Teaching Resonance to Undergrads: How Hard Can It Be?

Posted on March 16, 2020 by | 3 comments

Resonance structures are a tough concept for chemistry students to understand, and the way they’re being taught has a significant impact on how well they retain the concept. A pair of researchers from the University of Nebraska and the University of Virginia’s Chemistry departments show that explaining the limitations of resonance drawings gives a better understanding than explaining the benefits.

 

The study, published March 13th of this year, took 180 students across 2 different organic chemistry classes with 2 different professors. The first professor focused on highlighting how accurate and beneficial resonance drawings are towards the understanding of the deeper chemistry. The second professor focused on the limitations and shortcomings of resonance drawings, and this approach gave a more accurate understanding of the underlying chemistry.

Reliability of Findings

Quantifying a student’s understanding of a concept is no easy task, so the researchers had to cover multiple facets of understanding. They asked students three questions relating to the underlying understandings of resonance contributors of enolates; written description of resonance hybrids, draw the resonance hybrids, and predict the carbon-oxygen bond length. The answers students gave are graphed below, and show that students in Professor 2’s class had a better understanding of all 3 concepts.

Examples of answers for students asked to draw an enolate resonance hybrid: (a) hybrid structure with correct partial charges (correct answer), (b) hybrid structure, (c) major resonance contributor, (d) minor contributor, and (e) example of other structures (incorrect). Source: Xue, D., Stains, M.

Students’ understanding of resonance hybrids between two professors analyzed through (a) written descriptions of the resonance hybrid, (b) drawings of the resonance hybrid, and (c) carbon-oxygen bond length predictions. Source: Xue, D., Stains, M.

This study did a great job of explaining the ways in which students can misunderstand resonance hybrids, and the pitfalls that professors need to stray students away from. However, teaching styles are not quantifiable, only qualitative observations can be made. This makes any differences possibly anecdotal. Further uncertainty is introduced by limiting the categories that a given student’s answer could fall under. This could “round up” some students to appear to understand more than they do, or vice versa.   Professor 2 also had 8 fewer students than Professor 1. This means Professor 1 had 109.4% the number of students that Professor 2 had, making the population sizes of the two groups significantly different in size.

Despite these possible problems with the methodology and certainty of this research, I think we can all empathize with how tough these concepts were at first. And to lighten the tone, I’ll share this analogy that Professor 2 used in his class to help his students learn. Hope it brings a smile to your face!

Analogy used by Professor 2 to teach about resonance. Source: Xue, D., Stains, M.

  • Griffin Bare

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New method found to build artificial blood vessels!

Posted on March 16, 2020 by | 4 comments

Figure1, yellow: Number of People died on the kidney transplant waitlist, blue: Number of people removed from the waitlist classified as “too sick”. Source

 

As the research shows, there are more than 114000 people in the United State on the waiting list of life-saving organ transplants. On average, there will be one new name added to the list every ten minutes, and 20 people die because of the lack of available organs every day. Research team from the University of Minnesota Medical School has published their new founding in Nature Biotechnology on March 11st, 2020. Their research proved the possibility to build artificial blood vessels in a pig, which has the potential to provide ultimate blood vessels for human organ transplants.

How did they come up with the idea?

“There is so many chronic and terminal diseases, and many people are not able to participate in organ transplantation,” said Daniel, a cardiologist who accepted heart transplantation before, “About 98 percent of people are not going to be eligible for a heart transplant, so there’s been a huge effort in trying to come up with strategies to increase the donor pool. Our approach looked at a pig.” Due to the physiological similarity between human and pigs, scientists have done similar studies of using pig insulin to treat human diabetes. These historical researches give scientists confidence and also an existing platform to study.

What is the benefit of choosing pigs?

Figure 2:Acute rejection Anti-CD3 Donor DC. Source

Transplant rejection is a process of transplanted tissue rejected by the recipient’s immune system. According to the research done previously, there are 50-80% of patients would have at least one rejection episode. This symptom is due to recipient’s body cannot adapt to a “foreign” tissue and the immune system would fight against the transplanted tissue. Transplant rejection always causes severe consequences, and a lot of patients would have to remove the tissue immediately.

Daniel Garry, the leader of the research team came up with an idea to avoid transplant rejection. They took mature cells scraped off from a patient’s skin, reprogram these cells and eventually inject them into a pig embryo. This process would develop patient’s own genetic information in pig’s body. Thus, patients will get their own “blood vessels” which can greatly avoid transplant rejection. Mary, coworker of Garry said: “These blood vessels would be engineered and could be utilized in these patients to prevent those kinds of life-long handicaps, if you will.”

The first phase of their study has been approved by the University of Minnesota’s Stem Cell Research Oversight committee. “While it is a first phase, there’s pretty solid proof of concept,” Mary said. “We believe that we’ve proven that there’s no off-target effects of these cells, so we’re ready to move forward to later gestational stages.” This study will eventually benefit millions of people who are suffering from transplantation surgery. Also, this study shines lights and give hopes to modern organ transplantation studies.

-Vicky Gu

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Symmetry in a single crystal – space group frequency

Posted on March 16, 2020 by | 1 comment

If you are the one who has experience of working in a synthetic laboratory, you might come across a single crystal. Have you ever noticed that the inner structure of the crystal is arranged symmetrically?

The symmetry of molecules, atoms, or ions in a single crystal

A single crystal does not grow randomly. It grows in an ordered manner so that a particle can have three-dimensional symmetry to another particle in the crystal. The symmetry between the particles is described as a space group. Easily speaking, the space group is a way to represent the spatial pattern of molecules, atoms, or ions in a single crystal. There are 230 space groups based on group theory, and a well-defined crystal structure shows one of the space groups.

Figure 1. An example of the space group “P 1 2 1” of a SiO2 crystal. The capital letter P stands for “primitive lattice”, the numbers 1 and 2 represent “1-fold and 2-fold rotation axes”, respectively. The left figure shows SiO2 molecules arranged in a unit cell and the unit cell is described as the Cartesian coordinates a, b, and c. The right figure shows the same unit cell with SiO2 molecules, but b axis is perpendicular to the screen. (Source: http://aflowlib.org)

Statistics of space groups

Molecules, atoms, or ions prefer to be arranged in a certain space group although they have 230 options. The database in Cambridge Crystallographic Data Centre (CCDC) contains more than one million crystal structures, and the number increases every day. The data centre reported that 986,061 structures show fully defined space groups. Interestingly, 34.4 % and 24.9 % of the structures have the space group “P 21/c” and “P -1”, respectively (Table 1). The key point is that more than 50 % of crystals, which you may come across in a laboratory, have particles arranged in either the space group P 21/c or P -1.

Table 1. Top 10 frequently occurring space groups. SG and CSD stand for space group and Cambridge structural database, respectively. (Source: CCDC, published in January 2019)

– Young Cho

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Surgery can activate cancer cells, but aspirin stops metastasis

Posted on March 15, 2020 by | Leave a comment

When patients are diagnosed with breast cancer, the cancer cells have already metastasized to another part of the body. However, the number of cancer cells involved in this process is negligible, and current equipment cannot detect them. Cancer cells after metastasis remain inactive, which seems unlikely to threaten patients’ health. Nevertheless, those dormant cancer cells are time bombs. One way to set them off, surprisingly, is through cancer surgery.

Recent research led by Dr. Robert Weinberg of the Whitehead Institute found the mechanisms that may explain why surgeries activate the hidden cancer cells. They designed a set of comparison experiments based on mice that injected with breast cancer cells and observed how breast cancer developed in different conditions.

To simulate the postoperative recovery process, scientists implanted sterile sponges in the mice injected with breast cancer cells. This “unnatural” design may be controversial, but it maintains all animals experiencing the same experimental conditions.

“Weinberg gets some pushback because he works on artificial systems, but this is often the only way to expose fundamental principles of biology.” said biologist Sui Huang, professor of the Institute for Systems Biology, who was convinced by this experiment.[1]

Figure 1. (A) Schematic illustrating the experimental design. Mice had been previously wounded by sponge implantation at one or two distant sites. (B) Tumor diameter during the one-month experiment. (C) Tumor incidence as a function of time (n = 9 to 10 per group) for the experimental and control group. Data are plotted as means ± SEM. P values were calculated using the Mann-Whitney test (P < 0.05). Source: Translational Medicine Science

One month after the surgery, researchers tested the number of cancer cells that remained in mice’s bodies. Figure 1 summarizes the results: for those that accepted the surgery, 60% of mice developed tumors in other parts of the body. While in the comparison group, the value is only 15%. Based on the results from 270 mice, Weinberg concluded that surgery could accelerate the cancer cell metastasis and even facilitate tumor formation.

The reason for the effect, as explained in the paper, has to do with the immune system. During the surgical wound recovery process, the inflammatory response restricts the immune system. Therefore, the “guard cells” cannot effectively monitor the cancer cells, resulting in metastasis and tumor formation.

Figure 2. Tumor diameter after the injection of cancer cells into previously unwounded (left) or wounded (right) mice treated with saline or meloxicam (n = 15 mice per group). Data are plotted as means ± SEM. P values were calculated the Mann-Whitney test P < 0.0005. Source: Translational Medicine Science

The good news is common pain killers, such as aspirin, can efficiently inhibit this process. Scientists found that many nonsteroidal anti-inflammatory drugs can effectively suppress tumor formation resulting from surgical wounds. Figure 2 shows that the wounded mice had a constant tumor size at around 2mm after given meloxicam, while the comparison developed tumors at average 5mm. Note the experiment only tested meloxicam; aspirin was also proved to be effective in the follow-up research.

Although the results are quite delightful, whether we can apply the same experiment to humans remains unclear. Weinberg pointed out that the aim of the investigation is not telling people not to trust lumpectomy or other tumor surgeries but develop a more effective treatment for postoperative recovery. He hoped that this research would promote further experiment on human and test whether drugs like aspirin has the same effect in the human body.

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What is N95? ——The knowledge about face masks

Posted on March 3, 2020 by | 2 comments

Facing the outbreak of the new coronavirus, all kinds of face masks were sold out in the blink of an eye. More and more people seem to start to realize the importance of face masks.  But, do face masks really work? and how they work?

The answer largely depends on what type of face mask you are wearing.

Classification of Face Masks

According to the design of the face masks, the general ranking of the protective ability is (high to low): N95 masks> surgical masks> ordinary medical masks> ordinary cotton masks. But in the case of the new coronavirus, the most effective type of face masks are medical-surgical masks and masks filtering 95% or more of non-oily particles, such as N95, KN95, DS2, FFP2, etc. At present, China’s medical face masks are mainly divided into three types: medical protective masks with the highest protection level, medical-surgical masks commonly used in invasive operating environments such as operating rooms, and ordinary disposable medical masks.

 

How Face Masks Work?

Usually, medical face masks are made of non-woven fabrics, and its raw materials are mainly Polypropylene. And polypropylene layers are arranged to form an SMS structure.

SMS structure makes face masks capable to block floating particles while allowing airflow in and out the face masks. In this structure, the key material that brings the virus filtering effect is a high density, electrostatic layer lies in the middle: melt-blown non-woven fabric. When small particles like viruses get close to the melt-blown nonwoven fabric, it will be immediately captured by the electrostatic field and adsorbed on the surface of the non-woven fabric, and therefore prevent the virus gets into the body.
Yicheng Zhu

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Enhancing Car Components – Car Bonnets Fabricated Using a Short-Carbon-Fiber-Reinforced Polypropylene Composite

Posted on March 3, 2020 by | Leave a comment

In the automotive industry, the integration of composite materials into the fabrication of certain car components has become increasingly popular. Particularly in the case of forming lighter components. Car manufacturers have been developing novel and innovative materials in the pursuit of weight reduction, where they have achieved it using short-fibre reinforced polymer (SFRP) composites.

Mansory Carbon Fiber Bonnet                                  Source: Mansory Copyright: 2020 Mansory Design & Holding GmbH

As the name suggests, SFRPs are composite materials with short length fibers that are discontinuous. This composite is easy to synthesize and has excellent mechanical properties, making it quite an interesting, yet practical, material. Furthermore, incorporating carbon short fibers is advantageous, as it is light, corrosion-resistant and quite cheap.

With the backing from the Standard and Industrial Research Institute of Malaysia (SIRIM) and Ministry of Science, Technology, and Innovation (MOSTI) in Malaysia, Rezaei et al. were able to formulate and characterize short-carbon-fiber-reinforced polypropylene (SCF/PP) composites, with the intention of replacing the more traditional steel bonnet.

To synthesize the SCF/PP, the researchers used Titanpro SM950 Polypropylene Copolymer as their matrix and Composite OracleTM, Torayca T700S 12 K acted as their reinforcing carbon fiber. They were then able to prepare 5 composite samples of varying carbon fiber sizes by blending the short carbon fiber and polypropylene. Pellets of the material were then formed and subsequently pressed. This technique is a common method used to generate carbon-fiber-reinforced-thermoplastics. Density tests and Thermogravimetric analysis (TGA) were two techniques used to characterise the material. These properties are important factors that need to be considered when making a bonnet.

From the density test data, it is evident that the composite density increased with increasing fiber content used. This was expected since the density of CF (1.80 g/cm3) is greater than the PP (0.89 g/cm3). However, the composite density decreased with the increase in the CF length. The graph below illustrates this trend for 7% CF content.

Figure 1. Effect of CF size on the density of SCF/PP composites

One proposed explanation is that there is a reduction in the voids and vacuoles, which allows the composite to pack more tightly. However, they also suspect that there is a better distribution of short fibres embedded within the PP framework, which is likely to reduce the number of voids.

The TGA data is important as it is often used in the determination of the end use. From the data, it is evident that the introduction of CF fibers to the PP matrix, improved composites ability to withstand degradation. Furthermore, heat was used to begin the degradation processes and the overall structure was either ruptured or split. The graph below depicts the degradation of the samples with 7% fiber content.

Figure 2. TGA curves of composites with 7% fiber content

As more CF is added to the PP matrix, the heat absorption capacity of CF is higher than that of PP and thus the composite will withstand degradation. Furthermore, the data suggests that as the lengths of fibers increased, the fibers in the composites absorbed more heat.

These two properties and the relative ease of forming SCF/PP composites demonstrate the efficacy and effectiveness of the material in the fabrication of a bonnet.

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Calculating Decay Rates for Double-Proton Emission

Posted on March 3, 2020 by | Leave a comment

Double-proton emission has motivated great interests in nuclear and radiochemistry due to its extremely rare occurrence. This decay mode first appeared only as a prediction from theories on nucleon pairing; it involves the simultaneous emission of two protons in proton-very-rich nuclei, where competing single-proton emission is quantum-mechanically forbidden. Since 2002, double proton-emission was observed in experiments, but they still lacked a coherent and accurate theoretical framework.

Double-Proton Emission (made with blender/photoshop)

The group of researchers led by M. Goncalves have recently calculated the decay rate for double-proton emission, filling the missing theoretical gap. The rate of decay is fundamental to the quantification of nuclear reactions; theoretical decay rates from this research will provide the basis for future double-proton reaction designs.

Nucleons are massive and inert to physical conditions, thus nuclear reactions are only quantified statistically using special relativity and quantum mechanics. To tackle this, the researchers used the effective liquid drop model, widely used in alpha decay and cold fission calculations. This model assumes that nucleons interact with each other like particles in a droplet of water.

Liquid Drop Model
(Source:People’s University, Bhopal)

From known values of mass excess, coulomb’s barrier, and dimensional parameters, the researchers calculated the double-proton emission half-life for nuclides mass below 70u. The log of half-life is then plotted against parameter q, derived from the decay energy of each nuclide.

The available experimental double-proton emission half-lives for 16Ne, 19Mg, 45Fe, 48Ni, 54Zn and 67Kr are then plotted on the graph. The experimental values matched closely with the theoretical calculations, except 16Ne; a possible explanation for the deviation may be its mass number away from nuclear magic numbers.

When not using a log variable, the differences between experimental and

theoretical values seem significant. Nevertheless, in the field of nuclear science, this scale of difference is already near-perfection; even the best models such as SEME shows a deviation above 4-times for nuclear binding energy calculations.

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Is the World Set to Run Out of Cobalt?

Posted on March 2, 2020 by | Leave a comment

Cobalt is an important part of most batteries, and our global supply is running low. The demand of cobalt in the next 10 years is expected to increase by roughly 300%, and a team of researchers from the Massachusetts Institute of Technology decided to investigate exactly how much of a problem this increased demand could be.

Lithium-ion batteries, such as the ones found in electric cars and most smart phones, require a cathode for the battery to operate, and cobalt is the most common choice due to having a high energy density compared to its competitors. The study focuses on the amount of cobalt we are mining and processing now compared to how much we will need by 2030. By their estimates, the world may require 450 k tonnes per year in cobalt.

Values interpolated from research data. Source: Fu et al.

The researchers employed a methodology of analyzing market trends in the sales of electric cars, which account for roughly 60% of all cobalt use. To determine the amounts of cobalt production, they surveyed mining companies to determine the amount of cobalt being produced in cobalt mines, and as a by-product in non-cobalt mines. With these values as their main metrics, they made projections for the next decade with the hopes of seeing if, and when, our cobalt might run short.

 

The methodology is not perfect, however; it is a forecast and not a guaranteed trend. Thus, the data presented is largely extrapolated and estimated from general trends. But the goal of the paper was not to draw exact conclusion. Their goal was to investigate how sustainable this resource is in the short term.

 

The main take-away from their paper are that end-of-life reclamation of cobalt-reliant materials is going to start being more and more necessary. So even with all of our new technologies, the message of sustainability stays the same: Reduce, Reuse, Recycle!

Griffin Bare

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Revolution of Orthopedic Surgery – Bioactive Glass Composite Pore-forming Strategy

Posted on March 2, 2020 by | 1 comment

The use of adhesives to replace traditional invasive internal fixation tools (such as steel plates and nails) will revolutionize orthopedic surgery. The ideal bone cement should be able to immediately fix the fracture site, while providing a space and microenvironment suitable for bone cell growth and promoting fracture healing.

Cyanoacrylate (commonly known as universal glue) is currently the only medical glue with excellent instant adhesive strength and biocompatibility, but its polymerization product is non-degradable and cannot support the growth of new bone tissue through the adhesive layer, which hinders Because of bone healing, it cannot yet be used as a bone cement.

Recently, with the support of the Ministry of Science and Technology, the National Natural Science Foundation of China, and the Chinese Academy of Sciences, Qiu Dong’s group at the has proposed a bioactive glass composite pore-forming strategy to help cyanoacrylate bonding Agents are used for internal fixation of fractures to promote fracture healing. Bioactive glass has excellent osteoconductivity, osteoinduction, and can promote the regeneration of bone tissue.

To prove that the bioactive pore‐forming adhesive is not only strong and instant bonded but also facilitates cell ingrowth and displays excellent bioactivity, they conducted bone‐fracture healing experiments. In the experiment, the bioactive pore‐forming adhesive (PSC1/PEG4/OCA5) was compared with commercial adhesive (OCA) and pore‐forming adhesive (PEG5/OCA5) by applying all to a circular bone piece which was fixed within freshly formed cranial fractures in a group of mice.

Figure 1. The scheme of a mouse cranial fracture with the craniotomy location (Source)

The stability of the circular bone piece and bone healing effect were evaluated at 12 weeks post‐operation. The ratio of bone volume (BV) within the circular gap over the total volume (TV) within the circular gap was quantified as shown in the figure 2 below. After 12 weeks, BV/TV of the PSC1/PEG4/OCA5 group was 0.76 ± 0.06, which was significantly higher than that of the PEG5/OCA5 group (0.47 ± 0.10), the OCA group (0.40 ± 0.06), and the group with no adhesive treatment (0.26 ± 0.05). These findings supported that the adhesive with pores for bone ingrowth was crucial for new bone formation.

Figure 2. quantitative analysis of new bone formation (Source)

ARS (Alizarin Red S) can detect calcium which is a characteristic evidence to bone‐like structures. As shown in Figure 3, the Ca content in the bioactive pore‐forming adhesive (OD = 0.084 ± 0.008) was around two-fold higher than those in the merely pore‐forming adhesive (OD = 0.046 ± 0.004) and CA adhesive (OD = 0.041 ± 0.001). As a result, these findings were consistent with the statement that the PSC BG can promote osteogenic differentiation that is of importance for bone regeneration.

Figure 3. The optical density of eluents from ARS‐stained adhesives (Source)

The bioactive bone cement has good clinical transformation prospects and can provide new ideas and methods for clinical fracture treatment. At the same time, the above-mentioned composite pore-forming strategy can also be used for substances other than bioactive glass to increase matrix materials and functions. Material compatibility.

 

-Xinyue Yang

Posted on Mar.2nd, 2020

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Deep Brain Stimulation on Patients with Parkinson Disease

Posted on March 2, 2020 by | Leave a comment

Deep Brain Stimulation (DBS) is a form of neurological stimulation and is used as a form of treatment for those suffering from Parkinson’s Diesease (PD). PD is a neurodegenerative brain disorder which hinders dopaminergic neurons, resulting in impaired mobility. DBS involves a surgical process of implanting a small battery operated device and a electrodes into the brain.

Figure 1 – Deep Brain Stimulation Retrieved from – GAPS

This study published in August 2006 highlights the efficacy of DBS. 156 patients were randomly paired (78 pairs) and were subjected to different treatments. One was subjected to treatment from pharmaceuticals and the other underwent DBS. To test the efficacy of DBS, the patients’ quality of life was assessed using the Parkinson’s Disease Questionaire (PDQ-39). Additionally, numerous symptoms associated with PD were measured using the Unified Parkinson’s Disease Rating Scale, part III (UPDRS-III).

Efficacy of DBS

Out of the 78 pairs of patients, the patient who underwent DBS in 50 of the pairs saw an improvement in their PDQ-39 and UPDRS-III scores compared to their partner who was only provided with pharmaceutical drugs.

Figure 2 – How DBS and Pharmaceuticals affected the PDQ-39 and UPDRS-III scores in patients immediately after treatment. In 50 of the 78 pairs, those who underwent DBS showed improvement in their scores compared to their partners who took medication. Data from Deuschl et al.

Furthermore, the patients were assessed again in six months. Those who underwent DBS saw a 25% increase (a lower score) to their PDQ-39 score, while there we no significant changes to those who took medication.

Figure 3 – PDQ-39 Scores immediately after treatment (baseline), and 6 months after treatment. Error Bars represent standard deviation. Data adapted from Table 3 of Deuschl et al.

Benefit of DBS Compared to Medication on Treating Depression

There are additional benefits of DBS on other aspects of PD. This study published in March of 2005 highlights how DBS is able to treat depression, which is a symptom associated with PD. Patients who were treated by DBS noted a decrease in depression-like symptoms 1 month after treatment, and up to 1 year. In contrast, medication can only treat depression in the short-term.

Figure 4 – A visual interpretation of depression Retrieved from – ConsumerReport

So why is DBS better than Prescription Medication?

The results of both studies indicate that DBS is capable to treating PD with a higher efficacy compared to medication. Additionally, medication is kept constant and can be used to treat one specific issue. In contrast, the strength of DBS can be altered (stronger/weaker pulses) to treat different symptoms that may arise. Consequently, DBS results in long-term benefits, while medication is only able to provide short-term benefits.

-Jackson Kuan

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