A first-principles study of the atomic layer deposition of ZnO on carboxyl functionalized carbon nanotubes: the role of water molecules.

The formation of heterostructures that combine a large surface area with high surface activity has attracted the attention of the scientific community due to the unique properties and applications of these heterostructures. In this work, we describe - at the atomic level - the full reaction mechanisms involved in the atomic layer deposition of a hybrid ZnO/CNT inorganic structure. First, the pristine CNTs are chemically activated with a carboxylic acid, a process unique to carbon materials. Diethylzinc (DEZ) and water are used as gas-phase precursors to form ZnO. Our findings show that DEZ is physically adsorbed on the CNTs during the exposure of the first precursor. The ligand-exchange to generate chemisorbed ethyl zinc on the O side of the COOH group needs to overcome an energy barrier of 0.06 eV. This is a very small energy if compared to the values (0.5-0.6 eV) obtained in previous studies for OH functionalized surfaces. The height of the barrier is associated with the C[double bond, length as m-dash]O side, which mediates the H proton's exchange from the OH group to the C2H5 ligand. Furthermore, upon exposure to the oxidizing agent (H2O), ethyl zinc exchanges its last ligand as ethane, and it accepts a hydroxyl group through a self-limiting reaction with an energy barrier of 0.88 eV. Notice that the energy barrier of the second ligand-exchange is larger than of the first. We have also analyzed the effect in the saturation of the second precursor: as the quantity of water molecules increases, the long-range interactions tend to repel them. However, the energy barrier of the second ligand-exchange decreases from 1.53 eV to 0.88 eV for one and two water molecules, showing a clear dependence on the oxidizing agent. Non-covalent interactions are used as a tool to visualize the driving forces that take place during each partial reaction in real space. Our study points out the importance of using the right functionalization agent to achieve a controlled and conformal ALD growth at the initial steps of the formation of hybrid ZnO/CNT structures, as well as the role played by the oxidizing agent to lower the energy barrier on the second ALD step.

Understanding the first half-ALD cycle of the ZnO growth on hydroxyl functionalized carbon nanotubes.

We report the adsorption of diethylzinc on hydroxyl functionalized carbon nanotubes. This study intends to understand, at the atomic level, the initial stages of ZnO formation by atomic layer deposition. Our study begins with the molecule physisorbed on the nanotube (initial state of the reaction). The final state of this reaction is when the H atom of the hydroxyl group is abstracted and migrates to one ethyl group of diethylzinc. The oxygen atom relaxes towards the nanotube and forms a strong bond with a carbon atom, while the remaining part of the molecule forms a bond with the H atom and physisorbs on top of the ZnO unit. The probability for this process to happen is very high since the energy to desorb the diethylzinc molecule is higher than the energy needed to break down the O-H bond. Non-covalent interactions and charge density distributions are plotted to confirm the break-down, formation of bonds, and repulsion during the reaction pathway.

Third-order nonlinear optical properties of a multi-layer Al2O3/ZnO for nonlinear optical waveguides.

This is a report of a study of the nonlinear optical properties of samples based on multiple Al2O3/ZnO bilayers fabricated by atomic layer deposition (ALD) in silica. The multi-layer configuration for samples consists of alternated layers of constant thickness of Al2O3 (Δx) and ZnO (Δy) nanolaminates with a total thickness of ∼ 500 nm. The physical properties of the samples were characterized by means of TEM, spectrophotometry and variable angle spectroscopic ellipsometry. The absorptive and refractive contributions to the nonlinearity of the samples were studied by means of z-scan technique using a 100 fs at 800 nm. The nonlinear parameters, ß and n2, are studied using different values of the layers thickness, Δx and Δy, in the nanolaminated stack. The possible applications in optical signal processing system are discussed by means of the figures of merit W and T.

[Analysis of medication prescription in an Argentinian geriatric hospital]. / Análisis de la prescripción de medicamentos en una comunidad geriátrica Argentina.

BACKGROUND: Although polypharmacy may be justified in elderly patients with multiple diseases, it may be dangerous, especially when it includes potentially inappropriate medications (PIM). AIM: To identify inappropriate medication and factors associated with the most relevant prescriptions among older people. MATERIAL AND METHODS: Cross-sectional observational analysis of drugs prescribed during the first trimester of 2010 to 179 older adults aged 77 ± 8 years (98 women), living in a geriatric reference hospital in Argentina. The use of potentially inappropriate medications (PIM) in elderly patients was analyzed using Beers Criteria updated to 2012. RESULTS: The mean number of drugs prescribed per individual was 6.1 ± 2.7. The most commonly used drugs were anti-ulcer agents (58.1%), agents acting on the renin-angiotensin system (54.2%), antithrombotic medications (50.8%) and benzodiazepines (50.8 %). The use of antacids and anti-ulcer agents, psychotropic drugs and PIM was significantly higher among patients using six or more drugs daily, compared to the less medicated group (odds ratio (OR) = 6.8, 95% confidence intervals (CI) 3.5-13.2; OR=15.0, 95%CI 5.9-38.4; OR=5.0; 95%IC 2.6-9.8, respectively). Thirty one percent of participants using non-steroidal anti-inflammatory drugs, were not receiving medications for gastric protection. One to four drugs included in the Beers list were prescribed to 66% of participants. CONCLUSIONS: Despite the high prevalence of use of antacids and anti-ulcer agents, these drugs were not prescribed to a significant proportion of patients using non-steroidal anti-inflammatory drugs. Strategies to optimize pharmacotherapy in the elderly population are urgently required.

Atomic-scale study of TiO2-GR nanohybrid formation by ALD: the effect of the gas phase precursor.

In the present work, we report on a theoretical-computational study of the growth mechanism of the TiO2-Graphene nanohybrid by atomic layer deposition. Hydroxyl groups (OH) are anchoring sites for interacting with the main ALD titanium precursors (Tetrakis (dimethylamino) Titanium, Titanium Tetrachloride, and Titanium Isopropoxide). Results demonstrate that the chemical nature of the precursor directly affects the reaction mechanism in each ALD growth step. Tetrakis(dimethylamino)titanium is the precursor that presents a higher affinity (lower energy barriers for the reaction) to hydroxylated graphene in the growth process. A complete reaction mechanism for each precursor was proposed. The differences between precursors were discussed through the non-covalent interactions index. Finally, the water molecules help reduce the energy barriers and consequently favor the formation of the TiO2-graphene nanohybrid.

On the estimation of sugars concentrations using Raman spectroscopy and artificial neural networks.

In this paper, we present an analysis of the performance of Raman spectroscopy, combined with feed-forward neural networks (FFNN), for the estimation of concentration percentages of glucose, sucrose, and fructose in water solutions. Indeed, we analysed our method for the estimation of sucrose in three solid industrialized food products: donuts, cereal, and cookies. Concentrations were estimated in two ways: using a non-linear fitting system, and using a classifier. Our experiments showed that both the classifier and the fitting systems performed better than a Support Vector Machine (SVM), a Linear Discriminant Analysis (LDA), a Linear Regression (LR), and interval Partial Least Squares (iPLS). The best-case obtained by an FFNN for water solutions was 93.33% of classification and 3.51% of Root Mean Square Error in Prediction (RMSEP), compared with 82.22% obtained by a LDA. Our proposed method got an RMSEP of 1% for the best-case obtained with the food products.

Characterization of glycated hemoglobin based on Raman spectroscopy and artificial neural networks.

The World Health Organization has declared the glycated hemoglobin (HbA1c) as a gold standard biomarker for diabetes diagnosis; this has led to relevant research on the spectral behavior and characterization of HbA1c. This paper presents an analysis of Raman peaks of commercial lyophilized HbA1c, diluted in distilled water, using concentrations of 4.76% and 9.09%, as well as pure powder (100% concentration). Vibrational Raman peak positions of HbA1c powder were found at 1578, 1571, 1536, 1436, 1311, 1308, 1230, 1222, 1114, 1106, 969, 799 and 665 cm-1; these values are consistent with results reported in other works. Besides, a nonlinear regression model based on a Feed-Forward Neural Network (FFNN) was built to quantify percentages of HbA1c for unknown concentrations. Using the Raman spectra as independent variables, the regression provided a Root Mean Square Error in Cross-Validation (RMSECV) of 0.08% ±â€¯0.04. We also include a detailed molecular assignment of the average spectra of lyophilized powder of HbA1c.

Effect of a moderate electric field on the salting of Atlantic Salmon (Salmo salar): An experimental study and phenomenological understanding.

Salting is one of the oldest methods of preserving food. The main limitation of salting is its extended processing time due to slow salt diffusion. A moderate electric field (MEF) can improve the mass transfer rate through electroporation. Regularly, mass transfer processes are modeled with Fick's second law. However, due to the anisotropic nature of food microstructures, it might be more appropriate to use an anomalous model. The main objective of this study was to search for a phenomenological explanation for salt and water diffusion in the salmon brining process coupled with MEF. Salmon fillets were cut into finite cylinders (0.025 × 0.025 m) and brined in two salt concentrations (6 and 24% w/w NaCl) at 6 °C for 20 h. MEFs were applied in the range of 0 to 2 V/cm. The salt and water contents of the salmon were measured during the process. Fick's second law and anomalous model based on fractional calculus were used to describe the diffusion phenomena. The results showed that an MEF tended to reduce the brining processing time and increase the salt content of salmon. This effect is predominantly due to an increase in the equilibrium salt concentration in the salmon tissue. Mathematical analysis shows that the anomalous diffusion model is more suitable for representing the brining process, exhibiting superdiffusion behavior (α > 1). An MEF accelerates the salt mass transfer into salmon tissue even at lower temperatures, significantly reducing the processing time. In addition, the diffusion process can be characterized with an anomalous model.

Optimization of hot-air drying conditions for cassava flour for its application in gluten-free pasta formulation.

The design and development of gluten-free foods requires a comprehensive understanding of the behavior of the raw materials to attain the same cooking and nutritional quality as gluten-based food. The objective of this study was to determine the optimal hot-air drying conditions for elaboration of cassava flour to be used in a gluten-free pasta formulation. The results showed that the operational conditions to minimize the hot-air drying time (57 min) to produce cassava flour with higher water holding capacity was 57 ℃ at 3 m/s. Then, the optimal formulation for the pasta was found to be cassava (26 g/100 g), amaranth flour (12 g/100 g), and carboxymethyl cellulose (0.23 g/100 g), which maximized the Aw (0.160), moisture content (3.10 g/100 g), hardness (5.02 N), and protein content (9.30 g/100 g), and it is used for the sensorial analysis, which showed that an earthy taste was the main problem with consumer satisfaction.

[Gunshot bladder trauma: case report and literature review]. / Traumatismo vesical por arma de fuego: presentación de un caso y revisión de la literatura.

OBJECTIVE: To report one case of gunshot bladder trauma and to review its diagnosis and treatment in the related literature. METHODS: We report the case of a 43-year-old-male with an abdominal firearm wound and gross haematuria. Imaging diagnosis by abdominal and pelvic CT and CT-cystography. Surgical treatment. RESULTS: CT-cystography showed extraperitoneal bladder rupture. Exploratory laparotomy to evaluate for other associated injuries. Bladder wall surgical closure and ureteroneocystostomy with transvesical technique because of complete distal ureter tear. Broad spectrum antibiotherapy. Favourable progress. The patient was discharged at 14th day. CONCLUSIONS: Firearm bladder traumas are a rare entity. Surgical exploration and closure is mandatory. In haemodynamicaly stable patients, abdomen and pelvis CT and CT-cystography allow us to rule out associated injuries and to classify the bladder trauma type. Ureteral damage associated in 5-8,9%, diagnosed during surgical exploration. Broad-spectrum antibiotherapy in all patients.

[Thiamine retention as a function of thermal processing conditions: canned salmon]. / Retención de tiamina como función de las condiciones de proceso térmico en salmón en conserva.

The present work studied the effect of different treatments at high temperatures on the nutritional properties of thiamine retention and color measurement experimentally. Canned salmon (Salmo salar) was processed under different temperatures and time conditions (110 degrees C for 135 minutes; 114 degrees C for 89 minutes; 118 degrees C for 69 minutes and 121 degrees C for 62 minutes). Thiamine was determined by HPLC before and after the process. Color changes, due to processing conditions, were also measured utilizing a Hunter colorimeter. The canning was prepared in 300 x 407 cans and sterilized until Fo value reached 6 min. The nutritional value or index represented by the B1 vitamin or thiamine was affected by high temperature and time exposition. The lowest loss of thiamine of 19.2% was obtained in the canned salmon sterilized at 114 degrees C for 89 minutes. The color in canned salmon was different from the raw material, with a severe loss of red color and a greater clarity of the meat.

Counting of lymphocyte subpopulations using standard versus low-dose antiCD3 monoclonal antibody treatment.

The monoclonal anti-CD3 antibody is used as part of prophylaxis and also in treatment of rejection. In the present article we analyzed changes in different lymphocyte subpopulations after anti-CD3 treatment. T lymphocytes were decreased under anti-CD3 antibody administration, with a simultaneous increase in B lymphocytes but no changes in natural killer (NK)cells. No differences were found between patients administered anti-CD3 antibody (Ab) at 5 versus 2.5 mg/d. It is uncertain whether these changes may be implicated in the lack of response or in the prophylactic effects of anti-CD3 Ab.

[Malignant vesico-prostatic fibrous histiocytoma]. / Histiocitoma fibroso maligno vesicoprostático.

Among the adult bladder sarcomas it's extremely rare as an histological variety the malignant fibrous histiocytoma. We present a case of a 25 years old young male with bladder and prostate both affected, successfully treated with radical surgery and poliquimiotherapy. We also reviewed the bibliography about this neoplasias up to now.

[Giant retroperitoneal hemangiopericytoma]. / Hemangiopericitoma retroperitoneal gigante.

We present a new case of retroperitoneal hemangiopericytoma with the special feature of a big size tumour. Due to this feature and also to the hypervascularitation we proceeded a preoperative arterial embolization that made possible its complete removal. We did a bibliographic review showing the fundamental clinic pathologic and therapeutical basic aspects of this tumours.

[Penile fracture involving cavernous bodies and urethra]. / Fractura de pene con afectación de cuerpos cavernosos y uretra.

Reports on fracture of the penis are scarce in the spanish urological literature and in most cases injury appear limited to the corpora cavernosa. In this report a case of rupture of both corpora cavernosa and the urethra during sexual intercourse is presented. Early surgical treatment rendered good results. A literature review on currently recommended diagnostic and treatment practices is presented.

[Testicular torsion: which suture should be used?]. / Torsión testicular: qué sutura utilizar?

We report a case of left testicular torsion four months after a similar homolateral case in which we did detorsion and bilateral fixation of both testicles. The antecedent orchiopexy was accomplished using 3-0 silk and transseptal fixation of the contralateral testicle. A history of bilateral orchiopexy should nor interfere with diagnosing torsion in the acute scrotum. We recommend the use of nonabsorbable suture material joining the testis to the dartos muscle in 3 locations and the contralateral hemiscrotum must be explored.

Dietary calcium intake by a group of 13 18-year-old Costa Rican teenagers.

Calcium intake is one of the most important predictors of the amount of bone mass gained during growth. Therefore, this study was designed to estimate the dietary calcium intake of Costa Rican urban and rural adolescents ages 13-18 years old. Calcium dietary intake was determined using prospective 3-d diet records. Two-thirds (or 66.7%) or less of the Adequate Intake (AI) was used as the criterion for inadequate calcium intake as suggested by several authors. Reported mean daily calcium intake was 573 mg +/- 290. On average 82% of the adolescents did not meet two-thirds of the Al for calcium. A higher percentage of rural than urban youngsters reported inadequate calcium intake (92% and 75% respectively, p = 0.000). Likewise a higher percentage of girls (91%) than boys (77%) reported marginal calcium intake. This study shows evidence that nutritional interventions and educational strategies are urgent for increasing calcium consumption among adolescents in order to reduce the future burden of osteoporosis in old age.

[Effect of concentration temperature of kiwi fruit pulp on color, chlorophyll and ascorbic acid]. / Efecto de la temperatura de concentración de pulpa de kiwi sobre el color, clorofila y ácido ascórbico.

A study was established to evaluate concentration temperatures (25, 30, 35, 40 and 45 degrees C) on kiwi fruit pulp concentrated to 32 degrees Brix, with vacuum regulation. Munsell and sensorial colour, ascorbic acid and chlorophyll amount remanent were analyzed. Both, 25 and 30 degrees C concentration temperatures treatments, in the most of variables, experimented low deteriorate and differ with the other treatments. Ascorbic acid measurements had not significative differences (P < 0.95). Chlorophyll assays showed a decreased (70%) in the amount remanent over 35 degrees C in comparison to 25 degrees C treatments. 40 and 45 degrees C treatments showed traces of chlorophyll. Sensorial colour did not showed variations on 25 and 30 degrees C treatments; they were classified as bright green. Other treatments present colour deteriorate: 35 degrees C treatment was green-yellowish classified, and 45 degrees C treatments brown-greenish categories. Munsell colour showed the same relations, were increasing the concentration temperatures, decrease the green colour and increase the yellow colour.

Esteatosis hepatica aguda en el tercer trimestre de embarazo gemelar: reporte de caso / Acute hepatic esteatosis during third trimester twin pregnancy: case report

Introducción: La esteatosis hepática aguda del embarazo (EHAE) es una patología metabólica grave e infrecuente caracterizada por esteatosis hepática microvesicular que conduce a insuficiencia hepática aguda. Aparece generalmente en el tercer trimestre de gestación y se reconoce el embarazo gemelar como un factor de riesgo para su desarrollo. Presentación del caso: Paciente femenina de 25 años sin antecedentes médicos, 2 embarazos, 1 parto y 0 abortos, cursando embarazo gemelar de 31 semanas de gestación, consultó por presentar cuadro de dolor abdominal, vómitos e ictericia. Se sospechó hepatitis aguda y se decidió hospitalizar. Al ingreso una ecografía obstétrica precisó latidos fetales ausentes decidiéndose interrupción del embarazo de urgencia. La paciente evolucionó con síndrome confusional y epistaxis masiva requiriendo transfusión. Exámenes de ingreso evidenciaron insuficiencia renal, insuficiencia hepática y trombocitopenia. Ingresó a Unidad de Paciente Crítico con diagnóstico de síndrome de HELLP requiriendo soporte con ventilación mecánica. Persistió con mala evolución clínica por lo que se solicitó tomografía de abdomen y pelvis mostrando signos de pancreatitis aguda y hematoma subcapsular hepático. Exámenes de control objetivaron hiperbilirrubinemia, transaminasas elevadas, hipoalbuminemia, hipocolesterolemia y tiempo de protrombina elevado. Se planteó diagnóstico de esteatosis hepática aguda del embarazo. Ingresó a lista de espera para trasplante hepático. Posteriormente evolucionó con mejoría espontánea de la función hepática y se logró extubar tras dos semanas de hospitalización. Discusión: El desarrollo de esteatosis hepática aguda del embarazo es infrecuente y potencialmente grave debiéndose interrumpir el embarazo precozmente y manejarse en unidades de paciente crítico debido a su alta mortalidad.

Introduction: Acute hepatic esteatosis of pregnancy (AHEP) is a serious and uncommon metabolic pathology characterized by microvesicular liver steatosis leading to acute liver failure. It usually appears in the third trimester of gestation and twin pregnancy is recognized as a risk factor for its development. Case Report: A 25-year-old female patient with no medical history, 2 pregnancies, 1 childbirth and 0 abortions, having a twin pregnancy of 31 weeks' gestation, consulted for abdominal pain, vomiting and jaundice. Acute hepatitis was suspected and it was decided to hospitalize. On admission, an obstetric ultrasonography screened for absent fetal beats, deciding to interrupt the pregnancy. The patient evolved with confusional syndrome and massive epistaxis requiring transfusion. She presented renal failure, hepatic failure, and thrombocytopenia. He entered a Critical Patient Unit with diagnosis of HELLP syndrome requiring support with mechanical ventilation. It persisted with poor clinical evolution, requiring tomography of the abdomen and pelvis showing signs of acute pancreatitis and subcapsular hepatic hematoma. Control examinations aimed at hyperbilirubinemia, elevated transaminases, hypoalbuminemia, hypocholesterolemia and elevated prothrombin time. A diagnosis of acute fatty liver of pregnancy was made. He entered the waiting list for liver transplantation. Subsequently it evolved with spontaneous improvement of the liver function and was able to extubate after two weeks of hospitalization. Discussion: The development of acute fatty liver of pregnancy is infrequent and potentially serious due to early termination of pregnancy and management in critical patient units due to its high mortality.

[Application of the ubiquicidin 29-41 scan in the diagnosis of pyogenic vertebral osteomyelitis]. / Utilidad de la gammagrafía con ubiquicidina 29-41 en el diagnóstico de osteomielitis piógena de columna vertebral.

BACKGROUND: The non-invasive diagnosis of vertebral osteomyelitis is a difficult one. Studies confirm MRI as the gold standard with 92% sensitivity and 94% specificity. Scintigraphy combined with Tc99-Ga67 used to be the procedure of choice before the advent of PET with labeled glucose, which has a high sensitivity and specificity, but cannot distinguish a focus of infection from inflammation. Scintigraphy with UBI29-41 is an infection-specific study that was recently described in the literature. There are no studies showing its value in the diagnosis of vertebral osteomyelitis. OBJECTIVE: The purpose of the study is to show that the Tc99-UBI29-41 scan has 99% sensitivity for vertebral osteomyelitis. METHODS: This is a study of a diagnostic test. The case series was composed of the records of UBI scans performed at the Nuclear Medicine Department, HcHMAE. The scans were interpreted in a blind and independent fashion by 2 experienced observers. The final diagnosis was obtained with the histopathologic study or a microbiologic culture or with the clinical findings after a follow-up of at least 6 months. The sensitivity, specificity, positive and negative predictive values, and the positive and negative probability ratio were determined, always using a 95% confidence interval (CI). The sample size necessary to show 99% sensitivity with a 95% CI and a statistical power of 80% was 15 patients. The concordance with the kappa index was determined. RESULTS: Twenty-seven patients with suspected vertebral osteomyelitis were included; 15 males and 12 females, with a mean age of 50 years (SD = 16). Fourteen patients had a history of surgery and 12 had metallic implants. Nine patients had a history if spinal infiltrations. The number of patients with a positive scan was 20. The sensitivity for detecting pyogenic vertebral osteomyelitis was 100% (CI: 0.901-1) and the specificity was 87.5% (CI: 0.647-0.875). The positive predictive value was 0.95 (CI: 0.859-0.950), and the negative predictive value was 1 (CI: 0.739-1). The intra- and interobserver kappa value was 1. CONCLUSIONS: The UBI scan showed 100% sensitivity and 88% specificity for vertebral osteomyelitis. Although the role of this method in the diagnostic protocol of the patient with suspected vertebral osteomyelitis has not yet been defined, the scan was useful in this group of patients to arrive at a certain diagnosis.