Assessing National Trends and Disparities in Ambulatory, Emergency Department, and Inpatient Visits for Inflammatory Bowel Disease in the United States (2005-2016).

BACKGROUND & AIMS: Patients with inflammatory bowel diseases (IBDs) require repeated health care encounters, although the focus of care differs when patients are seen in ambulatory, emergency department (ED), or inpatient settings. We examined contemporary trends and disparities in IBD-related health care visits. METHODS: We used data from the National Ambulatory Medical Care Survey, the Nationwide Emergency Department Sample, and the National Inpatient Sample to estimate the total number of annual IBD-related visits from 2005 through 2016. We performed logistic regression analyses to test temporal linear trends. Slope and differences in distributions of patient demographics were compared across time and treatment settings. RESULTS: From 2005 through 2016, approximately 2.2 million IBD-related ambulatory visits (95 CI, 1.9-2.5) occurred annually on average, increasing by 70.3% from the time period of 2005 to 2007 through the time period of 2008 to 2010, and decreasing by 19.8% from the time period of 2011 to 2013 through the time period of 2014 to 2016. An average of 115,934 IBD-related ED visits (95% CI, 113,758-118,111) and 89,111 IBD-related hospital discharges (95% CI, 87,416-90,807) occurred annually. Significant increases in the rate of IBD-related ED visits (3.2 visits/10,000 encounters; P < .0001) and hospital discharges (6.0 discharges/10,000 encounters; P < .0001) were observed from 2005 through 2016. The proportion of patients paying with private insurance decreased from 2005 through 2016, among all care settings. A greater proportion of young patients, patients with Crohn's disease, non-white patients, and patients with Medicare or Medicaid used hospital-based vs ambulatory services. CONCLUSIONS: In an analysis of data from 3 large databases, we found that although IBD-related ambulatory visits stabilized to decreased from 2005 through 2016, rates of ED use and admission to the hospital have continued to increase with changes in patient demographics, over time and among care settings.

Crohn's-like disease in a patient exposed to anti-Interleukin-17 blockade (Ixekizumab) for the treatment of chronic plaque psoriasis: a case report.

BACKGROUND: Plaque psoriasis and inflammatory bowel disease (IBD) are both chronic immune-mediated inflammatory diseases with an overlapping genetic profile and have been linked in epidemiological studies. Psoriasis and IBD share similar components in their inflammatory pathways and animal and human studies have suggested a potential role for targeting interleukin (IL)-17 with novel antibody therapies in the treatment of these diseases. These studies, while promising for psoriasis, have been associated with deterioration in patients with IBD. Post-hoc analyses of clinical trials involving Ixekizumab revealed adverse outcomes in a small cluster of patients with IBD, prompting recommendations to monitor this population with the use of this drug. CASE PRESENTATION: Forty-two year old Caucasian male with treatment-refractory chronic plaque psoriasis who developed new onset diarrheal illness and rectal bleeding following a 12 week induction period with Ixekizumab (anti-IL-17 neutralizing antibody). Colonoscopy revealed severe ulceration throughout the ascending and transcending colon. Histopathology, combined with endoscopic findings, led to a diagnosis of Crohn's-like colitis. The patient's anti-IL-17 medication was discontinued and endoscopic remission was induced with the use of corticosteroids, escalated anti-TNF therapy and eventually anti IL-12/23 neutralizing antibody (ustekinumab). CONCLUSION: Murine studies implicate IL-17 and the downstream effects of its inhibition, in the breakdown of the gut epithelial layer, the disruption of normal host immune responses and the propagation of intestinal inflammation. The increasing use of IL-17 inhibitors has led to reports of exacerbation and potential development of inflammatory bowel disease. While clinical trials have revealed clusters of new inflammatory bowel disease cases amongst psoriasis patients using an IL-17 inhibitor, there remains a lack of evidence to suggest a causal relationship. This is the first case report of de-novo severe Crohn's-like IBD in association with the use of Ixekizumab requiring rescue with escalated dosing of anti-TNF therapy and highlights the importance of close monitoring in patients being treated with IL-17 inhibitors, especially in those patients with known risk factors for inflammatory bowel disease.

The Evolution of Metastatic Colorectal Cancer Clinical Trials: Application of the ASCO Framework for Assessing Value.

Background: Phase III trials in metastatic colorectal cancer (mCRC) have collectively led to progressive advancements in patient outcomes over the past decades. This study characterizes the evolution of mCRC phase III trials through assessing the value of cancer therapy, as measured by the ASCO Value Framework. Methods: Phase III trial results of systemic therapy for mCRC published between 1980 and 2015 were identified, and their outcome, statistical significance, journal impact factor, and citation by the 2016 NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for CRC were recorded. For each trial, the net health benefit (NHB) score was calculated using the June 2015 (original) and May 2016 (revised) ASCO Value Framework: Advanced Disease. Results: There were 114 mCRC phase III trials eligible for calculation of the NHB score. Using the revised framework, the median NHB score was 4.6 (range, -30 to 43.5); 12% of trials received bonus points. Trials with statistically significant results had higher NHB scores compared with nonsignificant trials (median NHB score, 21.6 vs 2.9; P<.0001). Clinical trials cited in the NCCN Guidelines had higher NHB scores than those not cited (median score, 8.0 vs 0.3; P=.02). In multivariate linear regression analysis, the only significant predictor of high NHB score was statistically significant studies. Conclusions: The median NHB score for mCRC phase III trials was 4.6. Higher NHB scores are associated with statistically significant studies and are cited in the NCCN Guidelines, a surrogate for practice-changing trials. The 2016 ASCO Value Framework may not fully capture the benefits on an individual patient level.

Clinical Course and Treatment Implications of Combination Immune Checkpoint Inhibitor-Mediated Hepatitis: A Multicentre Cohort.

BACKGROUND: Immune-related adverse events can occur after treatment with immune checkpoint inhibitors (ICI), limiting treatment persistence. We aimed to evaluate the clinical course of ICI-mediated hepatitis (IMH) associated with combination ipilimumab and nivolumab treatment. METHODS: A retrospective cohort study including consecutive patients with metastatic melanoma treated with ipilimumab and nivolumab between 2013 and 2018 was conducted at two tertiary care centres. IMH was defined by the Common Terminology Criteria for Adverse Events (CTCAE). We determined the proportion of patients developing IMH, and compared the duration, treatment patterns and outcomes, stratified by hepatitis severity. Kaplan-Meier survival analysis was used to evaluate time to hepatitis resolution, and a linear mixed-effects model was used to compare longitudinal outcomes by treatment. RESULTS: A total of 63 patients were included. Thirty-two patients (51%) developed IMH (34% Grade 1-2, 66% Grade 3-4), at a median of 34 days (IQR 20 to 43.5 days) after the first dose. Baseline FIB4 index ≥1.45 was associated with IMH (OR 3.71 [95% CI: 1.03 to 13.38], P = 0.04). Ninety-four per cent (30/32) of patients had liver enzyme normalization after a median duration of 43 days (IQR 26 to 70 days). Corticosteroid use was not associated with faster IMH resolution or less ICI discontinuation. A total of 24 patients died during the study; no deaths were attributable to hepatitis-related complications. Fifty-three per cent (17/32) of patients resumed anti-PD-1 monotherapy and three patients developed IMH recurrence. CONCLUSIONS: Approximately half of the patients treated with combination ipilimumab and nivolumab developed IMH in this cohort. However, most patients experienced uncomplicated IMH resolution.

COVID-19 infection in liver transplant recipients: Clinical features and outcomes from a Canadian multicentre cohort.

BACKGROUND: Prior studies have assessed risk factors and clinical outcomes in liver transplant (LT) recipients infected with COVID-19 globally; however, there is a paucity of Canadian data. Our multicentre study aims to examine the characteristics and clinical outcomes of LT patients with COVID-19 infection in Canada. METHODS: Adult LT recipients with reverse transcription-polymerase chain reaction (RT-PCR) confirmed COVID-19, from Canadian tertiary care centres between March 2020 and June 2021 were included. RESULTS: A total of 49 patients with a history of LT and COVID-19 infection were identified. Twenty-nine patients (59%) were male, median time from LT was 66 months (IQR 1-128), and median age was 59 years (IQR 52-65). At COVID-19 diagnosis, the median alanine transaminase (ALT) was 37 U/L (IQR 21-41), aspartate aminotransferase (AST) U/L was 34 (IQR 20-37), alkaline phosphatase (ALP) U/L was 156 (IQR 88-156), total bilirubin was 11 µmol/L (IQR 7-14), and international normalized ratio (INR) was 1.1 (IQR 1.0-1.1). The majority of patients (86%) were on tacrolimus (monotherapy or combined with mycophenolate mofetil); median tacrolimus level at COVID-19 diagnosis was 5.3 µg/L (IQR 4.0-8.1). Immunosuppression was modified in eight (16%) patients post-infection. Eighteen patients (37%) required hospitalization, and three (6%) required intensive care unit (ICU) admission and mechanical ventilation. Four patients (8%) died from complications related to COVID-19 infection. On univariate analysis, neither age, sex, comorbidities, nor duration post-transplant were associated with risk of hospitalization or ICU admission. CONCLUSIONS: LT recipients with COVID-19 have high rates of hospitalization but fortunately have low rates of ICU admission and mortality in this national registry.

Relative hemilabilities of H2B(az)2 (az = pyrazolyl, dimethylpyrazolyl, methimazolyl) chelates in the complexes [M(η-C3H5)(CO)2{H2B(az)2}] (M = Mo, W).

The reactions of [M(η3-C3H5)Br(CO)2(NCMe)2] (M = Mo, W) or [Mo(η3-C3H5)Br(CO)2(PMe2Ph)2] with Na[H2B(mt)2] (mt = methimazolyl) affords the complexes [M(η3-C3H5)(CO)2{κ3-H,S,S'-H2B(mt)2}], the 3-centre, 2-electron B-H-M interaction of which was found to be inert with respect to opening under mild conditions, while more forcing conditions (heating with PMe2Ph) resulted in cleavage of the entire allyl and borate ligands to form [Mo(CO)3(PMe2Ph)3]. In contrast, the reaction of [Mo(η3-C3H5)Br(CO)2(NCMe)2] with Na[H2B(pz)2] affords either [Mo(η3-C3H5)(CO)2{κ3-H,N,N'-H2B(pz)2}] or (more likely) [Mo(η3-C3H5)(CO)2(NCMe){κ2-N,N'-H2B(pz)2}] which in turn reacts with phosphines to provide [[Mo(η3-C3H5)(CO)2(PPhR2){κ2-N,N'-H2B(pz)2}] (R = Me, Ph). The reactions discussed indicate the propensity for 3-centre, 2-electron B-H-Mo interactions increases in the order H2B(pz)2 < H2B(pz*)2 < H2B(mt)2 (pz* = 3,5-dimethypyrazolyl).

Hydrogenating an organometallic carbon chain: buten-yn-diyl (CH[double bond, length as m-dash]CHC[triple bond, length as m-dash]C) as a missing link.

The sequential reaction of [Ru(C[triple bond, length as m-dash]CC[triple bond, length as m-dash]CH)Cl(CO)2(PPh3)2] with [Ru(CO)2(PPh3)3], and N-chlorosuccinimide affords the binuclear tetracarbido complex [Ru2(µ-C[triple bond, length as m-dash]CC[triple bond, length as m-dash]C)Cl2(CO)4(PPh3)4]. This may be compared with the first example of a butenyndiyl bridged bimetallic complex [Ru2(µ-CH[double bond, length as m-dash]CHC[triple bond, length as m-dash]C)Cl2(CO)4(PPh3)4] which is obtained from the reaction of [Ru(C[triple bond, length as m-dash]CC[triple bond, length as m-dash]CH)Cl(CO)2(PPh3)2] with [RuHCl(CO)(PPh3)3] followed by carbonylation. Characterisational data are discussed with reference to constituent model complexes [Ru(C[triple bond, length as m-dash]CH)Cl(CO)2(PPh3)2] and [Ru(CH[double bond, length as m-dash]CH2)Cl(CO)2(PPh3)2] in addition to DFT analysis of the bonding in the complexes [Ru2(µ-L)Cl2(CO)4(PMe3)4] (L = C[triple bond, length as m-dash]C-C[triple bond, length as m-dash]C, CH[double bond, length as m-dash]CHC[triple bond, length as m-dash]C, CH[double bond, length as m-dash]CH-CH[double bond, length as m-dash]CH). A range of other tetracarbido complexes which may be prepared from [RuCl(C[triple bond, length as m-dash]CC[triple bond, length as m-dash]CH)(CO)2(PPh3)2] is also described and includes [RuAu(µ-C4)Cl(CO)3(PPh3)3], [RuIr(µ-C4)Cl(CO)3(PPh3)4], [RuIr(µ-C4)H(NCMe)(CO)3(PPh3)4]BF4, [RuIr(µ-C4)Cl(η2-O2)(CO)3(PPh3)4], [Ru2Hg(µ-C4)2Cl2(CO)4(PPh3)4], [Ru2Pt(µ-C4)2Cl2(CO)4(PPh3)6] and [Ru2(µ-C4)HCl(CO)4(PPh3)4].

High Thermal and Electrical Conductivity of Template Fabricated P3HT/MWCNT Composite Nanofibers.

Nanoporous alumina membranes are filled with multiwalled carbon nanotubes (MWCNTs) and then poly(3-hexylthiophene-2,5-diyl) (P3HT) melt, resulting in nanofibers with nanoconfinement induced coalignment of both MWCNT and polymer chains. The simple sonication process proposed here can achieve vertically aligned arrays of P3HT/MWCNT composite nanofibers with 3 wt % to 55 wt % MWCNT content, measured using thermogravimetric methods. Electrical and thermal transport in the composite nanofibers improves drastically with increasing carbon nanotube content where nanofiber thermal conductivity peaks at 4.7 ± 1.1 Wm(-1)K(-1) for 24 wt % MWCNT and electrical percolation occurs once 20 wt % MWCNT content is surpassed. This is the first report of the thermal conductivity of template fabricated composite nanofibers and the first proposed processing technique to enable template fabrication of composite nanofibers with high filler content and long aspect ratio fillers, where enhanced properties can also be realized on the macroscale due to vertical alignment of the nanofibers. These materials are interesting for thermal management applications due to their high thermal conductivity and temperature stability.

Novel poly(methimazolyl)borate complexes of niobium(V) and tantalum(V).

The reactions of [MCl4(eta-C5H5)](M = Nb, Ta) with Ph3Sn{HB(mt)3} (mt = methimazolyl) provide structurally characterised complexes of the new chlorobis(methimazolyl)borate ligand, [MCl3(eta-C5H5){kappa2-S,S'-HClB(mt)2}].

Poly(3-hexylthiophene) nanotube array surfaces with tunable wetting and contact thermal energy transport.

Solution casting using a sacrificial template is a simple technique to fabricate vertical arrays of polymer nanotubes. However, because of their close proximity and high aspect ratios, large capillary forces cause nanotubes to cluster as the array dries; researchers often use special drying techniques to avoid this clustering. Here, we exploit the clustering of regioregular poly(3-hexylthiophene) (rr-P3HT) nanotubes in a unique template etching process to create surfaces that exhibit tunable wetting and contact thermal energy transport. Vertical arrays of rr-P3HT nanotubes are cast from solution in nanoscale alumina templates, and a solution etching process is used to partially release the nanotubes from the template. The clustering of rr-P3HT nanotube tips upon template etching produces hierarchical surface structuring with a distinct pattern of interconnected ridges, and the spacing between the ridges increases with increased template etch times. These changes in morphology cause the water contact angle to increase from 141° to 168° as the etch time is increased from 4 to 12 min. When assembled into an interface, the morphological changes cause the thermal contact resistance of the vertical rr-P3HT nanotube arrays to increase linearly at a rate of approximately 6 mm(2)·K/W per 2 min etch interval (after 6 min of etching is surpassed). The effective thermal conductivity of the rr-P3HT nanotube arrays is 1 ± 0.2 W/mK independent of the etch time, which is approximately 5 times higher than the bulk rr-P3HT film value.

UV and hydrogen peroxide treatment restores changes in innate immunity caused by exposure of fish to reuse water.

The purpose of this study was to assess the innate immunity of goldfish exposed to reuse water, and UV/H2O2-treated reuse water, using a real-time flow-through exposure system. The reuse water generated by ultrafiltration of finished wastewater from the municipal wastewater treatment plant was analyzed for the presence of a panel of 20 herbicides/fungicides and 46 pharmaceuticals and personal care products (PPCP). There was a seasonal variation in the profile and concentrations of xenobiotics in reuse water with lowest levels occurring in the summer. The innate immunity parameters assessed were cytokine (IFNγ, IL-1ß, IL-10, TNFα2), and cytokine receptor (TNFR1, TNFR2, IFNGR1, IFNGR2) gene expression, and phagocytosis of kidney leukocyte subpopulations. Assessment of innate immunity parameters was done after acute (7 days) and sub chronic (30 and 60 days) exposure to reuse water, UV/H2O2-treated reuse water, and activated carbon-treated reuse water (ACT; control), during spring, summer and fall of 2012. Temporal (acute versus sub chronic) as well as seasonal differences in innate immunity of fish exposed to reuse water were observed. The acute exposure of fish to reuse water caused significant down-regulation in cytokine gene expression in different organs of fish (kidney, spleen, liver) and phagocytic ability of different kidney leukocyte subpopulations. The immune gene expression and phagocytosis of kidney leukocytes of fish returned to ACT control levels after sub chronic exposure suggesting that fish have habituated to the reuse water exposure. The changes in gene expression after acute exposure were related to variations in the profile of xenobiotics in reuse water during different seasons. The efficiency of xenobiotic removal using UV/H2O2 ranged between 1.6 and 100% indicating that treatment of reuse water using high dose UV/H2O2 was only partially effective in removing the xenobiotics, as assessed by both chemical analyses and measurement of innate immune responsiveness of the fish. Furthermore, exposure of fish to reuse water and UV/H2O2-treated reuse water generated in the spring and fall caused greater changes in innate immunity after acute exposure, compared to fish exposed to ACT reuse water, indicating that the remediation of reuse water, should be considered in order to protect aquatic and public health.

Syntheses, Electrochemical, Linear Optical, and Cubic Nonlinear Optical Properties of Ruthenium-Alkynyl-Functionalized Oligo(phenylenevinylene) Stars.

The syntheses of trans-[Ru(C≡CC6 H4 -4-CHO)(C≡CC6 H4 -4-R)(dppe)2 ] (R=H (9 a), NO2 (9 b), CHO (9 c), C≡CC6 H3 -3,5-Et2 (9 d), (E)-CHCHC6 H4 -4-tBu (9 e); dppe=1,2-bis(diphenylphosphino)ethane), trans-[Ru(C≡CC6 H4 -4-R)Cl(dppe)2 ] (R=C≡CC6 H3 -3,5-Et2 (11 a), (E)-CHCHC6 H4 -4-tBu (11 b), (E)-CHCHC6 H4 -4-NO2 (11 c)), 1,2,4,5-{trans-[(dppe)2 (RC6 H4 C≡C)Ru{C≡CC6 H4 -4-(E)-CHCH}]}4 C6 H2 (R=H (14 a), C≡CC6 H3 -3,5-Et2 (14 b), (E)-CHCHC6 H4 -4-tBu (14 c)), 1-I-3,5-{trans-[(L2 )2 (R)Ru{C≡CC6 H4 -4-(E)-CHCH}]}2 C6 H3 (L2 =1,1-bis(diphenylphosphino)methane (dppm)), R=Cl (15 a); L2 =dppe, R=C≡CPh (15 b), R=C≡CC6 H4 -4-NO2 (15 c)), 1-Me3 SiC≡C-3,5-{trans-[(L2 )2 (R)Ru{C≡CC6 H4 -4-(E)-CHCH}]}2 C6 H3 (L2 =dppm, R=Cl (16 a); L2 =dppe, R=C≡CPh (16 b)), 1-HC≡C-3,5-{trans-[(dppe)2 (R)Ru{C≡CC6 H4 -4-(E)-CHCH}]}2 C6 H3 (R=Cl (17 a), R=C≡CPh (17 b)), and 1,3,5-{trans-[(dppe)2 (3,5-R2 -C6 H3 C≡C)Ru{C≡CC6 H4 -4-(E)-CHCH}]}3 C6 H3 (R=(E)-CHCHC6 H4 -4-C≡C-trans-[Ru(C≡CPh)(dppe)2 ] (18)) are reported together with those of the precursor alkynes 1-RC≡C-3,5-Et2 C6 H3 (R=SiMe3 (2), H (3), C6 H4 -4-C≡CSiMe3 (5), C6 H4 -4-C≡CH (6)). The identities of 9 c, 9 d, 9 e, 11 a, and trans-[Ru{C≡CC6 H4 -4-(E)-CHCHC6 H4 -4-tBu}2 (dppe)2 ] (12 and 12') were confirmed by single-crystal X-ray diffraction studies. The electrochemical properties of 9 a-e, 11 a-b, 14 a-c, 15 a-c, 16 b, 17 a, 17 b, and 18 were assessed by cyclic voltammetry; the studies reveal that potentials for the fully/quasi-reversible metal-centered oxidation processes decrease upon introduction of solubilizing alkyl substituents and increase upon increasing acceptor substituent strength; other structural variations have little impact. UV/Vis-NIR spectroscopic studies on these complexes reveal lowest-energy metal-ligand charge transfer (MLCT) bands that redshift upon increasing the acceptor substituent strength, blueshift on alkyl incorporation, and gain in intensity on progression from linear to star complexes. Low-temperature UV/Vis-NIR spectroelectrochemical studies of 14 a-c show the appearance of an intense low-energy band at 7400-7900 cm-1 that is redshifted upon π-system lengthening and alkyl substituent incorporation. The cubic nonlinear optical properties of 9 d, 9 e, 14 a-c, 15 a-c, 16 b, 17 a, b, and 18 were assayed by femtosecond Z-scan studies at benchmark wavelengths (750 and 800 nm) in the near-IR region, with nonlinearity increasing upon nitro incorporation; the values for the E-ene-linked dendrimers in these studies are much larger than yne-linked analogues. Compounds 9 d, 9 e, 14 a-c, and 18 were further examined by broad-spectral-range femtosecond Z-scan studies; the cruciform complexes have appreciable multiphoton absorption cross-sections, with maximal values close to two and three times the wavelength of the linear optical absorption maxima.

Caveats for poly(methimazolyl)borate chemistry: the novel inorganic heterocycles [H2C(mt)2BR2]Cl (mt = methimazolyl; BR2 = BH2, BH(mt), 9-BBN).

Whilst frequently used for reactions of poly(methimazolyl)borates, dichloromethane is not an innocent solvent, but rather slowly forms heterocyclic salts [H(2)C(mt)(2)BR(2)]Cl, three examples of which (BR(2) = BH(2), BH(mt), 9-borabicyclononyl) have been structurally characterised to confirm the unprecedented B(NCS)(2)C connectivity.

A soluble form of the CSF-1 receptor contributes to the inhibition of inflammation in a teleost fish.

We previously reported on the identification of a novel soluble form of the CSF-1 receptor (sCSF-1R) in goldfish that induced dose-dependent down-regulation of macrophage proliferation. Herein, we report that sCSF-1R has a role beyond macrophage development, which extends into the control of cellular antimicrobial inflammatory responses in this lower vertebrate. Using an in vivo model of self-resolving peritonitis coupled to in vitro characterization of sCSF-1R activity, we show that sCSF-1R plays a role in the inhibition of inflammation which follows an initial acute phase of innate antimicrobial responses within an inflammatory site. In vitro, mature goldfish primary kidney macrophages but not monocytes up-regulated sCSF-1R expression upon direct contact with apoptotic cells. In vivo, sCSF-1R expression coincided with an increase in macrophage numbers that resulted from administration of apoptotic cells into the goldfish peritoneal cavity. This contrasted the decrease in sCSF-1R expression during zymosan-induced inflammatory responses in vivo. Subsequent experiments showed an anti-inflammatory effect for sCSF-1R. Leukocyte infiltration and ROS production decreased in a dose-dependent manner compared to zymosan-stimulated controls upon addition of increasing doses of recombinant sCSF-1R. Among others, sCSF-1R may contribute to the dual role that phagocytic macrophages play in the induction and regulation of inflammation. Overall, our results provide new insights into ancient mechanisms of inflammation control and, in particular, the evolutionary origins of the CSF-1 immune regulatory axis.

Minimising reversion, using seawater and magnesium chloride, caused by the dissolution of tricalcium aluminate hexahydrate.

The increase in pH and aluminium concentration after the neutralisation of bauxite refinery residues is commonly known as reversion. This investigation reports the extent of reversion in synthetic supernatant liquor and possible methods to reduce reversion. This work is based on bauxite refinery residues produced from alumina refineries, where reversion is a real life situation in neutralised refinery residues. Tricalcium aluminate hexahydrate, a common phase in bauxite refinery residues, has been found to cause reversion. It has been established that reductions in both pH and aluminium from the seawater neutralisation process are due to the formation of 'Bayer' hydrotalcite Mg(7)Al(2)(OH)(18)(CO(3)(2-),SO(4)(2-))·xH(2)O. This is the primary mechanism involved in the removal of aluminium from solution. Increasing the volume of seawater used for the neutralisation process minimises the extent of reversion for both synthetic supernatant liquor and red mud slurry. The addition of MgCl(2)·6H(2)O also showed a reduction in reversion and confirmed that the decrease in aluminium and hydroxyl ions is due to the formation of Bayer hydrotalcite and not simply a dilution effect.

Ru and Os complexes containing a P,N-donor heterotopic ligand: the effect of solvent on stereochemistry.

Ruthenium and osmium complexes of the general formula MCl 2(PyP) 2 (where PyP is the P,N- donor ligand 1-(2-diphenylphosphinoethyl)pyrazole) were synthesized from MCl 2(PPh 3) 3 (where M = Ru or Os). Three of the five possible stereoisomers of RuCl 2(PyP) 2 were synthesized and characterized in solution by multinuclear NMR spectroscopy, and the structure of these in the solid state was determined by X-ray crystallography. Two of the analogous Os isomers were also synthesized. It was found that different solvents induced isomerization between these stereoisomers, indicating either lability of the chloride anion or hemilability of the PyP ligand. Bimetallic complexes of the general formula [Ru(mu-Cl)(PyP) 2] 2[X] 2 were synthesized from chloride abstraction from RuCl 2(PyP) 2 using either silver (X = OSO 2CF 3, BF 4) or sodium (X = BPh 4) salts. The osmium analogue of the Ru bimetallic complexes, [Os(mu-Cl)(PyP) 2] 2[BPh 4] 2, was also synthesized. Solid-state structures were obtained using X-ray crystallography for the osmium bimetallic complex and the ruthenium bimetallic complex where X = OSO 2CF 3. The hemilability of PyP was demonstrated through the synthesis of RuCl 2(CO)(kappa (1)- P-PyP)(kappa (2)- P, N-PyP), which contains one pendant PyP ligand, bound through the P-donor atom.

A homoleptic hydrotris(methimazolyl)borate complex of titanium.

The reaction of [Ti(2)(micro-Cl)(2)(thf)(2)(eta-C(8)H(8))(2)] with Na[HB(mt)(3)] (mt = methimazolyl) provides the unusual salt [Ti{HB(mt)(3)}(2)][TiCl(4)(thf)(2)], the cation of which features homoleptic Ti(III)S(6) coordination.

Dihydrobis(methimazolyl)borate and methimazolyl complexes of titanium.

The first poly(methimazolyl)borato complex of group 4, [Ti([double bond, length as m-dash]NCMe(3)){H(2)B(mt)(2)}(2)](mt = methimazolyl), results from the reaction of Na[H(2)B(mt)(2)] with [Ti([double bond, length as m-dash]NCMe(3))Cl(2)(py)(3)] and features both kappa(2)-S,S' and kappa(3)-H,S,S' coordination of H(2)B(mt)(2) ligands coincident within the same molecule.

Niobium and tantalum tris(methimazolyl)borate complexes [M(=NC6H3iPr2-2,6)Cl2{HB(mt)3}] (M = Nb, Ta; mt = methimazolyl).

The first early transition metal tris(methimazolyl)borate com-plexes [M(=NR)Cl2{HB(mt)3}] (M = Nb, Ta; R = C6H3(i)Pr(2)-2,6; mt = methimazolyl) have been obtained from the reactions of [Nb(=NR)Cl3(DME)] or [Ta(=NR)Cl3(THF)2] (DME = dimethyl ether; THF = tetrahydrofuran) with Na[HB(mt)3] and structurally characterized, illustrating that the HB(mt)3 ligand can indeed be compatible with "hard" metals in high oxidation states.