The Consequences of the Incorporation of (Aliphatic/Cycloaliphatic) Sugar-Based Non-Drop-In Monomers into Polyamides:In-Depth Study on Representative Examples

Biomass has been recently intensively exploited to mine new compounds, which potentially might be utilized for polyamide synthesis. Sugar (waste) for example offers a variety of structures including moieties containing hydroxyl groups. A polymerization of molecules with multiple hydroxyl groups is possible; however it requires the application of sophisticated and very often exhausting synthetic methods. In many instances a more effective manner of handling this problem is reduction of functionalities and therefore preparation of bifunctional, step-growth polymerizable compounds. The preparation of bifunctional monomers from multifunctional sugar-derived diacid/diesters can be achieved through dehydration, protection of hydroxyl groups with ether or, frequently intensively researched, the acetalization of those groups. The polymerization of the first type of monomer, dehydrated sugars, results in polymers, which possess cyclic moieties built into the backbone. The second approach leads to a polymer with 4 relatively small pendant groups and the last one leads to a polymer with bulky moieties based on a dioxolane or substituted dioxolane/dioxane rings as pendant groups. The incorporation of all those moieties has major consequences and repercussions for polymer properties. The bulky structures of the cycloaliphatic fragments, which are frequently incorporated into polyamides, induce rigidity, suppress crystallinity and notably influence the interaction of polymeric chains. The additional oxygen atoms in protected and unprotected molecules, usually an inherent part of the abovementioned moieties, disrupt hydrogen bond interactions, influence the thermal properties, but also are an excellent way to introduce new functionalities into the polymer. Furthermore, since polyamides are usually synthesized via polycondensation at high temperatures, which is potentially destructive for those heterofunctional moieties, researchers frequently choose for solution polymerization methods, which are not environmentally friendly nor industrially relevant. It is however possible to perform high temperature melt polycondensation of those moieties after careful consideration of the possible consequences for those structures and by right choice of the starting material. In this chapter, a short review of many literature reports will be covered regarding sugar-based moieties and the consequences of their incorporation into polyamides will be considered. At the beginning, the synthetic approach applied for those type of polymers will be discussed from efficiency point of view. Recent advances in the melt polycondensation of cyclic, protected polyhydroxyacid derivatives will be examined and put in a broader perspective. Furthermore, the influence of those moieties on the properties of polymers therefrom (e.g., thermal stability, hydrogen bonding interaction, crystallinity of the polymer) and the influence of structural parameters in the monomers on the reactivity of the polymerizable functional groups will be discussed. The focus point is to find a global relationship between sugar-based monomer structures and properties of polyamides based on a careful analysis of existing reports for representative examples of typical sugar-based molecules

The Consequences of the Incorporation of (Aliphatic/Cycloaliphatic) Sugar-Based Non-Drop-In Monomers into Polyamides:In-Depth Study on Representative Examples

Biomass has been recently intensively exploited to mine new compounds, which potentially might be utilized for polyamide synthesis. Sugar (waste) for example offers a variety of structures including moieties containing hydroxyl groups. A polymerization of molecules with multiple hydroxyl groups is possible; however it requires the application of sophisticated and very often exhausting synthetic methods. In many instances a more effective manner of handling this problem is reduction of functionalities and therefore preparation of bifunctional, step-growth polymerizable compounds. The preparation of bifunctional monomers from multifunctional sugar-derived diacid/diesters can be achieved through dehydration, protection of hydroxyl groups with ether or, frequently intensively researched, the acetalization of those groups. The polymerization of the first type of monomer, dehydrated sugars, results in polymers, which possess cyclic moieties built into the backbone. The second approach leads to a polymer with 4 relatively small pendant groups and the last one leads to a polymer with bulky moieties based on a dioxolane or substituted dioxolane/dioxane rings as pendant groups. The incorporation of all those moieties has major consequences and repercussions for polymer properties. The bulky structures of the cycloaliphatic fragments, which are frequently incorporated into polyamides, induce rigidity, suppress crystallinity and notably influence the interaction of polymeric chains. The additional oxygen atoms in protected and unprotected molecules, usually an inherent part of the abovementioned moieties, disrupt hydrogen bond interactions, influence the thermal properties, but also are an excellent way to introduce new functionalities into the polymer. Furthermore, since polyamides are usually synthesized via polycondensation at high temperatures, which is potentially destructive for those heterofunctional moieties, researchers frequently choose for solution polymerization methods, which are not environmentally friendly nor industrially relevant. It is however possible to perform high temperature melt polycondensation of those moieties after careful consideration of the possible consequences for those structures and by right choice of the starting material. In this chapter, a short review of many literature reports will be covered regarding sugar-based moieties and the consequences of their incorporation into polyamides will be considered. At the beginning, the synthetic approach applied for those type of polymers will be discussed from efficiency point of view. Recent advances in the melt polycondensation of cyclic, protected polyhydroxyacid derivatives will be examined and put in a broader perspective. Furthermore, the influence of those moieties on the properties of polymers therefrom (e.g., thermal stability, hydrogen bonding interaction, crystallinity of the polymer) and the influence of structural parameters in the monomers on the reactivity of the polymerizable functional groups will be discussed. The focus point is to find a global relationship between sugar-based monomer structures and properties of polyamides based on a careful analysis of existing reports for representative examples of typical sugar-based molecules

Effectiveness of sorting single-walled carbon nanotubes by diameter using polyfluorene derivatives

Semiconducting single-walled carbon nanotubes (SWCNTs) sorted by conjugated polymers are of great interest for electronic and optoelectronic applications. Here we demonstrate by optical methods that the selectivity of conjugated polymers for semiconducting SWCNTs is influenced by the structure of their side-chains and/or the molecular weight of the macromolecules, and that side chain functionalities determine the solubility in different dispersion media. Moreover, high resolution time-resolved photoluminescence measurements provide evidence of energy transfer from tubes with larger band gaps compared to those with smaller band gaps coexisting in SWCNT bundles.

A prospective study: current problems in radiotherapy for nasopharyngeal carcinoma in Yogyakarta, Indonesia

Introduction Nasopharyngeal carcinoma (NPC) has a high incidence in Indonesia. Previous study in Yogyakarta revealed a complete response of 29% and a median overall survival of less than 2 years. These poor treatment outcome are influenced by the long diagnose-to-treatment interval to radiotherapy (DTI) and the extended overall treatment time of radiotherapy (OTT). This study reveals insight why the OTT and DTI are prolonged. Method All patients treated with curative intent radiotherapy for NPC between July 2011 until October 2012 were included. During radiotherapy a daily diary was kept, containing information on DTI, missed radiotherapy days, the reason for missing and length of OTT. Results Sixty-eight patients were included. The median DTI was 106 days (95% CI: 98−170). Fifty-nine patients (87%) finished the treatment. The median OTT for radiotherapy was 57 days (95% CI: 57-65). The main reason for missing days was an inoperative radiotherapy machine (36%). Other reasons were patient’s poor condition (21%), public holidays (14%), adjustment of the radiation field (7%), power blackout (3%), inoperative treatment planning system (2%) and patient related reasons (9%). Patient’s insurance type was correlated to DTI in disadvantage for poor people. Conclusion Yogyakarta has a lack of sufficient radiotherapy units which causes a delay of 3-4 months, besides the OTT is extended by 10-12 days. This influences treatment outcome to a great extend. The best solution would be creating sufficient radiotherapy units and better management in health care for poor patients. The growing economy in Indonesia will expectantly in time enable these solutions, but in the meantime solutions are needed. Solutions can consist of radiation outside office hours, better maintenance of the facilities and more effort from patient, doctor and nurse to finish treatment in time. These results are valuable when improving cancer care in low and middle income countries

Lower mortality from nasopharyngeal cancer in The Netherlands since 1970 with differential incidence trends in histopathology

SummaryObjectiveNasopharyngeal carcinoma (NPC) is rare in western countries albeit affected by common and unrelated phenomena: smoking less in men, more in women and immigration from China and North Africa. We studied trends in NPC incidence, tumour morphology, survival and mortality in order to assess progress against this cancer.Materials and methodsA trend analysis was performed with nationwide incidence and survival data (from The Netherlands Cancer registry in 1989–2009), followed by analysis of mortality (data from Statistics Netherlands) covering the period 1970–2009, and calculating estimated percentages of change (EAPC) in both. According to the WHO classification we distinguished keratinizing SCC (WHO-I), differentiated (WHO-IIA) and undifferentiated (WHO-IIB) non-keratinizing carcinoma.ResultsNPC incidence significantly decreased since 1989, especially in males (EAPC 1989–2009: −1.3; 95% CI: −2.5, −0.2) and in patients with keratinizing SCC (WHO-I) (EAPC: −3.6; 95% CI: −5.3, −1.8). By contrast, the incidence of differentiated non-keratinizing tumours (WHO-IIA) significantly increased in the same period (EAPC: 9.6; 95% CI: 5.6, 13.5). One- and three-year relative survival, as an indicator of disease-specific survival increased slightly from 79% to 81% and from 57% to 65% since 1989. NPC mortality significantly decreased since 1970 (EAPC: −1.2; 95% CI: −1.8, −0.5) and more pronounced since 1989 (EAPC: −3.0; 95% CI: −4.3, −1.6).ConclusionDuring the past two decades, the incidence of NPC in The Netherlands decreased mainly by less keratinizing, supposedly smoking-related NPC (WHO-I). However, the incidence of non-keratinizing NPC (WHO-IIA, B) increased, most likely due to EBV infection and thus related to higher immigration levels of people from high-incidence areas

Epstein-Barr virus-targeted therapy in nasopharyngeal carcinoma

Purpose Despite successful primary treatment of nasopharyngeal carcinoma (NPC), the incidence of distant metastasis remains 25-34 %. Treatment options are limited, and survival is poor. Intratumoural Epstein-Barr virus (EBV) was used as treatment target. In NPC, EBV is present in a latent state, expressing only few non-immunogenic viral products. Gemcitabine and valproic acid can trigger EBV to the lytic state, wherein viral kinases are expressed, making EBV-positive tumour cells susceptible for antiviral therapy with, i.e. valganciclovir, and inducing an EBV-specific immune response. Methods This drug combination was applied in eight patients with EBV-positive NPC, refractory to conventional treatment. The primary endpoints were safety, tolerability and clinical response. Secondary endpoint was to get proof of concept based on biomarkers, i.e. pharmacokinetics, EBV-DNA load in whole blood and nasopharyngeal brushes, EBV-RNA profiling for proof of lytic induction, EBV-IgG and EBV-IgA levels and diversity and EBV-specific T cell response. Results The best observed clinical response was partial in two patients (25 %) and stable disease in three patients (37.5 %). The median survival was 9 months (95 % confidence interval 7-17 months). Effective dose levels were reached. Peaking of EBV-DNA loads in blood and brush proved the biological effect on EBV during most treatment cycles. In one patient, RNA profiling confirmed lytic EBV induction. EBV-IgG and EBV-IgA antibody levels were already high before treatment and did not change during treatment. No changes in EBV-specific T cell response were detected. Conclusion The treatment was safe with manageable side effects, clinical response was observed, and viral activation corroborated

Temoporfin mediated photodynamic therapy in patients with local persistent and recurrent nasopharyngeal carcinoma after curative radiotherapy: A feasibility study

Background: The treatment of persistent and recurrent nasopharyngeal carcinoma (NPC) remains a challenge, especially in Indonesia. We investigated the safety and efficacy of temoporfin mediated photodynamic therapy (PDT) for patients with local persistent and recurrent NPC. Material and methods: Twenty-two patients with persistent and recurrent NPC (maximum tumor depth <10 mm) underwent PDT under local anesthesia with use of a nasopharyngeal light applicator. Three different drug doses and light intervals have been administered: treatment arm A: 0.15 mg/kg Foscan (R); 96 h drug-light interval; B: drug dose of 0.10 mg/, 48 h drug-light interval; C: drug dose of 0.075 mg/kg, 24 h drug-light interval. Toxicity was measured by using the CTCAE 3.1 scale. Results: Arm A consisted of eight patients, arms B and C consisted of seven patients. The treatment procedure was well tolerable under local anesthesia. The most common grade III toxicities for all groups is headache (n=7; 33%). No grade IV toxicity was seen. One patient died 2 days after treatment due to a misdiagnosed pneumonia. In 17 of the 22 patients a biopsy was performed after 40 weeks and showed no tumor in all biopsies. Arm A seems, in addition to comparable toxicity, clinically more ef Conclusion: The present study demonstrated that temoporfin mediated photodynamic therapy is a relatively simple technique that can be utilized to treat residual or recurrent nasopharyngeal cancer, restricted locally to the nasopharynx. (C) 2012 Elsevier B.V. All rights reserved