Substitution of a hydroxamic acid anchor into the MK-2 dye for enhanced photovoltaic performance and water stability in a DSSC.

An efficient synthetic protocol to functionalize the cyanoacrylic acid anchoring group of commercially available MK-2 dye with a highly water-stable hydroxamate anchoring group is described. Extensive characterization of this hydroxamate-modified dye (MK-2HA) reveals that the modification does not affect its favorable optoelectronic properties. Dye-sensitized solar cells (DSSCs) prepared with the MK-2HA dye attain improved efficiency (6.9%), relative to analogously prepared devices with commercial MK-2 and N719 dyes. The hydroxamate anchoring group also contributes to significantly increased water stability, with a decrease in the rate constant for dye desorption of MK-2HA relative to MK-2 in the presence of water by as much as 37.5%. In addition, the hydroxamate-anchored dye undergoes essentially no loss in DSSC efficiency and the external quantum efficiency improves when up to 20% water is purposefully added to the electrolyte. In contrast, devices prepared with the commercial dye suffer a 50% decline in efficiency under identical conditions, with a concomitant decrease in external quantum efficiency. Collectively, our results indicate that covalent functionalization of organic dyes with hydroxamate anchoring groups is a simple and efficient approach to improving the water stability of the dye-semiconductor interface and overall device durability.

Meningitis caused by Abiotrophia defectiva: case report and literature review.

The genus Abiotrophia comprises fastidious Gram-positive bacteria previously classified as nutritionally variant streptococci (NVS). The isolation of NVS from the central nervous system (CNS) is very rare. We describe a case of meningitis due to Abiotrophia defectiva in a patient who underwent a total hip arthroplasty 4 days previously. It is possible that the organism could be introduced through the spinal anesthesia. We also review all cases of CNS infections caused by NVS.

[Rapidly progressive myonecrosis by Aeromonas veronii biotype sobria]. / Mionecrosis rápidamente progresiva por Aeromonas veronii biotipo sobria.

Myonecrosis due to Aeromonas spp is exceptional. We report the case of a diabetic patient with liver cirrhosis who developed a rapidly progressive myonecrosis by Aeromonas veronii biotype sobria. The portal of entry was an injury after falling down in an irrigation canal. The outcome was not favourable and surgical amputation of left leg was performed in spite of antibiotic treatment with cefotaxime and tobramicin. Aeromonas spp can be very aggressive and this microorganism should be considered in the differential diagnosis of skin and soft tissue infections with myonecrosis, specially after posttraumatic wound infections with a history of freshwater exposure.

Simple model for ac ionic conduction in solids.

We present a model for the ac conduction in ionically conducting solids that takes into account, in a simple way, the interaction between carriers. The Coulomb force forms an "ionic atmosphere" that exerts a restoring force on a central ion, whose motion corresponds to an overdamped oscillator. We consider the effect of the relaxation of the ionic atmosphere by introducing an additional equation for the displacement of the potential toward the particle position. The general behavior of the ac conductivity can be understood in terms of two types of motions: motion of the bound ion at high frequencies determined by microscopic friction, and a much slower motion coupled to the surrounding carriers relaxation at low frequencies.

Experimental evidence of a UV light-induced long-range electric field in nanostructured TiO2 thin films in contact with aqueous electrolytes.

Nanostructured TiO(2) thin-film electrodes of controlled thickness were obtained by immobilization of TiO(2) powder (Degussa P25) on SnO(2):F (FTO)-coated glasses by electrophoresis. The photocurrent-potential characteristics of the electrodes in contact with an indifferent aqueous electrolyte, for both front--and backside UV illumination, show the existence of a macroscopic electric field in the electrode region near the FTO substrate. This electric field, which is only photoinduced in the presence of water (it does not appear in TiO(2) dye-sensitized solar cells under visible illumination), apparently disappears when an efficient hole scavenger, like methanol, is added to the aqueous electrolyte. It is attributed to a nonhomogeneous spatial accumulation of photogenerated holes at surface-bound OH radicals resulting from the photooxidation of chemisorbed water molecules. The influence of film thickness and UV illumination mode (front- and backside) on the photoinduced electric field is analyzed by solving the transport equations for diffusion and drift of electrons.

[Incidence and risk factors for hepatitis A in the province of Guadalajara (Spain)]. / Incidencia y factores de riesgo de hepatitis A en la provincia de Guadalajara.

BACKGROUND: The decrease in the prevalence of hepatitis A in Spain may modify the characteristics of this infection because of the rise in the susceptible adult population. The aim of this study was to determine the incidence of this disease, as well as the epidemiological characteristics and the complications of patients diagnosed in the province of Guadalajara between 1991 and 1999. PATIENTS AND METHODS: The inclusion criterion was the presence of specific IgM together with an increase in alanine aminotransferase concentrations and/or symptoms compatible with acute hepatitis. RESULTS: The mean incidence was 7.13 cases/105 inhabitants. Considerable differences were found between years due to the presence of an outbreak. Most cases occurred in children and young adults. The most frequent risk factor found overall was contact with an infected individual but the distribution of risk factors differed between children and adults. CONCLUSIONS: The decrease in the prevalence of hepatitis A in Spain entails an increase in the susceptible adult population. Consequently, hepatitis A may cease to be a typically pediatric disease and may become one that also affects young adults in whom it may have different characteristics. This consideration should be borne in mind when designing a vaccination strategy.

[The prevalence of hepatitis A in the Guadalajara province. Is Spain a country with low endemia?]. / Prevalencia de hepatitis A en la provincia de Guadalajara. Es España un país de baja endemia?

BACKGROUND: Spain, together with the other southern European countries, was considered to be an area with a moderate degree of endemia. This fact has consequences for tourists that visit these areas and for vaccination strategies. A prevalence study was proposed in order to get to know the situation of this infection in the Guadalajara province. METHODS: 284 specimens of serum were taken from patients who were classified according to their age, sex and place of residence (with more or less than 10.000 inhabitants). In these specimens the presence of hepatitis A antibodies were studied, using a Microparticule Enzyme Immunoassay (MEIA) (Abbott). RESULTS: An increase in the prevalence was observed in older people, there is a low prevalence population (80%) in adults aged between 30 and 74 years. No differences were observed related to sex. In the stratified analysis according to age, differences were observed between the groups from rural and urban origins. CONCLUSIONS: The low prevalence of hepatitis A was found among the younger population, as seen in other studies carried out on a national level, and this together with a decrease in the frequency, means that Spain is included among the countries with low endemia. This fact has consequences for tourists who visit our country and for vaccination strategies, due to the increase in the number of adults who are susceptible to the infection.

[Urinary infection caused by non typhi Salmonella]. / Infección urinaria por Salmonella no typhi.

BACKGROUND: The aim of this study was to know the frequency and the clinical characteristics of urinary infection by non typhi Salmonella in our area in Spain. PATIENTS AND METHODS: The clinical histories of patients with urinary infection by non typhi Salmonella diagnosed in the Hospital General del Guadalajara from January 1990 to July 1999 were reviewed. RESULTS: During the period studied nine patients with urinary infection by non typhi Salmonella were diagnosed, representing 0.056% of the urinary infection diagnosed in our hospital over the same period. All the patients presented underlying disease and five were undergoing immunosuppressor treatment. Four patients presented urological disease. The most frequent serogroup was Salmonella enteritidis (7 cases). All the episodes were symptomatic. The same microorganism was isolated in stools in four patients. The evolution was favorable in five of the nine cases. Recurrence was observed in two patients and secondary bacteremia in one. Six patients required antibiotic treatment over two or more weeks. The mean length of treatment was of 2.5 weeks. CONCLUSIONS: Urinary infection by non typhi Salmonella is predominantly observed in patients undergoing immunosuppression or with urological disease. Prolonged antibiotic treatment is recommended due to its bad evolution.

Human infection with Hymenolepis diminuta: case report from Spain.

We report a case of Hymenolepis diminuta infection in a human. The patient was a 5-year-old girl referred to us through the onset of a cyanotic attack. Treatment with a single dose (10 mg/kg of body weight) of praziquantel was ineffective, but the parasite was eradicated after three treatment cycles with the same drug at dosages of 25 mg/kg/day for 5 days.

[Microbiologic diagnosis of typhoid fever: report on an outbreak]. / Diagnóstico microbiológico de la fiebre tifoidea: a propósito de un brote.

BACKGROUND: The incidence of typhoid fever has greatly fallen in Spain although sporadic cases and limited outbreaks may be observed. The usefulness of the serum agglutinin studies for the diagnosis of this disease has been questioned by many authors. However, this diagnosis criteria continues to be used in Spain. The usefulness of blood cultures, stool cultures, urinecultures and serological test is herewith compared. METHODS: Three groups were prospectively studied: 18 patients with typhoid fever from one single outbreak, 50 blood donors, and 24 patients with other infections. Blood, stool culture, urinecultures and serology (agglutination) were carried out in the first group and in the other two groups serological test were used to determine the cut-off points and study cross reactions. RESULTS: Blood culture was found to be the most sensitive technique (94%) followed by stool culture (53%). No positive urineculture of seroconvesrion were observed. The cut off points accepted following the study of the donors were 1/160 or greater for the O antigen and 1/320 or greater for the H antigen. Two false positive for the O antigen and 3 for the H antigen were observed in the 24 patients with other infections. CONCLUSIONS: When suspecting typhoid fever, the combined use of blood culture and stool culture is recommended. The usefulness of serological test in our area lays in the observation of seroconversion associated to a compatible clinical picture. Its performance should not being considered as adequate in unspecific febrile syndromes.