bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of speed of action and injection discomfort of 4% articaine and 2% mepivacaine for pulpal anesthesia in mandibular teeth: A randomized, double-blind cross-over trial
Authors: Gazal Giath
Published: May 2015

Objective: To compare the injection pain and speed of local anesthetic effect induced by tissue infiltration of mepivacaine 2% with epinephrine 1:100,000 versus articaine 4% with epinephrine 1:100,000 in securing mandibular first molar pulp anesthesia. Materials and Methods: Totally, 25 patients were recruited in a crossover, randomized, double-blind study. Each subject received injections of mepivacaine 2% with epinephrine 1:100,000 as inferior alveolar nerve block (IANB) supplemented with either articaine 4% with epinephrine 1:100,000 (septocaine) or mepivacaine 2% buccal infiltration (BI) injection on two visits. The time of first numbness to associated lip, tongue and tooth was recorded by asking the participant directly and using electrical pulp tester. Anesthetic success was considered when two consecutive maximal stimulation on pulp testing readings without sensation. The patients rated the pain of infiltration using a 100 mm visual analog scale immediately after receiving each injection. The pain scores were compared using the paired t-test. Results: There were significant differences in the meantime of first numbness to associated lip and tooth of volunteers between mepivacaine and articaine BI groups P = 0.03 and 0.002. Volunteers in articaine group recorded earlier lip and teeth numbness than those in mepivacaine group. There were significant differences between the mean pain scores for volunteers in the post IANB and postbuccal injection groups (t-test: P <0.001). Mepivacaine IANB injection was significantly more painful than articaine/mepivacaine buccal injection. Conclusions: About 4% articaine was faster than 2% mepivacaine (both with 1:100,000 adrenaline) in anesthetizing the pulps of lower molar teeth after BIs. Earlier lip and teeth numbness were recorded in articaine group. Articaine and mepivacaine BIs were more comfortable than mepivacaine IANB injections.
Effect of silver nanoparticles incorporation on viscoelastic properties of acrylic resin denture base material
Authors: Mahross Hamada Zaki , Baroudi Kusai
Published: May 2015

Objective: The objective was to investigate the effect of silver nanoparticles (AgNPs) incorporation on viscoelastic properties of acrylic resin denture base material. Materials and Methods: A total of 20 specimens (60 × 10 × 2 mm) of heat cured acrylic resin were constructed and divided into four groups (five for each), according to the concentration of AgNPs (1%, 2%, and 5% vol.) which incorporated into the liquid of acrylic resin material and one group without additives (control group). The dynamic viscoelastic test for the test specimens was performed using the computerized material testing system. The resulting deflection curves were analyzed by material testing software NEXYGEN MT. Results: The 5% nanoparticles of silver (NAg) had significantly highest mean storage modulus E’ and loss tangent Tan δ values followed by 2% NAg (P < 0.05). For 1% nanosilver incorporation (group B), there were no statistically significant differences in storage modulus E’, lost modulus E” or loss tangent Tan δ with other groups (P > 0.05). Conclusion: The AgNPs incorporation within the acrylic denture base material can improve its viscoelastic properties.
Identifying the tooth shade in group of patients using Vita Easyshade
Authors: Elamin Habab Osman , Abubakr Neamat Hassan , Ibrahim Yahia Eltayib
Published: May 2015

Objective: The aim of the present investigation is to identify tooth shade among a group of Sudanese patients. Materials and Methods: Total number of patients was 227. Participant's age ranged from 15 to 72 years, which, was divided into four groups. The tooth included in the study was either right or left sounds maxillary central incisor. Vita Easyshade was used to select the tooth shade. Investigation of the differences of Commission International de l'Eclairage (CIELab) coordinates among gender and state of origin was conducted together with an examination of the relationship between CIELab coordinates and age. One-way analysis of variance was used to test the differences in L*, a* and b* according to state of origin. Results: Results showed that A3 was the most common classical tooth shade respectively. There was highly significant difference in L* between males and females (P = 0.002). There was a significant relation between tooth shade and age (P = 0.026). There was a high significant association between classical tooth shade and Sudan regions (P = 0.00). Conclusion: In conclusion, most common classical shade was A3, women's teeth were lighter than men's. There was a relation between ethnic background and tooth shade.
An assessment of antibacterial activity of three pulp capping materials on Enterococcus faecalis by a direct contact test: An in vitro study
Authors: Koruyucu Mine , Topcuoglu Nursen , Tuna E. Bahar , Ozel Sevda , Gencay Koray , Kulekci Guven , Seymen Figen
Published: May 2015

Objective: The aim of this in vitro study was to evaluate antimicrobial activities of three different pulp capping materials; Biodentine, mineral trioxide aggregate (MTA) Angelus, and Dycal against Enterococcus faecalis and their durability with time. Materials and Methods: Direct contact test was used for the assessment. Three sets of sealers were mixed and placed on microtiter plate wells: One set was used within 20 min of recommended setting time while others were used after 24-h and 1-week. E. faecalis suspension was placed directly on the materials for 1 h and then transferred to another plate with fresh media. Nine wells of bacteria without the tested cements served as the positive control. One well of the tested cements without bacteria served as the negative control. Bacterial growth was evaluated by a temperature-controlled microplate spectrophotometer for 1-h intervals among 24 h. Data were analyzed using Kruskal–Wallis test. Results: All tested materials showed less bacterial density than the control group. MTA, Biodentine, and Dycal showed significantly higher bacterial density than the control group in freshly mixed samples (P < 0.05). And MTA showed significantly higher antibacterial activity than Dycal (P < 0.05). In 24 h, materials did not show any differences (P > 0.05). MTA and Biodentine samples showed significant differences than Dycal; MTA also showed higher antibacterial activity than control in 1-week samples (P < 0.05). Conclusion: While freshly mixed MTA showed the best antibacterial activity over time, Biodentine had shown similar antibacterial activity to MTA.
Surgical and prosthetic management of maxillary odontogenic myxoma
Authors: Rashid Haroon , Bashir Atif
Published: May 2015

Odontogenic myxomas are uncommon tumors of comprising of 3% of all the tumors of odontogenic origin. They usually occur during the second and third decades of life and are more commonly seen in females. The current case report sheds light upon the surgical treatment of a myxoma of odontogenic origin in posterior maxilla of a young female patient. Prosthodontic rehabilitation stages are also briefly described following complete healing of the lesion after surgery.
The use of Erbium: Yttrium-aluminum-garnet laser in cavity preparation and surface treatment: 3-year follow-up
Authors: Buyukhatipoglu Isil , Secilmis Asli
Published: May 2015

From the currently available choices, esthetic restorative materials for posterior teeth are limited to composite and ceramic restoration. Ceramic inlays/onlays are reliable solutions for both of these treatments. For successful treatment planning, usable ceramic and adhesive systems should be chosen by the dentist. Since the Federal Drug Administration approval of the erbium: Yttrium-aluminum-garnet (Er:YAG) laser-for caries removal, cavity preparation and the conditioning of tooth substance-in 1997, there have been many reports on the use of this technique in combination with composite resins. In addition, cavity pretreatment with the Er:YAG laser (laser etching) has been proposed as an alternative to acid etching of enamel and dentin. This case report presents the use of the Er:YAG in cavity preparation for composite resin restoration and surface treatment for ceramic onlay restoration of adjacent permanent molars.
Effect of peroxide bleaching on the biaxial flexural strength and modulus of bovine dentin
Authors: Carvalho Adriana Oliveira , Ayres Ana Paula Almeida , de Almeida Letícia Cunha Amaral Gonzaga , Briso André Luiz Fraga , Rueggeberg Frederick Allen , Giannini Marcelo
Published: May 2015

Objective: This study evaluated the effects of carbamide peroxide and hydrogen peroxide on the biaxial flexural strength and flexural modulus of bovine dentin. Materials and Methods: Thirty coronal dentin disks (0.5 mm thick × 6.0 mm diameter) were prepared from bovine teeth. The disks were randomly divided into three groups (n=10): A control group (unbleached), a group bleached with 10% carbamide peroxide (8 h at 37°C), and a group bleached with 38% hydrogen peroxide (three 10 min applications at 37°C). The specimens were tested in a biaxial flexural apparatus held in a universal testing machine at 1.27 mm/min until failure occurred, and the biaxial mechanical properties were calculated. For each test parameter, the data were statistically analyzed by Fisher's PLSD test (predetermined ⍺ = 0.05). Results: The group bleached with 38% hydrogen peroxide demonstrated significantly lower flexural strength than the unbleached control group. Hydrogen peroxide treatment resulted in a significantly lower flexural modulus compared with the control group and with carbamide peroxide bleaching. Conclusion: Exposure of dentin to hydrogen peroxide significantly reduced both the flexural strength and the flexural modulus compared with the no-treatment control, whereas exposure to carbamide peroxide did not significantly affect either parameter.
Effect of storage solutions on microhardness of crown enamel and dentin
Authors: Aydın Berdan , Pamir Tijen , Baltaci Aysun , Orman Mehmet N. , Turk Tugba
Published: May 2015

Objective: The aim of this study was to determine alterations in microhardness of crown dentin and enamel, after 2 and 12-month storage in de-ionized water, 0.2% glutaraldehyde, Hanks’ Balanced Salt Solution (HBSS), 0.1% sodium hypochlorite (NaOCl) or 0.1% thymol. Materials and Methods: Freshly extracted, nonsterile 60 intact human premolars were distributed to five groups. Six teeth from each group were evaluated after two, and other six teeth were evaluated after 12 months storage. After grinding and polishing of teeth, Vickers hardness was evaluated with making indentations on enamel and dentin, using a pyramid diamond indenter tip exerting 100 g load for 15 s. Results: After 2 months storage in solutions, range of the hardness values (HV) of enamel and dentin were in between 315–357 and 64–67, respectively. However, 12 months storage of the teeth resulted in a statistically significant decrease in microhardness when compared to microhardness of teeth stored for 2 months (P = 0.001). Although the differences were not significant regarding solutions, all solutions decreased the microhardness both in enamel and dentin (P > 0.05). However, decrease in microhardness was relatively less in de-ionized water and thymol solutions while glutaraldehyde decreased microhardness the most: 63% for enamel and 53% for dentin. Conclusions: Microhardness of enamel and dentin was in an acceptable range when teeth were stored for 2 months in de-ionized water, glutaraldehyde, HBSS, NaOCl or in thymol; thus, teeth kept up to 2 months in these solutions can be used for mechanical in vitro tests. However, 12 months storage significantly decreased the microhardness of enamel and dentin.
The comparative effect of propolis in two different vehicles; mouthwash and chewing-gum on plaque accumulation and gingival inflammation
Authors: Ercan Nuray , Erdemir Ebru Olgun , Ozkan Serdar Yucel , Hendek Meltem Karsiyaka
Published: May 2015

Objective: In general, chemical plaque agents have been used in mouthwashes, gels, and dentifrices. In some situations, application of mouthwashes and dentifrices can be difficult. Therefore, different approaches for oral health-care have been needed. The aim of this study was to evaluate the effect of propolis chewing-gum compared to propolis-containing mouthwash on gingival inflammation and plaque accumulation on patients that refrained from daily oral hygiene procedures for 5 days. Materials and Methods: 10 college students with systemically healthy and very good oral hygiene and gingival health were included in this randomized, single-blind, crossover 5-day plaque regrowth with a 3-day washout period clinical study. After plaque scores were reduced to zero, participants were asked to refrain from oral hygiene procedures and allocated to either propolis mouthwash or chewing-gum group. Chewing-gum was performed after meals 3 times a day for 20 min mouthwash group was instructed to rinse mouthwash 2 times a day for 1 min. On day 5, the clinical periodontal measurements containing plaque and gingival indexes were taken from the participants. Results: The both plaque and gingival indexes of propolis mouthwash group were significantly lower than that of the propolis chewing-gum group (P = 0.005). Conclusion: It was demonstrated that the propolis mouthwash was more effective than the propolis chewing gum on the plaque inhibition and the gingival inflammation.
Effect of sodium butyrate on intestinal inflammatory response to lipopolysaccharide in broiler chickens
Authors: Jiang Yun , Zhang Weihui , Gao Feng , Zhou Guanghong
Published: May 2015

Jiang, Y., Zhang, W., Gao, F. and Zhou, G. 2015. Effect of sodium butyrate on intestinal inflammatory response to lipopolysaccharide in broiler chickens. Can. J. Anim. Sci. 95: 389–395. The aim of this study was to investigate the effect of sodium butyrate (SB) supplementation on intestinal inflammatory response to lipopolysaccharide (LPS) in broiler chickens. A total of 120 one-day-old chickens (Arbor Acres) were divided into two groups and fed a control diet (without SB) or 1.00 g SB kg−1diet. Half of the chickens fed each diet were injected intra-peritoneally with 0.5 g kg−1body weight of Escherichia coli LPS at 16, 18 and 20 d of age. The results showed that the LPS challenge decreased (P<0.05) villus height and the ratio of villus height to crypt depth (V/C ratio), increased (P<0.01) crypt depth of the duodenum. SB supplementation increased (P<0.05) villus height, crypt depth and V/C ratio of the duodenum and jejunum, except for the crypt depth of the jejunum. The LPS challenge increased (P<0.05) myeloperoxidase (MPO) activities, intercellular adhesion molecule-1 (ICAM-1) and activated nuclear factor kappa B (NF-κB) levels in mucosa of the duodenum and jejunum, while decreasing (P<0.05) insulin-like growth factor-1 (IGF-1) concentrations. The LPS challenge increased (P<0.05) the mRNA levels of interleukin-1beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) in duodenal mucosa. SB supplementation decreased (P<0.05) the MPO activities and mRNA expression of TNF-α in the duodenal mucosa, and the activated NF-κB levels in mucosa of the duodenum and jejunum. There were no significant interactions between dietary SB and LPS on the histomorphology of the small intestine and those inflammatory mediators except for MPO and ICAM-1 in duodenal mucosa (P<0.05). The results indicate that SB supplementation could improve the intestinal morphology and function of broiler chickens and partially attenuate inflammatory responses caused by LPS challenge but not involving NF-κB activation.
Effect of post-weaning residual feed intake classification on grazed grass intake and performance in pregnant beef heifers
Authors: Manafiazar G. , Basarab J. A. , Baron V. S. , McKeown L. , Doce R. R. , Swift M. , Undi M. , Wittenberg K. , Ominski K.
Published: May 2015

Manafiazar, G., Basarab, J. A., Baron, V. S., McKeown, L., Doce, R. R., Swift, M., Undi, M., Wittenberg, K. and Ominski, K. 2015. Effect of post-weaning residual feed intake classification on grazed grass intake and performance in pregnant beef heifers. Can. J. Anim. Sci. 95: 369–381. There is limited knowledge of how cattle tested for feed efficiency under drylot conditions perform when they graze on summer pasture. Residual feed intake adjusted for end of test backfat thickness (RFIfat) was determined on 171 beef crossbred heifers under drylot conditions over 2 yr using an automated system. Upon completion of the test, the 10 lowest and 10 highest RFIfat (–0.54±0.17 vs. 0.58±0.15 kg DM d−1) heifers in 2012, and the 14 lowest and 14 highest RFIfat (−0.47±0.16 vs. 0.53±0.19 kg DM d−1) heifers in 2013 were selected and placed on meadow bromegrass pasture to investigate the effect of RFIfat ranking on their grass intake and performance on the pasture. The pasture adaptation period (8 d in 2012 and 19 d in 2013) was followed by a pasture feed intake experiment during which heifers were dosed twice daily (0815 and 1415) with 500 g of C32-labeled feed pellet for 13 d (day 0 to 12) and fecal sampled twice daily (0815 and 1415) from day 8 to 12. Forage DM intake on pasture for each heifer was determined using the double alkane (C31/C32) methodology. High and low RFIfat heifers were similar in body weight (BW), backfat and rump fat thickness, and average daily gain (ADG) during the grazing trial period, except backfat thickness at the end of test period. However, low RFIfat heifers consumed 5.3% less forage when expressed as kg DM d−1 (8.20±0.08 vs. 8.66±0.09, P<0.001) and 5.1% less when expressed as a percentage of body weight (1.86±0.02 vs. 1.96±0.02% of BW, P<0.001) compared with high RFIfat heifers. RFIfat measured under drylot conditions in growing heifers was positively correlated to grazed RFIfat determined in pregnant heifers (rp=0.30, P=0.04). These results suggest that beef heifers classified as low RFIfat during the post-weaning drylot period had lower dry matter intake as heifers in their first pregnancy grazing tame pasture, with no negative impact on their body weight, back-fat thickness, and ADG compared with their high RFIfat herdmates.
The relationship between the polymorphism of the porcineCASTgene and productive traits in pigs
Authors: Urbański Paweł , Pierzchała Mariusz , Terman Arkadiusz , Kamyczek Marian , Różycki Marian , Roszczyk Agnieszka , Czarnik Urszula
Published: May 2015

Urbański, P., Pierzchała, M., Terman, A., Kamyczek, M., Różycki, M., Roszczyk, A. and Czarnik, U. 2015. The relationship between the polymorphism of the porcine CAST gene and productive traits in pigs. Can. J. Anim. Sci. 95: 361–367. The aim of the study was to characterize the polymorphism of the calpastatin gene identified with ApaLI, Hpy188I and PvuII restriction enzymes in two pig breeds and one line bred in Poland, and to evaluate the relationship between the CAST genotype and carcass traits. The analysis covered a total of 617 pigs of two breeds, Polish Landrace (185) and Polish Large White (216), and synthetic line L990 (216). All animals studied appeared to be monomorphic at two loci: CAST/ApaLI and CAST/Hpy188I, while three genotypes were observed at CAST/PvuII locus. Statistical analysis was carried out for each breed separately using the least square methods of the GLM procedure. The model included the effect of the CAST genotype, fixed effect of the RYR1 genotype and the effect of the sire. Because the RYR1 genotype could significantly modify the effect of other genes, the effect of the RYR1 genotype was included in the statistical model. The relationship between the polymorphism and several productive traits was identified in each of the study groups of pigs. Animals carrying the heterozygous genotype at this locus showed most extreme values for some of the traits tested. Our results suggest that the CAST /PvuII genotype might be utilized in the selection of valuable pig carcass traits, particularly weight and size of the loin.
Alleviation of injury from chlorimuron-ethyl in maize treated with safener 3-dichloroacetyl oxazolidine
Authors: Zhao Li-Xia , Qu Hai-Tao , Fu Ying , Gao Shuang , Ye Fei
Published: May 2015

Zhao, L.-X., Qu, H.-T., Fu, Y., Gao, S. and Ye, F. 2015. Alleviation of injury from chlorimuron-ethyl in maize treated with safener 3-dichloroacetyl oxazolidine. Can. J. Plant Sci. 95: 897–903. The protective effects of herbicide safeners, including 3-dichloroacetyl-2,2-dimethyl-1,3-oxazolidine (R-28725), 3-dichloroacetyl-2,2-dimethyl-4-ethyl-1,3-oxazolidine (Racemate), and its two enantiomers (R)-3-dichloroacetyl-2,2-dimethyl-4-ethyl-1,3-oxazolidine (R-enantiomer) and (S)-3-dichloroacetyl-2,2-dimethyl-4-ethyl-1,3-oxazolidine (S-enantiomer), on reducing the phytotoxicity of chlorimuron-ethyl to maize were investigated. Soaking the seeds in safeners increased the endogenous glutathione (GSH) content and glutathione-S-transferase (GST) activity of maize. When induced by R-enantiomer, the GST activity in vivo and in vitro increased 180 and 192% compared with control, respectively. R-28725 and R-enantiomer also increased the acetolactate synthase (ALS) activity inhibited by chlorimuron-ethyl from 45 to 100 and 97% compared with the control, respectively. The kinetic parameter Vmax of GST in the maize treated with R-28725 and R-enantiomer increased by 103 and 92%, respectively, compared with the control. Our results suggest that R-28725 and R-enantiomer could significantly improve the GSH content, GST activity, and ALS activity of maize. Overall, maize could be protected from the injury caused by chlorimuron-ethyl.
Use of biochar and oxidized lignite for reconstructing functioning agronomic topsoil: Effects on soil properties in a greenhouse study
Authors: Bekele Asfaw , Roy Julie L. , Young Michelle A.
Published: May 2015

Bekele, A., Roy, J. L. and Young, M. A. 2015. Use of biochar and oxidized lignite for reconstructing functioning agronomic topsoil: Effects on soil properties in a greenhouse study. Can. J. Soil Sci. 95: 269–285. Interest in the use of biochar as soil amendment has grown recently. However, studies evaluating its potential use for reclamation of disturbed agricultural lands are lacking. We studied the effects of amending clay, loam, and sand subsoil substrates with wood biochar pyrolized at 800°C, oxidized lignite (humalite), or labile organic mix (sawdust, wheat straw, and alfalfa; LOM) on soil organic carbon (C), microbial biomass, dry aggregated size distribution and penetration resistance in greenhouse. We also considered the co-application of LOM and biochar or humalite to the subsoil substrates as treatments where C from either biochar or humalite represented a stable form of C. The amount and composition of the mix of organic amendments was determined for each subsoil so that organic C levels of reconstructed topsoil would be equivalent to that of the corresponding native topsoil in the long term. Field pea (Pisum sativum L.) and barley (Hordeum vulgare L.) were grown in rotation in four sequential greenhouse studies. Results from soil analysis at the end of study II and study IV showed that subsoils amended with biochar or humalite had higher organic C than those with LOM only, regardless of soil type. Labile organic mix added alone or together with biochar or humalite to subsoil increased microbial biomass and decreased geometric mean diameter of the dry soil aggregates. The effects of biochar or humalite-only amendment on these soil properties were not significant relative to the unamended subsoil substrate. Simultaneous application of biochar or humalite with LOM can potentially be used for topsoil reconstruction and reclamation of disturbed agricultural lands, and to maintain soil quality in the long term. However, long-term field studies are required to ascertain the longevity of the desirable properties reported in this study and to assess effects associated with aging of biochar or humalite in the soil.
Anti-norms on Finite von Neumann Algebras
Authors: Bourin Jean-Christophe , Hiai Fumio
Published: May 2015

As the reversed version of usual symmetric norms, we introduce the notion of symmetric anti-norms

\|\cdot\|_!

defined on the positive operators affiliated with a finite von Neumann algebra with a finite normal trace. Related to symmetric anti-norms, we develop majorization theory and superadditivity inequalities of the form

\|\psi(A+B)\|_!\ge\|\psi(A)\|_!+\|\psi(B)\|_!

for a wide class of functions

\psi

.
Power Operations and Coactions in Highly Commutative Homology Theories
Authors: Baker Andrew
Published: May 2015

Power operations in the homology of infinite loop spaces, and

H_\infty

or

E_\infty

ring spectra have a long history in Algebraic Topology. In the case of ordinary mod

p

homology for a prime

p

, the power operations of Kudo, Araki, Dyer and Lashof interact with Steenrod operations via the Nishida relations, but for many purposes this leads to complicated calculations once iterated applications of these functions are required. On the other hand, the homology coaction turns out to provide tractable formulae better suited to exploiting multiplicative structure.

We show how to derive suitable formulae for the interaction between power operations and homology coactions in a wide class of examples; our approach makes crucial use of modern frameworks for spectra with well behaved smash products. In the case of mod

p

homology, our formulae extend those of Bisson and Joyal to odd primes. We also show how to exploit our results in sample calculations, and produce some apparently new formulae for the Dyer-Lashof action on the dual Steenrod algebra.
Non-local Operators, Non-Archimedean Parabolic-type Equations with Variable Coefficients and Markov Processes
Authors: Chacón-Cortes Leonardo F. , Zúñiga-Galindo W. A.
Published: May 2015

In this article, we introduce a new class of parabolic-type pseudodifferential equations with variable coefficients over the

p

-adics. We establish the existence and uniqueness of solutions for the Cauchy problem associated with these equations. The fundamental solutions of these equations are connected with Markov processes. Some of these equations are related to new models of complex systems.
Uniform Resolvent Estimates for Magnetic Schrödinger Operators in a 2D Exterior Domain and their Applications to Related Evolution Equations
Authors: Mochizuki Kiyoshi , Nakazawa Hideo
Published: May 2015

We consider the magnetic Schrödinger operator in an exterior domain

\Omega \subset \mathbb R^2

with star-shaped boundary with respect to the origin. We prove uniform resolvent estimates under suitable decay and smallness conditions on the magnetic field and external potential. The results are then used to obtain smoothing properties for the corresponding evolution equations.
Thermal transport in a 2D stressed nanostructure with mass gradient
Authors: Barreto R. , Carusela M. F. , Mancardo Viotti A. , Monastra Alejandro
Published: May 2015

Inspired by some recent molecular dynamics (MD) simulations and experiments on suspended graphene nanoribbons, we study a simplified model where the atoms are disposed in a rectangular lattice coupled by nearest neighbor interactions which are quadratic in the interatomic distance. The system has a mechanical strain, and the border atoms are coupled to Langevin thermal baths. Atom masses vary linearly in the longitudinal direction, modeling an isotope or doping distribution. This asymmetry and tension modify thermal properties. Although the atomic interaction is quadratic, the potential is anharmonic in the coordinates. By direct MD simulations and solving Fokker-Planck equations at low temperatures, we can better understand the role of anharmonicities in thermal rectification. We observe an increasing thermal current with an increasing applied mechanical tension. The temperatures and thermal currents vary along the transverse direction. This effect can be useful to establish which parts of the system are more sensitive to thermal damage. We also study thermal rectification as a function of strain and system size.Received: 20 Novembre 2014,  Accepted: 17 April 2015; Edited by: C. A. Condat, G. J. Sibona; DOI: http://dx.doi.org/10.4279/PIP.070008Cite as: R Barreto, M F Carusela, A Mancardo Viotti, A G Monastra, Papers in Physics 7, 070008 (2015)This paper, by R Barreto, M F Carusela, A Mancardo Viotti, A G Monastra, is licensed under the Creative Commons Attribution License 3.0.
Origin of springtime ozone enhancements in the lower troposphere over Beijing: in situ measurements and model analysis
Authors: Huang J. , Liu H. , Crawford J. H. , Chan C. , Considine D. B. , Zhang Y. , Zheng X. , Zhao C. , Thouret V. , Oltmans S. J. , Liu S. C. , Jones D. B. A. , Steenrod S. D. , Damon M. R.
Published: May 2015

Abstract. Ozone (O3) concentrations in the lower troposphere (LT) over Beijing have significantly increased over the past 2 decades as a result of rapid industrialization in China, with important implications for regional air quality and the photochemistry of the background troposphere. We characterize the vertical distribution of lower-tropospheric (0–6 km) O3 over Beijing using observations from 16 ozonesonde soundings during a field campaign in April–May 2005 and MOZAIC (Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft) over 13 days in the same period. We focus on the origin of LT O3 enhancements observed over Beijing, particularly in May. We use a global 3-D chemistry and transport model (GEOS-Chem CTM; GEOS – Goddard Earth Observing System) driven by assimilated meteorological fields to examine the transport pathways for O3 pollution and to quantify the sources contributing to O3 and its enhancements in the springtime LT over Beijing. Output from the Global Modeling Initiative (GMI) CTM is also used. High O3 concentrations (up to 94.7 ppbv) were frequently observed at the altitude of ~ 1.5–2 km. The CTMs captured the timing of the occurrences but significantly underestimated their magnitude. GEOS-Chem simulations and a case study showed that O3 produced in the Asian troposphere (especially from Asian anthropogenic pollution) made major contributions to the observed O3 enhancements. Contributions from anthropogenic pollution in the European and North American troposphere were reduced during these events, in contrast with days without O3 enhancements when contributions from Europe and North America were substantial. The O3 enhancements typically occurred under southerly wind and warmer conditions. It is suggested that an earlier onset of the Asian summer monsoon would cause more O3 enhancement events in the LT over the North China Plain in late spring and early summer.
Characterization of thermal structure and conditions for overshooting of tropical and extratropical cyclones with GPS radio occultation
Authors: Biondi R. , Steiner A. K. , Kirchengast G. , Rieckh T.
Published: May 2015

Abstract. The thermal structure of tropical cyclones (TCs) in different ocean basins is studied using global positioning system (GPS) radio occultation (RO) measurements co-located with TCs' best tracks. The objective of this work is to understand the mutual influence of TCs and atmospheric parameters in different regions. We selected more than 20 000 GPS RO profiles co-located with TCs in a time window of 6 h and space window of 600 km from the TC center in the period 2001–2012 and classified them by intensity of the cyclone and by ocean basin. The results show that TCs have different characteristics depending on the basin, which affects the cloud top altitude and the TC thermal structure which usually shows a negative temperature anomaly near the cloud top altitude. In the Northern Hemisphere ocean basins, the temperature anomaly becomes positive above the cloud top while in the Southern Hemisphere ocean basins it stays negative up to about 25 km in altitude. Furthermore, in the Southern Hemisphere the storms reach higher cloud top altitudes than in the Northern Hemisphere ocean basins, indicating that possible overshootings overpass the climatological tropopause more deeply at extratropical latitudes. The comparison of the TC thermal structure with the respective monthly mean tropopause altitude allows for a detailed analysis of the probability for possible overshooting. While the co-locations between GPS ROs and TC tracks are well distributed in all the ocean basins, conditions for possible overshootings are found to be more frequent in the Southern Hemisphere basins and in the northern Indian Ocean basin. However, the number of possible overshootings for high intensity storms (i.e., TC categories 1–5) is the highest in the western Pacific Ocean basin.
Ice nucleation by combustion ash particles at conditions relevant to mixed-phase clouds
Authors: Umo N. S. , Murray B. J. , Baeza-Romero M. T. , Jones J. M. , Lea-Langton A. R. , Malkin T. L. , O'Sullivan D. , Neve L. , Plane J. M. C. , Williams A.
Published: May 2015

Abstract. Ice-nucleating particles can modify cloud properties with implications for climate and the hydrological cycle; hence, it is important to understand which aerosol particle types nucleate ice and how efficiently they do so. It has been shown that aerosol particles such as natural dusts, volcanic ash, bacteria and pollen can act as ice-nucleating particles, but the ice-nucleating ability of combustion ashes has not been studied. Combustion ashes are major by-products released during the combustion of solid fuels and a significant amount of these ashes are emitted into the atmosphere either during combustion or via aerosolization of bottom ashes. Here, we show that combustion ashes (coal fly ash, wood bottom ash, domestic bottom ash, and coal bottom ash) nucleate ice in the immersion mode at conditions relevant to mixed-phase clouds. Hence, combustion ashes could play an important role in primary ice formation in mixed-phase clouds, especially in clouds that are formed near the emission source of these aerosol particles. In order to quantitatively assess the impact of combustion ashes on mixed-phase clouds, we propose that the atmospheric abundance of combustion ashes should be quantified since up to now they have mostly been classified together with mineral dust particles. Also, in reporting ice residue compositions, a distinction should be made between natural mineral dusts and combustion ashes in order to quantify the contribution of combustion ashes to atmospheric ice nucleation.
Fine-particle water and pH in the southeastern United States
Authors: Guo H. , Xu L. , Bougiatioti A. , Cerully K. M. , Capps S. L. , Hite J. R. , Carlton A. G. , Lee S.-H. , Bergin M. H. , Ng N. L. , Nenes A. , Weber R. J.
Published: May 2015

Abstract. Particle water and pH are predicted using meteorological observations (relative humidity (RH), temperature (T)), gas/particle composition, and thermodynamic modeling (ISORROPIA-II). A comprehensive uncertainty analysis is included, and the model is validated. We investigate mass concentrations of particle water and related particle pH for ambient fine-mode aerosols sampled in a relatively remote Alabama forest during the Southern Oxidant and Aerosol Study (SOAS) in summer and at various sites in the southeastern US during different seasons, as part of the Southeastern Center for Air Pollution and Epidemiology (SCAPE) study. Particle water and pH are closely linked; pH is a measure of the particle H+ aqueous concentration and depends on both the presence of ions and amount of particle liquid water. Levels of particle water, in turn, are determined through water uptake by both the ionic species and organic compounds. Thermodynamic calculations based on measured ion concentrations can predict both pH and liquid water but may be biased since contributions of organic species to liquid water are not considered. In this study, contributions of both the inorganic and organic fractions to aerosol liquid water were considered, and predictions were in good agreement with measured liquid water based on differences in ambient and dry light scattering coefficients (prediction vs. measurement: slope = 0.91, intercept = 0.5 μg m−3, R2 = 0.75). ISORROPIA-II predictions were confirmed by good agreement between predicted and measured ammonia concentrations (slope = 1.07, intercept = −0.12 μg m−3, R2 = 0.76). Based on this study, organic species on average contributed 35% to the total water, with a substantially higher contribution (50%) at night. However, not including contributions of organic water had a minor effect on pH (changes pH by 0.15 to 0.23 units), suggesting that predicted pH without consideration of organic water could be sufficient for the purposes of aqueous secondary organic aerosol (SOA) chemistry. The mean pH predicted in the Alabama forest (SOAS) was 0.94 ± 0.59 (median 0.93). pH diurnal trends followed liquid water and were driven mainly by variability in RH; during SOAS nighttime pH was near 1.5, while daytime pH was near 0.5. pH ranged from 0.5 to 2 in summer and 1 to 3 in the winter at other sites. The systematically low pH levels in the southeast may have important ramifications, such as significantly influencing acid-catalyzed reactions, gas–aerosol partitioning, and mobilization of redox metals and minerals. Particle ion balances or molar ratios, often used to infer pH, do not consider the dissociation state of individual ions or particle liquid water levels and do not correlate with particle pH.
Methodology for determining multilayered temperature inversions
Authors: Fochesatto G. J.
Published: May 2015

Abstract. Temperature sounding of the atmospheric boundary layer (ABL) and lower troposphere exhibits multilayered temperature inversions specially in high latitudes during extreme winters. These temperature inversion layers are originated based on the combined forcing of local- and large-scale synoptic meteorology. At the local scale, the thermal inversion layer forms near the surface and plays a central role in controlling the surface radiative cooling and air pollution dispersion; however, depending upon the large-scale synoptic meteorological forcing, an upper level thermal inversion can also exist topping the local ABL. In this article a numerical methodology is reported to determine thermal inversion layers present in a given temperature profile and deduce some of their thermodynamic properties. The algorithm extracts from the temperature profile the most important temperature variations defining thermal inversion layers. This is accomplished by a linear interpolation function of variable length that minimizes an error function. The algorithm functionality is demonstrated on actual radiosonde profiles to deduce the multilayered temperature inversion structure with an error fraction set independently.
Dynamic C and N stocks – key factors controlling the C gas exchange of maize in heterogenous peatland
Authors: Pohl M. , Hoffmann M. , Hagemann U. , Giebels M. , Albiac Borraz E. , Sommer M. , Augustin J.
Published: May 2015

Abstract. The drainage and cultivation of fen peatlands create complex small-scale mosaics of soils with extremely variable soil organic carbon (SOC) stocks and groundwater levels (GWLs). To date, the significance of such sites as sources or sinks for greenhouse gases such as CO2 and CH4 is still unclear, especially if the sites are used for cropland. As individual control factors such as GWL fail to account for this complexity, holistic approaches combining gas fluxes with the underlying processes are required to understand the carbon (C) gas exchange of drained fens. It can be assumed that the stocks of SOC and N located above the variable GWL – defined as dynamic C and N stocks – play a key role in the regulation of the plant- and microbially mediated CO2 fluxes in these soils and, inversely, for CH4. To test this assumption, the present study analysed the C gas exchange (gross primary production – GPP; ecosystem respiration – Reco; net ecosystem exchange – NEE; CH4) of maize using manual chambers for 4 years. The study sites were located near Paulinenaue, Germany, where we selected three soil types representing the full gradient of GWL and SOC stocks (0–1 m) of the landscape: (a) Haplic Arenosol (AR; 8 kg C m−2); (b) Mollic Gleysol (GL; 38 kg C m−2); and (c) Hemic Histosol (HS; 87 kg C m−2). Daily GWL data were used to calculate dynamic SOC (SOCdyn) and N (Ndyn) stocks. Average annual NEE differed considerably among sites, ranging from 47 ± 30 g C m−2 yr−1 in AR to −305 ± 123 g C m−2 yr−1 in GL and −127 ± 212 g C m−2 yr−1 in HS. While static SOC and N stocks showed no significant effect on C fluxes, SOCdyn and Ndyn and their interaction with GWL strongly influenced the C gas exchange, particularly NEE and the GPP : Reco ratio. Moreover, based on nonlinear regression analysis, 86% of NEE variability was explained by GWL and SOCdyn. The observed high relevance of dynamic SOC and N stocks in the aerobic zone for plant and soil gas exchange likely originates from the effects of GWL-dependent N availability on C formation and transformation processes in the plant–soil system, which promote CO2 input via GPP more than CO2 emission via Reco. The process-oriented approach of dynamic C and N stocks is a promising, potentially generalisable method for system-oriented investigations of the C gas exchange of groundwater-influenced soils and could be expanded to other nutrients and soil characteristics. However, in order to assess the climate impact of arable sites on drained peatlands, it is always necessary to consider the entire range of groundwater-influenced mineral and organic soils and their respective areal extent within the soil landscape.
Sensitivity of the air–sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short-term variability
Authors: Lansø A. S. , Bendtsen J. , Christensen J. H. , Sørensen L. L. , Chen H. , Meijer H. A. J. , Geels C.
Published: May 2015

Abstract. Minimising the uncertainties in estimates of air–sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air–sea CO2 flux along with its sensitivity to, for example, short-term temporal variability in wind speed, atmospheric mixing height and atmospheric CO2 concentration. With this study, the importance of high spatiotemporal resolution of atmospheric parameters for the air–sea CO2 flux is assessed for six sub-basins within the Baltic Sea and Danish inner waters. A new climatology of surface water partial pressure of CO2 (pCO2w) has been developed for this coastal area based on available data from monitoring stations and on-board pCO2w measuring systems. Parameterisations depending on wind speed were applied for the transfer velocity to calculate the air–sea CO2 flux. Two model simulations were conducted – one including short-term variability in atmospheric CO2 (VAT), and one where it was not included (CAT). A seasonal cycle in the air–sea CO2 flux was found for both simulations for all sub-basins with uptake of CO2 in summer and release of CO2 to the atmosphere in winter. During the simulated period 2005–2010, the average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish straits and Kattegat was 287 and 471 Gg C yr−1 for the VAT and CAT simulations, respectively. The obtained difference of 184 Gg C yr−1 was found to be significant, and thus ignoring short-term variability in atmospheric CO2 does have a sizeable effect on the air–sea CO2 exchange. The combination of the atmospheric model and the new pCO2w fields has also made it possible to make an estimate of the marine part of the Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C yr−1 was found for the Danish waters. A large uncertainty is connected to the air–sea CO2 flux in particular caused by the transfer velocity parameterisation and the applied pCO2w climatology. However, as a significant difference of 184 Gg C yr−1 is obtained between the VAT and CAT simulations, the present study underlines the importance of including short-term variability in atmospheric CO2 concentration in future model studies of the air–sea exchange in order to minimise the uncertainty.
Northern Hemisphere control of deglacial vegetation changes in the Rufiji uplands (Tanzania)
Authors: Bouimetarhan I. , Dupont L. , Kuhlmann H. , Pätzold J. , Prange M. , Schefuß E. , Zonneveld K.
Published: May 2015

Abstract. In tropical eastern Africa, vegetation distribution is largely controlled by regional hydrology, which has varied over the past 20 000 years. Therefore, accurate reconstructions of past vegetation and hydrological changes are crucial for a better understanding of climate variability in the tropical southeastern African region. We present high-resolution pollen records from a marine sediment core recovered offshore of the Rufiji River delta. Our data document significant shifts in pollen assemblages during the last deglaciation, identifying, through changes in both upland and lowland vegetation, specific responses of plant communities to atmospheric (precipitation) and coastal (coastal dynamics and sea-level changes) alterations. Specifically, arid conditions reflected by a maximum pollen representation of dry and open vegetation occurred during the Northern Hemisphere cold Heinrich event 1 (H1), suggesting that the expansion of drier upland vegetation was synchronous with cold Northern Hemisphere conditions. This arid period is followed by an interval in which forest and humid woodlands expanded, indicating a hydrologic shift towards more humid conditions. Droughts during H1 and the shift to humid conditions around 14.8 kyr BP in the uplands are consistent with latitudinal shifts of the intertropical convergence zone (ITCZ) driven by high-latitude Northern Hemisphere climatic fluctuations. Additionally, our results show that the lowland vegetation, consisting of well-developed salt marshes and mangroves in a successional pattern typical for vegetation occurring in intertidal habitats, has responded mainly to local coastal dynamics related to marine inundation frequencies and soil salinity in the Rufiji Delta as well as to the local moisture availability. Lowland vegetation shows a substantial expansion of mangrove trees after ~ 14.8 kyr BP, suggesting an increased moisture availability and river runoff in the coastal area. The results of this study highlight the decoupled climatic and environmental processes to which the vegetation in the uplands and the Rufiji Delta has responded during the last deglaciation.
Astronomical calibration of the geological timescale: closing the middle Eocene gap
Authors: Westerhold T. , Röhl U. , Frederichs T. , Bohaty S. M. , Zachos J. C.
Published: May 2015

Abstract. To explore cause and consequences in past climate reconstructions highly accuracy age models are inevitable. The highly accurate astronomical calibration of the geological time scale beyond 40 million years critically depends on the accuracy of orbital models and radio-isotopic dating techniques. Discrepancies in the age dating of sedimentary successions and the lack of suitable records spanning the middle Eocene have prevented development of a continuous astronomically calibrated geological timescale for the entire Cenozoic Era. We now solve this problem by constructing an independent astrochronological stratigraphy based on Earth's stable 405 kyr eccentricity cycle between 41 and 48 million years ago (Ma) with new data from deep-sea sedimentary sequences in the South Atlantic Ocean. This new link completes the Paleogene astronomical time scale and confirms the intercalibration of radio-isotopic and astronomical dating methods back through the Paleocene-Eocene Thermal Maximum (PETM, 55.930 Ma) and the Cretaceous/Paleogene boundary (66.022 Ma). Coupling of the Paleogene 405 kyr cyclostratigraphic frameworks across the middle Eocene further paves the way for extending the Astronomical Time Scale (ATS) into the Mesozoic.