Partial Hydrolysis of Diphosphonate Ester During the Formation of Hybrid TiO2 Nanoparticles: Role of Acid Concentration

The hydrolysis of the phosphonate ester linker during the synthesis of hybrid (organic-inorganic) TiO2 nanoparticles is important when forming porous hybrid organic-inorganic metal phosphonates. In the present work, a method was utilized to control the in-situ partial hydrolysis of diphosphonate ester in the presence of a titania precursor as a function of acid content, and its impact on the hybrid nanoparticles was assessed. Organodiphosphonate esters, and more specific, their hydrolysis degree during the formation of hybrid organic-inorganic metal oxide nanoparticles, are relatively under explored as linkers. Here, a detailed analysis on the hydrolysis of tetraethyl propylene diphosphonate ester (TEPD) as diphosphonate linker to produce hybrid TiO2 nanoparticles is discussed as a function of acid content. Quantitative solution NMR spectroscopy revealed that during the synthesis of TiO2 nanoparticles, an increase in acid concentration introduces a higher degree of partial hydrolysis of the TEPD linker into diverse acid/ester derivatives of TEPD. Increasing the HCl/Ti ratio from 1 to 3, resulted in an increase in degree of partial hydrolysis of the TEPD linker in solution from 4 % to 18.8 % under the applied conditions. As a result of the difference in partial hydrolysis, the linker-TiO2 bonding was altered. Upon subsequent drying of the colloidal TiO2 solution, different textures, at nanoscale and macroscopic scale, were obtained dependent on the HCl/Ti ratio and thus the degree of hydrolysis of TEPD. Understanding such linker-TiO2 nanoparticle surface dynamics is crucial for making hybrid organic-inorganic materials (i. e. (porous) metal phosphonates) employed in applications such as electronic/photonic devices, separation technology and heterogeneous catalysis.

Self-Induced and Progressive Photo-Oxidation of Organophosphonic Acid Grafted Titanium Dioxide

While synthesis-properties-performance correlations are being studied for organophosphonic acid grafted TiO₂ , their stability and the impact of the exposure conditions on possible changes in the interfacial surface chemistry remain unexplored. Here, the impact of different ageing conditions on the evolution of the surface properties of propyl- and 3-aminopropylphosphonic acid grafted mesoporous TiO₂ over a period of 2 years is reported, using solid-state ³¹ P and ¹³ C NMR, ToF-SIMS and EPR as main techniques. In humid conditions under ambient light exposure, PA grafted TiO₂ surfaces initiate and facilitate photo-induced oxidative reactions, resulting in the formation of phosphate species and degradation of the grafted organic group with a loss of carbon content ranging from 40 to 60 wt %. By revealing its mechanism, solutions were provided to prevent degradation. This work provides valuable insights for the broad community in choosing optimal exposure/storage conditions that extend the lifetime and improve the materials' performance, positively impacting sustainability.

Amino-Alkylphosphonate-Grafted TiO2: How the Alkyl Chain Length Impacts the Surface Properties and the Adsorption Efficiency for Pd

Amino-alkylphosphonic acid-grafted TiO₂ materials are of increasing interest in a variety of applications such as metal sorption, heterogeneous catalysis, CO₂ capture, and enzyme immobilization. To date, systematic insights into the synthesis-properties-performance correlation are missing for such materials, albeit giving important know-how towards their applicability and limitations. In this work, the impact of the chain length and modification conditions (concentration and temperature) of amino-alkylphosphonic acid-grafted TiO₂ on the surface properties and adsorption performance of palladium is studied. Via grafting with aminomethyl-, 3-aminopropyl-, and 6-aminohexylphosphonic acid, combined with the spectroscopic techniques (DRIFT, ³¹P NMR, XPS) and zeta potential measurements, differences in surface properties between the C1, C3, and C6 chains are revealed. The modification degree decreases with increasing chain length under the same synthesis conditions, indicative of folded grafted groups that sterically shield an increasing area of binding sites with increasing chain length. Next, all techniques confirm the different surface interactions of a C1 chain compared to a C3 or C6 chain. This is in line with palladium adsorption experiments, where only for a C1 chain, the adsorption efficiency is affected by the precursor concentration used for modification. The absence of a straightforward correlation between the number of free NH₂ groups and the adsorption capacity for the different chain lengths indicates that other chain-length-specific surface interactions are controlling the adsorption performance. The increasing pH stability in the order of C1 < C3 < C6 can possibly be associated to a higher fraction of inaccessible hydrophilic sites due to the presence of folded structures. Lastly, the comparison of adsorption performance and pH stability with 3-aminopropyl(triethoxysilane)-grafted TiO₂ reveals the applicability of both grafting methods depending on the envisaged pH during sorption.

Selective Pd recovery from acidic leachates by 3-mercaptopropylphosphonic acid grafted TiO2: does surface coverage correlate to performance?

Modification of metal oxides with organophosphonic acids (PAs) provides the ability to control and tailor the surface properties. The metal oxide phosphonic acid bond (M-O-P) is known to be stable under harsh conditions, making PAs a promising candidate for the recovery of metals from complex acidic leachates. The thiol functional group is an excellent regenerable scavenging group for these applications. However, the research on organophosphonic acid grafting with thiol groups is very limited. In this study, four different metal sorbent materials were designed with different thiol surface coverages. An aqueous-based grafting of 3-mercaptopropylphosphonic acid (3MPPA) on mesoporous TiO₂ was employed. Surface grafted thiol groups could be obtained in the range from 0.9 to 1.9 groups per nm². The different obtained surface properties were studied and correlated to the Pd adsorption performance. High Pd/S adsorption efficiencies were achieved, indicating the presence of readily available sorption sites. A large difference in their selectivity towards Pd removal from a spend automotive catalyst leachate was observed due to the co-adsorption of Fe on the titania support. The highest surface coverage showed the highest selectivity (K _d: 530 mL g^-1) and adsorption capacity (Q _max: 0.32 mmol g^-1) towards Pd, while strongly reducing the co-adsorption of Fe on remaining TiO₂ sites.

Results of surgical treatment of cervical esophageal diverticula

On the basis of 20 years' experience, the authors present the immediate and long-term results of operative treatment of Zenker's diverticulum. Comparison of two methods of surgery - diverticulopexia (in 21 patients) and excision (in 16), both associated with upper esophageal sphincter myotomy - shows good immediate and longterm results (from 1 to 19 years), with disappearance of symptoms (dysphagia) in all patients. There was no perioperative mortality. Postoperative complications were most commonly of pulmonary origin and were observed in a third of patients in both groups. In two patients from the group treated with excision, a leak from the suture line occurred, which healed spontaneously. These two patients had transient dysphagia in the postoperative period. On the basis of this analysis, the authors conclude that diverticulopexia is a safer surgical procedure than excision, giving less complications and a very good long-term functional result.

[Results of surgical treatment for Zenker's diverticula]

From 1976 to 1996, thirty nine patients were surgically treated for pharyngoesophageal diverticulum. The present study aimed to compare two methods of operative treatment of Zenker's diverticulum: excision (group I) and pexy, both of which were associated with upper esophageal sphincter myotomy. The main indication for surgery was dysphagia. The diagnosis of Zenker's diverticulum was based on clinical symptoms and the result of upper GI tract barium examination. In 75% of patients the diameter of diverticulum exceeded 2 cm. No patient died in the perioperative period. The main complications observed in the postoperative period were of pulmonary origin. In group I (excision) a leakage from the suture line occurred in 2 patients (12.5%). Time of follow-up ranged from 1 to 20 years (mean: 7 years). The comparison of both methods of treatment employed is in favour of diverticulopexy, being a safer and less complications-bearing method, although both of them give similar functional results.

Results of surgical treatment of cervical esophageal diverticula

On the basis of 20 years' experience, the authors present the immediate and long-term results of operative treatment of Zenker's diverticulum. Comparison of two methods of surgery--diverticulopexia (in 21 patients) and excision (in 16), both associated with upper esophageal sphincter myotomy--shows good immediate and long-term results (from 1 to 19 years), with disappearance of symptoms (dysphagia) in all patients. There was no perioperative mortality. Postoperative complications were most commonly of pulmonary origin and were observed in a third of patients in both groups. In two patients from the group treated with excision, a leak from the suture line occurred, which healed spontaneously. These two patients had transient dysphagia in the postoperative period. On the basis of this analysis, the authors conclude that diverticulopexia is a safer surgical procedure than excision, giving less complications and a very good long-term functional result.

Results of long-term medical treatment of patients with arterial hypertension complicated by aortic dissection

The purpose of the study was to analyse results of ambulatory treatment of patients with arterial hypertension complicated by aortic dissection. Twenty patients (19 men, one woman), aged between 39 and 72 years, underwent full physical examination. In all cases the diagnosis of aortic dissection was confirmed by at least two different imaging methods (ultrasonography, digital subtractional angiography, computer tomography or nuclear magnetic resonance). During follow-up (3-75 months, mean 34.3 months), physical examination was performed every 6-8 weeks, chest radiograph was taken once a year. All patients controlled their blood pressure (BP) at home. According to the mean number of in-home BP measurements per month all patients were divided into two groups: group I good (n = 10) and group II bad compliers (n = 10) (28 +/- 30 vs 3 +/- 2 in-home BP measurements a month). Ten patients (6 in group I, 4 in group II) underwent 24 h automatic BP measurement examination. Blood samples were collected for serum cholesterol and uric acid measurements. All patients suffered from arterial hypertension and in five cases at least one parent suffered from this disease. Only three of 20 have never smoked cigarettes. Elevated serum cholesterol was observed in 10 (50%) cases and elevated uric acid in six (30%). Proximal (type A) aortic dissection (DeBakey classification type I and II) was found in 13 patients, distal aortic dissection (type B) in seven patients. All patients were treated with beta-blockers. In 75% of 20 cases three or more hypotensive drugs were used simultaneously to control BP. In the group I lower values of mean of maximal SBP (160 +/- 10 vs 177 +/- 7 mm Hg, P < 0.05) and lower mean circadian heart rate (58.6 +/- 7.5 vs 80.9 +/- 7.9 beats/min, P < 0.005) were observed. The most frequent complaints were intermittent claudication, 9 (45%); angina pectoris 8 (40%), other chest pain, 4 (20%). During follow-up period (3-75 months, mean 34.3 months) five of 20 patients (25%) died (all had proximal, type A dissection) and 15 of 20 patients (75%) are still alive. All deaths in group II were sudden, whereas the only one in group I was because of chronic renal insufficiency. Mortality rate in the two groups were 10% (one of 10) vs 40% (four of 10), respectively, in groups I and II.

IN CONCLUSION

patients who control their BP more often have the lower values as well as lower heart rate and therefore a better prognosis.

[Unusual clinical course of ruptured aortic aneurysms--reports of three cases]

Three cases of unexpected clinical course of ruptured aortic aneurysm have been presented in patients of their 7th decade life. All of them had arterial hypertension. Signs and symptoms on admission to hospital (dysphagia, chest and interscapular pain, hematemesis, abdominal pain, elevated body temperature and diminished exercise tolerance) were non-specific of aortic aneurysm, suggesting other disease. Dramatic clinical course with hypovolemic shock in two cases led to death. One of them refused surgery. In the third one, in spite of blood effusions to pleural cavity, pericardial sac and mediastinum, effective hypotensive therapy with a preservation of the slow heart rate and fluid evacuation from pericardial sac, gave the opportunity to perform elective surgery. Aortic dissection often presents an atypical course and when suspected, all available imaging technics including computed tomography and nuclear magnetic resonance must be used.

[Unusual clinical course of ruptured aortic aneurysms--report of three cases]

Three cases of unexpected clinical course of ruptured aortic aneurysm have been presented in patients of their 7th decade life. All of them had arterial hypertension. Signs and symptoms on admission to hospital (dysphagia, chest and interscapular pain, hematemesis, abdominal pain, elevated body temperature and diminished exercise tolerance) were non-specific of aortic aneurysm, suggesting other disease. Dramatic clinical course with hypovolemic shock in two cases led to death. One of them refused surgery. In the third one, in spite of blood effusions to pleural cavity, pericardial sac and mediastinum, effective hypotensive therapy with a preservation of the slow heart rate and fluid evacuation from pericardial sac, gave the opportunity to perform elective surgery. Aortic dissection often presents an atypical course and when suspected, all available imaging technics including computed tomography and nuclear magnetic resonance must be used.

[Left coronary artery-pulmonary artery fistula. Case report]

A case of a 45-year-old male with anterior descending branch of the left coronary artery fistula to the main pulmonary trunk is reported. The patient was admitted because of a retrosternal pain. ECG showed ST-elevation in leads V2-3. This was first episode of anginal symptoms. The authors suggest that the single episode of coronary pain may have been provoked by faintness (following alcohol consumption) in the mechanism of the steal syndrome or by coronary spasm. A fistula (on coronarography) was diagnosed (the coronary arteries showed no changes). The value of the shunt calculated via Flick's method was 1.1 l/min. Exercise test, 24-hour ECG recording as well as stress thallium scintigraphy did not reveal post-exertion ischemic changes. During a 17-month post hospitalization follow-up the patient reported no anginal symptoms. Because of the small shunt and asymptomatic follow-up no surgical treatment was recommended.

Cardiac chambers and their walls in cardiomyopathies as evaluated with CT

Thirty-two patients with cardiomyopathy, 25 with hypertrophic and 7 with dilated form were examined by cardiac catheterisation, left ventriculography, selective coronary angiography and ungated cardiac computed tomography. Diffuse hypertrophy, localized hypertrophy and dilated cardiomyopathy were diagnosed and assessed quantitatively based on CT linear, surface and volumetric parameters of cardiac morphology. Absolute septal thickness and left ventricular mass measured in CT image are the most discriminative attributes.