Diffusion of Photoexcited Holes in a Viscous Electron Fluid.

The diffusion of photogenerated holes is studied in a high-mobility mesoscopic GaAs channel where electrons exhibit hydrodynamic properties. It is shown that the injection of holes into such an electron system leads to the formation of a hydrodynamic three-component mixture consisting of electrons and photogenerated heavy and light holes. The obtained results are analyzed within the framework of ambipolar diffusion, which reveals characteristics of a viscous flow. Both hole types exhibit similar hydrodynamic characteristics. In such a way the diffusion lengths, ambipolar diffusion coefficient, and the effective viscosity of the electron-hole system are determined.

Growth and formation mechanism of shape-selective preparation of ZnO structures: correlation of structural, vibrational and optical properties.

A shape-selective preparation method was used to obtain highly crystalline rod-, needle-, nut-, and doughnut-like ZnO morphologies with distinct particle sizes and surface areas. We study the nucleation and growth mechanism of those structures and the influence of physical-chemical parameters, such as the solvent and the pH of the solution, on the morphology, as well as the structural and optical properties. A clear correlation between the growth rate along the c-axis and surface defects was established. Our results suggest that the needle- and rod-like morphologies are formed due to the crystal growth orientation along the c-axis and the occurrence of crystalline defects, such as oxygen vacancies and interstitial Zn2+ located at the surface, whereas nuts and doughnuts are formed due to growth along all crystalline planes except those related to growth along the c-axis. Based on the experimental results, growth mechanisms for the formation of ZnO structures were proposed. We believe this synthetic route will be of guidance to prepare several materials whose shapes will depend on the desired applications.

An extremely rare case of an oversized accessory spleen: case report and review of the literature.

BACKGROUND: The accessory spleen is a congenital defect characterized by a separated ectopic splenic parenchyma. The size is rarely more than 4 cm. The preoperative diagnosis is prohibitive preoperatively. The aims of the present manuscript were to present the case of a patient with a rare oversize accessory spleen and a review of the literature. CASE PRESENTATION: A 15-year-old boy was admitted to the emergency department following blunt abdominal trauma. The computed tomographic scan showed a traumatic rupture of the spleen and a 7-cm mass at the left side of the retroperitoneal space. Conservative treatment started and aborted after 4 h due to the onset of haemodynamic instability. Splenectomy was performed. An accessory spleen was discovered. A second large mass in the retroperitoneum was diagnosed as a second large accessory spleen that was also left in place. The postoperative course was uneventful, and the patient was discharged on the 7th postoperative day. Seven months later, the CT scan showed viability of both accessory spleens. CONCLUSION: An accessory spleen can be variously located and the retroperitoneal position is extremely uncommon. Preoperative diagnosis is still difficult, especially in emergency and as in our case, the literature shows the difficulty of reaching a diagnosis before surgery. The main misdiagnosis is neoplastic disease and for this reason accessory spleen can be wrongly removed. An undiagnosed pre or intra operative retroperitoneal mass, closely to the spleen, have to be managed carefully. The diagnosis of accessory spleen needs to be ever considered as if found, represents a great possibility to conduct a normal life after splenectomy (of main spleen) for trauma.

A new modified Mayo technique: should the surgeons need a new open technique for hernia repair in their armamentarium?

INTRODUCTION: The Mayo technique is one of the most common techniques used to repair incisional, umbilical, and epigastric hernias. A high percentage of recurrences, together with the use of particular expensive types of meshes, are some of the most relevant problems in this surgical field. PATIENTS AND METHODS: This study is a clinical prospective observational and involves all the patients who underwent procedures using a new modified Mayo technique from 2006 through 2013. The general criteria analyzed were age, sex, obesity, smoke abuse, diabetes, chronic diseases, type of hernia, operative time, morbidity and mortality. All the patients involved in this study were followed-up from 6 to 120 months. RESULTS: The types of hernia were 5 epigastic hernia (20,8%), 8 umbilical hernia (33,3%), 11 midline incision hernia (45,9%). Ten patients (41,7%) presented non-complicated hernias; 8 patients (33,3%) presented strangulated hernias and 6 patients (25,0%) presented obstructed hernias. No intestinal resection was necessary in any of the patients. The mean operative time was 55 minutes (range 30-180). The mean hospital stay of the patients' after-post operative procedure was 4.5 days (range, 2 to 8 days). No major complications have been reported. Only one patient present a recurrence. CONCLUSION: These preliminary results suggest that this modified Mayo technique could be useful in the armamentarium of surgeon to repair incisional, umbilical, and epigastric hernias. More studies are needed to validate the technique.

Participation of TLR2 and TLR4 in Cytokines Production by Patients with Symptomatic and Asymptomatic Chronic Chagas Disease.

Chagas disease (CD), caused by the protozoan Trypanosoma cruzi, is a serious public health issue. Its evolution involves an acute stage, characterized by no specific symptoms, and the chronic stage during most individuals are asymptomatic, but about 30-40% of them become symptomatic presenting the cardiac or digestive disease. Host immune response mechanisms involved in symptomatic or asymptomatic chronic disease are not fully understood. The pro-inflammatory cytokines are crucial in host resistance. However, a fine control of this inflammatory process, by action of anti-inflammatory cytokines, is necessary to avoid tissue injury. This control was found to be responsible for no clinical manifestations in asymptomatic individuals. Toll-like receptors (TLRs) are extremely important in defining the cytokine profile released in response to a micro-organism. We found that patients with the cardiac form predominantly released the pro-inflammatory cytokines: IFN-γ, TNF-α and IL-17 with the involvement of both, TLR2 and TLR4. In contrast, patients with asymptomatic disease release predominantly the anti-inflammatory cytokines IL-10 and TGF-ß, but also with TLR2 and TLR4 participation. The mechanisms by which stimulation of the same TLRs results in release of different pattern of cytokines, depending on the patients group that is being evaluated, are discussed.

Synthesis of Pr3+-doped WO3 particles: correlation between photoluminescent and photocatalytic properties.

The WO3 and WO3:Pr3+ particles were successfully synthesized by the co-precipitation method. The XRD analysis with Rietveld refinement revealed the formation of a monoclinic phase for WO3 and for doped samples, this result was later confirmed by Raman spectroscopy studies. The presence of Pr3+ in the WO3 crystalline lattice induced structural and optical changes in the particles, increasing the crystallite size, distorting the clusters (shortening of the W-O bonds), favoring the crystallinity and changing the optical gap. The predominant morphology of the particles of WO3 and WO3:Pr3+ obtained was nanocubes constituted by the superposition of plates of nanometric thicknesses. The photoluminescence of WO3 and WO3:Pr3+ was produced by the existence of surface defects in the particles. The increase in the concentration of Pr3+ promoted an increase in the intensity of PL, due to the increase in the rate of recombination of electron/hole charges. The WO3 sample exhibited emission in the white region due to the adjustment of simultaneous electronic transitions in the blue, green and red regions, characteristic of the broadband spectrum. The interval of the 2.65 eV gap band and the high efficiency in the separation of the photogenerated charges (e-/h+) with the low recombination rate contributed to the photocatalytic degradation of Crystal Violet (CV) by the catalyst. The WO3:4% Pr3+ sample showed the best photocatalytic efficiency, degrading 73% of the CV dye in 80 minutes. This result was associated with a reduction in particle size and density of oxygen vacancies on the material surface.

[Chronic pelvic pain in patients with endometriosis: results of laparoscopic treatment]. / Dolore pelvico cronico nell'endometriosi: risultati del trattamento laparoscopico.

AIM: The chronic pelvic pain (CPP) linked to endometriosis, relatively frequent condition in women of reproductive age, often represents the main complaint for which the patient seeks medical advice. The purpose of this prospective study was to evaluate if and to which extent systematic ablation of endometriotic lesions causes an improvement and/or disappearance of pain in patients with ascertained endometriosis and in whom the main preoperative symptom is chronic pelvic pain. METHODS: This study examined 109 patients, affected by chronic pelvic pain secondary to endometriosis, underwent laparoscopic treatment. All patients in the preoperative phase and only the 92 coming back for follow up, were asked both to fill out an anonymous questionnaire about their quality of life and to indicate on a numeric visual analogue scale (VAS) the intensity of the perceived pain. RESULTS: Overall the median of the VAS score for pain decreased from 7.5 before surgery to 2.5 at one-year postoperative-follow up, which was consistent (Wilcoxon test) with a statistically significant regression (P<0.0001) of the intensity of perceived pain (disappearance or marked reduction) in the operated patients, independently from the stage of the disease and the type of pain; also data on quality of life during work and social activity indicated a relevant improvement respectively in 82% and in 83% of patients following the laparoscopic procedure. CONCLUSION: For this reason and as suggested by the present international guidelines, when the medical therapy against pain fails and/or in the presence of an adnexal mass (chocolate cyst) or deep endometriotic lesion, it is generally correct to rely on surgical ablation of the lesions preferably by laparoscopy.

Photocatalytic degradation of methylene blue and dye mixture using indium-doped CaWO4 synthesized by sonochemical and microwave-assisted hydrothermal methods.

This study presents indium-doped calcium tungstate for the first time. The photocatalytic and photoluminescent properties of pure and In3+ doped samples were investigated. All pure and indium-doped calcium tungstate particles were synthesized for 30 minutes by two different methods: the sonochemical method (SM) and the microwave-assisted hydrothermal method. The nanoparticles were characterized by X-ray diffraction (XRD), field emission gun-scanning electron microscopy (SEM-FEG), UV-Visible spectroscopy, Brunauer-Emmett-Teller method, and zeta potential analysis. The diffractogram results confirmed the formation of scheelite crystalline structures without forming deleterious phases. The SEM-FEG images show the powder with irregular morphology and agglomerated as rods and kibes. For both methods, samples with 8% In3+ ions showed lower PL intensities with maximum peaks at 479 and 483 nm, suggesting lower e-/h+ pair recombination, which led these samples to present better photocatalytic performance. The photocatalytic activity was estimated from the degradation of the methylene blue (MB) dye under UV light and the sample stability was tested in 3 reuse cycles. The scavenger methodology indicated that h+ is the most active mechanism in the photocatalysis process. The degradation of the dye mixture (MB, MO, and RhB dyes) was also performed.

Correction: Synthesis and evaluation of photocatalytic and photoluminescent properties of Zn2+-doped Bi2WO6.

Correction for 'Synthesis and evaluation of photocatalytic and photoluminescent properties of Zn2+-doped Bi2WO6' by L. X. Lovisa, et al., Dalton Trans., 2022, https://doi.org/10.1039/d2dt03175b.

Revealing the impact of strain in the optical properties of bubbles in monolayer MoSe2.

Strain plays an important role for the optical properties of monolayer transition metal dichalcogenides (TMDCs). Here, we investigate strain effects in a monolayer MoSe2 sample with a large bubble region using µ-Raman, second harmonic generation (SHG), µ-photoluminescence and magneto µ-photoluminescence at low temperature. Remarkably, our results reveal the presence of a non-uniform strain field and the observation of emission peaks at lower energies which are the signatures of exciton and trion quasiparticles red-shifted by strain effects in the bubble region, in agreement with our theoretical predictions. Furthermore, we have observed that the emission in the strained region decreases the trion binding energy and enhances the valley g-factors as compared to non-strained regions. Considering uniform biaxial strain effects within the unit cell of the TMDC monolayer (ML), our first principles calculations predict the observed enhancement of the exciton valley Zeeman effect. In addition, our results suggest that the exciton-trion fine structure plays an important role for the optical properties of strained TMDC ML. In summary, our study provides fundamental insights on the behaviour of excitons and trions in strained monolayer MoSe2 which are particularly relevant to properly characterize and understand the fine structure of excitonic complexes in strained TMDC systems/devices.

Monitoring of Cr, Cu, Pb, V and Zn in polluted soils by laser induced breakdown spectroscopy (LIBS).

Laser Induced Breakdown Spectroscopy (LIBS) is a fast and multi-elemental analytical technique particularly suitable for the qualitative and quantitative analysis of heavy metals in solid samples, including environmental ones. Although LIBS is often recognised in the literature as a well-established analytical technique, results about quantitative analysis of elements in chemically complex matrices such as soils are quite contrasting. In this work, soil samples of various origins have been analyzed by LIBS and data compared to those obtained by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). The emission intensities of one selected line for each of the five analytes (i.e., Cr, Cu, Pb, V, and Zn) were normalized to the background signal, and plotted as a function of the concentration values previously determined by ICP-OES. Data showed a good linearity for all calibration lines drawn, and the correlation between ICP-OES and LIBS was confirmed by the satisfactory agreement obtained between the corresponding values. Consequently, LIBS method can be used at least for metal monitoring in soils. In this respect, a simple method for the estimation of the soil pollution degree by heavy metals, based on the determination of an anthropogenic index, was proposed and determined for Cr and Zn.

Electron-phonon coupling enhancement and displacive magnetostructural transition in SrCr2 As2 under magneto-Raman spectroscopy.

A Raman spectroscopy study on high quality single crystals of SrCr2 As2 (SCA) in the temperature T range 4 K < T < 300 K and high applied magnetic fields up to H = 9 T is presented. The chromium B 1g phonon analysis reveals two anomalous shifts in the frequency, the first below T = 250 K at H = 0 T in the saturated AFM G-type order likely due to an enhanced electron-phonon coupling by the magnetic order, whereas the second anomaly occurs above H = 4 T at T = 4 K likely as a consequence of a magnetostructural displacive transition. Renormalization of the electronic Raman spectra in both studies reveals a decrease in the electronic density of states with decreasing T and increasing H, respectively, with consequent changes in the Fermi surface, which are intrinsically related to the observed anomalies.

Aharonov-Bohm interference in neutral excitons: effects of built-in electric fields.

We report a comprehensive discussion of quantum interference effects due to the finite structure of neutral excitons in quantum rings and their first experimental corroboration observed in the optical recombinations. The signatures of built-in electric fields and temperature on quantum interference are demonstrated by theoretical models that describe the modulation of the interference pattern and confirmed by complementary experimental procedures.

Effects of bias voltage on diamond like carbon coatings deposited using titanium isopropoxide (TIPOT) and acetylene/argon mixtures onto various substrate materials.

RF-PECVD was used to prepare amorphous of carbon (DLC) onto stainless steel 316 and glass substrates. The substrates were negatively biased at between 100 V to 400 V. Thin films of DLC have been deposited using C2H2 and titanium isopropoxide (TIPOT). Argon was used to generate the plasma in the PECVD system chamber. DEKTAK 8 surface stylus profilometer was used to measure the film thickness and the deposition rate was calculated. Micro Raman spectroscopy was employed to determine the chemical structure and bonding present in the films. Composition analysis of the samples was carried out using VGTOF SIMS (IX23LS) instrument. In addition, X-ray photoelectron spectroscopy (XPS) was used to analyze the composition and chemical state of the films. The wettability of the films was examined using the optical contact angle meter (CAM200) system. Two types of liquids with different polarities were used to study changes in the surface energy. The as-grown films were in the thickness range of 200-400 nm. Raman spectroscopy results showed that the I(D)/I(G) ratio decreased when the bias voltage on the stainless steel substrates was increased. This indicates an increase in the graphitic nature of the film deposited. In contrast, on the glass substrates the I(D)/I(G) ratio increased when the bias voltage was increased indicates a greater degree of diamond like character. Chemical composition determined using XPS showed the presence of carbon and oxygen in both samples on glass and stainless steel substrates. Both coatings the contact angle of the films decreased except for 400 V which showed a slight increase. The oxygen is thought to play an important role on the polar component of a-C.

[Innovative genetic, clinical and endocrinologic aspects in young females affected by premature ovarian insufficiency]. / Innovativi aspetti genetici, clinici ed endocrini in una giovane popolazione femminile affetta da insufficienza ovarica prematura.

AIM: Heterogeneity premature ovarian insufficiency (POI) is one of the reasons why there are different causes that contribute in determining this type of hormonal disorder. Although the causes have already been established for many types of premature ovarian failure, are still uncertain causes in most cases of idiopathic forms, despite the description of several candidate genes, including BMP-15 gene. The gene under study is precisely the BMP-15, which is part of the superfamily of Transforming Growth Factors-beta or the TGF-ß, which also belong to the growth differentiation factors (GDFs). METHODS: This study examined a sample of Sicilian women suffering from POI, carefully selected according to their age, since in these cases, the genetic factor probably has a greater impact. RESULTS AND CONCLUSION: Identify a mutant gene that causes ovarian failure may be important to make a diagnosis that can predict the possible future development of the disease. The outcome of the studies, however, has not found the gene in question, but it is hypothesized that this may be a direct consequence of the limited amount of women that was done the study, a case which may be rebutted by increasing the number of patients.

Protection of ovarian tissue from radiotherapy.

Advances researches in the diagnosis and treatment of childhood, adolescent and adult cancer have greatly increased the life expectancy of premenopausal women with cancer. However, one of the serious side effects of these treatments is the risk of damage to fertility. The ovaries are very sensitive to cytotoxic and radiotherapeutic treatment. The only established method of fertility preservation is embryo cryopreservation according to the Ethics Committee of the American Society for Reproductive Medicine (2005), but this option requires the patient to be of pubertal age, have a partner or use donor sperm, and be able to undergo a cycle of ovarian stimulation, which is not possible when the radiotherapy has to be initiated immediately or when stimulation is contraindicated according to the type of cancer. For patients who need immediate radiotherapy, cryopreservation of ovarian tissue is the only possible alternative. This manuscript reports the different techniques of cryopreservation and the results of transplantation of cryopreserved ovarian tissue. The current techniques allow cryopreservation of human ovarian fragments for a long time with good follicular survival rate after thawing. Numerous studies ultimately in this field have demonstrated to improve the survival rate of the oocytes and cryopreserved follicles. Moreover this manuscript includes a case of a 17-year-old girl who had to undergo pelvic irradiation for non-Hodgkin's lymphoma and the laparoscopic treatment to preserve the fertility (Fig. 2, Ref. 47).

Open conversion for laparoscopically difficult cholecystectomy is still a valid solution with unsolved aspects.

The difficult laparoscopic cholecystectomy remains a surgical challenge for surgeons who must decide between laparoscopic continuation and open conversion. The balance between the lack of open surgery training of young surgeons and the risk of maintaining the laparoscopic approach in difficult laparoscopic cholecystectomy is still an unresolved problem. Furthermore, the time that must be spent in an attempt to complete laparoscopic surgery before conversion is still controversial. The authors in this letter discuss about these and other questions that still require an answer.

Methylated arsenic species throughout a 4-m deep core from a free-floating peat island.

Arsenic (As) occurs in soils mostly in inorganic forms, whereas the organic forms usually occur only in trace amounts. Peatlands are waterlogged, generally anoxic, organic soils representing the first step in coal formation; the contribution of organic vs. inorganic As species in this environment has received little research attention. Here, 57 peat samples collected throughout a 4-m deep, free-floating mire were analysed for total As and for its organic species, including dimethylarsinic acid (DMA), methylarsonic acid (MA), trimethylarsine oxide (TMAO) and arsenobetaine (AB), by HPLC-ICPMS. Aqueous trifluoroacetic acid was used as extractant, resulting in an average extraction efficiency of almost 80%. Total As concentration throughout the profile ranged between 0.2 and 9.8mg/kgpeat (mean: 1.4±1.2mg/kgpeat). Organic As species (DMA+MA+TMAO+AB) accounted, on average, for 28±10% of total As (range: 6-51%), and for 37±13% of the extracted As (range: 7-64%). The relative abundance of organoarsenicals generally followed the order DMA>TMAO~MA≫AB. A positive correlation (p<0.001) was found among all organic As compounds, whereas their concentrations were negatively correlated with total sulfur content. The submerged zone (bottom 300cm) showed average and maximum concentrations of organoarsenic compounds that were almost twice those found in the top 100cm. This study shows that significant proportions of methylated As species occur even in peat samples characterized by low total As concentration (mostly <2mg/kg). Finally, this work provides the first evidence of organoarsenic species in free-floating mires, i.e., a globally distributed but scarcely investigated ecosystem.

Highly anomalous accumulation rates of C and N recorded by a relic, free-floating peatland in Central Italy.

Floating islands mysteriously moving around on lakes were described by several Latin authors almost two millennia ago. These fascinating ecosystems, known as free-floating mires, have been extensively investigated from ecological, hydrological and management points of view, but there have been no detailed studies of their rates of accumulation of organic matter (OM), organic carbon (OC) and total nitrogen (TN). We have collected a peat core 4 m long from the free-floating island of Posta Fibreno, a relic mire in Central Italy. This is the thickest accumulation of peat ever found in a free-floating mire, yet it has formed during the past seven centuries and represents the greatest accumulation rates, at both decadal and centennial timescale, of OM (0.63 vs. 0.37 kg/m2/yr), OC (0.28 vs. 0.18 kg/m2/yr) and TN (3.7 vs. 6.1 g/m2/yr) ever reported for coeval peatlands. The anomalously high accretion rates, obtained using 14C age dating, were confirmed using 210Pb and 137Cs: these show that the top 2 m of Sphagnum-peat has accumulated in only ~100 years. As an environmental archive, Posta Fibreno offers a temporal resolution which is 10x greater than any terrestrial peat bog, and promises to provide new insight into environmental changes occurring during the Anthropocene.

Characterization of water extractable organic matter in a deep soil profile.

The aim of this study was to identify qualitative and quantitative differences of water extractable organic matter (WEOM) isolated from each horizon along a deep soil profile and to evaluate any relationship between the WEOC and the total organic carbon (TOC) content. The soil profile "Monte Pietroso" is located in the Murge area, Apulia region in Southern Italy. Samples from the eight horizons (Ap1, Ap2, Ab1, Ab2, Bt1, 2B, 2Bt2, and 2B/C) were collected in October 2002. The WEOM characterization was carried out by means of UV absorbance, fluorescence spectroscopy in the emission and excitation/emission matrix (EEM) modes, and additional spectroscopic derived indexes. Soil organic carbon was shown to accumulate in the top horizons (Ap) and, in general, to decrease with depth, whereas, the WEOM/TOC ratio increases with increasing depth. The aromaticity and the humification index of the WEOM decrease dramatically downward the soil profile, whereas the fluorescence efficiency index tends to increase markedly. The WEOM fractions feature three main fluorophores with different wavelength and relative intensity. In general WEOM transport phenomena are suggested to occur downward the soil profile, depending on the nature of the organic material and on the chemical and mineral characteristics of the various horizons.