Lignin - A green material for antibacterial application - A review.

Lignin's antibacterial properties have become increasingly relevant due to the rise of microbial infectious diseases and antibiotic resistance. Lignin is capable of interacting electrostatically with bacteria and contains polyphenols that cause damage to their cell walls. These features make lignin a desirable material to exhibit antibacterial behavior. Therefore, lignin in antibacterial applications offers a novel approach to address the growing need for sustainable and effective antibacterial materials. Recent research has explored the incorporation of lignin in various biomedical applications, such as wound dressings, implants, and drug delivery systems, highlighting their potential as a sustainable alternative to synthetic antibacterial agents. Furthermore, the development of lignin-based nanomaterials with enhanced antimicrobial activity is an active area of research that holds great promise for the future. In this review, we have provided a summary of how lignin can be incorporated into different forms, such as composite and non-composite synthesis of antibacterial agents and their performances. The challenges and future considerations are also discussed in this review article.

Physical and mechanical properties of Albizia procera glulam beam.

This research was done to evaluate the feasibility of using Albizia procera for manufacturing glulam beams. The physical and mechanical properties of the A. procera glulam beam were evaluated, and these properties were compared to those of the solid A. procera solid timber. The A. procera glulam beam's physical and mechanical properties were all superior to solid A. procera timber. In comparison to A. procera solid timber, A. procera glulam's density, water absorption (WA), linear expansion (LE), and thickness swelling (TS) all improved by 11.1, 48.4, 44.6, and 37.0%, respectively. Again, compared to A. procera solid timber, the modulus of rupture (MOR) and modulus of elasticity (MOE) of the A. procera glulam beam increased by 27.6 and 29.2%, respectively. Additionally, the ASTM specifications were met by the A. procera glulam beam. As a result, based on the properties, it is possible to make A. procera glulam beams as structural timber products.

Probing Single-molecule Interfacial Electron Transfer Inside a Single Lipid Vesicle.

Inhomogeneity in single molecule electron transfer at the surface of lipid in a single vesicle has been explored by single molecule spectroscopic technique. In our study we took Di-methyl aniline (DMA), as the electron donor (D) and three different organic dyes as acceptor. These dyes are C153, C480 and C152 and they reside in different regions in the vesicle depending upon their preference of residence. For each probe, we found fluctuations in the single-molecule fluorescence decay, which are attributed to the variation in the reactivity of interfacial electron transfer. We found a non-exponential auto-correlation fluctuation of the intensity of the probe, which is ascribed to the kinetic disorder in the rate of electron transfer. We have also shown the power law distribution of the dark state (off time), which obeys the levy's statistics. We found a shift in lifetime distribution for the probe (C153) from 3.9 ns to 3.5 ns. This observed quenching is due to the dynamic electron transfer. We observed the kinetic disorderness in the electron transfer reaction for each dye. This source of fluctuation in electron transfer rate may be ascribed to the inherent fluctuation, occurring on the time scale of ~ 1.1 ms (for C153) of the vesicle, containing lipids.

Cellulose-based bionanocomposites in energy storage applications-A review.

The growing demand for energy and environmental issues are the main concern for the sustainable development of modern society. Replacing toxic and expensive materials with inexpensive and biodegradable biomaterials is the main challenge for researchers. Nanocomposites are of the utmost consideration for their application in energy storage devices because of their specific electrochemical properties. Cellulose-based bionanocomposites have added a new dimension to this field since these are developed from available renewable biomaterials. Studies on developing electrodes, separators, collectors, and electrolytes for the batteries have been conducted based on these composites rigorously. Electrodes and separators made of these composites for the supercapacitors have also been investigated. Researchers have used a wide range of micro- and nano-structural cellulose along with nanostructured inorganic materials to produce cellulose-based bionanocomposites for energy devices, i.e., supercapacitors and batteries. The presence of cellulosic materials enhances the loading capacity of active materials and uniform porous structure in the electrode matrix. Thus, it has shown improved electrochemical properties. Therefore, these can help to develop biodegradable, lightweight, malleable, and strong energy storage devices. In this review article, the manufacturing process, properties, applications, and possible opportunities of cellulose-based bionanocomposites in energy storage devices have been emphasized. Its challenges and opportunities have also been discussed.

Effect of Age and Height on the Chemical Properties of Muli Bamboo (Melocanna baccifera).

Melocanna baccifera is the most common bamboo species which grows naturally and gregariously covering large tracts of land in the forests of Chittagong Hill Tracts of Bangladesh. However, there is limited information about the chemical characterization of its culms for its utilization and processing. This paper aimed to determine the effect of age and height position on the chemical properties of M. baccifera. The highest value of holocellulose content was 74.66% for the top portion of 3-year-old bamboo, while the bottom part of 3-year-old bamboo showed the highest value of lignin (27.83%) and extractive (5.24%) content. For caustic soda (1% NaOH) solubility, the bottom portion of 1-year-old bamboo had shown the maximum value (25.67%), and it was the lowest (19.10%) for the top portion of 3-year-old bamboo. Ageing had a significant (p < 0.05) effect on all chemical properties, while the height position had a significant effect on the holocellulose and lignin content and water solubility. The chemical properties of M. baccifera can enable its proper utilization in the downstream process.

Investigating the drying characteristics of Anthocephalus chinensis (Lam.) A. Rich ex Walp wood.

Anthocephalus chinensis (Lam.) A. Rich ex Walp is widely used as raw materials in particleboard and match industries in Bangladesh. The current study aimed to identify the drying characteristics of A. Chinensis wood for succeeding industrial usages. A compartment kiln dryer (heat and vent dryer) was used in this study. The drying characteristics and drying quality of A. Chinensis wood were measured. The boards reached 6-10% moisture content in 13 days from their green condition. The total proportions of the check, twist, and collapse in boards were 22.5, 32.5, and 7.3%, respectively. The volumetric shrinkage was 21.67%. Based on this study, further study may help to develop a complete drying schedule of A. Chinensis wood with fewer drying defects for application at industrial level.

Formulation and Characterization of Formaldehyde-Free Chemically Modified Bone-Based Adhesive for Lignocellulosic Composite Products.

This study investigates the efficacy of chemically modified bone adhesive as a formaldehyde-free binder for wood-based industries. Two different types of adhesive are formulated after chemical modification of bone powder using sulfuric acid (0.5 m) and polyvinyl acetate (PVA). Gel time, solid content, Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), viscosity, and single lap joint test for shear strength are analyzed in order to assess the adhesive properties. To analyze the efficacy of the formulated adhesive, particleboards are fabricated using boiled and unboiled sugarcane bagasse. The physical and mechanical properties of the fabricated panels are measured following ASTM standards. It is found that adhesive Type C (T-C) has the shortest gel time of 4.2 min for the highest shear strength, i.e., 5.31 MPa. The particleboard (BTC-2) fabricated using T-C adhesive shows a highest density of 0.73 g cm-3, a modulus of elasticity (MOE) of 1975 N mm-2, and a modulus of rupture (MOR) of 11.80 N mm-2. The dimensional stability of the fabricated particleboards does not follow the standard requirements; however, further study might be helpful for using the chemically modified bone adhesive as a biobased adhesive.

Preparation and Evaluation of Rice Bran-Modified Urea Formaldehyde as Environmental Friendly Wood Adhesive.

In this study, defatted rice bran (RB) is used to prepare an environmentally friendly adhesive through chemical modifications. The RB is mixed with distilled water with ratios of 1:5 and 1:4 to prepare Type A and Type B adhesives, respectively having pH of 6, 8 and 10. Type A adhesive is prepared by treating RB with 1% potassium permanganate and 4% poly(vinyl alcohol), whereas Type B is formulated by adding 17.3% formaldehyde and 5.7% urea to RB. Viscosity, gel time, solid content, shear strength, Fourier transform infrared (FTIR) spectroscopy is carried out, and glass transition temperature (T g), and activation energy (E a) are determined to evaluate the performance of the adhesives. E a data reveal that adhesives prepared at mild alkaline (pH 8) form long-chain polymers. Gel time is higher in the fabricated adhesives than that of the commercial urea formaldehyde (UF). FTIR data suggest that functional groups of the raw RB are chemically modified, which enhances the bondability of the adhesives. Shear strength data indicates that bonding strength increases with increasing pH. Similar results are also observed for physical and mechanical properties of fabricated particleboards with the adhesives. The results demonstrate that RB-based adhesives can be used as a potential alternative to currently used UF-based resin.

Water hyacinth (Eichhornia crassipes (Mart.) Solms.) as an alternative raw material for the production of bio-compost and handmade paper.

Water hyacinth (WH) is considered as the worst aquatic weed in the world because of its rapid growth and fast spread into new areas of fresh water bodies. We investigated the potentiality of using WH as a raw material for production of handmade paper and compost in Bangladesh. Potash pulping was done using potassium hydroxide (KOH) at different alkali concentrations (8-12%) with a liquor to solid ratio of 7:1 at 145 °C for 2 h. The pulp was bleached using hydrogen peroxide (H2O2), and pulp properties (brightness, tear index and tensile index) of bleached and unbleached pulps were analyzed following the respective TAPPI standards. The produced black liquor was mixed with WH along with kitchen bio-wastes to produce compost. The properties of the compost were tested following the published protocols, i.e., wet digestion, Kjeldahl, vanadomolybdophosphoric acid, and Flame Spectrophotometry methods. Brightness, tensile index and tear index of bleached hand sheets were found to be 37.2%, 49.2 N m/g and 6.79 m.Nm2/g, respectively suggesting significant contribution of bleaching on WH paper quality. Addition of black liquor significantly increased the nitrogen and potassium content of bio-waste compost. Thus, WH can be used as a raw material for making handmade paper while the process by-product can be supplemented to improve the nutritional quality of compost. Such cottage-industry fabrication of WH green products could be developed to control the infestation of WH in water bodies, and this technology may provide for new possible sustainable livelihood option.

COVID-19 and municipal solid waste (MSW) management: a review.

Municipal solid waste (MSW) represents an inevitable by-product of human activity and a major crisis for communities across the globe. In recent times, the recycling of MSW has drawn attention as the process can add value through resources from the recovered waste materials and facilitates the process of circular economy. However, during the unprecedented coronavirus (COVID-19) outbreak, the risk of infection with the highly contagious virus has proven detrimental to the continuation of MSW as a valuable resource. The volume of waste, especially household waste, is higher; face masks, PPE (personal protective equipment), and hazardous materials such as batteries and empty chlorine bottles are examples of extra waste that have arisen during the pandemic. Various countries have set up initiatives for MSW management, including safety measurements for employees in the MSW management sector. The use of disinfectant prior to sorting waste, as well as storing waste for 9 days, may help to inactivate the COVID-19 virus, ensuring an appropriate safety level for MSW management. This work aimed at studying different MSW management strategies, specific challenges, and possible solutions for better understanding for those involved in waste management, in addition to providing a possible management strategy during and post-COVID-19 pandemic.

COVID-19 pandemic and healthcare solid waste management strategy - A mini-review.

Healthcare waste comprises the waste generated by healthcare facilities, medical laboratories and biomedical research facilities. Improper treatment of this waste poses serious risks of disease transmission to waste pickers, waste workers, health workers, patients, and the community in general through exposure to infectious agents. Poor management of the waste emits harmful and deleterious contaminants into society. However, contamination of highly contagious agents such as the COVID-19 virus has created enormous instability in healthcare waste handling and subsequent recycling because of the volume of the waste generated and its contagious nature. Several countries have adopted safety measures to combat this contamination and manage healthcare waste; however, these measures are insufficient and vary depending on the context of the country. In addition, the WHO has set out guidelines for management of healthcare waste. These guidelines are helping to manage the highly contagious healthcare waste resulting from the current pandemic. Proper healthcare waste management may add value by reducing the spread of the COVID-19 virus and increasing the recyclability of materials instead of sending them to landfill. Disinfecting and sorting out healthcare waste facilitates sustainable management and allows their utilization for valuable purposes. This review discusses the different healthcare solid waste management strategies practiced in different countries, the challenges faced during this management, and the possible solutions for overcoming these challenges. It also provides useful insights into healthcare solid waste management scenarios during the COVID-19 pandemic and a possible way forward.

Raw natural rubber latex-based bio-adhesive for the production of particleboard: formulation and optimization of process parameters.

In this study, bio-adhesives from natural rubber latex (NRL) were combined with starch and formic acid to fabricate jute stick-based particleboards (JSPs). Different blends of NRL, starch, and formic acid, i.e., 6 : 1 : 1, 2 : 1 : 1, and 2 : 3 : 3, were used to produce particleboards using a pressing temperature of 180 °C and applied pressure of 5 MPa using a 5 min pressing time. The particleboards were tested for physical, mechanical, and thermal properties according to ANSI standards. Based on initial screening, the best formula (NRL/starch/formic acid of 2 : 3 : 3) was used to optimize the temperature and pressing time for the highest board performance. The highest density, tensile strength, modulus of elasticity, and modulus of rupture were 830 g cm-3, 10.51, 2380, and 20.05 N mm-2, respectively. Thermo-gravimetric analysis indicated that thermal decomposition of samples primarily occurred in a temperature range of 265 to 399 °C, indicating good thermal performance. The measured physical and mechanical properties of the produced JSPs fulfilled the production standards. However, fulfilling the water absorption and thickness swelling criteria was a challenge. The results indicate that NRL is a promising alternative binder when blended with starch and formic acid.

Surface and Interface Engineering for Nanocellulosic Advanced Materials.

How do trees support their upright massive bodies? The support comes from the incredibly strong and stiff, and highly crystalline nanoscale fibrils of extended cellulose chains, called cellulose nanofibers. Cellulose nanofibers and their crystalline parts-cellulose nanocrystals, collectively nanocelluloses, are therefore the recent hot materials to incorporate in man-made sustainable, environmentally sound, and mechanically strong materials. Nanocelluloses are generally obtained through a top-down process, during or after which the original surface chemistry and interface interactions can be dramatically changed. Therefore, surface and interface engineering are extremely important when nanocellulosic materials with a bottom-up process are fabricated. Herein, the main focus is on promising chemical modification and nonmodification approaches, aiming to prospect this hot topic from novel aspects, including nanocellulose-, chemistry-, and process-oriented surface and interface engineering for advanced nanocellulosic materials. The reinforcement of nanocelluloses in some functional materials, such as structural materials, films, filaments, aerogels, and foams, is discussed, relating to tailored surface and/or interface engineering. Although some of the nanocellulosic products have already reached the industrial arena, it is hoped that more and more nanocellulose-based products will become available in everyday life in the next few years.

An Efficient Synthesis Strategy for Metal-Organic Frameworks: Dry-Gel Synthesis of MOF-74 Framework with High Yield and Improved Performance.

Vapor-assisted dry-gel synthesis of the metal-organic framework-74 (MOF-74) structure, specifically Ni-MOF-74 produced from synthetic precursors using an organic-water hybrid solvent system, showed a very high yield (>90% with respect to 2,5-dihydroxyterepthalic acid) and enhanced performance. The Ni-MOF-74 obtained showed improved sorption characteristics towards CO2 and the refrigerant fluorocarbon dichlorodifluoromethane. Unlike conventional synthesis, which takes 72 hours using the tetrahydrofuran-water system, this kinetic study showed that Ni-MOF-74 forms within 12 hours under dry-gel conditions with similar performance characteristics, and exhibits its best performance characteristics even after 24 hours of heating. In the dry-gel conversion method, the physical separation of the solvent and precursor mixture allows for recycling of the solvent. We demonstrated efficient solvent recycling (up to three times) that resulted in significant cost benefits. The scaled-up manufacturing cost of Ni-MOF-74 synthesized via our dry-gel method is 45% of conventional synthesis cost. Thus, for bulk production of the MOFs, the proposed vapor-assisted, dry-gel method is efficient, simple, and inexpensive when compared to the conventional synthesis method.

Quality evaluation of dissolving pulp fabricated from banana plant stem and its potential for biorefinery.

The study was conducted to evaluate the quality of dissolving pulp of Musa sapientum L. (banana) plant stem and its potential for biorefinery. Introduction of pre-hydrolysis prior to any alkaline pulping process helps to reduce the content of hemicellulose and consequently produce acceptably high content of cellulose pulp. Water pre-hydrolysis was done at 150°C for 90min. The amount of lignin, xylan and glucan in the extracted pre-hydrolysis liquor (PHL) was 1.6, 4.9 and 1.6%, respectively. Pulping of pre-extracted chips was done following soda-AQ, alkaline sulfite and kraft process. The ratio of chip to liquor was 1:7 for both pre-hydrolysis and pulping. The kraft pulping process with 20% active alkali and 25% sulfidity at 150°C for 90min showed the best result. The lowest kappa number was 26.2 with a considerable pulp yield of 32.7%. The pulp was bleached by acidic NaClO2 and the consistency was 10% based on air-dried pulp. The lowest amount of 7% NaClO2 was used for the bleaching sequence of D0ED1ED2. After D0ED1ED2 bleaching, the pulp showed that α-cellulose, brightness and ash were 91.9, 77.9 and 1.6% respectively. The viscosity was 19.9cP. Hence, there is a possibility to use banana plant stem as a raw material for dissolving grade pulp and other bioproducts.

Solvation dynamics of biological water in a single live cell under a confocal microscope.

Time-resolved confocal microscopy has been applied to study the cytoplasm and nucleus region of a single live Chinese hamster ovary (CHO) cell. To select the cytoplasm and the nucleus region, two different fluorescent probes are used. A hydrophobic fluorescent dye, DCM, localizes preferentially in the cytoplasm region of a CHO cell. A DNA binding dye, DAPI, is found to be inside the nucleus of the cell. The locations of the probes are clearly seen in the image. Emission maxima of the dyes (DCM in cytoplasm and DAPI in the nucleus) are compared to those of the same dyes in different solvents. From this, it is concluded that the polarity (dielectric constant, ε) of the microenvironment of DCM in the cytoplasm is ~15. The nucleus is found to be much more polar with ε ≈ 60 (as reported by DAPI). The diffusion coefficient (and hence viscosity) in the cytoplasm and the nucleus was determined using fluorescence correlation spectroscopy (FCS). The diffusion coefficient (D(t)) of the dye (DCM) in the cytoplasm is 2 µm(2) s(-1) and is ~150 times slower than that in bulk water (buffer). D(t) of DAPI in the nucleus (15 µm(2) s(-1)) is 30 times slower than that in bulk water (buffer). The extremely slow diffusion inside the cell has been ascribed to higher viscosity and also to the binding of the probes (DCM and DAPI) to large biological macromolecules. The solvation dynamics of water in the cytoplasm (monitored by DCM) exhibits an average relaxation time [τ(sol)] of 1250 ± 50 ps, which is about 1000 times slower than in bulk water (1 ps). The solvation dynamics inside the nucleus (studied using DAPI) is about 2-fold faster, [τ(sol)] ≈ 775 ps. The higher polarity, faster diffusion, and faster solvation dynamics in the nucleus indicates that it is less crowded and less restricted than the cytoplasm.

Effect of NaCl on ESPT-mediated FRET in a CTAC micelle: a femtosecond and FCS study.

Femtosecond upconversion, single-molecule fluorescence resonance energy transfer (sm-FRET) and fluorescence correlation spectroscopy (FCS) are applied to study the competition between excited-state proton transfer (ESPT) and FRET [to rhodamine 6G (R6G)] of 8-hydroxypyranine-1,3,6-trisulfonate (HPTS) in cetyltrimethylammonium chloride (CTAC) micelles. Pyranine exhibits dual emission at λ(em)=430 nm for ROH and 520 nm for RO(-). The absorption spectrum of R6G (acceptor) has very good overlap with the RO(-) emission and poor overlap with ROH emission. It is observed that FRET occurs readily from the RO(-)* state of HPTS (donor) to R6G (acceptor). Multiple timescales of FRET were detected from the rise time of acceptor emission. The different timescales correspond to different donor-acceptor distances. The ultrafast components (8.5 and 13 ps) are assigned to FRET at a close contact of donor and acceptor (≈20 Å). The longer components (500 and 800 ps) arise from long-distance FRET from the donor to the acceptor (≈40 Å) located in different regions of the CTAC micelle. The larger donor-acceptor distances agree with those obtained from an sm-FRET study. On addition of 4 M NaCl to CTAC, the rate of proton transfer (k(PT)) slowed by about eight and two times, respectively, for the fast and slow sites of the CTAC micelle. As a result, the intensity of the ROH emission increases and that of RO(-) decreases. The decrease in the intensity of the RO(-) emission causes a decrease in the efficiency of FRET.

Diffusion of organic dyes in a niosome immobilized on a glass surface using fluorescence correlation spectroscopy.

Giant multilameller niosomes containing cholesterol and triton X-100 are studied using fluorescence correlation spectroscopy (FCS). Dynamic light scattering (DLS) data indicates formation of niosomes of broadly two different sizes (diameter)--~150 nm and ~1300 nm. This is confirmed by field emission scanning electron microscopy (FE-SEM) and confocal microscopy. The diffusion coefficient (D(t)) of three organic dyes in the niosome immobilized on a glass surface is studied using fluorescence correlation spectroscopy. On addition of the room temperature ionic liquids (RTIL) (1-methyl-3-pentylimidazolium bromide, [pmim][Br] and 1-methyl- 3-pentylimidazolium tetra-fluoroborate, [pmim][BF(4)]) the size of the niosome particles increases. The D(t) of all the organic dyes (DCM, C343 and C480) increases on addition of RTILs, indicating faster diffusion. The viscosity calculated from the D(t) of the three dyes exhibits weak probe dependence. Unlike lipid or catanionic vesicle, the D(t) values in a niosome exhibit very narrow distribution. This indicates that the niosomes are fairly homogeneous with small variation of viscosity.

UV-vis-NIR and EPR characterisation of the redox series [MQ(3)](2+,+,0,-,2-), M = Ru or Os, and Q = o-quinone derivative.

The neutral title compounds with Q = 3,5-di-tert-butyl-o-quinone or 4,6-di-tert-butyl-N-phenyl-o-iminobenzoquinone (Q(x)) were studied by UV-vis-NIR spectroelectrochemistry and by EPR spectroscopy in the case of the odd-electron monocation and monoanion intermediates. Supported by DFT and TD-DFT calculations, the results indicate stepwise electron removal from predominantly ligand-based delocalised MOs on oxidation whereas the stepwise electron uptake on reduction involves unoccupied MOs with considerably metal-ligand mixed character. In both cases, the strong near-infrared absorption of the neutral precursors diminishes. In comparison to the ruthenium series, the osmium analogues exhibit larger transition energies from enhanced MO splitting and a different EPR response due to the higher spin-orbit coupling. The main difference between the quinone (1(n), 2(n)) and corresponding monoiminoquinone systems (3(n), 4(n)) is the shift of about 0.6 V to lower potentials for the monoimino analogues. While the absorption features do not differ markedly, the EPR data reflect a higher degree of covalent bonding for the complexes with monoimino ligands.

Salt effect on the ultrafast proton transfer in niosome.

Excited state proton transfer (ESPT) of pyranine (8-hydroxypyranine-1,3,6-trisulfonate, HPTS) in a niosome is studied by fluorescence correlation spectroscopy (FCS) and femtosecond up-conversion. The niosome consists of a neutral surfactant triton X-100 (TX-100) and cholesterol. FCS studies suggest that in the presence of niosome almost all of the HPTS is transferred to the niosome and the amount of free HPTS present in bulk water is negligible. The time constant of initial proton transfer (τ(PT)) in niosome (40 ps) is ∼8 times slower than that (5 ps) in bulk water, while the time constants of recombination (τ(rec)) and dissociation (τ(diss)) are ∼4 times and ∼1.5 times slower in niosome, respectively. On addition of NaCl, the rate of ESPT is markedly retarded both in free water and in niosome. In the niosome, τ(PT) slows down to 80 ps in 1 M NaCl and 225 ps in 4 M NaCl.