Tantalum(v) 1,3-propanediolate β-diketonate solution as a precursor to sol–gel derived,metal oxide thin films

Tantalum oxide is ubiquitous in everyday life, from capacitors in electronics to ion conductors for electrochromic windows and electrochemical storage devices. Investigations into sol–gel deposition of tantalum oxide, and its sister niobium oxide, has accelerated since the 1980s and continues to this day. The aim of this study is to synthesize a near UV sensitive, air stable, and low toxicity tantalum sol–gel precursor solution for metal oxide thin films – these attributes promise to reduce manufacturing costs and allow for facile mass production. By utilizing 1D and 2D nuclear magnetic resonance, this study shows that by removing ethanol from the precursor solution at a relatively low temperature and pressure, decomposition of the photosensitive complex can be minimized while obtaining a precursor solution with sufficient stability for storage and processing in the atmosphere. The solution described herein is further modified for inkjet printing, where multiple material characterization techniques demonstrate that the solution can be utilized in low temperature, photochemical solution deposition of tantalum oxide, which is likely amorphous. Tested substrates include amorphous silica, crystalline silicon wafer, and gold/titanium/PET foil. The hope is that these results may spark future investigations into electronic, optical, and biomedical device fabrication with tantalum oxide, and potentially niobium oxide, based films using the proposed synthesis method.

Synthesis of tantalum(v) 1,3-propanediolate β-diketonate solution and use in photochemical solution deposition to form tantalum oxide films.     

Slowness curve surface acoustic wave transducers for optimized acoustic streaming

Surface acoustic waves can induce force gradients on the length scales of micro- and nanoparticles, allowing precise manipulation for particle capture, alignment and sorting activities. These waves typically occupy a spatial region much larger than a single particle, resulting in batch manipulation. Circular arc transducers can focus a SAW into a narrow beam on the order of the particle diameter for highly localised, single-particle manipulation by exciting wavelets which propagate to a common focal point. The anisotropic nature of SAW substrates, however, elongates and shifts the focal region. Acousto-microfluidic applications are highly dependent on the morphology of the underlying substrate displacement and, thus, become dependent on the microchannel position relative to the circular arc transducer. This requires either direct measurement or computational modelling of the SAW displacement field. We show that the directly measured elongation and shift in the focal region are recapitulated by an analytical model of beam steering, derived from a simulated slowness curve for 128° Y-cut lithium niobate. We show how the negative effects of beam steering can be negated by adjusting the curvature of arced transducers according to the slowness curve of the substrate, for which we present a simple function for convenient implementation in computational design software. Slowness-curve adjusted transducers do not require direct measurement of the SAW displacement field for microchannel placement and can capture smaller particles within the streaming vortices than can circular arc IDTs.

Adjusting focused IDT curvature according to the substrate slowness curve permits better focusing for enhanced acoustofluidic microparticle capture.     

Solvent-assisted linker exchange as a tool for the design of mixed-linker MIL-140D structured MOFs for highly selective detection of gaseous H2S

A MIL-140D-sdc framework has been used as a highly stable backbone for the introduction of 4,4′-azobenzene dicarboxylic acid (H₂abdc) via solvent-assisted ligand exchange (SALE). The implemented azo groups can serve as coordination sites for copper ions. These can exchange ligands with different gases, but show a high selectivity against H₂S, which makes this material promising for potential sensor applications.

Solvent-assisted linker exchange was used as tool to modify a MIL-140D-sdc (sdc = 4,4′-stilbenedicarboxylate) MOF with azostilbene dicarboxylic acid. The azo groups can act as coordination sites for copper ions and allow the use of this material as sensor for gaseous H₂S.

Hydrogen sulfide (H₂S) is a toxic gas with harmful effects on human health and is responsible for different diseases, like liver cirrhosis.¹ At concentrations above just 50 ppm, irritation of the respiratory tract can occur.² For the detection of H₂S, chemical sensors containing semiconducting metal oxides are widely used. Although these exhibit high sensitivities, they also have some disadvantages due to their high working temperatures and a lack of selectivity.³Especially in the areas of selectivity and cross-sensitivity, metal–organic frameworks (MOFs) can overcome the limits that plague many other sensors. Due to their modular design built up by metal nodes and organic linker molecules, they can be tailored to the desired application.⁴ Functionalities attached to the linkers of MOFs are often required in order to be able to use these materials for sensor applications.⁵Many MOFs are described for the detection of H₂S. Apart from one example of a capacitive sensor,⁶ the detection is almost always based on a fluorescence turn-on probe. Here functional groups of the MOF (–N₃ or –NO₂) are reduced by H₂S to amino groups resulting in turning on the fluorescence of the linker. However, in these investigations the MOFs are dispersed in buffered aqueous or ethanolic solutions.⁷ In addition, no gaseous H₂S is used, but sulfides-containing sodium salts such as Na₂S, that dissociate in solution to HS⁻, which is required for the reaction.⁸ To the best of our knowledge, only one example is described in literature where a MOF is used for a luminescent-based detection of gaseous H₂S.⁹Azo components have the special ability to coordinate metal ions. This has already been investigated in detail with individual azo compounds and metal salts of palladium¹⁰ or copper.^11,12 Until now, a transfer of this reaction behaviour into a MOF is rare and not yet described for copper species but for palladium species.¹³ Nevertheless, these copper-azo complexes can be used for the colourimetric detection of both aqueous HS⁻ and gaseous H₂S.¹⁴ The sensor principle is based on a displacement reaction. The coordinated copper ions react with gaseous H₂S to CuS as already shown with CuO-loaded metal oxide semiconductors.¹⁵ Considering copper-based MOFs such as the HKUST-1, they show a lack of stability under normal conditions, making them unsuitable for use in sensor technology. Nevertheless, a reaction between H₂S and the metal centres is still possible, however, this leads to the formation of CuS and the complete breakdown of the framework.¹⁶With the UiO family, a isoreticular series of Zr-based MOFs was reported.¹⁷ Particularly, the UiO-66 and its derivatives exhibit an exceptional thermal and chemical stability. By the use of the same precursors but higher synthesis temperatures, Guillerm et al. presented highly stable Zr-MOFs, the so-called MIL-140 series.¹⁸ In MIL-140 frameworks, there are one-dimensional chains of zirconium oxide (c.n. 7) as inorganic building units (IBUs) orientated parallel to the c-axis of the structures. Each chain is connected via linker molecules to six other chains resulting in a one-dimensional pore system (see ESI Fig. S1^†). Especially those MOFs with longer linker molecules exhibit an improved stability in comparison to their UiO analogues. This can be explained with the different structures of these compounds.^18,19By using post-synthetic modifications (PSM) further functionalized MOF materials can be obtained.²⁰ In case of exchanging an unfunctionalized linker molecule with a functionalized, the solvent-assisted ligand exchange (SALE) is an attractive possibility to adjust the properties of an already synthesized MOF and enhance the tunability.²¹We recently reported a low-temperature synthesis of MIL-140 frameworks and a new MIL-140-structured MOF, based on 4,4′-stilbenedicarboxylic acid (H₂sdc), the MIL-140D-sdc (see Table S1 and ESI Fig. S1^†).²² This MOF shows a high thermal and chemical stability which can be compared to the former reported MIL-140 MOFs.¹⁸ A synthesis for an azo-based MIL-140D-H with H₂abdc as linker is also described in literature (see ESI Table S1^†).²³ However, the resulting framework is instable under ambient conditions and a transition to a unknown nearly nonporous phase occurs after only a few days.²³ These are unfavourable properties for a stable sensor material.In this work, we demonstrate the efficiency of the SALE to produce MOFs that combine high stability and high functionality. Therefore, we use the MIL-140D-sdc framework as stable backbone. For the preparation of the mixed-linker MOF (MIL-140D-sdc/abdc), we substitute sdc²⁻ with abdc²⁻via SALE by immersing the MIL-140D-sdc in a DMF solution of H₂abdc and storing it at 120 °C for 24 h (up to 1 eq. H₂abdc with respect to the Zr cations in the framework, see ESI Table S2^†).For verifying the successful SALE, the exchanged MOF samples were disassembled and analysed with ¹H-NMR spectroscopy (ESI Fig. S2 and S3^†). The evaluation has shown that the level of conversion rises with an increasing amount of provided linkers (H₂abdc). The maximum exchange rate is slightly below 50%.Powder X-ray diffraction (PXRD) is used to check the stability of the compounds after each reaction step. After exchanging the MIL-140D-sdc with abdc²⁻ at 120 °C, the solids exhibit the same diffraction pattern, but the colour has changed from white to reddish (Fig. 1a).Open in a separate windowFig. 1Presentation of the conducted modification, incorporation and gas exposure with MIL-140D-sdc structured MOFs. (a) Powder XRD pattern of the samples prepared with a SALE starting from MIL-140D-sdc and the resulting colour change with different amounts of H₂abdc. (b) Powder XRD pattern after the incorporation of increasing amounts of Cu²⁺ into the MIL-140D-sdc/abdc framework and the observed colour change and (c) powder XRD pattern and pictures of the same materials after the exposure to 100 ppm H₂S.The advantage of MIL-140 structured MOFs results from the stacking of the linkers and the resulting short distance between the azo groups. This arrangement should be promising for the coordination of copper ions, since in literature the molecules either have additional functional groups for the coordination or the metal ions are located between two azo groups.²⁴ Subsequently, copper ions are incorporated into the framework. For this purpose, the linker-exchanged MOF is dispersed in DMF and stirred for 1 hour at room temperature while adding copper chloride. The amount of copper chloride used is identical to the previously used amount of added linker H₂abdc (see ESI Table S3^†). After the copper ions were integrated into the framework, the colour of the MOF changed from red to green (Fig. 1b). Although the samples still show the same diffraction pattern, a closer look reveals differences. Thus, the 200-reflection (at 5° 2Θ) shifts slightly to smaller angles and in the range of 10° 2Θ the intensity of two reflections increase (ESI Fig. S4^†). Neither the shifted reflection nor the colour change can be observed during the treatment of UiO-abdc and MIL-140D-H with copper chloride. Additionally, pure MIL-140D-H appears not to be stable during this reaction (ESI Fig. S5 and S6^†).Nitrogen physisorption measurements verified that there is no significant quantity of linker molecules in the tunnel-like pores after the SALE (ESI Fig. S12 and Table S5^†). In order to demonstrate that the integrated copper ions do not inhibit the accessibility of the pores, N₂ physisorption measurements have been repeated (ESI Fig. S13^†). Indeed, the experimental BET areas barely change and are only about 100 m² g⁻¹ lower (ESI Table S6^†). It can therefore be assumed that the copper ions are coordinated at the azo groups of the linkers and thus hardly contribute to a loss of surface area.For further simplification, at this point the focus is on the samples with the highest exchanged amount of linker and highest stored quantity of Cu²⁺ (1 eq. each). For a more detailed evaluation of the pore size and thus the location of the incorporated copper ions, argon physisorption measurements were carried out. Compared to the originally used sample MIL-140D-sdc, the BET areas are only slightly reduced and also the calculated pore size distributions for all samples show a good correlation (Fig. S15, S16 and Table S8^†). Both measurements indicate a coordination of the copper ions at the azo groups of the linkers. Furthermore, this result contradicts an excessive adsorption of the copper ions in the tunnel-like pores.The amount of copper coordinated in the MOF is estimated by EDX spectroscopy. For this purpose, the MOF was offered two different quantities of copper salt (0.5 and 1.0 eq.) for complexation. In comparison to the SALE sample, the EDX measurements show the same copper content of 0.4 copper atoms per sum formula, regardless of whether 0.5 or 1.0 eq. copper salt was added (see ESI Fig. S17–S19 and Table S9^†). The similar value is due to the fact that only half of the linkers are exchanged during the SALE and again suggests the coordination of the copper ions at the azo groups.The thermogravimetric data are a further indication for the successful storage of Cu²⁺ in the framework. The sample obtained after the SALE shows a similar thermal decomposition as the starting material MIL-140D-sdc. Both materials have a thermal stability of about 350 °C, but the residual mass is lower than calculated in case of the SALE sample (ESI Fig. S21 and Table S10^†). After incorporation, the residual mass increases by approximately 4.5m%, which is equivalent to a copper amount of approximately 0.45 per sum formula and in good agreement with the EDX spectroscopy. The reflections of the powder diffraction pattern of the residue can be accurately assigned to ZrO₂ and CuO (see ESI Fig. S7^†). In addition, the percentage of guests in the framework is increasing drastically. This could be an indication that the copper ions act as Lewis acidic sites where solvent molecules preferentially coordinate. In order to estimate the Lewis acidity of a MOF, the shift of the acetone absorption band can be considered.²⁵ In the presence of strongly Lewis-acidic MOFs, the stretching vibration of the carbonyl group shifts to smaller wave numbers. In this case, the acetone vibration is located at 1690 cm⁻¹ and thus 25 cm⁻¹ lower than for uncoordinated acetone (see ESI Fig. S10^†).In the last step, the incorporated Cu²⁺ ions will be used for the detection of H₂S. With this approach it is possible to transfer the properties of the molecular complexes¹¹ into a solid state material, as we have already shown with a calixarene-based MOF for highly selective NO₂ detection.²⁶ It is generally assumed that the implicit chemical reaction is the formation of CuS.¹⁵ Upon this reaction, a fast and impressive colour change occurs from green to black which can be simply observed with the naked eye. Taking the diffraction patterns into account, it is noticeable that the above-mentioned shift of the 200-reflection is reversed upon H₂S exposure, indicating a change in the coordination of the copper ions (see Fig. 1c and ESI Fig. S4^†). After the exposure to H₂S, the BET area of all samples is drastically reduced (see ESI Fig. S14 and Table S7^†) which can be explained by pore blocking effects due to CuS formation.The formation of CuS can additionally be verified with Raman spectroscopy. Here, a weak CuS band can be found at 471 cm⁻¹ (see ESI Fig. S11^†). Again, this is an indication for the formation of CuS located inside the pore channels or on the surface of the MOFs as pore blocker. This is also an explanation for the decrease of the BET surfaces from the physisorption measurements. After the MOF has been exposed to H₂S, the acetone vibration disappears completely from the IR spectrum. This observation supports the thesis that the coordination of the copper ions at the azo groups and thus the Lewis acidic effect is no longer present after this step.Additionally, the experimental residue of the MOF is similar to the Cu²⁺ incorporated sample (see ESI Fig. S21 and Table S10^†) and is composed of ZrO₂ and CuO (see ESI Fig. S8^†). Moreover, the EDX measurement show a sulphur content in this sample which is comparable to the amount of copper and obviously CuS is formed (see ESI Fig. S20 and Table S9^†).The chemical reaction of the sensor response is the formation of CuS and the associated colour change from green to black. For the application as H₂S sensor material, the spectroscopic characteristics were determined. As already can be seen in the photographs in Fig. 1, the colouration becomes more pronounced with increasing amount of provided linker during the SALE and thus also of the amount of incorporated Cu²⁺. This observation is supported by the UV/Vis measurements. Here, the absorption also intensifies with increasing amounts of H₂abdc after the SALE in the range between 430 and 500 nm. The pure MIL-140D-sdc shows no absorption in this region at all (see ESI Fig. S22a^†). The integration of azo groups is essential for the incorporation of copper ions into the MOF and thus for the detection of H₂S. When a pure MIL-140D-sdc is immersed in a copper chloride solution it can be shown that no copper is coordinated by the MOFs by comparison of the UV/Vis spectra. The absorption does not change because no copper ions can be complexed by the sdc²⁻ linker of pure MIL-140D-sdc. When the copper treated MIL-140D-sdc was exposed for 30 minutes to 100 ppm H₂S no measurable difference in the spectra occurs (see Fig. S24^†). As a result, it can be concluded that no copper ions were deposited in the framework at all.After the incorporation of copper ions in the MIL-140D-sdc/abdc, a second absorption maximum at 730 nm is visible (see ESI Fig. S22b^†). As before, the maximum absorption increases with the amount of copper salt used. After exposure to H₂S, all samples immediately change their colour, whereby the highest absorption can be observed in the sample with the highest copper and abdc²⁻ content. At this point, the entire absorption in the visible range of the light spectrum increases (see ESI Fig. S22c and S23^†).During a 30 minute exposure to 100 ppm H₂S a cycled UV/Vis measurement was conducted to observe directly the change in the absorbance. Within less than 1 minute, an increase of the absorption between 550 and 600 nm is visible. After 30 minutes the saturation is reached and absorbance is approximately 450 percent higher compared to the starting material after the Cu²⁺ incorporation (see Fig. 2). For a more precise analysis, the sample was exposed to 100 ppm H₂S for 30 minutes and the absorbance at 580 nm was recorded every five seconds. Here the MOF exhibits almost no absorption after the incorporation of Cu²⁺. After the exposure to H₂S, the absorbance increases immediately and is again reaching a saturation point with an absorbance twice as high (see Fig. 3).Open in a separate windowFig. 2UV/Vis spectra of the MIL-140D-sdc/abdc after the SALE with H₂abdc (red), after the incorporation of Cu²⁺ (green) and after the exposure to 100 ppm H₂S with different time steps ranging from 1 to 30 minutes.Open in a separate windowFig. 3UV/Vis measurement of the Cu²⁺ incorporated sample (1 eq.) at 580 nm. Before the gas exposure (100 ppm H₂S) a baseline was measured under room conditions.The next step was to investigate the selectivity. For this purpose, the MOF was exposed to various gases such as CO₂ and CO (100 ppm), NO₂ (10 ppm) or stored in an NH₃ and diethyl ether (DEE) atmosphere for 30 minutes. In terms of stability, a partly decomposition occurs only in presence of CO due to its interaction with the azo group (see ESI Fig. S9^†).²⁷ Furthermore, the exposure to these gases results in a colour change for each sample, which can be explained by a ligand exchange at the coordinated copper ions (ESI Fig. S25^†).²⁸ Each sample was again investigated with UV/Vis spectroscopy and the main differences in the spectra are in the range of 400 to 550 and 650 to 800 nm (see ESI Fig. S26^†).The other examined gases cause only minor changes in the range of 580 nm. Only in the case of H₂S a significant change in the spectrum at this wavelength was observed, which should enable quantitative detection of this gas. The absorbances of the different samples at 580 nm are compared and set in relation to the original absorbance of the copper stored sample. The result is shown in Fig. 4, which demonstrates the high selectivity of this material for H₂S measured under these conditions.Open in a separate windowFig. 4Comparison of the differences in the absorbance of the sensor material in the presence of different gases (exposure time: 30 minutes). The measured values are all given in relation to the starting material whose absorbance was defined as 100%.In summary, it was demonstrated that through the post-synthetic step of the SALE a mixed-linker MOF has been obtained, the composition of which can be controlled by the amount of H₂abdc used in the SALE process. Furthermore, the new MIL-140D-sdc/abdc combines the stability of the MIL-140D-sdc framework and the functionality of the introduced azo groups. This again emphasizes the unique nature of the SALE for the production of differently functionalized frameworks and increases the tunability of manufactured materials. For the first time it was possible to use these linkers in a porous solid as coordination sites for copper ions. The porosity of the MOF is barely affected, making the coordinated metal ions accessible to guests. The guests can be different gases that coordinate under a ligand exchange with the copper ions. Nevertheless, this material has a high selectivity towards H₂S, which is expressed by the colour change from green to black, most likely due to the formation of CuS.The MIL-140D-sdc/abdc seems to be an interesting starting material for the coordination of various metals, due to the close arrangement of the linkers. Further, more elaborated, functional groups could help to optimize the sensing process or enhance the reversibility of the sensing reaction. This property can be used for further post-synthetic modifications of the linker and might also result in other attractive sensor materials.     

Does the cement stiffness affect fatigue fracture strength of vertebrae after cement augmentation in osteoporotic patients?

Purpose

Normal progression of osteoporosis or the rigid reinforcement of the fractured vertebral body with polymethyl methacrylate (PMMA) cement is being discussed as a cause for adjacent-level fractures after vertebroplasty. The purpose of this study was to investigate whether augmentation with low stiffness cement can decrease the risk of adjacent-level fractures in low-quality bone.

Methods

Eighteen female osteoporotic lumbar specimens (L1–L5) were harvested and divided into three groups according to bone mineral density: (I) native; (II) PMMA; (III) modified PMMA (lower stiffness). For the PMMA and modified PMMA groups, a compression fracture was first mechanically induced in L3, and then the fracture received vertebroplasty treatment. The cement stiffness reduction of the modified PMMA group was achieved via an addition of 8 mL of serum to the typical PMMA base. All specimens were exposed to cyclic loading (4 Hz) and a stepwise increasing applied peak force. Cement stiffness was tested according to ISO 5833.

Results

A 51 % decrease in cement stiffness was achieved in the modified PMMA group (954 ± 141 vs. 1,937 ± 478 MPa, p < 0.001). Fatigue fracture force (the force level during cyclic loading at which the deformation experienced a sudden increase; FFF) was significantly affected by bone quality (r ² = 0.39, p = 0.006) and by the initial fracture force (the force necessary to create the initial fracture in L3 prior to augmentation; r ² = 0.82, p < 0.001). Using initial fracture force as a covariate, the FFF of the modified PMMA group (1,764 ± 49 N) was significantly higher than in the PMMA group (1,544 ± 55 N; p = 0.03).

Conclusions

A possible method to reduce adjacent-level fractures after vertebroplasty in patients with reduced bone quality could be the use of a lower modulus cement. Therefore, mixing cement with biocompatible fluids could prove useful to tailor cement properties in the operating theater.     

The influence of clinical course after lung transplantation on rehabilitation success

Pulmonary rehabilitation (PR) is a cornerstone of treatment following lung transplantation (LTx). The aim of this study was to observe the influence of a prolonged postsurgical clinical course on success of a 3‐week inpatient PR. LTx recipients were divided according to their clinical course defined by their individual length of stay (LOS) in the transplant center (cohort 1: LOS >; cohort 2: ≤42 days). Peak work rate (PWR), maximum oxygen uptake (VO_2max), 6‐min walk distance (6‐MWD), vital capacity (VC), forced expiratory volume in one second (FEV1), physical activity of daily life (ADL), and health‐related quality of life (HRQoL) measured using Short Form 36 questionnaire (SF36) were assessed at beginning and completion of PR. A total of 138 patients were included (LOS >42 days: 30; LOS ≤42 days: 108). At completion, physical functioning (VC, FEV1, PWR, VO_2max, 6‐MWD, ADL), and HRQoL (all SF36 domains) improved in each cohort (P < 0.05). No differences were found in between both cohorts in VC, FEV1, and ADL (n.s.), but in PWR, 6‐MWD, and the SF36 domain ‘physical functioning’ (P < 0.05). A 3‐week inpatient PR improves physical functioning despite prolonged hospitalization. HRQoL is close to normal. (ClinicalTrials.gov. identifier: NCT00759538)     

Computer-assisted fluoroscopic navigation of percutaneous spinal interventions

Purpose

Percutaneous spine procedures may occasionally be difficult and subject to complications. Navigation using a dynamic reference base (DRB) may ease the procedure. Yet, besides other shortcomings, its fixation demands additional incisions and thereby defies the percutaneous character of the procedure.

Methods

A new concept of atraumatic referencing was invented including a special epiDRB. The accuracy of navigated needle placement in soft tissue and bone was experimentally scrutinised. Axial and pin-point deviations from the planned trajectory were investigated with a CT-based 3D computer system. Clinical evaluation in a series of ten patients was also done.

Results

The new epiDRB proved convenient and reliable. Its fixation to the skin with adhesive foil provided a stable reference for navigation that improves the workflow of percutaneous interventions, reduces radiation exposure and helps avoid complications.

Conclusions

Percutaneous spine interventions can be safely and accurately navigated using epiDRB with minimal trauma or radiation exposure and without additional skin incisions.     

Everolimus immunosuppression in de novo heart transplant recipients: What does the evidence tell us now?

The efficacy of everolimus with reduced cyclosporine in de novo heart transplant patients has been demonstrated convincingly in randomized studies. Moreover, everolimus-based immunosuppression in de novo heart transplant recipients has been shown in two randomized trials to reduce the increase in maximal intimal thickness based on intravascular ultrasound, indicating attenuation of cardiac allograft vasculopathy (CAV). Randomized trials of everolimus in de novo heart transplantation have also consistently shown reduced cytomegalovirus infection versus antimetabolite therapy. In maintenance heart transplantation, conversion from calcineurin inhibitors to everolimus has demonstrated a sustained improvement in renal function. In de novo patients, a renal benefit may only be achieved if there is an adequate reduction in exposure to calcineurin inhibitor therapy. Delayed introduction of everolimus may be appropriate in patients at high risk of wound healing complications, e.g. diabetic patients or patients with ventricular assist device. The current evidence base suggests that the most convincing reasons for use of everolimus from the time of heart transplantation are to slow the progression of CAV and to lower the risk of cytomegalovirus infection. A regimen of everolimus with reduced-exposure calcineurin inhibitor and steroids in de novo heart transplant patients represents a welcome addition to the therapeutic armamentarium.     

Intramedullary nailing of humeral diaphyseal fractures. Is distal locking really necessary?

Purpose:

Distal interlocking is regarded as an inherent part of the antegrade humeral nailing technique, but it exposes both the patient and surgeon to radiation, is time consuming, and has a potential risk of damaging neurovascular structures. We have presented our technique of diaphyseal humeral nailing without any distal interlocking in this paper.

Materials and Methods:

We have presented a series of 64 consecutive patients (33 male and 31 female, mean age: 41.5 years) with humeral shaft fractures treated with antegrade rigid intramedullary nailing without distal interlocking following a strict intra and postoperative protocol. According to the AO classification, there were 36 type A fractures, 22 type B, and 6 type C. Nails were inserted unreamed or by using limited proximal reaming and they were fitted as snuggly as possible into the medullary canal. After impaction of the nail into the fossa, we carefully tested rotational stability of fixation by checking any potential external rotation when the arm was slightly turned externally and left to the gravity forces. We were ready to add distal screws, but that was not required in these cases. Follow-up assessment included fracture union, complications and failures, and the final clinical outcome at minimum 2-year follow-up using the parameters of the constant score.

Results:

All fractures, except two, united between the 4^th and 5^th postoperative month. In one case, nail was exchanged with plate, and, in another, a larger nail was used at a second surgery. Shoulder function according to constant score, at a minimum of 2-year follow-up, was excellent or very good in 93.7% of the patients.

Conclusions:

Provided that some technical issues are followed, the method reduces intraoperative time and radiation exposure and avoids potential damage to neurovascular structures.     

Nephrostomy in percutaneous nephrolithotomy (PCNL): does nephrostomy tube size matter? Results from The Global PCNL Study from The Clinical Research Office Endourology Society

Purpose

To explore the relationships between nephrostomy tube (NT) size and outcome of percutaneous nephrolithotomy (PCNL).

Methods

The Clinical Research Office of the Endourological Society (CROES) prospectively collected data from consecutive patients treated with PCNL over a 1-year period at 96 participating centers worldwide. This report focuses on the 3,968 patients who received a NT of known size. Preoperative, surgical procedure and outcome data were analyzed according to NT size, dividing patients into two groups, namely small-bore (SB; nephrostomy size ≤ 18 Fr) and large-bore (LB; nephrostomy size > 18 Fr) NT.

Results

Patients who received a LB NT had a significantly lower rate of hemoglobin reduction (3.0 vs. 4.3 g/dL; P < 0.001), overall complications (15.8 vs. 21.4 %; P < 0.001) and a trend toward a lower rate of fever (9.1 vs. 10.7 %). Patients receiving a LB NT conversely had a statistically, though not clinically significant, longer postoperative hospital stay (4.4 vs. 4.2 days; P = 0.027). There were no differences in urinary leakage (0.9 vs. 1.3 %, P = 0.215) or stone-free rates (79.5 vs. 78.1 %, P = 0.281) between the two groups.

Conclusions

LB NTs seem to reduce bleeding and overall complication rate. These findings would suggest that if a NT has to be placed, it should better be a LB one.