Tutorial on methods for estimation of optical absorption and scattering properties of tissue

Significance

The estimation of tissue optical properties using diffuse optics has found a range of applications in disease detection, therapy monitoring, and general health care. Biomarkers derived from the estimated optical absorption and scattering coefficients can reflect the underlying progression of many biological processes in tissues.

Aim

Complex light-tissue interactions make it challenging to disentangle the absorption and scattering coefficients, so dedicated measurement systems are required. We aim to help readers understand the measurement principles and practical considerations needed when choosing between different estimation methods based on diffuse optics.

Approach

The estimation methods can be categorized as: steady state, time domain, time frequency domain (FD), spatial domain, and spatial FD. The experimental measurements are coupled with models of light-tissue interactions, which enable inverse solutions for the absorption and scattering coefficients from the measured tissue reflectance and/or transmittance.

Results

The estimation of tissue optical properties has been applied to characterize a variety of ex vivo and in vivo tissues, as well as tissue-mimicking phantoms. Choosing a specific estimation method for a certain application has to trade-off its advantages and limitations.

Conclusion

Optical absorption and scattering property estimation is an increasingly important and accessible approach for medical diagnosis and health monitoring.

Absorption of 5G sub-6 GHz electromagnetic radiation from base station to male reproduction system

BACKGROUND

The impact of electromagnetic radiation from communication on the male reproductive system has emerged as a significant concern in public health. A notable distinction of the 5G sub-6 GHz band, compared to traditional 2G, 3G, and 4G frequency bands, is the inclusion of higher frequency bands. This has raised public concerns regarding the potential effects of these higher frequencies on organisms, particularly their reproductive systems. While it is imperative to investigate the biological effects and potential risks associated with these new frequency bands in laboratory settings, comparing and evaluating differences between various frequency bands remain challenging due to the absence of standardized parameters such as exposure conditions and duration. In contrast, dose assessment offers a simpler and more reliable approach.

MATERIALS AND METHODS

The dose assessment method was employed in this study to investigate the risks associated with sub-6 GHz electromagnetic radiation from 5G base stations on the male reproductive system. A classical human body model (Duke) was utilized, and an electromagnetic simulation environment was established based on the actual polarization direction of the exposed base stations and various body postures. This research explored the effects of field direction, posture, public population, and frequency on the specific absorption rate of the reproductive system.

RESULTS AND CONCLUSIONS

While maintaining the same level of exposure, a higher frequency results in a reduced dosage on reproductive system. Further analysis reveals that, considering the public exposure threshold, the employment of higher frequency bands in 5G sub-6 GHz does not present a greater dosage on reproductive system compared to lower frequency bands. Consequently, with regard to dosage, there is no need for excessive concern among the general public regarding the impact of electromagnetic radiation emitted by 5G base stations operating below 6 GHz on male reproductive health.

Electromagnetic interference shielding of flexible carboxymethyl cellulose/MWCNT@Fe3O4 composite film with ultralow reflection loss

Nowadays, various high-performance electromagnetic interference (EMI) shielding materials have enormous application potential in electronic field. However, traditional EMI shielding materials often have high conductivity, resulting in the serious mismatch between the impedance of the material surface and the free space, which will cause a large amount of reflection of electromagnetic (EM) waves, leading to secondary reflection pollution. In this paper, we report a novel flexible EMI shielding composite film with extremely low reflection loss and efficient EM wave absorption, which was prepared by assisted self-assembly based on simple vacuum filtration using carboxymethyl cellulose as the matrix and MWCNT@Fe3O4 synthesized by chemical coprecipitation as the composite functional filler. By adjusting the Fe3O4 coating degree of MWCNTs in the filler, the composite film achieved the construction of a conductive network with high Fe3O4 content. Benefit by the good adaptability of conductivity and magnetic permeability, the composite film has good impedance matching ability and microwave absorption performance. The reflection loss of the composite film with the thickness of 28 μm in the X-band was only 0.23 dB, accounting for 1.7 % of the total loss. This work provides new insights for the development of EMI materials and effective mitigation secondary EM wave reflection pollution.

Immunogenic Radiation Therapy for Enhanced Antitumor Immunity via a Core-Shell Nanosensitizer-Mediated Immunosuppressive Tumor Microenvironment Modulation

Due to the immunosuppressive tumor microenvironment (TME) and weak radiation absorption, the immune response triggered by radiation therapy (RT) is limited. Herein, a core-shell nanosensitizer UiO@MnS (denoted as UM) was genuinely constructed for the amplification of RT efficacy and induction of immunogenicity via integrating MnS-reprogrammed TME with Hf-based UiO-sensitized RT. The acid-sensitive MnS would produce H2S under acidic TME to improve oxygenation through inhibition mitochondrial respiration and reducing metabolic oxygen consumption, leading to decreased HIF-1α expression and enhanced radiosensitization. In addition, the generated H2S inhibited the catalase activity to increase the H2O2 level, which subsequently enhanced the Mn2+-mediated Fenton-like reaction, resulting in G2/M cell cycle arrest to improve the cellular sensitivity for radiation. This impressive tumor oxygenation, cell cycle arrest, and radiosensitization procedure boosted RT efficacy and resulted in strong antitumor immunogenicity. Taken together, combining the immunosuppressive TME modulation with a sensitizing radiation strategy shows great promise for magnifying immunogenic RT outputs.

Development of a charged model of the SARS-CoV-2 viral surface

A recent study provided experimental evidence of inactivation of viral activity after radio-frequency (RF) exposures in the 6-12 GHz band that was hypothesized to be caused by vibrations of an acoustic dipole mode in the virus that excited the viral membrane to failure. Here, we develop an atomic-scale molecular dynamics (MD) model of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral surface to estimate the electric fields necessary to rupture the viral membrane via dipole shaking of the virus. We computed the absorption spectrum of the system via unbiased MD simulations and found no particular strong absorption in the GHz band. We investigated the mechanical resiliency of the viral membrane by introducing uniaxial strains in the system and observed no pore formation in the membrane for strains up to 50%. Because the computed absorption spectrum was found to be essentially flat, and the strain required to break the viral membrane was >0.5, the field strength associated with rupture of the virus was greater than the dielectric breakdown value of air. Thus, RF disinfection of enveloped viruses would occur only once sufficient heat was transferred to the virus via a thermal mechanism and not by direct action (shaking) of the RF field oscillations on the viral membrane.

Core-Shell Structured SiO2@NiFe LDH Composite for Broadband Electromagnetic Wave Absorption

In this work, a novel core-shell structure material, NiFe layered double hydroxide (NiFe LDH) loaded on SiO2 microspheres (SiO2@NiFe LDH), was synthesized by a one-step hydrothermal method, and the spontaneous electrostatic self-assembly process. The morphology, structure, and microwave absorption properties of SiO2@NiFe LDH nanocomposites with different NiFe element ratios were systematically investigated. The results show that the sample of SiO2@NiFe LDH-3 nanocomposite has excellent microwave absorption properties. It exhibits broadband effective absorption bandwidth (RL < −10 dB) of 8.24 GHz (from 9.76 GHz to 18.0 GHz) and the reflection loss is −53.78 dB at the matched thickness of 6.95 mm. It is expected that this SiO2@NiFe-LDH core-shell structural material can be used as a promising non-precious, metal-based material microwave absorber to eliminate electromagnetic wave contamination.

Physicochemical, antioxidant properties of carotenoids and its optoelectronic and interaction studies with chlorophyll pigments

The physicochemical and antioxidant properties of seven carotenoids: antheraxanthin, β-carotene, neoxanthin, peridinin, violaxanthin, xanthrophyll and zeaxanthin were studied by theoretical means. Then the Optoelectronic properties and interaction of chlorophyll-carotenoid complexes are analysed by TDDFT and IGMPLOT. Global reactivity descriptors for carotenoids and chlorophyll (Chla, Chlb) are calculated via conceptual density functional theory (CDFT). The higher HOMO-LUMO (HL) gap indicated structural stability of carotenoid, chlorophyll and chlorophyll-carotenoid complexes. The chemical hardness for carotenoids and Chlorophyll is found to be lower in the solvent medium than in the gas phase. Results showed that carotenoids can be used as good reactive nucleophile due to lower µ and ω. As proton affinities (PAs) are much lower than the bond dissociation enthalpies (BDEs), it is anticipated that direct antioxidant activity in these carotenoids is mainly due to the sequential proton loss electron transfer (SPLET) mechanism with dominant solvent effects. Also lower PAs of carotenoid suggest that antioxidant activity by the SPLET mechanism should be a result of a balance between proclivities to transfer protons. Reaction rate constant with Transition-State Theory (TST) were estimated for carotenoid-Chlorophyll complexes in gas phase. Time dependent Density Functional Theory (TDDFT) showed that all the chlorophyll (Chla, Chlb)-carotenoid complexes show absorption wavelength in the visible region. The lower S1-T1 adiabatic energy gap indicated ISC transition from S1 to T1 state.

3D printing fluorescent material with tunable optical properties

The 3D printing of fluorescent materials could help develop, validate, and translate imaging technologies, including systems for fluorescence-guided surgery. Despite advances in 3D printing techniques for optical targets, no comprehensive method has been demonstrated for the simultaneous incorporation of fluorophores and fine-tuning of absorption and scattering properties. Here, we introduce a photopolymer-based 3D printing method for manufacturing fluorescent material with tunable optical properties. The results demonstrate the ability to 3D print various individual fluorophores at reasonably high fluorescence yields, including IR-125, quantum dots, methylene blue, and rhodamine 590. Furthermore, tuning of the absorption and reduced scattering coefficients is demonstrated within the relevant mamalian soft tissue coefficient ranges of 0.005-0.05 mm-1 and 0.2-1.5 mm-1, respectively. Fabrication of fluorophore-doped biomimicking and complex geometric structures validated the ability to print feature sizes less than 200 μm. The presented methods and optical characterization techniques provide the foundation for the manufacturing of solid 3D printed fluorescent structures, with direct relevance to biomedical optics and the broad adoption of fast manufacturing methods in fluorescence imaging.

Determination of the characteristic inactivation fluence for SARS-CoV-2 under UV-C radiation considering light absorption in culture media

The optical absorption coefficient of culture media is critical for the survival analysis of pathogens under optical irradiation. The quality of the results obtained from experiments relies on the optical analysis of the spatial distribution of fluence which also depends on the geometry of the sample. In this contribution, we consider both the geometrical shape and the culture medium's absorption coefficient to evaluate how the spatial distribution of optical radiation affects pathogens/viruses. In this work, we exposed SARS-CoV-2 to UV-C radiation ([Formula: see text] = 254 nm) and we calculated-considering the influence of the optical absorption of the culture medium-a characteristic inactivation fluence of [Formula: see text] = 4.7 J/m2, or an equivalent 10% survival (D90 dose) of 10.8 J/m2. Experimentally, we diluted the virus into sessile drops of Dulbecco's Modified Eagle Medium to evaluate pathogen activity after controlled doses of UV irradiation. To validate the optical absorption mode, we carried out an additional experiment where we varied droplet size. Our model-including optical absorption and geometrical considerations-provides robust results among a variety of experimental situations, and represents our experimental conditions more accurately. These results will help to evaluate the capability of UV disinfecting strategies applied to a variety of everyday situations, including the case of micro-droplets generated by respiratory functions.

SAR and temperature distributions in a database of realistic human models for 7 T cardiac imaging

PURPOSE

To investigate inter-subject variability of B₁⁺ , SAR and temperature rise in a database of human models using a local transmit array for 7 T cardiac imaging.

METHODS

Dixon images were acquired of 14 subjects and segmented in dielectric models with an eight-channel local transmit array positioned around the torso for cardiac imaging. EM simulations were done to calculate SAR distributions. Based on the SAR distributions, temperature simulations were performed for exposure times of 6 min and 30 min. Peak local SAR and temperature rise levels were calculated for different RF shim settings. A statistical analysis of the resulting peak local SAR and temperature rise levels was performed to arrive at safe power limits.

RESULTS

For RF shim vectors with random phase and uniformly distributed power, a safe average power limit of 35.7 W was determined (first level controlled mode). When RF amplitude and phase shimming was performed on the heart, a safe average power limit of 35.0 W was found. According to Pennes' model, our numerical study suggests a very low probability of exceeding the absolute local temperature limit of 40 °C for a total exposure time of 6 min and a peak local SAR of 20 W/kg. For a 30 min exposure time at 20 W/kg, it was shown that the absolute temperature limit can be exceeded in the case where perfusion does not change with temperature.

CONCLUSION

Safe power constraints were found for 7 T cardiac imaging with an eight-channel local transmit array, while considering the inter-subject variability of B₁⁺ , SAR and temperature rise.

A Halomanganates(II) with P,P'-Diprotonated Bis(2-Diphenylphosphinophenyl)ether: Wavelength-Excitation Dependence of the Quantum Yield and Role of the Non-Covalent Interactions

A [H2DPEphos][MnX4] [X = Br, Cl] tetrahalomanganates(II) with P,P'-diprotonated bis[2-(diphenylphosphino)phenyl]ether cation has been designed and investigated in photophysics and EPR terms. The complexes exhibit a green luminescence resulted from the Mn(II) d-d transitions (4T1→6A1) with the wavelength-excitation dependence of the quantum yield. The solid [H2DPEphos][MnBr4] complex exhibits a bright green phosphorescence (λmax = 515 nm) with the high luminescence quantum yield depending on the excitation energy whereas the solid [H2DPEphos][MnCl4] complex exhibits a very weak phosphorescence (λmax = 523 nm). The unexpected shorter luminescence lifetime for the [H2DPEphos][MnCl4] than for the [H2DPEphos][MnBr4] at 300 K can be a result of the higher non-radiative relaxation contribution. On the one hand, the non-covalent PH…X(Mn) interactions quench the manganese(II) luminescence. On the other hand, the PH…X(Mn) interactions are a pathway of the excitation transfer from [H2DPEphos]2+ to [MnX4]2-.

Reaction kinetics formulation with explicit radiation absorption effects of the photo-Fenton degradation of paracetamol under natural pH conditions

The degradation of paracetamol (PCT) in an aqueous medium using the Fenton and photo-Fenton reactions was investigated. The aim of this research was the development of a kinetic model based on a reaction mechanism, which includes two main intermediates of PCT degradation and the local volumetric rate of photon absorption (LVRPA). Ferrioxalate was used as a catalyst and the working pH was adjusted to 5.5 (natural pH). Experimental work was planned through a D-optimal experimental design and performed in a flat plate reactor irradiated by a solar simulator. Hydrogen peroxide (HP) concentration, reaction temperature, and radiation level were the operating parameters. The photo-Fenton reaction allowed to reach a minimum relative PCT concentration of 2.01% compared to 5.04% achieved with Fenton reaction. Moreover, the photo-Fenton system required a 50% shorter reaction time and lower HP concentration than in dark conditions (90 min and 189 mg L^-1 vs. 180 min and 334 mg L^-1, respectively). The experimental results were used to estimate the kinetic parameters of the proposed kinetic model employing a nonlinear, multi-parameter regression method. The values obtained from the normalized root-mean-square error (14.52, 1.96, 4.36, 13.16, and 8.72 % for PCT, benzoquinone, hydroquinone, HP, and oxalate, respectively) showed a good agreement between the predicted and experimental data.

Catechin-grafted arabinoxylan conjugate: Preparation, structural characterization and property investigation

In this study, a high molecular weight arabinoxylan (AX, Mw: 694 kDa) from wheat bran was alkaline extracted and covalently linked with Catechin (CA) by free radical catalytic reaction. Comparing to AX, arabinoxylan-catechin (AX-CA) conjugates demonstrated an extra UV-vis absorption peak at 274 nm, a new FT-IR absorption band at 1516 cm^-1 and new proton signals at 6.5-7.5 ppm, which all confirmed the covalently linked structure. Grafting CA onto AX not only decreased the molecular weight, thermal stability and apparent viscosity of AX, but also enhanced its inhibition effects on starch digestibility in vitro. The in vitro fermentation test with pig feces showed that the degradation & utilization rate of AX, the total short-chain fatty acid (SCFA) and acetic acid levels produced all were significantly delayed after grafting. This study provided a novel approach to synthesize AX-CA conjugates that could be a novel dietary fiber of enhanced functional/bioactive properties using in the fields of functional foods and medicine.

Photodynamic and Sonodynamic Therapy with Protoporphyrin IX: In Vitro and In Vivo Studies

Sono-photodynamic therapy is a promising anticancer technique based on the combination of sonodynamic and photodynamic therapy to improve the cancer treatment effectiveness. This study was aimed at analyzing the effects of the sono-photodynamic (SPD) activity on protoporphyrin IX (PpIX) solution and PpIX-loaded rat liver. In vitro, PpIX 5 μM solutions were irradiated with light (635 nm, 30-50 mW/cm²), ultrasound (1 MHz, 1-2 W/cm²) and both. The PpIX absorption spectra recorded over exposure time revealed that the PpIX decay rate induced by SPD activity (combined irradiation) was approximately the sum of those induced by photodynamic and sonodynamic activity. In vivo, rats were intraperitoneally injected with 5-aminolevulinic acid at the dose of 500 mg/kg weight. After 3 h of injection, the PpIX-loaded livers were irradiated with light (635 nm, 180 ± 9 J/cm²), ultrasound (1.0 MHz, 770 ± 40 J/cm²) and both using a single probe capable of illuminating and sonicating the liver simultaneously. After 30 h, the liver damage induced by each protocol was analyzed histologically. It was found that a greater necrosis depth was induced by the SPD activity. These results suggest that the SPD activity could improve the PpIX decay rate and have greater scope than photodynamic or sonodynamic activity. Further studies should be performed to gain a better understanding of this protocol.

Label-Free Multiphoton Microscopy: Much More Than Fancy Images

Multiphoton microscopy has recently passed the milestone of its first 30 years of activity in biomedical research. The growing interest around this approach has led to a variety of applications from basic research to clinical practice. Moreover, this technique offers the advantage of label-free multiphoton imaging to analyze samples without staining processes and the need for a dedicated system. Here, we review the state of the art of label-free techniques; then, we focus on two-photon autofluorescence as well as second and third harmonic generation, describing physical and technical characteristics. We summarize some successful applications to a plethora of biomedical research fields and samples, underlying the versatility of this technique. A paragraph is dedicated to an overview of sample preparation, which is a crucial step in every microscopy experiment. Afterwards, we provide a detailed review analysis of the main quantitative methods to extract important information and parameters from acquired images using second harmonic generation. Lastly, we discuss advantages, limitations, and future perspectives in label-free multiphoton microscopy.

Can Photons Pass through Primary Coatings Used to Treat Cutaneous Wounds?

OBJECTIVE

To determine the transmittance spectrum of primary dressings commonly used in the treatment of cutaneous wounds to verify if there is a real need to remove them during photobiomodulation.

METHODS

Spectroscopic analysis was performed on 17 dressings using a spectrophotometer (USB 2000+; OceanOptics, Delray Beach, Florida). A piece of each dressing was inserted into a quartz cuvette; the reflection from the slide walls was corrected for using a 0.9% saline solution to completely fill the cuvette (baseline). The transmittance of each dressing was measured between 350 and 950 nm, and a transmittance table was created based on the main wavelengths used in photobiomodulation.

RESULTS

Six dressings (Supriderme, Membracel, Cuticell Contact, UrgoTul, Tegaderm, and Opsite Flexigrid) have a transmittance greater than 50% in most of the spectral range and therefore may remain on wounds during irradiation.

CONCLUSIONS

It may not always be necessary to remove a primary dressing when lasers or LED lights are used to treat wounds. It is the authors' hope that the results of this article will increase the effectiveness of both photobiomodulation and primary dressings and reduce patient discomfort as well as the cost of primary dressings via a reduction in unnecessary dressing changes.

Hydrogen-rich water attenuates the radiotoxicity induced by tritium exposure in vitro and in vivo

Radionuclide tritium is widely used in the nuclear energy production industry and creates a threat to human health through radiation exposure. Herein, the radioactive elimination and radioprotective effect of hydrogen-rich water (HRW), a potential antioxidant with various medical applications, on tritiated water (HTO) exposure, was studied in vitro and in vivo. Results showed that intragastric administration of HRW effectively promoted the elimination of urinary tritium, decreased the level of serum tritium and tissue-bound tritium (OBT), and attenuated the genetic damage of blood cells in mice exposed to HTO (18.5 MBq/kg). Pretreatment with HRW effectively reduces tritium accumulation in HTO-treated human blood B lymphocyte AHH-1 cells. In addition, the anti-oxidative properties of HRW could attenuate the increased intracellular ROS (such as O2•-, •OH and ONOO-), resulting in reversing the exhaustion of cellular endogenous antioxidants (reduced GSH and SOD), decreasing lipid peroxidation (MDA), relieving DNA oxidative damage, and depressing cell apoptosis and cytotoxicity induced by HTO exposure. In conclusion, HRW is expected to be an effective radioactive elimination agent through the competition effect of isotope exchange or a radioprotective agent by scavenging free radicals induced by HTO exposure.

Nanometer optical trap based on stimulated emission in evanescence of a totally reflected Arago spot : Nanometer optical trap for fluorescent nanoparticles

Optical tweezers have paved the way towards the manipulation of particles and living cells at the micrometer range. Its extension towards the nanometer world may create unprecedented potentialities in many areas of science. Following a letter (O. Emile, J. Emile, H. Tabuteau, EPL 129, 58001 (2020)) that reported the observation of the trapping of a single 200nm diameter fluorescent particle in a nanometric volume, we detail here our experimental findings. In particular, the trapping mechanism is shown to be based on the radiation pressure of light in one direction and on the stimulated emission of the particle in the evanescent wave of a nanometer Arago spot on a glass/liquid interface on the other directions. The trapping volume is a 200nm height cylinder whose radius varies with the spreading of the evanescent wave near the spot and can reach 50nm. The calculation of the force and the parameters limiting the lifetime are detailed. Applications to laser trapping of atoms and molecules are also discussed.

Classification, identification, and growth stage estimation of microalgae based on transmission hyperspectral microscopic imaging and machine learning

A transmission hyperspectral microscopic imager (THMI) that utilizes machine learning algorithms for hyperspectral detection of microalgae is presented. The THMI system has excellent performance with spatial and spectral resolutions of 4 µm and 3 nm, respectively. We performed hyperspectral imaging (HSI) of three species of microalgae to verify their absorption characteristics. Transmission spectra were analyzed using principal component analysis (PCA) and peak ratio algorithms for dimensionality reduction and feature extraction, and a support vector machine (SVM) model was used for classification. The average accuracy, sensitivity and specificity to distinguish one species from the other two species were found to be 94.4%, 94.4% and 97.2%, respectively. A species identification experiment for a group of mixed microalgae in solution demonstrates the usability of the classification method. Using a random forest (RF) model, the growth stage in a phaeocystis growth cycle cultivated under laboratory conditions was predicted with an accuracy of 98.1%, indicating the feasibility to evaluate the growth state of microalgae through their transmission spectra. Experimental results show that the THMI system has the capability for classification, identification and growth stage estimation of microalgae, with strong potential for in-situ marine environmental monitoring and early warning detection applications.

Short-wavelength-sensitive 2 (Sws2) visual photopigment models combined with atomistic molecular simulations to predict spectral peaks of absorbance

For many species, vision is one of the most important sensory modalities for mediating essential tasks that include navigation, predation and foraging, predator avoidance, and numerous social behaviors. The vertebrate visual process begins when photons of the light interact with rod and cone photoreceptors that are present in the neural retina. Vertebrate visual photopigments are housed within these photoreceptor cells and are sensitive to a wide range of wavelengths that peak within the light spectrum, the latter of which is a function of the type of chromophore used and how it interacts with specific amino acid residues found within the opsin protein sequence. Minor differences in the amino acid sequences of the opsins are known to lead to large differences in the spectral peak of absorbance (i.e. the λmax value). In our prior studies, we developed a new approach that combined homology modeling and molecular dynamics simulations to gather structural information associated with chromophore conformation, then used it to generate statistical models for the accurate prediction of λmax values for photopigments derived from Rh1 and Rh2 amino acid sequences. In the present study, we test our novel approach to predict the λmax of phylogenetically distant Sws2 cone opsins. To build a model that can predict the λmax using our approach presented in our prior studies, we selected a spectrally-diverse set of 11 teleost Sws2 photopigments for which both amino acid sequence information and experimentally measured λmax values are known. The final first-order regression model, consisting of three terms associated with chromophore conformation, was sufficient to predict the λmax of Sws2 photopigments with high accuracy. This study further highlights the breadth of our approach in reliably predicting λmax values of Sws2 cone photopigments, evolutionary-more distant from template bovine RH1, and provided mechanistic insights into the role of known spectral tuning sites.

Shielding effect of radiation dose reduction fiber during the use of C-arm fluoroscopy: a phantom study

This study evaluated the shielding effect of a newly developed dose-reduction fiber (DRF) made from barium sulfate, in terms of radiation doses delivered to patients' radiosensitive organs and operator during C-arm fluoroscopy and its impact on the quality of images. A C-arm fluoroscopy unit was placed beside a whole-body phantom. Radiophotoluminescent glass dosimeters were attached to the back and front of the whole-body phantom at 20 cm intervals. Radiation doses were measured without DRF and with it applied to the back (position 1), front (position 2) or both sides (position 3) of the phantom. To investigate the impact of DRF on the quality of fluoroscopic images, step-wedge and modulation transfer function phantoms were used. The absorbed radiation doses to the back of the phantom significantly decreased by 25.3-88.8% after applying DRF to positions 1 and 3. The absorbed radiation doses to the front of the phantom significantly decreased by 55.3-93.6% after applying DRF to positions 2 and 3. The contrast resolution values for each adjacent step area fell in the range 0.0119-0.0209, 0.0128-0.0271, 0.0135-0.0339 and 0.0152-0.0339 without and with DRF applied to positions 1, 2 and 3, respectively. The investigated DRF effectively reduces absorbed radiation doses to patients and operators without decreasing the quality of C-arm fluoroscopic images. Therefore, routine clinical use of the DRF is recommended during the use of C-arm fluoroscopy.

Ali M, Sitther V, Ahammad AJS, Subhan MA, Uddin J. Enhancing the Performance of Dye Sensitized Solar Cells Using Silver Nanoparticles Modified Photoanode

In this study, silver nanoparticles were synthesized, characterized, and applied to a dye-sensitized solar cell (DSSC) to enhance the efficiency of solar cells. The synthesized silver nanoparticles were characterized with UV-Vis spectroscopy, dynamic light scattering, transmission electron microscopy, and field emission scanning electron microscopy. The silver nanoparticles infused titanium dioxide film was also characterized by Fourier transform infrared and Raman spectroscopy. The performance of DSSC fabricated with silver nanoparticle-modified photoanode was compared with that of a control group. The current and voltage characteristics of the devices as well as the electrochemical impedance measurements were also carried out to assess the performance of the fabricated solar cells. The solar-to-electric efficiency of silver nanoparticles based DSSC was 1.76%, which is quite remarkable compared to the 0.98% realized for DSSC fabricated without silver nanoparticles.

Decreasing undesirable absorbed radiation to the intestine after administration of radium-223 dichloride for treatment of bone metastases

[223Ra]RaCl2 is the first alpha-particle emitting radiopharmaceutical to be used for castration-resistant prostate cancer patients with bone metastases because of its excellent therapeutic effects. [223Ra]RaCl2 is excreted via the intestine into feces, and some is absorbed from the intestine into the blood, which may be undesirable in terms of the exposure to radiation. Recently, we showed that a complex of myo-inositol-hexakisphosphate (InsP6) with zinc is a useful decorporation agent against radiostrontium. In this study, we hypothesized that Zn-InsP6 could bind to not only strontium but also to radium, and could inhibit the absorption of radium from the intestine. In in vitro binding experiments, Zn-InsP6 showed a high binding affinity for radium. In in vivo biodistribution experiments by intravenous injection of [223Ra]RaCl2 after treatment of Zn-InsP6, mice treated with Zn-InsP6 showed significantly lower bone accumulation of radioactivity (34.82 ± 1.83%Dose/g) than the mice in the non-treatment control group (40.30 ± 2.78%Dose/g) at 48 h postinjection. These results indicate that Zn-InsP6 bound radium in the intestine and inhibited the absorption of radium into the blood. Therefore, the insoluble Zn-InsP6 complex has high potential to decrease the side effects of [223Ra]RaCl2.

Genetically encoded betaxanthin-based small-molecular fluorescent reporter for mammalian cells

We designed and engineered a dye production cassette encoding a heterologous pathway, including human tyrosine hydroxylase and Amanita muscaria 4,5-DOPA dioxygenase, for the biosynthesis of the betaxanthin family of plant and fungal pigments in mammalian cells. The system does not impair cell viability, and can be used as a non-protein reporter system to directly visualize the dynamics of gene expression by profiling absorbance or fluorescence in the supernatant of cell cultures, as well as for fluorescence labeling of individual cells. Pigment profiling can also be multiplexed with reporter proteins such as mCherry or the human model glycoprotein SEAP (secreted alkaline phosphatase). Furthermore, absorbance measurement with a smartphone camera using standard application software enables inexpensive, low-tech reporter quantification.

Reusable and Recyclable Graphene Masks with Outstanding Superhydrophobic and Photothermal Performances

The 2019 coronavirus outbreak (COVID-19) is affecting over 210 countries and territories, and it is spreading mainly by respiratory droplets. The use of disposable surgical masks is common for patients, doctors, and even the general public in highly risky areas. However, the current surgical masks cannot self-sterilize in order to reuse or be recycled for other applications. The resulting high economic and environmental costs are further damaging societies worldwide. Herein, we reported a unique method for functionalizing commercially available surgical masks with outstanding self-cleaning and photothermal properties. A dual-mode laser-induced forward transfer method was developed for depositing few-layer graphene onto low-melting temperature nonwoven masks. Superhydrophobic states were observed on the treated masks' surfaces, which can cause the incoming aqueous droplets to bounce off. Under sunlight illumination, the surface temperature of the functional mask can quickly increase to over 80 °C, making the masks reusable after sunlight sterilization. In addition, this graphene-coated mask can be recycled directly for use in solar-driven desalination with outstanding salt-rejection performance for long-term use. These roll-to-roll production-line-compatible masks can provide us with better protection against this severe virus. The environment can also benefit from the direct recycling of these masks, which can be used for desalinating seawater.