Showing posts with label zlatest. Show all posts
Showing posts with label zlatest. Show all posts

Ski Patrol Trail Condition Questions

 

Figure 1: Ski Slope, Full View Uphill

Figure 2: Marking, Skier's Left

Figure 3: Marking, Skier's Right

The ski slope is marked as shown in Figures 1-3. 

  1. When assessing the risk of hypothermia in the depicted environment, which factor is most critical? A. Wind chill
    B. Proximity to a heat source
    C. Time of day
    D. Visibility
    E. Wildlife activity

  2. Considering avalanche safety, which of the following should be regularly checked in such an environment?
    A. Snowpack stability
    B. Forecasted temperatures
    C. Pathway obstructions
    D. Wildlife migration patterns
    E. Trail markers

  3. What is the primary concern for ski patrol when the snow on the trees is as heavy as shown?
    A. Ensuring visibility of trail markers
    B. Monitoring for signs of tree falls
    C. Clearing pathways of snow
    D. Checking for frozen lakes
    E. Patrolling for lost skiers

  4. Given the conditions shown, what is the most likely cause of a trail closure?
    A. Ice formation on the path
    B. Low visibility due to fog
    C. Snow overload on branches
    D. Inaccessibility due to heavy snowfall
    E. Daylight limitations

  5. Which of these is an essential communication tool for teams in such remote and snowy conditions? A. Mobile phone
    B. Two-way radio
    C. Public address system
    D. Satellite phone
    E. Megaphone

  6. When marking hazards on the trail, what characteristic of the markers is most crucial?
    A. Height above the snow
    B. Color contrast with the environment
    C. Frequency along the trail
    D. Reflectiveness
    E. Size of the marker

  7. What environmental change should be most closely monitored to prevent hypothermia and frostbite in patrollers?
    A. Snow density
    B. Ambient temperature
    C. Humidity levels
    D. Wind speed
    E. Barometric pressure

  8. For patrollers conducting a search operation, what is the most significant terrain challenge indicated by the images?
    A. Steep inclines
    B. Open crevasses
    C. Dense forest areas
    D. Snow-covered paths
    E. Icy patches

  9. During end-of-day checks, what is a key environmental sign that patrollers should report?
    A. Decreasing temperatures
    B. Changes in snow texture
    C. Animal tracks
    D. Partially covered trail markers
    E. Melting snow around water bodies

Answers:

  1. A
  2. A
  3. B
  4. D
  5. B
  6. B
  7. B
  8. C
  9. D


Is BaSO4 soluble or insoluble?

Answer: BaSO4 would typically be considered insoluble due to the presence of a sulfate ion. This usually precludes an ion from disassociating easily in an aqueous solution; this being water. 

The idea of BaSO4 being considered insoluble is further borne out in the Ksp values. While these cannot be directly related to molar solubility, they provide a strong hint that Barium sulfate is more stringent than other comparable molecules. For example Ba(OH)2's ksp is approximately seven orders of magnitude less which means that it is much more likely to ionize. You can tell that the molar solubility of barium hydroxide is orders of magnitude greater without performing the necessary calculations. As a reminder a compound is considered insoluble if less than 1% of the compound ionizes. 

Barium Products Ksp Values
ksp values of some common Barium products (source)

What is the molar solubility of BaSO4?

The calculation is based on the chemical equation for the disassociation of BaSO4 and the formula for ksp (equilibrium constants only include aqueous and gaseous species). 

BaSO₄(s) ⇌ Ba²⁺(aq) + SO₄²⁻(aq)

K_sp = [Ba²⁺][SO₄²⁻]

Since when we ionize we create the two ions in equal molar quantity we can state the following

[Ba²⁺] = [SO₄²⁻] = x

$1.1*10^-10 = x^2$

x = $1.05*10^-5$ M

This concentration indicates that less than 1% of the solution is composed of ionized species. 

How does BaSO4 theoretically ionize? 

As the equation (BaSO4 (s) => Ba(2+)(aq) + SO4(2-)(aq)) indicates, barium sulfate would disassociate and produce the barium and sulfate ion. In the real world; however, the low molar solubility indicates that very little barium sulfate actually ionizes. 

What experimental techniques can be utilized in order to verify the solubility of BaSO4?

Experimental observations play a crucial role in confirming the insolubility of barium sulfate. Several methods and techniques are employed to assess the solubility of a compound, and in the case of barium sulfate, the following experimental observations contribute to our understanding of its insolubility:

  1. Precipitation Reaction: One common method to demonstrate the limited solubility of barium sulfate is through a precipitation reaction. When a soluble barium salt (e.g., barium chloride, BaCl₂) is added to a solution containing a soluble sulfate salt (e.g., sodium sulfate, Na₂SO₄), a white precipitate of barium sulfate forms. The appearance of the precipitate indicates that the compound is not fully dissolving in the solution, supporting its insoluble nature.

BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)

  1. Gravimetric Analysis: Gravimetric analysis is a quantitative method used to determine the concentration of a particular species in a solution by measuring its mass. In the case of barium sulfate, after precipitating the compound as mentioned above, the collected precipitate is filtered, washed, and dried to remove any remaining soluble impurities. The mass of the resulting dried barium sulfate is then measured, and from the stoichiometry of the reaction, the concentration of dissolved barium ions can be calculated. The extremely small mass of barium sulfate obtained in these experiments is indicative of its low solubility.

  2. Solubility Curves: A solubility curve represents the relationship between temperature and the solubility of a compound. For barium sulfate, a solubility curve can be constructed by determining the concentration of dissolved barium ions at various temperatures. The resulting curve shows that the solubility of barium sulfate is virtually constant over a wide temperature range, consistent with its insoluble nature.

  3. Saturation Point: By adding barium sulfate to water and continuously stirring the mixture, a saturation point is eventually reached where no more solid will dissolve, and any additional barium sulfate added will not disappear into the solution. This point is critical as it shows the maximum concentration of dissolved barium ions that can be achieved, providing further evidence of the compound's limited solubility.

Together, these experimental observations provide strong evidence for the insolubility of barium sulfate in water and support the theoretical understanding derived from the thermodynamics and solubility product constant (K_sp) considerations. The combination of theoretical principles and experimental data reinforces our confidence in the knowledge that barium sulfate is indeed highly insoluble in aqueous solutions.

What are the other properties of BaSO4?

Barium sulfate (BaSO₄) possesses several noteworthy properties, some of which are outlined below:

  1. Physical State: Barium sulfate is a white, crystalline solid at room temperature. It occurs naturally as the mineral "barite" and is commonly synthesized for various applications.

  2. Density: Barium sulfate has a relatively high density, typically around 4.5 grams per cubic centimeter (g/cm³). This density makes it useful for certain applications, such as in radiology as a contrast agent.

  3. Insolubility: As previously discussed, barium sulfate is highly insoluble in water and most common solvents. This property contributes to its use in medical imaging procedures (e.g., barium sulfate suspensions for X-ray examinations of the gastrointestinal tract) and as a filler in various materials.

  4. Chemical Inertness: Barium sulfate is chemically inert, meaning it does not readily react with other substances under normal conditions. This inertness is advantageous in applications where chemical stability is essential, such as in paints, coatings, and plastics.

  5. Non-Toxicity: Barium sulfate is considered non-toxic, which further supports its use in medical applications. When consumed in small quantities (e.g., in medical tests), it passes through the body without being absorbed or causing harm.

  6. Refractive Index: Barium sulfate has a relatively high refractive index, making it useful as a filler in products like paint and plastics to enhance opacity and brightness.

  7. Thermal Stability: Barium sulfate exhibits good thermal stability, retaining its physical and chemical properties at elevated temperatures. This characteristic makes it suitable for applications in industries where high temperatures are involved.

  8. Electrical Insulator: Due to its non-conductive nature, barium sulfate serves as an excellent electrical insulator. This property is valuable in applications where electrical isolation is necessary, such as in electronic devices and insulating materials.

  9. X-ray Absorption: Barium sulfate has high X-ray absorption properties, which is why it is used as a contrast agent in medical imaging procedures like barium X-rays. It allows for clear visualization of the gastrointestinal tract and certain anatomical structures.

  10. Photographic Uses: Barium sulfate was historically used in black-and-white photography as a white pigment in photographic paper and certain emulsions.

Overall, the unique combination of properties exhibited by barium sulfate makes it valuable in various industrial, medical, and commercial applications. Its insolubility, chemical inertness, and X-ray absorption properties, in particular, make it a versatile and sought-after material in different fields.

Is H2S Polar or Nonpolar?

Answer: H2S is a polar molecule due to the presence of lone pair electrons at the top of the molecule causing a region of partial negative charge due to electron-electron repulsion. 

H2S has a very similar structure as H2O (see the lewis dot structure for H2O and the polar/nonpolar explanation at the linked addresses). However, due to the larger size of the sulfur atom compared to oxygen, the bond angle (i.e. the smaller angle between the two hydrogen atoms) is only 92˚ compared to 107.5˚ for H2O. Sulfur contains many more electrons which ultimately due to electron-electron repulsion require a lot more space. Nevertheless the decreased electronegativity of sulfur when compared to hydrogen (2.58 vs. 2.20, respectively) means that the molecule is much less polar overall when compared to H2O. This means that it has a much lower melting and boiling point at -82˚C and -60˚C, respectively. Like SO2 the presence of sulfur means that this molecule has a pungent odor in gaseous form although it is colorless. 

H2S Ball and Stick Diagram
H2S Ball and Stick Diagram. Created with MolView.

How is H2S utilized in the real world?

Hydrogen sulfide appears in many different ways within the natural world. For starters it is an important constituent of the sulfur cycle. Bacteria oftentimes convert the sulfur from organic elements to inorganic molecules such as H2S. The main use of hydrogen sulfide is as a storage compound which can be converted to pure sulfur during reactions to form all kinds of sulfur-containing compounds. Hydrogen sulfide may have also caused a mass extinction due to its buildup within the atmosphere. Based on this fact it is not difficult to imagine the toxicity of hydrogen sulfide towards life forms such as human beings. It negatively impacts proper nervous system functioning primarily although it will affect other body systems as well. Nevertheless there are certain organisms adapted to live in high-H2S conditions due to those environments existing in deep underwater volcanic sea vents.  

The Lewis Dot Structure for Acetic Acid (CH3COOH)

Lewis Dot Structure for Acetic Acid
Created by MakeTheBrainHappy.

Above is the Lewis Dot Structure for Acetic Acid (CH3COOH). You could alternatively also draw the structure by including two dots for every bond. As you can see every single element has a filled valence shell with the two oxygen's each containing two lone pairs of electrons, the only instance of this phenomena within the Lewis Structure. In a sense this is a modified structure of methane (CH4) with the replacement of one hydrogen with the replacement of a carboxylic group (-COOH). As we will see the properties we observe within the Lewis structure have a significant impact on the properties of acetic acid.

The Greek Philosopher Theophrastus. Source

What is the history of acetic acid?

Due to the importance of different alcohols such as beer and wine in early civilizations, vinegar became one of the earliest chemical substances that was familiar to ancient peoples. Vinegar is formed by natural fermentation processes and contains approximately 5% acetic acid. One of the earliest mentions of acetic acid was by the Greek Philosopher Theophrastus who explained how to form different pigments, including those for white and green colors, with vinegar as an important constituent ingredient. 

Is Acetic Acid (CH3COOH) Polar or Nonpolar?

Acetic Acid (CH3COOH) is a polar molecule due to the presence of the functional group COOH, a carboxylic acid. It is also an acid in solution, releasing a small number of protons into solution which form H3O+. Due to its polar qualities it is found as a liquid at standard temperature and pressure in relation to its rather light molar mass. It has a melting point is between 16˚C to 17˚C while the boiling point is between 118˚C and 119˚C. These are again elevated due to the polarity of acetic acid. 

How is Acetic Acid (CH3COOH) utilized in the real world?

Acetic acid is useful due to its properties as a polar solvent and building block for other molecules, containing both a methyl (CH3) and COOH functional group. Nearly one third of produced acetic acid is utilized in order to produce "Elmer's glue" material. Inks, paints and coatings are also created via a reaction involving acetic acid. It is frequently utilized as a polar solvent in lab research settings and thereby has been involved in certain medical practices. As mentioned above acetic acid is also present in vinegar which has a variety of household uses; however, the acetic acid is diluted in water to a greater degree than in a research lab.  






Downloading FASTQ Files Quickly utilizing IBM’s Aspera Connect on a LINUX or MAC Machine

Please note that this guide is based on this BioStars thread and this GitHub repository. 


Procedure:


  1. Download the latest version of Aspera Connect from the IBM “featured client software” section (you may need to install a browser extension as well)


  1. Download the file “ena-fast-download.py” from wwood’s GitHub repository


  1. Open the script in your favorite python editor and scroll down to the bottom. Add the specific file path to the ascp field (addition highlighted below)


aspera_commands = []

    for url in ftp_urls:

        quiet_args = ''

        if args.quiet:

            quiet_args = ' -Q'

        cmd = "/Users/USER/Applications/Aspera\ Connect.app/Contents/Resources/ascp{} -T -l 300m -P33001 {} -i {} era-fasp@fasp.sra.ebi.ac.uk:{} {}".format(

            quiet_args,

            args.ascp_args,

            ssh_key_file,

            url.replace('ftp.sra.ebi.ac.uk',''), output_directory)

        logging.info("Running command: {}".format(cmd))

        subprocess.check_call(cmd,shell=True)


logging.info("All done.") 


  1. Save the file. Move the file to the directory where you want FASTQ files to be deposited into. Run the following command in terminal for each accession number (example highlighted):


./ena-fast-download.py ERR1739691 --ssh_key osx 


Note: Sequential commands can be done through a looped text file call or with the ; operator (ex. ./ena-fast-download.py key1 --ssh_key osx ; /ena-fast-download.py key2 --ssh_key osx)


Note 2: For this method it is recommended that you utilize a bash terminal.

The Lewis Dot Structure for KCl

Lewis Dot Structure for KCl
Created by MakeTheBrainHappy.
Please find above the Lewis Dot Structure for KCl (Potassium Chloride). As per usual you could replace the one bond with two electrons. In the case for KCl the electronegativity difference between potassium and chloride is so strong (.82 vs. 3.16, respectively) that the bond is considered ionic. The electrons aren't really considered "shared"; rather, the valence electrons are nearly completely coopted by the chloride. This property as illustrated by the Lewis Dot Structure gives KCl many of its properties as will be explored in the following paragraphs.

KCl Dissolving in Water.
KCl Dissolving in Water. Source
How does KCl (potassium chloride) act as a solute?

As a result of its ionic character as shown in the Lewis Dot Structure it has a great partial positive and partial negative charge on either end. Therefore it dissolves very well in polar solvents such as water (shown above). Water molecules essentially surround the different individual ions and thereby disassociate the salt into solution. However since you need many water molecules per ion there can be a point where you saturate the solution. This means that no more salt can be disassociated unless you add more of the polar solvent.

KCl Ball and Stick Structure
KCl Molecule. Created with MolView.
Is KCl (potassium chloride) polar or nonpolar?

As you may have guessed from the above paragraph, KCl is a polar molecule due to the great electronegativity difference discussed before. This incredibly large difference means that the compound is a solid at standard pressure and temperature with a melting point of 770˚C and a boiling point of 1420˚C. The act of disassociation as mentioned above is not equivalent to melting the pure compound into a liquid as we are discussing here. These properties are also presupposed in the Lewis Dot Structure for KCl.

KCl Salt
KCl Salt. Source
How is KCl (potassium chloride) utilized in the real world?

There are a wide variety of uses for potassium chloride. There are different fertilizers which are composed of KCl for usage in agriculture. Due to the necessity of potassium in biological systems the salt form shown above is often consumed by those who are potassium-deficient. In regular food it can be utilized as a table salt (NaCl) substitute in order to lower the actual Na+ salt content in someones diet. Lastly it is found in many different niche industrial uses as a "ice" salt or in the creation of potassium metal for example. In conclusion, the different properties that allow for these utilizations are exemplified by the Lewis Dot Structure for KCl.

The Lewis Dot Structure for CS2

CS2 Lewis Dot Structure
CS2 Lewis Structure. Created by MakeTheBrainHappy
This is the Lewis Dot Structure for Carbon Disulfide (CS2). As we've discussed before you could replace each bond with two electrons which would represent well how through the sharing of electrons each atom achieves a full octet. The combination of four electrons for the bonds and four electrons in lone pairs equals eight for sulfur while bonds supply eight electrons for the central carbon atom. This is a common feature for carbon as it is unlikely for this element in particular to have lone pair electrons.

The lewis dot structure for CS2 also predicts many of the properties of the molecule. Due to the presence of large sulfide atoms over for comparison oxygen atoms in CO2 the molecule has a greater capacity for temporary london dispersion forces. As a result there can be more induced dipoles which increases the solubility of CS2. The compound is slightly soluble within water and much more soluble in less polar compounds such as alcohol or even nonpolar compounds like benzene.

CS2 Liquid State
CS2 Liquid State. Source
How is CS2 utilized in the real world?

Due to the stronger induced dipoles CS2 also has a greater melting and boiling point. This means that the compound is a liquid at standard temperature and pressure. This concept is discussed further in our article on the polarity of CS2 which you can learn more about in the next section. There are only a limited number of uses for CS2 due to its pretty toxic properties. One of these uses is as a solvent for other nonpolar compounds. These include many elements like phosphorus and sulfur and also larger compounds like fats, resins and rubber. There also other uses for different chemical reactions involved in metallurgy and rubber production. One of the most popular reactions involving CS2 produces carbon tetrachloride (CCl4).

Is CS2 polar or nonpolar?

If you are interested in learning more about this subject, feel free to read this article on whether CS2 is polar or nonpolar. The article will also discuss some of the ways in which CS2 differs from CO2. In addition it will also go into the underlying reasons behind the determination of CS2s polarity.

Volcanic Eruption
Volcanic eruption. Source
How can CS2 be formed naturally?

CS2 (carbon disulfide) can be formed naturally by volcanic eruptions or in marshes. The way this reaction occurs is actually very compatible with how you can see the molecule within the Lewis Dot Structure. Elemental carbon and sulfide combine at very high temperatures to form CS2. However, it should be noted that there is only a very small amount of the compound formed in this process. 

Biography of J. Isfred Isidore Hofbauer (J. Hofbauer)

J. Isfred Isidore Hofbauer Portrait
undated photo of J. Hofbauer [1]

J. (Jsidro) Isfred Isidore Hofbauer or simply J. Hofbauer (born September 8th, 1871 in Vienna, Austria - March 13th, 1961 in Cincinnati, US) was a Austrian-born American gynecologist who performed extensive studies of obstetric organ systems and pioneered new treatments with regard to childbirth. Furthermore, he doubled as an oncologist formulating early operations to treat breast cancer. [2]

Early Life

Hofbauer was of Scandinavian and Austrian heritage. [3] His parents were Moritz Hofbauer and Jeanette Gewitsch. [4]

John's Hopkins Medical School Women's Clinic - circa 1924
Johns Hopkins Hospital Women's Clinic circa 1924. [5]

University Associations

He studied at medicine at the University of Vienna. He did his residency at the Nothnagel Clinic and the Women's Clinic at the Bettina Pavilion. He studied under Friedrich Shauta and Ernst Wertheim for his postgraduate work. He was the lead doctor in the Women's Clinic at Königsberg University from between 1906 and 1912. In 1909 he became the chair of gynecology and obstetrics at the University of Königsberg. He was invited in 1924 by John Whitridge Williams to join the faculty of Johns Hopkins University, where he served as an Associate Professor. In 1933 he moved to the University of Cincinnati where he continued to be an Associate Professor of Obstetrics and gynecologist at the Jewish and Good Samaritan Hospitals. [2,3,4]

Scientific Career

In 1896, J. Hofbauer proposed a "neuclein" treatment for severe infections about childbirth, providing a positive assessment as to its potential due to positive results in seven patients. [6] He continued to experiment with this treatment, continuing to report positive while others in the field attempted to extend the field to inoculation from disease as well. [7] Hofbauer was known to emphasize the techniques efficiency when delivered via the stomach. [7] At the time the "neuclein" was defined to be the part of blood serum left over after digestion within the stomach. [8] Although it was theorized that special "white blood cells" within the blood with phagocytic properties were responsible for the remedy for bacterial infection, this was only one of a few competing theories. [8] The injection of serum was typically accompanied by a saline solution injection and occasionally damaged the bone marrow of the patients [9]. Studies by other researchers to "inoculate" for specific bacteria with blood serum injections were unsuccessful [7].

J. Hofbauer - Biology of the Human Placenta Cover Page
Translation: Biology of the Human Placenta with a special emphasis on the question of fetal nourishment by Dr. J. Hofbauer

J. Hofbauer published a book in 1905 regarding a morphological study he conducted of the human placenta. [10] He described visible "fat cells" within the developing fetus. [11] There was also a special kind of "vacuolated" cell that he described in great detail within the book.

"Vacuolated" cells within the first Table in Appendix of J. Hofbauer's book.

In his 1925 paper entitled "THE FUNCTION OF THE HOFBAUER CELLS OF THE CHORIONIC VILLUS PARTICULARLY IN RELATION TO ACUTE INFECTION AND SYPHILIS" [12], J. Hofbauer translated his original description of the cells which would later become known as Hofbauer cells:
“These specific cells make their appearance by the end of the fourth week of pregnancy. They are comparatively abundant in the early stages of the placenta and decrease in number later on, as the connective tissue of the villus gradually assumes a more fibrous character. The duration of life of the individual cells is shown by the fact that they vanish after total vacuolization. In the cytoplasm which primarily contains homogenous or delicate granules, minute pellucid spots gradually appear about the periphery of the nucleus; later increase in size, and form a clear area surrounding it. These spaces which are filled with fluid and are separated from one another by thin septa, may fuse together, and thus give rise to larger vacuoles. Similar foam-like structures subsequently occur in the peripheral zone of the cells, as well. Furthermore, an essential part of the cytoplasm is represented by smaller and larger granules. In the beginning, these cells are intimately connected with the stroma cells of the villi and are to be considered as descendants of the original mesenchyme. Marchand holds the same view. Staining fresh placental tissue with neutral red throws the vacuolated cells into the boldest relief, while the surrounding tissue remains unstained. It is the granules and the vacuoles of the cells which take up the dye with avidity. These are the fundamental structural constituents of the cells in question, and they may play a considerable biologic part. As to their physiologic role, we can only say that they probably possess a digestive function,--a view which is supported by the presence of fat in the vacuoles, as well as of neutral red. The phagocytic power is further supported by the fact that at the stage of development, when the nucleated red blood cells lose their nuclei, I could demonstrate the disintegration of their nuclei within the fetal capillaries of the chorionic villi, and that the fragments of the nuclei were engulfed by the cytoplasm of a type of cells quite comparable in structure to our vacuolated cells. As this phenomenon could be observed distinctly in various specimens, it became obvious that our cells may bc regarded as wandering cells, which had gained access to the fetal blood stream, and thereby constituted a portion of its white cells.” 
He also included a clearer figure with stained Hofbauer cells (HBCs) exclusively within his 1925 paper, which then goes on the delineate rapid increase in the number of HBCs in response acute infection. These kinds of morphological studies were common within Hofbauer's research. This indicates that the Hofbauer cells were being seriously considered to be macrophages as early as 1924/1925. [12]

Hofbauer Cells - 1925
Fig. 1: Section through normal villus at third month, showing Hofbauer cells.

Hofbauer also found that these cells reacted in a similar manner to a certain dye as other cells within the bone marrow and Kupffer cells, foreshadowing their future similarities as tissue-resident macrophages. [12]

Advertisement for Pituitary Extract featuring a glowing review by Hofbauer. [13] 

He was also one of the first gynecologists to utilize pituitrin, an extraction from cattle pituitary hormones, in order to help deal with labor pains. By the time the advertisement above was published, Hofbauer had applied the treatment to twelve patients and stated that "there were no unfavorable after-effects." [13] He recommended the product for "all forms of primary and secondary uterine inertia," noting that the introduction of these hormones has removed the need for many once common complex surgical procedures. [14] Reflecting in 1955 within his paper, Forty Years of Postpituitary Extract in Obstetrics, Hofbauer wrote the following [15]:
THE importance of the initial impulse that a fascinating experimental observation may inspire for its application to spheres of considerable practical interest is forcefully illustrated by the mosaic of significant advances which resulted from the report by H. H. Dale of vigorous contractions of the virgin guinea pig's uterus suspended in a neutral solution, induced by the addition of post-pituitary extract. Factual background data form the basis of the present attempt of an objective evaluation of the merits of post-pituitary preparations as a therapeutic standby, while an exhaustive review of the subject is not in the scope of this survey. 
The reflection above characters much of Hofbauer's research: a kind of try-and-see approach that attempted to find success and justified the original experiments with factual evidence afterwards.

Hofbauer also attempted to connect the human pituitary gland to the origins of cancer within mothers. He saw the cancer as a continued production of growth hormone that led to increased cell division. Although he was unable to link his theory to all cancers, Hofbauer successfully utilized X-ray radiology on the pituitary to help patients which was a precursor to modern radiation treatments. [16]

Character

Thomas F. Baskett wrote in his book, Eponyms and Names in Obstetrics and Gynaecology, that Hofbauer was "arrogant, egotistical and aggressive." Baskett recalls a story where Hofbauer told a junior colleague to write about their meeting in this manner: "Go home and write in your diary that today you talked to Hofbauer." [3]

Supplemental Image

Stained Placental Cross-Section by Hofbauer
Stained Placental Cross-Section by Hofbauer for Iron Absorption (1905)

References

1.
J. Isfred Isidor Hofbauer, http://hdl.handle.net/2193/5138JF11M.
2.
Times S to TNY. Dr. Isfred Hofbauer, a Gynecologist, 89. New York Times. 1961:39.
3.
Baskett TF. Eponyms and Names in Obstetrics and Gynaecology. 3rd ed. Cambridge University Press; 2019. doi:10.1017/9781108421706
4.
Österreichische Nationalbibliothek, ed. Handbuch Österreichischer Autorinnen Und Autoren Jüdischer Herkunft: 18. Bis 20. Jahrhundert. DE GRUYTER SAUR; 2002. doi:10.1515/9783110949001
5.
[Johns Hopkins Hospital Woman’s Clinic, circa 1924]. Flickr. Accessed May 28, 2020. https://www.flickr.com/photos/medical_archives/3570325755/
6.
Company P Davis &. Nuclein Therapy. Parke, Davis & Company; 1900.
7.
The Cincinnati Lancet-Clinic. J.C. Culbertson; 1904.
8.
Ames D. THE NATURE OF THE LEUCOCYTOSIS PRODUCED BY NUCLEINIC ACID; A PRELIMINARY EXPERIMENTAL STUDY. JAMA. 1897;XXIX(10):472. doi:10.1001/jama.1897.02440360016002e
9.
The American Journal of Obstetrics and Diseases of Women and Children. W.A. Townsend & Adams; 1903.
10.
Hofbauer Jsidro. Grundzüge Einer Biologie Der Menschlichen Plazenta, Mit Besonderer Berucksichtigung Fragen Der Fötalen Ernährung. W. Braumüller; 1905. Accessed May 28, 2020. https://catalog.hathitrust.org/Record/006744605
11.
Archives of Internal Medicine. American Medical Association.; 1923.
12.
Hofbauer J. The function of the hofbauer cells of the chorionic villus particularly in relation to acute infection and syphilis. American Journal of Obstetrics and Gynecology. 1925;10(1):1-14. doi:10.1016/S0002-9378(25)90514-5
13.
The Journal of the Arkansas Medical Society. Arkansas Medical Society.; 1912.
14.
Therapeutic Notes. Parke, Davis & Company; 1912.
15.
Hofbauer J. Forty Years of Postpituitary Extract in Obstetrics. American Journal of Obstetrics and Gynecology. 1955;69(4):822-825. doi:10.1016/S0002-9378(16)38084-X

16.
TIMES WLLS to TNY. GLAND INFLUENCE TRACED IN CANCER: Cell Growth Is Linked With Pituitary Overfunction in Cases of Mothers. CHECK BY X-RAY REPORTED Medical Association is Also Told of Many Infections Laid to Sinus Trouble. New York Times. 1934:16.

Is SO2 Polar or Nonpolar?

Answer: SO2 is a polar molecule because the lone pair of electrons on the central sulfur atom cause electron-electron repulsion that forces a bent structure leading to an unequal distribution of charge throughout the molecule. 

Due to the molecules relatively strong dipole, the compound a melting point of -72˚C and a boiling point of -10˚C. This means that SO2 is a gas at standard temperature and pressure. The gas is found at low concentrations in earths atmosphere at less than 1 ppm. It features more prominently on the atmospheres of other plants. For example, Venus has an atmospheric concentration of 150 ppm SO2. It can be produced from constituent elements or sulfites. The molecule is said to have a pungent smell- similar to a just-struck match. 


SO2 Ball and Stick
SO2 Ball and Stick Diagram (one of two resonance structures). Made with Avagadro.
How is SO2 utilized in the real world?

Sulfur dioxide is most commonly utilized as an intermediate in the production of sulfuric acid. It can be used as a preservative for dried fruits and it has played an important role ini wine-making for millennia. On a chemical note it serves as an excellent reducing agent in many reactions and biochemical systems. At lower temperatures it is also utilized as a solvent. It is a major air pollutant.

Is HCl Polar or Nonpolar?

Answer: HCl is a polar molecule due to the large electronegativity difference between Chlorine (3.16) and hydrogen (2.20). This causes a region of partial positive charge on the hydrogen atom and a region of partial negative charge on the chlorine halide. 

Typically the formula HCl can refer to one of two "concepts": the compound hydrogen chloride and hydrochloric acid, the aqueous form of hydrogen chloride. The compound has a melting point of -114˚C and a boiling point of -85˚C. This means that it is a gas at standard temperature and pressure. As mentioned the compound is soluble in water but it is also soluble in slightly less polar molecules such as ethanol and acetone. It is described as having a "pungent" odor. Hydrogen chloride has an in fact quite storied history being originally discovered by alchemists in the middle ages. Today it is recommended that HCl be handled with extreme caution as HCl forms a corrosive acid when inhaled or when in contact with any part of your skin.

HCl Ball and Stick Diagram
HCl Ball and Stick Diagram. Created with MolView.
How is HCl utilized in the real world?

Basically all of the prominent uses of HCl are for hydrochloric acid. This includes removing impurities from steel, as a reagent in the production of organic products utilized in pharmaceutical manufacturing, pH control and oil processing. The acid is also present within organism's digestive tract to support the process of degrading eaten foodstuffs.

Is CF4 Polar or Nonpolar?

Answer: CF4 is a nonpolar molecule due to the symmetrical tetrahedral structure which cancels out the different electron pulls by the extremely electronegative fluorine atoms. 

As a result of its nonpolar character carbon tetrafluoride has a melting point of -184˚C and a boiling point of -128˚C. This means that the compound is a gas at standard temperature and pressure. Due to the large electronegativity difference between fluorine (3.98) and carbon (2.55), the molecule is noted for an incredibly high bond strength. This is due to the partially positive carbon giving the molecular structure some ionic character. In fact carbon-fluoride bonds are noted to be the strongest bonds in organic chemistry. Tetrafluoromethane is naturally produced when you burn any carbon compound in an atmosphere of fluorine. In industrial applications the molecule is produced by combining CCl2F2 and HF.

CF4 Ball and Stick Diagram
CF4 Ball and Stick Diagram. Created with MolView.
How is CF4 utilized in the real world?

Due to the strength of the C-F bonds the compound is very stable and will only react with extreme elements like pure alkali metals. In industry the molecule is sometimes used as a refrigerant. Therefore CF4 is sometimes called R-14. As with many carbofluorides tetrafluoromethane can be used as a plasma etchant in this case specifically on silicon derivatives. Due to the molecules higher density it can also be utilized in neutron detectors. However these same properties make the structure one of the most persistent and potent greenhouse gases. The high density also means that CF4 will crowd our regular air, leading a risk of asphyxiation in poorly ventilated spaces.

Is CH2Cl2 Polar or Nonpolar?

Answer: CH2Cl2 is a polar molecule due to the unequal distribution of charge caused by the pull of electrons from the hydrogen atoms to the chlorine atoms due to hydrogen (2.20) have a lower electronegativity than chlorine (3.16). 

As a result of strong intermolecular forces caused by its polar properties, Dichloromethane has a melting point of -96.7˚C and a boiling point of 39.6˚C. This makes the compound a liquid at standard temperature and pressure. Although the liquid form is volatile, the compound is widely utilized as a solvent. Even though it does not form a solution with water, it can dissolve a wide variety of organic compounds which is why it is utilized as a solvent. CH2Cl2 is naturally produced in wetlands by macroalgae and in volcanic eruptions; however, the majority of the compound on earth is produced by humans in industrial processes. The structure is said to have a "sweet" aroma.

CH2Cl2 Ball and Stick Diagram. Created with MolView.
How is CH2Cl2 utilized in the real world?

In addition to being used as a solvent CH2Cl2 has been applied in the food industry to decaffeinate coffees and teas. The substance due to its low boiling point can extract mechanical energy from small temperature differences. Furthermore the compound can be used to weld certain plastics together. Although it is considered the least toxic of the simple chlorohydrocarbons, dichloromethane still poses serious health risks to overexposed individuals. Products with "DCM" are generally forced to label this on their packaging. It is believed that CH2Cl2 does not impact the ozone layer because it degenerates before reaching the stratosphere.

Is CH2O Polar or Nonpolar?

Answer: CH2O is a polar molecule due to the presence of a very electronegative oxygen (3.44) on one side of the molecule inducing a partial negative charge with the hydrogens carrying a partial positive charge due to hydrogen's lower electronegativity value (2.20).

Formaldehyde has a melting point of -92˚C and a boiling point of -19˚C as a result of its polar character. This means that the compound is a gas at standard temperature and pressure. It is also very soluble within other polar compounds such as water. Formaldehyde is mostly produced by processes in the upper atmosphere which account for 90% of its natural product. Processes such as forest fires and automobile exhaust systems also contribute CH2O to the environment. This molecule has also been found in interstellar space. There are many reactions involving formaldehyde within organic chemistry.

CH2O Ball and Stick Diagram
CH2O Ball and Stick Diagram. Created with MolView.
How is CH2O utilized in the real world?

The structure is a quite common precursor to many more complex molecules, including resins and finishes. There are a wide variety of niche uses as well including as a disinfectant and in photography. The compound is considered a human carcinogen at higher concentrations although your body naturally produces and requires a certain amount of formaldehyde. Certain countries have in fact banned manufacturing and importation of CH2O. There were also incidents in the 2000s where large quantities of foodstuff were contaminated in countries like Indonesia and Vietnam where the chemical was added to extent the shelf life of products.

Is CH3Cl Polar or Nonpolar?

Answer: CH3Cl is a polar molecule due to the partial negative dipole induced around the chlorine atom due to chlorine's high electronegativity (3.16) and the partial positive charges on each of the hydrogen atoms (electronegativity for hydrogen: 2.20). 

As a result chloromethane has a melting point of -97.4˚C and a boiling point of -23.8˚C. This means that the compound is a gas at standard temperature and pressure. This gas is often produced by the sugar cane industry during the burning of waste. When released it is said to have a lifespan of one to three years before decaying in the atmosphere. It also naturally occurs in marine phytoplankton and other kinds of bacteria which have an enzyme that synthesizes CH3Cl. It also also been detected as a trace gas in the interstellar space. It is described as having a "faint-sweet" odor.

CH3Cl Ball and Stick Diagram
CH3Cl Ball and Stick Diagram. Created with MolView.
How is CH3Cl utilized in the real world?

It was originally produced in 1835 by boiling a mixture of methanol, sulfuric acid and sodium chloride. This technique is still utilized today as chloromethane is widely utilized in reactions that produce compounds containing carbon, chlorine and silicon. It used to be within refrigerants. As a result the compound is also called Refrigerant-40. However this has been discontinued since the compound is labelled as a carcinogen with the same effects to the central nervous system as alcohol.