4-Phenyl­semicarbazide

The title compound, C7H9N3O, crystallizes with two independent mol­ecules per asymmetric unit. The structure is stabilized by four distinct inter­molecular N—H⋯O hydrogen bonds. Four intra­molecular inter­actions of the N—H⋯N and C—H⋯O types are also observed

2-Methoxy­benzohydrazide

The title compound, C8H10N2O2, crystallizes as two independent mol­ecules linked by N—H⋯N and N—H⋯O hydrogen bonds into a linear chain running along the a axis of the monoclinic unit cell. The intra- and inter­molecular hydrogen bonds are described as a two-ring R 2 2(10) motif. The six-membered R 1 1(6) rings formed by the intra­molecular inter­actions are almost planar (r.m.s. deviations 0.06 and 0.08 Å). In one mol­ecule, the aromatic and hydrogen-bonded rings are oriented at 4.8 (2)°, whereas in the other mol­ecule these rings are oriented at 6.1 (4)°

4-Iodo­benzohydrazide

In the structure of the title compound, C7H7IN2O, the hydrazide group is inclined at 13.3 (3)° with respect to the benzene ring. The structure is stabilized by inter­molecular N—H⋯N and N—H⋯O hydrogen bonds involving the hydrazide group, resulting in six- and ten-membered rings with R 2 2(6) and R 2 2(10) graph-set notations, respectively

4-Hydroxy­benzohydrazide

In the title compound, C7H8N2O2, the mean planes of the benzene ring and the planar hydrazide group are inclined at 25.75 (6)° with respect to each other. The structure is stabilized by inter­molecular N—H⋯O and O—H⋯N hydrogen bonds

Diagnosed hematological malignancies in Bangladesh - a retrospective analysis of over 5000 cases from 10 specialized hospitals

Background The global burden from cancer is rising, especially as low-income countries like Bangladesh observe rapid aging. So far, there are no comprehensive descriptions reporting diagnosed cancer group that include hematological malignancies in Bangladesh. Methods This was a multi-center hospital-based retrospective descriptive study of over 5000 confirmed hematological cancer cases in between January 2008 to December 2012. Morphological typing was carried out using the “French American British” classification system. Results A total of 5013 patients aged between 2 to 90 years had been diagnosed with malignant hematological disorders. A 69.2% were males (n = 3468) and 30.8% females (n = 1545), with a male to female ratio of 2.2:1. The overall median age at diagnosis was 42 years. Acute myeloid leukemia was most frequent (28.3%) with a median age of 35 years, followed by chronic myeloid leukemia with 18.2% (median age 40 years), non-Hodgkin lymphoma (16.9%; median age 48 years), acute lymphoblastic leukemia (14.1%; median age 27 years), multiple myeloma (10.5%; median age 55 years), myelodysplastic syndromes (4.5%; median age 57 years) and Hodgkin’s lymphoma (3.9%; median age 36 years). The least common was chronic lymphocytic leukemia (3.7%; median age 60 years). Below the age of 20 years, acute lymphoblastic leukemia was predominant (37.3%), followed by acute myeloid leukemia (34%). Chronic lymphocytic leukemia and multiple myeloma had mostly occurred among older patients, aged 50-over. Conclusions For the first time, our study presents the pattern and distribution of diagnosed hematological cancers in Bangladesh. It shows differences in population distributions as compared to other settings with possibly a lower presence of non-Hodgkin lymphoma. There might be under-reporting of affected women. Further studies are necessary on the epidemiology, genetics and potential environmental risk factors within this rapidly aging country

Islanding detection of distributed generation using electrical variables in space vector domain

This paper presents a new approach for islanding detection in distribution systems incorporating synchronous generator (SG) based distributed generations (DGs). The proposed method firstly utilizes the dynamic equations of three electrical variables under islanding situations; the variables are: change-of-frequency, rate-of-change-of-frequency (ROCOF), and rotor angle deviation. Secondly, transformation of these variables is conducted in the space vector (SV) domain which gives rise to three parameters, namely, semi-major axis, semi-minor axis, and inclination angle. Lastly, exploiting these parameters, a decision boundary is established to classify grid events resulting the formation of an island or not. The proposed method is comprehensively investigated under different operating conditions, which include excess/deficit of reactive/active power imbalance scenarios in the formed island containing different load-types (constant impedance, constant power and constant current) with varying quality factor. A large variety of islanding and non-islanding events are generated using a practical distribution network simulated in real-time on OPAL-RT digital simulation platform under the aforementioned operating conditions. A detailed evaluation of the proposed approach is conducted and it demonstrates the effectiveness of the method

Assessing the performance of ROCOF relay for anti-islanding protection of distributed generation under subcritical region of power imbalance

In practice, the load-curve and distributed generation (DG) penetration level determines the power imbalance level that a network can experience if islanding occurs. Therefore, with the prior knowledge of load-curve and DG penetration level, the operating point or setpoint of Rate-of-change-of-frequency (ROCOF) relays can be adjusted so as to make them suitable for a real network. To this end, this paper firstly investigates the subcritical power imbalance region of ROCOF relays through analytical formulation; then, simulation study is conducted under different load-types and at the existence of deficit/excess of active and/or reactive power imbalance scenarios in order to establish the maximum boundary limit of ROCOF under all scenarios. Secondly, employing reliability (assessed by Detection Rate and False Alarm Rate) and response time as key performance indicators, ROCOF's performance is evaluated using numerous islanding and nonislanding events simulated from a test network of Australia. Lastly, ROCOF's performance is assessed using the ROC (Receiver Operating Characteristics) curve along with relay setpoint; the assessment considers the number of islanding events associated with the time-wise percentage of power imbalance level (deficit/excess) calculated from the different DG penetration level and daily load-curve. All these test results demonstrate a clear guideline to select ROCOF's setpoint

Analytical expressions for characterising voltage dips and phase-angle jumps in electricity networks

Voltage dips/sags are one of the major concerns for electricity consumers as well as utility service providers. Therefore, the characterisation of voltage dips/sags is required. This study presents a set of mathematical expressions for characterising different types of voltage dips/sags and their associated phase-angle jumps, which are typically found due to faults and/or disturbances in electricity networks. The expressions are derived analytically from the model of the power network containing generators, transmission and/or distribution lines, transformers etc. Four types of voltage dips, namely, A, B, E, and G, which are associated with four major types of faults including balanced three-phase faults, single line-to-ground, double line-to-ground, and line-to-line faults, are considered to derive the analytical expressions. Dynamic simulation results, using a test distribution system, approve the validity as well as the accuracy of the developed expressions. The influence of fault-types and fault-locations is investigated from the mathematical expressions; further, validation is conducted through a simulation study. The analytical expressions, presented in this study, are a valuable tool in the planning stage since the expressions can be employed to characterise during-fault voltage dips at different buses in electricity network without conducting a large number of repeated dynamic simulations