Effect of Transition Metals on Polysialic Acid Structure and Functions

Polysialic acid (PSA) is one of the most abundant glycopolymer present in embryonic brain, and it is known to be involved in key roles such as plasticity in the central nervous system, cell adhesion, migration and localization of neurotrophins. However, in adult brain, its expression is quite low. The exception to this is in Alzheimer′s disease (AD) brain, where significantly increased levels of polysilylated neural cell adhesion molecule (PSA‐NCAM) have been reported. Here, we confirm the role of PSA as a metal chelator, allowing it to decrease cytotoxicity caused by high levels of transition metals, commonly found in AD brain, and as a regulator of cell behavior. UV‐visible (UV‐vis) and circular dichroism (CD) spectroscopy, atomic force microscopy (AFM), and isothermal titration calorimetry (ITC) techniques were used to investigate the assembly of PSA–metals complexes. These PSA–metal complexes exhibited less toxicity compared to free metal ions, and in particular, the PSA–Cu²⁺ complex synergistically promoted neurite outgrowth in PC12 cells.     

Ultra-high strength Mg-9Gd-4Y-0.5Zr alloy with bi-modal structure processed by traditional extrusion

It is usual to observe that multi-scale structures can lead to combined strength and ductility both in aluminum alloys and steels, but related research has been seldom reported yet in magnesium alloys. In this study, applying traditional one step extrusion, we have successfully obtained a bimodal (Mg-9Gd-4Y-0.5Zr) alloy capable of ultra-high strength. The characterized sample reveal a bi-modal microstructure with two constitutions, i.e. stretched coarse-grain region with strong basal fiber texture and recrystallization fine-grain region. The bi-modal structured sample exhibit excellent mechanical properties with an ultimate strength 508 MPa and elongation 8% via 400 °C extrusion and subsequently 200 °C-60 h peak aging process. Ultra-high strength can be attributed to its strong extrusion texture in stretched coarse grains and dispersed nano-scale precipitates. This unique bimodal structure could be produced easily by one step extrusion, which is quite reliable and low costs in industrial applications of magnesium alloys with ultra-high strength as well as ideal ductility.     

Accelerated Design of Eutectic High Entropy Alloys by ICME Approach

Eutectic high entropy alloy with seven components is designed based on the integrated computational materials engineering (ICME) framework. The framework includes thermodynamic prediction using calculation of phase diagrams (CALPHAD), microstructure simulation using phase-field method, and experimental validation. The designed alloy shows the eutectic structure consisting of FCC and laves phase in the composition range from 8.25 to 10 at. pct Ta. The simulation and experimental results are co-related and a framework is proposed that can be used for high entropy alloy design subjected to various manufacturing processes.

     

Synthesis of nanostructured copper hexacyanidoferrate and its application in voltammeteric detection of salbutamol

Nanostructured copper hexacyanidoferrate has been synthesized and characterized using elemental analysis, atomic absorption spectroscopy, thermal and infrared spectral studies. The transmission electron microscopic studies of the synthesized material showed that it consisted of irregular oval and rod shaped particles with a size range 70–100 nm. Nanostructured copper hexacyanidoferrate modified glassy carbon electrode was characterized by cyclic voltammetery and nanostructured copper hexacyanidoferrate–carbon nanotube composite material modified glassy carbon electrode has been used for electrocatalytic oxidation of salbutamol. The electrode modified with composite material was found to reduce the peak potential of oxidation of salbutamol by nearly 90 mV.     

Preparation of CaCO3‐based biomineralized polyvinylpyrrolidone–carboxymethylcellulose hydrogels and their viscoelastic behavior

In the blend of natural and synthetic polymer‐based biomaterial of polyvinylpyrrolidone (PVP) and carboxymethylcellulose (CMC), fabrication of CaCO₃ was successfully accomplished using simple liquid diffusion technique. The present study emphasizes the biomimetic mineralization in PVP–CMC hydrogel, and furthermore, several properties of this regenerated and functionalized hydrogel membranes were investigated. The physical properties were studied and confirmed the presence of CaCO₃ mineral in hydrogel by Fourier transform infrared spectroscopy and Scanning electron microscopy. Moreover, the absorptivity of water and mineral by PVP–CMC hydrogel was studied to determine its absorption capacity. Further, the viscoelastic properties (storage modulus, loss modulus, and complex viscosity) of mineralized and swelled samples (time: 5–150 min) were measured against angular frequency. It is interesting to know the increase of elastic nature of mineralized hydrogel filled with CaCO₃ maintaining the correlation between elastic property and viscous one of pure hydrogel. All these properties of biomineralized hydrogel suggest its application in biomedical field, like bone treatment, bone tissue regeneration, dental plaque and tissue replacement, etc. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40237.     

Conversion of waste polystyrene through catalytic degradation into valuable products

Waste expanded polystyrene (EPS) represents a source of valuable chemical products like styrene and other aromatics. The catalytic degradation was carried out in a batch reactor with a mixture of polystyrene (PS) and catalyst at 450 °C for 30 min in case of Mg and at 400 °C for 2 h both for MgO and MgCO₃ catalysts. At optimum degradation conditions, EPS was degraded into 82.20±3.80 wt%, 91.60±0.20 wt% and 81.80±0.53 wt% liquid with Mg, MgO and MgCO₃ catalysts, respectively. The liquid products obtained were separated into different fractions by fractional distillation. The liquid fractions obtained with three catalysts were compared, and characterized using GC-MS. Maximum conversion of EPS into styrene monomer (66.6 wt%) was achieved with Mg catalyst, and an increase in selectivity of compounds was also observed. The major fraction at 145 °C showed the properties of styrene monomer. The results showed that among the catalysts used, Mg was found to be the most effective catalyst for selective conversion into styrene monomer as value added product.     

含硝基苯类化合物废水预处理技术研究进展

硝基苯类化合物是重要的化工原料和精细化工中间体,它性质稳定,属难降解有机物,不易被生物降解,对环境危害大。由于高浓度硝基苯类化合物对生物有抑制作用,难以生化降解,单一使用生化法处理高浓度硝基苯类废水不可行,因此必须在生化处理单元前进行预处理。通过预处理,改变硝基苯类化合物的分子结构,使之变成较易生物降解的化合物,降低废水的毒性,提高废水的可生化性,再用生化法处理,以达到消除环境污染的目的。     

Nanomedicine-Based Delivery Strategies for Breast Cancer Treatment and Management

Breast cancer is one of the most common types of cancer among women globally. It is caused by mutations in the estrogen/progesterone receptors and conventional treatment methods are commonly utilized. About 70–80 percent of individuals with the early-stage non-metastatic disease may be cured. Conventional treatment is far less than the optimal ratio, as demonstrated through the high mortality rate of women with this cancer. However, conventional treatment methods like surgery, radiotherapy, and chemotherapy are not as effective as expected and lead to concerns about low bioavailability, low cellular uptake, emerging resistance, and adverse toxicities. A nanomedicine-based approach is a promising alternative for breast cancer treatment. The present era is witnessing rapid advancements in nanomedicine as a platform for investigating novel therapeutic applications and modern intelligent healthcare management strategies. This paper focuses on nanomedicine-based therapeutic interventions that are becoming more widely accepted for improving treatment effectiveness and reducing undesired side effects in breast cancer patients. By evaluating the state-of-the-art tools and taking the challenges involved into consideration, various aspects of the proposed nano-enabled therapeutic approaches have been discussed in this review.     

Deciphering the Effect of Lysine Acetylation on the Misfolding and Aggregation of Human Tau Fragment 171IPAKTPPAPK180 Using Molecular Dynamic Simulation and the Markov State Model

The formation of neurofibrillary tangles (NFT) with β-sheet-rich structure caused by abnormal aggregation of misfolded microtubule-associated protein Tau is a hallmark of tauopathies, including Alzheimer’s Disease. It has been reported that acetylation, especially K174 located in the proline-rich region, can largely promote Tau aggregation. So far, the mechanism of the abnormal acetylation of Tau that affects its misfolding and aggregation is still unclear. Therefore, revealing the effect of acetylation on Tau aggregation could help elucidate the pathogenic mechanism of tauopathies. In this study, molecular dynamics simulation combined with multiple computational analytical methods were performed to reveal the effect of K174 acetylation on the spontaneous aggregation of Tau peptide ¹⁷¹IPAKTPPAPK¹⁸⁰, and the dimerization mechanism as an early stage of the spontaneous aggregation was further specifically analyzed by Markov state model (MSM) analysis. The results showed that both the actual acetylation and the mutation mimicking the acetylated state at K174 induced the aggregation of the studied Tau fragment; however, the effect of actual acetylation on the aggregation was more pronounced. In addition, acetylated K174 plays a major contributing role in forming and stabilizing the antiparallel β-sheet dimer by forming several hydrogen bonds and side chain van der Waals interactions with residues I171, P172, A173 and T175 of the corresponding chain. In brief, this study uncovered the underlying mechanism of Tau peptide aggregation in response to the lysine K174 acetylation, which can deepen our understanding on the pathogenesis of tauopathies.