Changes In Spectra Research Articles

Enhancing forensic blood detection using hyperspectral imaging and advanced preprocessing techniques

Bloodstains are pivotal in forensic investigations as they can provide crucial DNA information about individuals involved in a crime. Traditional methods for bloodstain detection, including chemical tests and forensic lights, have limitations such as non-specificity to human blood and susceptibility to false positives. In forensic blood detection, molecular spectroscopy is crucial for identifying the unique spectral fingerprints of blood, which arise from its molecular composition. Hyperspectral imaging (HSI) leverages this principle by capturing a wide spectrum of light for each pixel in an image, allowing for the detailed analysis of various substances. HSI has emerged as a promising alternative, offering non-contact, rapid, and cost-effective detection of bloodstains by analyzing the visible and near-infrared electromagnetic spectrum. This study explores the application of HSI for blood detection, addressing challenges such as spectral mixing, time-related changes in bloodstain spectra, and data complexity. The study introduces a novel framework to optimize HSI data, enhancing the accuracy and efficiency of bloodstain classification, called the Fast Extraction (FE) framework. It includes two stages. The main method in the first one is the Enhancing Transformation Reduction (ETR) method to reduce the dimension and complexity of the HSI. The second stage contains a compatible classification model to enhance feature extraction and classification. Our approach is validated using the HyperBlood datasets and many evaluation methods, demonstrating superior performance compared to state-of-the-art deep learning models. It provides high accuracy (97%–100 %) for all HSIs, overcoming various difficulties and blood collection times.

Both edge substitution effects on thermal conductivity of armchair graphene nanoribbons under tensile strain: From equilibrium molecular dynamics simulations

Thermal conductivity and phonon spectra change of graphene nanoribbon as function of both side edges substitution and strain is investigated using equilibrium molecular dynamics. Under small strain, the edge’s partial substitution by graphane plays effect role to change the phonon mode of GNR. Under large tensile strain, reduction ratio of thermal conductivity is the largest in case of fluorographane hybrid and the smallest in case of graphane hybrid. Especially, under 16 % strain, the thermal conductivity of GNR is reduced until 13 % by edges substitution of graphane. The phonon spectra shift peaks towards low frequency at high frequency range (>50 THz).

Deciphering Spectroscopic Signatures of Competing Ca2+ - Peptide Interactions.

Calcium-protein interactions are of paramount importance in biochemistry. They are a key element in a number of biological processes, such as neuronal signaling. Therefore, an understanding of the interaction at the molecular level is highly desirable. Here, we study the zwitterionic model peptide l-alanyl-l-alanine (2Ala), which has two distinct and competing binding sites for Ca2+: The carbonyl of the peptide bond and the C-terminus, the carboxylate group. We perform linear and two-dimensional IR spectroscopy experiments and find that the spectroscopic signatures of both moieties in the IR spectra change in amplitude and peak position upon the addition of CaCl2: A blueshift of the asymmetric carboxylate band and a redshift for the amide I mode. Ab initio molecular dynamics simulations confirm the direct interaction of the Ca2+ ion at both the carboxylate and the amide CO site leading to different spectral responses. The blueshift of the asymmetric carboxylate band is caused by a localization of the charge, leading to a decoupling of the CO stretching modes of the carboxylate group. The slight redshift of the amide I mode of 2Ala upon the addition of CaCl2 contrasts the blueshift that has been observed for isolated amide motifs, such as N-methylacetamide (NMA). This difference is caused by the smaller number of water molecules being replaced by the Ca2+ ion for 2Ala's amide compared to less sterically hindered, isolated amide carbonyls, in conjunction with vibrational Stark effects. Our results highlight the importance of considering potential competing binding sites, such as the amide CO backbone, the termini and residues, as well as the nature of the hydration of both peptide and ion, when exploring ions' interacting with small peptides and larger proteins.

Investigation of Changes in the Reflection Spectrum of Human Blood When Exposed to Laser Radiation With Wavelengths of 450 or 980 nm.

This study aimed to determine and explain changes in the reflectance spectrum of human blood in vitro when exposed to laser radiation at wavelengths of 450 or 980 nm. Reflectance spectra of venous blood samples were measured before and after exposure to a single pulse of 450 or 980 nm laser radiation. A numerical optical model based on the Monte Carlo method was applied. Laser irradiation at 450 and 980 nm caused the most significant changes in the reflectance spectrum around 600 nm, associated with alterations in blood oxygen saturation. The maximum efficiency of reducing oxygen saturation was 0.20%/W for 980 nm and 0.72%/W for 450 nm, likely due to differences in blood absorption at these wavelengths. The greatest change in intensity reflectance spectra and oxygen saturation of human venous blood occurs when exposed to laser radiation at 450 nm, not at 980 nm.

Multiphysical description of atmospheric pressure interface chemical ionisation in MION2 and Eisele type inlets

Abstract. Chemical ionisation inlets are fundamental instrument components in chemical ionisation mass spectrometry (CIMS). However, the sample gas and reagent ion trajectories are often understood only in a general and qualitative manner. Here, we evaluate two atmospheric pressure interface chemical ionisation inlets (MION2 and Eisele type inlet) with 3D computational fluid dynamics physicochemical models regarding the reagent ion and sample gas trajectories and estimate their efficiencies of reagent ion production, reagent ion delivery from the ion source volume into the ion–molecule mixing region, and the interaction between reagent ions and target molecules. The models are validated by laboratory measurements and quantitatively reproduce observed sensitivities to tuning parameters, including ion currents and changes in mass spectra. The study elucidates how the different transport and chemical reactions proceed within the studied inlets, where space charge can already be relevant at ion concentrations as low as 107 cm−3, and compares the two investigated inlet models. The models provide insights into how to operate the inlets and will help in the development of future inlets that further enhance the capability of CIMS.

Imaging the innermost circumstellar environment of the red supergiant WOH G64 in the Large Magellanic Cloud

Significant mass loss in the red supergiant (RSG) phase has great influence on the evolution of massive stars and their final fate as supernovae. We present near-infrared interferometric imaging of the circumstellar environment of the dust-enshrouded RSG WOH G64 in the Large Magellanic Cloud. WOH G64 was observed with the GRAVITY instrument at ESO's Very Large Telescope Interferometer (VLTI) at 2.0--2.45 mu m . We succeeded in imaging the innermost circumstellar environment of WOH G64 -- the first interferometric imaging of an RSG outside the Milky Way. The reconstructed image reveals elongated compact emission with a semimajor and semiminor axis of sim 2 and sim 1.5 mas (sim 13 and 9 $R_ star ), respectively. The GRAVITY data show that the stellar flux contribution at 2.2 mu m \ at the time of our observations in 2020 is much lower than predicted by the optically and geometrically thick dust torus model based on the VLTI/MIDI data taken in 2005 and 2007. We found a significant change in the near-infrared spectrum of WOH G64: while the (spectro)photometric data taken at 1--2.5 mu m \ before 2003 show the spectrum of the central RSG with H$_2$O absorption, the spectra and prime photometric data taken after 2016 are characterized by a monotonically rising continuum with very weak signatures of H$_2$O . This spectral change likely took place between December 2009 and 2016. On the other hand, the mid-infrared spectrum obtained in 2022 with VLT/VISIR agrees well with the spectra obtained before 2007. The compact emission imaged with GRAVITY and the near-infrared spectral change suggest the formation of hot new dust close to the star, which gives rise to the monotonically rising near-infrared continuum and the high obscuration of the central star. The elongation of the emission may be due to the presence of a bipolar outflow or effects of an unseen companion.

Characteristics of surface modified sugarcane bagasse cellulose: application of esterification and oxidation reactions

Research on polymer matrix composites has become increasingly important in both the academic and industrial sectors. The study of polymer-natural fiber composites, known for their eco-friendly properties, has gained significance. Sugarcane bagasse fibers, abundant as discarded agricultural byproducts, offer improved properties such as density, rigidity, strength, and cost-effectiveness, enhancing sustainability. As a result, experiments were performed on cellulose fibers pre-treated from sugarcane bagasse using 5% NaOH solution by simply soaking them for 4–5 h followed by washing with water. Further modifications involved esterification using phthalic anhydride and phthaloyl chloride via steam baths at 90 °C and oxidation using sodium percarbonate with a phase transfer catalyst (Adogen) at 80 °C. These chemically altered cellulose fibers exhibited significant peak changes in the FTIR spectra, a reduced crystallinity index in the XRD pattern, increased thermal stability as evidenced by TGA curve, and improved surface roughness in the SEM analysis. This paper emphasizes successful pretreatment procedures for isolating cellulose fibers from sugarcane bagasse and introduces three chemical treatments for surface functionalization which might find applications in the preparation of biocomposites.

Changes in spectra of cultivated and gathered plants in the Bronze Age

The Bronze Age (BA) in Central Europe witnessed significant transformations in various aspects of human activities. This study focuses on changes in subsistence strategies during the BA, represented by the assortment of edible plants. We examined charred macroremains from 39 archaeological sites in the Czech Republic. Our aims include providing an overview of crop records, determining the dating of new crop introductions, and identifying spatial patterns of the assortment changes. The results indicate a complex agricultural transformation. Emmer and einkorn dominated in the Early Bronze Age (EBA), while the broomcorn millet was widespread in the Middle Bronze Age (MBA). The Late Bronze Age (LBA) saw increased cereal and pulse diversity, whereas the Final Bronze Age (FBA), characterised by coexisting cereals, represented a terminal stage of the process of gradually evolving subsistence strategies. The study highlights the sudden introduction of broomcorn millet in the MBA and expanding the range of crops, which allowed more flexible responses to local conditions and a better distribution of field work throughout the year.

Manganese diluted TlInS2 layered semiconductor: Optical, electronic and magnetic properties

Manganese–doped TlInS2 (TlInS2+Mn) layered semiconductors with different doping concentrations of about 0.1 and 0.3 at. percent were investigated. Photo–induced current transient spectroscopy (PICTS) measurements in the temperature range of 80 and 300 K have been made for identifying energy levels related to Mn dopant within the electronic bandgap of TlInS2+Mn crystal. Optical absorption spectra in the photon energy range of ∼1.8–3.1 eV have been extracted by fitting the transmittance spectra of TlInS2+Mn recorded at the temperatures varied from ∼40–300 K. A redshift trend of the absorption edge with increasing of temperature was observed. On the other hand, a blue shift in the absorption edge with Mn doping was observed in the absorption spectra. The Mn dopant induced photoluminescence (PL) was also investigated in the visible region ranging from 320 to 960 nm. Seven peaks were observed in the PL spectra of Mn doped TlInS2 crystal in the regions both ∼960–620 nm (∼1.3–2 eV) and ∼620–320 nm (∼2–3.8 eV) due to the electronic states of Mn ions. Laser–induced breakdown spectroscopy (LIBS) technique was applied to establish of the elemental chemical composition and to confirm presence of each constituent element in TlInS2:Mn. The dc magnetization measurements of TlInS2+Mn performed in a wide temperature range of ∼5 and ∼300 K revealed different (diamagnetic and paramagnetic states) magnetic phases inside the studied temperature range. The X–band electron paramagnetic resonance (ESR) experiments were carried out in the low–temperature phase of TlInS2+Mn to probe the structure of Mn centers in TlInS2. The measurements revealed that the ESR spectrum changes drastically in the low–temperature phase of TlInS2+Mn bulk sample. Finally, a detailed density functional theory (DFT) based computational investigation of electronic band structures, density of states and optical properties of TlInS2+Mn compound has been performed. The results of ab–initio calculations are discussed for three possible states when the manganese atom was doped by replacing either the Tl, In or S atoms in the unit cell of TlInS2. Additionally, the effect of interstitial Mn dopant on the electronic structure and optical properties of TlInS2 material has been simulated.

Mechanical and Thermal Degradation-Related Performance of Recycled LDPE from Post-Consumer Waste.

This paper presents research aimed at laboratory experiments on static and cyclic fatigue testing of low-density polyethylene (LDPE) recovered from post-consumer waste in order to develop a recycled product exhibiting satisfactory mechanical and thermo-mechanical properties. The results of the cyclic fatigue tests set up to 80% of the maximum load in static tensile testing demonstrated satisfactory functionality of the recycled material developed by using the injection molding process. There was no significant change in the tensile strength under static and cyclic fatigue tests. Under cyclic loading, there was a quasi-static effect manifested by plastic deformation, and the displacement increased significantly. The static and cyclic tensile tests indicated improvement in the mechanical performance of the recycled LDPE as compared to the virgin material, owing to the high quality of the regranulates. Fourier Transform Infrared Spectroscopy (FTIR) was conducted to analyze the functional groups in virgin and recycled LDPE samples. The analysis showed no significant change in the transmittance spectra. The thermal degradation performance was also analyzed by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). The results were quite similar for both virgin and recycled LDPE.

Analysis of the changes of bacterial spectrum and drug resistance in sputum culture of ICU children in a hospital of pediatric in Jiangsu Province from 2017 to 2022

Objective: To investigate the changes of the distribution and drug resistance profile of bacteria from ICU children with lower respiratory tract infection (LRTI) in Suzhou City, Jiangsu Province from 2017 to 2022. Methods: From January 2017 to December 2022, a cross-sectional observational study on the bacterial spectrum analysis among intensive care unit (ICU) children with LRTI was conducted in Children's Hospital of Soochow University. The bacteria was cultivated by culture methods from sputum samples, and identified by MALDI-TOF mass spectrometry. Drug sensitivity tests were performed by the VITEK2 Compact fully automated analysis system and the paper slide method. The χ2 test or Fisher's exact probability was used to analyze the changes of the distribution of sputum culture-positive bacteria and drug resistance in ICU children. Results: The overall detection rate of sputum culture was 42.06% (1 182/2 810). Staphylococcus aureus (25.63%,303/1 182), Acinetobacter baumannii (13.62%,161/1 182) and Haemaphilus influenzae (13.28%,157/1 182) were the top three. Proportions of Acinetobacter baumannii (17.90% vs. 11.02%,χ²=11.17, P=0.001), especially carbapenem-resistant Acinetobacter baumannii (43.70% vs. 23.50%, χ²=15.21, P<0.001) increased significantly from 2020 to 2022. However, the proportions of Haemophilus influenzae (8.50% vs. 16.19%, χ²=14.27, P<0.001), Streptococcus pneumoniae (8.50% vs. 15.92%, χ²=13.42, P<0.001) and extended-spectrum-lactamase producing Escherichia coli (8.89% vs. 18.00%, χ²=5.45, P=0.025) decreased. Drug resistant results showed that Acinetobacter baumannii was obviously more resistant to imipenem (χ²=4.43, P=0.035) and levofloxacin (χ²=12.53, P<0.001), while more sensitive to minocycline (χ²=8.34, P=0.004). Escherichia coli showed a significant increase in resistance to piperacillin tazobactam (χ²=8.29, P=0.008) and cefoperazone sulbactam (χ²=5.07, P=0.024) from 2020 to 2022; Klebsiella pneumoniae consistently maintained a resistance rate of more than 60% to first and second-generation cephalosporins, and remain susceptible to quinolones and carbapenems. Staphylococcus aureus remained highly susceptible to levofloxacin (drug resistance rate: 2.31%,7/303) and sulfamethoxazole/trimethoprim (drug resistance rate: 4.95%,15/303) from 2020 to 2022. Conclusion: Higher detection and resistance rates of Acinetobacter baumannii from sputum culture in ICU children from 2020 to 2022 were explored. Resistance of Escherichia coli to β-lactamase inhibitor combinations was more serious. Regular monitoring the changes of the etiology of respiratory tract infections in ICU Children is particularly important for the prevention and treatment of multidrug-resistant bacterial infections.

Best descriptors for predicting noise annoyance and spectrum-based penalty of steady-state wideband noise

Many objective descriptors (i.e., single-number quantities) are available in the literature for the objective assessment of noise annoyance of wideband, steady-state sounds. However, there is no definitive understanding of which descriptors best correspond to subjective annoyance. Our purpose is to assess how different descriptors correspond with differences in noise annoyance resulting from changes in A-weighted sound level and spectrum. This investigation is based on recently published results from a psychoacoustic experiment conducted by Kuusinen et al. [1]. They investigated 23 steady-state wideband noises with various spectral shapes within 32-48 dB LAeq, and participants rated them in terms of subjective annoyance. The study revealed that penalty due to spectrum shape could be even 10 dB. Here, we present a follow up analysis focusing on objective noise descriptors. The results indicate that many descriptors are strongly associated with noise annoyance ratings, while Spectral Centroid and Sharpness appear to be the best candidates to predict spectrum-based penalty.

Annoyance caused by simultaneous exposure to noise and seat vibrations inside of a mini excavator: multimodal interaction and the effects of changes in low-frequency content of the sound signal

Drivers of commercial vehicles are exposed to noise and vibrations during their occupation. The signal characteristics of these exposures can lead to different degrees of annoyance perception, even below the legal daily exposure limits. In addition, simultaneous exposure to sound and vibration may lead to potential interaction effects between the two stimuli, influencing the total annoyance perception. Therefore, a perception experiment was designed to ask the participants about the perceived total annoyance caused by simultaneous noise and seat vibrations in commercial vehicles, presenting modified sound and seat vibrations, recorded inside of a mini-excavator. Multimodal interaction effects of noise and vibrations were investigated by changing the intensity of both stimuli. Furthermore, the influence of low-frequency signal components of the sound signal with and without simultaneous seat vibrations was investigated by specific changes in the sound spectrum.

Charge order near the antiferromagnetic quantum critical point in the trilayer high Tc cuprate HgBa2Ca2Cu3O8+δ

We study the transport properties of underdoped trilayer cuprate HgBa2Ca2Cu3O8+δ with doping level p = 0.10–0.12 in magnetic field up to 88 T. We report for the first time in a cuprate superconductor a dramatic change of the quantum oscillation spectrum versus temperature, which is accompanied by a sign change of the Hall effect below T ≈10 K. Based on numerical simulations, we infer a Fermi surface reconstruction in the inner plane from an antiferromagnetic state (hole pockets) to a biaxial charge density wave state (electron pockets). We show that both orders compete and share the same hotspots of the Fermi surface, and we discuss our result in the context of spin-fermion models.

The Interaction of Myeloperoxidase with the Industrial Contaminant 6-PPD: A Potential Pathway for Reactive Metabolites.

6-PPD (N-[1,3-dimethylbutyl]-N'-phenyl-p-phenylenediamine) is an industrial antioxidant reported to be an environmental contaminant. It was found to be highly toxic to coho salmon and potentially other aquatic organisms. The toxicity of 6-PPD in humans, however, remains unknown. The neutrophil enzyme myeloperoxidase (MPO) is known to catalyze xenobiotic metabolism; therefore, its role in 6-PPD cytotoxicity was investigated using the MPO-rich HL-60 cell line. UV-visible spectroscopy and liquid chromatography-mass spectrometry (LC/MS) were performed to investigate the MPO-mediated oxidation of 6-PPD and identify possible metabolites in the absence and presence of glutathione (GSH). 6-PPD's cytotoxicity, effect on mitochondrial membrane potential (MMP), and GSH-depleting ability in HL-60 cells were assessed. Electron paramagnetic resonance (EPR) was used to determine GSH radical formation using DMPO, and mitochondrial-derived superoxide was assessed with the mito-TEMPO-H probe. Evaluation of the 6-PPD-induced cellular injury pathways was performed by preincubating an antioxidant and an MPO inhibitor with HL-60 cells. UV-vis analysis of MPO-catalyzed oxidation of 6-PPD demonstrated changes in the 6-PPD spectrum, whereas the addition of GSH altered the spectrum, indicating possible GSH conjugate formation. LC/MS showed the formation of multiple products, including GSH-6-PPD conjugates and a GSH conjugate to a 4-hydroxydiphenylamine (a known 6-PPD degradant), which could potentially induce cytotoxicity. 6-PPD demonstrated concentration-dependent cytotoxicity, and cellular GSH levels were decreased by 6-PPD. Similarly, the level of MMP decreased, suggesting mitochondrial depolarization. Furthermore, the EPR spin probe for mitochondrial superoxide showed a positive relationship with 6-PPD concentration, and EPR spin-trapping demonstrated 6-PPD concentration-dependent GSH radical signal intensity using MPO/H2O2. The GSH precursor, NAC, demonstrated partial cytoprotection against 6-PPD; however, the MPO inhibitor PF-1355 surprisingly showed no significant cytoprotective effect. Our results suggest that MPO could be a potential catalyst for 6-PPD toxicity in humans. However, MPO inhibition did not significantly affect cellular viability, suggesting an MPO-independent toxicity pathway. These findings warrant a deeper investigation to determine 6-PPD mammalian toxicity pathways.

Simultaneous In Vivo Imaging of Neutrophil Elastase and Oxidative Stress in Atherosclerotic Plaques Using a Unimolecular Photoacoustic Probe.

Atherosclerosis, a major global health concern with high morbidity and mortality rates, involves complex interactions of chronic inflammation, oxidative stress, and proteolytic enzymes. Conventional imaging methods struggle to capture the dynamic biochemical processes in atherosclerotic plaques. Here, we introduce a novel unimolecular photoacoustic probe (UMAPP) designed with specific binding sites for neutrophil elastase (NE) and the redox pair O2⋅-/GSH, enabling real-time monitoring of oxidative stress and activated neutrophils in plaques. UMAPP, comprising a boron-dipyrromethene (BODIPY) core linked to a hydrophilic NE-cleavable tetrapeptide and dual oxidative stress-responsive catechol moieties, facilitates NE-mediated modulation of photoinduced electron transfer impacting photoacoustic intensity at 685 nm (PA685). Furthermore, oxidation and reduction of catechol groups by O2⋅- and GSH induce reversible, ratiometric changes in the photoacoustic spectrum (PA745/PA685 ratio). Initial UMAPP applications successfully distinguished atherosclerotic and healthy mice, evaluated pneumonia's effect on plaque composition and verified the probe's effectiveness in drug-treatment studies by detecting molecular alterations before visible histopathological changes. The integrated molecular imaging capabilities of UMAPP offer promising advancements in atherosclerosis diagnosis and management, enabling early and accurate identification of vulnerable plaques.

Simultaneous In Vivo Imaging of Neutrophil Elastase and Oxidative Stress in Atherosclerotic Plaques Using a Unimolecular Photoacoustic Probe

AbstractAtherosclerosis, a major global health concern with high morbidity and mortality rates, involves complex interactions of chronic inflammation, oxidative stress, and proteolytic enzymes. Conventional imaging methods struggle to capture the dynamic biochemical processes in atherosclerotic plaques. Here, we introduce a novel unimolecular photoacoustic probe (UMAPP) designed with specific binding sites for neutrophil elastase (NE) and the redox pair O2⋅−/GSH, enabling real‐time monitoring of oxidative stress and activated neutrophils in plaques. UMAPP, comprising a boron‐dipyrromethene (BODIPY) core linked to a hydrophilic NE‐cleavable tetrapeptide and dual oxidative stress‐responsive catechol moieties, facilitates NE‐mediated modulation of photoinduced electron transfer impacting photoacoustic intensity at 685 nm (PA685). Furthermore, oxidation and reduction of catechol groups by O2⋅− and GSH induce reversible, ratiometric changes in the photoacoustic spectrum (PA745/PA685 ratio). Initial UMAPP applications successfully distinguished atherosclerotic and healthy mice, evaluated pneumonia‘s effect on plaque composition and verified the probe‘s effectiveness in drug‐treatment studies by detecting molecular alterations before visible histopathological changes. The integrated molecular imaging capabilities of UMAPP offer promising advancements in atherosclerosis diagnosis and management, enabling early and accurate identification of vulnerable plaques.

Comparative study between UVB 313 nm, UVC 254 nm, and far UVC 222 nm light on the aging of polyamide 66

Polyamide-66 underwent substantial growth worldwide in the late 1930′s. It can be found in several public spaces. After 2019, due to the coronavirus disease (COVID-19), the sanitization of the interior of aircraft and public spaces by using UV light became important. Most of all, the effect of the far UVC 222 nm became a research hot spot and is still a research blank. In the present work, a comparative study on the post-exposure damage of polyamide- 66 occurred when controlled ultraviolet irradiation (UVC 254 nm, far UVC 222 nm, UVB 310 nm) and moisture-condensation were carried out. Chemical (FTIR), thermal (DMA), and nano-mechanical properties were evaluated. FTIR analysis showed the formation of O-H and/or N-H bonds since there appeared absorptions at 3400 cm−1 along with the vanishing of other signals related to C-N bonding. These changes are more evident in samples exposed to UVC 254 nm followed by samples that were irradiated with UVC 222 nm. Samples that were aged with UVA 313 nm didn't show a change in FTIR spectra. FTIR on spectra and nanoindentation showed that UVB 313 nm produced a lower aging effect on this material. In contrast, UVC 254 nm light caused the highest degree of surface chemical-mechanical change attributed to cleavage/crosslinking reactions initiated by free radicals produced by UV light and moisture. On the contrary, far UVC 222 nm light presented moderate effects on Polyamide-66. Glass-transition temperature (Tg) diminished as the time to exposure increased attributed to water absorption and surface damage, being the highest change at −16.05 °C for samples irradiated with 245 UVC nm. However, the potential of far UVC 222 nm light for COVID-19 sanitization, with no significant degradation effects on polymeric materials, is a promising finding that should be further explored and could provide a hopeful solution in the fight against the pandemic.

Multi-physical quantities sensing based on the nematic liquid crystal Janus metastructure in theory

Breaking through the idea limitation of traditional single-scale and single-function sensors, a multi-scale and multi-function Janus metastructure (JMS) is proposed in this article, which is constructed by the specific methods to break its parity. Using the change of transmission spectrum, JMS can realize multi-physical quantities detection with different sensing performances, when electromagnetic waves propagate on positive and negative scales respectively. For selective gas detection, JMS can conveniently detect 0–3.5 % methane concentrations with sensitivity (S) of 22.932 THz/RIU and 0–3 % hydrogen concentrations with S of 43.494 THz/RIU, avoiding the problem of complex and dangerous external operation conditions required for previous gas sensors. Based on the electro-optical effect of nematic liquid crystal, JMS can realize wide-range electric field direction (EFD) sensing of 10°–80° and 100°–170° by taking the advantages of multi-scale detection, which is wider than existing 0°–90° EFD sensors. Because nematic liquid crystal is thermotropic, JMS can also achieve accurate temperature detection of 283.15–318.15 K. Finally, through comparison, it is proved that JMS proposed has the potential of multi-scenario applications, and meets the urgent demand for excellent performance sensors in the fields of dangerous gas transportation, atmospheric EFD detection and industrial manufacturing temperature control.

Chromophore Structural Change during the Photocycle of a Light-Driven Cl- Pump from Mastigocladopsis repens: A Cryogenic Raman Study.

Microbial rhodopsins are the most widely distributed photoreceptors that bind a retinal Schiff base chromophore. Among them, a light-driven Cl- pump discovered from Mastigocladopsis repens (MrHR) is distinctive in that it has the structural features of both H+ and Cl- pumps. While the photocycle has been characterized by light-induced changes of the absorption spectrum, the structural changes of the retinal chromophore remain largely unknown. In this study, we examined the chromophore structural changes of MrHR by using cryogenic Raman spectroscopy. We observed five photointermediates─K, L, N1, N2, and MrHR'─that show distinct vibrational spectra, indicating atypical chromophore structures, e.g., small distortion in the K intermediate and Schiff base configurational change in the MrHR' intermediate. Based on the Raman spectra of two N intermediates (N1 and N2), we propose that N1 is the Cl--bound state and N2 is the Cl--unbound state, which are responsible for the Cl- release and uptake, respectively, to achieve Cl- pumping.