Search

Background: The present study attempted to determine the antibiotic susceptibility of bacteria isolated from endotracheal tube culture on patients admitted to the intensive care units (ICUs) of Shahid Mohammadi hospital in Bandar Abbas. Materials and Methods: This cross-sectional study was conducted on 114 patients hospitalized in the pulmonary ICU of Shahid Mohammadi hospital in Bandar Abbas from March 2018 to March 2019. The samples of the patients’ endotracheal tube secretions were collected for the culture purpose on the first and fifth days of hospitalization in the ICU where the disk diffusion method was used to determine antibiotic susceptibility. Results: The most common isolated microorganisms from the first day of culture were 26 Acinetobacter spp. isolates (22.8%), 10 Candida isolates (8.8%), and 9 Pseudomonas aeruginosa isolates (7.9%). The most common microorganisms which were isolated on the fifth day comprised Acinetobacter spp. with 57 isolates (51.8%), Candida with 6 isolates (5.5%), and P. aeruginosa with 6 isolates (5.5%). The highest resistant bacteria isolated from Acinetobacter spp. samples on the first-day were amikacin (92.3%) and meropenem (84.6%). The highest resistance of P. aeruginosa was against meropenem (77.8%), while the highest resistance of Acinetobacter spp. isolates was found to be amikacin (94.7%) and meropenem (86%) from the fifth-day samples. Further, P. aeruginosa isolates had the highest resistance in meropenem (83.3%), co-trimoxazole, and cefepime (66.7% for each of them). Conclusion: Ventilator-associated pneumonia (VAP) is considered a warning condition due to multidrug-resistant bacteria. According to the present study, the most common VAP-causing bacteria are gram-negative, especially Acinetobacter, with high antibiotic resistance.

Background: According to the evidence, coronavirus disease 2019 (COVID-19) is associated with significant mortality among hospitalized patients. Corticosteroid drugs have had different effects on disease-associated fatality. This study aimed to evaluate the corticosteroid-associated mortality rate and its related risk factors in the southern Iranian population infected by COVID-19. Methods: A retrospective study was conducted on the adult population aged≥20 years admitted to Shahid Mohammadi hospital in Bandar Abbas, Iran between February 2020 and October 2020. All subjects were confirmed for COVID-19 by reverse transcriptase-polymerase chain reaction (RT-PCR). Results: Among 1610 included cases, 150 (9.3%) died. Also, 58.5% and 58.7% of the total hospitalized and mortality cases were male, respectively. The mortality rate in subjects older than 60 years was 2.5 times higher than patients aged 40 years, which was statistically significant (P60) had nearly ten times higher chance of fatality than patients aged less than 40 years (adjusted odds ratio [aOR]: 9.79, 95% CI: 4.41-21.74). Using corticosteroids independently increased the chance of mortality by 50% (aOR: 1.53, 95% CI: 1.06-2.22). Low oxygen saturation (

Background: Today, various drugs have been investigated as the primary or complementary treatment for coronavirus disease 2019 (COVID-19). N-acetylcysteine (NAC) has been used as a mucolytic in pulmonary diseases. This drug apparently contributes to the retrieval of the intracellular antioxidant system. Objectives: This study aimed to determine the efficacy of NAC in severe COVID-19 patients admitted to the intensive care unit (ICU). Methods: This single-blinded randomized controlled phase III clinical trial included 40 patients with confirmed COVID-19 (based on polymerase chain reaction) admitted to the Shahid Mohammadi Hospital’s ICU, Bandar Abbas, Iran, in 2020. All cases had severe COVID-19. They were allocated randomly to two equal groups. Patients in the control group received standard drug therapy based on the treatment protocol of the national COVID-19 committee, while those in the NAC group received a single dose of intravenous NAC (300 mg/kg) upon admission to the ICU in addition to standard drug treatment. Clinical status and laboratory tests were done on admission to the ICU and then 14 days later or at discharge without knowing the patient grouping. Results: The two groups were comparable regarding age, gender, and other baseline laboratory and clinical parameters. At the final evaluation, respiratory rate (21.25 ± 4.67 vs. 27.37 ± 6.99 /min) and D-dimer (186.37 ± 410.23 vs. 1339.04 ± 2183.87 ng/mL) were significantly lower in the NAC group (P = 0.004 and P = 0.030, respectively). Also, a lower percentage of patients in the NAC group had lactate dehydrogenase (LDH) ≤ 245 U/L (0% vs. 25%, P = 0.047). Although the length of ward and ICU stay was shorter in the NAC group than in controls, the difference was statistically insignificant (P = 0.598 and P = 0.629, respectively). Mortality, on the other hand, was 75% in the control group and 50% in the NAC group, with no statistically significant difference (P = 0.102). Concerning the change in the study parameters, only the decrease in diastolic blood pressure (DBP) was significantly higher with NAC (P = 0.042). The intubation and mechanical ventilation rates were higher, while oxygen with mask and nasal oxygen rates were lower with NAC, but the difference was statistically insignificant. Conclusions: Based on the current research, NAC is related to a significant decrease in RR, D-dimer, and DBP in severe COVID-19. Also, LDH was significantly lower in the NAC group than in the controls. More research with larger sample sizes is needed to validate the current study results.

BackgroundMetabolic syndrome (MetS) is defined as the presence of several metabolic risk factors. The traditional MetS criteria have been considered insufficient for evaluating individuals at risk. MetS has always been categorized using binary criteria, which deny that the risk associated with MetS is likely to exist as a continuum. Also, MetS may present differently depending on age, sex, race, or ethnicity. We aimed to derive age-sex-specific equations for MetS severity scores within a southern Iranian population.MethodsThis study used first-phase data from the Bandare-Kong Non-Communicable Diseases (BKNCD) Cohort Study as part of the Prospective Epidemiological Research Studies in IrAN (PERSIAN). After exclusion of the pregnant women, diabetic patients, and individuals taking antihypertensive, antihyperlipidemic, and antidiabetic medications, 2,735 individuals aged 35 to 70 years were selected for analysis. The diagnosis of MetS was based on the National Cholesterol Education Program (NCEP) criteria for the Iranian population. Confirmatory factor analysis (CFA) was performed to formulate MetS severity scores. The receiver operating characteristic (ROC) analysis was performed to validate MetS severity score equations for age-sex-specific categories.ResultsTriglyceride had the highest factor loading range in all age-sex categories for determining the MetS severity score. Conversely, systolic blood pressure and fasting plasma glucose (FPG) exhibited the lowest factor loadings across all age-sex groups. In both sexes, when age was considered, systolic blood pressure and FPG factor loadings were less significant among subjects aged ≥45 and 35–44 years, respectively.ConclusionMetS severity scores might be more applicable than the current criteria of MetS. Prospective population-based studies should be conducted to assess the accuracy and validity of the MetS severity score for predicting cardiometabolic diseases.

The novel coronavirus infection 2019 (COVID-19) is a pandemic viral disease officially named by World Health Organization (WHO) on March 11, 2020. It is mainly a respiratory disease but can involve other organs. Extrapulmonary presentations are broad and not well recognized. COVID-19 may trigger diabetic ketoacidosis (DKA) in a patient with adequately controlled diabetes. Pregnancy is an incomplete immune suppression status, making women more susceptible to infections, and the disease-related morbidity is higher during pregnancy. Herein, we present the case of a 23-year-old diabetic pregnant woman at 28 weeks gestation with acute pancreatitis, DKA, hypertriglyceridemia, with confirmed COVID-19 infection using polymerase change reaction (PCR). She underwent antiviral therapy, adequate intravenous hydration, insulin infusion, and plasmapheresis in the intensive care unit (ICU). Her condition ultimately improved. COVID-19 with simultaneous pregnancy and diabetes mellitus increases the risk of metabolic disorders. Therefore, rapid diagnosis and adequate management would be considered.

Omnidirectional broadband terahertz (THz) antireflection (AR) with an actively configurable coating promises the achievement of next-generation efficient and versatile THz components with high performance. We demonstrate a near-infrared (NIR) light-tunable and omnidirectional broadband THz AR coating based on an impedance matching method and composed of a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/graphene composite film. The omnidirectional broadband properties of the active AR coating can be efficiently achieved by tunable NIR optical excitation of less than 0.27 W·cm

Lead toxicity is hindering the applications of conventional lead halide perovskites (PVKs), and antimony (Sb) is a promising nontoxic Pb alternative, showing huge potential in optoelectronic devices. Herein, pure and Mn-doped Cs3Sb2Cl9 crystals are synthesized in a facile route and studied both experimentally and theoretically. All the pure and Mn-doped Cs3Sb2Cl9 crystals show good crystallinity and similar crystal structures, exhibiting visible photoluminescence (PL) characteristics with emission peaks at 422 and 613 nm, respectively. Combined density functional theory (DFT) calculations and experimental analyses reveal that the structure of the host PVK compound Cs3Sb2Cl9 is not influenced by the formation of [MnCl6]4- octahedra and that Mn 3d orbitals generate impurity states in the forbidden energy gap of Cs3Sb2Cl9. Therefore, energy transfer from Cs3Sb2Cl9 to Mn 3d states is observed, resulting in the d-d transition and bright red luminescence. Mn-doped Sb-based PVK can be utilized as a new platform for optoelectronic applications.

Chiral photonics opens new pathways to manipulate light-matter interactions and tailor the optical response of metasurfaces and -materials by nanostructuring nontrivial patterns. Chirality of matter, such as that of molecules, and light, which in the simplest case is given by the handedness of circular polarization, have attracted much attention for applications in chemistry, nanophotonics and optical information processing. The design of chiral photonic structures using two machine learning methods, the evolutionary algorithm, and neural network approach, for rapid and efficient optimization of optical properties for dielectric metasurfaces, is reported. The design recipes obtained for visible light in the range of transition-metal dichalcogenide exciton resonances show a frequency-dependent modification in the reflected light's degree of circular polarization, that is represented by the difference between left- and right-circularly polarized intensity. Our results suggest the facile fabrication and characterization of optical nanopatterned reflectors for chirality-sensitive light-matter coupling scenarios employing tungsten disulfide as possible active material with features such as valley Hall effect and optical valley coherence.

Objectives Severe acute respiratory infection (SARI) caused by the SARS-CoV-2 virus may cause lung failure and the need for mechanical ventilation. Infection with SARS-COV-2 can lead to activation of inflammatory factors, increased reactive oxygen species, and cell damage. In addition to mucolytic effects, N-Acetylcysteine has antioxidant effects that we believe can help patients recover. In this study, we evaluate the efficacy of N-Acetylcysteine in patients with severe COVID-19. Trial design This is a prospective, randomized, single-blinded, phase 3 controlled clinical trial with two arms (ratio 1:1) parallel-group design of 40 patients, using the placebo in the control group. Participants All severe COVID-19 patients with at least one of the following five conditions: (respiration rate > 30 per minute), hypoxemia (O2 ≤ saturation, arterial oxygen partial pressure ratio 50% of lung area during 24 48 h), Lactate dehydrogenase (LDH) > 245 U / l, Progressive lymphopenia, and admitted to the intensive care unit of Shahid Mohammadi Hospital in Bandar Abbas and have positive PCR test results for SARS-Cov-2 and sign the written consent of the study will be included. Patients will be excluded from the study if they have a history of hypersensitivity to N-Acetylcysteine, pregnancy, or refuse to participate in the study. Intervention and comparator After randomization, participants in the intervention group receive standard of care (SOC) according to the National Committee of COVID-19 plus N-acetylcysteine (EXI-NACE 200mg/mL, in 10mL ampules of saline for parenteral injection (EXIR pharmaceutical company)) at a dose of 300 mg/kg equivalent to 20 gr as a slow single intravenous injection on the first day of hospitalization. In the control group patients receive SOC and placebo ( Sterile water for injection as the same dose). The placebo is identical in appearance to the N-acetylcysteine injection (EXIR pharmaceutical company as well). Main outcomes The primary endpoint for this study is a composite endpoint for the length of hospitalization in the intensive care unit and the patient's clinical condition. These outcomes were measured at the baseline (before the intervention) and on the 14th day after the intervention or on the discharge day. Randomisation Eligible participants (40) will be randomized in two arms in the ratio of 1: 1 (20 per arm) using online web-based tools and by permuted block randomization method. To ensure randomization concealment, random sequence codes are assigned to patients by the treatment team at the time of admission without knowing that each code is in the intervention or comparator group. Blinding (masking) All participants will be informed about participating in the study and the possible side effects of medication and placebo. Patients participating in the study will not be aware of the assignment to the intervention or control group. The principal investigator, health care personnel, data collectors, and those evaluating the outcome are aware of patient grouping. Numbers to be randomised (sample size) A total of 40 patients participate in this study, which are randomly divided; 20 patients in the intervention group will receive SOC and N-acetylcysteine, 20 patients in the control group will receive SOC and placebo. Trial status First version of the protocol was approved by the Deputy of Research and Technology and the ethics committee of Hormozgan University of Medical Sciences on February 14, 2021, with the local code 990573, and the recruitment started on March 2, 2021 and the expected recruitment end date is April 1, 2021. Trial registration The protocol was registered before starting participant recruitment entitled: Evaluation of the efficacy of N-Acetylcysteine in severe COVID-19 patients: a randomized controlled phase III clinical trial, IRCT20200509047364N3, at Iranian Registry of clinical trials on 20 February 2021. Full protocol The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol. The study protocol has been reported in accordance with the Standard Protocol Items: Recommendations for Clinical Interventional Trials (SPIRIT) guidelines (Additional file 2).

Two-dimensional (2D) heterostructures (HS) formed by transition-metal dichalcogenide (TMDC) monolayers offer a unique platform for the study of intralayer and interlayer excitons as well as moiré-pattern-induced features. Particularly, the dipolar charge-transfer exciton comprising an electron and a hole, which are confined to separate layers of 2D semiconductors and Coulomb-bound across the heterojunction interface, has drawn considerable attention in the research community. On the one hand, it bears significance for optoelectronic devices, e.g. in terms of charge carrier extraction from photovoltaic devices. On the other hand, its spatially indirect nature and correspondingly high longevity among excitons as well as its out-of-plane dipole orientation render it attractive for excitonic Bose-Einstein condensation studies, which address collective coherence effects, and for photonic integration schemes with TMDCs. Here, we demonstrate the interlayer excitons' out-of-plane dipole orientation through angle-resolved spectroscopy of the HS photoluminescence at cryogenic temperatures, employing a tungsten-based TMDC HS. Within the measurable light cone, the directly-obtained radiation profile of this species clearly resembles that of an in-plane emitter which deviates from that of the intralayer bright excitons as well as the other excitonic HS features recently attributed to artificial superlattices formed by moiré patterns.

Background A variety of health problems, such as metabolic syndrome (MetS), have been linked to sleep disorders. While numerous epidemiological studies have shown a U-shaped relationship between sleep duration and poor health outcomes, the results were limited and inconsistent. This study was designed to evaluate the relationship between sleep duration and MetS. Methods This population-based study was conducted on the participants aged 35–70 of Bandare-Kong Non-Communicable Diseases (BKNCD) Cohort Study, a part of Prospective Epidemiological Research Studies in IrAN (PERSIAN). MetS was diagnosed according to the National Cholesterol Education Program (NCEP) criteria and the Iranian-specific cut-off for waist circumference (≥ 95 cm). Sleep information was extracted through a standard questionnaire based on self-reported information. Data were analyzed by R software using generalized additive models (GAMs). A statistically significant level was considered as P Results A total of 3695 participants were included in the analyses. The mean age was 48.05 years (SD 9.36), and 2067 (55.9%) were female. The estimated Prevalence of MetS was 35.9%, and women appeared to be more likely to have MetS than men (P Conclusion Long sleep duration was associated with increased risk of MetS and higher MetS severity score in both genders, while the short sleep duration increased the risk of Mets as well as MetS severity score just in women. The longitudinal studies would be suggested to assess the relationship between sleep quality and quantity components and MetS.

The atomically thin two-dimensional semiconductors of the material family of transition-metal dichalcogenides exhibit astonishing many-particle physics dominated by the formation of tightly bound planar-confined excitons due to strong in-plane Coulomb interaction. In addition to bright excitonic features, the presence of various dark excitonic states also has been experimentally observed very recently in this material family. In addition to that, a different type of exciton emerges when a van-der-Waals heterostructure is assembled by deterministically stacking two different monolayer TMDCs. Here, we demonstrate a WSe2/WS2 type-II heterostructure where the electrons transfer to the WS2 layer whereas the holes transfer to the WSe2 layer, thereby giving rise to interlayer excitons. The interlayer interaction depends on the coupling strength of the heterostructure which determines the luminescence spectrum. Such spectrum features contributions from individual layers as well as the heterobilayer configuration. These results and findings open new approaches for bandgap engineering using strongly hybridized bandstructures.

Valley-selective optical selection rules and a spin-valley locking in transition-metal dichalcogenide (TMDC) monolayers are at the heart of “valleytronic physics”, which exploits the valley degree ...

Background and aim: Contamination of microorganisms, including Staphylococcus Aureus, in oral saliva and oral tissues, is a common problem. Therefore, in this study, photodynamic therapy's effect on the number of oral Staphylococcus Aureus colonies. Was evaluated using two indices of Indocyanine Green and Methylene Blue with sensitizer with Chlorhexidine mouthwash. Materials and methods: In the first stage, a new culture of ATCC St.Aureus 25923 was performed. Colonies of Staphylococcus Aureus were counted. The teeth were randomly divided into four groups: the first group was Methylene Blue, and the second group was subjected to 2% Indocyanine Green. All samples from both groups were sampled before laser irradiation and colonized in the culture medium for 24 hours. The third group of teeth was immersed in 2% Chlorhexidine mouthwash and sampled. The fourth group was considered as the control group. Also, Post hoc analysis was used for comparing before and after treatment in each group. Results: This study showed that all three experimental groups reduced the number of Staphylococcus Aureus colonies. However, Indocyanine Green and Methylene Blue did not significantly decrease the number of colonies before and after treatment (p> 0.05), but Chlorhexidine caused a significant decrease in the number of Staphylococcus colony Aureus (p

Light-matter interactions with two-dimensional materials gained significant attention in recent years, leading to the reporting of weak and strong coupling regimes and effective nanolaser operation with various structures. Particularly, future applications involving monolayer materials in waveguide-coupled on-chip-integrated circuitry and valleytronic nanophotonics require controlling, directing, and optimizing photoluminescence. In this context, photoluminescence enhancement from monolayer transition-metal dichalcogenides on patterned semiconducting substrates becomes attractive. It is demonstrated in our work using focused-ion-beam-etched GaP and monolayer WS2 suspended on hexagonal boron nitride buffer sheets. We present an optical microcavity approach capable of efficient in-plane and out-of-plane confinement of light, which results in a WS2 photoluminescence enhancement by a factor of 10 compared to that of the unstructured substrate at room temperature. The key concept is the combination of interference effects in both the horizontal direction using a bull's-eye-shaped circular Bragg grating and in the vertical direction by means of a multiple-reflection model with optimized etch depth of circular air-GaP structures for maximum constructive interference effects of the applied pump and expected emission light.

INTRODUCTION: Agricultural commodities contaminated by molds and mycotoxins can be considered as public health problems in less developed countries, particularly in Iran. Hence the main purpose of this study was to identify mold fungi and molecular analysis of the most important species of aflatoxin-B1-producing Aspergillus species in some dried nuts and grains in local markets in Tehran. MATERIALS AND METHODS: Two hundred fifty samples of wheat, rice, corn, pistachios, and peanuts were collected from the five different locations of Tehran between January 2018 and January 2019. The samples were analyzed by using direct seed inoculation method and grain crushing method. Fungal strains were identified as Aspergillus spp. on the basis of morphological characters and further confirmed by using of β-tubulin gene sequencing. To differentiate between aflatoxigenic and non-aflatoxigenic Aspergillus spp., the isolates were screened for the presence of aflatoxigenic genes (nor-1, ver-1, omtA, and aflR). RESULTS: One-handed forty-eight aflatoxigenic Aspergillus isolates (144 A. flavus and 4 A. parasiticus) were identified and aflR gene was the most frequent gene in these species. Five isolates (4 A. flavus, 1 A. parasiticus) had quadruplet pattern, 64 isolates (63 A. flavus, 1 A. parasiticus) had more than 1 gene and 39 isolates (38 A. flavus,1 A. parasiticus) did not have any genes. CONCLUSION: According to the contamination of dried nuts and grains by some aflatoxigenic fungi, an extensive surveillance is necessary to provide a wider view on these products. Moreover, effective and efficient aflatoxin control program requires identifying and managing key elements that are effective in reducing mycotoxin production at farm level or in storage conditions.

Aim: Due to the high prevalence of sickle cell anemia and beta-shaped sickle cell thalassemia in this region, we decided to conduct this study with the aim of investigating the status of pulmonary function in these patients in Bandar Abbas. Method: The statistical population in this study included all patients with sickle cell anemia and sickle cell beta-thalassemia who had referred to the hematology clinic from 2019-2020, which was equal to 60 people. Also, the workers who had referred to the specialized lung clinic for periodic health tests entered the study by observing the criteria for leaving the review as a control group. Participants were subjected to spirometry and pulmonary volumes were measured. Result: The patients in the case group, 39 (65%) were from sickle cell anemia, and 21 (35%) were from the sickle cell beta-thalassemia. In this study, all the studied parameters had a significant difference between the study group and the control, except for the mean age (p=0.906). In the control group, the values of FEV1 (Forced expiratory volume in 1 second), FVC (Forced vital capacity), and FEF25-75% (Forced expiratory flow 25-75%) are higher than these values in the case group, and this difference is significant (P

Fundamental quantum-physical effects are nowadays harnessed in practical devices through different means. On the one hand, quantum potential boxes can be employed to alter electronic or photonic properties depending on the application. From bulk to zero-dimensional structures, the quantisation of energy states for physical entities, such as electrons or photons, gets pronounced and the density of states is strongly modified based on the dimensionality of the host system. Therefor, the size of a confinement potential provided by a host structure is typically adjusted to the length scale corresponding to the respective particle’s spatial extent, resulting in a quantum structure. Generally, quantum structures can be beneficial for optoelectronic or quantum devices due to several aspects, such as strong spatial confinement, tailored energy transport or storage, efficient lasing or nonclassical light generation, and altered interactions of their particles with their environment or other particles. On the other hand, the control of quantum coupling phenomena or the use of many-body effects can enable novel devices or open up new pathways to a fundamental exploration of quantum effects, such as hybridisation, superposition, collective phenomena and cavity quantum electrodynamics. Thus, this chapter aims at an introduction to prominent effects of size reduction to the nanoscale for electronics or microscale for photonics, as well as a summary of benefits and applications, giving examples from optoelectronics and nanophotonics.

Photonic applications of nanomaterials and quantum structures heavily rely on light–matter interactions and effective utilisation of their remarkable optical or optoelectronic properties. Typically, excitons in solids are coupled in one form or another to propagating or confined electromagnetic waves, i.e. either weakly or strongly, and interact with different kind of resonances present in their host medium. In addition, a tailored density-of-states for the electronic or the optical system through confinement potentials is commonly exploited to alter the coupling or dissipation behaviours of charge carriers or photons. Moreover, hybridisation of modes can occur which gives access to favourable properties for bosonic quasi-particles in solids. Many of these modifications and adjustments can be harnessed in photonic devices and fundamental studies of light–matter coupled oscillators, which can even undergo a phase transition towards a Bose–Einstein-like condensate in a solid-state platform. Light is shed on matter excitations in semiconductors in this chapter, with a focus on their interactions with photonic modes and peculiarities in monolayer materials. Furthermore, cavity–polaritons are discussed with eyes towards condensation phenomena and the influence of external fields. Particularly, polariton experiments involving terahertz waves are motivated.

Quantum technologies are an emerging field one can think of in two categories. The first generation, which used principles of quantum physics to deliver technologies of the last century, and the second generation, which harnesses quantum phenomena to achieve novel device functionalities in the current century. In general, various sophisticated tools for the control and manipulation of quantum states are required and under development, fundamental concepts based on nonclassical behaviour or properties are used, or new capabilities are enabled which would have been out of reach for classical devices. Indeed, the role of semiconductor photonics as well as quantum structures is pronounced. In this chapter, two aspects of work in the field of quantum technologies are summarised. The first part will deal with coherent light sources, ranging from semiconductor lasers to novel sources of coherent light. The second part provides an introduction into quantum optics based on quantum light generation and tailored light–matter coupling. Serving as a starting point, here given examples shall motivate further reading in the dedicated literature on these subjects.

The characterisation as well as improvement of various photonic devices, functional nanomaterials and quantum structures heavily relies on advanced optical tools. These tools typically incorporate suitable light sources and detection schemes to probe properties of the target system optically. Through special measurement techniques, one can for instance obtain optical images with high spatial resolution to map features of a sample, or read out spectral properties with sufficient temporal resolution in order to achieve insights into charge-carrier dynamics. While in many situations, the basic material response is of interest when irradiating light onto a sample, some techniques address a material’s nonlinearities or composition, the emission’s coherence or angle-dependencies, or a structure’s phonon modes or magneto-optical properties. In this chapter, numerous optical measurement techniques are summarised which can be useful in the field of semiconductor photonics, particularly with an emphasis on the characterisation of two-dimensional semiconductors and quantum structures. Here, practical examples from the author’s works may encourage further reading of expert literature on these subjects.

The class of two-dimensional materials has emerged as an important field within nanomaterials science, and quantum-materials research has caught the attention of various research communities. With the rise of graphene as a promising ultrathin, electronic and optoelectronic, flexible and robust material, the exploration of other similar van-der-Waals materials in the monolayer regime came into focus about a decade ago. Among them are the semiconducting 2D crystals of the transition-metal dichalcogenide family, the features of which can be typically even improved in combination with the atomically-flat 2D insulator hexagonal boron nitride. Currently, the characterisation, growth and utilisation of monolayers, as well as heterostructures thereof, are heavily targeted owing to their extraordinary properties and the prospects of device miniaturisation, as well as functionality boosts, in different technological domains. This chapter summarises various aspects of this material class with a focus on 2D semiconductors and their application examples with relation to the fields of (opto)electronics, photonics, as well as quantum technologies. An overview is given on the remarkable features of these 2D materials from both a fundamental and application-oriented perspective. A brief discussion of graphene and related materials is embedded. Here, also the role of stacked layered materials as well as heterostructuring is introduced, before subjects such as light–matter interactions and lasing with 2D semiconductors are addressed.

Lead toxicity is hindering the applications of conventional lead halide perovskites (PVKs), and antimony (Sb) is a promising nontoxic Pb alternative, showing huge potential in optoelectronic devices. Herein, pure and Mn-doped Cs

Studies show that warm mix asphalt (WMA) technology is a practical solution against the high production temperature of rubberized-asphalt (RA) mixtures. RA mixture containing WMA additive is considered as an eco-friendly technology contributing to noise reduction and performance optimization of asphalt mixtures. This study aims to introduce two organic WMA additives called slack wax (SW) and polypropylene wax (PPW) which are used to lower the production temperatures by reducing the viscosity of RA mixtures. Rotational viscosity (RV) as a common bitumen test (Equiviscous, ZSV, and S-ZSV methods), as well as tests related to mixtures including resilient modulus (Mr) and moisture susceptibility (TSR and MRR methods), were carried out on binder and mixture specimens. According to the results, 6% (by the binder’s weight) of both WMA additives reduced the mixing and compaction temperatures of the RA binder by about 20–25 °C. Also, CRM and both WMA additives improved the stiffness of mixtures by increasing the resilient modulus (Mr). In terms of moisture susceptibility, although nearly all specimens could pass the minimum requirement of SCDOT, both WMA additives and CRM caused a reduction in ITS value of wet mixtures and final TSR value. MRR test results followed a similar trend, though resilient modulus was more sensitive to moisture damage compared to ITS. The results suggest that PPW and SW are suitable and cost-effective warm additives that can be used in combination with CRM in areas with hot climates and low precipitation. Nevertheless, additional experiments should be done to further validate the performance of CRM mixtures with these two warm additives.

A theoretical variation between the two distinct light–matter coupling regimes, namely weak and strong coupling, becomes uniquely feasible in open optical Fabry—Pérot microcavities with low mode volume, as discussed here. In combination with monolayers of transition-metal dichalcogenides (TMDCs) such as WS2, which exhibits a large exciton oscillator strength and binding energy, the room-temperature observation of hybrid bosonic quasiparticles, referred to as exciton–polaritons and characterized by a Rabi splitting, comes into reach. In this context, our simulations using the transfer-matrix method show how to tailor and alter the coupling strength actively by varying the relative field strength at the excitons’ position – exploiting a tunable cavity length, a transparent PMMA spacer layer and angle-dependencies of optical resonances. Continuously tunable coupling for future experiments is hereby proposed, capable of real-time adjustable Rabi splitting as well as switching between the two coupling regimes. Being nearly independent of the chosen material, the suggested structure could also be used in the context of light–matter-coupling experiments with quantum dots, molecules or quantum wells. While the adjustable polariton energy levels could be utilized for polariton-chemistry or optical sensing, cavities that allow working at the exceptional point promise the exploration of topological properties of that point.

We measure both nonlinear absorption and nonlinear refraction in a ${{\rm CH}_3}{{\rm NH}_3}{{\rm PbBr}_3}$CH

Background: While many dental procedures induce pulpal damage by increase the temperature, this study was established to evaluate the thermally effect of different laser methods on pulp, oral soft and hard tissues. Objectives: In this study, laser irradiation applied to measure how increased in power output can influence on dental pulp by using CT images. Methods: Ten adult New Zealand white rabbits were divided into 2 groups receiving 3 and 5 watt for 15 second respectively on left side cheek teeth after shortening of third upper and first lower premolars. Right cheek teeth trimmed as well and served as control. CT scans were taken immediately after lasing and repeated every week for one month. Results: The statistical analysis of dental measurements shows that teeth length of right and left third upper premolar was significantly different during time (P0.05). Only third upper premolar in fourth week showed a significant difference between two groups (P=0.047). Conclusions: laser radiation could influence on tooth growth in both groups. This study revealed that the higher laser power would have been more effective on reduction of growth rate of teeth. In addition, 3D CT scans could be an appropriate tools for dental growth investigation.

We report on a comprehensive experimental analysis of the influence of the environment on the optical properties of monolayer WSe2. Different dielectric-environmental configurations with hBN as buffer and encapsulant were studied at room temperature and 10 K using time-integrated and time-resolved photoluminescence spectroscopy. Furthermore, Raman signal was evaluated to highlight the influence of the surroundings on the monolayer system. Here, linewidth and intensity improvement for 2D excitons as a consequence of hBN-encapsulation is demonstrated, and a change of strain and doping levels in our produced structures are observed. The increase of the exciton radius for hBN-buffered samples in comparison to WSe2 on bare substrates is indicated via an exciton–exciton annihilation study, while hBN as buffer is found to generally shorten the effective radiative lifetime. Furthermore, we report that trions experience a weaker interaction with the WSe2 phonons than excitons, while the coupling to phonons is consistently decreased when WSe2 is capped by hBN. Ultimately, our energy-resolved analysis of the dynamics at 10 K shows that the individual excitonic modes exhibit different photoluminescence decay times. A comparison of the different hBN-WSe2 configurations shows that the shortest measurable time constants, which are on the ps-scale, generally increase when buffering or encapsulating the 2D semiconductor, while sandwiching caused the strongest lifetime increase on these short time scales. In contrast, our monolayer–monolayer heterostructures indicate fast charge/energy transfer (

2D-materials, especially transition metal dichalcogenides (TMDs) have drawn a lot of attention due to their remarkable characteristics rendering them a promising candidate for optical applications. While the basic properties are understood up to now, the influence of the environment has not been studied in detail, yet. Here we highlight a systematic comparison of the optical properties of tungsten diselenide monolayers on different substrates. Subtle changes in the emission spectrum and Raman signature have been found as well as surprisingly pronounced differences in the pump-power-dependent and time-resolved output at higher excitation densities. For all samples, exciton–exciton annihilation can be obtained. Nevertheless an analysis of different pump-dependent decay rates suggests substrate-dependent changes in the diffusion constant as well as exciton Bohr radius.

Lactobacillus is a cariogenic microorganism. Different therapeutic approaches including photodynamic therapy (PDT) have been suggested for treatment of bacterial infection. The purpose of the current study was to compare the effects of PDT with Indocyanine green (ICG) and Methylene blue (MB) photosensitizers (PSs) on Lactobacillus acidophilus (L. acidophilus).In this in-vitro experimental study, 84 samples of L. acidophilus (1 McFarland standard) were compared in 14 experimental groups including: MB, ICG, 660-nm laser, 808-nm laser (pulsed, 74s/continuous-wave, 37s), different combinations of lasers and PSs, Chlorhexidine (CHX) 0.2%, sodium hypochlorite (NaOCl) 2.5%, penicillin 6.3.3 and control groups. The samples were cultured in microplates containing blood agar culture medium. After incubation at 37 °C for 48 h, the colony forming units (CFUs) of L. acidophilus were counted and compared before and after therapeutic interventions. Data were analyzed using SPSS19 software program according to one-way ANOVA test.This study showed that the separate use of ICG, 660- and 808-nm lasers (pulsed, 74s/continuous-wave, 37s), and the combined use of 808-nm laser (pulsed, 74s/continuous-wave, 37s) and ICG have no significant inhibitory effect on L. acidophilus colonies (P 0.05), whereas the separate use of MB and the combined use of 660-nm laser (continuous-wave, 37s/pulsed, 74s) and MB significantly inhibited the growth of L. acidophilus in comparison with the control group (p 0.05). Likewise, CHX 0.2%, NaOCl 2.5% and penicillin 6.3.3 significantly inhibited the bacterial growth (p 0.05).The results showed that separate use of MB and combined use of 660-nm laser and MB have a significant inhibitory effect on L. acidophilus growth.

Typically, strong gain saturation and gain dynamics play a crucial role in semiconductor laser mode-locking. While there have been several investigations of the ultrafast gain dynamics in vertical-external-cavity surface-emitting lasers (VECSELs), little is known about the associated refractive index changes. Yet, such refractive index changes do not only have a profound impact on the pulse formation process leading to self-phase modulation, which needs to be compensated by dispersion, but they are also of particular relevance for assessing the feasibility of Kerr-lens mode-locking of VECSELs. Here, we measure both refractive index as well as gain dynamics of a VECSEL chip using the ultrafast beam deflection method. We find that, in contrast to the gain dynamics, the refractive index dynamics is dominated by an instantaneous ($\sim$100~fs) and a very slow component ($\sim$100~ps). The time-resolved measurement of nonlinear refraction allows us to predict a pulse-length dependent, effective nonlinear refractive index $n_{2,eff}$, which is shown to be negative and in the order of $10^{-16}$ $m^2/W$ for short pulse lengths ($\sim$100~fs) . It becomes positive for large excitation fluences and large pulse lengths (few ps). These results agree with some previous reports of self-mode-locked VECSELs for which the cavity design and pulse properties determine sign and strength of the nonlinear refractive index when assuming Kerr-lens mode-locking.

Agricultural commodities contaminated by molds and mycotoxins can be considered as public health problems in less developed countries, particularly in Iran. Hence the main purpose of this study was to identify mold fungi and molecular analysis of the most important species of aflatoxin-B1-producingTwo hundred fifty samples of wheat, rice, corn, pistachios, and peanuts were collected from the five different locations of Tehran between January 2018 and January 2019. The samples were analyzed by using direct seed inoculation method and grain crushing method. Fungal strains were identified asOne-handed forty-eight aflatoxigenicAccording to the contamination of dried nuts and grains by some aflatoxigenic fungi, an extensive surveillance is necessary to provide a wider view on these products. Moreover, effective and efficient aflatoxin control program requires identifying and managing key elements that are effective in reducing mycotoxin production at farm level or in storage conditions.

Owing to a complex monocline structure and high-density of defects in monocrystalline GaTe, the performance of GaTe-based electronic devices is considerably compromised. Yet, the defects’ nature in GaTe could be a merit rather than a shortcoming in other realms. In our work, the density of defects in GaTe films is utilized for a facile decoration of Au nanoparticles (NPs), which allowed us to extend its application potential to the domain of surface enhanced Raman scattering (SERS) for the first time. Two-dimensional (2D) GaTe layered structures are prepared by mechanical exfoliation, and high-density Au NPs are synthesized by immersion of 2D GaTe in HAuCl4 aqueous solution. By varying the immersion time, the sizes and coverage rate of Au NPs on GaTe can be elaborately tuned. Thanks to the defect nature of GaTe, the maximum coverage amounts to 98%. The hereby achieved Au-NPs–2D-GaTe hybrid structure demonstrates outstanding properties as a superior SERS substrate for ultrasensitive detection of R6G aromat...

By virtue of the surface plasmon resonance effect, plasmonic nanoparticles (NPs) can localize the light field and significantly enhance the performance of some optoelectronic devices. In this work, NPs are employed for an enhanced generation of terahertz radiation from LT-GaAs-based antennas. Therefore, we have prepared plasmonic TiN NPs by direct ultrasonication (ULS) and pulsed laser ablation (PLA) techniques. The zeta potential, particle size, and absorbance were used to characterize the NPs in their colloidal forms in a comparison to commercial Au NPs. A layer of polydispersed titanium nitride (TiN) NPs prepared by PLA and deposited on the surface of an LT-GaAs device shows a significant improvement of terahertz signal generation from these devices with an enhancement of the peak to peak amplitude of 100%.

For polaritons, the phase transition to a macroscopically-occupied ground-state has attracted immense attention in the research community given the fact that exciton–polaritons in microcavities are ideal testbeds for investigations of many-particle physics in solids. As composite bosons formed out of the strong light–matter coupling in quantum-well microcavity systems, they enjoy prominent features such as a very light effective mass and thereby an elevated critical temperature for BEC when compared to other experimentally available particles for such studies. Being part light and part matter, their excitation, dynamics and condensation behaviour deserves special consideration. Firstly, bosonic many-particle features such as BEC and the effect of stimulated ground-state scattering will be explained. Consecutively, excitation and relaxation dynamics are discussed, which are fundamental to polariton condensation. In this context, the significance of overcoming the so-called relaxation bottleneck towards the ground state will be explained and stimulated scattering into a macroscopically occupied Bose state discussed.

Strong light–matter coupling has given rise to fascinating phenomena and observations in the past decades. The emergence of the field of polaritonics has been particularly evidenced since sophisticated microcavity experiments allowed the realization and investigation of Bose–Einstein-like condensation of exciton–polaritons and the superfluid nature of degenerate Bose gases in solids. Thus, this chapter summarizes the history and the developments regarding polariton research and provides an introduction to the following chapters. Hereby, the concept of Bose–Einstein condensation of polaritons and endeavors to achieve polariton lasers within the wider framework of polariton studies are also briefly highlighted.

External fields such as magnetic or electric fields are widely used to manipulate and control quantum emitters in semiconductor structures based on their magnetic or electronic response. Since coupling of the light field to an emitter is governed by a few factors, such as resonance conditions, the oscillator strength of electric dipoles, and selection rules, external fields with their effects on the spatial wave-function overlap, the dipole orientation, spin degeneracy or resonance energies directly affect light–matter interaction. Some properties can be for instance electrically manipulated through band structure tilts and fields using tunable external bias, whereas the magnetic moment and spin properties of excitations in matter can be addressed with variable magnetic fields. Typically, static fields are employed, whereas transient fields can be used as a tool for additional control of the quantum state on ultrafast time scales. Many examples of polariton experiments clearly show that the rich polariton physics in optical microcavities can be further studied when exposing the exciton–polaritons to external fields. Prominent effects of external fields on excitons and, consequently, on polaritons will be summarized in the following.

We measure nonlinear refraction and absorption of a CH3NH3PbBr3 single crystal with the Z-scan technique. Our results provide the first reference of the intrinsic, ultrafast nonlinear refractive index in the metal halide perovskite material class.

Light–matter interaction is a prerequisite for the observation of polaritons and for the utilization of excitonic particles in optical devices. It is particularly essential to deal with the recipe for strong coupling of excitons and photons in this early chapter to provide the necessary theoretical background for the dealings with the following content. Firstly, the principles of light–matter interaction will be introduced and the building blocks of polariton formation presented. Thereafter, the composite boson given by the quasi-particle polariton will be discussed and its general properties will be summarized. Here, the important role of the cavity–exciton detuning in optical microcavities with quantum-well excitons is sufficiently discussed in order to establish the necessary understanding of its impact on the quasi-particles’ behaviour for later considerations of polariton condensates.

Polariton-laser research has attracted a considerable amount of attention in the last decade and has led to remarkable insight into the physics of QW microresonators and exciton–polariton s. Technological advances allowed the design and fabrication of more precise and more suitable structures until the demonstration of the long desired effect of polariton condensation was observed. Since then, a plethora of condensate studies has been performed utilizing polaritons. As a driven-dissipative system, polaritons constantly decay, delivering a stream of coherent photons out of a quantum-degenerate state, and need to be refilled to uphold the quasi-condensate regime. Different examples of a polariton laser have been presented, both optically and electrically pumped, and even operated up to room temperature. However, the idea of a laser-kind device which utilizes bosonic polaritons and their phase transition into a macroscopically-occupied quantum-degenerate gas was proposed years before, back in the 1990s. This led to the birth of a new class of coherent light sources, named “polariton laser”. In the following, the principles of such a device are summarized, and its differences and similarities to conventional lasers and the means of identification for an unambiguous demonstration of polaritonic lasing explained.

The observation of polariton condensation with the help of high-quality optical microcavities was a long sought goal in solid-state research. Optical pumping of planar microresonator structures consisting of multiple quantum wells as active region offers a common and direct path towards exciton–polariton studies. After obtaining spectral proof of polaritons in the linear regime, which describes the response at low-density excitation, the behaviour of a polariton gas at increased particle densities gets naturally into the focus, where stimulated scattering is expected to set in. The demonstration of a condensate is typically linked to signatures such as a macroscopic ground-state occupation, a change in the photon statistics and a spontaneous build-up of long-range order evidenced as spatial coherence. Indeed, to establish the link to BEC , all aspects must be carefully investigated. These topics are subject of this chapter, which concludes with examples of condensates at elevated temperature, polariton systems with special features and superfluidity studies on polariton condensates.