54 research outputs found
ESR, raman and conductivity studies on fractionated poly(2-methoxyaniline-5-sulfonic acid)
Synthesis methods used to produce poly(2-methoxyaniline-5-sulfonic acid) (PMAS), a water soluble, self-doped conducting polymer, have been shown to form two distinctly different polymer fractions with molecular weights of approximately 2 kDa and 8 -10 kDa. The low molecular weight (LMWT) PMAS fraction is redox inactive and non-conducting while the high molecular weight (HMWT) PMAS is electro-active with electrical conductivities of 0.94 0.05 S cm-1. Previous investigations have illustrated the different photochemical and electrochemical properties of these fractions, but have not correlated these properties with the structural and electronic interactions that drive them. Incomplete purification of the PMAS mixture, typically via bag dialysis, has been shown to result in a mixture of approximately 50:50 HMWT:LMWT PMAS with electrical conductivity significantly lower at approximately 0.10 to 0.26 S cm-1. The difference between the electrical conductivities of these fractions has been investigated by the controlled addition of the non-conducting LMWT PMAS fraction into the HMWT PMAS composite film with the subsequent electronic properties investigated by solid-state ESR and Raman spectroscopies. These studies illustrate strong electronic intereactions of the insulating LMWT PMAS with the emeraldine salt HMWT PMAS to substantially alter the population of the electronic charge carriers in the conducting polymer. ESR studies on these mixtures, when compared to HMWT PMAS, exhibited a lower level of electron spin in the presence of LMWT PMAS indicative of the the formation of low spin bipolarons without a change the oxidation state of the conducting HMWT fraction
Impact of COVID-19 on 1-year survival outcomes in hepatocellular carcinoma: a multicenter cohort study
INTRODUCTION: The COVID-19 pandemic has caused severe disruption of healthcare services worldwide and interrupted patients' access to essential services. During the first lockdown, many healthcare services were shut to all but emergencies. In this study, we aimed to determine the immediate and long-term indirect impact of COVID-19 health services utilisation on hepatocellular cancer (HCC) outcomes. METHODS: A prospective cohort study was conducted from 1 March 2020 until 30 June 2020, correlating to the first wave of the COVID-19 pandemic. Patients were enrolled from tertiary hospitals in the UK and Germany with dedicated HCC management services. All patients with current or past HCC who were discussed at a multidisciplinary meeting (MDM) were identified. Any delay to treatment (DTT) and the effect on survival at one year were reported. RESULTS: The median time to receipt of therapy following MDM discussion was 49 days. Patients with Barcelona Clinic Liver Cancer (BCLC) stages-A/B disease were more likely to experience DTT. Significant delays across all treatments for HCC were observed, but delay was most marked for those undergoing curative therapies. Even though severe delays were observed in curative HCC treatments, this did not translate into reduced survival in patients. CONCLUSION: Interruption of routine healthcare services because of the COVID-19 pandemic caused severe delays in HCC treatment. However, DTT did not translate to reduced survival. Longer follow is important given the delay in therapy in those receiving curative therapy
Hospital mortality among major trauma victims admitted on weekends and evenings: a cohort study
Article deposited according to publisher policy posted on SHERPA/RoMEO, 14/09/2010.YesFunding provided by the Open Access Authors Fund
A spontaneous ad hoc network to share www access
In this paper, we propose a secure spontaneous ad-hoc network, based on direct peer-to-peer interaction, to grant a quick, easy, and secure access to the users to surf the Web. The paper shows the description of our proposal, the procedure of the nodes involved in the system, the security algorithms implemented, and the designed messages. We have taken into account the security and its performance. Although some people have defined and described the main features of spontaneous ad-hoc networks, nobody has published any design and simulation until today. Spontaneous networking will enable a more natural form of wireless computing when people physically meet in the real world. We also validate the success of our proposal through several simulations and comparisons with a regular architecture, taking into account the optimization of the resources of the devices. Finally, we compare our proposal with other caching techniques published in the related literature. The proposal has been developed with the main objective of improving the communication and integration between different study centers of low-resource communities. That is, it lets communicate spontaneous networks, which are working collaboratively and which have been created on different physical places.Authors want to give thanks to the anonymous reviewers for their valuable suggestions, useful comments, and proofreading of this paper. This work was partially supported by the Ministerio de Educacion y Ciencia, Spain, under Grant no. TIN2008-06441-C02-01, and by the "Ayudas complementarias para proyectos de I+D para grupos de calidad de la Generalitat Valenciana" (ACOMP/2010/005).Lacuesta Gilaberte, R.; Lloret, J.; GarcÃa Pineda, M.; Peñalver Herrero, ML. (2010). A spontaneous ad hoc network to share www access. EURASIP Journal on Wireless Communications and Networking. 2010:1-16. https://doi.org/10.1155/2010/232083S1162010Preuß S, Cap CH: Overview of spontaneous networking-evolving concepts and technologies. In Rostocker Informatik-Berichte. Volume 24. Fachbereich Informatik der Universit at Rostock; 2000:113-123.Gallo S, Galluccio L, Morabito G, Palazzo S: Rapid and energy efficient neighbor discovery for spontaneous networks. Proceedings of the 7th ACM International Symposium on Modeling, Analysis and Simulation of Wireless and Mobile Systems, October 2004, Venice, ItalyLatvakoski J, Pakkala D, Pääkkönen P: A communication architecture for spontaneous systems. IEEE Wireless Communications 2004, 11(3):36-42. 10.1109/MWC.2004.1308947Zarate Silva VH, De Cruz Salgado EI, Quintana FR: AWISPA: an awareness framework for collaborative spontaneous networks. Proceedings of the 36th ASEE/IEEE Frontiers in Education Conference (FIE '06), October 2006 1-6.Feeney LM, Ahlgren B, Westerlund A: Spontaneous networking: an application-oriented approach to ad hoc networking. IEEE Communications Magazine 2001, 39(6):176-181. 10.1109/35.925687Perkins CE, Bhagwat P: Highly dynamic destination-sequenced distance-vector routing (DSDV) for mobile computers. Proceedings of the Conference on Communications Architectures, Protocols and Applications (SIGCOMM '94), August 1994 234-244.Johnson DB, Maltz DA, Broch J: DSR: The Dynamic Source Routing Protocol for Multihop Wireless Ad Hoc Networks, Ad Hoc Networking. Addison-Wesley Longman Publishing, Boston, Mass, USA; 2001.Perkins C, Belding-Royer E, Das S: Ad hoc on-demand distance vector (AODV) routing. RFC 3561, July 2003Park V, Corson MS: IETF MANET Internet Draft "draft-ietf-MANET-tora-spe03.txt". Novemmer 2000.Viana AC, De Amorim MD, Fdida S, de Rezende JF: Self-organization in spontaneous networks: the approach of DHT-based routing protocols. Ad Hoc Networks 2005, 3(5):589-606.Gilaberte RL, Herrero LP: IP addresses configuration in spontaneous networks. Proceedings of the 9th WSEAS International Conference on Computers, July 2005, Athens, GreeceViana AC, Dias de Amorim M, Fdida S, de Rezende JF: Self-organization in spontaneous networks: the approach of DHT-based routing protocols. Ad Hoc Networks 2005, 3(5):589-606.Alvarez-Hamelin JI, Carneiro Viana A, Dias De Amorim M: Architectural considerations for a self-configuring routing scheme for spontaneous networks.,Tech. Rep. 1 October 2005.Lacuesta R, Peñalver L: Automatic configuration of ad-hoc networks: establishing unique IP link-local addresses. Proceedings of the International Conference on Emerging Security Information, Systems and Technologies (SECURWARE '07), October 2007, Valencia, SpainFoulks EF: Social network therapies and society: an overview. Contemporary Family Therapy 1985, 3(4):316-320.Wang Y, Wu H: DFT-MSN: the delay/fault-tolerant mobile sensor network for pervasive information gathering. Proceedings of the 25th IEEE International Conference on Computer Communications (INFOCOM '06), April 2006Kindberg T, Zhang K: Validating and securing spontaneous associations between wireless devices. In Proceedings of the 6th Information Security Conference (ISC '03), 2003. Springer; 44-53.Al-Jaroodi J: Routing security in open/dynamic mobile ad hoc networks. The International Arab Journal of Information Technology 2007, 4(1):17-25.Stajano F, Anderson RJ: The resurrecting duckling: security issues for ad-hoc wireless networks. Proceedings of the 7th International Workshop on Security Protocols, April 1999 172-194.Zhou L, Haas ZJ: Securing ad hoc networks. IEEE Network 1999, 13(6):24-30. 10.1109/65.806983Hauspie M, Simplot-Ryl I: Cooperation in ad hoc networks: enhancing the virtual currency based models. Proceedings of the 1st International Conference on Integrated Internet Ad Hoc and Sensor Networks (InterSense '06), May 2006, Nice, FranceWang X, Dai F, Qian L, Dong H: A way to solve the threat of selfish and malicious nodes for ad hoc networks. Proceedings of the International Symposium on Information Science and Engieering (ISISE '08), December 2008, Shanghai, China 1: 368-370.Kargl F, Klenk A, Weber M, Schlott S: Sensors for detection of misbehaving nodes in MANETs. Detection of Intrusion and Malware and Vulnerability Assessment (DIMVA '04), July 2004, Dortmund, Germany 83-97.Kargl F, Geiss A, Scholott S, Weber M: Secure dynamic source routing. Proceedings of the 38th Annual Hawaii International Conference on System Sciences (HICSS '05), January 2005, Big Island, Hawaii, USAGokhale S, Dasgupta P: Distributed authentication for peer-to-peer networks. Proceedings of the Symposium on Applications and the Internet Workshops, January 2003 347-353.Capkun S, Buttyán L, Hubaux J-P: Self-organized public-key management for mobile ad hoc networks. IEEE Transactions on Mobile Computing 2003, 2(1):52-64. 10.1109/TMC.2003.1195151Stajano F, Anderson R: The resurrecting duckling security issues for ad-hoc wireless networks. In Proceedings of the 7th International Workshop on Security Protocols, 1999, Berlin, Germany, Lecture Notes in Computer Science. Volume 1796. Springer; 172-194.Balfanz D, Smetters DK, Stewart P, Wong HC: Talking to strangers: authentication in ad-hoc wireless networks. Proceedings of the International Symposium on Network and Distributed Systems Security (NDSS '02), February 2002, San Diego, Calif, USABarbara D, Imielinski T: Sleepers and workaholics: caching strategies in mobile environments. Proceedings of the ACM SIGMOD International Conference on Management of Data, May 1994 1-12.Cao G: A scalable low-latency cache invalidation strategy for mobile environments. IEEE Transactions on Knowledge and Data Engineering 2003, 15(5):1251-1265. 10.1109/TKDE.2003.1232276Hu Q, Lee D: Cache algorithms based on adaptive invalidation reports for mobile environments. Cluster Computing 1998, 1(1):39-50. 10.1023/A:1019012927328Jing J, Elmagarmid A, Helal A, Alonso R: Bit-sequences: an adaptive cache invalidation method in mobile client/server environments. Mobile Networks and Applications 1997, 2(2):115-127. 10.1023/A:1013616213333Kahol A, Khurana S, Gupta S, Srimani P: An efficient cache management scheme for mobile environment. Proceedings of the 20th International Conference on Distributied Computing System (ICDCS '00), April 2000, Taipei, Taiwan 530-537.Kazar M: Synchronization and caching issues in the Andrew file system. Proceedings of USENIX Conference, February 1988, Dallas, Tex, USA 27-36.Roussopoulos M, Baker M: CUP: controlled update propagation in peer-to-peer networks. Proceedings of USENIX Annual Technical Conference, June 2003, San Antonio, Tex, USASandberg S, Kleiman S, Goldberg D, Walsh D, Lyon B: Design and implementation of the sun network file system. Proceedings of USENIX Summer Conference, June 1985, Portland, Ore, USA 119-130.Wu K, Yu PS, Chen M: Energy-efficient caching for wireless mobile computing. Proceedings of the 12th IEEE International Conference on Data Engineering, February-March 1996, New Orleans, La, USA 336-343.Yeung MKH, Kwok Y-K: Wireless cache invalidation schemes with link adaptation and downlink traffic. IEEE Transactions on Mobile Computing 2005, 4(1):68-83.Wessels D, Claffy K: Internet cache protocol (IC) v.2. http://www.ietf.org/rfc/rfc2186.txtFan L, Cao P, Almeida J, Broder AZ: Summary cache: a scalable wide-area web cache sharing protocol. IEEE/ACM Transactions on Networking 2000, 8(3):281-293. 10.1109/90.851975Dykes SG, Robbins KA: A viability analysis of cooperative proxy caching. Proceedings of the 20th Annual Joint Conference of the IEEE Computer and Communications Societies (INFOCOM '01), April 2001, Anchorage, Alaska, USA 3: 1205-1214.Wessels D, Claffy K: RFC 2186: Internet cache protocol (ICP), version 2. The Internet Engineering Taskforce, September 1997Wessels D, Claffy K: RFC 2187: application of internet cache protocol (ICP), version 2. The Internet Engineering Taskforce, September 1997Ren Q, Dunhan MH: Using semantic caching to manage location dependent data in mobile computing. Proceedings of the 6th Annual International Conference on Mobile Computing and Networking, August 2000, Boston, Mass, USA 210-221.Lim S, Lee W-C, Cao G, Das CR: Cache invalidation strategies for internet-based mobile ad hoc networks. Computer Communications 2007, 30(8):1854-1869. 10.1016/j.comcom.2007.02.020Park B-N, Lee W, Lee C: QoS-aware internet access schemes for wireless mobile ad hoc networks. Computer Communications 2007, 30(2):369-384. 10.1016/j.comcom.2006.09.004Hara T: Effective replica allocation in ad hoc networks for improving data accessibility. Proceedings of the 20th Annual Joint Conference of the IEEE Computer and Communications Societies (INFOCOM '01), April 2001, Anchorage, Alaska, USA 1568-1576.Papadopouli M, Schulzrinne H: Effects of power conservation, wireless converage and cooperation on data dissemination among mobile devices. Proceedings of the ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc '01), October 2001, Long Beach, Calif, USA 117-127.Can P, Irani S: Cost-aware WWW proxy caching algorithms. Proceedings of the USENIX Symposium on lnternet Technology and Systems, December 1997Rizzo L, Vicisano L: Replacement policies for a proxy cache. IEEE/ACM Transactions on Networking 2000, 8(2):158-170. 10.1109/90.842139Williams S, Abrams M, Strandridge CR, Abdulla G, Fox EA: Removal policies in network caches for world-wide web documents. Proceedings of the ACM SIGCOMM Conference on Applications, Technologies, Architectures, and Protocols for Computer Communications, August 1996, Palo Alto, Calif, USA 293-305.Hara T: Replica allocation in ad hoc networks with period data update. Proceedings of the 3rd International Conference on Mobile Data Management (MDM '02), July 2002, Edmonton, Canada 79-86.Papadopouli M, Schulzrinne H: Effects of power conservation, wireless coverage and cooperation on data dissemination among mobile devices. Proceedings of the ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc '01), October 2001, Long Beach, Calif, USA 117-127.Sailhan F, Issarny V: Cooperative caching in ad hoc networks. Proceedings of the 4th International Conference on Mobile Data Management (MDM '03), January 2003, Melbourne, Australia, Lecture Notes in Computer Science 2574: 13-28.Yin L, Cao G: Supporting cooperative caching in ad hoc networks. IEEE Transactions on Mobile Computing 2006, 5(1):77-89.Karumanchi G, Muralidharan S, Prakash R: Information dissemination in partitionable mobile ad hoc networks. Proceedings of the 18th IEEE Symposium on Reliable Distributed Systems (SRDS '99), October 1999, Lausanne, Switzerland 4-13.Corson MS, Macker JP, Cirincione GH: Internet-based mobile ad hoc networking. IEEE Internet Computing 1999, 3(4):63-70. 10.1109/4236.780962Lim S, Lee W-C, Cao G, Das CR: A novel caching scheme for improving internet-based mobile ad hoc networks performance. Ad Hoc Networks 2006, 4(2):225-239. 10.1016/j.adhoc.2004.04.013Opnet Modeler http://www.opnet.com/solutions/network_rd/modeler_wireless.htmlLacuesta R, Lloret J, Garcia M, Peñalver L: Two secure and energy-saving spontaneous ad-hoc protocol for wireless mesh client networks. Journal of Network and Computer Applications. In pres
On metallic characteristics in some conducting polymers
Polyaniline (PANI) exhibits a dc conductivity σ ≈ 10−1 S/cm when it is doped with poly(styrenesulfonic acid) (PSSA) such that the number of sulfonate groups per two-ring PANI unit (y) is 2. On increasing the dopant amount to y = 12, σ drops to 10−5 S/cm. The EPR-derived magnetic susceptibility of these two conducting polymers gives nearly the same density of states at the Fermi level N(EF) ≈ 0.65 ± 0.05 states/eV 2-rings. The corresponding electronic specific heat coefficient as calculated from this N(EF) value does not appear to be inconsistent with the results from low temperature calorimetric measurements. Similarly, with y′ defined as the number of sulfonate groups per three-ring PEDOT unit, PSSA-doping of poly(ethylenedioxythiophene) (PEDOT) yields different σ ≈ 10−1 and 10−5 S/cm at y′ = 5.7 and 45.9, respectively, but the same N(EF) ≈ 0.55 ± 0.05 states/eV 3-rings. These observations suggest that the additional dopants, which help with dispersion in processing conducting polymers, do not alter the metallic domains but are located in the disordered regions surrounding them. The N(EF) values also remain practically the same between p-toluenesulfonic acid (PTSA) doped PANI and its dispersed blend in poly(methylmethacrylate) (PMMA), as well as for PEDOT–PTSA before and after its being subjected to an additional dispersion step
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