Effects of COVID-19 on the Liver and Mortality in Patients with SARS-CoV-2 Pneumonia Caused by Delta and Non-Delta Variants: An Analysis in a Single Centre

The aim of this study was to ascertain patient characteristics, outcomes, and liver injuries in patients infected with different SARS-CoV-2 variants. Data from consecutive adult patients with severe/critical COVID-19 admitted to our hospital during the peak month of the Delta wave were compared to the ancestral, Alpha, and Omicron waves. The dataset of 551 hospitalized patients was similar in the Delta/non-Delta waves. At admission and discharge, the median aminotransferase levels were normal or slightly increased. During the Delta wave (172 vs. 379 non-Delta patients), more patients died (OR 1.69, 95%CI 1.09-2.56) or had liver injury at discharge (alanine aminotransferase, ALT ≥ 2 ULN) (OR 1.97, 95%CI 1.08-3.54). In-hospital mortality was associated with age, lung injury, intensive care unit admission, number of and cardiovascular comorbidities, diabetes, chronic kidney disease, and all inflammatory biomarkers. Serious liver injury at admission (ALT ≥ 5 × ULN) was significantly associated with in-hospital mortality (OR = 7.9, 95%CI 2-28.9). At discharge, drug-induced liver injury (DILI) was found in patients treated with remdesivir, ALT ≥ 2 ULN (OR = 2.62, 95%CI 1.22-5.75). Treatment with dexamethasone, remdesivir, and immunomodulators showed improved survival, OR = 0.50 (95%CI 0.33-0.77). Regardless of the variant and treatment options, less than 2% of patients displayed serious liver injury, which was not found to be a death predictor in multivariable analysis.

Evolving Clinical Manifestations and Outcomes in COVID-19 Patients: A Comparative Analysis of SARS-CoV-2 Variant Waves in a Romanian Hospital Setting

The aim of this study was to evaluate differences in the clinical manifestations and outcomes in hospitalized patients with COVID-19 in a single Romanian center during four pandemic waves determined by different SARS-CoV-2 variants of concern (VOCs). A retrospective study on 9049 consecutive hospitalized adult patients was performed between 27 February 2020 and 31 March 2023. The study interval was divided into waves based on national data on SARS-CoV-2 VOCs' circulation. Multivariate logistic regression models were built, predicting death and complications as functions of comorbidities, therapy, wave, severity form, and vaccination status, and adjusted for ages ≥65 years. Pulmonary (pneumothorax/pneumomediastinum, pulmonary embolism) and extrapulmonary complications (liver injury, acute kidney injury, ischemic/hemorrhagic stroke, myocardial infarction, and gastrointestinal bleeding) were present, more frequently in ICU hospitalized patients and with differences between waves. The highest in-hospital mortality was found in patients presenting pneumothorax/pneumomediastinum. All of the evaluated risk factors were significantly associated with death, except for obesity and the Omicron wave. Our study highlights the changing nature of COVID-19 and acknowledges the impacts of viral mutations on disease outcomes. For all four waves, COVID-19 was a severe disease with a high risk of poor outcomes.

Treatment with Tocilizumab in Adult Patients with Moderate to Critical COVID‐19 Pneumonia: A Single‐Center Retrospective Study

Objectives

This study aimed to assess if tocilizumab (TCZ) timing is associated with improved survival.

Material and methods

Data obtained from adult patients with moderate/severe/critical COVID-19 and treated with TCZ, who were admitted to the Teaching Hospital of Infectious Diseases, Cluj-Napoca, Romania (April 2020-April 2021), were retrospectively analyzed. The database included demographics, clinical data, computed tomography scan results, the kinetics of IL-6, laboratory variables, and the outcome until discharge.

Results

A total of 221 patients received dexamethasone, antivirals, anticoagulants, and 1-2 doses of TCZ, 8 mg/kg. In 2021, more patients received high-flow oxigen/non-invasive ventilation compared to those hospitalized in 2020, but demographics, in-hospital mortality, and laboratory data did not differ significantly. In-hospital mortality was associated with age, disease severity, lung damage, intensive care unit (ICU) admission, cardiovascular comorbidities, and IL-6>100 pg/mL at TCZ administration. In multivariate analysis the risk of death was significantly higher in patients with a persistent inflammatory state, adjusted odds ratio (aOR) 16.6 (95% CI 3.07-108.96); lung damage>40%, aOR 11.68 (95% CI 2.05-224.98); and cardiovascular comorbidities>2, aOR 3.65 (95% CI 1.06-12.53). TCZ initiation at ≤3 days after admission showed improved survival, odds ratio (OR)=0.39 (95% CI 0.16-0.9). Severe infections were found in 11 (4.9%) patients.

Conclusion

Early initiation of TCZ seems beneficial and safe in patients with moderate to critical COVID-19 pneumonia.

Bifractal structure of chromatin in rat lymphocyte nuclei

The small-angle neutron scattering (SANS) on the rat lymphocyte nuclei demonstrates the bifractal nature of the chromatin structural organization. The scattering intensity from rat lymphocyte nuclei is described by power law Q^{-D} with fractal dimension approximately 2.3 on smaller scales and 3 on larger scales. The crossover between two fractal structures is detected at momentum transfer near 10^{-1}nm^{-1}. The use of contrast variation (D_{2}O-H_{2}O) in SANS measurements reveals clear similarity in the structural organizations of nucleic acids (NA) and proteins. Both chromatin components show bifractal behavior with logarithmic fractal structure on the large scale and volume fractal with slightly smaller than 2.5 structure on the small scale. Scattering intensities from chromatin, protein component, and NA component demonstrate an extremely extensive range of logarithmic fractal behavior (from 10^{-3} to approximately 10^{-1}nm^{-1}). We compare the fractal arrangement of rat lymphocyte nuclei with that of chicken erythrocytes and the immortal HeLa cell line. We conclude that the bifractal nature of the chromatin arrangement is inherent in the nuclei of all these cells. The details of the fractal arrangement-its range and correlation/interaction between nuclear acids and proteins are specific for different cells and is related to their functionality.

Observation of nucleic acid and protein correlation in chromatin of HeLa nuclei using small-angle neutron scattering with D_{2}O-H_{2}O contrast variation

The small-angle neutron scattering (SANS) on HeLa nuclei demonstrates the bifractal nature of the chromatin structural organization. The border line between two fractal structures is detected as a crossover point at Q_{c}≈4×10^{-2}nm^{-1} in the momentum transfer dependence Q^{-D}. The use of contrast variation (D_{2}O-H_{2}O) in SANS measurements reveals clear similarity in the large scale structural organizations of nucleic acids (NA) and proteins. Both NA and protein structures have a mass fractal arrangement with the fractal dimension of D≈2.5 at scales smaller than 150 nm down to 20 nm. Both NA and proteins show a logarithmic fractal behavior with D≈3 at scales larger than 150 nm up to 6000 nm. The combined analysis of the SANS and atomic force microscopy data allows one to conclude that chromatin and its constitutes (DNA and proteins) are characterized as soft, densely packed, logarithmic fractals on the large scale and as rigid, loosely packed, mass fractals on the smaller scale. The comparison of the partial cross sections from NA and proteins with one from chromatin as a whole demonstrates spatial correlation of two chromatin's components in the range up to 900 nm. Thus chromatin in HeLa nuclei is built as the unified structure of the NA and proteins entwined through each other. Correlation between two components is lost upon scale increases toward 6000 nm. The structural features at the large scale, probably, provide nuclei with the flexibility and chromatin-free space to build supercorrelations on the distance of 10^{3} nm resembling cycle cell activity, such as an appearance of nucleoli and a DNA replication.

Antibody and viral RNA kinetics in SARS-CoV2 infected patients admitted to a Romanian University Hospital of Infectious Diseases

OBJECTIVES

To assess the antibody and viral kinetics in asymptomatic/mild confirmed SARS-CoV-2 infections compared to more severe patients.

MATERIAL AND METHODS

Retrospective analysis of data obtained from adult patients with a confirmed SARS-CoV2 infection having at least one SARS-CoV-2 pair of specific IgM/IgG tests, admitted in The University Hospital of Infectious Diseases Cluj-Napoca, Romania (28 February to 31 August 2020). The database also included: demographic, clinical, chest X-ray and/or CT scan results, RT-PCR SARS-CoV-2, and dexamethasone treatment. A total of 469 patients were evaluated as "asymptomatic/mild" and "moderate/severe/critical" cases.

RESULTS

The median time since confirmation to SARS-CoV-2 PCR negativity was 15 days [95% CI: 13-18] in asymptomatic/mild cases and 17 days [95% CI: 16-21] in moderate/severe ones. The median time to seroconversion for both IgM and IgG was 13 days [95% CI: 13-14] in asymptomatic/mild cases and 11 days [95% CI: 10-13] in moderate/severe ones. For both antibody types, the highest reactivity was significantly associated with more severe presentation (IgM: OR = 10.30, IgG: OR = 7.97).

CONCLUSION

Asymptomatic/mild COVID-19 cases had a faster RT-PCR negativity rate compared to moderate/severe/critical patients. IgG and IgM dynamics were almost simultaneous, more robust for IgG in more severe cases, and at one month after confirmation, almost all patients had detectable antibody titers.

Phase behavior of ultrasoft spheres show stable bcc lattices

The phase behavior of supersoft spheres is explored using solutions of ultralow cross-linked poly(N-isopropylacrylamide)-based microgels as a model system. For these microgels, the effects of the electric charges on their surfaces can be neglected and therefore only the role of softness on the phase behavior is investigated. The samples show a liquid-to-crystal transition at higher volume fraction with respect to both hard spheres and stiffer microgels. Furthermore, stable body centered cubic (bcc) crystals are observed in addition to the expected face centered cubic (fcc) crystals. Small-angle x-ray and neutron scattering with contrast variation allow the characterization of both the microgel-to-microgel distance and the architecture of single microgels in crowded solutions. The measurements reveal that the stable bcc crystals depend on the interplay between the collapse and the interpenetration of the external shell of the ultralow cross-linked microgels.

Switch of fractal properties of DNA in chicken erythrocytes nuclei by mechanical stress

The small-angle neutron scattering (SANS) on the chicken erythrocyte nuclei demonstrates the bifractal nature of the chromatin structural organization. Use of the contrast variation (D_{2}O-H_{2}O) in SANS measurements reveals the differences in the DNA and protein arrangements inside the chromatin substance. It is the DNA that serves as a framework that constitutes the bifractal behavior showing the mass fractal properties with D=2.22 at a smaller scale and the logarithmic fractal behavior with D≈3 at a larger scale. The protein spatial organization shows the mass fractal properties with D≈2.34 throughout the whole nucleus. The borderline between two fractal levels can be significantly shifted toward smaller scales by centrifugation of the nuclei disposed on the dry substrate, since nuclei suffer from mechanical stress transforming them to a disklike shape. The height of this disk measured by atomic force microscopy (AFM) coincides closely with the fractal borderline, thus characterizing two types of the chromatin with the soft (at larger scale) and rigid (at smaller scale) properties. The combined SANS and AFM measurements demonstrate the stress induced switch of the DNA fractal properties from the rigid, but loosely packed, mass fractal to the soft, but densely packed, logarithmic fractal.

Cold and distant: structural features of the nucleoprotein complex of a cold-adapted influenza A virus strain

Two influenza A nucleoprotein variants (wild-type: G102R; and mutant: G102R and E292G) were studied with regard to macro-molecular interactions in oligomeric form (24-mers). The E292G mutation has been previously shown to provide cold adaptation. Molecular dynamics simulations of these complexes and trajectory analysis showed that the most significant difference between the obtained models was distance between nucleoprotein complex strands. The isolated complexes of two ribonucleoprotein variants were characterized by transmission electron microscopy and differential scanning fluorimetry (DSF). Presence of the E292G substitution was shown by DSF to affect nucleoprotein complex melting temperature. In the filament interface peptide model, it was shown that the peptide corresponding in primary structure to the wild-type NP (SGYDFEREGYS) is prone to temperature-dependent self-association, unlike the peptide corresponding to E292G substitution (SGYDFGREGYS). It was also shown that the SGYDFEREGYS peptide is capable of interacting with a monomeric nucleoprotein (wild type); this interaction's equilibrium dissociation constant is five orders of magnitude lower than for the SGYDFGREGYS peptide. Using small-angle neutron scattering (SANS), the supramolecular structures of isolated complexes of these proteins were studied at temperatures of 15, 32, and 37 °C. SANS data show that the structures of the studied complexes at elevated temperature differ from the rod-like particle model and react differently to temperature changes. The data suggest that the mechanism behind cold adaptation with E292G is associated with a weakening of the interaction between strands of the ribonucleoprotein complex and, as a result, the appearance of inter-chain interface flexibility necessary for complex function at low temperature.Communicated by Ramaswamy H. Sarma.

Attitudes, practices, and priority of HIV screening and testing among clinical providers in Transylvania and Moldavia, Romania

Abstract

Screening and linkage to care are core, foundational strategies for HIV transmission prevention and for identifying People Living with HIV (PLHIV). In Romania – with an atypical experience in the HIV/AIDS epidemic – providing care for HIV+ patients identified early is a priority, though screening and testing can pose a challenge in some areas.

Methods

A survey of 125 clinical providers to explore important dimensions of HIV/ AIDS clinical care was conducted in Transylvania and Moldavia, where clinicians identified poor/ latent screening as a major problem in providing timely care and in preventing the spread of disease. We analyzed determinants of offering HIV screening/testing to patients using Pearson Chi-square analysis and logistic regression. Logistic regression generated Odds Ratios (OR) to reflect the magnitude of association between the relevant variables, with 95% confidence interval (95% CI) indicating statistical range.

Results

In total, 40.8% of providers did not provide HIV screening/testing to at least one segment of the population. Hospital-based providers were significantly more likely to offer HIV screening/testing to all segments than were non-hospital-based providers (58.1% v. 35.5%, respectively; p < .05). Providers located within institutions with screening/testing policies were more likely to offer such services to their patients (p < .05). Overall, 94.4% of providers indicated interest in more training around HIV screening/testing.

Discussion

Reaching Romanian and global goals for reducing HIV require more timely screening and action based on positive status. Romanian clinicians are interested in expanding HIV screening/testing and are interested in participating in training that helps them feel more prepared to undertake this work.

Access to digital and social media among Romanian HIV/AIDS clinical providers

The WHO/UNAIDS suggests that digital tools – such as social media and online training opportunities, can connect providers in difficult social and medical contexts to providers elsewhere for guidance, support, and advice. Social media is emerging as an innovative option for connecting clinicians together and for enhancing access to professional resources. In Romania, characterized by an atypical HIV/AIDS epidemic which is further challenged by a range of access complexities, it is unclear how often – and which kinds of – social media clinicians use to support clinical care. This study was conducted to ascertain social media use for clinical providers based in two regions of Romania (Transylvania and Moldavia) who face distance challenges that could potentially be alleviated by social media interaction. We used an online survey to understand what social media are currently popular and perceived to be useful for learning clinical information. Descriptive and bivariate analyses were conducted. Providers indicated Facebook and WhatsApp were the most common social media platforms, with 62% and 45% reporting daily use, respectively. Providers who used one media platform were significantly more likely to use another social media platform (p < .05). These data are helpful for creating an online training platform on HIV/AIDS for Romanian clinical providers.

Direct Assessment of Tube Dilation in Entangled Polymers

A key ingredient within theories focusing on the rheology of entangled polymers is the way how the topological constraints of an entangled chain are lifted by unconstrained segments, i.e., how the constraining tube is dilated. This important question has been addressed by directly measuring the tube diameter d at the scale of the tube by neutron spin echo spectroscopy. The tube diameter d and plateau modulus G_{N}^{0} of highly entangled polyethylene oxide (PEO) chains of volume fraction c that are diluted by low molecular PEO show a concentration dependence d∝c^{a/2} and G_{N}^{0}∝c^{1+a} with an exponent a close to 4/3. This result allows the clear discrimination between different theoretical models that predict 4/3 or other values between 1 and 2 and provides an important ingredient to tube model theories.

All-DNA System Close to the Percolation Threshold

We characterize via small-angle neutron scattering the structural properties of a mixture of all-DNA particles with functionalities 4 (A) and 2 (B) constrained by design to reside close to the percolation threshold. DNA base sequences are selected such that A particles can only bind with B ones and that at the studied temperature (10 °C) all AB bonds are formed and long-lived, originating highly polydisperse persistent equilibrium clusters. The concentration dependence of the scattered intensity and its wavevector dependence is exploited to determine the fractal dimension and the size distribution of the clusters, which are found to be consistent with the critical exponents of the 3-D percolation universality class. The value of DNA nanoparticles as nanometric patchy colloids with well-defined functionality, bonding selectivity, and exquisite control of the interaction strength is demonstrated.

Polymer Chain Conformation and Dynamical Confinement in a Model One-Component Nanocomposite

We report a neutron-scattering investigation on the structure and dynamics of a single-component nanocomposite based on SiO_{2} particles that were grafted with polyisoprene chains at the entanglement limit. By skillful labeling, we access both the monomer density in the corona as well as the conformation of the grafted chains. While the corona profile follows a r^{-1} power law, the conformation of a grafted chain is identical to that of a chain in a reference melt, implying a high mutual penetration of the coronas from different particles. The brush crowding leads to topological confinement of the chain dynamics: (i) At local scales, the segmental dynamics is unchanged compared to the reference melt, while (ii) at the scale of the chain, the dynamics appears to be slowed down; (iii) by performing a mode analysis in terms of end-fixed Rouse chains, the slower dynamics is tracked to topological confinement within the cone spanned by the adjacent grafts; (iv) by adding 50% matrix chains, the topological confinement sensed by the grafted chain is lifted partially and the apparent chain motion is accelerated. We observe a crossover from pure Rouse motion at short times to topological confined motion beyond the time when the segmental mean squared displacement has reached the distance to the next graft.

The role of the binding salt sodium salicylate in semidilute ionic cetylpyridinium chloride micellar solutions: a rheological and scattering study

The viscosity varies as a consequence of binding, first, and screening, later, action of the penetrating salt.

The value of transthoracic and transesophageal echocardiography for the diagnosis of the native aortic infective endocarditis valve complications: a case report and literature review

Despite its current limitations transthoracic echocardiography is still widely used for the anatomical and functional evaluation of patients with infective endocarditis. However, all these limitations can be overcome by using transesophageal echocardiography. We present the case of a 42-year-old male patient, diagnosed with aortic valve infective endocarditis, whose transthoracic echocardiography showed only a cusp vegetation and aortic regurgitation, but raised the suspicion of periannular complications. The transesophageal echocardiography revealed a circular aortic root abscess and a ventricular septal defect with left-to-right shunt, and consequently leads to a complete different surgical tactical approach. The patient was urgently referred for surgery due to the rapid deterioration of the hemodynamic status, and had a good outcome on the short-term follow-up.

A Combined SAXS/SANS Study for the in Situ Characterization of Ligand Shells on Small Nanoparticles: The Case of ZnO

ZnO nanoparticles (NPs) have great potential for their use in, e.g., thin film solar cells due to their electro-optical properties adjustable on the nanoscale. Therefore, the production of well-defined NPs is of major interest. For a targeted production process, the knowledge of the stabilization layer of the NPs during and after their formation is of particular importance. For the study of the stabilizer layer of ZnO NPs prepared in a wet chemical synthesis from zinc acetate, only ex situ studies have been performed so far. An acetate layer bound to the surface of the dried NPs was found; however, an in situ study which addresses the stabilizing layer surrounding the NPs in a native dispersion was missing. By the combination of small angle scattering with neutrons and X-rays (SANS and SAXS) for the same sample, we are now able to observe the acetate shell in situ for the first time. In addition, the changes of this shell could be followed during the ripening process for different temperatures. With increasing size of the ZnO core (d(core)) the surrounding shell (d(shell)) becomes larger, and the acetate concentration within the shell is reduced. For all samples, the shell thickness was found to be larger than the maximum extension of an acetate molecule with acetate concentrations within the shell below 50 vol %. Thus, there is not a monolayer of acetate molecules that covers the NPs but rather a swollen shell of acetate ions. This shell is assumed to hinder the growth of the NPs to larger macrostructures. In addition, we found that the partition coefficient μ between acetate in the shell surrounding the NPs and the total amount of acetate in the solution is about 10% which is in good agreement with ex situ data determined by thermogravimetric analysis.

Left renal cyst - left duplex kidney with compromised superior renal unit and ectopic ureteral orifice in the prostatic urethra

The urinary abnormalities are an important health problem. If they are not recognized in due time, they usually lead to the loss of the renal unit function. In many cases, the diagnosis is late and incidental.

CASE PRESENTATION

We present the case of M.I., a 74-year-old male admitted in our surgical unit with diffuse left lumbar pain, low urinary tract symptoms and slow increase in abdomen volume in the past 4 years. Computer tomography scan and ecography showed a large left lumbar cyst like mass with a dilated supernumerary ureter with ectopic ureteral orifice in the prostatic urethra and apparently normal anatomic inferior renal unit. The goal was the excision of the "cyst like" mass (superior left renal unit) but because of the anatomical particularities (extensive fibrosis and local topographical changes) total nephrectomy was performed.

CONCLUSIONS

Given a normal contralateral kidney, the discovery of a urinary abnormality can be a real challenge, their evolution being a silent one. This type of disease can be suspected only with the development of clinical symptoms. The anatomic particularities (duplex kidney) together with the long evolution of the disease changed the local topography making the preservation of the inferior left renal unit a difficult, almost impossible task for the surgeon.

Microscopic dynamics of polyethylene glycol chains interacting with silica nanoparticles

We present high resolution neutron spectroscopic investigations of polyethylene glycol matrices interacting attractively with neat SiO2 nanoparticles. We observe a very rich dynamical picture that significantly contradicts earlier conclusions on such systems. Investigating a short chain matrix we realized that a fraction of chains is attached at the nanoparticle surface suppressing completely its translational diffusion. Nevertheless these attached chains undergo an unchanged segmental dynamics seemingly forming a micellelike corona of chains attached with their OH end groups. Changing to methyl-terminated chains the picture changes drastically, now showing a tightly adsorbed layer that however is not glassy as often assumed but undergoes fast picosecond local dynamics. With the singular importance of end groups, mean field approaches are not applicable and future simulations should be redirected to model such unexpected phenomena.

Effect of nanoconfinement on polymer dynamics: surface layers and interphases

We present neutron spin echo experiments that address the much debated topic of dynamic phenomena in polymer melts that are induced by interacting with a confining surface. We find an anchored surface layer that internally is highly mobile and not glassy as heavily promoted in the literature. The polymer dynamics in confinement is, rather, determined by two phases, one fully equal to the bulk polymer and another that is partly anchored at the surface. By strong topological interaction, this phase confines further chains with no direct contact to the surface. These form the often invoked interphase, where the full chain relaxation is impeded through the interaction with the anchored chains.

Experimental determination of resolution function parameters from small-angle neutron scattering data of a colloidal SiO2dispersion

A dilute dispersion of charge-stabilized, monodisperse silica nanoparticles has been used to determine the instrumental resolution function parameters of a conventional small-angle neutron scattering instrument in pinhole geometry over the entire accessible range of momentum transferq. Independent determination of the structure parameters of the colloidal silica dispersion by small-angle X-ray scattering enables refinement of both theq-independent geometric and theq-dependent (wavelength spread or polychromaticity of the neutron beam) contributions to the resolution function. The procedure described is appropriate if no further instrumental characterization is available. It is demonstrated that the sample used for refining the resolution function parameters has to exhibit sharp structural scattering features such as Bragg reflections, form factor maxima and minima, or an inter-particle correlation peak for each instrumental configuration at which the measurements have been performed to cover aqrange of two orders of magnitude (0.03 <q< 3.2 nm−1).

Direct observation of confined single chain dynamics by neutron scattering

Neutron spin echo has revealed the single chain dynamic structure factor of entangled polymer chains confined in cylindrical nanopores with chain dimensions either much larger or smaller than the lateral pore sizes. In both situations, a slowing down of the dynamics with respect to the bulk behavior is only observed at intermediate times. The results at long times provide a direct microscopic measurement of the entanglement distance under confinement. They constitute the first experimental microscopic evidence of the dilution of the total entanglement density in a polymer melt under strong confinement, a phenomenon that so far was hypothesized on the basis of various macroscopic observations.

Aspherical refractive lenses for small-angle neutron scattering

Aspherical neutron lenses are discussed in detail as focusing elements for existing small-angle neutron scattering (SANS) diffractometers. The conceptual design can be obtained by analytical equations, while computer simulations provide the intensity distribution of the primary beam, which is strongly correlated with the instrumental resolution and the minimal momentum transferQ. For large illuminated sample/lens areas of 50 mm diameter the aspherical lens design is essential, while spherical lenses are limited toca20 mm diameter with a 60% spherical aberration for standard SANS experiments. Scattering experiments on different samples proved the applicability and revealed the resolution limits of the two lens types. From theoretical considerations it is proposed that lens cooling can be used to reduce the thermal diffuse scattering.

Anin situstudy of the t-butyllithium initiated polymerization of butadiene in d-heptane via small angle neutron scattering and H1-NMR

We present a combined 1H-NMR and small angle neutron scattering in situ study of the anionic polymerization of butadiene using t-butyllithium as the initiator. Both initiation and propagation phases were explored. This combined approach allows the structural and kinetic characteristics to be accessed and cross compared. The use of the D22 instrument (ILL Grenoble) permits the attainment of Q approximately equal to 2 x 10(-3) A. This, in turn, led to the identification of coexisting large-scale and smaller aggregates during all stages of the polymerization. The smaller aggregates contain most of the reacted monomers. Their structure changes from high functionality wormlike chains at early stages of the reaction to starlike aggregates where the crossover occurs at a degree of polymerization of approximately equal to 40. The initiation event involved these small, high functionality (approximately equal to 120) aggregates that apparently consisted of cross-associated t-butyllithium with the newly formed allylic-lithium head groups. As the initiation event progressed the initiation rate increased while the functionality of these small aggregates decreased and their size increased. Propagation, in the absence of initiation, was found to have a rate constant that was molecular weight dependent. At approximately 11 kg/mol the measured polymerization rate was found to increase while no further structural changes were seen.

Co-crystallization of poly(ethylene–butene) copolymers and paraffin molecules in decane studied with small-angle neutron scattering

PEB-nsemicrystalline poly(ethylene–butene) random copolymers may become important in industrial applications because of their capability to modify the paraffin crystals and to improve the viscoelastic properties of crude oil and refined fuel. The copolymer–paraffin interaction is rather complex and is not yet understood. Therefore, these polymers may also be of much interest in basic research. Systematic small-angle neutron scattering investigations of different polymer–paraffin systems have shown that PEB-ncopolymers are selective in their paraffin-modification capacity, depending on the crystalline degree which is tuned by the number `n' of ethyl side branches/100 backbone C atoms. Two mechanisms of polymer–paraffin interaction have been identified: on the one hand, co-crystallization of the paraffin and copolymer within thin platelets occurs as a consequence of a good fit between the self-assembling properties of the investigated polymer/paraffin pairs (PEB-7.5/C36and PEB-11/C24); on the other hand, primordial polymer aggregates act as a template for a subsequent paraffin crystallization when the polymer has a higher self-assembling point (PEB-7.5/C24) than the paraffin. Both mechanisms were found for the PEB-7.5/C30mixture.

Accidental Exposure to Blood and Biological Products in a Tertiary Teaching Hospital in Romania

Disclosure of the announcement rate of occupational exposure to blood and other biological fluids and the compliance rate for post exposure prophylaxis and monitoring measures among employees of the Regional Institute of Gastroenterology-Hepatology �Prof. Dr. Octavian Fodor� Cluj-Napoca. A prospective study was conducted between 2011-2016. All the hospital employees were included in the study. Descriptive analysis of reported cases of exposure to biological products was performed. Considering the number of employees and professional categories throughout the years of study, there was reported a very small number of accidents due to biological sample exposure, compared to statistical data. We have assessed the compliance of the exposed medical staff to post-exposure monitoring protocol, which was very low.

Characterization of autonomous thyroid adenoma: metabolism, gene expression, and pathology

Fifty-one in vivo characterized autonomous single adenomas have been studied for functional parameters in vitro, for gene and protein expression and for pathology, and have been systematically compared to the corresponding extratumoral quiescent tissue. The adenomas were characterized by a high level of iodide trapping that corresponds to a high level of Na+ /iodide symporter gene expression, a high thyroperoxidase mRNA and protein content, and a low H2O2 generation. This explains the iodide metabolism characteristics demonstrated before, ie, the main cause of the "hot" character of the adenomas is their increased iodide transport. The adenomas spontaneously secreted higher amounts of thyroid hormone than the quiescent tissue and in agreement with previous in vivo data, this secretion could be further enhanced by thyrotropin (TSH). Inositol uptake was also increased but there was no spontaneous increase of the generation of inositol phosphates and this metabolism could be further activated by TSH. These positive responses to TSH are in agreement with the properties of TSH-stimulated thyroid cells in vitro and in vivo. They are compatible with the characteristics of mutated TSH receptors whose constitutive activation accounts for the majority of autonomous thyroid adenomas in Europe. The number of cycling cells, as evaluated by MIB-1 immunolabeling was low but increased in comparison with the corresponding quiescent tissue or normal tissue. The cycling cells are observed mainly at the periphery; there was very little apoptosis. Both findings account for the slow growth of these established adenomas. On the other hand, by thyroperoxidase immunohistochemistry, the whole lesion appeared hyperfunctional, which demonstrates a dissociation of mitogenic and functional stimulations. Thyroglobulin, TSH receptor, and E-cadherin mRNA accumulations were not modified in a consistent way, which confirms the near-constitutive expression of the corresponding genes in normal differentiated tissue. On the contrary, early immediate genes expressions (c-myc, NGF1B, egr 1, genes of the fos and jun families) were decreased. This may be explained by the proliferative heterogeneity of the lesion and the previously described short, biphasic expression of these genes when induced by mitogenic agents. All the characteristics of the autonomous adenomas can therefore be explained by the effect of the known activating mutations of genes coding for proteins of the TSH cyclic adenosine monophosphate (cAMP) cascade, all cells being functionally activated while only those at the periphery multiply. The reason of this heterogeneity is unknown.

Spin accumulation and domain wall magnetoresistance in 35 nm Co wires

An enhancement of the resistance due to the presence of only one or two isolated domain walls is clearly evidenced by transport measurements in 35 nm epitaxial Co wires, 20 &mgr;m long. The deduced relative change in the resistivity is at least 1 order of magnitude larger than the one predicted from a model based on the mixing of spin channels occurring over the length scale of the domain wall width [P. M. Levy and S. Zhang, Phys. Rev. Lett. 79, 5110 (1997)]. This inconsistency can be resolved by taking the effect of spin accumulation into account, which scales in the case of Co over the much larger distance of the spin diffusion length.