The clinical course of symptoms during wait time for lumbar spinal stenosis surgery and its effect on postoperative outcome: a retrospective cohort study

BACKGROUND CONTEXT

Wait time for surgeries can be lengthy and its effect on postoperative outcome remains largely unknown.

PURPOSE

We evaluated the effect of wait time on postoperative outcome and on clinical course while awaiting surgery for lumbar spinal stenosis.

STUDY DESIGN/SETTING

This was a retrospective cohort study.

PATIENT SAMPLE

A convenience sample (n=134) from prospective longitudinal studies that provided preoperative Oswestry Disability Index (ODI) data at two different time points and follow-up of ≥12 months.

METHODS

Wait time was the period between the initial consultation and immediately preoperatively.

OUTCOME MEASURES

The primary outcome was the ODI minimal clinically important difference (MCID) (<30% vs ≥30% improvement) at 1 year.

RESULTS

The median wait time was 5.9 (interquartile range (IQR) 8.2) months and postoperative follow-up was 19.2 (IQR 8.1) months. Wait time was not associated with absolute postoperative change in ODI scores, but patients with wait times <12 months were significantly more likely to reach the ODI MCID at last follow-up (66 (73.3%) for <12 months versus 13 (46.4%) for ≥12 months, p=.008; odds ratio=0.29 (95% confidence interval 0.12-0.75), p=.011). During wait time, there was no difference in patients deteriorating above the MCID for each time point (10 [9.7%] versus 5 [16.1%], p=.320).

CONCLUSIONS

Longer wait times did not negatively influence postoperative outcome in patients with lumbar spinal stenosis using absolute values, but may impact individual patients' ability to achieve MCID. Patient-reported pain-related disability from the initial surgical consultation to surgery is relatively stable in most patients for at least 6 to 12 months.

Hospital spending and length of stay attributable to perioperative adverse events for inpatient hip, knee, and spine surgery: a retrospective cohort study

BACKGROUND

The incremental hospital cost and length of stay (LOS) associated with adverse events (AEs) has not been well characterized for planned and unplanned inpatient spine, hip, and knee surgeries.

METHODS

Retrospective cohort study of hip, knee, and spine surgeries at an academic hospital in 2011-2012. Adverse events were prospectively collected for 3,063 inpatient cases using the Orthopaedic Surgical AdVerse Event Severity (OrthoSAVES) reporting tool. Case costs were retrospectively obtained and inflated to equivalent 2021 CAD values. Propensity score methodology was used to assess the cost and LOS attributable to AEs, controlling for a variety of patient and procedure factors.

RESULTS

The sample was 55% female and average age was 64; 79% of admissions were planned. 30% of cases had one or more AEs (82% had low-severity AEs at worst). The incremental cost and LOS attributable to AEs were $8,500 (95% confidence interval [CI]: 5100-11,800) and 4.7 days (95% CI: 3.4-5.9) per admission. This corresponded to a cumulative $7.8 M (14% of total cohort cost) and 4,290 bed-days (19% of cohort bed-days) attributable to AEs. Incremental estimates varied substantially by (1) admission type (planned: $4,700/2.4 days; unplanned: $20,700/11.5 days), (2) AE severity (low: $4,000/3.1 days; high: $29,500/11.9 days), and (3) anatomical region (spine: $19,800/9 days; hip: $4,900/3.8 days; knee: $1,900/1.5 days). Despite only 21% of admissions being unplanned, adverse events in these admissions cumulatively accounted for 59% of costs and 62% of bed-days attributable to AEs.

CONCLUSIONS

This study comprehensively demonstrates the considerable cost and LOS attributable to AEs in orthopaedic and spine admissions. In particular, the incremental cost and LOS attributable to AEs per admission were almost five times as high among unplanned admissions compared to planned admissions. Mitigation strategies focused on unplanned surgeries may result in significant quality improvement and cost savings in the healthcare system.

The Prominence of Facilitator π-Holes: The Classic N←N Pnictogen Bonding in Nitrobenzene-Ammonia Dimer with its Structural Elucidation and Experimental Characterization at Low Temperatures

The nitrogen of nitro group is a paradigmatic pnictogen due the presence of a π-hole and a number of studies have been performed recently on prototypical nitromethane (NM). Homodimers and heterodimers of NM are sustained by π-hole driven pnictogen bonds hosted by nitrogen. To understand the effect of substitution on this π-hole and thus the pnictogen bond, heterodimers of nitrobenzene (NB; phenyl substitution in place of methyl) with ammonia (AM) have been probed, as a test case, using matrix isolation infrared spectroscopy and ab initio computations. Of the four structures optimized on the potential energy surface the energetically dominant global minimum, stabilized by π-hole driven O=N←N pnictogen bonding with co-operative N-H←O hydrogen bonding, was experimentally identified at low temperatures. A comparison of the pnictogen bonding of NB-AM dimers with NM counterpart (NM-AM dimers) divulged the dominance of electrostatic origin of pnictogen bonding in both the class of dimers. The reduced strength of pnictogen bonding in NB-AM dimers in comparison to NM-AM dimers was discerned, which has been established to be a consequence of the reduced electrostatic potential at the π-hole of NB relative to that in NM. The strength of π-hole driven pnictogen bond was directly correlated with the binding energy and the infrared shifts in the signature vibrational bands of the NB, NM and AM submolecules due to dimerization under matrix isolated conditions at low temperatures.

Enhanced luminescence of tris(carboxylato)uranyl(VI) complexes and energy transfer to Eu(III): a combined spectroscopic and theoretical investigation

Complex formation between uranyl and carboxylate ligands (benzoate, nicotinate and isonicotinate) has been studied extensively by absorption and luminescence spectroscopy in acetonitrile medium. Experimental data had indicated the existence of stable and enhanced luminescent tris(carboxylato) uranyl(VI) complexes i.e. [UO₂(L)₃]^- with D_3h symmetry. The high luminescence of these complexes was due to the sensitization of the O_yl → U ligand to metal charge transfer (LMCT) emission by extremely intense equatorial (carboxylate ligands) LMCT bands. The variation in the experimentally observed parameters such as intensity of equatorial LMCT bands, luminescence lifetimes, quantum yields and structural parameters among tris(carboxylato) uranyl(VI) complexes are affirmed by quantum chemical calculations using density functional theory and the computational results are found to be in good agreement with experimental findings. Interestingly, in a very dilute mixture of [UO₂(L)₃]^- and Eu(III), energy transfer from uranyl to Eu(III) is observed and it leads to the detection of europium at trace levels. This is an intriguing observation as none of the previous studies have reported such a low level of detection limit of Eu(III) by means of energy transfer from any metal.

The potential for diversion of prescribed opioids among orthopaedic patients: Results of an anonymous patient survey

INTRODUCTION

Diversion of prescription opioid medication is a contributor to the opioid epidemic. Safe handling practices can reduce the risk of diversion. We aimed to understand: 1) if orthopaedic patients received instructions on how to safely handle opioids, 2) their typical storage/disposal practices, and 3) their willingness to participate in an opioid disposal program (ODP).

METHODS

Cross-sectional study of adult orthopaedic patients who completed an anonymous survey on current or past prescription opioid use, instruction on handling, storage and disposal practices, presence of children in the household, and willingness to participate in an ODP. Frequencies and percentages of responses were computed, both overall and stratified by possession of unused opioids.

RESULTS

569 respondents who reported either current or past prescription opioid use were analyzed. 44% reported receiving storage instructions and 56% reported receiving disposal instructions from a health care provider. Many respondents indicated unsafe handling practices: possessing unused opioids (34%), using unsafe storage methods (90%), and using unsafe disposal methods (34%). Respondents with unused opioids were less likely to report receiving handling instructions or using safe handling methods, and 47% of this group reported having minors or young adults in the household. Respondents who received storage and disposal instructions were more likely to report safe storage and disposal methods. Seventy-four percent of respondents reported that they would participate in an ODP.

CONCLUSION

While many orthopaedic patients report inadequate education on safe opioid handling and using unsafe handling practices, findings suggest targeted education is associated with better behaviours. However, patients are willing to safely dispose of unused medication if provided a convenient option. These findings suggest a need to address patient knowledge and behavior regarding opioid handling to reduce the risk of opioid diversion.

Nd(III) hypersensitive peak as an optical absorption probe for determining nitric acid in aqueous solution: An application to aqueous raffinate solutions in nuclear reprocessing

A new method using Nd(III) absorption peak as a probe is described for the measurement of nitric acid concentration in aqueous solution. The hypersensitive peak of Nd(III) at 575.1 nm shows a substantial enhancement in the absorbance in comparison to other absorption peaks with increasing nitric acid concentration. The integrated area and absorbance of this hypersensitive peak show a linear dependency over a large dynamic range of 0.5-15.5 M of nitric acid. A methodology for the correction of spectral interference to the probing absorption peak of Nd(III) is also reported. The method is applied for the measurement of nitric acid in synthetic high level liquid waste solution and shown to be comparable to that obtained by titrimetric method. The present method can be easily adopted for the measurement of nitric acid concentration in aqueous raffinate solutions of nuclear reprocessing streams.

Bridging the Gap between Symptom Onset and Diagnosis in Axial Spondyloarthritis

OBJECTIVE

To evaluate a stratified screening process for early identification of axial spondyloarthritis (axSpA) considering: 1) wait times from primary care to rheumatology screen; 2) incremental precision and accuracy from primary care to rheumatology screen; and 3) diagnostic delay.

METHODS

Adults with low back pain (LBP) attending primary care LBP clinics prospectively underwent a primary standardized clinical screen. Patients with LBP >3 months and onset age <50 years were referred for a comprehensive secondary screen by a physiotherapist with advanced rheumatology training. At secondary screening, patients with inflammatory features were deemed to have a low, medium, or high risk of axSpA vs. no risk. Precision and accuracy of this screening strata were measured against a rheumatologist with axSpA expertise.

RESULTS

In all, 405 patients underwent primary and secondary screening. Mean age was 36.9 years (±9.9); 55% were female. HLA-B27 was present in 14.4%. Median wait time from primary to secondary screen was 15 days. AxSpA risk assignment by rheumatologist was: 64.9% (none or low risk axSpA) and 35.1% (medium or high risk axSpA). The best combination of sensitivity (68%), specificity (90%), positive (80%) and negative (84%) predictive values was evident with the secondary screen. 15.6% of patients received a final diagnosis of axSpA. Median LBP duration from onset to diagnosis was: 2 years (non-radiographic axSpA) and 7 years (ankylosing spondylitis).

CONCLUSION

A stratified interprofessional screening process can facilitate rapid diagnosis of persistent LBP, with high precision and accuracy, in patients with axSpA.

What Goes Bump in the Night: An Evaluation of Emergency Department Visits Following Total Joint Arthroplasty

BACKGROUND

Interest in postoperative healthcare utilization has increased following the implementation of episode-of-care funding for elective orthopedic surgery. Most efforts have focused on readmission; however, little has been reported on emergency department (ED) presentation. We analyzed elective, primary total hip or knee arthroplasty (THA and TKA) cases to determine the rate, reasons, risk factors, timing, and hospital cost associated with 30-day ED presentations.

METHODS

An observational study of patients who underwent primary, elective TKA and THA between January 1, 2016, and December 31, 2017, was performed. The primary outcome was an ED visit within 30-days of the index operation. Secondary outcomes included reasons, risk factors, timing, and hospital cost of ED visits. A multivariable logistic regression was undertaken to determine patient factors associated with ED presentation.

RESULTS

Overall, 1690 patients were included, of which 9.2% presented to the ED within 30-days of surgery. Approximately two-thirds of the visits were after-hours, and most were discharged home without readmission (81.4%). The most commonly reported reasons were wound concerns (30.1%) and pain (20.5%). Older age (OR 1.1, P = .03) and preoperative dyspnea (OR 2.1, P < .001) increased the odds of ED visits. The mean cost of an ED visit was significantly greater after-hours (P = .015).

CONCLUSION

Overall, 1 in 10 patients undergoing TKA/THA presented to the ED within 30-days of surgery, of which over 80% were not readmitted, and most occurred after-hours where cost is greatest. Our observations suggest ED visits following TKA/THA are common, and most are likely preventable. Future efforts should focus on developing interventions to reduce these visits.

Nitrogen as a pnicogen?: evidence for π-hole driven novel pnicogen bonding interactions in nitromethane-ammonia aggregates using matrix isolation infrared spectroscopy and ab initio computations

The role of nitrogen, the first member of the pnicogen group, as an electron donor in hypervalent non-covalent interactions has been established long ago, while observation of its electron accepting capability is still elusive experimentally, and remains quite intriguing, conceptually. In the light of minimal computational exploration of this novel class of pnicogen bonding so far, the present work provides experimental proof with unprecedented clarity, for the existence of N(acceptor)N(donor) interaction using the model nitromethane (NM) molecule with ammonia (AM) as a Lewis base in NM-AM aggregates. The NM-AM dimer, in which the nitrogen atom of NM (as a unique pnicogen) accepts electrons from AM (the traditional electron donor), was synthesized at low temperatures under isolated conditions within inert gas matrixes and was characterized using infrared spectroscopy. The experimental generation of the NM-AM dimer stabilized via NN interaction has strong corroboration from ab initio calculations. Furthermore, confirmation regarding the directional prevalence of this NN interaction over C-HN and N-HO hydrogen bonding is elucidated quantitatively by quantum theory of atoms in molecules (QTAIM), electrostatic potential mapping (ESP), natural bond orbital (NBO), non-covalent interaction (NCI) and energy decomposition (ED) analyses. The present study also allows the extension of σ-hole/π-hole driven interactions to the atoms of the second period, in spite of their low polarizability.

Zinc finger protein-440 promotes cartilage degenerative mechanisms in human facet and knee osteoarthritis chondrocytes

OBJECTIVES

To investigate the role of zinc finger protein 440 (ZNF440) in the pathophysiology of cartilage degeneration during facet joint (FJ) and knee osteoarthritis (OA).

METHODS

Expression of ZNF440 in FJ and knee cartilage was determined by immunohistochemistry, quantitative (q)PCR, and Western blotting (WB). Human chondrocytes isolated from FJ and knee OA cartilage were cultured and transduced with ZNF440 or control plasmid, or transfected with ZNF440 or control small interfering RNA (siRNA), with/without interleukin (IL)-1β. Gene and protein levels of catabolic, anabolic and apoptosis markers were determined by qPCR or WB, respectively. In silico analyses were performed to determine compounds with potential to inhibit expression of ZNF440.

RESULTS

ZNF440 expression was increased in both FJ and knee OA cartilage compared to control cartilage. In vitro, overexpression of ZNF440 significantly increased expression of MMP13 and PARP p85, and decreased expression of COL2A1. Knockdown of ZNF440 with siRNA partially reversed the catabolic and cell death phenotype of human knee and FJ OA chondrocytes stimulated with IL-1β. In silico analysis followed by validation assays identified scriptaid as a compound with potential to downregulate the expression of ZNF440. Validation experiments showed that scriptaid reduced the expression of ZNF440 in OA chondrocytes and concomitantly reduced the expression of MMP13 and PARP p85 in human knee OA chondrocytes overexpressing ZNF440.

CONCLUSIONS

The expression of ZNF440 is significantly increased in human FJ and knee OA cartilage and may regulate cartilage degenerative mechanisms. Furthermore, scriptaid reduces the expression of ZNF440 and inhibits its destructive effects in OA chondrocytes.

Conformational topography of tris(2-methylbutyl) phosphate and the influence of methyl branching at the non-hyperconjugative carbon on the conformational landscape: insights from matrix isolation infrared spectroscopy and DFT computations

The branching of a methyl group in a linear chain has a profound influence on the conformational morphology as it wields a strong control in reducing a large number of conformations. To unravel the effect of branching on the second non-hyperconjugative carbon atom on the conformational landscape, the conformations of tris(2-methylbutyl)phosphate (T2MBP) were studied using Density Functional Theory (DFT) computations and matrix isolation infrared spectroscopy. Experimentally, T2MBP along with N₂/Ar/Kr/Xe gases was effusively expanded and deposited at a low temperature of 12 K, which was subsequently probed using infrared spectroscopy. The computations of all the conformations were accomplished using the B3LYP level of theory with the 6-311++G(d,p) basis set. A dimethyl(2-methylbutyl) phosphate (DM2MBP) prototype, a molecule containing a single 2-methylbutyl moiety, was examined for its conformations. Computations predicted 18 and 9 conformations each for the 'gauche' and 'trans' families, respectively, in which the third branched carbon completely influences the orientation of the fourth carbon, which simplifies the conformational problem of DM2MBP. Of the 18 and 9 bunches each in the 'gauche' and 'trans' families, only 7 and 3 conformations, respectively, became energetically important, which when extrapolated to T2MBP resulted in 343 and 147 conformational possibilities. The factor of degeneracy further reduced these numbers and a total of 168 conformations effectively contribute to the conformational composition of T2MBP in the gas phase. The role of stereo electronic and steric factors prevalent in the conformational clusters of T2MBP was unravelled respectively using natural bond orbital and non-covalent interaction analyses.

Unusual blue to red shifting of C-H stretching frequency of CHCl3 in co-operatively P⋯Cl phosphorus bonded POCl3-CHCl3 heterodimers at low temperature inert matrixes

Heterodimers of POCl₃-CHCl₃ were generated in Ne, Ar, and Kr matrixes at low temperatures and were studied using infrared spectroscopy. The remarkable role of co-operative pentavalent phosphorus bonding in the stabilization of the structure dictated by hydrogen bonding is deciphered. The complete potential energy surface of the heterodimer was scanned by ab initio and density functional theory computational methodologies. The hydrogen bond between the phosphoryl oxygen of POCl₃ and C-H group of CHCl₃ in heterodimers induces a blue-shift in the C-H stretching frequency within the Ne matrix. However, in Ar and Kr matrixes, the C-H stretching frequency is exceptionally red-shifted in stark contrast with Ne. The plausibility of the Fermi resonance by the C-H stretching vibrational mode with higher order modes in the heterodimers has been eliminated as a possible cause within Ar and Kr matrixes by isotopic substitution (CDCl₃) experiments. To evaluate the influence of matrixes as a possible cause of red-shift, self-consistent Iso-density polarized continuum reaction field model was applied. This conveyed the important role of the dielectric matrixes in inducing the fascinating vibrational shift from blue (Ne) to red (Ar and Kr) due to the matrix specific transmutation of the POCl₃-CHCl₃ structure. The heterodimer produced in the Ne matrix possesses a cyclic structure stabilized by hydrogen bonding with co-operative phosphorus bonding, while in Ar and Kr the generation of an acyclic open structure stabilized solely by hydrogen bonding is promoted. Compelling justification regarding the dispersion force based influence of matrix environments in addition to the well-known dielectric influence is presented.

Dominance of unique Pπ phosphorus bonding with π donors: evidence using matrix isolation infrared spectroscopy and computational methodology

Albeit the first account of hypervalentπ interactions has been reported with halogenπ interactions, the feasibility of their extension to other hypervalent atoms as possible Lewis acids is still open. In this work, the role of phosphorus as an acceptor from the π electron cloud (Pπ pnicogen or phosphorus bonding) in PCl3-C2H2 and PCl3-C2H4 heterodimers is explored, by combining matrix isolation infrared spectroscopy with ab initio and DFT computational methodologies. The respective potential energy surfaces of the PCl3-C2H2 and PCl3-C2H4 heterodimers reveal unique minima stabilized by a concert of reasonably strong to weak interactions, of which Pπ phosphorus bonding was energetically dominant. Heterodimers, trimers and tetramers bound primarily by this unique phosphorus bond were generated at low temperatures. The dominance of phosphorus bonding in the PCl3-C2H2 and PCl3-C2H4 heterodimers over other interactions (such as Hπ, HCl, HP, Clπ and lone pair-π interactions) was confirmed and substantiated using extended quantum theory of atoms in molecules, natural bond orbital, electrostatic potential mapping and energy decomposition analyses. The following inferences in correlation with results from non-covalent-interaction analysis offer a complete understanding of the nature of the Pπ phosphorus bonding interactions. The significance of electrostatic forces kinetically favoring the formation of phosphorus bonded heterodimers, in addition to thermodynamic stabilization, is demonstrated experimentally.

Impact of communication on family satisfaction and anxiety in critical care

Objective

The objectives of this study were to explore the impact of a communication course for doctors on family satisfaction and anxiety in an Australasian ICU and to elucidate the determinants of family satisfaction and anxiety.

Design

Prospective observational study. Pre- and post-study design.

Participants

One hundred and three consecutive family members of patients staying in the ICU for more than 48 hours were identified. Eighty-six subjects were evaluated and analysed.

Methods

Ten-point Likert scale (FS-ICU Questionnaire) used to measure satisfaction. Hospital Anxiety and Depression Scale was used to measure anxiety. Study performed over a 12-week period (9 weeks pre- and 3 weeks post-course) in a 34-bed intensive care unit before and after a communication course for junior medical officers.

Results

Fifty-six subjects were approached for the purpose of this study. Forty-three family members were included, 40 of patients who survived, and 3 whose relative died in ICU. Overall family satisfaction was high (mean scores 9.44 ± 0.91). Post-course, 47 subjects were approached for the purpose of this study and 43 family members consented to participate. Overall family satisfaction was high (mean scores 9.84 ± 0.97). There was a statistically significant difference in the frequency of doctors’ communication before and after the course (P < 0.01) and anxiety levels (P = 0.0001)

Conclusion

The majority of families are happy with their care in the ICU. A communication course aimed at junior medical officers was effective in improving satisfaction and reducing anxiety among family members.

Disclosure of interest

The author has not supplied his/her declaration of competing interest.

Strong proton-shared hydrogen bonding in a methyl imidazole⋯HCl complex: evidence from matrix isolation infrared spectroscopy and ab initio computations

Evidence for proton-shared hydrogen bonding is provided in a methyl imidazole⋯HCl complex using matrix isolation infrared spectroscopy and ab initio computations.

Prototypical cyclohexane dimers: spectroscopic evidence for σ stacking at low temperatures

In this work, the first unambiguous spectroscopic evidence for the existence of σ stacking interactions in cyclohexane dimers has been provided using matrix isolation infrared spectroscopy.

Patterns of Depressive Symptoms Before and After Surgery for Osteoarthritis: A Descriptive Study

Objective

To examine patterns of depressive symptoms before and over the year following osteoarthritis (OA) surgery, stratified by joint and postsurgical outcome.

Methods

Participants were hip (n = 287), knee (n = 360), and lumbar spine (n = 100) OA patients scheduled for joint replacement or decompression surgery with or without fusion. One pre‐ and 4 postsurgery questionnaires were completed. Depressive symptoms were quantified using the Hospital Anxiety and Depression Scale (HADS). One‐year outcomes were based on Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scores for hip and knee patients and Oswestry Disability Index (ODI) scores for spine patients and were categorized as “worse” (top score tertile) vs. “better” outcomes (first, second tertiles). Plots over time were generated by joint and outcome: 1) mean pain/disability and depression scores and 2) percentage of patients meeting HADS cut‐off for depression “caseness,” reporting depression diagnosis and treatment.

Results

There were notable decreases in depression scores for patients with better outcomes. For those with worse outcomes, decreases were smaller for hip patients and were not significant for knee and spine patients. Among those with poorer outcomes, 25% of spine and knee patients were depression “cases” pre‐ and postsurgery; an additional 16% of spine and 10% of knee patients developed new “caseness” postsurgery. The proportion of these patients deemed depression cases by score was much higher than the proportion reporting diagnosis/treatment.

Conclusion

Although depressive symptoms decrease overall in OA patients postsurgery, degrees of change vary by joint and surgical outcome. Greater attention to mental health postsurgery is warranted and may lead to improved surgical outcomes, particularly among knee and spine patients.

Conformations of diethyl ether and its interaction with pyrrole at low temperatures

Conformations of diethyl ether (DEE) were studied at low temperatures in N₂ and Ar matrixes. Computations performed at B3LYP/aug-cc-pVDZ level of theory yielded three minima corresponding to tt, tg^± and g^±g^± conformers of DEE. Of the three, the tt and tg^± conformers of DEE were experimentally identified in N₂ and Ar matrixes. Furthermore, hydrogen bonded complexes of pyrrole (py) with DEE have been investigated using Density Functional Theory (DFT) and matrix isolation infrared spectroscopy. Computations performed at B3LYP level of theory using aug-cc-pVDZ basis set on pyrrole with tt and tg^± conformers of DEE gave py-DEE-tt and py-DEE-tg^± complexes, both characterized by NH⋯O interaction. Experimental evidence for the formation of py-DEE-tt and py-DEE-tg^± complexes was affirmed from the shifts in the NH stretching, NH bending regions of pyrrole and COC and CH stretching regions of DEE. NBO analysis was carried out to understand the charge-transfer delocalization interactions in the conformers of DEE and its hydrogen bonded complexes.

Elusive hypervalent phosphorus⋯π interactions: evidence for paradigm transformation from hydrogen to phosphorus bonding at low temperatures

A paradigm transformation from hydrogen to phosphorus bonding is found to depend on the proton affinity of the interacting π-systems.

Development of an experimental set-up for low-temperature spectroscopic studies of matrix-isolated molecules and molecular ices using synchrotron radiation

An experimental set-up for studying photophysics and photochemistry of molecules in an inert gas medium (matrix-isolated) and in the ice phase at low temperatures has been developed and commissioned at the Photophysics beamline, Indus-1 synchrotron radiation source. This end-station uses an in-house-developed closed-cycle cryostat for achieving cryo-temperatures (∼10 K). Synchrotron radiation from the Photophysics beamline is used as the source of UV-VUV photons and the system is equipped with a Fourier transform infrared spectrometer for characterization of the molecular species formed at low temperature. Various individual components of the end-station like closed-cycle cryostat, experimental chamber, gas mixing and deposition systems are tested to ascertain that the desired performance criteria are satisfied. The performance of the composite system after integration with the Photophysics beamline is evaluated by recording IR and UV-VUV photoabsorption spectra of sulfur dioxide at low temperatures (10 K), both in the ice phase as well as isolated in argon matrices. Results obtained are in good agreement with earlier literature, thus validating the satisfactory performance of the system. As an off-shoot of the study, the VUV absorption spectrum of matrix-isolated SO₂ in argon matrix up to 10.2 eV is reported here for the first time. This experimental end-station will provide new opportunities to study photon-induced reactions in molecules of environmental, astrochemical and industrial importance. Details of the design, development and initial experimental results obtained are presented.

A classification modeling approach for determining metabolite signatures in osteoarthritis

Multiple factors can help predict knee osteoarthritis (OA) patients from healthy individuals, including age, sex, and BMI, and possibly metabolite levels. Using plasma from individuals with primary OA undergoing total knee replacement and healthy volunteers, we measured lysophosphatidylcholine (lysoPC) and phosphatidylcholine (PC) analogues by metabolomics. Populations were stratified on demographic factors and lysoPC and PC analogue signatures were determined by univariate receiver-operator curve (AUC) analysis. Using signatures, multivariate classification modeling was performed using various algorithms to select the most consistent method as measured by AUC differences between resampled training and test sets. Lists of metabolites indicative of OA [AUC > 0.5] were identified for each stratum. The signature from males age > 50 years old encompassed the majority of identified metabolites, suggesting lysoPCs and PCs are dominant indicators of OA in older males. Principal component regression with logistic regression was the most consistent multivariate classification algorithm tested. Using this algorithm, classification of older males had fair power to classify OA patients from healthy individuals. Thus, individual levels of lysoPC and PC analogues may be indicative of individuals with OA in older populations, particularly males. Our metabolite signature modeling method is likely to increase classification power in validation cohorts.

Uranyl tris nitrato as a luminescent probe for trace water detection in acetonitrile

Uranyl tris nitrato i.e. [UO₂ (NO₃ )₃ ]^- was formed by adding tetramethylammonium nitrate to uranyl nitrate in acetonitrile medium. The luminescence features of this complex in acetonitrile are very sensitive to water content, which could lead to the use of it as a luminescent probe for water present in acetonitrile. The luminescence intensity ratio of 507 to 467 nm peak of uranyl tris nitrato showed a linear response in the range 0-5% (v/v) water content in acetonitrile. The present method was applied for three synthetic samples of acetonitrile for water detection and the results obtained were compared using Karl Fischer titration. There was a good agreement in the values obtained by both the methods.

Pentavalent phosphorus as a unique phosphorus donor in POCl3 homodimer and POCl3–H2O heterodimer: matrix isolation infrared spectroscopic and computational studies

Phosphorus, an important element among the pnicogen group, opens up avenues for experimental and computational explorations of its interaction in a variety of compounds.

Elderly patients are at high risk of night-time admission to the intensive care unit following a rapid response team call

Previous studies have shown that elderly patients (age ≥65 years) are less likely to be admitted to the intensive care unit following a rapid response team call and have high hospital mortality rates. This study has shown that elderly patients have a significantly higher probability of being admitted to an intensive care unit following a rapid response team call at night than during the day. However, at no time are they at greater risk than younger patients of incomplete vital sign recording, a failure to escalate care for acute deterioration or mortality.

Experimental evidence for the blue-shifted hydrogen-bonded complexes of CHF3 with π-electron donors

Blue-shifted hydrogen-bonded complexes of fluoroform (CHF₃) with benzene (C₆H₆) and acetylene (C₂H₂) have been investigated using matrix isolation infrared spectroscopy and ab initio computations. For CHF₃-C₆H₆ complex, calculations performed at the B3LYP and MP2 levels of theory using 6-311++G (d,p) and aug-cc-pVDZ basis sets discerned two minima corresponding to a 1:1 hydrogen-bonded complex. The global minimum correlated to a structure, where the interaction is between the hydrogen of CHF₃ and the π-electrons of C₆H₆ and a weak local minimum was stabilized through H…F interaction. For the CHF₃-C₂H₂ complex, computation performed at MP2/aug-cc-pVDZ level of theory yielded two minima, corresponding to the cyclic C-H…π complex A (global) and a linear C-H…F (n-σ) complex B (local). Experimentally a blue-shift of 32.3cm^-1 and 7.7cm^-1 was observed in the ν₁ C-H stretching mode of CHF₃ sub-molecule in Ar matrix for the 1:1 C-H…π complexes of CHF₃ with C₆H₆ and C₂H₂ respectively. Natural bond orbital (NBO), Atoms-in-molecule (AIM) and energy decomposition (EDA) analyses were carried out to explain the blue-shifting and the nature of the interaction in these complexes.