My Science School

Nettie Stevens was an American geneticist who discovered that sex is determined by chromosome.

Nettie Maria Stevens was born on July 7, 1861, in Cavendish, Vermont. The family moved to Westford, Massachusetts, after her mother's death. In 1896, she joined the then newly established Stanford University earning her under graduation and post graduation degrees there. She received a Ph.D. in cytology (the study of structure and function of cells) from Bryn Mawr College in 1903. Her Ph.D advisor was the geneticist Thomas Hunt Morgan.

In 1904, Nettie was offered a research assistantship position at Carnegie to investigate the topic of heredity and sex determination. Thanks to Gregor Mendel, by 1900, rules of heredity were known to the scientific community. It was well established by then that parental traits pass to offspring and that the offspring inherits an equal number of chromosomes from each of its parents. But scientists did not know what determined the sex of the offspring.

By studying the cell division in the male common mealworm, Nettie identified a large chromosome and a small chromosome - we now call these X and Y. She concluded that a particular combination of the chromosomes X and Y

was responsible for the determination of the sex of an individual an individual that inherits XX will be female and XY will be male this was evidence that a physical characteristic-in this case the sex of an individual - is linked to differences in chromosomes.

Edmund Beecher Wilson of Columbia University Americas first cell biologist independently made the same discovery as Nettie, later in 1908. Bat Thomas Hint Morgan has been credited with the discovery of sex chromosomes because of his related work on white mutant gene of fruit flies and was even awarded a Nobel Prize in 1933 for the same. Nettie was neither recognized immediately after her discovery, nor invited to speak on theories on sex determination while Morgan and Wilson were. Experts attribute this to gender discrimination Nettie remained an associate in experimental morphology from 1905 until her death in 1912 date to cancer. Nettie Stevens discovered two new species of single-celled organisms: Lionophora macfarlandi and Boveria subcylindrica. She also documented their life cycles.

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Max Planck received his Nobel Prize one year later, in 1919. During the selection process in 1918, the Nobel Committee for Physics decided that none of the year's nominations met the criteria as outlined in the will of Alfred Nobel. According to the Nobel Foundation's statutes, the Nobel Prize can in such a case be reserved until the following year, and this statute was then applied. Max Planck therefore received his Nobel Prize for 1918 one year later, in 1919.

Planck’s earliest work was on the subject of thermodynamics, an interest he acquired from his studies under Kirchhoff, whom he greatly admired, and very considerably from reading R. Clausius’ publications. He published papers on entropy, on thermoelectric ity and on the theory of dilute solutions.

At the same time also the problems of radiation processes engaged his attention and he showed that these were to be considered as electromagnetic in nature. From these studies he was led to the problem of the distribution of energy in the spectrum of full radiation. Experimental observations on the wavelength distribution of the energy emitted by a black body as a function of temperature were at variance with the predictions of classical physics. Planck was able to deduce the relationship between the ener gy and the frequency of radiation. In a paper published in 1900, he announced his derivation of the relationship: this was based on the revolutionary idea that the energy emitted by a resonator could only take on discrete values or quanta. The energy for a resonator of frequency v is hv where h is a universal constant, now called Planck’s constant.

This was not only Planck’s most important work but also marked a turning point in the history of physics. The importance of the discovery, with its far-reaching effect on classical physics, was not appreciated at first. However the evidence for its validi ty gradually became overwhelming as its application accounted for many discrepancies between observed phenomena and classical theory. Among these applications and developments may be mentioned Einstein’s explanation of the photoelectric effect.

Credit : Nobel Prize

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Planck’s constant, (symbol h), fundamental physical constant characteristic of the mathematical formulations of quantum mechanics, which describes the behaviour of particles and waves on the atomic scale, including the particle aspect of light. 

The significance of Planck’s constant in this context is that radiation, such as light, is emitted, transmitted, and absorbed in discrete energy packets, or quanta, determined by the frequency of the radiation and the value of Planck’s constant. 

The dimension of Planck’s constant is the product of energy multiplied by time, a quantity called action. Planck’s constant is often defined, therefore, as the elementary quantum of action. 

Planck's constant was formulated as part of Max Planck's successful effort to produce a mathematical expression that accurately predicted the observed spectral distribution of thermal radiation from a closed furnace (black-body radiation). This mathematical expression is now known as Planck's law.

In the last years of the 19th century, Max Planck was investigating the problem of black-body radiation first posed by Kirchhoff some 40 years earlier. Every physical body spontaneously and continuously emits electromagnetic radiation. There was no expression or explanation for the overall shape of the observed emission spectrum.

Credit : Britannica

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Max Planck was a German theoretical physicist who won the Nobel Prize for Physics in 1918 for his work on the quantum theory, which revolutionised human understanding of atomic and subatomic processes.

Max Karl Ernst Ludwig Planck was born in Kiel, Germany, to Julius Wilhelm and Emma Planck. Planck studied physics at the Universities of Munich and Berlin, and received his doctorate of philosophy at Munich in 1879 after completing his paper detailing his research and theory of thermodynamics, an interest he acquired from his studies under physicist Gustav Robert Kirchhoff, whom he greatly admired. His dissertation in the second law of thermodynamics laid the ground for his future researches, which eventually led him to discover the quantum of action, now known as Planck's constant h.

In 1885, the University of Kiel appointed Planck as associate professor of theoretical physics. In 1892, he became a professor at the University of Berlin.

In 1894, he turned his attention to the problem of black-body radiation. In 1859-60 Kirchhoff had defined a black body as an emitter and absorber of radiation. But there was a mismatch between the wavelengths radiated by black body and the wavelengths predicted by classical theories of thermodynamics. When a black body is heated, electromagnetic radiation is emitted with a spectrum corresponding to the temperature of the body, and not to its composition. This led Planck to propose the concept of quanta. In 1900, he suggested that light and other electromagnetic waves were emitted in discrete units of energy, which he called "quanta" (multiples of a certain constant. which now bears the name "Planck's constant). The discovery of Planck's constant enabled him to define a new universal set of physical units such as the Planck length and the Planck mass. Planck's concept of energy quanta was accepted only years later but is considered one of the scientific breakthroughs that most contributed to modern physics. During World War Two, his home was completely destroyed by bombings in 1944 and he lost all of his papers. Did you know Max Planck was talented musically? He composed classical music and played the cello and the piano.

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After graduating from Seattle High School in 1910, Ball went on to study at the University of Washington, achieving two bachelor’s degrees in pharmaceutical chemistry and the science of pharmacy by 1914. That same year, she co-authored a paper on benzoylations in ether solution that was published in the prestigious Journal of the American Chemical Society, a rare feat for a Black woman at this time.

In 1915, Ball became the first woman and the first African-American person to receive a master’s degree from the College of Hawaii (now known as the University of Hawai’i) and to teach chemistry there. She became the head of the chemistry department later that year. As a postgraduate, she researched the chemical makeup and active ingredients of kava root (Piper methysticum).

It was this work that led Harry T. Hollmann, an assistant surgeon at Kalihi Hospital in Honolulu, to ask Ball to join his team researching treatments for leprosy, a chronic bacterial infection that can lead to skin lesions and nerve damage.

At the time, leprosy (also known as Hansen’s disease) was a highly stigmatised condition. In Hawai’i, people with severe cases were exiled to a facility called Kalaupapa on the island of Molokai, where they were forced to live in isolation until they died. The US novelist Jack London described Kalaupapa as “the pit of hell, the most cursed place on earth”.

The only treatment for the disease at the time was an oil taken from the seeds of the chaulmoogra tree (Hydnocarpus wightianus), a plant native to eastern regions of Asia that had been used in traditional medicine since the 1300s. The application of chaulmoogra oil was extremely difficult – its acrid taste often induced vomiting, while it was hard to use topically because it was too sticky. Injecting the oil was extremely painful and it would often clump under the skin to form blisters.

Credit : New Scientist

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Alice Ball was an African American chemist who developed the first successful treatment for those suffering from Hansen’s disease (leprosy). Ball was also the very first African American and the first woman to graduate with a M.S. degree in chemistry from the College of Hawaii (now known as the University of Hawaii). Tragically, Ball died at the young age of 24. During her brief lifetime, she did not get to see the full impact of her discovery. It was not until years after her death that Ball got the proper credit she deserved.

After earning undergraduate degrees in pharmaceutical chemistry (1912) and pharmacy (1914) from the University of Washington, Alice Ball transferred to the College of Hawaii (now known as the University of Hawaii) and became the very first African American and the very first woman to graduate with a M.S. degree in chemistry in 1915. She was offered a teaching and research position there and became the institution’s very first woman chemistry instructor. She was only 23 years old.

As a laboratory researcher, Ball worked extensively to develop a successful treatment for those suffering from Hansen’s disease (leprosy). Her research led her to create the first injectable leprosy treatment using oil from the chaulmoogra tree, which up until then, was only a moderately successful topical agent that was used in Chinese and Indian medicine. Ball successfully isolated the oil into fatty acid components of different molecular weights allowing her to manipulate the oil into a water soluble injectable form. Ball’s scientific rigor resulted in a highly successful method to alleviate leprosy symptoms, later known as the “Ball Method,” that was used on thousands of infected individuals for over thirty years until sulfone drugs were introduced.

Credit : Biography.com

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Alice Augusta Ball was an African American chemist who developed an injectable oil extract, the first successful treatment for leprosy. It was used until the 1940s. However, she did not get credit for her discovery for nearly 90 years. Some attribute this to gender and racial discrimination.

Ball was born in 1892, in Washington, to James Presley, a newspaper editor, and Laura Louise, a photographer. After graduating from Seattle High School in 1910, Ball earned her bachelor's degree in pharmaceutical chemistry from the University of Washington, and her master's degree from the College of Hawaii (now known as the University of Hawaii), in 1915. Alice Ball was the first woman and first African American to receive a master's degree from the University of Hawaii and the first woman chemistry professor at the university.

In her postgraduate research career at the University of Hawaii, Ball investigated the chemical makeup and active principle of Piper methysticum (kava - a herbal plant grown in the Pacific islands) for her master's thesis.

Impressed with her work, Dr. Harry T. Hollmann, a doctor at the Kalihi Hospital in Hawaii that treated patients with leprosy, reached out to Ball to isolate the active chemical compounds in chaulmoogra oil. Chaulmoogra oil had previously been used in the treatment of leprosy with mixed results and severe side effects. An ideal treatment, Dr. Hollmann thought, would be a solution made from the active components of the oil that could be injected without side effects.

In less than a year, Ball developed a technique that would allow the oil from chaulmoogra tree seeds to become injectable and absorbable by the body. She was just 23 years then. Her newly developed technique involved isolating ethyl ester compounds from the fatty acids of the chaulmoogra oil. This isolation technique, later known as the Ball Method, was the only pain-free treatment for leprosy available for over thirty years until sulfone drugs were introduced. Unfortunately, Ball died in 1916, at the young age of 24, before publishing her findings. The president of the College of Hawaii, Dr. Arthur Dean, continued and published Ball's research without giving her credit for the discovery. Dean even called the treatment. "Dean Method." Ball's name might have been completely forgotten but thanks to Dr. Hollmann, who in a 1922 medical journal credited Ball for creating the chaulmoogra solution and referred to it as the "Ball Method."

Even so, Ball remained largely forgotten until 2000, when the University of Hawaii placed a bronze plaque in front of a chaulmoogra tree on campus to honour Ball's discovery. In 2007, the University of Hawaii posthumously awarded her with the Regents Medal of Distinction.

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Jane Cooke Wright (1919 – 2013) was an American medical researcher who did pioneer work in chemotherapy. Her contributions to oncology revolutionised cancer treatment across the world.

Louis Tompkins Wright was a well-known surgeon and medical researcher and was the first African-American to be a staff physician at a New York City hospital. Both Jane Cooke Wright and her younger sister, Barbara, followed in the family tradition and became doctors, overcoming both gender and racial bias.

After medical school, Wright worked in Bellevue Hospital (1945–46) and Harlem Hospital (1947–48). Her interest in chemotherapy drugs was sparked when she joined her father in research at the Harlem Cancer Research Center in 1949. Jane Wright studied the reactions of different drugs and chemotherapy techniques on tumours. At the time, chemotherapy was still a nascent area. There was scepticism about chemotherapy and it was not widely practised. Jane Wright’s research transformed that.

Jane Wright pioneered the use of the drug methotrexate to treat breast cancer (in 1951) and skin cancer (1960). She is also credited with developing the technique of using human tissue culture to test the effects of potential drugs on cancer cells. Adjusting treatment according to the individual was an idea forming the basis of much of Wright’s research. Wright also developed non-surgical methods to deliver drugs to tumours, even those deep within the body, using catheter systems.

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Jane Cooke Wright was an American medical researcher who did pioneer work in chemotherapy. Her contributions to oncology revolutionised cancer treatment across the world.

Jane Wright was born in New York City in 1919 into a family of physicians. Her father, Louis Tompkins Wright, and her paternal grandfather, Ceah Ketcham Wright, were doctors. Louis Tompkins Wright was a well-known surgeon and medical researcher and was the first African American to be a staff physician at a New York City hospital. Both Jane Cooke Wright and her younger sister, Barbara, followed in the family tradition and became doctors, overcoming both gender and racial bias.

After medical school, Wright worked in Bellevue Hospital (1945-46) and Harlem Hospital (1947-48). Her interest in chemotherapy drugs was sparked when she joined her father in research at the Harlem Cancer Research Center in 1949. Jane Wright studied the reactions of different drugs and chemotherapy techniques on tumours. At the time, chemotherapy was still a nascent area. There was scepticism about chemotherapy and it was not widely practised. Jane Wright's research transformed that.

Jane Wright pioneered the use of the drug methotrexate to treat breast cancer (in 1951) and skin cancer (1960). She is also credited with developing the technique of using human tissue culture to test the effects of potential drugs on cancer cells. Adjusting treatment according to the individual was an idea forming the basis of much of Wright's research. Wright also developed non-surgical methods to deliver drugs to tumours, even those deep within the body, using catheter systems.

Following Dr. Louis Wright's death in 1952, Jane Wright was appointed head of the Harlem Cancer Research Foundation. In 1955, she became the director of cancer chemotherapy research at New York University Medical Center and its affiliated Bellevue and University hospitals.

In 1971, Jane Wright became the first woman president of the New York Cancer Society. She retired from the New York Medical College and active cancer research in 1987. During her life time, she had published 135 scientific papers and written nine books.

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A crescograph is a device for measuring the growth in plants. It was invented in the early 20th century by Sir Jagadish Chandra Bose.

The Bose crescograph uses a series of clockwork gears and a smoked glass plate to record the movement of the tip of a plant (or its roots). It was able to record at magnifications of up to 10,000 times through the use of two different levers. One lever records at 100 times magnification while the other lever takes that image and records at another 100 times magnification. Marks are made on the plate at intervals of a few seconds, demonstrating how the rate of growth varies under varying stimuli. Bose experimented with temperature, chemicals, gases, and electricity.

The electronic crescograph plant movement detector is capable of measurements as small as 1/1,000,000 of an inch. However, its normal operating range is from 1/1000 to 1/10,000 of an inch. The component which actually measures the movement is a differential transformer along with a movable core hinged between two points. A micrometer is used to adjust and calibrate the system. It can record plant growth, magnifying a small movement as much as 10,000,000 times.

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Jagadish Chandra Bose was a polymath whose two major works came from two distinct fields of science electromagnetism and plant physiology. He was considered the first modem and experimental scientist of India.

J.C. Bose was born in 1858 in Bengal Presidency (which is now a place in Bangladesh). Bose graduated from St. Xavier's College. Calcutta, and went on to do Natural Science from Cambridge University. He conducted researches with the English physical scientist Lord Rayleigh at Cambridge and returned to India in 1885. He found himself a join at the Presidency College, Calcutta, on a temporary basis, where he was subjected to racial discrimination. Later he was made permanent and was given a dingy laboratory to conduct his experiments in. Colonial British did not encourage original research by Indians.

Inventions in wireless waves

Working from here, Bose followed up on German physicist Heinrich Hertzs discovery of electromagnetic waves. Bose came up with the Millimetre Waves, the shortest radiowaves of 5mm. In 1895, Bose demonstrated wireless transmission of electromagnetic waves to the public in Calcutta. And the world started taking notice of this modern scientist from India. In 1899, Bose came up with another development the iron-mercury-iron coherer, a primitive form of radio signal detector, and presented it at the Royal Society, London. Years later Marconi transmitted radio waves across the Atlantic using Bose's coherer. Bose also has the distinction of using a semiconductor junction to detect radio waves for the first time.

Plants have feelings too

From electromagnetic waves, Jagdish Chandra Bose's attention turned to plant biology. In 1901, he showed that plants are also sensitive to and temperature. Bose demonstrated how poison could create human-like suffering in plants using an instrument he developed-crescograph. He had a plant dipped up to its stem in a vessel containing a poisonous bromide solution. When the crescograph with the plant was plugged in. people could view how the lighted spot on a screen showed the movements of the plant which beat, vibrated and stopped, corresponding to the plant's suffering and death.

Legacy

Bose founded a research institute - Bose Institute in Calcutta in 1971. The same year, he was knighted by the British government. In 2009, on his 150th birth anniversary, Bose was honoured as one of the Fathers of Radio Science.

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