Exploitation of mica deposits at Nellore mica belt, Andhra Pradesh, India

India is the leading producer of sheet mica and a major part of this is exported. Nellore mica belt is the largest mica-producing area covering part of Nellore district in Andhra Pradesh, India. As most of the mines are old and privately operated, they are developed and operated purely based on local experiences. In this article, we highlight the problems associated with the present mica-mining practices in the Nellore mica belt, and scientific approaches that have been adopted for fixing different parameters associated with mica extraction. Based on detailed field study, geo-mechanical data and tested rock properties, extensive numerical modelling is done to suggest the best possible method of mining for safe and sustainable mica extraction from the area

PROCESS VALIDATION OF BETA-SITOSTEROL HAIR GEL FORMULATION AND EVALUATION OF 5 ALPHA REDUCTASE INHIBITION IN VITRO FOR THE TREATMENT OF ANDROGENETIC ALOPECIA

Objective: The present study was aimed to develop topical gel containing β-sitosterol using carbopol 940 as gelling agent and to investigate 5 alpha reductase (5α-reductase) inhibitory activity of suitable gel formulation and compare it with a commercial product used topically for alopecia. Methods: Three different batches of β-sitosterol hair gel formulation were manufactured and evaluated. Additionally, the 5α-reductase inhibitory activity of the prepared formulation, finasteride as a positive control, was evaluated and compared to the commercial herbal formulation used. Results: According to the analytical findings of three different batches, the gel formulation is good in appearance, homogeneous, and easily spreadable. Based on findings from HPLC and HPTLC, the amount of β-sitosterol in those formulations complies with the label claim. By checking different critical parameters of those batches, we established the manufacturing process method validation and the process reproducibility. In-vitro results showed the good 5α-reductase inhibitory potential of prepared gel formulation and then commercial product. The IC50 value of the prepared formulation was 118.960 ± 0.634 (µg/ml) and standard beta-sitosterol 88.854 ± 0.70 (µg/ml), whereas Finasteride (positive control) 224.372 ± 3.103 (ng/ml). Conclusion: Thus, β-sitosterol formulation utilises a straightforward, low-cost production, less time-consuming process with minimal facility and equipment requirements. The formulation may be a promising candidate for future investigation into their antiandrogenic activities

Understanding the drug delivery through nails: a comprehensive review

The nail unit is the largest cutaneous musculo-skeletal appendage. The management of nail disorders is an onerous task owing to the disease manifestations and anatomical structure of the nail plate. The topical treatment of nail infections/disorders has been a centerpiece of nail research in the past few decades as it offers a much safer and focused alternative to conventional oral therapy. However, transungual delivery had its challenges. This necessitated a lookout for novel approaches that enhanced treatment efficacy and reduced treatment time. Moreover, curing the nail condition using topical delivery has been challenging due to the lack of a validated animal model to determine the efficacy of the formulation and to establish a mathematical model that can help in predicting the desirable attributes of the formulation and permeation of various molecules through the nail plate. This review is based on publications retrieved by a selective search in PubMed. The purpose of this review is to provide an overview of nail anatomy and its disorders, factors affecting nail delivery, diagnostic procedures, current approaches, and promising approaches to treat nail infections/disorders including nail lacquers and the role of permeation enhancers, in-vitro models. This review also covers current available treatments and treatments under clinical trial. Keywords: Musculo-skeletal, Nail infection, Transungual, Mathematical model, In-vitro models

Assessment of roof convergence during driving roadways in underground coal mines by continuous miner

In India, a number of coal seams are being extracted by using the continuous miner (CM). There is a need to standardise some of the major parameters like cut-out distance (COD) and the convergence of the roof strata for safe operation of the CM. The production and productivity of this system mainly depend on the COD, i.e. the length of the stable drivage made in the coal seam by the CM at a time without installing any reinforcement/support. This factor is determined by assessing the convergence of the roof strata. Therefore, prior to driving of the roadways by the CM, the estimation of the convergence of the roof strata is necessary for safe and stable driving of the roadways. No suitable empirical relationship is found between the convergence and the COD. This paper deals with the assessment of the roof convergence during development of the coal seams by the CM. Variations of the convergence with the major influencing parameters, i.e. the COD, the rock mass rating and the width of the gallery, are obtained by the parametric study through elasto-plastic numerical modelling. The trend of the convergence data with respect to the input parameters is found non-linear. Thus, a non-linear multivariate model is framed by putting the constant and exponents in the input parameters. These constant and exponents are determined through regression analysis to develop a predictive model. The coefficient of determination of the model is around 0.98. The model is validated with the monitoring data of different mines. This model can be applied for the assessment of the convergence of the roof in underground coal mines for safe driving of the roadways by the CM. Alternatively, optimum COD of the CM can be designed by fixing the threshold limit of the convergence value for a particular geomining condition

Probabilistic stability analysis of failed and stable cases of coal pillars

The conventional design criterion of the safety factor for pillar stability is a deterministic approach characterised by non-random and exact values of its input parameters i.e. strength and stress. The integrity of pillars often jeopardized when some fluctuations or deviations occur in their strength and stress due to uncertainties in field conditions. To counter these unknown fluctuations or deviations, the coal pillars are designed with safety factors greater than unity and their exact values are selected based on local geomining factors. This practice does not guarantee stability against the geomining uncertainties and consequently lock-up the coal in the bigger size of the pillars. Therefore, to assess the variability in the input parameters in pillar design, this paper presents a probabilistic approach to analyse the stability of coal pillars considering the cases of stable and failed pillars in Indian coalfields. The databases of input design parameters are collected for stable and failed coal pillars from different Indian coal mines. The probabilistic distribution fittings of strengths, stresses and safety factors of stable flat, stable inclined, failed flat and failed inclined pillar cases are derived to know their means and standard deviations. The Monte Carlo Simulation and the First Order Reliability Method have been implemented to solve the limit state functions. The failure probabilities estimated for stable flat, stable inclined, failed flat and failed inclined cases are 0.29, 0.28, 0.56, and 0.99 respectively. The analysis recommends the safety factors of corresponding threshold failure probabilities of stable flat pillars as 1.61 and for stable inclined pillars as 1.41 in Indian mines with the ranges of design parameters considered in their databases. Therefore, the probabilistic stability analysis can provide an additional design criterion to select the optimum safety factor of pillars for improved recovery rates in coal mines

Stability Evaluation of Old and Unapproachable Underground Mine Workings below Surface Structures

There are many places in the different countries of the world where working in the underground mines have been done below surface structures such as railway lines, roads, buildings, villages/residential colonies, pipelines, etc. The workings are generally old, abandoned and presently unapproachable. In some places, important delicate surface structures are installed above a portion of old abandoned underground workings. Safety of these important surface structures above old underground mine workings is a serious concern in many countries all over the world. Many times, it is difficult to move or divert these surface structures due to a number of reasons including technical problems, the involvement of huge expenditures and socio-economic issues. There is a need to assess the stability of these places and the procedure to stabilise the places if found unstable to make the structures safe. Hence, there is a need of proper stability assessment of the ground below these surface structures. The railway line is one of such important structures, where stability should be ensured for the safety of the passengers. In India, many underground workings are present below railway lines. Most of the workings are old and unapproachable and their stability status is in doubt. Dismantling or diverting of the important railway lines is a high-level policy matter and involves huge time and money besides complicated socio-political issues like the rehabilitation of the affected people. But the safety of the commuters using railways passing over the coal-bearing areas having mining activities cannot be compromised. Therefore, it is highly preferable to take protective measures instead of dismantling and diversion of lines, wherever possible. It is necessary to establish the position and dimension of the inaccessible underground workings below these types of important surface structures and carry out its stability analysis to take appropriate protective measures for the safety of the structures and commuters. This paper highlights the delineation procedure of the unapproachable underground roadways below surface structures with special reference to railway lines and its stability evaluation with case studies. Appropriate protective measures have also been suggested which are proved to be effective and validated the results of the study

Evaluation of Stability of underground workings for exploitation of an inclined coal seam by the ubiquitous joint model

The effect of the inclination of strata and the coal seam on the stability of surrounding rock masses is evaluated by parametric study through numerical modelling. The ubiquitous joint model is used to consider the shearing effect of the bedding planes. The rock load height above the galleries is estimated by calculating the safety factor of immediate roof. It is obtained from the study that the rock load height and stress concentration are comparatively more at the dip side of the working than the rise side. The pillar strength is minimum when the inclination of the coal seam is close to (π/4 + ϕ /2) j where ϕj is the friction angle of the bedding plane. A case study of inclined Jarangdih new seam (10' seam) of Sawang Colliery of Central Coalfields Limited (CCL) in India is presented. The inclination of the coal seam is around 1 in 3. As the coal seam is developed along the apparent dip of 1 in 5, the coal pillars become rhombus shaped with acute angle of 40°. Both numerical modelling and field investigation reveal that the failure zone extends more toward the acute angle of the coal pillar. Thus, heavier support system is installed in the roof at the intersections near acute angles of the coal pillars. Support system is designed based on the rock load height. Extraction methodology including stability analysis has also been presented for depillaring of this inclined coal seam

Evaluation of energy accumulation, strain burst potential and stability of rock mass during underground extraction of a highly stressed coal seam under massive strata-a field study

Severe geotechnical problems like strain burst, side spalling, roof fall, irregular caving, the premature collapse of rib/remnant pillars, etc. are frequently observed during the mining of highly stressed coal seams under massive overlying strata. In this study, different underground structures and adequate support systems under such complex geological conditions are designed by evaluating energy accumulation, strain burst potential, stress conditions and stability of the rock mass. An energy-based safety factor is derived and implemented through numerical modelling to identify the yield zones in the surrounding rock mass. The strain burst potential in different locations is also evaluated by the elastic energy accumulation and the Burst Potential Index (BPI) whose maximum values reach 628 kJ/m3 and 47.6% respectively during depillaring operations. These values indicate the significant strain burst and side spalling conditions which are corroborated by the field investigations and monitoring data by geotechnical instruments. Control measures have been taken by leaving the optimum size of rib/remnant pillars in the goaf and installing adequate support systems in the working areas. It is observed in the field that rib/remnant pillars, designed with a safety factor of ∼0.17 are found suitable for regular caving of overlying massive strata in the goaf. The side spalling and the strain burst are minimised by installing the glass-reinforced plastic (GRP) bolts and the wire mesh. The uncontrolled caving of the overlying massive strata in the working area is prevented by installing closely spaced two rows of rock bolts at the goaf edge. This study would be helpful to design different underground structures and to ensure the safety of working areas during the extraction of highly stressed coal seams under massive strata