Revival of Complementary and Alternative Herbal Medicines

Herbal medicines, complementary or alternative medicines is a wide term for the therapies that are not part of standard care but it has many theories regarding efficacy based on personal experiences, history and common knowledge. It has long been used since ancient times since the beginning of human civilization. Its use had caught much attention in the early 1800s, with the development in the science of chemistry, a new era in pharmacotherapeutics and the use of active chemical ingredients in plants which were known to produce favorable therapeutic effects, were explored, active compounds were extracted, purified and their structure was revealed. This advancement paved the way towards modern pharmaceutical therapy. The modern drugs are based on these herbal medicines, after extracting the active and pure chemical compounds. Pharmacokinetics and physicochemical properties of the active ingredients was explored. It lead to the better understanding of efficacy and safety profile of these drugs and first choice for treatment of various diseases. At the same time, the herbal medicines were considered as secondarily important. After approximately two centuries, the use of herbal medicines have seen a revival globally both in developing as well as developed countries. In the past few years, the practice of using herbal medicines as an alternative and complementary health medicine has gained more importance. Herbal medicines are common for treatment of various ailments including cancer, digestive disorders, pain related disorders, neuropathic ailments and cardiac arrhythmias etc. Even it has been used by pregnant females and mostly perceived as safe. Its use has gained more attraction due to its ‘natural’ approach and lesser side effects. Their use if often overlooked but physicians should pay attention to these medicines. There is lack of familiarity, standardization of the drug components, unproven therapeutic effects in various diseases, unexplored toxicology, pharmacokinetics, drug-drug interactions, and compatibility in patients with varying medical, genetic and demographic history. There are serious concerns regarding the safety, efficacy and quality of herbal products and nutraceuticals. Accidental contamination and deliberate adulteration are assumed to be the main cause of the side effects. Much of the herbal medical knowledge is scattered in different regions of the world and mostly available at family, community and local level and mostly in any native languages. There is need of coherent sources, knowledge, and exploration of these medicines across the world. The herbal medicine has varying diversity in different geological regions and they should be investigated. There should be a regional or national body to control and approve the herbal medicines. Proper documentations on these medicines and food supplements should also be done.

Thermodynamic Stability, Defect Formation Energetics and Electronic Structure of 4D and 5D Perovskites from First-Principles Calculations

In the present study we explore 4d and 5d perovskite oxides of alkaline-earth metals which find applications in both electronic and renewable energy devices. We investigate the atomic structure, electronic properties and defect formation energies of intrinsic vacancies as well as oxygen vacancy clustering in AZrO3 and AHfO3 (A = Ca, Sr and Ba) compounds. For this purpose all-electron Full-potential linear augmented plane-wave plus local-orbitals method within the framework of density functional theory has been employed. A detailed investigation of the electronic properties of aforementioned compounds is carried out by means of electronic band structures, density of states, charge densities and effective Bader Charges. The chemical stability diagrams of these compounds are also obtained from the total energy calculations which are used for determining the tolerance of the AZrO3 and AHfO3 compounds towards intrinsic vacancy defects under different growth conditions. Moreover, various cases of oxygen vacancy clustering are considered for predicting stable configuration of ordered oxygen vacancies and n-type conductivity in oxygen deficient AZrO3 and AHfO3 perovskite oxides. It is found that pristine AZrO3 and AHfO3 perovskite oxides are large band gap materials. We show that A site metal-atom vacancy is more likely 18 to be achieved during the synthesis of these materials and can be used for tuning p-type nature. On the other hand, the large band gap of all AZrO3 and AHfO3 perovskite oxides can be considerably reduced by introducing isolated oxygen vacancies in these materials. A systematic analysis of ordered oxygen vacancies in different layers of these materials allows us to predict that n-type conduction in AZrO3 and AHfO3 can be realized when oxygen vacancies cluster in the ZrO2 and HfO2 layers of these compounds, respectively. Our results provides useful information concerning the utilization of these materials in electronic, optical and energy devices.