Thick Vapor Research Articles

Development of breadfruit flour (Artocarpus altilis) with the addition of gelatine as a potential edible film

The potential application of biodegradable films for food applications has gained interest as an alternative to synthetic plastic packaging. Breadfruit is a common starchy fruit in nature and due to its unique and wide availability, it can be good a source for developing biopolymers. This study aimed to develop packaging films made from unripe green breadfruit (Artocarpus altilis) flour with different concentrations of bovine gelatine. The ratios of gelatine and breadfruit flour (G:BF) were 0:5 (G0), 1:5 (G2), 2:5 (G4), 3: 5(G6), 4:5 (G8) and 5:5 (G10). The physical, mechanical and optical properties of these films were investigated. The findings of this study showed that the addition of bovine gelatine in flour solutions had significantly (P<0.05) improved the film thickness, tensile strength (TS), optical properties and water vapour permeability (WVP). Breadfruit film with no gelatine (control) showed the lowest WVP (P<0.05). Based on the Fourier transform infrared spectroscopy (FTIR) spectra, the chemical interaction of hydroxyl group from gelatine and the carboxyl group of breadfruit flour occurred. Therefore, gelatine helped to improve the water barrier and mechanical properties of the BF films as supported by the scanning electron microscopy (SEM) images. Further study to enhance film properties is necessary to apply the material to food products.

Improving the antioxidant ability of gelatin-chitosan film by incorporating an oil-in-water (O/W) Pickering emulsion emulsified by betanin-loaded quaternary ammonium-functionalized mesoporous silica nanoparticles

Active food packaging films with biological activities are a promising food technology, and antioxidant ability is one of the most important biological activities. In this study, an antioxidant active packaging film was prepared by directly blending gelatin, chitosan and a novel O/W Pickering emulsion and then drying. The emulsion was prepared from two antioxidant compounds, Mesona Chinensis essential oils (MCB-EO) and betanin-loaded quaternary ammonium-functionalized mesoporous silica nanoparticles (betanin-QAMSNPs), which provide this emulsion with high antioxidant activity. After adding the emulsion, the water content (26.63 %), water solubility (28.3 %), and water contact angle (86.2°) of the film are lower than those of the gelatin-chitosan film. The thickness and water vapour permeabilities of the betanin-Pickering emulsion film are 275.25 µm and 4.802 × 10−10 g·s−1·m−1·Pa−1, respectively, which are higher than those of gelatin-chitosan films. Adding betanin-Pickering emulsions can decrease the roughness of the surface, which is observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The DPPH and ABTs+ free radical scavenging capacities of the betanin-Pickering emulsion films are 21.77 % and 91.87 %, respectively, which are higher than those of the gelatin-chitosan films (4.64 % and 61.15 %), indicating that adding the betanin-Pickering emulsion can enhance the antioxidant ability of the gelatin-chitosan films. The betanin-Pickering emulsion films can inhibit the oxidation of soybean oil. In conclusion, in this study, a novel food packaging film was successfully prepared and has potential application as an antioxidant food packaging material.

Nano-calcium incorporated piscean collagen scaffolds: potential wound dressing material

BackgroundCollagen proteins extracted from piscean sources are alternatives to bovine and porcine collagen because of their abundance, low price, and skin compatibility and are being explored as suitable wound dressing materials. Intracellular calcium ions are crucial for wound healing, and studies have shown that calcium ion supplementation via an external medium is equally beneficial for speedy recovery. This study explores the wound healing potential of dressing materials that encompass the benefits of nano-calcium and piscean collagen. Nano-calcium sulphate (NCS)-integrated scaffolds were prepared with 100 ppm of NCS and varying concentrations of piscean collagen and HPMC E15 LV. The thickness, tensile strength, folding endurance, pH, expansion profile, and moisture vapour transmission properties of the scaffolds were determined. An in vitro scratch assay and an excision rat wound model were employed to evaluate the wound healing properties of the scaffolds.ResultsThe NCS particles had a mean particle size of 220.7 nm. The scaffolds demonstrated an acceptable thickness, mechanical strength, and flexibility. The scratch assay results revealed that at the end of 24 h of the study, there was an increased wound closure rate with collagen scaffolds in contrast to the control group. In the vivo wound healing studies, formulation CS6 showed 100.0% healing on day 12 as compared to other formulations.ConclusionsWounds treated with scaffolds contracted faster than those treated with a commercial collagen dressing and the control group. The current study thus demonstrates the wound healing ability of nano-calcium sulphate-incorporated piscean collagen scaffolds.

Statistical analysis of textile structures based on conductive yarns

This work presents a series of textile structures fabricated by weaving and knitting using insulating, conductive and antistatic yarns. The physical-mechanical (thickness, water vapour permeability, mass and air permeability), electrical (electrical resistivity), and morphological (SEM, EDAX) properties of the textile structures were analysed to highlight their application potential in interactive products. The statistical analysis of the correlations between physical-mechanical and electric properties was conducted by correlation analysis using the electrical surface resistivity values as dependent variables and the mass (M), thickness (δ) and water vapour permeability (Pv) as independent variable.

Experimental study of a passive thermal management system using vapor chamber for proton exchange membrane fuel cell stack

To mitigate the parasitic power consumption caused by conventional air and water cooling, this study proposes a novel passive cooling scheme that integrates vapor chambers into proton exchange membrane fuel cell stack for thermal management. A 1.32 mm thick vapor chamber is designed and fabricated, and its heat transfer performance is verified through tests conducted at different powers using a heating pad. After confirming that vapor chambers can meet the heat dissipation requirements, the output characteristics of the stack coupled with vapor chambers, are experimentally evaluated during both fast start-up and steady-state operation. Results demonstrate that the vapor chamber efficiently operates at a heat flux density of only 0.052 W/cm2 at evaporation section, while maintaining a maximum in-plane temperature difference of 2.6 °C at 48 W. During fast start-up loading of the stack from 0 A to 40 A, the vapor chamber exhibits rapid thermal response and excellent temperature uniformity, preventing stack performance degradation due to improper operating temperatures. Compared to a general air-cooled stack, the stack coupled with vapor chambers exhibits a significant 21.7% improvement in stack voltage. These results systematically demonstrate the feasibility of vapor chambers for the thermal management of air-cooled proton exchange membrane fuel cell stacks.

Voigt transmission windows in optically thick atomic vapours: a method to create single-peaked line centre filters

Cascading light through two thermal vapour cells has been shown to improve the performance of atomic filters that aim to maximise peak transmission over a minimised bandpass window. In this paper, we explore the atomic physics responsible for the operation of the second cell, which is situated in a transverse (Voigt) magnetic field and opens a narrow transmission window in an optically thick atomic vapour. By assuming transitions with Gaussian line shapes and magnetic fields sufficiently large to access the hyperfine Paschen–Back regime, the window is modelled by resolving the two transitions closest to line centre. We discuss the validity of this model and perform an experiment which demonstrates the evolution of a naturally abundant Rb transmission window as a function of magnetic field. The model results in a significant reduction in two-cell parameter space, which we use to find theoretical optimised cascaded line centre filters for Na, K, Rb and Cs across both D lines. With the exception of Cs, these all have a better figure of merit than comparable single cell filters in literature. Most noteworthy is a Rb-D2 filter which outputs of light through a single peak at line centre, with maximum transmission 0.71 and a width of 330 MHz at half maximum.

Exploring Gas-Liquid Reactions with Microjets: Lessons We Are Learning.

Liquid water is all around us: at the beach, in a cloud, from a faucet, inside a spray tower, covering our lungs. It is fascinating to imagine what happens to a reactive gas molecule as it approaches the surface of water in these examples. Some incoming molecules may first be deflected away after colliding with an evaporating water molecule. Those that do strike surface H2O or other surface species may bounce directly off or become momentarily trapped through hydrogen bonding or other attractive forces. The adsorbed gas molecule can then desorb immediately or instead dissolve, passing through the interfacial region and into the bulk, perhaps diffusing back to the surface and evaporating before reacting. Alternatively, it may react with solute or water molecules in the interfacial or bulk regions, and a reaction intermediate or the final product may then desorb into the gas phase. Building a "blow by blow" picture of these pathways is challenging for vacuum-based techniques because of the high vapor pressure of water. In particular, collisions within the thick vapor cloud created by evaporating molecules just above the surface scramble the trajectories and internal states of the gaseous target molecules, hindering construction of gas-liquid reaction mechanisms at the atomic scale that we strive to map out.The introduction of the microjet in 1988 by Faubel, Schlemmer, and Toennies opened up entirely new possibilities. Their inspired solution seems so simple: narrow the end of a glass tube to a diameter smaller than the mean free path of the vapor molecules and then push the liquid through the tube at speeds of a car on a highway. The narrow liquid stream creates a sparse vapor cloud, with water molecules spaced far enough apart that they and the reactant gases interact, at most, weakly. Experimentalists, however, confront a host of challenges: nozzle clogging, unstable jetting, searching for vacuum-compatible solutions, measuring low signal levels, and teasing out artifacts because the slender jet is the smallest surface in the vacuum chamber. In this Account, we describe lessons that we are learning as we explore gases (DCl, (HCOOH)2, N2O5) reacting with water molecules and solute ions in the near-interfacial region of these fast-flowing aqueous microjets.

Bayesian atmospheric correction over land: Sentinel-2/MSI and Landsat 8/OLI

Abstract. Mitigating the impact of atmospheric effects on optical remote sensing data is critical for monitoring intrinsic land processes and developing Analysis Ready Data (ARD). This work develops an approach to this for the NERC NCEO medium resolution ARD Landsat 8 (L8) and Sentinel 2 (S2) products, called Sensor Invariant Atmospheric Correction (SIAC). The contribution of the work is to phrase and solve that problem within a probabilistic (Bayesian) framework for medium resolution multispectral sensors S2/MSI and L8/OLI and to provide per-pixel uncertainty estimates traceable from assumed top-of-atmosphere (TOA) measurement uncertainty, making progress towards an important aspect of CEOS ARD target requirements. A set of observational and a priori constraints are developed in SIAC to constrain an estimate of coarse resolution (500 m) aerosol optical thickness (AOT) and total column water vapour (TCWV), along with associated uncertainty. This is then used to estimate the medium resolution (10–60 m) surface reflectance and uncertainty, given an assumed uncertainty of 5 % in TOA reflectance. The coarse resolution a priori constraints used are the MODIS MCD43 BRDF/Albedo product, giving a constraint on 500 m surface reflectance, and the Copernicus Atmosphere Monitoring Service (CAMS) operational forecasts of AOT and TCWV, providing estimates of atmospheric state at core 40 km spatial resolution, with an associated 500 m resolution spatial correlation model. The mapping in spatial scale between medium resolution observations and the coarser resolution constraints is achieved using a calibrated effective point spread function for MCD43. Efficient approximations (emulators) to the outputs of the 6S atmospheric radiative transfer code are used to estimate the state parameters in the atmospheric correction stage. SIAC is demonstrated for a set of global S2 and L8 images covering AERONET and RadCalNet sites. AOT retrievals show a very high correlation to AERONET estimates (correlation coefficient around 0.86, RMSE of 0.07 for both sensors), although with a small bias in AOT. TCWV is accurately retrieved from both sensors (correlation coefficient over 0.96, RMSE <0.32 g cm−2). Comparisons with in situ surface reflectance measurements from the RadCalNet network show that SIAC provides accurate estimates of surface reflectance across the entire spectrum, with RMSE mismatches with the reference data between 0.01 and 0.02 in units of reflectance for both S2 and L8. For near-simultaneous S2 and L8 acquisitions, there is a very tight relationship (correlation coefficient over 0.95 for all common bands) between surface reflectance from both sensors, with negligible biases. Uncertainty estimates are assessed through discrepancy analysis and are found to provide viable estimates for AOT and TCWV. For surface reflectance, they give conservative estimates of uncertainty, suggesting that a lower estimate of TOA reflectance uncertainty might be appropriate.

The effect of incorporation of gambier filtrate and rosella flower petals extract on mechanical properties and antioxidant activity of canna starch based active edible film

The research objective was to analyse the incorporation effect of gambier filtrate and rosella flower petals extract on mechanical properties and antioxidant activity of canna starch-based active edible film. This research used an experimental method consisting of two treatments, namely gambier filtrate (A): A1 = 3, A2 = 4, and A3 = 5 (% v/v), as well as rosella flower petals extract (B): B1 = 2, B2 = 4 and B3 = 6 (% v/v) and each treatment was replicated three times. The results showed that the two treatment interactions significantly influenced elongation percentage, water vapour transmission rate, and antioxidant activity. The edible film’s thickness, tensile strength, and water vapour transmission rate were 0.096-0.124 mm, 1.89-3.38 MPa, and 12.99-17.04 g.m-2.d-1, respectively. The edible film contains an antioxidant compound of the strong category with IC50 values of 34.53 to 48.02 ppm. Treatment of A3B2 [gambier filtrate 5% (v/v) and rosella flower petals extract 4% (v)] was the best treatment. This edible film is generally suitable for application as a packaging material for food having high lipid content to inhibit the oxidation process of that food.

Investigating Substrate Loss in MEMS Acoustic Resonators and On-Chip Inductors.

This work studies the influence of substrate loss on the performance of acoustic resonators and on-chip inductors and investigates the effective substrate resistivity of seven commonly used substrates in silicon-based devices. The substrates include X-cut lithium niobate (LiNbO3) film with two different thicknesses (400 nm and 1.6 [Formula: see text]) on high-resistivity Si (HR-Si) and amorphous Si wafers, SiO2 film with two different thicknesses on HR-Si, and bare HR-Si. The effective resistivities of these substrates are extracted using coplanar waveguides (CPWs) over a frequency range from 1 to 40 GHz. Using the effective resistivity approach, the efficiency of two substrate loss reduction techniques-Si wafer removal and amorphous Si-in reducing substrate loss is quantified. Comparison of the extracted substrate resistivities of the suspended and un-suspended dielectric-on-Si structures and comparison of LiNbO3 on HR-Si and amorphous Si are carried out. Substrate loss reduction techniques are more advantageous for a thinner dielectric film and at a lower frequency range due to the higher filling factor of the electric field in the Si wafer. Finally, by comparison of the effective substrate resistivity of SiO2 film on an HR-Si with bare HR-Si, thick plasma-enhanced chemical vapor deposition (PECVD) SiO2 film is found to be a good insulation layer to reduce substrate loss.

Fireball and flame venting comparisons: Test data, CFD simulations, and industry standard prediction

Baker Engineering and Risk Consultants, Inc. (BakerRisk®) has performed vented deflagration testing of congested enclosures over a range of configurations, congestion levels, and fuels. This paper provides a comparison of the measured flame jetting distances to predictions made applying standard methods commonly used to calculate the associated hazard zone. These methods include the National Fire Protection Association Standard on Explosion Protection by Deflagration Venting (NFPA 68 (National Fire Protection Association, 2018, )), the British Standard's Gas Explosion Venting Protective Systems (EN 14994 (British Standard EN 14994, 2007)), and a computational fluid dynamics (CFD) analysis.Nine test series were carried out using BakerRisk's Deflagration Load Generator (DLG) test rig. The DLG is a rectangular steel enclosure measuring 48-feet wide × 24-feet deep × 12-feet tall, yielding a total volume of 13,800 ft3 (391 m3), and is enclosed by three solid steel walls, a roof, and floor. The rig vents through one of the long walls (i.e., 48-foot × 12-foot). The venting face was sealed with a 6-mil (0.15 mm) thick plastic vapor barrier for these tests to allow for the formation of the desired fuel air-mixture throughout the rig. Both slightly hyper-stoichiometric propane and lean hydrogen mixtures have been tested in the DLG. Congestion was provided by an array of vertical cylinders. A range of congestion levels and fill fractions were tested. DLG testing was performed with and without vent panels present.Flame jetting distances from the venting face of the DLG were measured using high-speed video. Flame jetting distances were predicted using the Fireball Dimensions calculation from NFPA 68 and the Flame Effects calculation from EN 14994. Blind (i.e., pre-test) simulations were also performed using the FLACS CFD code (Gexcon, 2014). The flame jetting distance in the CFD simulation was determined as the horizontal distance from the DLG vent to the location where the gas temperature dropped below a specified value; the predicted distance for the fuel concentration to drop below half the lower flammability limit (LFL) was also evaluated to assess jetting distance.

Study on the effect of mist flux on water mist fire extinguishing

A series of combustion experiments were carried out by varying the pressure of water mist and the power of the fire source in order to quantitatively study the fire-extinguishing conditions of water mist. The main characteristics of an oil pool fire under the action of water mist are revealed through the analysis of experimental parameters, and a fire extinguishing model is established. The results showed that the thick flammable vapor layer on the oil surface is the source of water mist-induced flame expansion. Besides that, the splashing of oil droplets is one of the reasons for the flame's enhancement. After simplifying the combustion model, the heat and mass transfer approach was utilized to quantitatively study the water mist flux model for fire suppression. When the thrust ratio of fire versus spray (α) exceeds 5, the plume thrust has a significant impact on the water mist droplet trajectory, and the fire extinguishing fails. In other words, the water mist's cooling action is the primary mechanism for putting out the pool fire. The failure to extinguish the fire was mostly due to the mist flux being insufficient to absorb enough heat from the fuel surface to break the combustion equilibrium conditions.

A phenomenological investigation on near-wall bubble behavior close to CHF in flow boiling

The insight information of subcooled flow boiling is very important for the development of boiling crisis mechanistic model. In this paper, visual experiment is carried out in a vertical square channel with a heating rod with diameter of 9.5 mm. Based on the near-wall bubble behavior captured by a high-speed camera, combined with advanced image post-processing technique developed in-house, the qualitative and quantitative analysis of flow boiling behavior near the heating wall are presented when approaching the CHF (Critical Heat Flux). According to the visual experimental study, a detailed discussion on the phenomena before CHF and during the CHF is presented. With high heat flux, periodic large vapor clot passes with relatively constant frequency. Then periodic wavy vapor layer and liquid film clearly appear in the near-wall region when the working condition is extremely close to the CHF. It is found that high thermal-hydraulic parameters, including system pressure, mass flux and inlet subcooling, prevent the formation of thick vapor layer, and this is a significant precursor to trigger boiling crisis. This implies that the possibility of triggering boiling crisis is reduced due to the difficulty in forming thicker vapor layer, and lead to higher CHF value. Additionally, a prediction of wavelength between two-phase layers is proposed by combining visual observations and instability theory. The predicted results show good agreement compared with experimental data. Those results can provide predictions of key interfacial feature parameters for developing CHF mechanistic model.

Water Vapour Transport in Biopolymeric Materials: Effects of Thickness and Water Vapour Pressure Gradient on Yeast Biomass-Based Films

Water Vapour Transport in Biopolymeric Materials: Effects of Thickness and Water Vapour Pressure Gradient on Yeast Biomass-Based Films

A new ultra-thin vapor chamber with composite wick for thin electronic products

The ever-increasing performance of thin portable electronic products has made their heat dissipation issues more and more severe, or even become failure. A novel 0.5 mm thick ultra-thin vapor chamber (UTVC) with six spiral woven meshes and single-layer mesh acting as the wick is developed for cooling portable electronic products. The heat load capacity of the UTVC could be improved through the mixed effect of the spaced structure and composite wick by both decreasing the pressure drop of vapor flow and the fluid flow. The UTVC is tested in five typical positions, and the results show that it can withstand heating power of 10.5 W, 10 W, 10 W, 10 W, and 9.5 W in gravity, horizontal, side, inverted and antigravity positions, respectively, implying that the influence of position on the heat transfer performance of the proposed UTVC is not significant. The effective thermal conductivity of the vapor chamber in the gravity position reaches about 18,000 W/m·K. Compared to the thermal module without UTVC, the one with UTVC has effectively improved the cooling effect of thin electronics and eliminated the hot spots.

Quality Characteristics of Biodegradable Film Prepared From Duck Feet Gelatin

Biodegradable films containing different concentrations of duck feet gelatin (DFG) (2.0, 2.5, 3.0, and 3.5%) were produced, and their mechanical and physicochemical properties were measured and compared to those of biodegradable films made from commercial bovine gelatin (CBG). Gel strength of DFG (306.96 g) was significantly higher than that of CBG (216.78 g). Elongation at break (EAB), thickness, and water vapour permeability of DFG films significantly increased as the concentration of gelatin increased. Films with DFG concentration of 3.5% had the EAB value 33.00, compare to CBG with EAB value 25.56%. DFG films exhibit significantly lower water solubility compared to CBG films. Water solubility of films with DFG concentration of 3.5% is 32.37%, meanwhile for CBG is 48.74%. Both of the gelatin films prepared from DFG and CBG were transparent, as indicated by the high L*, ranging from 94.64 to 96.01 for DFG and 95.54 to 96.06 for CBG sources. These results indicate that DFG has great potential for future application as a source material for production of gelatin-based biodegradable films.

Two Poems

Two Poems by Shira Stav [Untitled] We lived on the edge of a poisonous swamp black alligators bathed in it every morning the exhaust tubes clamored and at noon we saw the thick vapor, opaque almost, rising and its molten smell reaching our noses, we could do nothing but breathe. And we clad our skins in long fabrics and we smeared our faces with powder and we stretched our lips into a smile and we called our names as if they weren’t foreign to us too and we delivered our faces in round lines and we traded words as if they were ours and over the luminous tablecloth we squashed bull testicles on our tongue without any wonder and the screenshot of the flickering heart rhythmically ticking, by itself, to itself, was screened in front of us on bright walls dazzling in its black halo, lingering, and only the insulting body kept getting wet when it wasn’t well covered, trembling when it was cold, dripping when hot, stinking when it wasn’t washed, getting fat, crumpling. On the Road And I have already stopped searching turning my head after every bearded man and son so that they take me with them and make me soup I pushed afar every mother, every father I fended off friends and distant brothers, I folded their attentive ears, skipped the expectant benches, asking for no substitutes, I have a home. It wobbles everywhere on poles behind me with a hungry voice implores me to enter it and fold my legs, take off my shoes, and sit down. Translations from the Hebrew By Maayan Eitan POETRY Shira Stav is a scholar of Hebrew literature and a poet, translator, and literary critic. She is a senior lecturer in the Department of Hebrew Literature at Ben-Gurion University of the Negev. She has published two collections of poetry. Stav won the 2009 Bernstein Prize for literary criticism, the 2007 Teva Award for young Hebrew poets, and the 2013 Bernstein Prize for poetry. To read a bio of Maayan Eitan, turn to page 64. PHOTO BY SAMUEL SCRIMSHAW / UNSPLASH, SHIRA STAV / PHOTO BY ELYA LANDAU 74 WLT WINTER 2021 ...

Backward fluorescence of optically thick Cs vapor: Experiment and Monte-Carlo simulations

Backward fluorescence of thick atomic vapors exhibits a dip in the spectra at line center and sub-Doppler structures. We present backward fluorescence spectra of cesium vapor when excited around D2 line for densities for which atoms undergo a few collisions before emitting a photon. Changes on dip symmetry relative to line center and of sub-Doppler structures are observed. We perform Monte-Carlo simulations to investigate the influence of collisions between atoms and of radiation trapping on the spectra. Sub-Doppler structures are interpreted as avoided quenching for excited atoms flying parallel to the surface of the cell. We found that collisions broaden the sub-Doppler structures but have little influence on the dip symmetry which is highly affected by radiation trapping. Moreover, radiation trapping is the main contribution to velocity redistribution that reduces sub-Doppler structures for the range of densities investigated.

Localized Probing of Dielectric Breakdown in Multilayer Hexagonal Boron Nitride.

Hexagonal boron nitride (h-BN) has emerged as a promising 2D/layered dielectric owing to its successful integration with graphene and other 2D materials, although a coherent picture of the overall dielectric breakdown mechanism in h-BN is yet to emerge. Here, we have carried out a systematic study using conduction atomic force microscopy to provide insights into the process of defect generation and dielectric degradation in the progressive breakdown (PBD) and hard breakdown (HBD) stages in 2-5 nm thick chemical vapor deposition (CVD)-grown multilayer h-BN films. The PBD and HBD regimes show different behaviors. Under electrical stress in the PBD stage, defects are generated progressively in the h-BN, leading to a gradual reduction of the effective barrier resistance and continuous soft breakdowns (SBDs) of the dielectric material. Random telegraph noise nano-spectroscopy shows that low frequency noise becomes dominant after an SBD event due to the creation of additional defects around the percolation path. We also observe a wide variation in the current-voltage (I-V) breakdown plots in the PBD stage, giving rise to non-Weibull statistical distribution of the breakdown voltage. We attribute this observation to the significant thickness inhomogeneity in the CVD films. At HBD, h-BN materials are always physically removed from the film, leading to the formation of pits at the breakdown location. Interestingly, pit formation is also occasionally observed in the PBD stage under very low current compliances, suggesting that breakdown may proceed by a mixture of defect generation and material removal in h-BN CVD films.

Effect of pH on functional, gas sensing and antimicrobial properties of bio-nanocomposite gelatin film for food packaging application.

A bio-nanocomposite film is a polymer blend with nanofiller dispersed in a biopolymer matrix. The aim of this study is to investigate the functional, gas sensing and antimicrobial properties of bio-nanocomposite films incorporated with chicken skin gelatin/ tapioca starch/zinc oxide at different pH levels (pH 4, 6, 7 and 8). Bio-nanocomposite films were prepared using a casting technique followed by the characterization of their functional, gas sensing and antimicrobial properties. Film formulations with pH at different levels showed increased thickness, colour and water vapour permeability (WVP) (p < 0.05). In addition, the increase of pH in films in chicken skin gelatin bio-nanocomposite films increased the tensile strength (TS), while decreasing the elongation at break (EAB). The highest response for ammonia gas in chicken skin gelatin bio-nanocomposite films was obtained at pH7, with quick response time (τres) within 10s. The inhibition zone of Staphylococcus aureus in chicken skin gelatin bio-nanocomposite films increased with increasing pH levels. Overall, chicken skin gelatin bio-nanocomposite films with a pH level of 8 were found to have the optimal formulation, with the highest values in thickness, and TS, with the lowest values for WVP and EAB. In conclusion, bio-nanocomposite chicken skin gelatin films with an alkaline pH are a superior packaging material.