The molecular structure of the borate mineral inderite Mg(H4B3O7)(OH)⋅5H2O – A vibrational spectroscopic study

We have undertaken a study of the mineral inderite Mg(H4B3O7)(OH)⋅5H2O a hydrated hydroxy borate mineral of magnesium using scanning electron microscopy, thermogravimetry and vibrational spectroscopic techniques. The structure consists of [B3O3(OH)5]2-[B3O3(OH)5]2- soroborate groups and Mg(OH)2(H2O)4 octahedra interconnected into discrete molecules by the sharing of two OH groups. Thermogravimetry shows a mass loss of 47.2% at 137.5 °C, proving the mineral is thermally unstable. Raman bands at 954, 1047 and 1116 cm−1 are assigned to the trigonal symmetric stretching mode. The two bands at 880 and 916 cm−1 are attributed to the symmetric stretching mode of the tetrahedral boron. Both the Raman and infrared spectra of inderite show complexity. Raman bands are observed at 3052, 3233, 3330, 3392 attributed to water stretching vibrations and 3459 cm−1 with sharper bands at 3459, 3530 and 3562 cm−1 assigned to OH stretching vibrations. Vibrational spectroscopy is used to assess the molecular structure of inderite.

Vibrational spectroscopy of the borate mineral gaudefroyite Ca4Mn3+3-x(BO3)3(CO3)(O,OH) from N’Chwaning II mine, Kalahari, Republic of South Africa

Gaudefroyite Ca4Mn3+3-x(BO3)3(CO3)(O,OH)3 is an unusual mineral containing both borate and carbonate groups and is found in the oxidation zones of manganese minerals, and it is black in color. Vibrational spectroscopy has been used to explore the molecular structure of gaudefroyite. Gaudefroyite crystals are short dipyramidal or prismatic with prominent pyramidal terminations, to 5 cm. Two very sharp Raman bands at 927 and 1076 cm-1are assigned to trigonal borate and carbonate respectively. Broad Raman bands at 1194, 1219 and 1281 cm-1 are attributed to BOH in-plane bending modes. Raman bands at 649 and 670 cm-1 are assigned to the bending modes of trigonal and tetrahedral boron. Infrared spectroscopy supports these band assignments. Raman bands in the OH stretching region are of a low intensity. The combination of Raman and infrared spectroscopy enables the assessment of the molecular structure of gaudefroyite to be made.

Vibrational spectroscopy of the borate mineral chambersite MnB7O13Cl – Implications for the molecular structure

Chambersite is a manganese borate mineral with formula: MnB7O13Cl and occurs as colorless crystals in the monoclinic pyramidal crystal system. Raman bands at 902, 920, 942 and 963 cm-1 are assigned to the BO stretching vibration of the B7O13 units. Raman bands at 1027, 1045, 1056, 1075 and 1091 cm-1 are attributed to the BCl in-plane bending modes. The intense infrared band at 866 cm-1 is assigned to the trigonal borate stretching modes. The Raman band at 660 cm-1 together with bands at 597, 642 679, 705 and 721 cm-1 are assigned to the trigonal and tetrahedral borate bending modes. The molecular structure of a natural chambersite has been assessed using vibrational spectroscopy.

Infrared and Raman spectroscopic characterization of the borate mineral hydroboracite CaMg[B3O4(OH)3]2⋅3H2O : implications for the molecular structure

We have studied the mineral hydroboracite CaMg[B3O4(OH)3]2∙3H2O using electron microscopy and vibrational spectroscopy. Both tetrahedral and trigonal boron units are observed. The nominal resolution of the Raman spectrometer is of the order of 2 cm-1 and as such is sufficient enough to identify separate bands for the stretching bands of the two boron isotopes. The Raman band at 1039 cm-1 is assigned to BO stretching vibration. Raman bands at 1144, 1157, 1229, 1318 cm-1 are attributed to the BOH in-plane bending modes. Raman bands at 825 and 925 cm-1 are attributed to the antisymmetric stretching modes of tetrahedral boron. The sharp Raman peak at 925 cm-1 is from the 11-B component such a mode, then it should have a smaller 10-B satellite near (1.03)x(925) = 952 cm-1, and indeed a small peak at 955 is observed. Four sharp Raman bands observed at 3371, 3507, 3563 and 3632 cm-1 are attributed to the stretching vibrations of hydroxyl units. The broad Raman bands at 3076, 3138, 3255, 3384 and 3551 cm-1 are assigned to water stretching vibrations. Infrared bands at 3367, 3505, 3559 and 3631 cm-1are assigned to the stretching vibration of the hydroxyl units. Broad infrared bands at 3072 and 3254 cm-1 are assigned to water stretching vibrations. Infrared bands at 1318, 1349, 1371, 1383 cm-1 are assigned to the antisymmetric stretching vibrations of trigonal boron

Vibrational spectroscopy of the borate mineral tunellite SrB6O9(OH)2·3(H2O) : implications for the molecular structure

Tunellite is a strontium borate mineral with formula: SrB6O9(OH)2∙3(H2O) and occurs as colorless crystals in the monoclinic pyramidal crystal system. An intense Raman band at 994 cm-1 was assigned to the BO stretching vibration of the B2O3 units. Raman bands at 1043, 1063, 1082 and 1113 cm-1 are attributed to the in-plane bending vibrations of trigonal boron. Sharp Raman bands observed at 464, 480, 523, 568 and 639 cm-1 are simply defined as trigonal and tetrahedral borate bending modes. The Raman spectrum clearly shows intense Raman bands at 3567 and 3614 cm-1, attributed to OH units. The molecular structure of a natural tunellite has been assessed by using vibrational spectroscopy.

Containing Queensland prickly pear : buffer zones, closer settlement, whiteness

By 1925, the introduced prickly pear (Opuntia and Nopalea spp.) covered up to 60 million acres of Queensland and New South Wales in what was perceived as prime agricultural land. After 40 years of experimentation, all Queensland Government strategies had failed. Faced with this failure and a diminishing expectation that the land would ever be conquered, buffer zones were proposed by the newly formed Queensland Prickly Pear Land Commission. A close reading of government documents, newspaper reports and local histories about these buffer zones shows how settler anxieties over who could or should occupy the land shaped the kinds of strategies recommended and adopted in relation to this alien species. Physical and cultural techniques were used to manage the uneasy coexistence between prickly pear, on the one hand, and farmers and graziers on the other. Furthermore, this environmental history challenges the notion of racially homogenous closer settlement under the White Australia Policy, showing the many different kinds of livelihood and labour in prickly pear land in the 1920s.

The impact of neighborhood walkability on walking : does it differ across adult life stage and does neighborhood buffer size matter?

We explored the impact of neighborhood walkability on young adults, early-middle adults, middle-aged adults, and older adults' walking across different neighborhood buffers. Participants completed the Western Australian Health and Wellbeing Surveillance System Survey (2003–2009) and were allocated a neighborhood walkability score at 200 m, 400 m, 800 m, and 1600 m around their home. We found little difference in strength of associations across neighborhood size buffers for all life stages. We conclude that neighborhood walkability supports more walking regardless of adult life stage and is relevant for small (e.g., 200 m) and larger (e.g., 1600 m) neighborhood buffers.

The molecular structure of the borate mineral rhodizite (K, Cs)Al4Be4(B, Be)12O28 – A vibrational spectroscopic study

We have studied the borate mineral rhodizite (K, Cs)Al4Be4(B, Be)12O28 using a combination of DEM with EDX and vibrational spectroscopic techniques. The mineral occurs as colorless, gray, yellow to white crystals in the triclinic crystal system. The studied sample is from the Antandrokomby Mine, Sahatany valley, Madagascar. The mineral is prized as a semi-precious jewel. Semi-quantitative chemical composition shows a Al, Ca, borate with minor amounts of K, Mg and Cs. The mineral has a characteristic borate Raman spectrum and bands are assigned to the stretching and bending modes of B, Be and Al. No Raman bands in the OH stretching region were observed.

Infrared and Raman spectroscopic characterization of the Borate mineral Vonsenite

There are a large number of boron-containing minerals, of which vonsenite is one. Some discussion about the molecular structure of vonsenite exists in the literature. Whether water is involved in the structure is ill-determined. The molecular structure of vonsenite has been assessed by the combination of Raman and infrared spectroscopy. The Raman spectrum is characterized by two intense broad bands at 997 and 1059 cm−1 assigned to the BO stretching vibrational mode. A series of Raman bands in the 1200–1500 cm−1 spectral range are attributed to BO antisymmetric stretching modes and in-plane bending modes. The infrared spectrum shows complexity in this spectral range. No Raman spectrum of water in the OH stretching region could be obtained. The infrared spectrum shows a series of overlapping bands with bands identified at 3037, 3245, 3443, 3556, and 3614 cm−1. It is important to understand the structure of vonsenite in order to form nanomaterials based on its structure. Vibrational spectroscopy enables a better understanding of the structure of vonsenite.

Power buffer with model predictive control for stability of vehicular power systems with constant power loads

Electrification of vehicular systems has gained increased momentum in recent years with particular attention to constant power loads (CPLs). Since a CPL potentially threatens system stability, stability analysis of hybrid electric vehicle with CPLs becomes necessary. A new power buffer configuration with battery is introduced to mitigate the effect of instability caused by CPLs. Model predictive control (MPC) is applied to regulate the power buffer to decouple source and load dynamics. Moreover, MPC provides an optimal tradeoff between modification of load impedance, variation of dc-link voltage and battery current ripples. This is particularly important during transients or starting of system faults, since battery response is not very fast. Optimal tradeoff becomes even more significant when considering low-cost power buffer without battery. This paper analyzes system models for both voltage swell and voltage dip faults. Furthermore, a dual mode MPC algorithm is implemented in real time offering improved stability. A comprehensive set of experimental results is included to verify the efficacy of the proposed power buffer.

A vibrational spectroscopic study of the borate mineral takedaite Ca3(BO3)2

We have studied the mineral takedaite Ca3(BO3)2, a borate mineral of calcium using SEM with EDX and vibrational spectroscopy. Chemical analysis shows a homogeneous phase, composed of Ca. Boron was not detected. A very intense Raman band at 1087 cm−1 is assigned to the BO stretching vibration of BO3 units. Additional Raman bands may be due to isotopic splitting. In the infrared spectrum, bands at 1218 cm−1 and at 1163, 1262 and 1295 cm−1 are assigned to the trigonal borate stretching modes. Raman bands at 712 and 715 cm−1 are assigned to the in-plane bending modes of the BO3 units. Vibrational spectroscopy enables aspects of the molecular structure of takedaite to be assessed.

Determination of battery storage capacity in energy buffer for wind farm

Design of a battery energy storage system (BESS) in a buffer scheme is examined for the purpose of attenuating the effects of unsteady input power from wind farms. The design problem is formulated as maximization of an objective function that measures the economic benefit obtainable from the dispatched power from the wind farm against the cost of the BESS. Solution to the problem results in the determination of the capacity of the BESS to ensure constant dispatched power to the connected grid, while the voltage level across the dc-link of the buffer is kept within preset limits. A computational procedure to determine the BESS capacity and the evaluation of the dc voltage is shown. Illustrative examples using the proposed design method are included.

Buffer scheme with battery energy storage capability for enhancement of network transient stability and load ride-through

This paper examines a buffer scheme to mitigate the negative impacts of power-conditioned loads on network voltage and transient stabilities. The scheme is based on the use of battery energy-storage systems in the buffers. The storage systems ensure that protected loads downstream of the buffers can ride through upstream voltage sags and swells. Also, by controlling the buffers to operate in either constant impedance or constant power modes, power is absorbed or injected by the storage systems. The scheme thereby regulates the rotor-angle deviations of generators and enhances network transient stability. A computational method is described in which the capacity of the storage systems is determined to achieve simultaneously the above dual objectives of load ride-through and stability enhancement. The efficacy of the resulting scheme is demonstrated through numerical examples.

On the design of power buffer and its applications

A power electronics-based buffer is examined in which through control of its PWM converters, the buffer-load combination is driven to operate under either constant power or constant impedance modes. A battery, incorporated within the buffer, provides the energy storage facility to facilitate the necessary power flow control. Real power demand from upstream supply is regulated under fault condition, and the possibility of voltage or network instability is reduced. The proposed buffer is also applied to a wind farm. It is shown that the buffer stabilizes the power contribution from the farm. Based on a battery cost-benefit analysis, a method is developed to determine the optimal level of the power supplied from the wind farm and the corresponding capacity of the battery storage system.

Vibrational spectroscopy of the borate mineral priceite : implications for the molecular structure

Priceite is a calcium borate mineral and occurs as white crystals in the monoclinic pyramidal crystal system. We have used a combination of Raman spectroscopy with complimentary infrared spectroscopy and scanning electron microscopy with Energy-dispersive X-ray Spectroscopy (EDS) to study the mineral priceite. Chemical analysis shows a pure phase consisting of B and Ca only. Raman bands at 956, 974, 991, and 1019 cm−1 are assigned to the BO stretching vibration of the B10O19 units. Raman bands at 1071, 1100, 1127, 1169, and 1211 cm−1 are attributed to the BOH in-plane bending modes. The intense infrared band at 805 cm−1 is assigned to the trigonal borate stretching modes. The Raman band at 674 cm−1 together with bands at 689, 697, 736, and 602 cm−1 are assigned to the trigonal and tetrahedral borate bending modes. Raman spectroscopy in the hydroxyl stretching region shows a series of bands with intense Raman band at 3555 cm−1 with a distinct shoulder at 3568 cm−1. Other bands in this spectral region are found at 3221, 3385, 3404, 3496, and 3510 cm−1. All of these bands are assigned to water stretching vibrations. The observation of multiple bands supports the concept of water being in different molecular environments in the structure of priceite. The molecular structure of a natural priceite has been assessed using vibrational spectroscopy.