testing tools/protocols for performance optimization and validation are identified, and approaches to address these challenges are suggested.
Reaction performance of isobutane alkylation catalyzed by a composite ionic liquid at a short contact time
Authors: Liu Zhichang , Meng Xianghai , Zhang Rui , Xu Chunming , Dong Heng , Hu Yufeng
Published: February 2014

Alkylate is an important clean blending component of gasoline due to the increased statutory reduction of the content of aromatics and olefins in commercial gasoline. The alkylation of isobutane with 2‐butene catalyzed by a composite ionic liquid was investigated. The composite ionic liquid showed efficient catalytic performance at a short contact time (10–60 s). The optimal conditions were: reaction temperature 15°C, contact time 20 s, ionic liquid to hydrocarbon volume ratio 1:1, and isobutane to olefin mole ratio 54:1. Under these optimal reaction conditions, the butene conversion was 100%, the yields of C8 and trimethylpentanes were 88.9 and 82.0%, respectively, the ratio of trimethylpentane to dimethylhexane was 11.9, and the alkylate research octane number (RON) was 97.3. A correlation model is developed to predict the product yields and the alkylate RON. The correlation model shows a low calculation error. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2244–2253, 2014
Numerical investigation on the number of active surface sites of carbon catalysts in the decomposition of methane
Authors: Younessi‐Sinaki Maryam , Hamdullahpur Feridun
Published: February 2014

The number of active sites on the surface of carbon catalysts is an important factor in determining their activity in the decomposition of methane. Although several studies have been performed to identify the nature of these sites, no method has been established to estimate their number. A method is presented to estimate this value, and its effect on hydrogen production is evaluated, along with that of temperature and residence time. For this purpose, the thermocatalytic decomposition of methane is modeled with the inclusion of the number of active sites of the catalyst in the kinetics. The results of the model indicate the high influence of variations of small residence times in this process, and the reduction of this effect at high temperatures. Also, the effect of the number of surface sites is shown to be more prominent at low residence times and temperatures. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2228–2234, 2014
Ensembles‐based and GA‐based optimization for landfill gas production
Authors: Li Hu , Tsotsis Theodore T. , Sahimi Muhammad , Qin S. Joe
Published: February 2014

The efficient and economic production of landfill gases (LFG) by optimally adjusting LFG production settings is of high interest as a promising source of biomass energy. A key obstacle in LFG production optimization is the large‐scale and complex system with overwhelming uncertainty and heterogeneity. We propose a simplified ensemble‐based optimization (EnOpt) method to solve the LFG production optimization problem when constraints are not a concern, where the gradient information is obtained from an ensemble of realizations of the system. For constrained optimization, a novel parameterless genetic algorithm is proposed and successfully applied to the simulated LFG process. The effectiveness of the proposed (EnOpt) method and the parameterless genetic algorithm is demonstrated with the simulation of a landfill and gas generation and transport therein, using a parallel computation strategy. © 2014 American Institute of Chemical EngineersAIChE J, 60: 2063–2071, 2014
Dynamic mechanical properties of three‐component composites (acrylic polymer/epoxy/SiO2) in the glass‐transition region
Authors: Uematsu Hideyuki , Nishimoto Takashi , Tanoue Shuichi , Iemoto Yoshiyuki , Aoki Yuji , Sugimoto Masataka , Koyama Kiyohito
Published: February 2014

In previous studies, we reported the linear and nonlinear rheological properties of three‐component composites consisting of acrylic polymer (AP), epoxy resin (EP), and various SiO2 contents (AP/EP/SiO2) in the molten state. In this study, the dynamic mechanical properties of AP/EP/SiO2 composites with different particle sizes (0.5 and 8 μm) were investigated in the glass‐transition region. The EP consisted of three kinds of EP components. The α relaxation due to the glass transition shifted to a higher temperature with an increase in the volume fraction (ϕ) for the AP/EP/SiO2 composites having a particle size of 0.5 μm, but the α relaxation scarcely shifted for the composite having a particle size of 8 μm as a general result. This result suggested that the SiO2 nanoparticles that were 0.5 μm in size adsorbed a lot of the low‐glass‐transition‐temperature (Tg) component because of their large surface area. The AP/SiO2 composites did not exhibit a shift in Tg; this indicated that the composite did not adsorb any component. The modulus in the glassy state (E′g) exhibited a very weak &phis; dependence for the AP/EP/SiO2 composites having particle sizes of 0.5 and 8 μm, although E′g of the AP/SiO2 composites increased with &phis;. The AP/EP/SiO2 composites exhibited a peculiar dynamic mechanical behavior, although the AP/SiO2 composites showed the behavior of general two‐component composites. Scanning electron microscopic observations indicated that some components in the EP were adsorbed on the surface of the SiO2 particles. We concluded that the peculiar behavior of the AP/EP/SiO2 composites was due to the selective adsorption of the EP component. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40409.
Structural, mechanical, thermal, and electrical properties of carbon black reinforced polyester resin composites
Authors: Alam M. K. , Islam M. T. , Mina M. F. , Gafur M. A.
Published: February 2014

Carbon black (CB) reinforced polyester resin (PR) composites (CPC) have been fabricated from mechanical mixtures of liquid PR and CB powder having 0–50 wt% CB contents and cured with 1% of methyl ethyl ketone peroxide at room temperature under a pressure of 50 MPa. The samples have been examined by the Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD) technique, scanning electron microscopy (SEM), mechanical test, micromechanical test, differential thermal analysis (DTA), and thermogravimetric analysis (TGA) and electrical test. FTIR spectra confirm the physical and chemical bond formations between CB and PR. XRD shows a very partial crystalline structure in cured PR and hexagonal structure in CB particles. SEM exhibits a clear dispersion of CB particles in PR matrix at lower loading and aggregates at higher loading. With the increase of fillers, while the tensile and flexural strengths of CPCs decrease, the Young's and tangent modulii increase by 80 and 100%, respectively. These increments are found consistent with the theoretical values. The degree of physical crosslinking between CB and PR as well as the aspect ratio of CB in CPCs are found to increase with the increase of filler. A remarkable increase in microhardness of about 61% at 50 wt% CB content is observed. The TGA represents that the thermal degradation temperature for pure PR is 373°C and that for CPC is 393°C. The dielectric constant of CPCs decreases with increasing frequency, whereas the ac‐ and dc‐ conductivities of CPC are found to increase with CB content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40421.
Novel fabrication route for porous silicon carbide ceramics through the combination of in situ polymerization and reaction bonding techniques
Authors: Ebrahimpour Omid , Esmaeili Babak , Griffon Lucie , Chaouki Jamal , Dubois Charles
Published: February 2014

For the first time, an in situ polymerization technique was applied to produce mullite‐bonded porous SiC ceramics via a reaction bonding technique. In this study, SiC microsized particles and alumina nanopowders were successfully coated by polyethylene (PE), which was synthesized from the particle surface in a slurry phase reactor with a Ziegler–Natta catalyst system. The thermal studies of the resulting samples were performed with differential scanning calorimetry and thermogravimetric analysis. The morphology analysis obtained by transmission electron microscopy and scanning electron microscopy (SEM) confirmed that PE was successfully grafted onto the particle surface. Furthermore, the obtained porous ceramics were characterized in terms of their morphologies, phase composition, open porosity, pore size distribution, and mechanical strength. SEM observations and mercury porosimtery analysis revealed that the quality of the dispersion of nanosized alumina powder into the microsized SiC particles was strongly enhanced when the particles were coated by polymers with in situ polymerization. This resulted in a higher strength and porosity of the formed ceramic porous materials with respect to the traditional process. In addition, the X‐ray diffraction results reveal that the amount of mullite as the binder increased significantly for the samples fabricated by this novel method. The effects of the sintering temperature, forming pressure, and polymer content on the physical and mechanical properties of the final porous ceramic were also evaluated in this study. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40425.
Ultraviolet‐crosslinked hydrogel sustained‐release hydrophobic antibiotics with long‐term antibacterial activity and limited cytotoxicity
Authors: Liu Tao , Wu Ting , Liu Hongxi , Ke Bo , Huang Hongxing , Jiang Zhenyou , Xie Mingqiang
Published: February 2014

To prolong erythromycin (EM) release and prevent the side effects of EM, a Pluronic F‐127 diacrylate macromer (PF127) was synthesized and then self‐assembled into micelles with their hydrophobic cores loaded with EM. The EM‐loaded micelles were mixed with a photoinitiator to form the EM/PF127 hydrogels rapidly under a low‐intensity UV light. Afterward, the hydrogel properties, antibacterial performance, and cytotoxicity of this novel hybrid hydrogel were investigated. The results show that the EM/PF127 hydrogel had a rapid gelation time. The sustained release of EM reduced its side effects. With controlled antibacterial activity, the use of EM would be safer and more efficient. What is more, the EM/PF127 hydrogel showed a slight cytotoxicity, and this suggests great potential application as antibacterial hydrogels in the prevention of postoperative infection. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40438.
Hybrid clay‐carbon nanotube/PET composites: Preparation, processing, and analysis of physical properties
Authors: Gorrasi Giuliana , D'Ambrosio Salvatore , Patimo Giovanni , Pantani Roberto
Published: February 2014

The aim of this work was the preparation of novel composites of poly(ethylene terephthalate) (PET) and nano‐hybrid systems based on clay used as catalyst for the growth of multi walled carbon nanotubes (Clay‐CNTs), through catalytic chemical vapor deposition (CCVD). The carbon content into the hybrid filler was 58.1 wt %. Composites with 1.0, 1.5, 2.0, 3.0 wt % of Clay–CNTs were obtained by melt compounding and processed using a microinjection molding press. Unfilled PET was processed in the same composites conditions. Structural characterization and physical properties (thermal, degradation, mechanical, and electrical) were analyzed and correlated to the hybrid filler loading, and carbon nanotubes amount. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40441.
Effect of OMMTs on flame retardancy and thermal stability of poly(ethylene‐co‐vinyl acetate)/LDPE/magnesium hydroxide composites
Authors: Masoomi Mahmood , Bagheri Rouhollah , Ahmadkhanbeigi Leila , Asgari Mohammad
Published: February 2014

The aim of this study was to prepare poly (ethylene‐co‐vinyl acetate) (EVA)/ low density polyethylene (LDPE)/magnesium hydroxide (MH) composites applicable in cable industry with required flame retardancy. For this reason, two types of organo‐modified montmorillonites (OMMT) with different surface polarites (Cloisite 15A and Cloisite 30B) at various concentrations, and also combination of these two OMMTs with overall loadings of 2 wt % and 5 wt % were used. The samples were compounded using a twin screw extruder with total (MH + OMMT) feeding of 55 wt % and 60 wt %. Limiting oxygen index (LOI) of the samples containing 2 wt % of OMMTs increased about 16% and dripping was suppressed according to vertical burning test (UL‐94V). Thermogravimetric results of EVA/LDPE/MH samples containing OMMT showed that the beginning of second step degradation was shifted about 50°C to higher temperatures. The composite tensile strength results showed enhancement by incorporating some amount of nanoclays with EVA/LDPE/MH composites. Scanning electron microscopy images confirmed that MH particles had better wetting by EVA matrix in presence of nanoclays. Oxidative induction time of the EVA/LDPE/MH/OMMT nanocomposites was 140 min, which was more than that of the samples without OMMT (20 min). Employing the equal weight ratios of the two OMMTs demonstrated a synergistic effect on flame retardancy of the samples according to the both tests results (LOI, UL‐94V). X‐ray diffraction analysis of the samples confirmed the intercalation/semiexfoliation structure of nanosilicate layers in the bulk of EVA/LDPE matrix. This led to longer elongation at break and thermal stability of Cloisite 15A based nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40452.