High-power terahertz pulse generation from bias-free nanoantennas on graded composition InGaAs structures.

We present a bias-free photoconductive emitter that uses an array of nanoantennas on an InGaAs layer with a linearly graded Indium composition. The graded InGaAs structure creates a built-in electric field that extends through the entire photoconductive active region, enabling the efficient drift of the photo-generated electrons to the nanoantennas. The nanoantenna geometry is chosen so that surface plasmon waves are excited in response to a 1550 nm optical pump to maximize photo-generated carrier concentration near the nanoantennas, where the built-in electric field strength is maximized. With the combination of the plasmonic enhancement and built-in electric field, high-power terahertz pulses are generated without using any external bias voltage. We demonstrate the generation of terahertz pulses with 860 µW average power at an average optical pump power of 900 mW, exhibiting the highest radiation power compared to previously demonstrated telecommunication-compatible terahertz pulse emitters.

[One-Year Candida Data of the Central Mycology Laboratory: Which Sample, Which Species, How Resistant?] / Merkez Mikoloji Laboratuvarinin Bir Yillik Candida Verileri: Hangi Örnek, Hangi Tür, Ne Kadar Dirençli?

The incidence of fungal infections particularly Candida species, is increasing gradually as a result of the increased life expectancy associated with the advances in the diagnosis and treatment of diseases, and increased number of patients in the risk group over the years. In addition, the incidence of fungal infection types that are resistant to antifungal drugs has been increasing, and rare fungal species have been reported to be isolated more frequently. For this reason, it is indicated that identification to the species level will contribute to the early initiation of an accurate and effective treatment. In this study, it was aimed to define the Candida species isolated from various clinical specimens and to document the performance of antifungal sensitivity tests. The Candida isolates sent to the central mycology laboratory in 2019 for identification and antifungal susceptibility tests were included in the study. The definition of the fungi to the species level was carried out using matrix-assisted laser desorption ionization-time of fl ight mass spectrometry (MALDI-TOF MS) and conventional methods. In vitro antifungal drug susceptibilities were analyzed using the The Clinical and Laboratory Standarts Institute (CLSI, M27-A3) reference broth microdilution method. The minimum inhibitory concentration (MIC) results were interpreted in accordance with the species-specific clinical breakpoints (CBPs) cited in the CLSI-M60 guidelines, and according to the epidemiological cut-off value (ECV) when no CBP was mentioned. The distribution of the species of the total 813 Candida isolates included in the study were as follows: Candida albicans (n= 312 ), Candida parapsilosis (n= 202), Candida tropicalis (n= 92), Candida glabrata (n= 71), Candida dubliniensis (n=28), Candida lusitaniae (n= 26), Candida kefyr (n= 22), Candida utilis (n= 17), Candida krusei (n= 14), Candida orthopsilosis (n= 7), Candida inconspicua (n= 7), Candida guilliermondii (n= 5), Candida metapsilosis (n= 4), Candida norvegensis (n= 4), Candida lambica (n= 1) and Candida lipolytica (n= 1). The evaluation of the results of the antifungal susceptibility tests according to the CBPs revealed that one C.albicans isolate and 60 C.parapsilosis (29.7%) isolates were resistant, and seven C.parapsilosis (3.5%) isolates were dose-dependent susceptible to fluconazole; 32 C.parapsilosis (15.8%) isolates were intermediately susceptible to voriconazole; one C.parapsilosis (0.5%) was resistant and one C.krusei (7.1%) was intermediately susceptible to anidulafungin; and one C.parapsilosis (0.5%) was resistant and one C.krusei (7.1%) isolate was intermediately susceptible to micafungin. In terms of ECVs, one C.lusitaniae isolate for fluconazole and one of each C.lusitaniae and C.kefyr isolates were evaluated as a non-wild type. In the present study, 61 of 813 isolates were found to be resistant to fluconazole and seven were dose dependently susceptible, 32 were intermediately susceptible to voriconazole, one was resistant to anidulafungin, one was intermediately susceptible, and one was resistant to micafungin and one was intermediately susceptible to micafungin. In conclusion, the increased number of non- albicans Candida species and increased levels of resistance to antifungal drugs further establish the importance of early diagnosis at a species level alongside antifungal susceptibility tests.

High-sensitivity telecommunication-compatible photoconductive terahertz detection through carrier transit time reduction.

We present a telecommunication-compatible photoconductive terahertz detector realized without using any short-carrier-lifetime photoconductor. By utilizing plasmonic contact electrodes on a thin layer of high-mobility photoconductor, the presented detector offers a short transit time for the majority of the photocarriers in the absence of a short-carrier-lifetime photoconductor. Consequently, high-sensitivity terahertz detection is achieved with a record-high signal-to-noise ratio of 122 dB over a 3.6 THz bandwidth under an optical probe power of 10 mW. To achieve such a high sensitivity, the device geometry is chosen to maintain a high resistance and low Johnson Nyquist noise. This design approach can be widely applied for terahertz detection using various semiconductors and optical wavelengths, without being limited by the availability of short-carrier-lifetime photoconductors.

Plasmonics-enhanced photoconductive terahertz detector pumped by Ytterbium-doped fiber laser.

We present a photoconductive terahertz detector operating at the 1 µm wavelength range at which high-power and compact Ytterbium-doped femtosecond fiber lasers are available. The detector utilizes an array of plasmonic nanoantennas to provide sub-picosecond transit time for the majority of photo-generated carriers to enable high-sensitivity terahertz detection without using a short-carrier-lifetime substrate. By using a high-mobility semiconductor substrate and preventing photocarrier recombination, the presented detector offers significantly higher sensitivity levels compared with previously demonstrated broadband photoconductive terahertz detectors operating at the 1 µm wavelength range. We demonstrate pulsed terahertz detection over a 4 THz bandwidth with a record-high signal-to-noise ratio of 95 dB at an average terahertz radiation power of 6.8 µW, when using an optical pump power of 30 mW.

High-efficiency ultrafast optical-to-electrical converters based on InAs nanowire-plasmonic arrays.

There has been a growing interest in developing high-efficiency ultrafast optical-to-electrical converters for advanced imaging and sensing applications. Here, we propose a three-dimensional (3D) plasmonic platform based on InAs nanowire arrays with self-assembled gold gratings, which converts a telecom-wavelength (1550 nm) optical beam to sub-picosecond current pulses with quantum efficiency up to 18.3%, while operating in photovoltaic mode, i.e., at zero bias. Using a comprehensive 3D photoresponse model, we reveal that the incident photons form tightly confined fields near the gratings at nanowire tips, and thus a majority of the photogenerated carriers are efficiently routed to the metal within a few tens of nanometers distance, resulting in ultrafast current pulses. In addition, we show that the amplitude of current pulses is robust to the nanowire surface quality and can be effectively tuned by varying the doping levels in nanowires. This work paves a way to realizing a low-power, highly compact, and low-cost device scheme for ultrafast pulse generation.

The frequency, antifungal susceptibility and enzymatic profiles of Candida species in cases of onychomycosis infection.

Although the frequency of candidal onychomycosis is increasing daily, there is little information in literature about the epidemiology, pathogenesis, and antifungal susceptibility of this dermatological disease. This study aimed to provide information about the epidemiology, pathogenesis, and azole susceptibility of Candida species isolated from patients living in a region with continental climate. After identification of the isolated strains using conventional methods, proteinase and phospholipase activities were determined by a plate method and biofilm-forming ability was determined using the microplate method. Susceptibility of the same species to fluconazole (FLU), voriconazole (VRC), miconazole (MNZ), itraconazole (ITZ), and ketoconazole (KTZ) were determined by microdilution method. The 50 Candida isolates included 23 C. parapsilosis (46%), 13 C. albicans (26%), 4 C. guilliermondii(8%), 4 C.tropicalis (8%), 2 C.krusei(2%), 1 C.lusitaniae (2%), 1 C. sake (2%), and 1 C. kefyr (2%) isolates. The geometric mean (GM) of the minimum inhibitory concentration (MIC) for FLU, KTZ, VRC, MNZ, and ITZ was 0.4 µg/mL, 0.08 µg/mL, 0.08 µg/mL, 0.2 µg/mL, and 0.6 µg/mL, respectively. Proteinase, phospholipase, and biofilm-forming ability were detected in 18%(9/50), 20%(10/50), and 6%(3/50) of the Candida isolates, respectively. We found that the most frequently isolated species is C.parapsilosis. On the basis of the GM values, the most effective azoles are ketoconazole and voriconazole. The isolated Candida species exhibited low phospholipase, proteinase, and biofilm formation activities.

Evaluation of the first Candida auris isolates reported from Türkiye in terms of identification by various methods and susceptibility to antifungal drugs.

PURPOSE: Candida auris is increasingly being isolated from patients all over the world. It has five clades. In this study, it was aimed to compare the results of biochemical tests obtained using different methods and the antifungal susceptibility profiles of C. auris strains isolated from the first seven cases reported in Türkiye, and evaluate whether this information could be useful as preliminary data in determining the clade of strains in centers that lack the opportunity to apply molecular methods. METHODS: Identification test results obtained using API ID 32 C, API 20 C AUX, VITEK-2 YST, and MALDI-TOF MS; colony color and morphology on Chromagar Candida, CHROMagar Candida Plus media, and cornmeal-Tween 80 agar; susceptibility to antifungals were tested and compared. Antifungal susceptibility test was studied using microdilution method according to the recommendations of EUCAST. Additionally, a pilot study was conducted to investigate the value of CHROMagar Candida Plus. RESULTS: All seven strains were identified as Lachancea kluyveri with API ID 32 C, Rhodotorula glutinis; Cryptococcus neoformans with API 20 C AUX, and C. auris with both VITEK-2 YST and MALDI-TOF MS. MIC values for fluconazole were very high (≥64 mg/L) for all seven strains. It was observed that 11 (37.9%) of 29 Candida parapsilosis strains formed colonies with morphology similar to C. auris on CHROMagar Candida Plus medium, leading to false positivity. CONCLUSIONS: Although there have been many isolations of C. auris in our country in recent years, clade distribution of only a small number of strains is known yet. In this study, when the biochemical properties and antifungal susceptibility profiles of the seven strains were evaluated, it was concluded that they exhibited some characteristics compatible with clade I. It was also observed that strains 1 and 2 may belong to a different clade.

Birth expectations, birth experiences and childbirth-related post-traumatic stress symptoms in mothers and birth companions: Dyadic investigation using response surface analysis.

OBJECTIVES: During the perinatal period, women and their birth companions form expectations about childbirth. We aimed to examine whether a mismatch between birth expectations and experiences predict childbirth-related post-traumatic stress symptoms (CB-PTSS) for mothers and birth companions. We also explored the influence of the mismatch between mothers' and birth companions' expectations/experiences on CB-PTSS. DESIGN: Dyadic longitudinal data from the Self-Hypnosis IntraPartum Trial. METHODS: Participants (n = 469 mothers; n = 358 birth companions) completed questionnaires at 27 and 36 weeks of gestation and 2 and 6 weeks post-partum. We used the measures of birth expectations (36 weeks gestation), birth experiences (2 weeks post-partum) and CB-PTSS (6 weeks post-partum). RESULTS: Correlations revealed that birth expectations were associated with experiences for both mothers and birth companions but were not consistently associated with CB-PTSS. Birth experiences related to CB-PTSS for both mothers and birth companions. The response surface analysis results showed no support for the effect of a mismatch between expectations and experiences on CB-PTSS in mothers or birth companions. Similarly, a mismatch between mothers' and birth companions' expectations or experiences was unrelated to CB-PTSS. CONCLUSIONS: Following previous literature, birth expectations were associated with experiences, and experiences were associated with CB-PTSS. By testing the effect of the match between birth experiences and expectations using an advanced statistical method, we found that experiences play a more substantial role than the match between experiences and expectations in CB-PTSS. The impact of birth experiences on CB-PTSS highlights the importance of respectful and supportive maternity care.

Phenotypic Investigation of Virulence Factors, Susceptibility to Ceragenins, and the Impact of Biofilm Formation on Drug Efficacy in Candida auris Isolates from Türkiye.

Candida auris has emerged as a significant fungal threat due to its rapid worldwide spread since its first appearance, along with its potential for antimicrobial resistance and virulence properties. This study was designed to examine virulence characteristics, the efficacy of ceragenins, and biofilm-derived drug resistance in seven C. auris strains isolated from Turkish intensive care patients. It was observed that none of the tested strains exhibited proteinase or hemolysis activity; however, they demonstrated weak phospholipase and esterase activity. In addition, all strains were identified as having moderate to strong biofilm formation characteristics. Upon determining the minimum inhibitory concentrations (MIC) of ceragenins, it was discovered that CSA-138 exhibited the highest effectiveness with a MIC range of 1-0.5 µg/mL, followed by CSA-131 with a MIC of 1 µg/mL. Also, antimicrobial agents destroyed mature biofilms at high concentrations (40-1280 µg/mL). The investigation revealed that the strains isolated from Türkiye displayed weak exoenzyme activities. Notably, the ceragenins exhibited effectiveness against these strains, suggesting their potential as a viable treatment option.

Coherent terahertz radiation with 2.8-octave tunability through chip-scale photomixed microresonator optical parametric oscillation.

High-spectral-purity frequency-agile room-temperature sources in the terahertz spectrum are foundational elements for imaging, sensing, metrology, and communications. Here we present a chip-scale optical parametric oscillator based on an integrated nonlinear microresonator that provides broadly tunable single-frequency and multi-frequency oscillators in the terahertz regime. Through optical-to-terahertz down-conversion using a plasmonic nanoantenna array, coherent terahertz radiation spanning 2.8-octaves is achieved from 330 GHz to 2.3 THz, with ≈20 GHz cavity-mode-limited frequency tuning step and ≈10 MHz intracavity-mode continuous frequency tuning range at each step. By controlling the microresonator intracavity power and pump-resonance detuning, tunable multi-frequency terahertz oscillators are also realized. Furthermore, by stabilizing the microresonator pump power and wavelength, sub-100 Hz linewidth of the terahertz radiation with 10-15 residual frequency instability is demonstrated. The room-temperature generation of both single-frequency, frequency-agile terahertz radiation and multi-frequency terahertz oscillators in the chip-scale platform offers unique capabilities in metrology, sensing, imaging and communications.

[The relationship between antibiotic resistance and virulence factors in urinary Enterococcus isolates]. / Üriner Enterokok Izolatlarinin Antibiyotik Direnci ile Virülans Faktörleri Arasindaki Iliski.

Increasing multidrug resistance in nosocomial Enterococcus strains from all over the world recently enhances the need for further investigation of enterococci, especially their virulence factors. There are still many lacking parts about virulence factors of clinical enterococcus isolates. In this study, it was aimed to investigate the antibiotic resistance and the presence of potential virulence factors of 91 Enterococcus strains (59 E.faecalis, 31 E.faecium and 1 E.gallinarum) isolated from urine cultures of inpatients between January 2008-June 2010 in our hospital and also to evaluate whether a correlation existed between antibiotic resistance and potential virulence factors. The genes which encoded virulence factors of enterococci; aggregation substance (AS), enterococcal surface protein (ESP) and hyaluronidase (HYL) (asa1, esp, hyl respectively) were studied by molecular methods and haemolysin production and gelatinase activity were studied by phenotypic methods. Vancomycin resistant strains were checked for the presence of vanA and vanB genes. Eight (25.8%) E.faecium isolates were found glycopeptide resistant. In seven of these isolates resistance type was vanA and in one it was neither vanA nor vanB. High-level gentamicin and high-level streptomycin resistance rates were 74.2% and 61.3% in E.faecium strains and were 22% ve 27.1% in E.faecalis strains, respectively. Beta-lactamase production and linezolid resistance were not detected in any of the strains. E.faecium isolates were more resistant (p< 0.001-0.013) than E.faecalis isolates to all tested antibiotics except tetracycline, minocycline, doxycycline and streptogramin (p< 0.001). hyl gene positivity (p< 0.001) was found higher in E.faecium isolates whereas esp (p= 0.003) and asa1 (p< 0.001) gene positivity, haemolysin production (p=0.014) and gelatinase activity (p= 0.029) were higher in E.faecalis isolates. AS and ESP were the most frequent virulence factors, with the rates of 26.7% and 25.6%, respectively. There were 32 (35.6%) strains without any of the investigated virulence factors. We have also detected that asa1 gene positive E.faecalis isolates were more resistant to ciprofloxacin (p= 0.001), norfloxacin (p= 0.006) and levofloxacin (p= 0.001) than asa1 gene negative isolates; esp gene positive E.faecalis isolates were more resistant to doxycycline (p= 0.043) than esp gene negative isolates and hyl gene positive E.faecium isolates were more resistant to nitrofurantoine (p= 0.011) than hyl gene negative isolates. This was the first clinical sample originated study, investigating the corelation between antibiotic resistance and virulence factors in urinary Enterococcus isolates in Turkey.

Effects of calcineurin inhibitors, cyclosporine A and tacrolimus (FK506), on the activity of antifungal drugs against Candida spp.

Introduction. The simultaneous use of antifungals with immunosuppressive agents has become a necessity for patients taking immunosuppressive therapy. However, antifungal drugs are problematic because of their limited target.Hypothesis. Scientists have been searching for new antifungals and some compounds with at least additive effects on antifungals. Calcineurin inhibitors used as immunosuppressive agents also attract attention due to their antifungal property.Aim. To evaluate the activity of two calcineurin inhibitors alone and in combination with amphotericin B (AMB), caspofungin (CAS), itraconazole (ITR), voriconazole (VOR) and fluconazole (FLU).Methodology. MICs of AMB, CAS, ITR, VOR, FLU and cyclosporine A (CsA) and tacrolimus (TAC) as calcineurin inhibitors were evaluated by the broth microdilution method against Candida albicans (n=13), C. krusei (n=7) and C. glabrata (n=10). Checkerboard and time-kill methods were performed to investigate the activity of combining calcineurin inhibitors with antifungal drugs.Results. The lowest MIC values were detected with VOR for all Candida isolates tested. Although we did not detect any inhibition for CsA or TAC alone at concentrations tested in this study, the combinations of CAS with CsA showed the highest synergistic activity (36.7%) by the checkerboard method, and CAS with CsA and ITR with TAC combinations exhibited apparent synergistic interaction by the time-kill method. However, the combinations of both CsA and TAC with AMB resulted in antagonistic interactions, especially against C. krusei isolate in time-kill testing.Conclusion. Synergistic interactions in the combinations of TAC or CsA with antifungal drugs, except for AMB, in many concentrations was found to be promising in terms of the treatment of patients with fungal infections.

Wavelength conversion through plasmon-coupled surface states.

Surface states generally degrade semiconductor device performance by raising the charge injection barrier height, introducing localized trap states, inducing surface leakage current, and altering the electric potential. We show that the giant built-in electric field created by the surface states can be harnessed to enable passive wavelength conversion without utilizing any nonlinear optical phenomena. Photo-excited surface plasmons are coupled to the surface states to generate an electron gas, which is routed to a nanoantenna array through the giant electric field created by the surface states. The induced current on the nanoantennas, which contains mixing product of different optical frequency components, generates radiation at the beat frequencies of the incident photons. We utilize the functionalities of plasmon-coupled surface states to demonstrate passive wavelength conversion of nanojoule optical pulses at a 1550 nm center wavelength to terahertz regime with efficiencies that exceed nonlinear optical methods by 4-orders of magnitude.

The impact of the molecular weight of dextran on formation of whey protein isolate (WPI)-dextran conjugates in fibers produced by needleless electrospinning after annealing.

The conjugation reaction of electrospun fibers of a mixture of whey protein isolate (WPI) and dextran using different molecular weights (40, 70, and 100 kDa) and mixing ratios was studied. This study includes the electrospinnability of a mixture of WPI and dextran, and the conjugation reaction between them via the initial stage of the Maillard reaction. The WPI-dextran fibers were characterized using optical and transmission electron microscopy. The covalent attachment of dextran to WPI was confirmed using sodium-dodecyl-sulfate-polyacrylamide gel-electrophoresis with protein and glycoprotein staining. Both 70 and 100 kDa of dextran and WPI at mixing ratios of 2 : 1 and 3 : 1 in phosphate buffer (30 mM, pH 6.5) were electrospun using needleless electrospinning. The solution concentration of the mixture was 50 wt% (33.3/37.5 wt% for dextran/16.5/12.5 wt% for WPI). The optimal conjugation conditions chosen from the experiments were a mixture of dextran (70 kDa)-WPI at 3 : 1 (75% relative humidity, 60 °C, 48 h).

In vitro susceptibility of seven antifungal agents against dermatophytes isolated in Istanbul

Background/aim: Dermatophytes are the causative agents of dermatophytosis, which is a common disease worldwide that affects the hair, skin, and nails. Dermatophytes comprise more than 40 species in 3 genera: Microsporum, Trichophyton, and Epidermaphyton. In this study, we aimed to determine the effectiveness of seven antifungal agents: amphotericin B, terbinafine, itraconazole, voriconazole, ketoconazole, miconazole, and fluconazole. Materials and methods: A sensitivity study was performed using a microdilution method in accordance with the CLSI M38-A2 standards using isolates of Trichophyton rubrum (n = 55), Microsporum canis (n = 9), and Trichophyton interdigitale (n = 2), which were identified by sequencing the internal transcribed spacer region of the rDNA. Results: According to the results of antifungal sensitivity tests, the geometric mean (GM) minimum inhibitory concentration (MIC) against T. rubrum was 0.10 µg/mL for ketoconazole, 0.20 µg/mL for itraconazole, 0.07 µg/mL for miconazole, 0.48 µg/mL for fluconazole, 2.27 µg/mL for amphotericin B, 0.06 µg/mL for voriconazole, and 0.06 µg/mL for terbinafine. Conclusion: The most effective antifungal drugs were voriconazole and terbinafine, both of which had a GM MIC of 0.06 µg/mL.

The role of dermoscopy in the diagnosis of distal lateral subungual onychomycosis.

Recently dermoscopic patterns, that can be useful in the diagnosis of distal and lateral subungual onychomycosis, were identified. In this study, we aimed to determine the frequency of the defined patterns so far and additionally to identify other patterns that were observed and to investigate the place of these patterns in the diagnosis of Distal Lateral Subungual Onychomycosis (DLSO) in the dermoscopic examination of the patients with pre-diagnosis of DLSO. Patients admitted dermatology outpatient clinic of Haydarpasa Numune Training and Research Hospital with the complaint of nail disturbance suspicious for DLSO (97 patients) between the August 2015 and February 2016. Clinical and dermoscopic photographs of the cases with a pre-diagnosis of DLSO were taken and their nails were cut for pathological examination and culture. In hematoxylin and eosin, and periodic acid schiff examination, hyphe and/or spore were observed in 134 (65.4%) and fungal growth was detected in 99 (48.3%) of the nail samples. As a result of logistic regression model analysis, the p values of the 'ruin appearance', 'homogeneous leukonychia', 'punctate leukonychia', and 'black discoloration' patterns preserved their statistical significance (p = 0.015, p = 0.009, p = 0.026, p = 0.040, respectively). We believe that in nail disorders clinically resembling DLSO patients, the presence of dermoscopic patterns of ruin appearance, homogenous leuconychia, punctate leuconychia, and black discoloration strongly supports the clinical diagnosis of DLSO.

The influence of thermal processing on emulsion properties of defatted hazelnut flour.

In this study, the influences of roasting and the amount of hazelnut flour on the formation and stabilization of emulsions containing different amounts of oil were investigated. After hazelnuts were roasted in an oven at 140°C for 40 min, the oil content was removed. The emulsions with defatted hazelnut flour containing corn oil at 3%, 10% and 50% were prepared. Roasting process significantly decreased the interfacial tension values of samples down to 1.9 mN/m due to protein denaturation. There was no significant difference between the particle sizes of oil droplets in emulsions with roasted and raw hazelnut flour at the same concentration. However, diffusion coefficients of oil droplets increased for emulsions containing roasted defatted flour samples. The zeta (ζ) potential values of all emulsions increased when roasted hazelnut flour was used, indicating the stabilization of suspensions and the solution resistance against aggregation. Storage modulus (G'), loss modulus (G″) and complex viscosity (η(∗)) of emulsions were measured. G' value was found to be greater than the G″ value, which fits into weak gel model. The roasting process resulted with lower transition temperatures but with increased transition enthalpies of the flour samples based on differential scanning (DSC) measurements. Lower transition temperatures may be attributed to the partial gelatinization of starch in the flour and partial denaturation of proteins. These results may help to tailor the properties of defatted hazelnut flour when it is used in food products containing emulsions such as sauces, dressings and creams for stabilizing purposes.