Elimination of Interface Energy Barriers Using Dendrimer Polyelectrolytes with Fractal Geometry.

In this work we study conjugated polyelectrolyte (CPE) films based on polyamidoamine (PAMAM) dendrimers of generations G1 and G3. These fractal macromolecules are compared to branched polyethylenimine (b-PEI) polymer using methanol as the solvent. All of these materials present a high density of amino groups, which protonated by methoxide counter-anions create strong dipolar interfaces. The vacuum level shift associated to these films on n-type silicon was 0.93 eV for b-PEI, 0.72 eV for PAMAM G1 and 1.07 eV for PAMAM G3. These surface potentials were enough to overcome Fermi level pinning, which is a typical limitation of aluminium contacts on n-type silicon. A specific contact resistance as low as 20 mΩ·cm2 was achieved with PAMAM G3, in agreement with the higher surface potential of this material. Good electron transport properties were also obtained for the other materials. Proof-of-concept silicon solar cells combining vanadium oxide as a hole-selective contact with these new electron transport layers have been fabricated and compared. The solar cell with PAMAM G3 surpassed 15% conversion efficiency with an overall increase of all the photovoltaic parameters. The performance of these devices correlates with compositional and nanostructural studies of the different CPE films. Particularly, a figure-of-merit (Vσ) for CPE films that considers the number of protonated amino groups per macromolecule has been introduced. The fractal geometry of dendrimers leads to a geometric increase in the number of amino groups per generation. Thus, investigation of dendrimer macromolecules seems a very good strategy to design CPE films with enhanced charge-carrier selectivity.

Effects of Deposition Temperature and Working Pressure on the Thermal and Nanomechanical Performances of Stoichiometric Cu3N: An Adaptable Material for Photovoltaic Applications.

The pursuit of efficient, profitable, and ecofriendly materials has defined solar cell research from its inception to today. Some materials, such as copper nitride (Cu3N), show great promise for promoting sustainable solar technologies. This study employed reactive radio-frequency magnetron sputtering using a pure nitrogen environment to fabricate quality Cu3N thin films to evaluate how both temperature and gas working pressure affect their solar absorption capabilities. Several characterization techniques, including X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), Raman spectroscopy, scanning electron microscopy (SEM), nanoindentation, and photothermal deflection spectroscopy (PDS), were used to determine the main properties of the thin films. The results indicated that, at room temperature, it is possible to obtain a material that is close to stoichiometric Cu3N material (Cu/N ratio ≈ 3) with (100) preferred orientation, which was lost as the substrate temperature increases, demonstrating a clear influence of this parameter on the film structure attributed to nitrogen re-emission at higher temperatures. Raman microscopy confirmed the formation of Cu-N bonds within the 628-637 cm-1 range. In addition, the temperature and the working pressure significantly also influence the film hardness and the grain size, affecting the elastic modulus. Finally, the optical properties revealed suitable properties at lower temperatures, including bandgap values, refractive index, and Urbach energy. These findings underscore the potential of Cu3N thin films in solar energy due to their advantageous properties and resilience against defects. This research paves the way for future advancements in efficient and sustainable solar technologies.

[Progressive multifocal leukoencephalopathy associated with human immunodeficiency virus infection: the clinical, neuroimaging, virological and evolutive characteristics in 35 patients]. / Leucoencefalopatía multifocal progresiva asociada a la infección por el virus de la inmunodeficiencia humana: características clínicas, de neuroimagen, virológicas y evolutivas de 35 pacientes.

BACKGROUND: The clinical, neuroimaging, virologic and evolutive characteristics of progressive multifocal leukoencephalopathy (PML) in 35 AIDS patients are studied. PATIENTS AND METHODS: PML was diagnosed by clinical and neuroimaging criteria in 32 patients and by autopsy in other three. The detection of JC virus (JCV) was done by PCR and further hybridization of the amplified DNA in peripheral blood lymphocytes, urine and CSF. RESULTS: 127 of 930 HIV positive patients were admitted by neuropsychiatric symptoms and of them 35 (SD 27.6%) by PML. The PML patients had a mean CD4 lymphocytes count of 75.3 (82.0)/x 10(6)/l and a HIV viral load of 330,698 (538,971) copies of RNA/ml. Thirty patients did not receive any anti-retroviral therapy or only transcriptase inhibitors monotherapy and five triple anti-retroviral therapy, including a proteases inhibitor. Multiple hypodense lesions on CT (53.1%) and T2 hyperintense lesions on MRI (58.3%) were the most frequent neuroimaging findings. JCV was detected in 20/21 (95.2%) LMP patients: 18/19 detections in lymphocytes, 6/8 in CSF and 4/6 in urine. The mean survival without and with antiretroviral therapy were 3.0 (0.47) and 21.4 (4.4) months (p < 0.001) in 34 patients followed. PML progressed to death in 31/34 patients (91.2%), and remained stable in 3/34 (8.8%). A patient was lost for follow-up. CONCLUSIONS: The application of clinical and neuroimaging criteria and the detection of JCV in CSF are useful for high presumption diagnosis of PML without brain biopsies. JCV detection in lymphocytes and in urine have a much lower predictive value. The evolution and survival of this disease can improve with triple anti-retroviral therapy including a protease inhibitor.

[The clinical significance of culturing Toxoplasma gondii on blood and other organic media]. / Significado clínico del cultivo de Toxoplasma gondii en sangre y en otros medios orgánicos.

BACKGROUND: The aim of this study was to determine the value of the Toxoplasma gondii culture in blood and in other organic fluids in HIV positive and negative patients. METHODS: Retrospective analysis (October 1990-May 1992) was carried out including all patients with positive cultures for T. gondii admitted to the Hospital Central of Asturias. The parasite was identified by monoclonal antibodies against the tachyzoite membrane. All patients with positive cultures were treated with pyrimethamine and sulphadiazine. RESULTS: Three hundred two samples from 256 patients, seropositive and seronegative for HIV, were analyzed. Of the seropositive group 8/45 (18%) had positive cultures for T. gondii versus 9/211 (4.3%) of the seronegative group (p = 0.002). Of the 19 positive samples, 15 were from blood, 3 from bronchoalveolar lavage and one from the vitreous fluid. Four out of 9 patients (44%) with AIDS and encephalic toxoplasmosis (ET) had blood cultures positive for T. gondii. Another 4 patients with AIDS presented toxoplasmenia without visceral involvement. Of the 9 HIV seronegative patients (3 immunodepressed patients), 4 had pulmonary toxoplasmosis, one ocular toxoplasmosis, and other clinical forms of toxoplasmosis were seen in the remaining 4. All the patients evolved to cure except 2 cases coinfected by cytomegalovirus who died. CONCLUSIONS: The identification of Toxoplasma gondii may be performed by blood cultures in half of the patients with AIDS and encephalic toxoplasmosis and in an undetermined percentage of the other clinical forms both in immunocompetent and immunodepressed subjects. In addition, toxoplasmemia has been registered in AIDS patients preceding any other organic seating of the parasite. Early antitoxoplasma therapy may, therefore, be effective.

Meropenem monotherapy is as effective as and safer than imipenem to treat brain abscesses.

The efficacy of carbapenems versus cefotaxime (8g/day)+metronidazole (1.5-2g/day) [combined standard chemotherapy (CSC)] for the treatment of brain abscess was compared. Fifty-nine adult patients with brain abscesses received either imipenem or meropenem (3-4g/day) or CSC for a mean of 5 weeks, in addition to neurosurgery in most cases. Cure was obtained in 84.7% of cases; 42/47 (89.4%) on carbapenems [18/22 (81.8%) on imipenem versus 24/25 (96.0%) on meropenem] and 8/12 (66.7%) on CSC (P=0.06). Seven patients with multiple abscesses were treated with imipenem (1 died; cure rate 85.7%), five with meropenem (all survived; cure rate 100%) and five with CSC (2 died; cure rate 60%) (P<0.4). Neurosurgery was performed in 43/59 cases (72.9%); 17 (77.3%) in the imipenem group, 21 (84.0%) in the meropenem group and 5 (41.7%) in the CSC group (P=0.02). There was no significant difference in the rate of relapse requiring re-intervention. Treatment with meropenem was associated with a lower mortality than CSC (P=0.026). Seizures were observed only with carbapenems [8/22 (36.4%) for imipenem versus 2/25 (8.0%) for meropenem; P=0.03]. Carbapenems were more effective than CSC for treatment of brain abscesses. Because meropenem induced significantly fewer seizures than imipenem with at least the same clinical efficacy, the former appears to be a better choice to treat this infection.

Successful intrathecal ethanol block for intractable spasticity of AIDS-related progressive multifocal leukoencephalopathy.

OBJECTIVE: To study the efficacy of intrathecal ethanol block to relieve intractable spasticity in AIDS-related progressive multifocal leukoencephalopathy (PML) when long-term intrathecal baclofen infusion cannot be used. METHODS: A 33-year-old man with AIDS-related PML developed very severe spastic paraparesis (Ashworth rigidity score, 4) and painful muscle spasms. The patient was unable to sit in his wheelchair and remained bed bound. Combined oral baclofen and tizanidine at therapeutical doses were used without any effect on the spasticity. The patient refused the placement of an intrathecal catheter for long-term baclofen infusion. A single intrathecal ethanol (6 ml) injection in the L2-L3 intervertebral space with the patient placed in a lateral Trendelenburg (40 C) position was performed. RESULTS: The procedure was very effective in improving the stiffness (Ashworth rigidity score. 2, after the technique) and the muscle spasms disappeared. No side effects during or after the injection were observed. CONCLUSION: Intrathecal ethanol block is a last but very useful choice for treatment of intractable spasticity in PML and other neurologic disorders in AIDS patients when other oral treatments have failed and intrathecal baclofen infusion is not suitable.

Eikenella corrodens brain abscess after repeated periodontal manipulations cured with imipenem and neurosurgery.

Eikenella corrodens is a facultatively anaerobic gram-negative rod that colonizes the oral cavity and very rarely produces central nervous system (CNS) infections. Frontal lobe abscesses are occasionally associated with a dental source of infection. We report a case of an adult man with overzealous dental cleaning habits who developed a right frontal brain abscess caused by E. corrodens. He underwent neurosurgical drainage of the pus and was successfully treated with imipenem 4 g/i.v./day for 4 weeks with no complications. Repeated periodontal trauma could explain the Eikenella brain abscess in this case.

[Pulmonary toxoplasmosis. Study of 4 cases and review of the literature]. / Toxoplasmosis pulmonar. Estudio de 4 casos y revisión de la literatura.

BACKGROUND: Description of four cases of pulmonary toxoplasmosis and review of the literature. METHODS: A retrospective analysis (October 1990-December 1992) was carried out of the patients with samples of tracheal aspirate, bronchoalveolar lavage (BAL) and lung biopsy positive for T. gondii by immunofluorescence with anti-P30 monoclonal antibodies and cell cultures. RESULTS: Four patients were diagnosed of pulmonary toxoplasmosis, three being immunosuppressed (one renal transplant, one with chronic lymphoid leukemia and one intravenous drug user HIV seronegative) and the remaining one healthy. All the patients developed progressive dyspnea and a radiologic pattern of interstitial pneumonitis (3) or alveolar condensation (1). Three of the patients were cured with pyrimethamine and sulphadiazine. One patient had coinfection by CMV and died. Another 52 cases of this rare condition have been reported in the literature. CONCLUSIONS: In the authors experience, bronchoalveolar lavage material and lung biopsy for T. gondii culture should be performed in immunosuppressed patients with an unclear interstitial radiologic pattern to rule out pulmonary toxoplasmosis.

[Epidemiologic study of Lyme disease in Asturias]. / Estudio epidemiológico de la enfermedad de Lyme en Asturias.

BACKGROUND: The aim of this study was to confirm the Sierra del Sueve (Asturias) as an endemic area for Lyme's disease and determine the seroprevalence of this disease in inhabitants of this and other zones of Asturias. METHODS: A taxonomic study of 233 ticks in this county was carried out and the rate of infection by Borrelia burgdorferi was determined by culture in modified Kelly medium. Seroprevalence of Lyme's disease was studied by enzyme-immunoanalysis IgG-IgM in 150 inhabitants from several counties of Asturias. RESULTS: The tick Ixodes ricinus is the most abundant species in the zone. All the cultures of Ixodes for Borrelia burgdorferi were negative. Among the farmers of the area of Sueve, seroprevalence of Lyme's disease was higher than in other population groups. CONCLUSIONS: The Sierra del Sueve is an endemic area of Lyme's disease because of the appropriate vector I. ricinus and the super-population of Fallow deer. In this county the percentage of asymptomatic seropositives for this disease is much higher than that of other zones in Spain.

Imipenem therapy of brain abscesses.

The efficacy of imipenem versus standard chemotherapy (both in addition to neurosurgery) in the treatment of brain abscess was compared in a retrospective study. Cure was obtained in 52 of 60 (86.7%) patients in the standard group, and in 15 of 15 (including 5 patients with multiple brain abscesses) in the imipenem group. Cure without neurosurgery was observed in 2 of 60 (3.3%) and 3 of 15 (20%) of the cases, respectively (p = 0.08). Levels of imipenem in blood, cerebrospinal fluid, and brain pus were above the minimum inhibitory concentrations of most of the abscess isolates. Side effects of imipenem were rare and tolerance was excellent. Imipenem monotherapy (3-4 g/day) for five weeks seems a reasonable therapeutic choice for treatment of bacterial brain abscesses.