Harnessing the Flexibility of Lightweight Cellulose Nanofiber Composite Aerogels for Superior Thermal Insulation and Fire Protection

Thermally insulating materials from renewable and readily available resources are in high demand for ecologically beneficial applications. Cellulose aerogels made from lignocellulosic waste have various advantages. However, they are fragile and breakable when bent or compressed. In addition, cellulose aerogels are flammable and weather-sensitive. Hence, to overcome these problems, this work included the preparation of polyurethane (PU)-based cellulose nanofiber (CNF) aerogels that had flexibility, flame retardancy, and thermal insulation. Methyl trimethoxysilane (MTMS) and water-soluble ammonium polyphosphate (APP) were added to improve the cross-linking, hydrophobicity, and flame-retardant properties of aerogels. The flexibility of chemically cross-linked CNF aerogels is enhanced through the incorporation of polyurethane via the wet coagulating process. The aerogels obtained during this study have exhibited low weight (density: 35.3-91.96 kg/m3) together with enhanced hydrophobic properties, flame retardancy, and decreased thermal conductivity (26.7-36.7 mW/m K at 25 °C). Additionally, the flame-retardant properties were comprehensively examined and the underlying mechanism was deduced. The aerogels prepared in this study are considered unique in the nanocellulose aerogel category due to their integrated structural and performance benefits. The invention is considered to substantially contribute to the large-scale manufacture and use of insulation in construction, automobiles, and aerospace.

Recent advances in hydrophobic nanocellulose aerogels for oil spill applications: A review

In a rapidly growing world, petroleum is used extensively in various industries, and the extraction, processing, and transportation of petroleum generates large amounts of petroleum-containing wastewater. Conventional oil/water separation methodologies are often ineffective and costly. Nanocellulose-based aerogels (NA) have emerged as a possible solution to this problem. However, hydrophobic modification is required for effective use in oil/water separation. This review on materials commonly used in these processes and outlines the requirements for adsorbent materials and methods for creating unique lipophilic surfaces. New trends in hydrophobization methods for NA are also discussed. Additionally, it includes the development of composite nanocellulose aerogels (CNAs) and cellulose based membrane specially developed for oil/water (o/w) separation considering different separation requirements. This analysis also examines how CNAs have evolved by introducing special properties that facilitate oil collection or make the adsorbent recyclable. We also discuss the difficulties in creating effective NAs for these important applications in a changing society, as well as the difficulties in creating oil recovery equipment for oil spill cleanup.

Insights into thermal degradation kinetics and liquid crystalline behavior of cellulose nanocrystals from the waste of Cajanus cajan (pigeon pea)

Cellulose nanocrystals (CNCs) are essential for advancing nanotechnology and modern science. This work used the Cajanus cajan stem, an agricultural waste, as a lignocellulosic mass, which can serve as a supply of CNCs. After extraction from the Cajanus cajan stem, CNCs have been thoroughly characterized. FTIR (Infrared Spectroscopy) and ssNMR (solid-state Nuclear Magnetic Resonance) successfully validated eliminating additional components from the waste stem. The ssNMR and XRD (X-ray diffraction) were utilized to compare the crystallinity index. For structural analysis, the XRD of cellulose I_β was simulated to compare with the extracted CNCs. Various mathematical models inferred thermal stability and its degradation kinetics to ensure its high-end applications. Surface analysis established the rod-like shape of the CNCs. Rheological measurements were performed to gauge the liquid crystalline properties of CNC. The anisotropic liquid crystalline CNCs' birefringence proves that the Cajanus cajan stem is a promising resource for making CNCs for cutting-edge applications.

Surfactant Assisted In Situ Synthesis of Nanofibrillated Cellulose/Polymethylsilsesquioxane Aerogel for Tuning Its Thermal Performance

Nanofibrillated cellulose (NFC) and polymethylsilsesquioxane (PMSQ) based aerogel are prepared by the sol-gel method. The objective of this work is to study the impact of surfactant and base catalyst on the thermal and mechanical performance of the corresponding aerogel. The rheological premonitory assists in predicting the bulk properties of the aerogel. The chemical structure of the aerogel is studied by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and solid-state nuclear magnetic resonance (NMR). X-ray microtomographic (XMT) analysis confirms the homogeneous and monolithic structure of the aerogel. The lowest thermal conductivity is achieved as 23.21 mW m^-1 K^-1 with V-0 and HBF rating through UL-94 test. Thermal performance of aerogels is cross-verified through modeling and simulation in COMSOL multiphysics platform. The mechanical properties of aerogel are evaluated by monolithic compression test in axial and radial compression test up to 90% strain, cyclic compression loading-unloading, and reloading test, flexural test, and dynamic mechanical analysis. The time-temperature analysis has shown around 5 °C temperature difference in the middle of the room after using the aerogel panel at the exposed surface, which assists in the practical application of the synthesized aerogel panel.

Charcot-Marie-Tooth Disease Type 4C and Autosomal Dominant Heterozygous Ichthyosis Vulgaris, with Bilateral Hearing Loss: A Novel Association with Review of Literature

A 3-year-old boy, firstborn to nonconsanguineous parents, presented with motor development delay and floppiness of bilateral lower limbs since birth. No significant family history presented at time of check-up. He could stand with support, eat with a spoon without spillage, and speak in two-word sentences. There was no history suggestive of cranial nerve impairment. Examination revealed normal head circumference, dry, scaly skin lesions on the trunk, distal weakness with sluggish deep tendon reflexes in bilateral lower limbs, and a high stepping gait. Nerve conduction studies revealed demyelinating polyneuropathy. Brain stem-evoked response audiometry testing revealed auditory neuropathy. Clinical exome sequencing revealed a known pathogenic variant of 3325C > T in the SH3TC2 gene suggestive of Charcot-Marie-Tooth disease type 4C and ichthyosis vulgaris with a novel variant of 2218C > T in the FLG gene. We have reviewed the available literature for reported associations of Charcot-Marie-Tooth disease type 4C and ichthyosis vulgaris. This is probably the first reported association of Charcot-Marie-Tooth disease type 4C and ichthyosis vulgaris with bilateral hearing loss.

Normative Values for Auditory Brainstem Responses and Wave V Thresholds in Indian Neonates and Infants

Click-evoked auditory-brainstem-response (ABR) is widely used for hearing screening in neonates and infants. However, their normative values are based on small studies. This retrospective study was done at a tertiary-care centre where click-ABR based screening is done in all newborns. ABR records (Nihon-Kohden machine, model MEB-9400K) of 420 healthy neonates (preterm 75; full-term 32) and infants (113) done over a period 4 years (2014-2018) were analysed retrospectively. Sick neonates and those with Wave V threshold > 40 dbnHL were excluded. Infants were divided into four groups based on post-conceptual age, Group A (75): 34-36 weeks; Group B (44): 37-40weeks; Group C (188):41 weeks-1 month; and Group D (113): 1-6months. The mean absolute latencies for wave I, wave III, and wave V varied from 1.45-1.56 milliseconds (ms), 4.14-4.37 ms, and 6.36-6.81 ms respectively. Interpeak latencies for I-V and I-III varied from 4.91 ms to 5.22 ms and 2.69 ms to 2.81 ms respectively. Older infants had lower absolute and interpeak latencies. Late preterm babies were not different from term babies suggesting early maturation of brainstem pathways.

Mechanically durable green aerogel composite based on agricultural lignocellulosic residue for organic liquids/oil sorption

Various oil spill cleanup sorbents have good hydrophobicity and oil separation efficiency, but their practical use has been limited due to the difficult and costly fabrication procedure. The research aims towards material development using the consumption of lignocellulosic agricultural residue for isolating cellulose nanofiber and its forward use to construct a 3D porous structure. A simple freeze-drying technique was used to assemble low-density porous structure. The biodegradable polylactic acid coating was used to alter the wettability from hydrophilic to hydrophobic and the maximum water contact angle value was around 120°. The prepared coated samples were testified for a series of oil/organic solvents-water mixtures. The sorption capacity was in the range of 28-70 g/g. The prepared aerogels were efficiently reused for at least 10 cycles. Developed material was used in continuous oil-water separation to remove oil from the water's surface. The cost analysis was estimated for scaleup production in the future.

Isolated psychiatric presentation of cobalamin C type disorder with novel mutation in middle childhood: A case report

A 9-year-old boy presented with abnormal behavior for six months. He had unprovoked aggressive behavior, and occasional self-inflicting behavior. He also had decreased appetite, anhedonia, apathy, reduced sleep, low energy, motivation, and poor interaction with parents and peers. He had mild cognitive impairment, below-average intelligence, moderate depression, and mild psychotic symptoms on assessment with appropriate scales. He had macrocytic anemia with low vitamin B12 levels. Nextgeneration sequencing revealed a novel mutation of Leu116Pro of the MMACHC gene, suggestive of combined methylmalonic aciduria and homocystinuria (cblC type). Timely initiation of therapy can change the long-term neurological outcome.

Lyme Neuroborreliosis with Intracranial Hypertension and Erythema Multiforme: A Rare Presentation

A 9-year-old previously healthy boy presented with high-grade intermittent fever, severe headache associated with neck stiffness for 5 days, rash over trunk and extremities for 4 days, vomiting for 3 days and diplopia for 2 days. There was no history of seizures, abnormal body movements, altered sensorium or focal deficits. On examination, he had maculopapular erythematous rashes over the trunk and extremities and erythema multiforme. He had bilateral abducens nerve palsy and the rest of the cranial nerve, sensory and motor examination was normal. He had neck stiffness and positive Kernig's sign. Fundus examination showed grade 4 papilledema. Cerebrospinal fluid workup revealed elevated opening pressure, lymphocytic pleocytosis, normal protein and glucose levels. Neuroimaging showed features suggestive of intracranial hypertension. Borrelia IgM and IgG antibodies came positive. The uniqueness of our case lies with two rare presenting manifestations of Lyme neuroborreliosis in the same child.

Isolation of cellulose nanocrystals from different waste bio-mass collating their liquid crystal ordering with morphological exploration

Cellulose nanocrystals (CNCs) have been recognized as one of the most promising nanofillers in modern science and technology owing to their outstanding characteristics of renewability, biodegradability, excellent mechanical strength, and liquid crystalline behavior. Interestingly, these properties are dependent on their genetic and also on the isolation process. Therefore, this research aimed to unveil how the biological variations of cellulose can influence on the physical properties of the extracted CNCs. A standard optimized extraction process was adopted to isolate the CNCs from different sources. Extracted CNCs were compared through characterization tools, including Fourier Transformation Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetry Analysis (TGA), Dynamic Light Scattering (DLS), Field Emission Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM), and Polarized Optical Microscopy (POM). Different self-assembly patterns were observed for different CNCs, owing to their biological variations. The resultant nanocrystals displayed variable morphologies such as spherical, rod, and needle shape. The hydrodynamic diameter, crystallinity index, decomposition temperature, liquid crystallinity, and storage modulus were varied. Nanocrystals isolated from non-wood feedstock have shown a higher degree of polymerization of 108.2 and a high Crystllinity Index (C·I.) of 55.1%. The rod-like morphology with the liquid crystalline pattern was obtained at 3 wt% concentration for SCNC.

Bio-extract amalgamated sodium alginate-cellulose nanofibres based 3D-sponges with interpenetrating BioPU coating as potential wound care scaffolds

In this work, sodium alginate (SA) based "all-natural" composite bio-sponges were designed for potential application as wound care scaffold. The composite bio-sponges were developed from the aqueous amalgamation of SA and cellulose nanofibres (CNFs) in bio-extracts like Rice water (Rw) and Giloy extract (Ge). These sponges were modified by employing a simple coating strategy using vegetable oil-based bio-polyurethane (BioPU) to tailor their physicochemical and biological properties so as to match the specific requirements of a wound care scaffold. Bio-sponges with shared interpenetrating polymeric network structures were attained at optimized BioPU coating formulation. The interpenetration of BioPU chains within the sponge construct resulted in the formation of numerous micro-networks in the interconnected microporous structure of sponges (porosity ≥75%). The coated sponge showed a superior mechanical strength (compressive strength ~3.8 MPa, compressive modulus ~35 MPa) with appreciable flexibility and recoverability under repeated compressive loading-unloading cycles. A tunable degradation behaviour was achieved by varying BioPU coating concentrations owing to the different degree of polymer chain entanglement within the sponge construct. The physical entanglement of BioPU chains with core structural components of sponge improved their structural stability by suppressing their full fragmentation in water-based medium without affecting its swelling behaviour (swelling ratio > 1000%). The coated sponge surface has provided a suitable moist-adherent physical environment to support the adhesion and growth of skin cells (HaCaT cells). The MTT (3-(4,5-dimethyl thiazolyl-2)-2,5-diphenyltetrazolium bromide) assay and hemolytic assay revealed the non-toxic and biocompatible nature of coated sponges in vitro. Moreover, no signs of skin erythema or edema were observed during in vivo dermal irritation and corrosion test performed on the skin of Sprague Dawley (SD) rats. Our initial observations revealed the credibility of these sponges as functional wound care scaffolds as well as its diverse potential as a suitable substrate for various tissue engineering applications.

Esterified superhydrophobic nanofibrillated cellulose based aerogel for oil spill treatment

The present work aims towards the structuring of a physically cross-linked aerogels based on nanofibrillated cellulose (NFC) and polyvinyl alcohol (PVA), i.e., NFC/PVA aerogels for oil spillage cleanup. Highly porous (98%) NFC/PVA aerogels having both meso-micro pores were achieved by freeze drying technique. To impart super-hydrophobicity to the composite aerogel, a simple dip coating process was adopted using stearic acid chloride (SAC) solution. The SAC conjugated aerogels combined both superhydrophobic and oleophilic characteristics showed a contact angle of ∼159° and ∼0° with water and oil respectively. FESEM and X-ray microtomography images revealed a self-assembled 3D porous cellular structure of the aerogels. The prepared aerogels were found to be very efficient in separating a series of oil/water mixtures and various organic solvents with excellent selectivity and recyclability. Absorption capacity of the aerogels was at least 35 times higher than their dry weight. Simple mechanical squeezing method was adopted for repetitive uses.

Klippel-Trenaunay and Sturge-Weber overlap syndrome with phakomatosis pigmentovascularis

Klippel–Trenaunay syndrome and Sturge–Weber syndrome are rare disorders with neurologic and cutaneous signs of vascular origin. Phakomatosis pigmentovascularis represents the association of widespread, aberrant, and persistent nevus flammeus and pigmentary abnormalities. We describe a case with features suggestive of overlap between them. A ten-month-old boy presented with seizures, developmental delay, skin lesions on face, trunk and legs, buphthalmos and right lower limb hypertrophy. CT scan of head showed atrophy of brain and calcification. Our case had overlap of Klippel–Trenaunay syndrome and Sturge–Weber syndrome with phakomatosis pigmentovascularis