Understanding and Reducing Photothermal Forces for the Fabrication of Au Nanoparticle Dimers by Optical Printing.

Optical printing holds great potential to enable the use of the vast variety of colloidal nanoparticles (NPs) in nano- and microdevices and circuits. By means of optical forces, it enables the direct assembly of NPs, one by one, onto specific positions of solid surfaces with great flexibility of pattern design and no need of previous surface patterning. However, for unclear causes it was not possible to print identical NPs closer to each other than 300 nm. Here, we show that the repulsion restricting the optical printing of close by NPs arises from light absorption by the printed NPs and subsequent local heating. By optimizing heat dissipation, it is possible to reduce the minimum separation between NPs. Using a reduced graphene oxide layer on a sapphire substrate, we demonstrate for the first time the optical printing of Au-Au NP dimers. Modeling the experiments considering optical, thermophoretic, and thermo-osmotic forces we obtain a detailed understanding and a clear pathway for the optical printing fabrication of complex nano structures and circuits based on connected colloidal NPs.

Early Macrophage Infiltration and Sustained Inflammation in Kidneys From Deceased Donors Are Associated With Long-Term Renal Function.

Kidney transplants from living donors (LDs) have a better outcome than those from deceased donors (DDs). Different factors have been suggested to justify the different outcome. In this study, we analyzed the infiltration and phenotype of monocytes/macrophages and the expression of inflammatory and fibrotic markers in renal biopsy specimens from 94 kidney recipients (60 DDs and 34 LDs) at baseline and 4 months after transplantation. We evaluated their association with medium- and long-term renal function. At baseline, inflammatory gene expression was higher in DDs than in LDs. These results were confirmed by the high number of CD68-positive cells in DD kidneys, which correlated negatively with long-term renal function. Expression of the fibrotic markers vimentin, fibronectin, and α-smooth muscle actin was more elevated in biopsy specimens from DDs at 4 months than in those from LDs. Gene expression of inflammatory and fibrotic markers at 4 months and difference between 4 months and baseline correlated negatively with medium- and long-term renal function in DDs. Multivariate analysis point to transforming growth factor-ß1 as the best predictor of long-term renal function in DDs. We conclude that early macrophage infiltration, sustained inflammation, and transforming growth factor-ß1 expression, at least for the first 4 months, contribute significantly to the difference in DD and LD transplant outcome.

Inorganically coated colloidal quantum dots in polar solvents using a microemulsion-assisted method.

The dielectric nature of organic ligands capping semiconductor colloidal nanocrystals (NCs) makes them incompatible with optoelectronic applications. For this reason, these ligands are regularly substituted through ligand-exchange processes by shorter (even atomic) or inorganic ones. In this work, an alternative path is proposed to obtain inorganically coated NCs. Differently to regular ligand exchange processes, the method reported here produces core-shell NCs and the removal of the original organic shell in a single step. This procedure leads to the formation of connected NCs resembling 1D worm-like networks with improved optical properties and polar solubility, in comparison with the initial CdSe NCs. The nature of the inorganic shell has been elucidated by X-ray Absorption Near Edge Structure (XANES), Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Photoelectron Spectroscopy (XPS). The 1D morphology along with the lack of long insulating organic ligands and the higher solubility in polar media turns these structures very attractive for their further integration into optoelectronic devices.

Monocyte implication in renal allograft dysfunction.

Macrophages are involved in the development and progression of kidney fibrosis. The aim of this study was to analyse the phenotype of circulating monocytes and their ability to predict kidney allograft dysfunction in living kidney transplant recipients. Whole blood samples from 25 kidney recipients and 17 donors were collected at five time-points. Monocyte phenotype was analysed by flow cytometry, and interleukin (IL)-10 and soluble CD163 by enzyme-linked immunosorbent assay. One week after transplantation, surface CD163 and IL-10 levels increased significantly from baseline [2·99 ± 1·38 mean fluorescence intensity (MFI) to 5·18 ± 2·42 MFI for CD163; 4·5 ± 1·46 pg/ml to 6·7 ± 2·5 pg/ml for IL-10]. This CD163 increase correlated with 4-month creatinine levels (r = 0·4394, P = 0·04). However, soluble CD163 decreased significantly from baseline at 1 week (797·11 ± 340·45 ng/ml to 576·50 ± 293·60 ng/ml). CD14(+) CD16(-) monocytes increased at 4 months and correlated positively with creatinine levels at 12 and 24 months (r = 0·6348, P = 0·002 and r = 0·467, P = 0·028, respectively) and negatively with Modification of Diet in Renal Disease (MDRD) at 12 months (r = 0·6056, P = 0·003). At 4 months, IL-10 decreased significantly (P = 0·008) and correlated positively with creatinine at 2 years (r = 0·68, P = 0·010) and with CD14(+) CD16(-) monocytes at 4 months (r = 0·732, P = 0·004). At 24 h, levels of human leucocyte antigen D-related declined from 12·12 ± 5·99 to 5·21 ± 3·84 and CD86 expression decreased from 2·76 ± 1·08 to 1·87 ± 0·95. Both markers recovered progressively until 12 months, when they decreased again. These results indicate that monitoring monocytes could be a promising new prognostic tool of graft dysfunction in renal transplant patients.

Fe-Ni porphyrin/mesoporous titania thin film electrodes: a bioinspired nanoarchitecture for photoelectrocatalysis.

Porphyrin and porphyrinoid derivatives have been extensively studied in the assembly of catalysts and sensors, seeking biomimetic and bioinspired activity. In particular, Fe and Ni porphyrins can be used for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) by immobilization of these molecular catalysts on semiconductor materials. In this study, we designed a hybrid material containing a crystalline mesoporous TiO2 thin film in which the catalytic centres are Ni-porphyrin (NiP), Fe-porphyrin (FeP), and a NiP/FeP bimetallic system to assess whether the coexistence of both metalloporphyrins improves the OER activity. The obtained photoelectrodes were physicochemically and morphologically characterized through high-resolution FE-SEM images, UV-vis and Raman spectroscopies, cyclic voltammetry, and impedance measurements. The results show a differential behavior of the mono- and bimetallic porphyrin systems, where the Fe(iii) centre in FeP may increase the acidity and lower the reduction potential of the Ni2+/3+ couple when co-deposited with NiP leading to an improved photoelectrochemical water-oxidation performance. We have validated the cooperative effect of both metal complexes within this novel system, where the µ-peroxo-bridged interaction between Fe and Ni is integrated into a supramolecular heterometallic structure of porphyrins.

Sunlight-Driven Photocatalysis for a Set of 3D Metal-Porphyrin Frameworks Based on a Planar Tetracarboxylic Ligand and Lanthanide Ions.

Metal-porphyrin frameworks (MPFs) with trivalent lanthanide ions are the most sought-after materials in the past decade. Their porosities are usually complemented by optical properties imparted by the metal nodes, making them attractive multifunctional materials. Here, we report a novel family of 3D MPFs obtained through solvothermal reactions between tetrakis(4-carboxyphenyl) porphyrin (H4TCPP) and different lanthanide sources, yielding an isostructural family of compounds along the lanthanide series: [Ln2(DMF)(TCPP)1.5] for Ln = La, Ce, Nd, Pr, Er, Y, Tb, Dy, Sm, Eu, Gd, and Tm. Photoluminescent properties of selected phases were explored at room temperature. Also, the photocatalytic performance exhibited by these compounds under sunlight exposure is promising for its implementation in organic pollutant degradation. In order to study the photocatalytic activity of Ln-TCPPs in an aqueous medium, methylene blue (MB) was used as a contaminant model. The efficiency for MB degradation was Sm > Y > Yb > Gd > Er > Eu > either no catalyst or no light, obtaining more than 70% degradation at 120 min with Sm-TCPP. These results open the possibility of using these compounds in optical and optoelectronic devices for water remediation and sensing.

Zinc porphyrin/mesoporous titania thin film electrodes: a hybrid material nanoarchitecture for photocatalytic reduction.

In this work, photocatalytic reduction of methyl viologen is achieved using zinc tetra(4-N-methylpyridyl)porphine (ZnP) functionalized mesoporous titania thin films (MTTF). Metalloporphyrins are the core of natural systems that harvest energy from the sun. Thus, a bioinspired approach is used, taking advantage of ZnP sensitizing capabilities and MTTF organized structure.

Thermocatalytic CO2 Conversion over a Nickel-Loaded Ceria Nanostructured Catalyst: A NAP-XPS Study.

Despite the increasing economic incentives and environmental advantages associated to their substitution, carbon-rich fossil fuels are expected to remain as the dominant worldwide source of energy through at least the next two decades and perhaps later. Therefore, both the control and reduction of CO2 emissions have become environmental issues of major concern and big challenges for the international scientific community. Among the proposed strategies to achieve these goals, conversion of CO2 by its reduction into high added value products, such as methane or syngas, has been widely agreed to be the most attractive from the environmental and economic points of view. In the present work, thermocatalytic reduction of CO2 with H2 was studied over a nanostructured ceria-supported nickel catalyst. Ceria nanocubes were employed as support, while the nickel phase was supported by means a surfactant-free controlled chemical precipitation method. The resulting nanocatalyst was characterized in terms of its physicochemical properties, with special attention paid to both surface basicity and reducibility. The nanocatalyst was studied during CO2 reduction by means of Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS). Two different catalytic behaviors were observed depending on the reaction temperature. At low temperature, with both Ce and Ni in an oxidized state, CH4 formation was observed, whereas at high temperature above 500 °C, the reverse water gas shift reaction became dominant, with CO and H2O being the main products. NAP-XPS was revealed as a powerful tool to study the behavior of this nanostructured catalyst under reaction conditions.

Elucidating the Role of the Metal Catalyst and Oxide Support in the Ru/CeO2-Catalyzed CO2 Methanation Mechanism.

This study addresses the yet unresolved CO2 methanation mechanism on a Ru/CeO2 catalyst by means of near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) complemented with periodic density functional theory (DFT) calculations. NAP-XPS results show that the switch from H2 to CO2 + H2 mixture oxidizes both the Ru and CeO2 phases at low temperatures, which is explained by the CO2 adsorption modes assessed by means of DFT on each representative surface. CO2 adsorption on Ru is dissociative and moderately endergonic, leading to polybonded Ru-carbonyl groups whose hydrogenation is the rate-determining step in the overall process. Unlike on Ru metal, CO2 can be strongly adsorbed as carbonates on ceria surface oxygen sites or on the reduced ceria at oxygen vacancies as carboxylates (CO2 -δ), resulting in the reoxidation of ceria. Carboxylates can then evolve as CO, which is released either via direct splitting at relatively low temperatures or through stable formate species at higher temperatures. DRIFTS confirm the great stability of formates, whose depletion relates with CO2 conversion in the reaction cell, while carbonates remain on the surface up to higher temperatures. CO generation on ceria serves as an additional reservoir of Ru-carbonyls, cooperating to the overall CO2 methanation process. Altogether, this study highlights the noninnocent role of the ceria support in the performance of Ru/CeO2 toward CO2 methanation.

[Why renal transplant from living donors gives better results than cadaver renal transplant?]. / Por qué el trasplante renal de donante vivo da mejores resultados que el trasplante renalde donante cadáver?

BACKGROUND: According to literature, patient and graft survival is better in living donor renal transplants (LRT) than in cadaver renal transplants (CRT). OBJECTIVE: To study factors that determine the best results in LRT related to those of CRT, found in univariate studies. PATIENTS AND METHODS: Renal transplants (RT) done in Catalonia during the 1990-2004 period, performed in patients over 17 years (135 LRT and 3.831 CRT), have been analyzed (retransplants were not included). The data come from the Renal Patients Transplant Registry (RMRC). Student's t-test and chi2 test have been used for mean and for proportions comparisons, respectively. To analyze univariate and multivariate survival, actuarial method and Cox regression have been used, respectively. Estimated creatinine clearance has been studied and its data have been showed through Selwood modified Analysis. RESULTS: As it happens with other great RT patients series, the RMRC analysis, globally and without any adjustment, shows that patient and graft survival in LRT is better than that obtained with CRT. When we studied which variables explain these results, we found that main factors were smaller recipient age and the short time on dialysis. The great influence of both factors has been published in a large number of papers, explaining the differences obtained on the transplanted renal patient survival. CONCLUSIONS: Once adjusted the analysis by the different factors that influence the survival of the patient and the graft, there are no differences in the obtained results, since the best outcomes of the TRV are due to factors like the smaller recipient age and the advanced TR.

[Pregnancy in recipients of kidney transplantation: effects on mother and child]. / Embarazo en receptoras de trasplante renal: efectos en la madre y en el niño.

When the field of transplantation was first developing, physicians worried about the teratogenicity of immunosuppressive medications and considered pregnancy ill-advised. The purpose of this study is to analyze pregnancy after kidney transplantation and their consequences on mother, graft and child. We review ten pregnant women with kidney transplantation, average of 29 years old and 44 months post-kidney transplantation. The mean glomerular filtration rate was 64 ml/min and the immunosuppression was with prednisone and tacrolimus. We analyze outcomes of different variables before and during pregnancy, and after labour. Pregnancy finished in nine of ten patients. Three patients needed cesarean section and only one patient had a miscarriage on the first term. Blood arterial pressure increased at the end of pregnancy and the creatinine level was stable with a few increase of proteinuria at the third term. We increased the tacrolimus dose to obtain the correct blood levels and any rejection was detected. We had only one patient with preeclampsia that we solved with a cesarean section. Labours were a mean of 37.2 weeks and the mean birth weight of infant was 2,809 grams. Two newborns had prematurity without structural malformations. Pregnancy after kidney transplantation is safe with prednisone and tacrolimus when the renal function is good, proteinuria doesn't exist and blood pressure is controlled.

[Prophylactic and pre-emptive therapy for cytomegalovirus infection in kidney transplant patients using oral valganciclovir]. / Tratamiento profiláctico y anticipado de la infección por citomegalovirus en pacientes trasplantados renales mediante valganciclovir oral.

UNLABELLED: Prophylactic and pre-emptive therapy with oral valganciclovir for cytomegalovirus infection in renal transplant recipients. BACKGROUND: Cytomegalovirus infection is a very important health problem in solid organ transplant recipients (SOT). Once-daily valganciclovir has been shown to be as clinically effective and well tolerated as oral ganciclovir tid in the prevention of CMV infection in high risk SOT recipients. METHODS: The aim of the present study was to evaluate the incidence and severity of CMV disease in 150 renal transplant recipients that received either prophylactic [high risk group (HR), N = 66] or pre-emptive [low risk group (LR), N = 84] therapy with oral valganciclovir (900 mg/day vo) for three months according to their basal risk. Patients were monitored for signs and symptoms of CMV disease and CMV plasma viral load was assessed weekly. RESULTS: A total of 31 patients (47%) of the HR and 26 patients (31%) of the LR presented a positive CMV PCR result. Twelve patients (14.3%) in the LR that had a high viral load (CMV PCR > 1,000 copies/mL) but remained asymptomatic received pre-emptive therapy. Four patients (4.7%) in the LR, after an average time of 35 days after transplant and two patients (4.5%) in the HR, after prophylactic treatment was completed, developed CMV disease. The disease was mild-moderate in most of the cases. Those patients that developed CMV disease responded to treatment with iv ganciclovir for 14 days followed by treatment with oral valganciclovir for up to three months. CONCLUSION: Prophylactic treatment with oral valganciclovir for CMV prevention is only required in high risk solid organ transplant recipients.

Unexpected Optical Blue Shift in Large Colloidal Quantum Dots by Anionic Migration and Exchange.

Compositional changes taking place during the synthesis of alloyed CdSeZnS nanocrystals (NCs) allow shifting of the optical features to higher energy as the NCs grow. Under certain synthetic conditions, the effect of those changes on the surface/interface chemistry competes with and dominates over the conventional quantum confinement effect in growing NCs. These changes, identified by means of complementary advanced spectroscopic techniques such as XPS (X-ray photoelectron spectroscopy) and XAS (X-ray absorption spectroscopy), are understood in the frame of an ion migration and exchange mechanism taking place during the synthesis. Control over the synthetic routes during NC growth represents an alternative tool to tune the optical properties of colloidal quantum dots, broadening the versatility of the wet chemical methods.

Living donor kidney transplantation in catalonia: comparison with cadaveric kidney donors.

INTRODUCTION: We studied the renal transplantation results of living donor compared with cadaveric donor kidney transplantations. PATIENTS AND METHODS: One hundred thirty-six living donor transplantations performed during the period of 1990 to 2003 (group 1) were compared with a control group of 4304 cadaveric donor transplantations (group 2), paired 1:1 with group 1 patients, according to the period of transplantation, the primary renal disease, the transplant number, as well as the recipient and donor ages. RESULTS: There were no differences regarding patient or graft survival during a 10-year follow-up. CONCLUSIONS: The benefit of performing living donor kidney transplantations is the possibility of having the donor available even before beginning dialysis treatment.

Assessment of the arteries in living kidney donors: correlation of magnetic resonance angiography with intraoperative findings.

Comprehensive imaging evaluation of kidney donor anatomy is crucial for selecting candidates for living kidney transplantation and for determining the surgical technique to procure the renal graft. In 76 living renal donors we compared the results of preoperative magnetic resonance angiography (MRA) with the intraoperative findings of arterial anatomy. Donors were evaluated for the number of main renal arteries and the presence of any polar arteries. A total of 80 main renal arteries and five polar arteries were observed at MRA. At surgery, 90 main renal arteries and eight polar arteries were identified. MRA demonstrated a sensitivity, specificity, and overall accuracy of 18%, 98%, and 87%, respectively, for main arteries and 25%, 96%, and 88% for polar arteries. Eleven (14.5%) kidneys displayed more than one main artery and MRA only detected two cases. Eight kidneys had polar arteries and MRA only detected two cases. MRA is a reliable method for presurgical evaluation of renal arteries in potential donors, providing valuable information required by the surgeon. But, as the technique misses small-diameter vessels, it cannot be recommended as the sole diagnostic tool in unclear cases.

Relation between pp65 antigenemia, RT-PCR and viruria for cytomegalovirus detection in kidney transplant recipients.

INTRODUCTION: We compared the efficiency of detection using pp65 antigenemia, reverse transcription-polymerase chain reaction (RT-PCR), and viruria for the diagnosis of cytomegalovirus (CMV) infections after kidney transplantation. PATIENTS AND METHODS: We evaluated 40 renal transplant recipients between weeks 5 and 12 after transplantation, including 179 blood and 181 urine specimens. RESULTS: All positive samples by antigenemia were also positive by PCR. However, in 52 cases only PCR was positive (kappa = 0.134 [P < .001]). Viruria was positive in 66 cases, but only 26 were CMV PCR positive. In 34 cases, viruria was negative and PCR positive (P = .192). CONCLUSION: Detection of DNA in serum is a more sensitive method than antigenemia for the diagnosis of CMV infection. Viruria was not related to the presence of CMV in blood.

Results and complications of 50 laparoscopic nephrectomies for live donor renal transplantation.

Living donors represent 30% of kidneys for renal transplantation. Laparoscopic nephrectomy is the best surgical procedure due to its clear advantages: low morbidity, less blood transfusion requirements, and shorter donor hospitalization. From March 2002 to August 2004, we performed 50 laparoscopic nephrectomies for transplantation to recipients who were prescribed tacrolimus (0.1 mg/kg bid), mycophenolate mofetil (1 gr bid), and prednisone (0.5-1 mg/kg per day PO from 48 hours before transplantation). Mean surgery time was 170 minutes (120-260); warm ischemia time, 3.1 minutes (1.5-10); and cold ischemia time, 1.27 hours (0.85-4). Mean bleeding was 270 cc (100-900), and mean donor hospitalization was 5.5 days (3-9). Four cases required conversion of the laparoscopic procedure to open surgery because of bleeding. Seventy-two hours posttransplantation, the mean plasma creatinine was 170 micromol/L. None of the patients suffered delayed graft function. Eighteen percent experienced acute rejection episodes. Donor and recipient survivals were 100% at 1 year, and graft survival, 94% (kidney losses were due to acute rejection, severe acute pancreatitis, and surgical complications).

Determining factors of the response to hyperhomocysteinemia treatment in renal transplant patients.

Hyperhomocysteinemia (hyperHcy) is a risk factor for cardiovascular disease. The benefits of lowering homocysteinemia (Hcy) in renal transplant recipients through vitamin treatment are not clearly understood. The objective of this study was to establish the demographic, renal, Hcy metabolism, and microinflammation factors that determined the response to folic acid and vitamin B complex treatment in stable patients with renal transplants and hyperHcy. We studied 65 renal transplant patients with baseline hyperHcy. The mean baseline Hcy level of these patients was 22.5 micromol/L. Following treatment it fell to 14.5 micromol/L, an overall reduction of 35.5%. Forty-one patients (63%) were classified as responders; the remainder (37%), nonresponders. A bivariance analysis suggested the only significant differences between responding and nonresponding patients were the pre-treatment Hcy level and the renal function level.

Cardiovascular risk factors in diabetic patients with renal transplants.

There is a progressive increase in cardiovascular events post-renal transplantation and diabetes mellitus (DM) is one of the major cardiovascular risk factors. The objective of this study was to analyze the prevalence of cardiovascular risk factors and nonfatal cardiovascular events among renal transplant recipients, according to the status of their carbohydrate metabolism. We studied 214 renal transplant recipients, among whom 18% diabetic and 82% were nondiabetic. The 16% prevalence of cardiovascular events were higher among the posttransplantation DM (PTDM) group (33%) compared with the other groups, 19% in pre-renal transplantation DM, 17% in altered baseline glycemia, and 13% in normal patients. Diabetic renal transplant recipients showed a greater prevalence of pretransplantation ischemic cardiopathy when they were older and had a higher pretransplantation body mass index (BMI) a heavier smoking habit, significantly increased microinflammation markers, and a greater need for antihypertensive and hypolipidemic treatment. Renal transplant recipients with altered baseline glycemia show greater BMI after transplantation, as well as higher Hb1Ac than patients with normoglycemia.