Maximum Absorption Research Articles

Optical response in a high-TcYBCO nanowire

We demonstrate the optical response from high-Tc superconductor nanowires at temperatures above that of liquid nitrogen. Using hard oxide Al2O3 as a mask material, we achieved miniaturized YBa2Cu3O7−δ wires with widths nearing 100 nm, a significant milestone for highly sensitive photodetectors. We investigated the photoresponse of these nanowires at temperatures almost an order of magnitude higher than previously reported, under varying temperature and bias current conditions. Our findings reveal a strong correlation between the optical response and the critical parameters of the superconductor, with peak optical responses close to the critical values of temperature and bias current density. Nanowire response to wavelengths from visible to near-infrared range demonstrated a pronounced absorption maximum at temperatures below Tc. These results lay a solid foundation for the development of high-Tc superconductor nanowire single-photon detectors, understanding of nanoscale high-Tc superconductor structure optical behavior, and advancing the prospects of quantum technologies.

Phytotoxicity, cytogenotoxicity and antimicrobial potential of extracts with gold-silver bimetallic nanoparticles obtained from pteridophyte spores

Investigating the toxicity of naturally occurring or synthesized nanoparticles for various applications is absolutely necessary for environmental protection and safety use. The aim of these research was to investigated the phytotoxicity, cytogenotoxicity and antibacterial potential of the extracts with gold-silver bimetallic nanoparticles (Au-Ag NPs) obtained from green synthesis in Asplenium scolopendrium L. and Dryopteris filix-mas (L.) Schott spores extracts. To our knowledge, this is the first report of the Au-Ag NPs phytosynthesis based on extracts obtained from fern spores. UV-Vis spectroscopy analysis of the samples revealed the maximum absorbance, characteristic of samples with bimetallic nanoparticles, which varied depending on the Au:Ag ratio. Energy-dispersive X-ray spectroscopy confirmed the presence and distribution of Au, Ag and other chemical elements. The presence of specific secondary metabolites in the extracts that helped in NPs biosynthesis stimulated growth processes. Good results were recorded for some Dryopteris filix-mas samples, correlated with a significantly increased mitotic index. Cell viability decreased significantly in three of the nanoformulations. Only extracts with Au-Ag NPs showed antimicrobial effect against Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633 and Escherichia coli ATCC 8739. The testing of the antibacterial potential of these extracts must be extended to other bacterial strains and other microorganisms, the search of new antimicrobial resources being an urgent necessity nowadays.

Phytotoxicity, cytogenotoxicity and antimicrobial potential of extracts with gold-silver bimetallic nanoparticles obtained from pteridophyte spores

Investigating the toxicity of naturally occurring or synthesized nanoparticles for various applications is absolutely necessary for environmental protection and safety use. The aim of these research was to investigated the phytotoxicity, cytogenotoxicity and antibacterial potential of the extracts with gold-silver bimetallic nanoparticles (Au-Ag NPs) obtained from green synthesis in Asplenium scolopendrium L. and Dryopteris filix-mas (L.) Schott spores extracts. To our knowledge, this is the first report of the Au-Ag NPs phytosynthesis based on extracts obtained from fern spores. UV-Vis spectroscopy analysis of the samples revealed the maximum absorbance, characteristic of samples with bimetallic nanoparticles, which varied depending on the Au:Ag ratio. Energy-dispersive X-ray spectroscopy confirmed the presence and distribution of Au, Ag and other chemical elements. The presence of specific secondary metabolites in the extracts that helped in NPs biosynthesis stimulated growth processes. Good results were recorded for some Dryopteris filix-mas samples, correlated with a significantly increased mitotic index. Cell viability decreased significantly in three of the nanoformulations. Only extracts with Au-Ag NPs showed antimicrobial effect against Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633 and Escherichia coli ATCC 8739. The testing of the antibacterial potential of these extracts must be extended to other bacterial strains and other microorganisms, the search of new antimicrobial resources being an urgent necessity nowadays.

Quantification of Lobeglitazone Sulfate in Bulk and Tablet Dosage Form by a Validated UV Spectroscopy Method: A New Thiazolidinedione Anti-diabetic Drug

Background: Lobeglitazone sulfate is a novel thiazolidinedione drug used for the therapy of type 2 diabetes. Recent pre-clinical studies show that the drug is also effective in attenuating mucus hypersecretion and airway inflammation caused due to ovalbumin-induced asthma. Objective: This study aimed to develop an accurate, simple, and cost-effective analytical method for the quantification of lobeglitazone sulfate in bulk and pharmaceutical dosage forms by UV spectrophotometric technique. Methods: The drug was identified by FTIR (ATR) instrument and the method development was performed with methanol as the solvent. In compliance with the ICH Q2(R2) guidelines, all the important validation parameters, such as linearity, accuracy, Limit of Detection (LOD), precision, specificity, Limit of Quantification (LOQ), and robustness were deter-mined. Results: The maximum absorption wavelength of lobeglitazone sulfate was found to be 248 nm. The linearity range was established from 2-14 μg/mL with a linearity equation of y = 0.0361x + 0.0024 and r² = 0.9987. The accuracy of the analytical method was found to be in the range of 99.37-100.41%. The precision studies were performed under three subsets of re-peatability, intra-day, and inter-day, and the results recorded were within the acceptance lim-its, i.e., %RSD (<2%). The developed analytical method's Limit of Detection (LOD) and Limit of Quantification (LOQ) values were 0.07 μg/mL and 0.22 μg/mL, respectively. Conclusion: The developed analytical method has been found to be valuable in regular qual-ity control analysis of lobeglitazone sulfate in pharmaceutical industries. The adopted ap-proach of the developed method has been found to be facile, accurate, precise, and economi-cal.

Functional and structural characterization of a thermostable flavin reductase from Geobacillus mahadii Geo-05

Flavin reductases play a vital role in catalyzing the reduction of flavin through NADH or NADPH oxidation. The gene encoding flavin reductase from the thermophilic bacterium Geobacillus mahadii Geo-05 (GMHpaC) was cloned, overexpressed in Escherichia coli BL21 (DE3) pLysS, and purified to homogeneity. The purified recombinant GMHpaC (Class II) contains chromogenic cofactors, evidenced by maximal absorbance peaks at 370 nm and 460 nm. GMHpaC stands out as the most thermostable and pH-tolerant flavin reductase reported to date, retaining up to 95 % catalytic activity after incubation at 70 °C for 30 min and maintaining over 80 % activity within a pH range of 2–12 for 30 min. Furthermore, GMHpaC's catalytic activity increases by 52 % with FMN as a co-factor compared to FAD and riboflavin. GMHpaC, coupled with 4-hydroxyphenylacetate-3-monooxygenase (GMHpaB) from G. mahadii Geo-05, enhances the hydroxylation of 4-hydroxyphenylacetate (HPA) by 85 %. The modeled structure of GMHpaC reveals relatively conserved flavin and NADH binding sites. Modeling and docking studies shed light on structural features and amino acid substitutions that determine GMHpaC's co-factor specificity. The remarkable thermostability, high catalytic activity, and general stability exhibited by GMHpaC position it as a promising enzyme candidate for various industrial applications.

Tuning the photovoltaic potential of thiazole based materials via incorporation of selenophene and electron acceptors rings at peripheral positions: A DFT approach

The non-fullerene acceptor (NFA) chromophores have sparked scientific and economic interest, due to their rapid advancements in power conversion efficiencies. Therefore, a series of new chlorothiazole based compounds (STM1-STM6) with A1–π–A2–π–A1 configuration was designed using reference chromophore (STMR). Structural modifications were made via incorporating selenophene and extended acceptor units, to enhance photovoltaic response in the designed materials. Density functional theory/time dependent-density functional theory (DFT/TD-DFT) calculations were executed at M06/6-311G (d,p) level to investigate key electronic and photovoltaic properties of STM1-STM6. So, various analyses such as UV–Visible, frontier molecular orbitals (FMOs), transition density matrix (TDM), density of states (DOS), open circuit voltage (Voc) and binding energy (Eb) were conducted to comprehend the photovoltaic properties. The designing in structural aspects with terminal acceptors and π-linker induced a reduction in energy gaps (ΔE = 2.078–2.237 eV) with an enhancement in the bathochromic shift (λmax = 744.650–798.250 nm in chloroform) than reference compound. A higher exciton dissociation rate was observed in all the compounds due to lower binding energy values (Eb = 0.525–0.572 eV). Additionally, TDM and DOS findings further endorsed the effective charge delocalization from HOMO to LUMO. Among all the examined compounds, STM3 exhibited the smallest band gap (2.078 eV), highest absorption maxima (798.250 nm), and the lowest exciton binding energy (0.525 eV), indicating significant electronic properties. Moreover, Voc analysis was conducted with respect to HOMOPBDBT-LUMOacceptor for all the designed chromophores; consequently, STM2 demonstrated a substantial Voc value of 1.647 V. Similarly, electron hole analysis was also conducted and significant electron and hole density was observed in all the investigated compounds, especially in STM2. The entitled compounds with photovoltaic potential would be considered as promising materials for the development of solar energy devices.

Integrated design of multifunctional lightweight magnetic cellulose-based aerogel with 1D/2D/3D hierarchical network for efficient microwave absorption

Developing electromagnetic wave absorption materials that are both multifunctional and high-performance, while using rational dimensional design and component strategies, remains extremely challenging. Herein, multidimensional, gradient porous, electrically, and magnetically conductive carbon nanocellulose aerogels composed of nanocellulose and highly oriented Ni chains are prepared through freeze-drying and subsequent low-temperature annealing. Interestingly, the Ni/CNCA composite achieves exceptional microwave absorption with a minimum reflection loss (RLmin) value of −62.0 dB and a maximum effective absorption bandwidth (EAB) of 6 GHz, covering the entire Ku-band. The superior electromagnetic wave absorption stems from 1D/2D/3D double-supported interpenetrating network with satisfactory impedance matching, dielectric/magnetic losses, interface/dipole polarization, and multiple/reflection scattering. Furthermore, the Ni/CNCA exhibits a low density, excellent mechanical adaptability, hydrophobicity, and corrosion resistance. This work introduces innovative approaches for developing lightweight, multifunctional microwave absorbers for practical applications.

Computer-aided drug design supporting sunscreen research: a showcase study using previously synthesized hybrid UV filter-antioxidant compounds.

Although quantum mechanical calculations have proven effective in accurately predicting UV absorption and assessing the antioxidant potential of compounds, the utilization of computer-aided drug design (CADD) to support sustainable synthesis research of new sunscreen active ingredients remains an area with limited exploration. Furthermore, there are ongoing concerns about the safety and effectiveness of existing sunscreens. Therefore, it remains crucial to investigate photoprotection mechanisms and develop enhanced strategies for mitigating the harmful effects of UVR exposure, improving both the safety and efficacy of sunscreen products. A previous study conducted synthesis research on eight novel hybrid compounds (I-VIII) for use in sunscreen products by molecular hybridization of trans-resveratrol (RESV), avobenzone (AVO), and octinoxate (OMC). Herein, time-dependent density functional theory (TD-DFT) calculations performed in the gas phase on the isolated hybrid compounds (I-VIII) proved to reproduce the experimental UV absorption. Resveratrol-avobenzone structure-based hybrids (I-IV) present absorption maxima in the UVB range with slight differences between them, while resveratrol-OMC structure-based hybrids (V-VIII) showed main absorption in the UVA range. Among RESV-OMC hybrids, compounds V and VI exhibited higher UV absorption intensity, and compound VIII stood out for its broad-spectrum coverage in our simulations. Furthermore, both in silico and in vitro analyses revealed that compounds VII and VIII exhibited the highest antioxidant activity, with compound I emerging as the most reactive antioxidant within RESV-AVO hybrids. The study suggests a preference for the hydrogen atom transfer (HAT) mechanism over single-electron transfer followed by proton transfer (SET-PT) in the gas phase. With a strong focus on sustainability, this approach reduces costs and minimizes effluent production in synthesis research, promoting the eco-friendly development of new sunscreen active ingredients. The SPARTAN'20 program was utilized for the geometry optimization and energy calculations of all compounds. Conformer distribution analysis was performed using the Merck molecular force field 94 (MMFF94), and geometry optimization was carried out using the parametric method 6 (PM6) followed by density functional theory (DFT/B3LYP/6-31G(d)). The antioxidant behavior of the hybrid compounds (I-VIII) was determined using the highest occupied molecular orbital (εHOMO) and the lowest unoccupied molecular orbital (εLUMO) energies, as well as the bond dissociation enthalpy (BDE), ionization potential (IP), and proton dissociation enthalpy (PDE) values, all calculated at the same level of structural optimization. TD-DFT study is carried out to calculate the excitation energy using the B3LYP functional with the 6-31G(d) basis set. The calculated transitions were convoluted with a Gaussian profile using the Gabedit program.

A modified pararosaniline hydrochloride method for determination of total and bound sulfur dioxide in wine

An improved pararosaniline hydrochloride (PRA) method for rapid and accurate determination of total and bound sulfur dioxide (SO2) in wine was established. The determination conditions for total SO2 were optimized in model wine systems. The pH of the acidified PRA reagent had a significant effect on the color and the maximum absorption wavelength (λmax) of the reaction system, with its optimum pH 0.48 and a λmax at 549 nm. The addition of ethylene diamine tetraacetic acid (EDTA) could effectively shield the interference of coexisting metal ions present in wine, and a novel approach to double background subtraction was confirmed to remove the matrices interference of red wine color. Under the optimum conditions, the linear range for total SO2 in wine was within 1.00–8.00 mg L−1 (R = 0.9975), with the detection and quantification limits (MDL and MQL) found as 0.02 and 0.06 mg L−1, respectively. The recovery of SO2 ranged from 85.73 % to 105.70 % with the relative standard deviations (RSD) of 0.21 % - 7.78 %, suggesting high sensitivity and accuracy of the method. Combining with the optimized Monier-Williams method, the determination of bound SO2 in wine was also achieved. Sulfite determination can be performed in wine using the rapid, accurate and sensitive method without any pretreatment, and the results were comparable with those of the standard methods.

Exploring the nonlinear optical characteristics of supersalt-decorated graphyne via DFT analysis: unveiling quantum insights into light-matter interaction

In this comprehensive study, we explore into the nonlinear optical (NLO) properties of graphyne (GRY) and its compounds decorated with a super salt (OLi3BeF3), namely GRY@SS1, and GRY@SS2) using the rB3LYP/6−31G(d,p) DFT method. Our findings reveal a substantial enhancement in the electron transfer properties of decorated compounds compared to the pristine GRY surface. This enhancement is evidence by the reduction in the bandgap energies (Eg) from 3.52 eV to 1.68 eV and remarkable boost in maximum absorption ( λmax) from 372.66 to 807.73 nm. Noteably, GRY@SS2 exhibits a significant increase in linear polarizability ( α0 ) (538.18 au), first hyperpolarizability ( β0 ) (3872.76 au), and second hyperpolarizability ( γ0 ) (1.00 × 106) due to reduced excitations energies compared to the GRY ( α0 = 448.61, β0 = 0.14 and γ0 = 5.97 × 105 au). NBO charges show that electrons are transferring from the dopant (supersalt) to the GRY sheet. Furthermore, Non-covalent interactions (NCl), iso-surface, infrared (IR), 1H NMR, and 13C NMR studies have been conducted to provide insights into the nature of interactions, vibrational frequencies, and structural-functional aspects of GRY and GRY@SS1, and GRY@SS2. According to TD-DFT calculations, all compounds demonstrate superior vertical ionization potential, UV–vis absorbance, HOMO–LUMO characteristics, as well as interaction energies. Our results underscore the potential of these compounds as valuable NLO materials, particularly highlighting the promising prospects of GRY@SS2.

Synthesis of Novel Acrylamide Graft Copolymer of Acacia nilotica Gum for the Stabilization of Melatonin Nanoparticles for Improved Therapeutic Effect: Optimization Using (3)2 Factorial Design.

The objective of the present study was to optimize the microwave-assisted synthesis of the acrylamide graft copolymer of Acacia nilotica gum (AM-co-ANG). Furthermore, graft copolymer was used for the formulation of a nanoparticulate system using a novel top to bottom solvent antisolvent technique for the delivery of melatonin. Grafting of ANG was optimized by using 32 factorial design, where concentrations of polymer and monomer (acrylamide) were used as independent variables and swelling index in acidic (0.1 N HCl) and basic (1 N NaOH) pH. Grafted polymers were further used to develop and optimize nanoparticulate system using concentration of the graft copolymer and concentration of drug as independent variables. The size of the nanoformulation and entrapment efficiency were selected as dependent variables. Difference in infrared spectrum and absorbance maxima in the ultraviolet region confirm that grafting has taken place. Porous structure and a higher contact angle confirmed hydrophobic nature of AM-co-ANG as compared with the native polymer. Acrylamide graft copolymers show more swelling in 1 N NaOH as compared with 0.1 N HCl. In vitro toxicity studies in hepatic (HepG2 cell line), brain (SHSY5Y cell line), and skin (HaCaT cell line) cells easily predict that synthesized polymer have no cytotoxicity. The entrapment efficiency ranged from 55.24 ± 1.35% to 73.21 ± 1.83%. A nonlinear correlation was observed between independent and dependent variables, as confirmed by multivariate analysis of variance, surface regression, and the correlation report. The prepared formulations were able to release drug up to 12 h. The regression coefficient easily predicted that most of the formulations followed Baker-Lonsdale drug release kinetics.

Carbon nanofiber aerogel microspheres with heterogeneous skin-core structure for broadband electromagnetic wave absorption

The advancement in the miniaturization of carbon aerogels into micro-sized spheres represents a significant development in the creation of ultralight, broadband microwave absorbers. Notwithstanding this innovation, there is still a considerable challenge in optimizing microwave absorption (MA) performance through heterointerface engineering within aerogel microspheres. Herein, we have developed skin-core heterogeneous aerogel microspheres by the in situ generation of ZIF-67 nanocrystals on the wet-spun aramid nanofiber (ANF) aerogel microspheres, followed by a high-temperature carbonization process. The resulting Co@C nanoparticle-enshrouded ANF-derived carbon nanofiber aerogel microspheres (Co@C/CNFAMs) demonstrate an exceptional equilibrium between impedance matching and multi-faceted attenuation. Remarkably, the Co@C/CNFAM2 sample attains a maximum effective absorption bandwidth of 8.72 GHz, while maintaining an ultralow filler proportion of 1.5 wt%. Moreover, the Co@C/CNFAM3 sample achieves a minimum reflection loss of −72.34 dB with a filling ratio of 1.2 wt%. Our findings offer a refined approach to the intricate engineering of heterostructures, along with the strategic macrostructural design, paving the way for the development of aerogel-based microwave absorbers that represent the next step in material science innovation.

Investigation of growth and polarized spectra of Ho3+ ions heavily doped BaY2F8 crystal

A BaY2F8 (BYF) single crystal heavily doped with Ho3+ ion was grown successfully using the Czochralski (Cz) method. The infrared fluorescence spectra (2–4 μm) and fluorescence lifetime at 3.9 μm were investigated. The detailed polarization absorption properties of Ho:BYF, especially the absorption spectrum in 850–950 nm range, were reported for the first time. The maximum absorption cross-section was at 888.15 nm, σabs = 1.26✕10−21 cm2 (E//c). In comparison, the peak positions of the absorption cross sections in the other two polarization directions were at 885.80 nm and 890.45 nm, respectively, indicating that incident light's polarization direction greatly influences absorption. The spectroscopic parameters were calculated based on the Judd–Ofelt theory.

Exploration of the synergistic effect of chrysene-based core and benzothiophene acceptors on photovoltaic properties of organic solar cells

To improve the efficacy of organic solar cells (OSCs), novel small acceptor molecules (CTD1–CTD7) were designed by modification at the terminal acceptors of reference compound CTR. The optoelectronic properties of the investigated compounds (CTD1–CTD7) were accomplished by employing density functional theory (DFT) in combination with time-dependent density functional theory (TD-DFT). The M06 functional along with a 6-311G(d,p) basis set was utilized for calculating various parameters such as: frontier molecular orbitals (FMO), absorption maxima (λmax), binding energy (Eb), transition density matrix (TDM), density of states (DOS), and open circuit voltage (Voc) of entitled chromophores. A red shift in the absorption spectra of all designed chromophores (CTD1–CTD7) was observed as compared to CTR, accompanied by low excitation energy. Particularly, CTD4 was characterized by the highest λmax value of 685.791 nm and the lowest transition energy value of 1.801 eV which might be ascribed to the robust electron-withdrawing end-capped acceptor group. The observed reduced binding energy (Eb) was linked to an elevated rate of exciton dissociation and substantial charge transfer from central core in HOMO towards terminal acceptors in LUMO. These results were further supported by the outcomes from TDM and DOS analyses. Among all entitled chromophores, CTD4 exhibited bathochromic shift (685.791 nm), minimum HOMO/LUMO band gap of 2.347 eV with greater CT. Thus, it can be concluded that by employing molecular engineering with efficient acceptor moieties, the efficiency of photovoltaic materials could be improved.

Physicochemical characterization of the brown pigment produced by Azospirillum brasilense HM053 using tryptophan as precursor.

Microorganisms are known to be a promising source of biopigments because they are easy to obtain, can be produced on a commercial scale, and are environmentally friendly. Therefore, the aim of this work was to characterize a brown pigment (BP) produced by HM053 in NFbHPN-lactate medium. The BP was extracted from the pellet (BPP) or supernatant (BPS), in the presence (BPPTrp, BPSTrp) or absence (BPPw, BPSw) of tryptophan (Trp). The UV-vis results were similar among all BP samples and compared with commercial melanin used as a standard, and the maximum absorption was observed around 200-220nm. FTIR spectra showed that BP and commercial melanin had slight differences, with a small band between 3000-2840cm- 1, related to C-H in the CH2 and CH3 aliphatic groups, which is not observed in the commercial melanin. Between BPP and BPS showed a different structure with bands in the region 1230-1070cm- 1 related to groups C-O. The thermogravimetric curves for BPSw and BPSTrp showed similar behavior, with 4 stages of mass loss. The similarity between BPPw and BPPTrp with 2 stages of mass loss was also observed. Scanning electron microscopy results showed morphological differences between BPP and BPS, where BPP had a physical structure more homogeneous and a regular flat surface, while the BPS physical structure did not seem homogeneous and the surface was uneven with some spherical structures as commercial melanin.

Quantum Computational and Spectroscopic Investigation of 3-aminosalicylic Acid.

Quantum chemical calculations of3-aminosalicylic acid (3ASA) (monomer and dimer forms) have been performed using DFT and TD-DFT theories with B3LYP/6-311 G(d,p) functional level in the ground and excited states. Using TD-DFT with IEF-PCM model, the electronic spectra of 3ASA in solvents were computed and correlated with the experimental data. The theoretically calculated absorption and emission maxima of 3ASA (monomer) are observed in the range of 343- 347nm (S0 → S1 transition) and 429- 448nm (S1 → S0 transition), respectively. The natural bond orbital (NBO) analysis shows that charge transfer interaction contributes significantly to stabilize the molecular system. In the case of dimer, hydrogen bonding plays a dominant role in stabilizing the molecular framework. Additionally, the obtained nonlinear optical (NLO) properties: polarizability (13.86 × 10-24 e.s.u for monomer and 29.46 × 10-24 e.s.u. for dimer), first-order hyperpolarizability (4.21 × 10-30 e.s.u for monomer and 0.18 × 10-30 e.s.u for dimer) and second-order hyperpolarizability (7.44 × 10-36 e.s.u. for monomer and 14.32 × 10-36 e.s.u. for dimer) were found to be larger than those of standard organic compounds suggesting that 3ASA has a significant NLO character for optoelectronic applications. The NLO properties of dimer may differ from monomer due to dimerization. Further, the radiative lifetime, light harvesting efficiency and band gap energy were calculated, and proposed that 3ASA may be useful in photovoltaics and wide bandgap power devices. HIGHLIGHTS: • DFT and TD-DFT theories were employed to calculate structural and molecular properties of 3ASA (monomer and dimer) in ground and excited states. • HOMO-LUMO study shows monomer and dimer of 3ASA are good reactive. • NBO analysis reflects that charge transfer interactions stabilized the 3ASA molecule. • Electronic absorption/emission spectra in solvents calculated by IEF-PCM/TD-DFT method correlate with experimental results. • Calculated NLO parameters suggested that 3ASA is a potential candidate for NLO material.

Pyrobacteriopheophorbide-a derivatives possessing various hydrophilic esterifying groups at the C17-propionate residues for photodynamic therapy.

Aiming at the application to photodynamic therapy, natural bacteriochlorophyll-a was converted to chemically stable free-base derivatives possessing different kinds of hydrophilic C17-propionate residues. These semi-synthetic bacteriochlorins were found to have self-assembling ability in an aqueous environment and formed stable J-type aggregates in a cell culture medium containing 0.2% DMSO. The electronic absorption spectra of all the sensitizers showed Qy absorption maxima at 754 nm in DMSO as their monomeric states, while a drastic shift of the red-most bands to ca. 880 nm was observed in the aqueous medium. The circular dichroism spectra in the medium showed much intense signals compared to those measured in DMSO, supporting the formation of well-ordered supramolecular structures. By introducing hydrophilic side chains, the bacteriochlorin sensitizers could be dispersed in the aqueous medium as their J-aggregates without the use of any surfactants. Cellular uptake efficiencies as well as photodynamic activities were evaluated using human cervical adenocarcinoma HeLa cells. Among the 11 photosensitizers investigated, the best result was obtained for a charged derivative possessing trimethylammonium terminal (17-CH2CH2COOCH2CH2N+(CH3)3I-) and photocytotoxicity of EC50 = 0.09 μM was achieved by far-red light illumination of 35 J/cm2 from an LED panel (730 nm).

Comparison of physical and mechanical properties of traditional bricks in Deli Serdang with no-burn bricks using rice husk ash

Population growth has increased, causing more and more housing needs; Indonesia is one of the countries where bricks are still used as the primary material in building walls. It has resulted in increased demand for bricks. One of Indonesia’s regions, Deli Serdang Regency, produces traditional bricks that burn a lot, but the process of making traditional bricks can cause environmental pollution. This research aims to find a way to reduce the effects of environmental pollution by making pressed bricks without burning and utilizing agricultural waste, namely rice husk ash (RHA). After that, a comparison was made between traditional burnt bricks from 15 sub-districts in Deli Serdang Regency and unburnt bricks made from rice husk ash (RHA). This study uses two methods, namely the method of sampling burned bricks and the method of making bricks without burning, both of which are tested for physical and mechanical properties. The results of this study use the requirements of SNI 15-2094-2000, where the test of physical properties of fuel bricks obtained a value of 76%, which meets the requirements, while bricks without burning obtained a value of 87.5%, which meets the requirements. For the results of the size of fuel bricks obtained, 66.6% of the value meets the requirements, while for bricks without burning, 100% meet the requirements. Mechanical properties test for absorption testing on fuel bricks obtained 0.135% while unburned bricks 0.130%, where the value meets the SNI requirements of a maximum absorption of 20%. Salt content testing obtained a value of 0.15% for burned bricks and 0.002% for unburned bricks, where the value meets the SNI requirements that are below 50%. Testing the compressive strength of bricks with a standard value of 5 MPa from the test results of the compressive strength of fuel bricks 3.01 MPa decreased by 39.8%, while the test of compressive strength of unburned bricks 5.17 MPa increased by 3.45%, but unburned bricks with added rice husk ash 1.98 MPa decreased by 60.4%. Based on the study’s results, the absorption and salt content parameters follow the standard. At the same time, the strength test of firebricks and unburned bricks with added rice husk ash does not meet the SNI 15-2094-2000 standard, but the results of the compressive strength test of unburned bricks meet the SNI 15-2094-2000 standard.

Spontaneous emission, collective phenomena and the efficiency of plasmon-stimulated photoexcitation

We find that the spontaneous and collective emissions have a strong influence on the excitation of two-level absorbers (atoms, molecules) interacting in resonance with the plasmonic mode near the metal nanoparticle. The spontaneous and collective emissions limit the absorption enhancement by the plasmonic mode and make the enhancement possible only with a fast, picosecond population relaxation of the upper absorbing states. Conditions for the maximum of plasmon-enhanced absorption in the presence of spontaneous and collective emissions are found. The nonlinearity in the nanoparticle-absorber interaction and in collective emission causes the bistability in the plasmon-enhanced absorption at high external field intensities and the plasmonic mode excitation.

Comparative Analysis of Water-Induced Response in 3D-Printed SCF/ABS Composites under Controlled Diffusion

Additive manufacturing (AM) or 3D-printing of fiber-reinforced composites (FRCs) has garnered significant interests for its versatility in creating intricate parts and rapid prototyping due to cost-effectiveness. Although short fiber-reinforced thermoplastic composites are challenging to manufacture, their mechanical properties can be easily tailored by adjusting fiber type, orientation, and volume fraction. However, void formation during printing is a key issue, impacting mechanical properties and facilitating water ingression, affecting long-term durability. This work studies water diffusion characteristics and the associated hydro-aging of 3D-printed short carbon fiber (SCF)/acrylonitrile butadiene styrene (ABS) composites with controlled water diffusion. Effects of material type (ABS and SCF/ABS), 3D-printing path (horizontal and vertical filament orientation), and diffusion surface (uni-directional and bi-directional diffusion) on water diffusion coefficient and maximum water absorption level are characterized to ensure the long-term durability of 3D-printed ABS and SCF/ABS composites. Baseline representative volume element-based finite element (RVE-FE) diffusion models were developed based on micro-computed tomography (micro-CT) image analysis to understand water diffusion characteristics. This work proves that the SCF/ABS composite is more resistive to hydro-aging than neat ABS due to the SCFs’ hydrophobic nature. SCF/ABS composites, while providing distinct advantages over pure ABS in terms of mechanical properties, could also be more effective against water environments.