Tailoring Waterborne Coating Rheology with Hydrophobically Modified Ethoxylated Urethanes (HEURs): Molecular Architecture Insights Supported by CG-MD Simulations.

A novel investigation of the effects of the hydrophilic and hydrophobic segments of hydrophobically modified ethoxylated urethanes (HEURs) on the rheological properties of their aqueous solutions, latex-based emulsions, and waterborne paints is demonstrated. Different HEUR thickeners were produced by varying the poly(ethylene glycol) (PEG) molecular weight and terminal hydrophobic size. Results reveal that the strength of hydrophobic associations and, consequently, the rheological properties of HEUR formulations can be effectively controlled by modifying the structure of the hydrophobic segment, specifically, the combination of diisocyanate and monoalcohol. This allows for the on-demand attainment of diverse rheological behaviors ranging from predominantly Newtonian profiles exhibiting lower viscosities to markedly pseudoplastic behaviors with significantly higher viscosities. The length of the hydrophilic group appears to affect viscosity only marginally up to a molecular weight of 23,000 g/mol, with more notable effects at 33,000 g/mol. Additionally, it was indicated that the rheological responses observed in water solutions provide a reliable forecast of their behavior in latex-based emulsions and waterborne paints. Coarse-grained molecular dynamics (CG-MD) simulations were also applied to gain insight into HEUR micelle dynamics in aqueous solutions. Guided by the DBSCAN algorithm, the simulations successfully captured the concentration-dependent behavior and the impact of hydrophilic chain length, aligning with the experimental viscosity trends. Various metrics were employed to provide a comprehensive analysis of the micellization process, including the hydrophobic cluster volume, the total micellar volume, the aggregation number, and the number of chains interconnecting with other micelles.

Insight Into Solventless Production of Hydrophobically Modified Ethoxylated Urethanes (HEURs): The Role of Moisture Concentration, Reaction Temperature, and Mixing Efficiency.

In this work, we report for the first time on the influence of the quality of reactants and reaction conditions on the production of hydrophobically modified ethoxylated urethanes (HEURs) and selected prepolymers without the use of solvents. We show that the polyol water concentration is detrimental to the progress of the main urethane forming reaction, confirming the necessity of carefully drying the reactants below 1000 ppm to suppress the consumption of diisocyanate toward urea during HEUR synthesis. Increasing the mixing speed (≈30 to 750 rpm), reaction temperature (80-110 °C), and catalyst concentration (0.035-2.1 wt % bismuth carboxylate) can significantly increase the rate of molecular weight buildup, but their effect decreases with time as the bulk viscosity increases and mixing limitations eventually take over, leading to the Weissenberg effect and chain growth termination. Consequently, for the selected formulation, the maximum product molecular weight attained lies in the range of ≈20 000-22 000 g/mol, irrespective of the specific process conditions applied.

In situ generation of radical initiators using amine-borane complexes for carbohalogenation of alkenes.

Atom transfer radical addition of alkyl halides to alkenes was developed using a low amount of a stable initiator, amine borane complexes. Thanks to a slow hydroboration step, the overall carbohalogenation process leads to good isolated yields.

High-Throughput Screening of the Alkoxide/Oxime-Based Library: An Alternative to Organotin Compounds for the Alkoxysilane Condensation in Adhesives and Sealants.

In this work, a high-throughput screening (HTS) method was used to discover new efficient catalysts to substitute organotin compounds (DBTDL) for the cross-linking of silyl-modified polymers (SMPs). We report here on the use of our HTS method to investigate a library of alkoxide/oxime systems with different metal/ligand (M/L) ratios. Among the 156 candidates tested, 40 interesting hits were detected. Then, the cross-linking times for the better hits were measured on the SMP. Some of these seem to be more efficient than DBTDL and exhibit a good stability during storage in cartridges. Thereby, a high efficiency of alkoxide/oxime systems was established that shows great potential for the generation of new ligands to provide new tin-free catalysts for the cross-linking of adhesives and sealants.

α,ω-Epoxide, Oxetane, and Dithiocarbonate Telechelic Copolyolefins: Access by Ring-Opening Metathesis/Cross-Metathesis Polymerization (ROMP/CM) of Cycloolefins in the Presence of Functional Symmetric Chain-Transfer Agents.

Epoxide- and oxetane-α,ω-telechelic (co)polyolefins have been successfully synthesized by the tandem ring-opening metathesis polymerization (ROMP)/cross-metathesis (CM) of cyclic olefins using Grubbs' second-generation catalyst (G2) in the presence of a bifunctional symmetric alkene epoxide- or oxetane-functionalized chain-transfer agent (CTA). From cyclooctene (COE), trans,trans,cis-1,5,9-cyclododecatriene (CDT), norbornene (NB), and methyl 5-norbornene-2-carboxylate (NBCOOMe), with bis(oxiran-2-ylmethyl) maleate (CTA 1), bis(oxetane-2-ylmethyl) maleate (CTA 2), or bis(oxetane-2-ylmethyl) (E)-hex-3-enedioate (CTA 3), well-defined α,ω-di(epoxide or oxetane) telechelic PCOEs, P(COE-co-NB or -NBCOOMe)s, and P(NB-co-CDT)s were isolated under mild operating conditions (40 or 60 °C, 24 h). The oxetane CTA 3 and the epoxide CTA 1 were revealed to be significantly more efficient in the CM step than CTA 2, which apparently inhibits the reaction. Quantitative dithiocarbonatation (CS2/LiBr, 40 °C, THF) of an α,ω-di(epoxide) telechelic P(NB-co-CDT) afforded a convenient approach to the analogous α,ω-bis(dithiocarbonate) telechelic P(NB-co-CDT). The nature of the end-capping function of the epoxide/oxetane/dithiocarbonate telechelic P(NB-co-CDT)s did not impact their thermal signature, as measured by DSC. These copolymers also displayed a low viscosity liquid-like behavior and a shear thinning rheological behavior.

Comparison of phonomyography, kinemyography and mechanomyography for neuromuscular monitoring.

PURPOSE: The gold standard of neuromuscular monitoring is mechanomyography (MMG). Phonomyography (PMG) and kinemyography (KMG) are new methods of neuromuscular monitoring. In this study, all three methods were compared to determine neuromuscular blockade at the adductor pollicis muscle. METHODS: In 14 patients, phonomyography was recorded via a microphone taped to the thenar region. A standard mechanomyographic device was applied to the same thumb, and attached to the force transducer. On the contralateral side, a NMT-Mechanosensor(R) probe was attached to the thumb and forefinger (KMG). After induction of general anaesthesia, the ulnar nerves were stimulated supramaximally using superficial electrodes at the wrists using train-of-four (TOF) stimulation every 12 sec. Onset and recovery indices measured by the three methods after mivacurium 0.2 mg x kg(-1) iv were compared using ANOVA-multiple group comparisons. Agreement between methods was determined using Lin's concordance correlation coefficient. RESULTS: Onset time and peak effect measured via MMG and PMG were similar. Recovery times from neuromuscular blockade (NMB) as measured via the three methods were not different. Agreement between PMG and MMG was excellent for onset and offset of NMB but unsatisfactory for peak effect. Agreement between MMG and KMG was satisfactory for TOF 0.25 and 0.50, and excellent for TOF 0.75 and 0.90 (onset and peak effect not determined for KMG). Agreement between PMG and KMG was satisfactory for TOF 0.25, 0.50 and 0.75, and excellent for TOF 0.90. CONCLUSION: Mechanomyography, PMG and KMG show satisfactory agreement for determination of recovery of NMB for clinical purposes.

Monitoring neuromuscular blockade at the vastus medialis muscle using phonomyography.

PURPOSE: The vastus medialis muscle has been recently proposed as a new site for monitoring neuromuscular blockade (NMB). The purpose of this study is to compare NMB at the vastus medialis with the adductor pollicis muscle using phonomyography (PMG). METHODS: Fifteen patients were enrolled in the study. Anesthesia was induced with remifentanil 0.25 to 0.5 microg x kg(-1) x min(-1), followed by propofol 2 to 2.5 mg(-1) x kg(-1) iv. Analgesia was provided by remifentanil 0.05 to 0.25 microg x kg (-1) x min(-1) iv throughout surgery. A small piezo-electric microphone was attached to the middle of the thenar mass of the right hand to record acoustic signals produced by the contraction of the adductor pollicis muscle. A second microphone was fixed to the medial part of the thigh, 10 cm over the patella, to record the response from the vastus medialis muscle. The ulnar nerve and the im branches of the femoral nerve were stimulated using train-of-four stimulation every 12 sec. Onset, maximum effect, and offset of neuromuscular block were measured after mivacurium 0.2 mg x kg(-1) iv and compared. RESULTS: At the vastus medialis muscle, the onset of NMB was significantly shorter at 1.9 +/- 0.6 min vs 2.8 +/- 0.7 min, the maximum effect less pronounced at 85 +/- 11% vs 96 +/- 2% and recovery of NMB to 25%, 75%, 90% of twitch control height more rapid than at the adductor pollicis muscle at 17 +/- 2.2 min vs 21.6 +/- 4.2 min, 26.7 +/- 6.5 vs 21 +/- 4.1 min and 30.7 +/- 6.6 vs 35.9 +/- 7.1 min, respectively. CONCLUSIONS: PMG can be used to measure NMB at the vastus medialis muscle. We found a shorter onset time, less pronounced maximum effect and more rapid recovery of NMB at the vastus medialis muscle than at the adductor pollicis muscle.

Haptic shape discrimination in humans: insight into haptic frames of reference.

This study investigates how a change in the physical relation between objects (two-dimensional, 2-D, angles) and a subject, as well as scanning conditions, modify the ability to discriminate small changes in 2-D shape. Subjects scanned pairs of angles (90 masculine standard; 91 masculine-103 masculine comparison angles) with the right index finger of the out-stretched arm, identifying the larger of each pair. When joint rotation was restricted to the shoulder, the discrimination threshold significantly increased when the angles were explored with the shoulder in a more eccentric position rather than closer to the midline (60 masculine versus 30 masculine to the right). This result was attributed to changes in proprioceptive sensitivity, since explorations restricted to distal joints (wrist/second metacarpophalangeal joint) showed no change with shoulder position. The results showed, moreover, that discrimination threshold was similar for distal and proximal joints when the delay between scanning the pairs of angles was long (15 s). This observation suggests that regional variations in proprioceptive acuity (proximal>distal) may reflect an adaptation to generate an invariant central representation of haptic shape. Using a shorter interscan delay (5 s), a position-dependent increase in discrimination threshold was revealed for distal explorations, an effect that disappeared when the head was turned in the direction of the unseen angle (vision occluded). We suggest that these results can be explained by the existence of two competing egocentric frames of reference with different time courses, one of short duration that is centred on the arm/hand, and a second of longer duration centred on the head. At the short delay, the reference frames interacted to distort the haptic representation when they were misaligned. This distortion was resolved at the long delay, possibly through suppression of the arm/hand-centred reference frame.

An external monitoring site at the neck cannot be used to measure neuromuscular blockade of the larynx.

Using phonomyography, a new monitoring technique of neuromuscular blockade (NMB), we compared NMB after mivacurium 0.1 mg/kg at the lateral cricoarytenoid muscle (LCA) with a possible external monitoring site of the larynx. In 12 patients, data were obtained at both sites using phonomyography. Anesthesia was induced with remifentanil 0.25-0.5 microg . kg(-1) . min(-1) followed by propofol 2-3 mg/kg. A small piezo-electric microphone was positioned beside the vocal cords into the muscular process at the base of the arytenoid cartilage to record acoustic signals from the contraction of the LCA. A second microphone was positioned at an external site, lateral to the trachea, just below the thyroid notch. The recurrent laryngeal nerve was stimulated supramaximally using train-of-four (TOF) stimulation every 12 s. Onset, maximum effect, and offset of NMB were measured and compared. Peak effect, time to reach (T) 25%, 75%, and 90% of control twitch response, and TOF recovery to TOF ratios 0.5-0.8 were significantly longer at the external site. The onset time was not significantly different between the two sites. We used phonomyography with a microphone placed at the neck to evaluate the possibility to externally monitor NMB at the larynx. When compared with LCA, we found a more pronounced peak effect and longer offset of NMB. The acoustic signals recorded at this external site are unlikely to stem from laryngeal muscle contraction but are rather a result of contraction of the strap muscles of the neck.

Dominance of the hand does not change the phonomyographic measurement of neuromuscular block at the adductor pollicis muscle.

Phonomyography (PMG) is a novel method to determine neuromuscular blockade (NMB) with high sensitivity and applicability at all muscles. The adductor pollicis muscle has long been used in research and clinical practice as reference for neuromuscular monitoring. The goal of our study was to compare PMG signals (train-of-four [TOF] ratios and T(1)/T(0) values) from both hands of the same patient to investigate the influence of hand dominance on neuromuscular monitoring. In 14 patients, PMG was recorded via small piezoelectric microphones taped over the thenar mass of both hands. After induction of anesthesia, both ulnar nerves were stimulated supramaximally using TOF stimulation every 12 s. Mivacurium 0.2 mg/kg was administered within 5 s. Onset, maximum effect, and offset of NMB were compared between both adductor pollicis muscles. Twelve patients were right-handed and two patients were left-handed. No statistical difference was found between the signals from the dominant or nondominant hand. Correlation was very good (r = 0.95). Agreement was excellent with a bias of -0.57% and limits of agreement of -17.9% to 16.7% (dominant - nondominant hand). This study shows minimal bias, good correlation and no statistical difference when NMB is monitored at both the dominant and nondominant adductor pollicis muscles. Both hands could be used interchangeably to assess NMB at the adductor pollicis muscle.

Phonomyographic measurements of neuromuscular blockade are similar to mechanomyography for hand muscles.

PURPOSE: Phonomyography consists of recording low frequency sounds created during muscle contraction. In this study, phonomyography of three regions of the hand was compared to mechanomyography of the adductor pollicis. METHODS: In 12 patients, phonomyography was recorded via small condenser microphones taped over the thenar mass, the hypothenar eminence, and the dorsal groove between the first and second metacarpal bones to record the acoustic signals of adductor pollicis and the hypothenar and first dorsal interosseus muscles, respectively. Mechanomyography of the adductor pollicis was recorded simultaneously using a force transducer. After induction of anesthesia, the ulnar nerve was stimulated supramaximally using train-of-four (TOF) stimulation every 12 sec. Onset, maximum effect, and offset of neuromuscular block after rocuronium 0.6 mg x kg(-1) were measured using phonomyography and compared to mechanomyography using ANOVA and the Bland-Altman test. RESULTS: Phonomyographic measurements of onset and maximum effect of neuromuscular blockade were not significantly different from mechanomyographic measurements. Phonomyographic measurements of offset (T25%, T75 %, TOF 0.8) of neuromuscular block at the thenar muscles and first dorsal interosseus muscles were not significantly different from mechanomyographic measurements at adductor pollicis; however, T50%, T75% and T90% phonomyographic measurements at the hypothenar muscle were significantly shorter than at any other muscle site. CONCLUSION: There was good agreement between mechanomyographic measurements at the adductor pollicis muscle and phonomyographic measurements at the thenar and the first dorsal interosseus muscles. Phonomyography of those two muscles could be used interchangeably with mechanomyography of adductor pollicis for clinical purposes.

Simultaneous determination of neuromuscular blockade at the adducting and abducting laryngeal muscles using phonomyography.

UNLABELLED: Phonomyography (PMG) is a new method for measuring neuromuscular blockade (NMB) at the larynx. In this study, we used PMG to compare NMB at the posterior cricoarytenoid (PCA) and the lateral cricoarytenoid muscle (LCA) in humans. Twelve patients were included in this study. Endotracheal intubation was performed without aid of neuromuscular blocking drugs. One small condenser microphone was inserted beside the vocal cords into the muscular process at the base of the arytenoid cartilage to record acoustic responses of the LCA (vocal cord adduction), and a second microphone was placed behind the larynx to measure NMB of the PCA (vocal cord abduction). Stimulation of the recurrent laryngeal nerve was performed using superficial electrodes placed at the neck (midline between jugular notch and cricoid cartilage) using train-of-four (TOF) stimulation every 12 s. After supramaximal stimulation, mivacurium 0.1 mg/kg was injected and onset, peak effect, and offset of NMB measured and compared using t-test (P < 0.05). The data are presented as mean (SD). Peak effect, onset time, and early recovery to 25% of control twitch height were not significantly different between PCA and LCA at 86% (13) versus 78% (16), 2.3 min (0.45) versus 2.3 min (1.0), and 9.55 min (3.05) versus 8.5 min (4.7), respectively. However, recovery to 75%, 90% of control twitch height, and recovery to a TOF ratio of 0.8 were significantly longer at the PCA than at the LCA at 14 min (4) versus 11 min (5), 17 min (5) versus 11.8 min (5.6), and 17.5 min (5.6) versus 12.3 min (5.5), respectively. The authors conclude that recovery of NMB at the PCA takes longer than at the LCA in humans after mivacurium. IMPLICATIONS: After neuromuscular blockade in humans, the recovery of the ability to open the vocal cords takes longer than the ability to close the vocal cords.

Comparison of phonomyography with balloon pressure mechanomyography to measure contractile force at the corrugator supercilii muscle.

PURPOSE: Phonomyography is based on the creation of low frequency sounds during muscle contraction, which can be recorded and used for neuromuscular monitoring. In this study, balloon pressure mechanomyography, a novel method to measure the force of contraction via pressure changes in an air-filled balloon, was compared with phonomyography to determine neuromuscular blockade at the corrugator supercilii muscle. METHOD: After approval of the Ethics Committee and informed consent, 15 patients were studied. A small condenser microphone was taped to the area just above the eyebrow for phonomyography; an air-filled balloon was taped to the area just above the opposite eyebrow. After induction of anesthesia using remifentanil and propofol, a laryngeal mask airway was inserted without the aid of neuromuscular blocking agents. The facial nerve was stimulated supramaximally with single-twitch stimulation (0.1 Hz) using superficial electrodes placed on both temporal areas for onset and train-of-four stimulation every 12 sec during offset of neuromuscular blockade produced by mivacurium 0.1 mg.kg(-1). Onset and recovery measured by the two methods were compared using the t test and agreement between phonomyography and balloon pressure mechanomyography was examined using the Bland-Altman method. RESULTS: Onset, peak effect, and time to reach 25%, 75%, and 90% of control twitch response for phonomyography vs balloon pressure method were 83 +/- 16 sec vs 81 +/- 15 sec, 80 +/- 15% vs 82 +/- 17%, 7.7 +/- 2.3 min vs 7.5 +/- 2.4 min, 9.9 +/- 4.1 min vs 10.5 +/- 4 min, and 12.6 +/- 4.3 min vs 13.1 +/- 4.5 min respectively without being significantly different. Mean bias was 1% with limits of agreement of -9 and +9% of twitch height (T1). CONCLUSION: We applied a balloon pressure method to measure the force at the corrugator supercilii. Phonomyography at the corrugator supercilii shows good agreement with this modified version of mechanomyography.

Phonomyography and mechanomyography can be used interchangeably to measure neuromuscular block at the adductor pollicis muscle.

UNLABELLED: The standard of neuromuscular monitoring is the measurement of the force of contraction (mechanomyography, MMG). Phonomyography (PMG) consists of recording low-frequency sounds created during muscle contraction. In this study, we compared and used both methods to determine neuromuscular blockade (NMB) at the adductor pollicis muscle. In 14 patients, PMG was recorded via a small condenser microphone taped to the thenar mass, and a standard mechanomyographic device was applied to the same arm. In another group of 14 patients, only PMG was measured. After induction of anesthesia, the ulnar nerve was stimulated supramaximally using single twitch stimulation (0.1 Hz) for onset and train-of-four (TOF) stimulation every 12 s during offset of NMB produced by mivacurium 0.1 mg/kg. Onset and recovery indices measured by the 2 methods were compared using Student's t-test (P < 0.05). Similar comparisons were made between the two PMG groups (with or without special board). Agreement between PMG and MMG was examined using a Bland-Altman test. Onset was 165 (68) s versus 172 (67) s [mean (SD)], and maximum blockade was 89 (10)% versus 90 (11)%, for PMG and MMG respectively (NS). Time to 25%, 75%, and 90% recovery was 16.5 (4.2) min, 22.1 (6.9) min, and 24.5 (8.2) min, respectively for PMG, not different from 16.7 (4) min, 22.8 (8.1) min, and 24.8 (8.8) min for MMG. Mean bias was 0% with limits of agreement of -10 and + 10% of twitch height for all signals (MMG minus PMG). Time to TOF of 0.5, 0.7, 0.8, and 0.9, was 1 min faster with PMG than with MMG, with limits of agreement of -1.5 to 3.5 min. Pharmacodynamic data derived without or with special arm fixation were not significantly different. MMG and PMG can be used interchangeably to determine NMB at the adductor pollicis muscle. PMG is easier to apply, does not need a special monitoring board and could be a reliable monitor to determine NMB in daily routine. IMPLICATIONS: Mechanomyography and phonomyography (PMG), a novel method of monitoring neuromuscular blockade (NMB) by recording low-frequency sounds emitted by muscle contraction, can be used interchangeably to determine NMB at the adductor pollicis muscle. PMG is easier to apply, does not need a special monitoring board and could be a reliable monitor to determine NMB in daily routine.

A strategy for the stereoselective synthesis of unsymmetric atropisomeric ligands: preparation of NAPhePHOS, a new biaryl diphosphine.

MeO-NAPhePHOS represents the first example of a new series of atropisomeric diphosphines bearing heterotopic biaryl moieties. The key step of its synthesis is the diastereoselective, intramolecular, Cu(I)-promoted coupling of 1-iodonaphthol and 2-iodo-3-methoxyphenol connected by a chiral tether. (R,R)-2,4-Pentanediol is used as the chiral auxiliary in this highly selective reaction that leads to a single enantiomer of the title diphosphine. In the Ru-promoted hydrogenations of carbonyl derivatives, NAPhePHOS affords enantioselectivity levels fully comparable to those of the C(2)-symmetrical analogues, BINAP and MeO-BIPHEP respectively, thus showing that the lack of C(2) symmetry is not detrimental to the catalytic properties of atropisomeric ligands in these hydrogenation reactions.