Adsorption of BSA onto hexagonal mesoporous silicate loaded by APTES and tannin: Isotherm,thermodynamic and kinetic studies

In the present study, hexagonal mesoporous silica (HMS) was synthesized and modified by tannic acid as a natural poly-phenol and amine (TA-A-HMS) and was applied for the adsorption of bovine serum albumin (BSA) from aqueous media. To investigate the structure of HMS and TA-A-HMS, SEM, TEM, XRD, BET and FTIR analysis were applied. The effects of pH, adsorbent dosage, contact time and temperature on the BSA adsorption were studied. After modification, BET surface area of HMS was reduced from 885?m²/g to 51?m²/g which confirms the presence of tannin and amine groups that inhibit the adsorption of nitrogen molecules. According to the results of equilibrium data, it is shown that Langmuir isotherm with maximum adsorption capacity of 1000?mg/g is the predominant model and adsorption is mono-layer. Kinetic and thermodynamic studies also reveal that adsorption kinetic followed by pseudo-second order model and the adsorption process is exothermic.     

Conducting Polymer Microcups for Organic Bioelectronics and Drug Delivery Applications

An ideal neural device enables long‐term, sensitive, and selective communication with the nervous system. To accomplish this task, the material interface should mimic the biophysical and the biochemical properties of neural tissue. By contrast, microfabricated neural probes utilize hard metallic conductors, which hinder their long‐term performance because these materials are not intrinsically similar to soft neural tissue. This study reports a method for the fabrication of monodisperse conducting polymer microcups. It is demonstrated that the physical surface properties of conducting polymer microcups can be precisely modulated to control electrical properties and drug‐loading/release characteristics.     

The effect of grinding media on suspensions,microstructures, and comprehensive electrical properties of ZnO varistors

Journal of Materials Science: Materials in Electronics - The aim of this work is to find a proper grinding medium that produce the best suspension of additives in order to fabricated ZnO varistors...     

PVT‐compensated low‐voltage and low‐power CMOS LNA for IoT applications

In this paper, a low‐noise amplifier (LNA) with process, voltage, and temperature (PVT) compensation for low power dissipation applications is designed. When supply voltage and LNA bias are close to the subthreshold, voltage has significant impact on power reduction. At this voltage level, the gain is reduced and various circuit parameters become highly sensitive to PVT variations. In the proposed LNA circuit, in order to enhance efficiency at low supply voltage, the cascade technique with g_m boosting is used. To improve circuit performance when in the subthreshold area, the forward body bias technique is used. Also, a new PVT compensator is suggested to reduce sensitivity of different circuit's parameters to PVT changes. The suggested PVT compensator employs a current reference circuit with constant output regarding temperature and voltage variations. This circuit produces a constant current by subtracting two proportional to absolute temperature currents. At a supply voltage of 0.35 V, the total power consumption is 585 μW. In different process corners, in the proposed LNA with PVT compensator, gain and noise figure (NF) variations are reduced 10.3 and 4.6 times, respectively, compared to a conventional LNA with constant bias. With a 20% deviation in the supply voltage, the gain and noise NF variations decrease 6.5 and 34 times, respectively.     

Correction to: Monitoring and Predicting Saltwater Intrusion via Temporal Aquifer Vulnerability Maps and Surrogate Models

Water Resources Management -     

Defocus estimation from stroboscopic cryo-electron microscopy data

Defocus estimation is an important step for improving the resolution of single particle reconstructions. It can be troublesome to estimate the defocus from low-dose cryo-electron microscopy (cryo-EM) data, particularly if there is not sufficient contrast present in the Fourier transform of the micrograph. Most existing approaches estimate the defocus from the presence of Thon rings within the power spectrum, employing image enhancement techniques to highlight these rings. In this paper, an approach to estimating the defocus from a stroboscopic image series is described. The image series is used to obtain two statistical metrics: figure of merit (FOM) and Q-factor. These metrics have been used to estimate the defoci from low-dose stroboscopic cryo-EM data consisting of a variable number of images.     

Effect of seed layers on low-temperature,chemical bath deposited ZnO nanorods-based near UV-OLED performance

Low-temperature wet chemical bath deposition (CBD) method is one of the most efficient and least hazardous solution-based techniques which is widely employed to grow ZnO NRs. In CBD method, a seed layer is usually deposited on the substrate. In this paper, high quality ZnO and aluminum doped ZnO (AZO) seed layers are sputtered on the indium tin oxide (ITO) coated glass. In continue, aligned ZnO NRs are grown on the AZO and ZnO seed layers via CBD technique. The effect of the growth time and seed layer on the physical properties of as-grown ZnO NRs are investigated. According to the results, the seed layer plays an essential role on the growth orientation and growth rate of the ZnO NRs. The ZnO NRs grown on AZO seed layer are more aligned rather than ZnO seed layer due to their higher texture coefficients. The relative photoluminescence (PL) intensity ratio of near band emission (NBE) to deep level emission (DLE) (I_NBE/I_DLE) for the ZnO NRs grown on AZO and ZnO seed layers are calculated as 7.45 and 2.62, respectively. To investigate the performance of the as-grown ZnO NRs, near ultraviolet organic light-emitting diodes (UV-OLEDs) using ZnO NRs array as n-type material and poly [2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV) conjugated polymer as p-type material have been fabricated. The total concentration of traps ($N_t$), the characteristic energies ($E_t$) and the turn-on voltages for the devices with the structures of ITO/AZO/ZnO NRs/MEH-PPV/Al (device A) and ITO/ZnO/ZnO NRs/MEH-PPV/Al (device B) are attained 7.65 × 10¹⁶ and 7.75 × 10¹⁶ cm^?3, 0.232 and 0.206 eV, 23 and 21 V, respectively. Moreover, based on the electroluminescence (EL) spectra, the NBE peaks for device A and B are obtained nearly in the wavelengths of 382 and 388 nm, respectively. Finally, various charge carrier transportation processes of prepared UV-OLEDs have been studied, systematically.     

Synthesis and characterization of novel biodegradable water dispersed poly(ether-urethane)s and their MWCNT-AS nanocomposites functionalized with aspartic acid as dispersing agent

New biodegradable poly(ether-urethane)s (PEU)s were synthesized via the reaction of L-leucine anhydride cyclo-peptide, polyethylene glycol-1000 and hexamethylene diisocyanate. Then, they were end-functionalized with aspartic acid (AS) as a dispersing agent and were dispersed in water. MWCNTs were also functionalized by AS under microwave irradiation. Polymer/MWCNT-AS composites and polymer/MWCNT-AS water dispersed composites were prepared through an ultrasound-assisted method. We have designed these PEUs with two different structural architectures (PA1and PA2) which can be readily dispersed in water (PA1-D and PA2-D). The structure and properties of the polymers, MWCNTs-AS and PEUs/MWCNTs-AS composites were investigated by FTIR and NMR spectroscopy methods and FE-SEM, TEM and TGA techniques. The particle sizes of the resulting PA1-D and PA2-D dispersions were in the range of 200–300 nm. The results showed that by increasing MWCNT-AS loading, the degradation rate and particle sizes of the dispersed composites decreased, while thermal stability and dispersion stability of the composite systems increased. The degradation tests of polymers and their composites in PBS at 37 °C after 10 days showed weight losses ranging from 23 to 44 and 17–37%, respectively. The cytotoxicity study of polymers using the direct-contact test on L929 mouse fibroblast cell line showed no toxicity. Other properties such as thermal stability, dispersion’s particle size, degradation rate and morphology of the composites were studied, and the effect of simultaneous dispersion of MWCNTs-AS and PEUs in water on the properties of the resulting mixtures was studied. We suggest that these polymers have tunable properties which may potentially be considered for drug carriers’ studies.