Low Optical Density Research Articles

Comparison Between Simple Batch and Fed-Batch Bioreactor Cultivation of Recombinant BCG

Background/Objectives: Tuberculosis continues to be a significant global health concern, causing 1.3 million deaths in 2022, particularly affecting children under 5 years old. The Bacillus Calmette-Guérin (BCG) vaccine, developed in 1921, remains the primary defense against tuberculosis but requires modernized production methods. The recombinant BCG-pertussis strain shows potential in providing dual protection against tuberculosis and whooping cough, especially for vulnerable newborns, and enhanced efficacy against bladder cancer. Implementing submerged cultivation techniques for rBCG-pertussis production can offer increased productivity and standardization. Methods: This study explores a fed-batch cultivation strategy with pH-stat control to feed L-glutamic acid through the acid pump into 1 L bioreactor. Three pH values were evaluated for fed-batch and a simple batch without pH control was done for comparison. The viable cell concentration was compared before and after freeze-drying samples harvested during the cultures. Results: L-glutamic acid was identified as the preferred substrate for rBCG-pertussis. While the fed-batch strategy did not enhance the maximum specific growth rate compared to simple batch cultivation, it did improve the specific growth rate after day 4 in the pH 7.4-controlled fed-batch cultures, thereby reducing the cultivation time. Fed-batch cultures controlled at three pH levels exhibited lower optical density than the simple batch, although the viable cell counts were similar. Notably, samples harvested after day 8 from the simple batch cultures showed a reduction in CFU/mL after freeze-drying, whereas all fed-batch samples exhibited high recovery of viable cell counts post lyophilization. Conclusions: The additional glutamate supplied to the fed-batch cultures may have protected the cells during the lyophilization process.

Exploring potential of tobramycin complexes for combating biofilms: In silico and In vitro studies

Nosocomial infections linked to medical implants, wound infections, and cystic fibrosis infections are mostly caused by biofilms linked to Pseudomonas aeruginosa. The development of biofilms on medical equipment continues to a growing health and financial burden with increased the risk of infections and patient morbidity associated with indwelling medical devices. Pseudomonas aeruginosa exhibited high antibiotic resistance, posing challenges for effective treatment of infections associated with medical implants. Therefore, our objective was to adopt a combinatorial approach for formulating antibiotic complexes for maximum eradication of biofilms associated with medical implants.In this study, we optimized the ratio of Tobramycin (TOB) complexes with complexing agents such as sodium bicarbonate (BC), β-cyclodextrin (β-CD), and ethylenediaminetetraacetic acid (EDTA). Further stability and flexibility of the complexes were examined through molecular docking and dynamics. Subculturing and gram staining were performed for the isolation and identification of Pseudomonas aeruginosa. The antibacterial activity was tested using the broth dilution method and well diffusion method to calculate the MIC (minimum inhibitory concentration) against Pseudomonas aeruginosa planktonic cells and biofilms, respectively. The MIC tests indicated that optimised complexes required a concentration of 8 μg/ml to eradicate both planktonic cells as well as biofilms. However, the TOB-BC-(β-CD)-EDTA complex showed lower optical density (OD) compared to other complexes exhibiting better biofilm inhibition. Subsequently a gel formulation using this optimised (TOB-BC-(β-CD)-EDTA) complex that could be applied to medical equipment or potentially converted into a film using different polymer concentrations was developed. The TOB-BC-(β-CD)-EDTA gel formulation was characterized for pH, viscosity, spread-ability, % yield, moisture content, drug content, in-vitro drug diffusion, and antibacterial efficacy assay. Among all batches, F2 demonstrated the highest % drug diffusion after 24 hours and fit well to the Korsmeyer-Peppas kinetic model. The viscosity of the F2 batch remained within acceptable limits and was stable at 40 ± 0.5 ºC and 75.0 ± 5% RH. The gel efficiently delivered antimicrobial drugs to bacteria within biofilms. In conclusion, tobramycin complex gel showed promising potential for addressing infections related to biofilms on medical implants.

Enhancing optical properties of Ba-Ni ferrite through nonmagnetic ion doping for sustainable green technologies and renewable energy applications

Barium ferrite powder was produced using a standard ceramic procedure, and its structure and optical properties were investigated. X-ray diffraction analysis (XRD) showed that the powder had a w-type hexagonal structure. The crystallite size was at approximately 35–36 nm, with bulk density and lattice constants increasing as zinc concentration rose. Conversely, X-ray density and porosity decreased with the increasing zinc concentration. This material has useful optical properties, as well as the standard ferrimagnetic properties of barium ferrite, which make it suitable for use in recording media. Ferrimagnetic behavior, which is useful for recording media, occurs because the powder's crystallites have their unit cell axes aligned. Up to the near-infrared part of the spectrum, the powder was found to have a very low absorption coefficient. Both of these properties—an arrangement that gives rise to ferrimagnetism and a corresponding low optical density—make barium ferrite very attractive for high-density recording and microwave applications. Fourier transform infrared spectra of the samples were recorded in the wavenumber range of 400–4000 cm−1 and supported the X-ray diffraction findings by confirming the idea of the formation of W-type hexagonal ferrite by the presence of two prominent peaks at 454 and 591 cm−1 in the FTIR spectra. Zinc addition was also found to enhance the optical properties of the material. The UV–VIS analysis confirms that the band gap energy of Ba-Ni ferrite was indeed reduced by zinc doping. Values decrease from 3.34 eV to 3.20 eV for direct transitions and from 2.96 eV to 2.79 eV for indirect transitions, using Tauc equation. That means that zinc doping enhances the optical properties of Ba ferrite without affecting the hexagonal structure of Ba-Ni ferrite. Moreover, key parameters of optical performance such as the dielectric constant, the extinction coefficient, the penetration depth, and the refractive index show a dramatic increase with a rise in zinc concentration. These attributes make zinc-doped Ba-Ni ferrite a promising optoelectronic material. The material also showed high absorbance in the wavelengths ranging from 334 to 338 nm, which makes it good for the solar cell applications. Overall, zinc-doped Ba-Ni ferrite is a good candidate for sustainable and renewable energy applications. Our study of the optical properties of barium ferrite up to the near-infrared part of the spectrum demonstrated that the powdered material has a very low absorption coefficient. Indeed, the combination of ferrimagnetism and low optical density makes barium ferrite particularly appealing for use in high-density recording and microwave technology applications.

Comparative evaluation of surface roughness and bacterial adhesion on two bioactive cements: an in-vitro study

BackgroundDental restorative materials are recognized as artificial niches that facilitate the adherence and accumulation of oral microorganisms. To mitigate oral diseases and extend the lifespan of restorations, it is advantageous to use dental materials that exhibit low susceptibility to bacterial adhesion.ObjectiveTo evaluate and compare bacterial adhesion on two bioactive restorative materials, a glass hybrid restorative, and an alkasite with a nanohybrid resin composite as a positive control. The secondary objectives were to compare the surface roughness (SR) of the materials and determine the correlation between the bacterial adhesion and the SR.Materials and methodsThe samples consisted of 33 polished discs of each material: Group A: Tetric® N-Ceram (nanohybrid resin composite), Group B: Equia Forte™ HT Fil (glass hybrid restorative) and Group C: Cention N® (alkasite). Streptococcus mutans cultures were inoculated and after 24-hours of incubation, bacterial adhesion was measured by measuring optical density (OD) and number of colony forming units (CFUs). After 96-hours incubation, the bacterial cell count was determined using scanning electron microscopy (SEM). SR was assessed using surface profilometer.ResultsAlkasite had significantly lower OD and CFUs (p < 0.001 and p = 0.015 respectively). According to the SEM analysis, the glass hybrid restorative had lower mean bacterial cell count with no significant difference between the groups. The nanohybrid composite had the smoothest surface that was significantly lower than the alkasite and glass hybrid restorative (p = 0.002). None of the groups demonstrated a correlation between bacterial adhesion and SR.ConclusionAlkasite impedes bacterial adhesion better than the glass hybrid restorative and nanohybrid composite, while smoother surfaces are achieved with the nanohybrid composite.

Improved Process Stability and Light Detection in Phototransistors via Inverted MoS2/a‐IGZO Heterojunction Integration

The integration of molybdenum disulfide (MoS2) with other semiconductors to form heterojunction phototransistors demonstrates potential for optoelectronic applications due to their strong interaction with light and tunable bandgaps. Conventionally, bottom‐gate phototransistors based on MoS2 and amorphous indium–gallium–zinc oxide (a‐IGZO) are fabricated by deposition of the a‐IGZO film on the gate dielectric, followed by deposition of the MoS2 film, resulting in a MoS2/a‐IGZO heterojunction. In this study, an inverted MoS2/a‐IGZO (or denoted as a‐IGZO/MoS2) heterojunction integration for bottom‐gate phototransistors, where the MoS2 film is deposited on the gate dielectric first, followed by the deposition of the a‐IGZO film, is presented. This configuration is designed to enhance the processability and electrical properties of the phototransistor. Under visible light exposure with a low optical power density of 5.3 μW cm−2, the a‐IGZO/MoS2 heterojunction phototransistor demonstrates significantly improved photoresponsivity (1.6, 2.8, and 17 A W−1 at 635, 520, and 405 nm wavelengths, respectively) compared to the MoS2 single‐channel phototransistor. Time‐dependent photoresponse measurements reveal that the a‐IGZO/MoS2 heterojunction phototransistor responds more quickly to light changes and generates a tenfold‐greater photocurrent than that of the MoS2 single‐channel phototransistor.

Cytotoxic Effect of Stenotrophomonas maltophilia Isolated from Prostate and Bladder Cancer Patients in Iraq.

This study investigated the cytotoxic effects of Stenotrophomonas maltophilia on normal human cells. Seven isolates of S. maltophilia were obtained from 120 urine samples collected from prostate and bladder cancer patients, with diagnoses confirmed via Vitek. The cytotoxicity of these bacterial isolates was assessed on normal human fibrocyte cells (NHF) using various concentrations of bacterial filtrate (3.125, 6.25, 12.5, 25, 50, and 100 μg/ml). The bacterial filtrate exhibited significant toxicity to NHF cells, with the highest cell death rate of 68% and the lowest optical density (OD) of 0.25 at a concentration of 100 μg/ml. The IC50 value, indicating the concentration at which 50% inhibition of cell viability occurred, was determined to be 49.35 μg/ml. Further research is necessary to explore the potential role of these bacterial isolates in promoting cancer through inflammation. The clinical isolates of S. maltophilia demonstrated substantial cytotoxic activity against normal human fibrocyte cells, leading to a notable reduction in both cell number and optical density, with the highest percentage of cell death observed. These findings suggest the need for further investigation into the specific toxins or enzymes involved, which could pave the way for future studies.

Design optimization of a modified Uni-Traveling- carrier photodiode for high optical power operation

We systematically investigated the design optimization of an InGaAs/InP modified Uni-Traveling-Carrier Photodiode (MUTC-PD) under high optical power input conditions. Based on internally fabricated experimental devices for a baseline design, we first achieved an excellent match between our experimental and simulation results under low optical power density of 1.4 mW/μm2, demonstrating the accuracy of our simulation model. Based on this model we showed that as optical power injection increases, the intrinsic bandwidth of the MUTC-PD degradation is the primary limitation on its high-speed response. We quantitatively analyzed the fundamental carrier transport physics and key design parameters affecting intrinsic bandwidth degradation under these conditions. In particular cliff layer doping concentration was found to be a very sensitive parameter affecting the MUTC-PD Optical Electrical (OE) intrinsic bandwidth. Based on detailed simulated results, we realized an optimized device design that is capable of achieving a 3 dB bandwidth of approximately 230 GHz at 10 mW/μm2 input optical power density for the first time.

Low Macular Pigment Optical Density Is Associated with Manifest Primary Open-Angle Glaucoma in Older Women

BackgroundLower density of carotenoids lutein and zeaxanthin (L/Z) in the macula (i.e., macular pigment) has been linked to greater risk for age-related eye disease. ObjectivesWe evaluated whether macular pigment optical density (MPOD) was associated with manifest primary open-angle glaucoma (POAG) among older women in the Carotenoids in Age-Related Eye Disease Study 2 (CAREDS2). MethodsMPOD was measured with customized heterochromatic flicker photometry in women who attended CAREDS2 (2016–2019) and CAREDS1 (2001–2004) study visits. Manifest POAG at CAREDS2 was assessed using visual fields, disc photos, optical coherence tomography, and medical records. Age-adjusted linear and logistic regression models were used to investigate the cross-sectional association between POAG and MPOD at CAREDS2, and MPOD measured 15 years earlier at CAREDS1. ResultsAmong 426 CAREDS2 participants (mean age: 80 y; range: 69–98 y), 26 eyes with manifest POAG from 26 participants were identified. Glaucomatous eyes had 25% lower MPOD compared to nonglaucomatous eyes [mean (SE): 0.40 (0.05) compared with 0.53 (0.01)] optical density units (ODU), respectively (P = 0.01). Compared with MPOD quartile 1, odds for POAG were lower for women in quartiles 2–4 (P-trend = 0.01). After excluding eyes with age-related macular degeneration, associations were similar but not statistically significant (P-trend = 0.16). Results were similar for MPOD measured at CAREDS1. ConclusionsOur results add to growing evidence that low MPOD may be a novel glaucoma risk factor and support further studies to assess the utility of dietary interventions for glaucoma prevention.

Investigation of factors that may affect the foveal avascular zone: An optical coherence tomography angiography study

SIGNIFICANCE An understanding of factors that affect the foveal avascular zone (FAZ) in healthy eyes may aid in the early identification of patients at risk of retinal pathology, thereby allowing better management and preventive measures to be implemented. PURPOSE The size and shape of the FAZ can change due to retinal diseases associated with oxidative stress, including diabetic retinopathy, glaucoma, and macular degeneration. This study aimed to assess the relationship, if any, between factors that may affect the superficial FAZ (i.e., vessel density, vessel perfusion, overweight/obesity) and possible links with macular pigment optical density in young, healthy participants. METHODS One hundred thirty-nine participants aged 18 to 35 years were recruited to this cross-sectional study. The superficial FAZ area, foveal vascularity, and central macular thickness (CMT) were assessed using the Cirrus 5000. Health parameters, body mass index, trunk fat %, and macular pigment were analyzed to determine possible associations with the superficial FAZ. RESULTS Mean FAZ area was 0.23 ± 0.08 mm2. Females had a significantly larger mean FAZ area than males (p=0.002). The FAZ area was positively correlated with body mass index (Pearson's r = 0.189, p=0.026). Significant correlates of the FAZ area in the multivariate model included vessel perfusion (central), CMT, and trunk fat %, collectively explaining 65.1% of the overall variability. CONCLUSIONS Study findings suggest that reduced vessel perfusion, thinner CMT, and higher trunk fat % are plausible predictors of a larger FAZ area in healthy Caucasian adults. Low macular pigment optical density was, however, not associated with increased FAZ size in young healthy eyes. Noninvasive optical coherence tomography angiography testing, in association with these predictors, may aid in the early detection and monitoring of retinal diseases associated with oxidative stress.

Study of PG-Added Fountain Solution for Printing Offset Technique

Although the printing technology, especially offset printing, has changed and grown quickly based on advanced invention and production capacity. However, the old offset machine printing such as one or two colour offset machines are still used massively in development countries. It is unpredictable when the old printing technology eliminated completely from the community, since it is affected by the economic level and extraordinary need of the public such as public election. The old machine which has been produced for more than 10 years usually has an issue related to the ink-water balance (iwb). The use of propylene glycol (PG) as single wetting agent improved iwb based on our previous study. Therefore, the effect of PG with fountain solution to the print quality is studied here. A series of fountain solution (FS) with additional content of 0 ppm, 13 ppm, 20 ppm, 40 ppm of PG was used to print an image on the art paper surface using sakurai offset machine. The optical parameters such as optical density (OD) and L*a*b were used to observe the effect of PG content in FS to the quality of printing. The OD on 0 ppm (reference), 13 ppm, 20 ppm and, 40 ppm of PG were 1.76 (reference), 1.83, 1.76, and 1.74, respectively. The optical density was identified as the maximum value at 1.83 on raster 100% of black colour for PG 13 ppm. At 13 ppm PG-added FS, the ΔE values of black (K) and Magenta (M) were 5.2 and 9.8, respectively, while ΔE values of cyan (C) and yellow (Y) were 1.7 and 1.8, respectively. It meant at PG 13 ppm, the K and M were stronger than the reference, while C and Y were equal. The same and lower OD compared to the reference showed unimproved color.&#x0D; Keywords: offset printing, fountain solution, propylene glycol

FEATURES OF COL1A1 EXPRESSION IN BREAST CANCER TISSUE OF YOUNG PATIENTS.

In the last decades, the incidence of breast cancer (BCa) in young women has been increasing steadily. The quantitative indicators of expression of collagen, which play important role in stromal microenvironment, and their association with the age and survival rates of BCa patients have not been yet definitively clarified. To investigate the relationship between the COL1A1 gene expression at the mRNA and protein levels in BCa tissue and the clinicopatological features and survival rates of BCa patients of different age groups. The study was conducted on the clinical material of 50 patients with stage I-III BCa. COL1A1 gene expression at the mRNA and protein levels in BCa tissue were studied using the real-time PCR and immunohistochemical methods, as well as the bioinformatic analysis (UALCAN and Kaplan - Meier Plotter databases). The bioinformatic analysis showed that BCa tissue is characterized by 6.0 times (p < 0.05) higher level of COL1A1 mRNA compared to normal breast tissue. The correlation of COL1A1 expression at the mRNA and protein levels with the molecular subtype of neoplasms was demonstrated. According to Kaplan - Meier Plotter database, a low level of expression of COL1A1 protein level in BCa tissue is associated with lower rates of relapse-free survival of patients. The ex vivo study of the clinical material revealed a decrease in COL1A1 protein expression in tumor tissue of young patients with BCa of T3 category (p < 0.0374), low differentiation grade (p < 0.0163) and basal molecular subtype (p < 0.0001). A correlation between the expression of COL1A1 at the mRNA and protein levels and the expression status of estrogen receptors (p < 0.0001) and progesterone receptors (p < 0.0040) was established. The relapse-free 3-year survival rate of young BCa patients is significantly lower in the presence of a low COL1A1 optical density index in the tumor tissue. The identified relationship between COL1A1 expression and such indicators of BCa malignancy as tumor size, differentiation grade, molecular subtype, receptor status, and the recurrencefree survival of patients indicates the prospects of its use to predict the aggressiveness of the BCa course in young patients.

Amylase production from marine sponge Hymeniacidon perlevis; potentials sustainability benefits.

The marine sponge Hymeniacidon perlevis is a globally distributed and invasive species with extensive filter-feeding characteristics. The symbiotic relationship fostered between the sea sponge and the inhabiting microorganism is key in the production of metabolic enzymes which is the focus of this study. Sponge bacterial symbionts were grown on starch agar for 48hrs. Colourimetric analyses of amylase were conducted at 540nm using a spectrophotometric plate reader. Using an X-Bridge column (3.5μM, 4.6x150mm), 80/20 acetonitrile/water in 0.1% ammonium were the conditions used for the liquid chromatography-mass spectrometry (LC-MS) analyses. Seven reducing sugars were used to optimise LC-MS to determine the presence of the crude enzyme formed. Not all the bacterial symbionts isolated from H perlevis produced alpha and beta amylases to break down starch. From the statistical mean of crude enzyme concentrations from the hydrolysis of starch by amylase, isolate seven had the highest optical density (OD) at 0.43475 while isolate twelve had the lowest OD at 0.141417. From the LC-MS analysis, out of the seven sugars, Glucose and maltose constituted > 65% of the reducing sugars formed from the hydrolysis of starch by the amylases. Isolates 3,6 and 7 produced 6.906 mg/l, 12.309 mg/l, and 5.909 mg/l of glucose, while isolates 3,4,5,6 and 7 produced 203.391 mg/l, 176.238 mg/l, 139.938 mg/l, 39.030 mg/l, and 18.809 mg/l of maltose, respectively. Isolate two had the highest amount of maltose at a concentration of 267.237 mg/l while isolate four had the highest amount of glucose concentration of 53.084 mg/l. Enzymes from marine sponge bacteria offer greater potential for a green and sustainable production process. Amylase extraction from bacterial symbionts in H perlevis is sustainable and should be supported. They can serve as reliable sources of revenue for enzyme industries, and applications in food industries and biotechnological processes.

Corrigendum to “Efficient adsorption-photocatalytic performance of La2S3/MgO-modified biochar in the removal of tetracycline hydrochloride at a low optical density” [Mater. Sci. Semicond. Process. 165 (2023) 107690

Corrigendum to “Efficient adsorption-photocatalytic performance of La2S3/MgO-modified biochar in the removal of tetracycline hydrochloride at a low optical density” [Mater. Sci. Semicond. Process. 165 (2023) 107690

Efficient adsorption-photocatalytic performance of La2S3/MgO-modified biochar in the removal of tetracycline hydrochloride at a low optical density

Efficient adsorption-photocatalytic performance of La2S3/MgO-modified biochar in the removal of tetracycline hydrochloride at a low optical density

Green Synthesis of Titanium Oxide Nanoparticles With Rosemary and Ginger and Their Bactericidal Action Against Staphylococcus aureus.

Titanium oxide (TiO2) nanoparticles (NPs) have significantly proved to be highly useful in restorative materials, dental adhesives, sealants, cements, and other dental applications to prevent microbial colonization and reduce the risk of infections. The present study was aimed at developing a dental material with antibacterial properties by combining titanium oxide NPs using ginger and rosemary extracts. The formulation was prepared using rosemary and ginger, mediated by TiO2 NPs. The preparation was then introduced into the wells of a microplate consisting of cultured Staphylococcus aureus and was kept for incubation for four hours. To record the minimum inhibitory concentration, the test solution was added into Kimble tubes consisting of Muller-Hinton broth. The results obtained were statistically analyzed using one-way ANOVA. Increasing concentration led to decreased optical density, indicating bactericidal effects. Significantly lower optical density values were observed in decreasing order among the test samples (25, 50, and 100 μL) compared to control and antibiotic groups against Streptococcus, highlighting the potent antibacterial and antibiofilm properties of the greenly generated combination of titanium oxide NPs with herbs. This was also confirmed by moderate minimum inhibitory concentration at 100 μL. The present study suggests that there is a bactericidal process at play, leading to a reduction in the overall bacterial count. It can be concluded that the ginger and rosemary-mediated titanium oxide NPs serve as potential antibacterial agents against S. aureus. This study can be used as a preliminary study, and further studies can be conducted to use this formulation in the field of medicine.

Investigation and evaluation of a 3D-printed optical modified cultivation vessel for improved scattered light measurement of biotechnologically relevant organisms.

In the field of bioprocess development miniaturization, parallelization and flexibility play a key role reducing costs and time. To precisely meet these requirements, additive manufacturing (3D-printing) is an ideal technology. 3D-printing enables rapid prototyping and cost-effective fabrication of individually designed devices with complex geometries on demand. For successful bioprocess development, monitoring of process-relevant parameters, such as pH, dissolved oxygen (DO), and biomass, is crucial. Online monitoring is preferred as offline sampling is time-consuming and leads to loss of information. In this study, 3D-printed cultivation vessels with optical prisms are evaluated for the use in upstream processes of different industrially relevant microorganisms and cell lines. It was shown, that the 3D-printed optically modified well (OMW) is of benefit for a wide range of biotechnologically relevant microorganisms and even for mammalian suspension cells. Evaluation tests with Escherichia coli, Bacillus subtilis, Saccharomyces cerevisiae, and Chinese hamster ovary (CHO) cells were performed, providing highly reproducible results. Growth behavior of OMW cultures was comparable to behavior of shake flask (SF) cultivations and the signal to noise ratio in online biomass measurement was shown to be reduced up to 95.8% by using the OMW. Especially the cultivation phases with low turbidity respective optical densities below 1.0rel.AU could be monitored accurately for the first time. Furthermore, it was demonstrated that the 3D-printed optics are transferable to different well geometries and sizes, enabling efficient biomass monitoring for individual requirements with tailor-made 3D-printed cultivation vessels in small scale.

New ultrafast low-cost polyurethane based plastic scintillator

The study of plastic scintillators with polyurethane (PU) matrix based on cycloaliphatic isocyanate 4,4′-methylenebis (cyclohexyl isocyanate) (H12MDI) and 2,5-diphenyloxazole (PPO) as a luminescence activator is presented. A number of samples with different PPO content amounting up to 20 wt% were synthesized and their optical and luminescence characteristics were investigated. Pure H12MDI – PU based polymer exhibits low optical density in the spectral region 350–500 nm characteristic of the PPO emission band. The PU sample loaded with 5 wt% PPO demonstrated a light yield of 1088 photons/MeV and ultrafast rise and decay time of few picoseconds and few nanoseconds, respectively. The estimated coincidence time resolution (CTR) value for a PU sample is 1.4 times smaller than that known for a commercial scintillator BC-422 available for ultrafast timing applications.

The influence of negative pressure wound therapy on bacterial and fungal growth

BackgroundThe use of negative pressure wound therapy (NPWT) in superinfected wounds is controversial. The mechanism of action is unclear, but recent studies have shown lower atmospheric oxygen levels within the dressing. Therefore, different oxygen-favoring bacteria and fungi might benefit or face impaired thriving conditions. The aim of this in vitro study is to investigate the influence of NPWT on bacterial and fungal growth. MethodsSalmonella enterica subsp. enterica serovar Typhimurium, Pseudomonas aeruginosa and Candida albicans strains were cultured on concentrated agars and attached to a standard NPWT-device. After 48 hours, colonies were separately harvested from the agar and foam. Optical density (OD) was obtained in order to estimate bacterial loads. ResultsFor all tested microorganisms, no overall significant differences were found compared to controls. Subanalysis showed lower OD levels from the agar beneath the foam in the NPWT-group. ConclusionNPWT removed bacteria and fungi from the wound surface but accumulation is found within the foam. The use of NPWT showed no influence on bacterial or fungal growth selection. With superinfected wounds, the use of NPWT should thoroughly be evaluated as toxins and virulence factors may not fully be evacuated.

Image reconstruction for low cost spatial light interference microscopy with fixed and arbitrary phase modulation.

During the past decade, spatial light interference microscopy (SLIM) has undergone rapid development, evidenced by its broadening applications in biology and medicine. However, the need for an expensive spatial light modulator (SLM) may limit its adoption, and the requirement for multiple images per plane limits its speed in volumetric imaging. Here we propose to address these issues by replacing the SLM with a mask fabricated from a low cost optical density (OD) filter, and recover high contrast images computationally rather than through phase-shifting. This is done using a specially constructed Wiener filter to recover the object scattering potential. A crucial part of the Wiener filter is estimating the arbitrary phase introduced by the OD filter. Our results demonstrate that not only were we able to estimate the OD filter's phase modulation in situ, but also the contrast of the reconstructed images is greatly improved. Comparisons with other related methods are also performed, with the conclusion that the combination of an inexpensive OD mask and modified Wiener filtering leads to results that are closest to the traditional SLIM setup. Thus, we have demonstrated the feasibility of a low cost, high speed SLIM system utilizing computational phase reconstruction, paving the way for wider adoption of high resolution phase microscopy.

Fabrication of Rigid Isocyanate-Based Polyimide Foam Achieved Excellent Use Safety via Synergy between Expandable Graphite and Phosphorus-Containing Polyol

For the advantages of low cost, excellent thermal insulation, and sound absorption properties, the rigid isocyanate-based polyimide foam (RPIF) presents great application prospects as a building insulation material. However, its inflammability and the accompanying toxic fumes create huge safety hazard. In this paper, reactive phosphate-containing polyol (PPCP) is synthesized and employed with expandable graphite (EG) to obtain RPIF with excellent use safety. EG can be considered as an ideal partner for PPCP to weaken the drawbacks in toxic fume release. Limiting oxygen index (LOI), cone calorimeter test (CCT), and toxic gas results show that the combination of PPCP and EG can synergistically enhance flame retardancy and the use safety of RPIF owing to the unique structure of a dense char layer possessing a flame barrier and toxic gas adsorption effects. When EG and PPCP are simultaneously applied to the RPIF system, the higher EG dosage will bring higher positive synergistic effects in the use safety of RPIF. The most preferred ratio of EG and PPCP is 2:1 (RPIF-10-5) in this study; RPIF-10-5 shows the highest LOI, low CCT results and specific optical density of smoke, and low HCN concentration. This design and the findings are of great significance to improving the application of RPIF.