A Cellulosic Fruit Derived from Nerium oleander Biomaterial: Chemical Characterization and Its Valuable Use in the Biosorption of Methylene Blue in a Batch Mode

Cellulose substrate waste has demonstrated great potential as a biosorbent of pollutants from contaminated water. In this study, Neriumoleander fruit, an agricultural waste biomaterial, was used for the biosorption of methylene blue from synthetic solution. Fourier-transform infrared (FTIR) spectroscopy indicated the presence of the main absorption peak characteristics of cellulose, hemicellulose, and lignin compositions. X-ray diffraction (XRD) pattern exhibited peaks at 2θ = 14.9° and 2θ = 22°, which are characteristics of cellulose I. Scanning electron microscopy (SEM) showed a rough and heterogeneous surface intercepted by some cavities. Thermogravimetric analysis (TGA) showed more than a thermal decomposition point, suggesting that Nerium fruit is composed of cellulose and noncellulosic matters. The pHpzc value of Nerium surface was experimentally determined to be 6.2. Nerium dosage, pH, contact time, dye concentration, and temperature significantly affected the adsorption capacity. The adsorption capacity reached 259 mg/g at 19 °C. The mean free energy ranged from 74.53 to 84.52 KJ mol−1, suggesting a chemisorption process. Thermodynamic parameters define a chemical, exothermic, and nonspontaneous mechanism. The above data suggest that Nerium fruit can be used as an excellent biomaterial for practical purification of water without the need to impart chemical functionalization on its surface.

Synthesis and Characterization of Pyrazine Derived Compounds as Potential Materials for Hole Transporting Layer (HTL)

Three simple compounds that have the potential as a hole transporting layer (HTL) based on pyrazine derivatives conjugated with electron donor groups in the form of triphenylamine have been successfully synthesized and characterized. The synthesis began with a substitution reaction at high temperatures between 4-bromoaniline and 4-iodoanisole to produce 4-bromo-N,N-bis(methoxyphenyl)-aniline, followed by substitution of bromo atoms with tributylstanum at low temperatures and inert atmosphere (N2) producing 4-methoxy-N-(4-(tributylstanyl)phenyl)aniline. The conjugation reaction was carried out through a Stille coupling reaction between 1,2-bis (4-bromophenyl)ethane-1,2-dione with 4-methoxy-N-(4-(tributylstanyl)phenyl) aniline at high temperatures with the aid of a Pd(PPh3)4 catalyst in an inert atmosphere (N2). The reaction was continued with the imination reaction with 3 compounds, i.e., 1,2-diaminobenzene, 3,3-diaminobenzidine and 2,3-diaminopiridin to produce three HTL compounds that were namely 4’,4”-(quinoxaline-2,3-diyl)bis (N,N-bis(4(methoxyphenyl)-[1,1’-biphenyl]-4-amine) (DNB), 4’,4’’’,4’’’’’,4’’’’’’’-([6,6’-biquinoxaline]-2,2’,3,3’-tetrayl) tetrakis(N,N-bis(4-methoxyphenyl)- [1,1’-biphenyl] -4-amine) (bDNB), and 4’,4’’’-(pyrido[2,3-b]pyrazine-2,3-diyl)bis(N,N-bis (4-methoxyphenyl)-[1,1’-biphenyl]-4-amine) (DNP). The optical and electrochemical properties of DNB, bDNB, and DNP were analyzed by UV-Vis and Differential Pulse Voltammetry (DPV). The optical and electrochemical properties show the energy levels of the HOMO and LUMO of the three compounds. Hence their potential can be estimated as HTL compounds. The three compounds show λmax of 348 nm, 356 nm, and 350 nm for DNB, bDNB, and DNP. Based on DPV results, the HOMO values for DNB, bDNB, and DNP are -5.03 eV, -5.02 eV, and -4.98 eV and LUMO values of -2.46 eV, -2.76 eV and -2.87 eV, respectively. The three compounds' thermal properties were analyzed using TGA, with the results showing that the three compounds had good thermal resistance with a decomposition point above 400°C. Based on optical, electrochemical, and thermal analysis, DNB and bDNB have almost the same properties. Thus, it is expected that the three compounds have the potential as HTL material, with DNB and bDNB better than DNP.

Effect of Structure on the Thermal-Mechanical Performance of Fully Ceramic Microencapsulated Fuel

The effect of non-fuel part size on the thermal-mechanical performance of fully ceramic microencapsulated (FCMTM) Fuel was investigated, and the non-fuel part size was selected according to integrity maintaining of non-fuel part and silicon carbide (SiC) layers. The non-fuel part size can affect the FCMTM temperature and stress distribution greatly by changing the distance between tristructural isotropic (TRISO) particles. The maximum temperature of SiC matrix increased from 1220 K to 1450 K with the non-fuel part size increasing from 100 μm to 500 μm, and the matrix temperature of all the samples was lower than the decomposition point of SiC ceramics. The maximum hoop stress decreased with non-fuel part size, but the inner part exhibiteda crosscurrent trend. The inner part of the SiC matrix lost structure integrity because of the large hoop stress caused by the deformation of TRISO particles, however, the non-fuel parts of FCMTM pellet may maintain their integrity when the non-fuel part size was larger than 300 μm. SiC layers hoop stress increased with non-fuel part size, and the failure probability of SiC layer was lower than 2.2 × 10−4 for the FCMTM pellet with small non-fuel part size. The integrity of non-fuel and SiC layers can be maintained for the FCMTM pellet with the non-fuel part size from 300 μm to 400 μm.

Improvement of Thermal Stability of Cassava Starch Films from the Incorparation of Bentonite Clay

This study considered the effect of modified and unmodified bentonite clay on the thermal properties of films based on cassava starch. The bentonite clay was modified in the presence of cetyl trimethyl ammonium bromide (CTAB). The attainment of exfoliated or intercalated nanocomposite was characterized by X-ray diffraction (XRD) and Fourier transform by infrared radiation (FTIR). In XRD, it was verified that the cassava starch dispersed the modified clay in an exfoliated way and unmodified clay in an intercalated way. In the FTIR it was characterized that the cassava starch interacted more with the modified bentonite clay compared to unmodified. Finally, thermogravimetric curves showed the thermal property of the starch films concluding that the modified clay was the reinforcing material that contributed the most to the thermal stability of the cassava starch film, retarding its decomposition point, around 35oC , in relation to the pure starch film.

Preliminary Analysis of a Fully Ceramic Microencapsulated Fuel Thermal–Mechanical Performance

In this paper, a two-dimensional characteristic unit was used to simulate the thermal–mechanical performance of a fully ceramic microencapsulated (FCM) fuel pellet, and the criterion of FCM structure integrity was discussed. FCM structure integrity can be reflected though the integrity of the silicon carbide (SiC) matrix or SiC layers because of the excellent fission retention capability of SiC ceramics. The maximum temperature of the SiC matrix under normal conditions of the pressure water reactor (PWR) environment was about 1390 K, which was lower than the decomposition point of SiC. The maximum hoop stress of the SiC matrix, especially the inner part, was up to about 1200 MPa, and the hoop stress of the non-fuel region part was lower than the inner part, which can be attributed to the deformation of tristructural-isotopic (TRISO) particles. The hoop stress of the SiC layers at the end of life was only about 180 MPa, which is much lower than the strength of the chemical vapor deposition (CVD)-SiC. The failure probability of the SiC layer was lower than 9 × 10−5; thus, the integrity of SiC layers and the fission retention capability were maintained. The structure integrity of FCM fuel was broken because the SiC matrix cracked.

Antibiofilm Activity of Polyamide 11 Modified with Thermally Stable Polymeric Biocide Polyhexamethylene Guanidine 2-Naphtalenesulfonate

The choice of efficient antimicrobial additives for polyamide resins is very difficult because of their high processing temperatures of up to 300 °C. In this study, a new, thermally stable polymeric biocide, polyhexamethylene guanidine 2-naphtalenesulfonate (PHMG-NS), was synthesised. According to thermogravimetric analysis, PHMG-NS has a thermal degradation point of 357 °C, confirming its potential use in joint melt processing with polyamide resins. Polyamide 11 (PA-11) films containing 5, 7 and 10 wt% of PHMG-NS were prepared by compression molding and subsequently characterised by FTIR spectroscopy. The surface properties were evaluated both by contact angle, and contactless induction. The incorporation of 10 wt% of PHMG-NS into PA-11 films was found to increase the positive surface charge density by almost two orders of magnitude. PA-11/PHMG-NS composites were found to have a thermal decomposition point at about 400 °C. Mechanical testing showed no change of the tensile strength of polyamide films containing PHMG-NS up to 7 wt%. Antibiofilm activity against the opportunistic bacteria Staphylococcus aureus and Escherichia coli was demonstrated for films containing 7 or 10 wt% of PHMG-NS, through a local biocide effect possibly based on an influence on the bacterial eDNA. The biocide hardly leached from the PA-11 matrix into water, at a rate of less than 1% from its total content for 21 days.

Spectroscopic, thermal, second order and third order NLO studies of N, N’ -dimethyl urea crystal

Nonlinear optical (NLO) crystals are classified into organic, inorganic and semi organic crystals and these crystals are used in the fields of optical communication, optical computing, frequency doubling, optical data processing and opto electronics. In this work an organic NLO crystal namely DMU crystal was prepared. Slow evaporation technique was adopted to grow the single crystals of DMU after the growth period of 35 days. The harvested crystals have been subjected to various characterization techniques like XRD, FTIR, FT-Raman, TG/DTA, SHG, EDAX, impedance, optical and Z-scan studies. From the studies, is observed that DMU crystal has orthorhombic structure and it has the melting point at 105 oC and has the decomposition point at 275 oC. The relative SHG efficiency of DMU crystal was found to be more than one and third order NLO parameters were evaluated. The optical band gap of DMU crystal was found to be 5.008 eV.The results from various studies were analyzed.

Spectroscopic, thermal, second order and third order NLO studies of N, N’ -dimethyl urea crystal

Nonlinear optical (NLO) crystals are classified into organic, inorganic and semi organic crystals and these crystals are used in the fields of optical communication, optical computing, frequency doubling, optical data processing and opto electronics. In this work an organic NLO crystal namely DMU crystal was prepared. Slow evaporation technique was adopted to grow the single crystals of DMU after the growth period of 35 days. The harvested crystals have been subjected to various characterization techniques like XRD, FTIR, FT-Raman, TG/DTA, SHG, EDAX, impedance, optical and Z-scan studies. From the studies, is observed that DMU crystal has orthorhombic structure and it has the melting point at 105 oC and has the decomposition point at 275 oC. The relative SHG efficiency of DMU crystal was found to be more than one and third order NLO parameters were evaluated. The optical band gap of DMU crystal was found to be 5.008 eV.The results from various studies were analyzed.

Experimental Study on the Preparation Process of Binary Carbonate Salts

Ten kinds of binary carbonate salts with different ratio were respectively prepared by two kinds of preparation processes and the research on thermo-physical properties, thermal stability and component analysis was worked respectively by Differential Scanning Calorimetry instrument and XRD analytical instrument. The results showed: There was little difference on melting point and decomposition point between the samples prepared by two kinds of methods and well matched with that of reference phase diagram; For the preparation of mixed carbonate, static melting method was superior to the simple mechanical grinding method through TG and DSC curves of multiple cycles; There was no new material produced in both two kinds of preparation processes from the XRD composition analysis.

TWO CURVELETS VARIATIONAL MODELS DEPEND ON DECOMPOSITION SPACES

Wavelet has become an appealing image processing technique, due to the fact that the sparseness of wavelet expansion is equivalent to smoothness measure in Besov spaces so that the regularization of image can be performed by manipulating its wavelet coefficients. Unfortunately, wavelets have good performance especially at representing point singularities, but they fail to efficiently represent object edges. As one of computational harmonic analysis tools, curvelets have an essentially optimal representation of objects which is C2 away from a C2 edge. In this paper, we first apply constraint of curvelet-type decomposition spaces as a regularizing term to variational model for image denoising. Based on the equivalent relationship between semi-norm of curvelet-type decomposition spaces and the weighted curvelet coefficients, solution to the proposed model approximately equals to different curvelet shrinkages. As a second contribution, we also propose another image restoration model from image decomposition point of view. Furthermore, an equivalent theorem of two proposed models is given. Finally, the experiment results show the superiority of proposed models over traditional wavelet-based ones.