Grain boundary sliding and non-constancy strain during stress relaxation of pure Mg.

Stress relaxation during plastic deformation has been reported to improve ductility of metallic materials. In this study, the stress relaxation behaviour in pure magnesium is investigated during interrupted uniaxial tensile tests. During intermittent stopping of the machine for relaxation studies, the total strain is expected to remain constant. However, an anomalous non-constancy in total strain is observed in the present work. The total strain increases with relaxation time. Additional in-situ tensile tests indicate that the non-constant total strain is restricted only in the gauge area of the specimen, indicating a likely shear dominated deformation such as grain boundary sliding (GBS) responsible for the anomalous behaviour. The role of GBS during relaxation is studied using the deformation induced evolution of surface inhomogeneity. Determinations of surface profiling step heights at grain boundaries and inclination of grains were used to quantify the effect of GBS. The estimated activation volume of 4.35 b 3 further confirms the role of slip induced GBS on the deformation. A new stress relaxation model accommodating GBS is proposed and is found to fit the experimental data accurately.

Hips in cerebral palsy: A clinico-radiological evaluation of hip subluxation in cerebral palsy.

Background: The study was done on children with cerebral palsy in the ages of 2-18 years, with focus on hip subluxation. The objectives of the study were to look at the distribution of different types of CP in the target population; the prevalence of hip subluxation and its association with types and severity of CP. Methods: This is a cross sectional descriptive observational study, done on a hospital out-patient setting. Children with cerebral palsy of ages 2-18 years were recruited and clinically evaluated. Radiological evaluation of the pelvis was done for all subjects. Primary outcome measure was presence of hip subluxation described as Migration Percentage >30% in one or both hips. Prevalence of subluxation and its association with various subtypes of CP were assessed. Results: 203 subjects with cerebral palsy underwent the study. Spastic type of presentation constituted the majority (82.8%). Quadriplegic distribution (53.2%) and functional level of GMFCS 5 (39.4%) were most prevalent. Hip subluxation was noted in 105 of the 203 children with CP (51.7%). 3 patients had complete dislocation of the hip (1.4%). There was an increased prevalence of hip subluxation noted with increasing GMFCS E&R score as well as increasing topographical distribution, which were both statistically significant on univariate analysis (p < 0.005). On multivariate analysis, it was found that neither topographical distribution nor GMFCS E&R score were independent risk factors. Conclusions: Hip subluxation is a significant, debilitating and common treatable complication in children with CP. Subjects with widespread topographical distribution and poor functional ambulatory status are at an increased risk of developing hip subluxation. There also exists a correlation between GMFCS scores and topographical classification and hence, neither are risk factors independent of each other. This study is a first of its kind in the Indian scenario and it hopes to be a step in the direction towards risk stratification, early diagnosis and prompt specific treatment of hip complications in children with cerebral palsy.

Emerging Nanotechnological Applications in Preserving and Improving the Shelf Life of Food.

The ever-growing demand for safe and nutritious food has activated the scrutinization of innovative approaches to enhance food preservation and extended shelf life. Nanotechnology has progressed by making a significant contribution to the food industry at the nanoscale level and appeared as a promising avenue for these challenges. Various nanomaterials have been employed to preserve and extend the shelf life of a variety of food products. Since most harvested fruits and vegetables have a perishable nature, they cannot be preserved in natural circumstances for a long period. Due to a range of unique qualities, nanotechnology-related shelf life extension technologies can compensate for the limitations of normal preservation procedures. The encapsulation of nutraceuticals increases their stability and bioavailability, resulting in beneficial effects on humans. Nanoparticles are used as carriers of health-promoting and/or functional substances in product formulations. They have shown excellent effectiveness in encapsulating bioactive substances and retaining their qualities to ensure their functioning (antioxidant and antibacterial) in food products. This review focuses on the current developments in nanotechnology and their application for improving shelf life and food preservation techniques. Here we excavated the implementation of different types and forms of nanostructured materials (NSMs), from inorganic metals, metal oxides, and their nanocomposites to nano-organic materials incorporating bioactive chemicals in the food system. This review also focuses on exploring the slow and sustainable release of the bioactive compounds, and nutrients enriching the taste and sensory characteristics of the food. Throughout the paper, we dug deep into the regulatory, food safety, and assessment concerns about nanotechnology. The review provides a deep understanding of the developing landscape of nanotechnological applications, challenges, and future opportunities revolutionizing the preservation and extended shelf life of food products.

The role of nanocomposites against biofilm infections in humans.

The use of nanomaterials in several fields of science has undergone a revolution in the last few decades. It has been reported by the National Institutes of Health (NIH) that 65% and 80% of infections are accountable for at least 65% of human bacterial infections. One of their important applications in healthcare is the use of nanoparticles (NPs) to eradicate free-floating bacteria and those that form biofilms. A nanocomposite (NC) is a multiphase stable fabric with one or three dimensions that are much smaller than 100 nm, or systems with nanoscale repeat distances between the unique phases that make up the material. Using NC materials to get rid of germs is a more sophisticated and effective technique to destroy bacterial biofilms. These biofilms are refractory to standard antibiotics, mainly to chronic infections and non-healing wounds. Materials like graphene and chitosan can be utilized to make several forms of NCs, in addition to different metal oxides. The ability of NCs to address the issue of bacterial resistance is its main advantage over antibiotics. This review highlights the synthesis, characterization, and mechanism through which NCs disrupt Gram-positive and Gram-negative bacterial biofilms, and their relative benefits and drawbacks. There is an urgent need to develop materials like NCs with a larger spectrum of action due to the rising prevalence of human bacterial diseases that are multidrug-resistant and form biofilms.

Ultra-gentle soft robotic fingers induce minimal transcriptomic response in a fragile marine animal.

Tessler et al. demonstrate that a 'soft' robot causes less stress to a jellyfish while handling compared to a traditional 'hard' robot.

Spectroscopic studies on some fluorescent mixed-ligand titanium(IV) complexes.

A novel route to synthesize some titanium(IV) complexes containing acetylacetone, straight chain carboxylic acid and hydroxycarboxylic acid ligands has been investigated. Complexes with the general formula [Ti(acac)Cl(2-n)(OOCR*)(n)(OOCC(15)H(31))] (where Hacac=acetylacetone, R*COOH=hydroxycarboxylic acids and n=1 or 2) have been isolated and characterized. Molecular weight determinations indicated mononuclear nature of the complexes. LMCT bands were observed in the electronic spectra. Infrared spectra suggested bidentate nature of the ligands. Fluorescent behaviour of the complexes was noticed on the basis of fluorescence spectra. Powder XRD indicated them to be semi-crystalline having the crystallite size in 136-185 nm range. Transmission electron microscopy (TEM) indicated spherical particles of ~ 200 nm diameter. On the basis of physico-chemical studies, it is suggested that titanium is having coordination number 7 or 8 in these complexes.

Substitution reactions of thorium(IV) acetate to synthesize nano-sized carboxylate complexes.

Some mixed-ligand thorium(IV) complexes with the general formula [Th(OOCCH(3))(4-n)L(n)] (L=anions of myristic, palmitic or stearic acid and n=1-4) have been synthesized by the stepwise substitution of acetate ions of thorium(IV) acetate with straight chain carboxylic acids in toluene under reflux. The complexes were characterized by elemental analyses, spectral (electronic, infrared, NMR and powder XRD) studies, electrical conductance and magnetic susceptibility measurements. Doubly and triply bridged coordination modes of the ligands were established by their infrared spectra and nano-size of the complexes by powder XRD. Room temperature magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes showed pi-->pi*, n-->pi* and charge transfer transitions. Molar conductance values indicated the complex to be non-electrolytes. These are a new type of mixed-ligand thorium(IV) complexes for which a nano-sized, oxygen bridged polymeric structure has been established on the basis of physico-chemical studies.