Mortality after kidney transplantation: 10-year outcomes.

OBJECTIVES: In the past decade, advances in immunological therapy have increased the survival of kidney recipients and their grafts. However, it has not achieved the desired level of improvement. This study aims to reveal the mortality among kidney recipients. METHODS: Medical data of the patients, who had undergone kidney transplantation (KT) between November 2010 and December 2020, were retrospectively reviewed. Inclusion criteria were adult kidney recipients, who had died. Exclusion criteria were pediatric recipients, recipients of en bloc and dual KT, recipients with missing data, and recipients with a primary non-functioning graft. The recipients were grouped according to their donor type; Group 1 (from a living donor) and Group 2 (from a deceased donor). Subgroup analyses were done for mortality by time-period post-transplant and for infectious causes of mortality. RESULTS: Of 314 recipients, 35 (11.14%) died. Twenty-nine recipients were included in the study (Group 1: 17 and Group 2: 12). The most common cause of mortality was infection (58.6%), and the second was cardiovascular disease (CVD) (24.1%). Sepsis developed in 29.4% of infection-related deaths, while COVID-19 constituted 23.5% of infection-related deaths. CONCLUSION: Early diagnosis and treatment of infectious and CVD are important to improve survival in kidney recipients.

OBJETIVOS: En la última década, los avances en la terapia inmunológica han aumentado la supervivencia de los receptores de riñón y sus injertos. Sin embargo, no se pudo lograr el nivel de mejora deseado. Este estudio tiene como objetivo revelar la mortalidad entre los receptores de riñón. MATERIALES Y MÉTODOS: Se revisaron retrospectivamente los datos médicos de los pacientes, que se habían sometido a un trasplante de riñón entre Noviembre de 2010 y Diciembre de 2020. Los criterios de inclusión fueron los receptores de riñón adultos, que habían fallecido. Los criterios de exclusión fueron los receptores pediátricos, los receptores de trasplantes de riñón dual y en bloque, los receptores con datos faltantes y los receptores con un injerto primario no funcionante. Los receptores se agruparon según su tipo de donante; Grupo 1 (de un donante vivo) y Grupo 2 (de un donante fallecido). Se realizaron análisis de subgrupos para la mortalidad por período de tiempo posterior al trasplante y para las causas infecciosas de mortalidad. RESULTADOS: De 314 beneficiarios, 35 (11,14%) fallecieron. Se incluyeron 29 receptores en el estudio (Grupo 1:17; Grupo 2:12). La causa más común de mortalidad fue la infección (58,6%) y la segunda fue la enfermedad cardiovascular (24,1%). La sepsis se desarrolló en el 29,4% de las muertes relacionadas con la infección, mientras que el COVID-19 constituyó el 23,5% de las muertes relacionadas con la infección. CONCLUSIÓN: El diagnóstico y tratamiento tempranos de enfermedades infecciosas y cardiovasculares es importante para mejorar la supervivencia de los receptores de riñón.

Is there any link between atrial arrhythmias and inflammatory bowel disease?

BACKGROUND: Inflammation plays an important role in the development of cardiovascular disease, including atherosclerosis and arrhythmia. The aim of this study was to evaluate atrial conduction times (ACTs) in patients with inflammatory bowel disease (IBD) in which systemic chronic inflammation is evident. METHODS: In this cross-sectional, prospective, single-center study, 79 IBD patients (51 ulcerative colitis; 28 Crohn's disease) and 70 healthy controls were included. Atrial electromechanical properties were measured by recording simultaneous surface electrocardiography (ECG) with transthoracic echocardiography (ECHO) and tissue Doppler imaging methods. The relationship between age, disease duration, and ACT was evaluated. RESULTS: There were significantly increased conduction durations of lateral-PA (time interval from the onset of the P-wave on surface ECG to the beginning of the late diastolic wave), septal-PA, tricuspid-PA, and interatrial-electromechanical delay (IA-EMD), right intraatrial EMD, and left intraatrial (LI-EMD) durations in IBD patients (P < 0.001). In IBD patients, there was a positive correlation with age, lateral PA, septal PA, tricuspid PA, IA-EMD, and LI-EMD (P < 0.05). A positive correlation was found between disease duration and only lateral PA and tricuspid PA (P < 0.05). CONCLUSION: In IBD patients, prolonged ACT consists a potential risk for severe atrial arrhythmias. ECG and ECHO screening can be useful in identifying risk groups in IBD patients and taking precautions for future cardiac complications.

Preliminary examination of the relations between disease stage, illness perceptions, coping strategies, and psychological morbidity in chronic hepatitis B and C guided by the Common-Sense Model of Illness.

BACKGROUND AND AIMS: Chronic viral hepatitis (CVH) has a spectrum from asymptomatic disease to cirrhosis and hepatocellular carcinoma. In our study, we aimed to establish the relations between disease stage, illness perception, coping strategies and psychological morbidity in CVH. METHODS: A total of 182 patients with chronic hepatitis B (CHB) (n = 136) and chronic hepatitis C (CHC) (n = 46) were enrolled. Illness perceptions were measured with the Brief Illness Perceptions Questionnaire. Coping strategies were measured with the Carver Brief Coping Questionnaire. Anxiety and depression were measured with the Hospital Anxiety and Depression Scale. Relations were evaluated by structural equation modeling (SEM). RESULTS: In CHB, combining the questionnaire data using SEM resulted in a final model with an excellent fit [χ2 (2) = 0.00, P = 1.000, χ2/N = 0.00, root mean square error of approximation (RMSEA) < 0.001, comparative fit index (CFI) = 1.000, goodness-of-fit index (GFI) = 1.000]. Disease stage had a significant direct influence on illness perceptions (ß = 0.23, P = 0.006). Illness perceptions had a significant direct influence on emotional coping strategy, depression and anxiety (ß = 0.20, P = 0.019; ß = 0.33, P < 0.001; ß = 0.59, P < 0.001, respectively). While the use of emotional coping strategies was associated significantly (P = 0.01) with the presence of anxiety, problem-focused coping strategy was associated with depression (P = 0.004). In CHC, SEM resulted in a final model with an excellent fit [χ2 (2) = 0.078, P = 0.962, χ2/N = 0.039, RMSEA<0.001, CFI = 1.000, GFI = 0.999]. Disease stage did not have a significant direct influence on illness perceptions (P > 0.05). Illness perceptions had a significant direct influence on depression and anxiety (ß = 0.27, P = 0.023; ß = 0.44, P < 0.001, respectively). CONCLUSION: The psychological consequences of the disease vary depending on the person's perception of illness and coping strategies.

Evaluation of epicardial adipose tissue and carotid intima-media thickness as a marker of atherosclerosis in patients with inflammatory bowel disease.

BACKGROUND AND AIM: this study aimed to compare carotid intima media (CIMT) and epicardial adipose tissue (EAT) measurements, which are considered as markers for the detection of early atherosclerosis in healthy controls and inflammatory bowel disease (IBD) cases. METHODS: a total of 60 IBD patients (25 Crohn's disease and 35 ulcerative colitis) and 60 healthy patients (as a control group) were included in the study. The measurements of CIMT and EAT were performed using echocardiography and ultrasonography, respectively. Statistical analysis was used to determine the relationship between the parameters. RESULTS: the thickness of bilateral (right and left) CIMT and EAT were significantly higher in IBD than in the control group (p < 0.05). There was a positive correlation between EAT and bilateral (right and left) CIMT in IBD patients (p < 0.05). CONCLUSION: IBD is associated with an increased thickness of EAT and CIMT. Chronic inflammation in IBD may increase the risk of atherosclerotic heart disease. Thus, only measuring the thickness of EAT and CIMT can be used as an objective, easy, simple, affordable, non-invasive and accessible assessment method in order to screen for this risk.

Social stigmatization in Turkish patients with chronic hepatitis B and C.

BACKGROUND AND AIM: Viral hepatitis is the most important cause of chronic hepatitis worldwide. Stigmatization is defined as a feeling of rejection and isolation of patients by society due to illness. There are no studies on chronic viral hepatitis in the literature in English, which has its own religious and socio-cultural structure. In our study, we aimed to investigate the presence of social stigmatism and psychosocial effects on patients with different stages of chronic viral hepatitis B and C. METHODS: Forty-five patients with chronic hepatitis C and 114 patients with chronic hepatitis B were enrolled in the study. Berger's scale was used for stigmatization, composed of 40 four-point Likert items that have four subscales: personalized stigma, disclosure, negative self-image, and public attitude. Stigma score ranges between one and four. Stigma is accepted as present if the overall score is above two. RESULTS: Overall the mean stigma scores were 1.97±0.58 and 2.14±0.57 for chronic hepatitis B and C, respectively. There was stigma in 47.4% of the patients with chronic hepatitis B, and 60% of the patients with chronic hepatitis C. Being male was the risk factor on overall stigma, disclosure and public attitude in chronic hepatitis C. Living in an urban setting was the risk factor on negative self-image in chronic hepatitis C and on personalized stigma and disclosure in chronic hepatitis B. CONCLUSIONS: To the best of our knowledge, this is the first study that provides qualitative information about chronic hepatitis-related stigma. Stigmatization is a major problem in Turkey and worldwide. We believe that increasing the knowledge of the patients and society by teaching about the transmission routes of the disease and focusing on vaccination studies will prevent stigmatization.

Epidemiologic features of inflammatory bowel disease in Western Blacksea region of Turkey for the last 10 years: retrospective cohort study.

BACKGROUND/AIMS: There are only a few epidemiological study about inflammatory bowel disease in the last 10 years in Turkey, especially in Western Blacksea region. In our study, we aimed to identify the changes in the incidence and the prevalence of inflammatory bowel disease in Western Blacksea region at the last 10 years. METHODS: Totally 223 patients with inf lammatory bowel disease (160 ulcerative colitis, 63 Crohn's disease) were enrolled in the study followed up between 2004 to 2013 years. The epidemiological characteristics of patients were recorded. RESULTS: The prevalences were 12.53/105 and 31.83/105 for Crohn's disease and ulcerative colitis respectively. Mean annual incidences increased from 0.99/105 and 0.45/105 for ulcerative colitis and Crohn's disease (2004 to 2005 years) to 4.87/105 and 2.09/105 for ulcerative colitis and Crohn's disease respectively (2011 to 2013 years). While the prevalence was higher in urban areas in Crohn's disease (12.60/105 ), it was higher in rural areas in ulcerative colitis (36.17/105 ). In ulcerative colitis, mean annual incidences were 2.91/105 and 2.86/105 for urban and rural areas respectively. In Crohn's disease, they were 1.37/105 and 1.08/105 for urban and rural areas respectively. CONCLUSION: The incidence of inflammatory bowel disease seems to increase in Western Blacksea region at the last 10 years. This increment is more prevalent in rural areas.

Preparation, characterization and dynamical mechanical properties of dextran-coated iron oxide nanoparticles (DIONPs).

Dextran-coated iron oxide nanoparticles (DIONPs) with appropriate surface chemistry exhibit many interesting properties that can be exploited in a variety of biomedical applications such as magnetic resonance imaging (MRI) contrast enhancement, tissue repair, hyperthermia, drug delivery and in cell separation. This paper reports the experimental detail for preparation, characterization and investigation of thermal and dynamical mechanical characteristics of the dextran-coated Fe3O4 magnetic nanoparticles. In our work, DIONPs were prepared in a 1:2 ratio of Fe(II) and Fe(III) salt in the HCl solution with NaOH at given temperature. The obtained dextran-coated iron-oxide nanoparticles structure-property correlation was characterized by spectroscopic methods; attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and XRD. Coating dextran on the iron-oxide proof of important peaks can be seen from the ATR-FTIR. Dramatic crystallinity increment can be observed from the XRD pattern of the iron-oxide dextran nanoparticles. The thermal analysis was examined by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). Dynamical mechanical properties of dextran nanoparticles were analysed by dynamic mechanical analysis (DMA). Thermal stability of the iron oxide dextran nanoparticles is higher than that of the dextran.

Antitumor activities on HL-60 human leukemia cell line, molecular docking, and quantum-chemical calculations of some sulfonamide-benzoxazoles.

We previously synthesized some novel benzoxazole derivatives-containing sulfonamide. In this study, the compounds were investigated for their antitumor activities against the HL-60 human leukemia cells, using the MTT assay. Moreover, quantum chemical calculations using the DFT methods were applied for understanding the difference in antitumor activity. Additionally, molecular docking into active site of the DNA Topo II enzyme was performed on 3QX3. PDB file in order to find out possible mechanism of antitumor effect. According to all obtained results showed that compounds 1b, 1c, and 1d could be potential drug candidates as new antitumor agents, and are promising for cancer therapy.

Computational insights into the protonation states of catalytic dyad in BACE1-acyl guanidine based inhibitor complex.

Developing small compound based drugs targeting the ß-secretase (BACE) enzyme is one of the most promising strategies in treatment of the Alzheimer's disease. As the enzyme shows the activity based on the acid-base reaction at a very narrow pH range, the protonation state of aspartic acids with the residue number 32 and 228 (Asp32 and Asp228), which forms the active site dyad, along with the protonation state of the ligand (substrate or inhibitor) play very critical role in interactions between the ligand and enzyme. Thus, understanding the nature of the protonation state of both enzyme's active site dyad and ligand is crucial for drug design in Alzheimer's disease field. Here we have investigated the protonation state of the Asp32 and Asp228 residues in the presence of a highly potent beta secretase inhibitor, containing acyl guanidine warhead that have recently been devised but not extensively studied. Our Quantum Mechanical, Molecular Dynamics and Docking studies on all the possible protonation states have suggested that the dyad residues are in di-deprotonated states in the presence of protonated inhibitor.

Fabrication of naturel pumice/hydroxyapatite composite for biomedical engineering.

BACKGROUND: We evaluated the Bovine hydroxyapatite (BHA) structure. BHA powder was admixed with 5 and 10 wt% natural pumice (NP). Compression strength, Vickers micro hardness, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction studies were performed on the final NP-BHA composite products. The cells proliferation was investigated by MTT assay and SEM. Furthermore, the antimicrobial activity of NP-BHA samples was interrogated. RESULTS: Variances in the sintering temperature (for 5 wt% NP composites) between 1000 and 1300 °C, reveal about 700 % increase in the microhardness (~100 and 775 HV, respectively). Composites prepared at 1300 °C demonstrate the greatest compression strength with comparable result for 5 wt% NP content (87 MPa), which are significantly better than those for 10 wt% and those that do not include any NP (below 60 MPa, respectively). CONCLUSION: The results suggested the optimal parameters for the preparation of NP-BHA composites with increased mechanical properties and biocompatibility. Changes in micro-hardness and compression strength can be tailored by the tuning the NP concentration and sintering temperature. NP-BHA composites have demonstrated a remarkable potential for biomedical engineering applications such as bone graft and implant.

Charge-Transfer Complex of p-Aminodiphenylamine with Maleic Anhydride: Spectroscopic, Electrochemical, and Physical Properties.

A new charge-transfer complex and the amide formed by the interaction between the electron donor of the p-aminodiphenylamine and the electron acceptor of maleic anhydride are investigated by spectroscopic methods. The amidation reaction is caused by proton and charge transfer between the maleic anhydride and p-aminodiphenylamine molecules. The Benesi-Hildebrand equation is used to determine the formation constant, the molar extinction coefficient and the standard Gibbs free energy of the complex by using UV/Vis spectroscopy. To reveal the electronic and spectroscopic properties of these molecules, theoretical computations are performed on the structures of maleic anhydride, p-aminodiphenylamine and the conformers of their charge-transfer complex. The charge-transfer complex and amidation reaction mechanism are also confirmed by IR and NMR spectroscopy and HRMS. The nature of the maleic anhydride-p-aminodiphenylamine complex is characterized by cyclic voltammetry, thermogravimetric analysis, XRD and SEM. Solid microribbons of this complex show higher thermal stability than p-aminodiphenylamine.

The efficacy of tyrosine kinase inhibitor dasatinib on colonic mucosal damage in murine model of colitis.

BACKGROUND AND OBJECTIVE: Ulcerative colitis is an inflammatory condition of the colon in the gastrointestinal system. Currently, the most potent medications used for ulcerative colitis produce no response in 20-30% of cases. There is a need for more efficient and reliable medications. Tyrosine kinase inhibitors have shown efficacy in some inflammatory diseases. Although dasatinib, a tyrosine kinase inhibitor, suppresses proinflammatory cytokines in colonic tissue, there are a few cases of hemorrhagic colitis with dasatinib. There is no study investigating the effect of dasatinib on experimental colitis. We aimed to investigate the effect of dasatinib in a colitis model induced with acetic acid in our study. METHODS: In the study, 24 male Sprague-Dawley rats randomly distributed into 4 groups of 6 rats each as control, dasatinib, colitis and dasatinib+colitis groups. For colitis induction, 4% acetic acid was used. Sacrificing of the rats was performed on the seventh day. Disease activity, morphologic and histological injury, superoxide dismutase, myeloperoxidase and malondialdehyde activity, TNFα and CD3 expression were assessed in colonic tissue. RESULTS: Apart from malondialdehyde, significant difference in all parameters between the control and colitis groups was determined. Difference between the colitis and colitis+dasatinib groups was not significant in only weight loss and biochemical parameters. Though dasatinib does not fully resolve the changes in colitis, there was significant regression. CONCLUSIONS: Dasatinib decreased the inflammation in a rodent model of colitis. It may be provide this effect by the suppression of TNFα. Dasatinib may be one of the treatment options for ulcerative colitis.

Studies of miscibility and specific interactions of antitumor-active anhydride copolymer and poly(ethylene glycol) blends.

The blending of polymers is of great interest, since the modification gives rise to diverse physical properties with the functionality of a polymer, without synthesis. Water-soluble antitumor-active poly(maleic anhydride-alt-acrylic acid) poly(MA-alt-AA) and poly(ethylene glycol) (PEG) blends were prepared by casting, and compatible properties were investigated by dilute solution viscometry. Viscosity measurements were made on ternary systems of polymer (1)/polymer (2)/solvent (H2O) and p-dioxane, at different concentrations of PEG and poly(MA-alt-AA). The interaction parameters Δß, µ, Δk, Δb, ß and α, which have been proposed, have been obtained using the viscosity data, to probe the miscibility of the polymer blends. The solid blends prepared were characterized with ATR-FTIR, (1)H-NMR, DTA and TGA.

Synthesis and swelling peculiarities of new hydrogels based on the macromolecular reaction of anhydride copolymers with γ-aminopropyltriethoxysilane.

This work describes the synthesis and macromolecular reactions of maleic anhydride (MA)-acrylamide (AAm) binary and MA-vinyl acetate (VA)- AAm ternary reactive copolymers with γ-aminopropyltriethoxysilane (APTS) as a polyfunctional crosslinker. Swelling parameters such as the start-time of the hydrogel-formation, initial rate of swelling, swelling rate constant, equilibrium swelling, and equilibrium water content (EWC) are determined for polymers/APTS/water systems with certain copolymer/crosslinker ratios (1.4/1 and 9/1). The formation of a hyperbranched network structure by the fragmentation of the side-chain reactive groups in the systems studied has also been confirmed by the Fourier Transform Infrared (FTIR) method.

Bactericidal permeability increasing protein gene polymorphism is associated with inflammatory bowel diseases in the Turkish population.

BACKGROUND/AIMS: Inflammatory bowel disease, a chronic inflammatory disease with unknown etiology, affects the small and large bowel at different levels. It is increasingly considered that innate immune system may have a central position in the pathogenesis of the disease. As a part of the innate immune system, bactericidal permeability increasing protein has an important role in the recognition and neutralization of gram-negative bacteria. The aim of our study was to investigate the involvement of bactericidal permeability increasing protein gene polymorphism (bactericidal permeability increasing protein Lys216Glu) in inflammatory bowel disease in a large group of Turkish patients. PATIENTS AND METHODS: The present study included 528 inflammatory bowel disease patients, 224 with Crohn's disease and 304 with ulcerative colitis, and 339 healthy controls. RESULTS: Bactericidal permeability increasing protein Lys216Glu polymorphism was found to be associated with both Crohn's disease and ulcerative colitis (P = 0.0001). The frequency of the Glu/Glu genotype was significantly lower in patients using steroids and in those with steroid dependence (P = 0.012, OR, 0.80; 95% confidence interval [CI]: 0.68-0.94; P = 0.0286, OR, 0.75; 95% CI: 0.66-0.86, respectively). There was no other association between bactericidal permeability increasing protein gene polymorphism and phenotypes of inflammatory bowel disease. CONCLUSIONS: Bactericidal permeability increasing protein Lys216Glu polymorphism is associated with both Crohn's disease and ulcerative colitis. This is the first study reporting the association of bactericidal permeability increasing protein gene polymorphism with steroid use and dependence in Crohn's disease.

The Syk Inhibitor Fostamatinib Decreases the Severity of Colonic Mucosal Damage in a Rodent Model of Colitis.

BACKGROUND AND AIMS: Inflammatory bowel disease is a chronic inflammatory disease of the gastrointestinal system. In some cases, current medications used for inflammatory bowel disease may not be enough for remission, creating a need for more potent and reliable medications. There is no study showing the efficacy of fostamatinib, with proven effects on some inflammatory diseases, on ulcerative colitis. In our study we planned to research the efficacy of fostamatinib, a spleen tyrosine kinase inhibitor, on acetic acid-induced colitis. METHODS: The study included 28 male Sprague-Dawley rats, randomly divided into control group, fostamatinib group, colitis group and fostamatinib + colitis group, each containing seven rats. Colitis induction was performed with 4% acetic acid. Colonic inflammation was assessed with disease activity index, macroscopic and histological damage scores, colonic myeloperoxidase, malondialdehyde and superoxide dismutase activity, and tumour necrosis factor alpha [TNFα], CD3, Syk, and phospho-Syk expression. RESULTS: There was a significant difference between the colitis and control groups in terms of all parameters. The disease activity index, macroscopic and microscopic damage scores, immunohistochemical TNFα, CD3, Syk, and phospho-Syk expression, and tissue myeloperoxidase activity were found to be significantly lower in the colitis + fostamatinib group compared with the colitis group. There was no significant difference between the two groups in terms of myeloperoxidase and malondialdehyde activity. CONCLUSIONS: Fostamatinib reduced the inflammatory damage in the experimental colitis. This effect may be due to suppression of TNFα, T-lymphocytes, and neutrophils in colonic mucosa via suppression of Syk. Fostamatinib may be an appropriate treatment alternative for ulcerative colitis. Further clinical studies are required to support this.

Tyrosine kinase-2 gene polymorphisms are associated with ulcerative colitis and Crohn's disease in Turkish Population.

BACKGROUND AND OBJECTIVE: Inflammatory bowel disease is a group of chronic inflammatory conditions affecting gastrointestinal tract. Lots of genes have been identified resulting in susceptibility to inflammatory bowel disease. Any polymorphism leading to functional modifications in tyrosine kinase-2 may precipitate excessive immune response in the intestinal mucosa. The aim of our study is to investigate the involvement of tyrosine kinase-2 polymorphisms in the patients with inflammatory bowel disease in Turkish population. METHODS: Four single nucleotide polymorphisms in tyrosine kinase-2 (rs280523, rs2304256, rs280519 and rs280496) were genotyped in 60 Crohn's disease, 151 ulcerative colitis patients and 89 unrelated healthy controls. These polymorphisms were detected by real-time polymerase chain reaction. RESULTS: The presence of genotype (CC) in rs2304256 and (AA) in rs280519 were found to increase the susceptibility to ulcerative colitis (P=0.024, 0.025, respectively). rs2304256 (CA) and rs280519 (AG) have provided protection against ulcerative colitis (P=0.021, 0.012, respectively). rs280519 (AG) was protective against Crohn's disease (P=0.045). rs2304256 (CC) increased the susceptibility to inflammatory Crohn's disease (P=0.014). The presence of rs2304256 (A) increased the susceptibility to perianal Crohn's disease (P=0.03). Both rs280519 and rs2304256 polymorphisms were associated with the requirement of corticosteroid and immunosuppressive therapy in ulcerative colitis. CONCLUSION: This study is the first demonstration of the single marker association of tyrosine kinase-2 polymorphisms with ulcerative colitis and Crohn's disease in Turkish population. They may be effective in the etiology of inflammatory bowel disease in our population. Disparity between our study and others may be related to ethnic differences.

The effect of synthesis media on the properties of substituted polyaniline/chitosan composites.

Substituted polyaniline/chitosan (sPANI/Ch) composites were chemically synthesized in H(2)SO(4) and CH(3)COOH synthesis media. Structural and physical properties of the composites were characterized by using FTIR, SEM, TGA, UV-vis, XRD techniques, and conductivity measurements. The effect of synthesis media on morphology, thermal stability, conductivity, and crystalline properties was investigated. Chemical interactions between substituted polyanilines and chitosan were explained using FTIR spectra results. The different morphological surfaces were observed in SEM images of the composites. The size of the substituted polyaniline/chitosan (sPANI/Ch) composites was in nanoscale, and the composites synthesized in acetic acid media showed smaller structures than those of H(2)SO(4) media and pure chitosan. It was interpreted from XRD results that the composites have amorphous structure and the PNEANI/Ch-CH(3)COOH composite has the highest crystallinity.

Surfactant formation efficiency of fluorocarbon-hydrocarbon oligomers in supercritical CO2.

We use dissipative particle dynamics simulations to explore the phase behavior and solution properties of ABCBA type model surfactants in near-supercritical CO(2) environment. We present design guidelines for functional surfactants with tunable properties. The block co-oligomers used in this study are made up of a CO(2)-phobic block having ethyl propionate and nine different types of ethylene monomers, flanked on either side by eight repeat units of fluorinated CO(2)-philic blocks. The most promising design block co-oligomer in the series is that with the longest CO(2)-phobic group in the ethylene monomers. For this particular oligomer, we systematically analyze the effect of concentration on the self-assembly behavior. Spherical micelles form in the 5%-65% volume fraction range for this oligomer, with the highest number of spherical micelles occurring at 45% surfactant in CO(2). When the volume fraction of the surfactant is increased from 70% to 85%, cylindrical micelles occur. We further investigate the effect of the length of the solvophilic fluorinated segments on self-assembly and find that stable micelles occur in a window of 8-14 repeat units. We find that the most critical contribution to stability is due to the mixing free energy between the chain tails residing in the outer layers and the interpenetrating molecules.