Non-porous Surfaces Research Articles

Methane decomposition kinetics on unfunctionalized alumina surfaces

The pyrolytic conversion of methane for the production of hydrogen and carbon was investigated over nonporous α-Al2O3 surfaces in the range of 900–1300 °C. Two devices were used: i) a single particle reactor to determine the carbon deposition rate at various temperatures and ii) a fixed bed in which both methane conversion and carbon deposition were measured.It was observed that at 1000 °C and below, the selectivity towards carbon (and hydrogen) was initially low over fresh α-Al2O3 (e.g. 38% at 250 s reaction time), increasing to 100% over time. Methane conversion was constant at 20% during this period. These observations point towards the presence of an activation process for the formation of carbon and hydrogen from the intermediates products (e.g. benzene) of methane pyrolysis. A temperature dependent maximum in carbon loading was observed. When this maximum carbon loading was reached, methane conversion also stopped completely, indicating 100% selectivity towards carbon and hydrogen.Two kinetic models for carbon deposition were derived and applied. After parameterization of these models using single particle data, they were able to predict carbon growth and CH4 conversion as function of temperature, specific bed area, carbon loading and gas composition in the new data set from the fixed bed.

Ultrahigh stable lead halide perovskite nanocrystals as bright fluorescent label for the visualization of latent fingerprints

Fingerprints formed by the raised papillary ridges are one of the most important markers for individual identification. However, the current visualization methods for latent fingerprints (LFPs) suffer from poor resolution, low contrast, and high toxicity. In this work, the CsPbBr3/Cs4PbBr6 nanostructured composite crystal (CsPbBr3/Cs4PbBr6 NCC) were synthesized via a simple chemical solvent-assisted method. Compared with conventional perovskites, the as-prepared CsPbBr3/Cs4PbBr6 NCC present an outstanding long-term environmental and water stability with 42% and 80% photoluminescence intensity remaining after 28 d under water and air conditions, respectively. Moreover, a special response to biomolecules from fingerprints was observed due to the hydrophobic interactions between the CsPbBr3/Cs4PbBr6 NCC surface hydrophobic ligands (oleyl amine and oleic acid) and the hydrophobic groups in the biomolecules from the human fingers. Clear LFPs images were visualized in a bright environment illuminating the prepared CsPbBr3/Cs4PbBr6 NCC powder under UV light of wavelength 365 nm. The images were also obtained on porous and non-porous surfaces such as metal, plastic, wood, glass, and paper products. These perovskite nanocrystals are expected a stable and bright luminescent labeling agent for LFPs visualization and have potential application in crime scene and personal identifications.

"Touch DNA Collection Techniques for Non-Porous Surfaces Using Cotton and Nylon Swabs"

Touch DNA, commonly known as trace DNA, is widely used in forensic DNA casework. However, touch DNA samples are challenging because of the many variables that can impact the success of obtaining a good quality usable DNA profile. Cotton and nylon flocked swabs are often used to collect touch DNA from surfaces, so this study aimed to test different techniques using cotton (150C) and nylon flocked (4N6FLOQSwabs®) swabs to collect touch DNA from non-porous surfaces. There was a significant difference amongst the three recovery techniques tested to recover touch DNA with cotton swabs and nylon swabs from textured plastic (p < 0.001), with a nylon swab and 30μl of distilled water being more efficient than a cotton swab with 100μl of distilled water. There was also a significant difference between the four recovery techniques to recover touch DNA from glass surfaces exposed to high humidity and low temperature (5 °C/78%) (p <0.001), with a dry cotton or nylon swab being allowing more efficient recovery of touch DNA from non-porous humid surfaces such as glass.

Comparison of general cyanoacrylate and Sirchie cyanoacrylate for latent fingerprint on non-porous surfaces by cyanosafe fuming chamber with Airsafe controller

Comparison of general cyanoacrylate and Sirchie cyanoacrylate for latent fingerprint on non-porous surfaces by cyanosafe fuming chamber with Airsafe controller

Antiviral Activity of a Continuously Active Disinfectant Against the Human Coronavirus 229E

BackgroundBackground: Contaminated hospital room environmental surfaces and noncritical medical devices are a potential source of transmission of healthcare pathogens including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Technologies that provide continuous decontamination between episodes of manual cleaning and disinfection could reduce the risk for transmission of SARS-CoV-2 from surfaces in rooms of coronavirus disease (COVID-19) patients. The aim of this study was to evaluate a continuously active disinfectant (CAD) that is registered by the Environmental Protection Agency (EPA) to kill microbes (including viruses) on surfaces for >24 hours.MethodsMethods: We investigated the CAD against the human coronavirus, 229E, using the EPA “Protocol for Residual Self-Sanitizing Activity of Dried Chemical Residuals on Hard, Non-Porous Surfaces”. The method simulates contact and touches by incorporating “wear” of the test surface as well as re-inoculations of the test and control surfaces over at least 24 hours. The test surfaces were inoculated with ≥5-log10 per carrier, treated with the novel disinfectant, allowed to dry, and then abraded using a standardized abrasion machine under multiple alternating wet and dry wiping conditions (6 dry cycles, 6 wet cycles, total 12 cycles [2 passes per cycle=24 passes] each 24 hours) interspersed with 6 re-inoculations (or 12 re-inoculations in 48 hours) with ≥3.75-log10 of the test pathogen. After 24 or 48 hours, the surface was reinoculated with ≥5-log10 a final time, and the ability of the CAD to kill >99.9% of 229E with 1- or 5-minute contact times was measured on glass.ResultsResults: The CAD studied demonstrated excellent sustained antiviral activity (>4.0-log10 reduction) against 229E with 1- and 5-minute contact times after 24 and 48 hours.ConclusionsConclusion: Based on our data using 229E, CAD may reduce or eliminate the role of contaminated environmental surfaces and noncritical equipment in transmission of SARS-CoV-2.

Physicochemical and Functional Properties of Starches from Pachyrhizus erosus with Low Digestibility

The search for novel natural ingredients has been stimulated by the food and non-food industries, and roots of Pachyrhizus erosus (jicama) emerges as promising crops for industrial production due to its crispy and succulent flesh and high yield. Therefore, jicama starches from Fujian Province (SFJ) and Guangxi Province (SGX) were isolated and the microstructure, swelling power, crystallinity, thermal property, rheological property, and in vitro digestibility were determined. The starch granules of SFJ and SGX showed polyhedral, spherical or semi-spherical shapes with smooth nonporous surface. SFJ and SGX showed increasing solubility and swelling power with the increasing of temperature. By X-ray diffraction analysis, both had typical A-type crystallinity, but SFJ showed lower relative crystallinity (29.4%) than SGX (35.4%). SFJ with smaller granule sizes and lower relative crystallinity showed weaker thermal stability, lower viscosity, weaker strength of starch gels, and lower Resistant Starch (RS) content. The high contents of RS in SFJ (65.67%) and SGX (70.37%) suggested that jicama is promising low energy food for special purposes.

Development of Latent Fingerprints on Non-Porous Surface with Fluorescent Dye Based Small Particle Reagent

Fingerprints are a useful source of evidence in establishing the identity of the person and hold large importance in crime scene investigations. A diverse range of physical and chemical methods are available for the development of latent fingerprints, but limited work is done on detection of prints from wet non-porous surfaces. The study aimed at developing a novel method for identification of latent fingerprints from such a type of surface. Small Particle Reagent was prepared using non-toxic chemicals and was proven to be effective in detecting latent fingerprints on Aluminum Foil. Fluorescent component, Basic Yellow-40 dye was used in the formulation. The Shelf life of the SPR solution was also considered an important factor in the study and was found to be 25 days.

Testing the effectiveness of Lumicyano™ with CYANO-SHOT™ components: A novel HEAT solution

Cyanoacrylate fuming is a process by which latent prints are visualized on non-porous surfaces (Yamashita and French, 2011). Following the polymerization of cyanoacrylate molecules on top of a latent print, RAM, a fluorescent dye stain, is applied to further visualize the print with a forensic light source (Yamashita and French, 2011). There are situations in which the FBI’s Hazardous Evidence Analysis Team (HEAT) is prohibited from using adequate amounts of RAM, thereby establishing a need to find an effective substitute. This study tested the efficacy of using Lumicyano™ products in conjunction with the CYANO-SHOT™ products already used by HEAT to develop latent prints that fluoresce under forensic light sources without RAM application. Testing demonstrated that Lumicyano™ products used in conjunction with CYANO-SHOT™ products were effective at developing latent prints.

Green emitting SrAl2O4:Tb3+ nano-powders for forensic, anti-counterfeiting and optoelectronic devices

Tb3+ ions incorporated strontium aluminate nanopowders were prepared via eco-friendly green ultrasonication followed by combustion method by using Carica papaya milk extract as a fuel/surfactant. The prepared powders were characterized by advanced characterization techniques. X-ray diffraction profiles of the prepared samples confirmed the monoclinic phase of SrAl2O4:Tb3+ (1–11 mol%) and well consistent with PDF number of 74-0794. Rod, mesh and spikes like morphology were confirmed through SEM images. TEM images showed the irregular extended particles with smooth surface and confirm the polycrystalline nature of prepared nanopowders. Upon excitation at 374 nm the photoluminescence emission spectra show intense peaks in the range at 480–620 nm due to the transitions 5D4 → 7FJ (J = 6, 5, 4 and 3) of Tb3+ ions. CIE, CCT and CP results observed were corresponding to intense green colour with (0.21, 0.71), 4621 K and 90% respectively. 7 mol % of Tb3+ doped strontium aluminate was found more suitable for the production of green light component of WLED and for display applications. These compounds were also showed better visualization capabilities to view the LFPs on different porous and nonporous surfaces. Nanopowders were strongly adsorbed by the surfaces which help to visualize the various ridge features including sweat-pores without any background hindrance. UV light of 254 nm wavelength exhibited the clearly visualized symbols with intense green light used for anti-counterfeiting.

Phase and luminescence behaviour of Ce-doped zirconia nanopowders for latent fingerprint visualisation

Present work focuses on the phase evolution, emission behaviour of Ce-doped zirconia nanopowders, calcined under air and argon atmosphere and its application in latent fingerprint visualisation. The different concentration of Ce-doped ZrO2 nanoparticles were prepared via precipitation method using sodium borohydride and calcined at 600 °C under air and argon atmosphere. The tetragonal phase of zirconia was detected for all samples under air atmosphere. However, the crystalline phase of tetragonal zirconia was observed for above 1 mol% Ce-doped ZrO2 samples, calcined under argon atmosphere. A broad photoluminescence emission was observed in the UV and visible range for all samples due to 5D3/2 →7FJ transitions (J = 7/2 and 5/2) of Ce3+ ions. The increase of Ce-concentration causes more distortion in the tetragonal structure of zirconia, and provides an enhanced emission intensity under air atmosphere. However, the emission intensity was found to be similar under argon atmospheric condition due to lower crystallinity of t-zirconia. Further, all the samples lie in the violet-bluish region of the CIE-diagram. The latent fingerprint visualisation was explored using Ce-doped ZrO2 nanopowders on both non-porous and porous surface, and the obtained results validate its use in the forensic applications.

Soil Erosion Assessment and Prediction in Urban Landscapes: A New G2 Model Approach

Soil erosion is a global problem that negatively affects the quality of the environment, the availability of natural resources, as well as the safety of inhabitants. Soil erosion threatens the functioning of urban areas, which was the reason for choosing the territory of the Master Plan of Belgrade (Serbia) as the research area. The calculation of soil erosion loss was analyzed using the G2 erosion model. The model belongs to a group of empirical models and is based on the synthesis of the equation from the Revised Universal Soil Loss Equation (RUSLE) and the Erosion Potential Method (EPM). The estimation of soil degradation was analyzed in two time periods (2001 and 2019), which represent the time boundaries of the management of the Master Plan of Belgrade. The novel approach used in this research is based on using the land cover inventory as a dynamic indicator of the urbanization process. Land cover was identified using remote sensing, machine learning techniques, and the random forest algorithm applied to multispectral satellite images of the Landsat mission in combination with spectral indices. Climatic parameters were analyzed on the basis of data from meteorological stations (first scenario, i.e., 2001), as well as on simulations of changes based on climate scenario RCP8.5 (representative concentration pathways) concerning the current condition of the land cover (second scenario). A comparative analysis of the two time periods identified a slight reduction in total soil loss. For the first period, the average soil loss value is 4.11 t·ha−1·y−1. The analysis of the second period revealed an average value of 3.63 t·ha−1·y−1. However, the increase in non-porous surfaces has led to a change in the focus of soil degradation. Increased average soil loss as one of the catalysts of torrential flood frequencies registered on natural and semi-natural areas were 43.29% and 16.14%, respectively. These results are a significant contribution to the study of soil erosion in urban conditions under the impact of climate change.

The Development of Dusting Method for Dragon Fruit Peel as Fingerprint Visualization

&lt;p&gt;Various fingerprint powder preparations used for fingerprints have a color or contrast and a sticky material for good adhesion. However, some chemical substrates used for fingerprint powders are toxic and have the potential to harm health. This research is essential to overcome this problem using a new natural powder , namely dragon fruit peel powder, as a latent fingerprint development that was simple, non-toxic, and cheaper than commercial used fingerprint powder. Fingerprint development was carried out on non-porous surfaces (aluminium foil, CD, glass preparations) and porous surfaces (HVS paper, spectra paper, paperboard). This study used 90 fingerprint samples based on ethnicity (Batak, Javanese, Malay), blood type, and gender. The development of fingerprints using dragon fruit peel powder resulted in clear visualization on the surface of aluminium foil and glass preparations with sizes of 100 and 200 mesh. Meanwhile, fingerprints on the paper surface resulted in poor visualization because the protrusions of the fingerprints were not visible. The most dominant fingerprint patterns based on ethnicity, blood group, and gender were the loop pattern, then the whorl, and the smallest arch, respectively.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;&lt;em&gt; &lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;

Novel aggregation induced emission based 7-(diethylamino)-3-(4-nitrophenyl)-2H-chromen-2-one for forensic and OLEDs applications

In this report, a novel solvatochromism, aggregation induced emission (AIE) based 7-(diethylamino)-3-(4-nitrophenyl)-2H-chromen-2-one fluorescent probe (CFP) was synthesizes via one-pot multi-component reaction system under ultrasonication method. The synthesized CFP was characterized using different instrumental techniques namely, Fourier transform infrared spectroscopy (FTIR), Proton nuclear magnetic resonance spectroscopy (1H NMR), Mass spectrometer, Scanning electron microscope (SEM), Energy dispersive X-ray analysis (EDAX), Thermal gravimetric analysis (TGA), Transmission electron microscopy (TEM), UV−Vis spectrometry and Fluorescence spectrophotometer. The synthesized CFP produces red emission in solid as well as in liquid state. The synthesized CFP was investigated as a new labeling mediator for the visualization of latent fingerprints (LFPs) on the different non-porous materials surface. The obtained CIE result proves that the organic moiety was extremely helpful for the fabrication of red-light emitting diodes in the display device. The synthesized CFP will play a crucial role in visualizing the LFPs on various materials surface, organic light emitting diodes (OLEDs) and anti-counterfeiting applications.

Improved Hydrogenation Kinetics of TiMn1.52 Alloy Coated with Palladium through Electroless Deposition.

The deterioration of hydrogen charging performances resulting from the surface chemical action of electrophilic gases such as CO2 is one of the prevailing drawbacks of TiMn1.52 materials. In this study, we report the effect of autocatalytic Pd deposition on the morphology, structure, and hydrogenation kinetics of TiMn1.52 alloy. Both the uncoated and Pd-coated materials were characterized using scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD). XRD analyses indicated that TiMn1.52 alloy contains C14-type Laves phase without any second phase, while the SEM images, together with a particle size distribution histogram, showed a smooth non-porous surface with irregular-shaped particles ranging in size from 1 to 8 µm. The XRD pattern of Pd-coated alloy revealed that C14-type Laves phase was still maintained upon Pd deposition. This was further supported by calculated crystallite size of 29 nm for both materials. Furthermore, a Sieverts-type apparatus was used to study the kinetics of the alloys after pre-exposure to air and upon vacuum heating at 300 °C. The Pd-coated AB2 alloy exhibited good coating quality as confirmed by EDS with enhanced hydrogen absorption kinetics, even without activation. This is attributed to improved surface tolerance and a hydrogen spillover mechanism, facilitated by Pd nanoparticles. Vacuum heating at 300 °C resulted in removal of surface barriers and showed improved hydrogen absorption performances for both coated and uncoated alloys.

Blood spatter impact accuracy on nonporous surfaces and how it affects criminal investigation updated

The purpose of this research was to test the validity of the Bathazard equation (sinθ = (W/L) on nonporous, passive, blood-spattered surfaces. The Bathazard equation was formulated and tested solely on porous surfaces. Nonporous and porous surfaces have different properties and react differently affecting the size and shape of the blood spatter. To test the validity of the Bathazard equation, I tested passive drops of blood from average female and male fingertip heights at 90̊, 60̊, and 45̊ angles on porous and nonporous surfaces. Blood drop height and width were measured after immediate impact and again after an hour. An hour was selected because it is the average time from a crime being committed until it is investigated by police in West Virginia. Results show that the angle variation of the porous standards did not typically yield accurate impact angles when using the Bathazard equation. Nonporous surfaces did not yield accurate impact angles for any test using the Bathazard equation. The Bathazard equation is not a suitable formula to use when analyzing passive blood spatter on nonporous surfaces because it yields inaccurate results of blood evidence in criminal cases.

Colorimetric detection of residual quaternary ammonium compounds on dry surfaces and prediction of antimicrobial activity using bromophenol blue.

Controlling and monitoring the residual activity of quaternary ammonium compounds (QACs) are critical for maintaining safe yet effective levels of these agents in the environment. This study investigates the utility of bromophenol blue (BPB) as a safe, rapid and user-friendly indicator to detect in situ residual QACs dried on hard, non-porous surfaces, as well a means to assess their antimicrobial efficacy. At pH 7, BPB has a purple colour which turns blue upon its complexation with QACs such as didecyldimethylammonium chloride (DDAC). BPB itself has no antimicrobial properties up to 400ppm. Within the range of 0-400ppm, BPB colour change was tied to specific DDAC antimicrobial performances with a detection threshold of 100ppm. BPB concentration and application volume could be adjusted such that a colour shift from purple to blue correlated with a set percent reduction (>99·9%) in test bacteria (Staphylococcus aureus and Klebsiella aerogenes). The BPB solutions developed in this study yielded similar colour shifts on polycarbonate and stainless steel surfaces and did not cross-react with chemical ingredients commonly found in sanitizers and disinfectant products. Overall, this study suggests that BPB provides a simple solution to safely monitor the post-application level and biocidal activity of residual dried QACs on surfaces.

Drip stains formed on ice and snow: an observational study

When a crime is committed in colder climates, there is potential for bloodshed to occur in areas covered in ice and/or snow. In this work, we investigate drip stain formation on ice and snow surfaces. We examine the effects of dripping height and surface type on bloodstain size, shape and distribution. Seventy-five drip stains were created from droplets generated perpendicular to the surface across five different dripping heights and three surface types (new snow, powder snow and crust). Digital images of each bloodstain were collected and were analyzed using FIJI. Additionally, high-speed videos were taken of drip stains forming on three types of natural snow surfaces. The bloodstains observed in this study exhibited irregular characteristics compared to those seen in bloodstains on hard, non-porous and non-absorbent surfaces created in ambient laboratory conditions. The type of surface was observed to affect the diameter, circularity and distribution of satellite stains; however, dripping height did not affect these characteristics. While the estimated roughness of the snow surfaces may have influenced the formation of the bloodstains, we suggest that it is not the only surface property involved in bloodstain appearance. Our findings, while preliminary, support future investigation of bloodstain formation on cold complex surfaces.

Contribution to the understanding of the performance differences between commercial current collectors in Li–S batteries

Lithium–sulfur batteries have been recognised as highly promising next-generation batteries, due to their low cost and high theoretical energy density. Despite numerous advances in this technology over the last decade, its commercialisation is still a challenge that has not yet been achieved. Many efforts have been made to improve the problems that these batteries present, mainly by investigating different cathode manufacturing strategies, testing novel Li anodes, new additives in the electrolytes, and modified separators or interlayers. However, the characteristics of the current collectors used in the preparation of the electrodes have been rarely addressed. Three commercial collectors are commonly used in basic research on Li–S batteries: Al foil, carbon coated Al foil (Al-C), and carbon paper (gas diffusion layer, GDL). In this work, a detailed study of the electrochemical response of these commercial collectors has been carried out. The tests were carried out on two S composites formed by carbons of a different natures, commercial carbon black and synthetic N-doped graphene. In addition, the S impregnation method was different, using either melt diffusion at 155 °C or ethylenediamine as S solvent, respectively. In both systems, the results were similar – the electrodes supported on GDL delivered higher specific capacities than those supported on Al and Al-C, with minimal differences between the two. Of the different collector properties examined to explain this behaviour, namely Al corrosion, electrical conductivities, surface-level composition, and surface texture, only the latter had a significant effect in the performance of GDL-based electrodes. SEM images revealed a rough and cracked surface formed by the agglomerated carbon particles that give rise to a complex pore system, predominantly consisting of macropores. All of these features are beneficial for a better anchoring of the active material on the collector surface, in addition to enhancing the wettability of the electrolyte and favouring reaction kinetics. In contrast, the Al-based collector possesses a very smooth and non-porous surface, detrimental to both the active material-substrate interface and the active material impregnation by the electrolyte.

Sensing and sensitive visualization of latent fingerprints on various surfaces using a versatile fluorescent aggregation-induced emission-based coumarin derivative.

The marked rise in criminal activity in society has made a difficult task for forensic scientists who aim to track any crime scene effectively, therefore visualization of latent fingerprints (LFPs) plays an increasingly vital role in forensics. In the present report, a highly sensitive solvatochromism, aggregation-induced emission-based 2-(4-nitrophenyl)-3H-benzocoumarin fluorescent dye (CFD) was fabricated using an ultrasonication protocol. The fluorescence properties of the CFD were analyzed using fluorescence spectrophotometer. The CFD produced a greenish yellow emission in solid and fluid states. An in-depth visualization of LFPs showed detailed ridge patterns under normal and ultraviolet light sources (254 and 365 nm) due to the excellent chemisorption of CFD onto the ridge patterns on the finger. All three types of ridge details were visualized without any background interference when using a simple and quick powder dusting method. Results revealed that, the present fluorescent dye can be used successfully for detection of latent fingerprints (LFPs) on various nonporous substrates surfaces, in organic light-emitting diodes applications (OLEDs), and for electrochemical sensing.

Olanexidine gluconate formulations as environmental disinfectants for enveloped viruses infection control

This study investigated the potential of olanexidine gluconate as environmental disinfectant against enveloped viruses in the suspension test and three non-porous surface tests. In the suspension test, olanexidine gluconate showed immediate virucidal activity. In addition, non-porous surface tests demonstrated that, although the immediate effect of aqueous formulations was weak, the final virucidal efficacy outcompeted that of ethanol for disinfection. Furthermore, the effectiveness of olanexidine gluconate persisted even after drying on environmental surfaces. This study demonstrated the potential usage of olanexidine gluconate formulations as an environmental disinfectant in the infection control of enveloped viruses.