A contribution to borate crystal chemistry: Rules for the occurrence of polyborate anion types

The structural features of over 460 anhydrous oxoborates that are described in literature were analysed. Lewis acid strengths were calculated for all cations other than B3+ that were found in these structures, using the valences of the cations and their determined average coordination numbers. From the observation of a restriction of the occurrence of complex polyborate anions to specific ranges of cation Lewis acid strength in existing oxoborate compounds, the Lewis base strengths of the complex polyborate anions (not of the oxygen ligands) were inferred, using the idea that is at the bottom of the valence matching principle, that in the most stable compounds the Lewis acid strength of the cation nearly equals the Lewis base strength of the anion. From this, general inherent rules for the occurrence of the miscellaneous polyborate anions with respect to the ratio cation: boron (A:B), the Lewis acid strength(s) La of the cation(s) other than B3+ and the cation radii were developed. These rules offer the possibility for a prediction of the stoichiometry and the most probable polyborate structural group that will be adopted by a new anhydrous borate compound.

X-ray diffraction study of the piezoelectric properties of BiB3O6 single crystals

We have determined all eight components of the piezoelectric tensor of a monoclinic crystal, BiB3O6, by means of synchrotron X-ray diffraction technique. The experiments have been performed on a four circle goniometer using the ω-scan method introduced by Graafsma [1] which is universal in the choice of appropriate reflections. The determined values of the piezoelectric tensor are in good agreement with those obtained earlier for BiB3O6 with the use of an optical Michelson interferometer.

Neural network investigation of borate crystal properties

Correlations between crystal chemical properties of anhydrous oxoborate crystals wereanalysed using artificial neural networks. Using structuralproperties of oxoborate crystal structures described inthe literature, we developed several neural network modelsthat capture statistical relations between crystalchemical properties of the anhydrous oxoborates from the existingdata sets. This indicates the suitability of neural networks forthe prediction of structural propertiesof crystals.

The lanthanum(III) molybdate(VI) La4Mo7O27

Crystals of the ortho­rhom­bic phase La₄Mo₇O₂₇ (lanthanum molybdenum oxide) were obtained from a non-stoichiometric melt in the pseudo-ternary system La₂O₃–MoO₃–B₂O₃. In the crystal structure, distorted square-anti­prismatic [LaO₈] and monocapped square-anti­prismatic [LaO₉] polyhedra are connected via common edges and faces into chains along [010]. These chains are arranged in layers that alternate with layers of [MoO₄] and [MoO₅] polyhedra parallel to (001). In the molybdate layers, a distorted [MoO₅] trigonal bipyramid is axially connected to two [MoO₄] tetra­hedra, forming a [Mo₃O₁₁] unit.

Simultaneous subsecond hyperpolarization of the nuclear and electron spins of phosphorus in silicon by optical pumping of exciton transitions

We demonstrate a method which can hyperpolarize both the electron and nuclear spins of 31P donors in Si at low field, where both would be essentially unpolarized in equilibrium. It is based on the selective ionization of donors in a specific hyperfine state by optically pumping donor bound exciton hyperfine transitions, which can be spectrally resolved in 28Si. Electron and nuclear polarizations of 90% and 76%, respectively, are obtained in less than a second, providing an initialization mechanism for qubits based on these spins, and enabling further ESR and NMR studies on dilute 31P in 28Si.

Subcutaneous or intravenous administration of romiplostim in thrombocytopenic patients with myelodysplastic syndrome (MDS)

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Background: Thrombocytopenia is common in patients (pts) with MDS, and treatment options are currently limited to platelet (plt) transfusions. Romiplostim is an Fc-peptide fusion protein (peptibody) that stimulates plt production by the same mechanism as thrombopoietin. Methods: This was a phase II, multicenter, single arm, open-label study. Eligibility criteria included IPSS low or intermediate-1 risk MDS and a mean baseline plt count ≤50x109/L. Safety and efficacy of romiplostim were evaluated in pts receiving 750μg romiplostim according to one of 3 schedules: weekly or biweekly subcutaneous injections (QWSC or Q2WSC), or biweekly intravenous injections (Q2WIV). Plt responses were measured per IWG 2006 criteria. Results: Of the 28 pts enrolled, 17 (61%) completed the study; 22 (79%) were male and the mean (±SD) baseline plt count was 29 (±10) x 109/L. The mean age was 71 years and 19 pts (68%) had received plt transfusions in the past year. Mean duration of exposure to romiplostim was 12 (±8) weeks. The most common adverse events (AEs) were fatigue and headache (both 18%). Five pts experienced serious AEs, and there were 2 cases of disease progression to AML: one pt in the QWSC cohort who received romiplostim for 4 weeks and one in the Q2WSC cohort who received romiplostim for 20 weeks. For pts who completed 8 weeks treatment, 15/23 (65%) achieved a plt response, defined by IWG 2006 criteria, and 14/23 (61%) did not require a plt transfusion during this period. The small number of pts limited the ability to compare administration schedules; minor differences were observed in plt responses and plt transfusions, and the incidence of AEs appeared similar among cohorts. Conclusions: IV and SC romiplostim appeared well-tolerated and effective in raising plt counts and avoiding plt transfusions in low and intermediate-1 risk MDS pts. The dose recommendation for future studies is 750μg, given QW or Q2W SC.

[Table: see text]

[Table: see text]

Observation and coupling of domains in a spin-spiral multiferroic

The coexistence, coupling, and manipulation of magnetic spiral domains and magnetically induced ferroelectric domains are spatially resolved by optical second harmonic generation in multiferroic MnWO4. Eight types of magnetic domains couple to two ferroelectric domains. An electric field uniquely creates a magnetic single-domain state. A magnetic field quenches the spontaneous polarization while retaining its magnetic origin so that the ferroelectric domains are concealed instead of destroyed.

The effects of isometric exercises and stretching on postural stability in Non–Insulin Dependent Diabetes Mellitus patients with diffuse symmetrical sensory motor neuropathy

The purpose of this study was to explore the effects of isometric exercises and stretching on postural stability in Non – Insulin Dependent Diabetes Mellitus (NIDDM) patients with diffuse symmetrical sensory motor neuropathy. Patients were assigned to an experimental group and amatched control group. The experimental group received isometric exer-cises and stretching three times weekly for 12 weeks in addition to routine medication and dietary advice. A t the end of this period, this group wascompared with the control group, which received routine medication anddietary advice only. Measurements of muscle strength of quadriceps, ham-strings, ankle plantar and dorsiflexors, and Romberg’s test for postural sta-bility were carried out before and after the 12 weeks intervention. The study showed that isometric exercises and stretching for the lower extremities improved postural stability (p = 0.00)and strength of the quadriceps (p = 0.001) hamstrings (p = 0.001) dorsiflexors (p = 0.001) plantarflexors (p = 0.001)in NIDDM patients with diffuse symmetrical sensory motor neuropathy. This exercise regimen also had a loweringeffect on blood glucose level (p = 0.00).  In conclusion it seems that the simple exercise intervention described in thisstudy may be of benefit to these patients if incorporated into their management programmes.

The effect of exercising with manual compression foot pumps, on dialysis efficiency, in patients with end stage renal disease

Aim: This study aimed to establish if exercising with manual compressionfoot-pumps, could be used as an intervention to improve dialysis efficacy. A  pre test -post test design was used to test the intervention. Subjects were invited to participate in the study depending on whether they fitted the eligibility criteria of the study. Eight weeks after entry into the study pre-test values of dialysis efficacy (Kt/V ) were established prior to the implementation of an eight-week exercise programme followed by the collection of post intervention dialysis efficacy values. Subjects performed seated heel raises with manual compression foot-pumps on their feet (Venous A nti-stasis Slippers) for 20 continuous minutes per hour for the first three hours of their dialysis sessions (two or three times per week). Twelve subjects finished the programme. During the eight weeks of exercise an increaseof 8.7% was noted in Kt/V  values with a mean change of 0.12 (p=0.04). It appears that an eight week exercise programme using manual compression foot pumps (Venous A nti-stasis Slippers) may be effective in improving dialysisefficiency. These findings need to be tested in a study with an appropriate sample size.

Tswana speaking South Africans’ understanding of pain scales

Aim: The aim of this study was to establish the validity and reliability of the Tswanatranslations of three pain scales.Design: This was a cross–sectional study to validate and test the reliability of threepain scales.Participants:   One hundred subjects participated in the study. They were selectedfrom the back schools of five hospitals in the North -West Province of South A frica andfrom workers in these hospitals who were employed as kitchen workers, laundryworkers and cleaners.Method: Translation of the pain scales and the stages of cross-cultural adaptation were followed as recommended byBeaton et al (2000). Pain tolerance of the subjects was measured using a P.T.M. (pressure threshold meter). The painscales used were the V.A .S. (visual analogue scale) one (nought and ten only), the V.A .S. (visual analogue scale) two(nought through to ten), the W.B.F. (Wong-Baker Faces pain measure) and the V.R.S. (verbal rating scale).  The V.R.S.used came in two forms. The first form was written on cue cards which the subjects arranged in order and the second form was the questionnaire version of the V.R.S.The subjects were interviewed and asked five questions relating to their back pain. Upon completion of the interviewthe pressure threshold of the painful area (back) was tested. Subjects then filled in the three pain scales, namely the (V.A .S. one, V.A .S. two, the V.R.S. and lastly the W.B.F. pain scale). Approximately a third of the sample (37) was retested the following day following the same procedure asdescribed above. Results: There was no correlation between the pressure threshold meter readings and the pain scale measurements.  Conclusion: From the statistical analysis of the results, it became apparent that the subjects tested did not have anunderstanding of any of the three pain scales. Future research needs to be done in developing entirely different scales for peoples of low literacy and differentlanguage and cultural groups in South Africa.

Polarised IR and Raman spectra of non-centrosymmetric Na3Li(SeO4)2.6H2O crystal--a new Raman laser material

Polarised IR and Raman spectra of Na3Li(SeO4)2.6H2O single crystal have been recorded. Discussion of the results has been based on the factor group approach for the trigonal R3c (C3v6) space group with Z = 2. The obtained results for the spontaneous Raman scattering have been used in the discussion of the stimulated Raman spectra of the material studied--a new Raman laser crystal.

Effect of penetrating trunk trauma on the recovery of adult survivors: a pilot study

Gunshot and/or stab wounds to the trunk are injuries seen in South African hospitals. Patients are managed in the intensive care unit. Prolonged mechanical ventilation with immobilization results in some degree of muscle dysfunction. Our goal was to determine if patients recover adequately spontaneously following critical illness. No formal rehabilitation programmes exist in South Africa for these patients following discharge. A prospective, observational study was conducted. Patients were recruited from three ICUs in Johannesburg. Lung function tests, dynamometry, quality of life, 6-minute-walk, and oxygen uptake tests were performed over 6 months following discharge from the hospital. The control group consisted of existing data for healthy volunteers. Distance walked during 6-minute-walk test was significantly reduced for the study group compared to the control group (1 month [p = 0.00251]; 6 months [p = 0.0355]). At 1 month there was a significant reduction in quadriceps and triceps strength for the study group compared to the control group (p = 0.0089; p = 0.0246, respectively). Quadriceps strength remained significantly reduced for the study group (3 months [p = 0.0489]). No difference in muscle strength was detected between the groups at 6 months. Actual and predicted residual volumes differed significantly for the study group (1 month [p = 0.0034]; 6 months [p = 0.0157]). A trend of muscle weakness (to 3 months), poor exercise capacity, and abnormal lung volumes was identified. A formal rehabilitation programme may be needed to address these disabilities.

Dipraseodymium(III) pyroborate molybdate(VI), Pr(2)(B(2)O(5))(MoO(4))

Single crystals of triclinic Pr₂(B₂O₅)(MoO₄) were prepared from an incongruently melting flux in the system Pr₂O₃–MoO₃–B₂O₃ in a platinum crucible in an atmosphere of air. In the crystal structure, distorted edge-sharing [PrO₈] square anti­prisms form a three-dimensional framework. These are further linked by isolated [MoO₄] tetra­hedra and isolated pyroborate groups [B₂O₅], the latter consisting of two independent trigonal [BO₃] groups sharing one O atom. The [MoO₄] tetra­hedra and the [B₂O₅] groups are arranged in alternating layers parallel to the ab plane.

Dineodymium(III) ditungstate(VI), Nd(2)W(2)O(9)

Single crystals of monoclinic Nd₂W₂O₉ were obtained by growth from tungsten borate flux in an atmosphere of air. The crystal structure consists of chains of distorted [WO₆] octa­hedra that run along the c axis of the structure, and of [NdO₉] polyhedra that are connected via common faces and common edges to form a three-dimensional framework.

Reduction of the linewidths of deep luminescence centers in 28Si reveals fingerprints of the isotope constituents

Dramatic reductions of the linewidths of well-known deep centers in 28Si reveal "isotopic fingerprints" of the constituents. The approximately 1014 meV Cu center, thought to be either a Cu pair or an isolated Cu, is shown to contain four Cu atoms, and the approximately 780 meV Ag center is shown to contain four Ag. The approximately 944 meV ;{*}Cu center, thought to be a different configuration of a Cu pair, in fact contains three Cu and one Ag, and a new two-Cu two-Ag center is found. The approximately 735 meV center, previously assigned to Fe, actually contains Au and three Cu. This suggests a family of four-atom (Cu, Ag, Au) centers.