77 % Photothermal Conversion in Blatter-Type Diradicals: Photophysics and Photodynamic Applications.

Diradicals based on the Blatter units and connected by acetylene and alkene spacers have been prepared. All the molecules show sizably large diradical character and low energy singlet-triplet gaps. Their photo-physical properties concerning their lowest energy excited state have been studied in detail by steady-state and time-resolved absorption spectroscopy. We have fully identified the main optical absorption band and full absence of emission from the lowest energy excited state. A computational study has been also carried out that has helped to identify the presence of a conical intersection between the lowest energy excited state and the ground state which produces a highly efficient light-to-heat conversion of the absorbed radiation. Furthermore, an outstanding photo-thermal conversion 77.23 % has been confirmed, close to the highest in the diradicaloid field. For the first time, stable diradicals are applied to photo-thermal therapy of tumor cells with good stability and satisfactory performance at near-infrared region.

Management of chronic Stanford type A aortic dissection combined with Neri type C coronary occlusion: a case report and literature review.

While there are many reports on partial aortic root remodelling, it is rarely performed for chronic aortic dissection of the coronary artery. This case report describes a 71-year-old male patient with chronic aortic dissection who was admitted to hospital due to repeated palpitations and chest distress. He had a long-term occlusion of the right coronary artery and an abnormal origin of the left vertebral artery. A carefully planned surgical strategy was arranged for this patient, and the surgical experience is described and discussed herein. Briefly, the patient was treated by aortic root repair plus ascending aorta replacement plus Sun's procedure plus left vertebral artery graft implantation plus coronary artery bypass graft (right coronary artery to saphenous vein to innominate artery). At approximately 6 months following surgery, the patient had returned to normal living conditions without any reports of discomfort.

Quasi-Free Electron States Responsible for Single-Molecule Conductance Enhancement in Stable Radical.

Stable organic radicals, which possess half-filled orbitals in the vicinity of the Fermi energy, are promising candidates for electronic devices. In this Letter, using a combination of scanning-tunneling-microscopy-based break junction (STM-BJ) experiments and quantum transport theory, a stable fluorene-based radical is investigated. We demonstrate that the transport properties of a series of fluorene derivatives can be tuned by controlling the degree of localization of certain orbitals. More specifically, radical 36-FR has a delocalized half-filled orbital resulting in Breit-Wigner resonances, leading to an unprecedented conductance enhancement of 2 orders of magnitude larger than the neutral nonradical counterpart (36-FOH). In other words, conversion from a closed-shell fluorene derivative to the free radical in 36-FR opens an electron transport path which massively enhances the conductance. This new understanding of the role of radicals in single-molecule junctions opens up a novel design strategy for single-molecule-based spintronic devices.

Systematic Retrospective Analysis of Risk Factors and Preventive Measures of Bone Cement Leakage in Percutaneous Kyphoplasty.

OBJECTIVE: In this study, we aimed to analyze the risk factors of bone cement leakage in percutaneous kyphoplasty (PKP) treatment of osteoporotic vertebral compression fractures (OVCFs), and provide suggestions for reducing bone cement leakage. METHODS: A retrospective study of 517 cases of OVCFs treated with PKP were divided into 2 groups according to whether they had bone cement leakage or not, leakage group (n = 72) and non-leakage group (n = 445). The risk factors of leakage were systematically analyzed using clinical baseline data, imaging observation data, and surgery-related factors. To select the statistically significant results (P < 0.05) among the risk factors mentioned above, we used the binary logistic regression method to identify the main risk factors. RESULTS: The univariate analysis of clinical baseline data，imaging observation data, and surgery-related factors showed that bone mineral density (BMD) (P < 0.001), hypertension (P < 0.05), injury factors (P < 0.01), cortical defect (P < 0.001), grade of vertebral compression (P < 0.001), surgical approach (P < 0.05), stage of bone cement injection (P < 0.01), and balloon pressure (P < 0.05) were the risk factors for bone cement leakage. The recovery rate of vertebral height, and the Cobb angle correction rate were lower in the bone cement leakage group (P < 0.001). The correction effect of kyphosis after operation was limited. Binary logistic analysis results showed that BMD (odds ratio [OR] 5.605), cortical defect (OR 3.115), and stage of bone cement injection (OR 2.385) were bone cement leakage-independent risk factors. CONCLUSIONS: Impairment of BMD value, defects of cortical bone, and inappropriate stage of bone cement injection will increase the risk of bone cement leakage in PKP treatment and limit PKP effects.

Comparison of clinical efficacy between retention and removal of the vertebral bony endplate in anterior cervical discectomy and fusion for the treatment of cervical spondylotic myelopathy.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) have a history of more than 60 years to treat cervical spondylotic myelopathy. This study is based on the original classic surgical procedure to remove the bony endplate to expand the range of vertical decompression to analyze and compare the clinical efficacy of two different ACDF in treating cervical spondylotic myelopathy. METHODS: The inpatients in hospital were randomly divided into two groups A and B. Patients in Group A received ACDF surgery with bony endplates preserved, and patients in group B received ACDF surgery with bony endplates removed. All patients were followed-up for three years, and then compared the clinical efficacy from the following aspects, blood loss statistics during and after the operation, Japanese Orthopedic Association's scoring (JOA) standard for cervical spondylotic myelopathy, Cervical curvature index, cervical flexion and extension range, intervertebral bone graft fusion time and fusion rate. RESULTS: 1. The operative time and intraoperative (postoperative) blood loss in group A were significantly better than that in group B, with statistical significance (P < 0.05)0.2. There was no significant difference in postoperative neurological function recovery, cervical curvature index, cervical flexion and extension activity, and Intervertebral fusion time between two groups (P > 0.05), while group A was superior to group B in terms of bone graft fusion rate (P < 0.05). 3. Four patients (6.7%) in group B suffered from dyspnea due to neck hematoma caused by drainage tube blockage, but all of them were cured immediately and no death occurred. CONCLUSIONS: During the 3-year follow-up period after the operation, six patients in group B have subsidence and loosening of the internal fixator due to bone subsidence around the implant. Although immediate surgical treatment is not required, renovation surgery is inevitable in the long term.

The effect of coupled inhibitory-facilitatory repetitive transcranial magnetic stimulation on shaping early reorganization of the motor network after stroke.

Neural plasticity is a major factor driving cortical reorganization after stroke. This study aimed to evaluate functional connectivity (FC) changes in the cortical motor network after coupled inhibitory-facilitatory repetitive transcranial magnetic stimulation (rTMS) treatment and to assess the correlation between FC changes and functional recovery, further characterizing the neural mechanisms underlying the beneficial effects of rTMS. We randomly divided 63 patients with acute stroke into four groups: (1) Group A received coupled inhibitory-facilitatory rTMS [1 Hz over the contralesional primary motor cortex (M1) and 10 Hz over ipsilesional M1]; (2) Group B received a contralesional sham stimulation and ipsilesional 10 Hz stimulation; (3) Group C received a contralesional 1 Hz rTMS and ipsilesional sham stimulation; and (4) Group D received bilateral sham stimulation only. Standardized rehabilitation therapy was performed immediately after rTMS, and each group was treated with their respective treatment modalities for 4 weeks. Twenty-four hours before and after the intervention, participants underwent resting-state functional magnetic resonance imaging. Additional functional assessments were conducted at baseline, after treatment, and at the 3 month follow-up. The rTMS treatment significantly changed the FCs of intra- and inter-hemispheric cortical motor networks in the rTMS groups (A and B) compared with the sham group (Group D). This effect was more pronounced in Group A, which displayed a changed FC between the contralesional postcentral gyrus and contralesional superior parietal gyrus, between the contralesional precentral gyrus and contralesional postcentral gyrus, and between the ipsilesional postcentral gyrus and contralesional superior parietal gyrus, when compared with Groups B and C. Importantly, FC changes were significantly correlated with improvement of motor function. In the early stages of ischemic stroke, coupled rTMS was more conducive to motor recovery by modulating the FCs of intra-hemispheric and inter-hemispheric motor networks. Our results suggested that FC changes were related to motor function recovery for early-stage cerebral stroke patients treated with coupled rTMS. These findings could help to understand the mechanism of coupled rTMS and further the use of this therapy as an adjunct rehabilitation technique in motor recovery.

Enhanced photostability of aggregation induced emission by hydrophobic groups.

Since the aggregation induced emission (AIE) phenomenon was reported, many research groups have used this unique AIE effect to develop chemo- or bio-sensors for detecting ions, gases, explosives, proteins, and enzymes. Most of these sensors work in their aggregate state, therefore, fluorescence stability has become one of the important problem, and unfortunately, as far as we know, there is no paper to discuss what factors can improve the fluorescence stability of AIE compounds in the aggregate state, if the fluorescence stability of the sensors are poor, there will seriously affect the detection result. In this article, we found that compounds with hydrophobic long alkyl substituents can maintain stable fluorescence intensity for a long time in the aggregate state. In addition, cyclohexane is introduced as a hydrophobic substituent. Therefore, the fluorescence stability of the aggregates also increased by 90% within 1800s. The aggregation solutions of CB-3 and CSB-2 were left for two weeks, and no significant changes were found in the fluorescence intensity. Molecular dynamics simulation (MDS) shows that the presence of hydrophobic substituents in compounds cause the molecules to be closely interspersed with each other, hence, making it difficult to change the optical properties, microstructure and stacking mode of the AIE aggregates by external stimulations. The introduction of hydrophobic substituents improves the fluorescence stability of AIE compounds, and makes the AIE phenomenon more valuable in the fields of biological/chemical sensing and imaging.

New barbituric acid derivatives for data encryption and decryption based on the mechanochromic fluorescence effect.

Two barbituric acid derivatives CB-Ph and CB-Me were synthesized, both of which show a strong aggregation induced emission (AIE) effect. It was found that these two compounds show almost the same absorption and emission spectra. As a result, they show the same yellow color in daylight and the same yellow-green color under UV at 365 nm. Upon grinding, CB-Ph exhibits superior mechanochromic fluorescence (MCF) properties, with its fluorescence color from yellow-green (555 nm) to brown (580 nm) and its emission intensity decreases by 93%. However, neither the fluorescence peak wavelength nor the intensity of CB-Me shows observable changes after being ground, indicating no MCF effect. The X-ray diffraction (XRD) data indicate that the CB-Ph powder changes from the crystalline to amorphous state after being ground, whereas CB-Me remains in its crystalline state. Molecular dynamics simulation (MDS) shows that CB-Ph takes a 3D conformation due to three phenyl groups on the periphery of the molecule, which hinders the molecules from aggregating closely and results in the change of the microstructure by external force stimuli. However, CB-Me aggregated more closely due to its better planarity and hydrophobic n-hexane group, which make it difficult to change the microstructure upon being ground. Based on the unique optical properties of CB-Ph and CB-Me, a new data encryption-decryption technology is developed. CB-Ph is used as cryptographic ink due to its excellent MCF effect upon grinding. CB-Me is used as a camouflage material as it shows the same color as CB-Ph in the daylight and under UV-365 nm; furthermore, its colors remain unchanged after being ground.

LncRNA MALAT1 mediates proliferation of LPS treated-articular chondrocytes by targeting the miR-146a-PI3K/Akt/mTOR axis.

The study aimed to investigate the regulation of long noncoding RNA (lncRNA), Metastasis associated lung adenocarcinoma transcript 1 (MALAT1) in osteoarthritis (OA) development. Isolated rat chondrocytes treated with lipopolysaccharide (LPS) were used as OA cell model. Results from quantitative real-time PCR (Q-PCR) showed that, in OA patients and OA cell model, the expression of MALAT1 and PI3K was clearly reduced, while the miR-146a levels were increased. Next, MALAT1 was silenced in LPS-treated chondrocytes. Following with MALAT1 silencing, the generation of Cyclooxygenase-2 (COX-2), Interleukin-6 (IL-6) and Matrix metallopeptidase-13 (MMP-13) were promoted, while the level of type II collagen (COL2) was inhibited. Moreover, MALAT1 silencing caused a significant reduction in the proliferative rate of LPS-treated chondrocytes through inducing apoptosis. Bioinformatics prediction and dual-luciferase reporter assay (DLRA) results showed that MALAT1 targets miR-146a. MALAT1 silencing also resulted in the upregulation of miR-146a. Further studies revealed that miR-146a has the opposite effect on MALAT1, and its inhibition can antagonize the function of MALAT1 silencing on cell proliferation and apoptosis. Additionally, the 3'-UTR of the Phosphoinositide 3-kinase (PI3K) gene was found to be a target of miR-146a, while PI3K protein and mRNA expression, as well as the activation of downstream Akt and mammalian target of rapamycin (mTOR) were clearly reduced upon transfection with a miR-146a mimic. These results show that MALAT1 can modulate ECM catabolism, inflammation, and especially apoptosis in chondrocytes treated with LPS, which targets PI3K/Akt/mTOR to eventually regulate the progression of OA. Our findings provide a novel regulatory mechanism of MALAT1 in OA.

Multi-purpose barbituric acid derivatives with aggregation induced emission.

Three D-π-A barbituric acid derivatives with simple structure and intramolecular charge transfer (ICT) mechanisms were synthesized. Molecular dynamics simulations have successfully explained that CB-1 exhibits the best aggregate induced emission (AIE) activity due to the electron-deficient barbituric acid and the electron-rich carbazole exhibit a conformation which similar to π-π stacking, resulting in a strong electrostatic attraction between the molecules, meanwhile the N-atom substituent of the carbazole is n-propane plays a hydrophobic role. At the same time, barbituric acid derivatives also have mechanochromic fluorescent properties. In addition, CB-1 and CB-3 exhibited outstanding fluorescence stability than CB-2 in aggregation state which can be used to detect nitroaromatic explosives in aqueous media. The Stern-Volmer quenching constant (Ksv) of CB-1 and CB-3 is 6.6 × 104 and 1 × 105 M-1, respectively.

Detection of nitroaromatics based on aggregation induced emission of barbituric acid derivatives.

Barbituric acid derivatives with typical aggregation induced emission (AIE) are reported. Their emission wavelengths varied with water fraction of their solution. UV-visible absorption spectroscopy and theoretical calculations revealed the intramolecular charge transfer (ICT) possibility from donor to acceptor and the mechanism was confirmed as a restriction of intramolecular motion (RIM). The AIE properties were affected by the different substituents on barbituric acid. When the molecular volume increased, the AIE effect decreased. Fluorescent quenching mechanism was applied to detect nitroaromatic explosives. For 2,4,6-trinitrophenol (PA), one of the derivatives 5-(4-diphenylamino styrene)-1,3-diphenyl-barbituric acid in THF/H2O mixture (1:9, v/v), showed amplified fluorescence quenching with a maximum Stern-Volmer quenching constant of 4.1 × 104 M-1. The solid phase paper test based on 5-(4-diphenylamino styrene)-1,3-diphenyl-barbituric acid also showed a superior sensitivity toward PA both in vapor and solution.

Fabrication and characterization of a Cu-Pd-TNPs polymetallic nanoelectrode for electrochemically removing nitrate from groundwater.

A novel Cu-Pd-TNPs (Copper-Palladium-TiO2 Nanopores) polymetallic nanoelectrode was fabricated, and then used to catalytically reduce dissolved nitrate in groundwater. The aim was to develop a high efficient nanoelectrode for removing nitrate from groundwater. The Cu-Pd-TNPs polymetallic nanoelectrode was fabricated by plating Pd onto a TiO2 nanoporous matrix and then plating Cu onto the layer which is previous coating. TiO2 nanopores on the Cu-Pd-TNPs electrode surface gave the electrode a large specific surface area, and the Pd and Cu nanoparticles gave the electrode a high nitrogen to hydrogen ratio and a high nitrate reduction activity. Scanning electron microscopy images indicated that the Cu-Pd-TNPs polymetallic nanoelectrode was porous with lamellar deposits. The elements on the Cu-Pd-TNPs electrode surface, identified by energy-dispersive X-ray spectroscopy, were Ti, Pd, Cu, and O. The Cu-Pd-TNPs electrode gave a high nitrate reduction rate, removing 287.3% nitrate more than that was removed by a Ti nanoelectrode under the same conditions. The optimal NaCl concentration, at which the electrode effectively removed nitrate and produced as few byproducts as possible, was determined. Nitrate was completely removed using the Cu-Pd-TNPs electrode with a Pt anode at a NaCl concentration of 0.5 g L-1, little ammonia and almost no nitrite were detected in the treated solution. Using a constant current density, temperature strongly affected nitrate removal, but the initial nitrate concentration affected the removal rate little. Maximum nitrate was removed at pH 3 when the other conditions were constant.

Detection of type I collagen fibrils formation and dissociation by a fluorescence method based on thioflavin T.

In this study, fibrillogenesis and thermal dissociation of pepsin-soluble collagen (PSC), extracted from snakehead (Channa argus) skin, were monitored by fluorescence method based on thioflavin T (Th-T), where the accuracy and sensitivity were evaluated and compared with those of turbidity assay. The fluorescence method revealed the fibrillogenesis dynamics of collagen with better sensitivity, especially at nucleation and plateau stages. The melting temperature (Tm) of PSC was estimated to be 47°C by circular dichroism spectroscopy; below this temperature, the triple-helical structure should be intact. After that, the dynamic process of collagen dissociation was explored by the fluorescence method, and verified by morphological analysis of the fibrils and the proportion of retained fibrils. The thermal dissociation critical temperature (TDCT) of PSC fibrils was confirmed to be 39°C. The fluorescence intensity of fibril-incorporated Th-T gradually decreases in the dissociation process, and the decrease rate can be accelerated by increasing temperature. Finally, the thermal stability of triple-helical structures of free-, assembled- and dissociated-PSC was compared. Thus, we demonstrated the formation and thermal dissociation of collagen fibrils in vitro by a fluorescence method based on Th-T. This approach may advance the understanding of fibril formation and inverse dissociation of fish-sourced collagen in vitro.

Effect of ultrasonication on the fibril-formation and gel properties of collagen from grass carp skin.

Controlling the fibril-formation process of collagen in vitro to fabricate novel biomaterials is a new area in the field of collagen research. This study aimed to determine the effect of ultrasonication on collagen fibril formation and the properties of the resulting collagen gels. Native collagen, extracted from the skin of grass carp, self-assembled under ultrasonic conditions (at different ultrasonic power and duration). The self-assembly kinetics, fibrillar morphology, and physical and cell growth-promoting properties of the collagen gels were analyzed and compared. The results showed that the self-assembly rate of collagen was increased by ultrasonication at the nucleation stage. The resulting fibrils exhibited smaller diameters and D-periodicity lengths than that of the untreated collagen samples (p<0.05). The viscoelasticity and textural properties of collagen gels also changed after ultrasonication at the nucleation stage. Texture profile analysis and cell proliferation assays showed that ultrasonication produced softer collagen gel colloids, which were more suitable for cell proliferation than the untreated collagen gels.

Effect of heat treatment on the enzymatic stability of grass carp skin collagen and its ability to form fibrils in vitro.

BACKGROUND: The molecular configuration, molecular weight distribution and thermal transition enthalpy (ΔH) of grass carp skin (GCS) collagens after heat treatment under different conditions were measured using circular dichroism, gel filtration chromatography and differential scanning calorimetry (DSC). The enzymatic stability of collagen was evaluated using different enzymes, while the ability to form fibrils in vitro was assessed by morphological observation of collagen fibrils and turbidity testing. RESULTS: The ΔH values, in-solution molecular aggregation and the stability to enzymatic hydrolysis of GCS collagen decreased irreversibly and progressively with the duration of heat treatment at 33 °C, which was the onset endothermic temperature obtained from the DSC curve. A strong positive linear correlation between the enzymatic sensitivity of collagen and the degree of thermal denaturation was found. A decrease in fibril diameter and D-periodicity length with denaturation could also be observed in the SEM and TEM images. CONCLUSION: The onset endothermic temperature (To ) rather than the denaturation temperature (Td ) is the threshold temperature for configurational stability of GCS collagen in acidic solution, and the biological properties would obviously change if the collagen was heat treated at this temperature.

Effect of hematoporphyrin monomethyl ether-sonodynamic therapy (HMME-SDT) on hypertrophic scarring.

OBJECTIVE: The aim of the present study was to explore the potential for hematoporphyrin monomethyl ether-Sonodynamic Therapy (HMME-SDT) treatment of hypertrophic scars within rabbit ears. METHODS: 60 white rabbits were randomly divided into five groups: (1) untreated controls, (2) lesioned, (3) lesioned + HMME, (4) lesioned + US (Ultrasound), and (5) lesioned +HMME-SDT. After induction of a lesion upon the ears of the rabbits, hypertrophic scars were assessed at 14, 28, 42 and 56 days post-lesion +/- treatment. Assessments consisted of visual inspection in the change of the skin, scar formation pathological morphology by hematoxylin and eosin (HE) staining technique with optical microscopy, calculation of a hypertrophic index, fibroblastic density measures, and observation of collagen changes in the scar tissue by Van Gieson's (VG)Stain along with calculation of collagen area density. RESULTS: With continued HMME-SDT treatment there was a gradual improvement in all parameters over the duration of the experiment. The lesion-induced scars of rabbits receiving HMME-SDT treatment were soft, the size was reduced, hyperplasia was flat and the color pale. The fibroblasts and collagens were reduced and the collagens were light red, sparse and orderly. The hypertrophic index was reduced, since the fibroblastic density was lowered and collagen area density was decreased. CONCLUSION: HMME is an effective sonosensitizer and the combination of HMME-SDT treatment can exert significant benefits in reducing the formation of hypertrophic scars.

[Measurement of retinal nerve fiber layer thickness in Leber hereditary optic neuropathy by optical coherence tomography].

OBJECTIVE: To evaluate retinal nerve fiber layer (RNFL) thickness in patients and unaffected carriers of Leber hereditary optic neuropathy (LHON) by optical coherence tomography (OCT). METHODS: This case-control study enrolled 42 LHON maternal family members with mitochondrial DNA G11778A mutation and 100 normal volunteers. RNFL thickness was measured by Stratus OCT in each participant. Mean RNFL thickness of each quadrant, as well as 360° average were calculated and compared in normal controls, LHON carries and LHON patients. RESULTS: Among LHON maternal family members, 15 cases were unaffected carriers who were subgrouped as normal-fundus-appearing carriers (10 cases) and preclinical carriers (5 cases). Twenty seven LHON patients included 9, 5, and 13 cases in the early, advancing and advanced stages, respectively. Normal fundus-appearing carriers showed normal RNFL thickness of each quadrant and 360° average. Preclinical carriers and early-staged patients showed no significant difference in RNFL thickness of each quadrant and 360° average (P = 0.138 to 0.645), yet both showed thicker RNFL in temporal, superior and inferior quadrant, as well as 360° average, if compared with normal controls (P = 0.000 to 0.018). Compared with normal controls, preclinical carriers and early-staged patients, advancing LHON patients showed thinner RNFL in temporal and inferior quadrant, as well as 360° average (P = 0.000 to 0.005). Advanced LHON patients showed thinner RNFL in each quadrant and 360° average, compared with normal controls, LHON carriers, and advancing cases (P = 0.000 to 0.037). CONCLUSIONS: RNFL thickness in LHON patients and unaffected carriers was characterized by OCT in this study, which would improve the understanding of the natural course of LHON.

Shear thickening and jamming in densely packed suspensions of different particle shapes.

We investigated the effects of particle shape on shear thickening in densely packed suspensions. Rods of different aspect ratios and nonconvex hooked rods were fabricated. Viscosity curves and normal stresses were measured using a rheometer for a wide range of packing fractions for each shape. Suspensions of each shape exhibit qualitatively similar discontinuous shear thickening. The logarithmic slope of the stress vs shear rate increases dramatically with packing fraction and diverges at a critical packing fraction φ(c) which depends on particle shape. The packing fraction dependence of the viscosity curves for different convex shapes can be collapsed when the packing fraction is normalized by φ(c). Intriguingly, viscosity curves for nonconvex particles do not collapse on the same set as convex particles, showing strong shear thickening over a wider range of packing fraction. The value of φ(c) is found to coincide with the onset of a yield stress at the jamming transition, suggesting the jamming transition also controls shear thickening. The yield stress is found to correspond with trapped air in the suspensions, and the scale of the stress can be attributed to interfacial tension forces which dramatically increase above φ(c) due to the geometric constraints of jamming. Using this connection we show that the jamming transition can be identified by simply looking at the surface of suspensions. The relationship between shear and normal stresses is found to be linear in both the shear thickening and jammed regimes, indicating that the shear stresses come from friction. In the limit of zero shear rate, normal stresses pull the rheometer plates together due to the surface tension of the liquid below φ(c), but push the rheometer plates apart due to jamming above φ(c).

Generality of shear thickening in dense suspensions.

Suspensions are of wide interest and form the basis for many smart fluids. For most suspensions, the viscosity decreases with increasing shear rate, that is, they shear thin. Few are reported to do the opposite, that is, shear thicken, despite the longstanding expectation that shear thickening is a generic type of suspension behaviour. Here we resolve this apparent contradiction. We demonstrate that shear thickening can be masked by a yield stress and can be recovered when the yield stress is decreased below a threshold. We show the generality of this argument and quantify the threshold in rheology experiments where we control yield stresses arising from a variety of sources, such as attractions from particle surface interactions, induced dipoles from applied electric and magnetic fields, as well as confinement of hard particles at high packing fractions. These findings open up possibilities for the design of smart suspensions that combine shear thickening with electro- or magnetorheological response.

Blends of POSS-PEO(n=4)(8) and high molecular weight poly(ethylene oxide) as solid polymer electrolytes for lithium batteries.

Solid polymer electrolyte blends were prepared with POSS-PEO(n=4)8 (3K), poly(ethylene oxide) (PEO(600K)), and LiClO4 at different salt concentrations (O/Li = 8/1, 12/1, and 16/1). POSS-PEO(n=4)8/LiClO4 is amorphous at all O/Li investigated, whereas PEO(600K) is amorphous only for O/Li = 8/1 and semicrystalline for O/Li = 12/1 and 16/1. The tendency of PEO(600K) to crystallize limited the amount of POSS-PEO(n=4)(8) that could be incorporated into the blends, so that the greatest incorporation of POSS-PEO(n=4)(8) occurred for O/Li = 8/1. Blends of POSS-PEO(n=4)(8)/PEO(600K)/LiClO4 (O/Li = 8/1 and 12/1) microphase separated into two amorphous phases, a low T(g) phase of composition 85% POSS-PEO(n=4)(8)/15% PEO(600K) and a high T(g) phase of composition 29% POSS-PEO(n=4)(8)/71% PEO(600K). For O/Li = 16/1, the blends contained crystalline (pure PEO(600K)), and two amorphous phases, one rich in POSS-PEO(n=4)(8) and one rich in PEO(600K). Microphase, rather than macrophase separation was believed to occur as a result of Li(+)/ether oxygen cross-link sites. The conductivity of the blends depended on their composition. As expected, crystallinity decreased the conductivity of the blends. For the amorphous blends, when the low T(g) (80/20) phase was the continuous phase, the conductivity was intermediate between that of pure PEO(600K) and POSS-PEO(n=4)(8). When the high T(g) (70/30, 50/50, 30/70, and 20/80) phase was the continuous phase, the conductivity of the blend and PEO(600K) were identical, and lower than that for the POSS-PEO(n=4)(8) over the whole temperature range (10-90 degrees C). This suggests that the motions of the POSS-PEO(n=4)(8) were slowed down by the dynamics of the long chain PEO(600K) and that the minor, low Tg phase was not interconnected and thus did not contribute to enhanced conductivity. At temperatures above T(m) of PEO(600K), addition of the POSS-PEO(n=4)(8) did not result in conductivity improvement. The highest RT conductivity, 8 x 10(-6) S/cm, was obtained for a 60% POSS-PEO(n=4)(8)/40% PEO(600K)/LiClO4 (O/Li = 12/1) blend.