Steve P. Janagap
Department of Chemistry
College of Arts and Sciences
UP Visayas
Application of experimental design and multivariate analysis in the on-line reaction monitoring of a Suzuki cross-coupling reaction by Raman spectroscopy, Vibrational Spectroscopy, 100, 93-98
In this study, the amount of a chemical product from a chemical reaction was measured. The amount of product produced at specific time intervals and varying experimental conditions (temperature of the reaction and concentration of one of the ingredients) was determined using conventional instrumental methods and Raman method. The data from both the conventional and Raman methods were used in building a mathematical model that could predict the amount of the product in the reaction. The predictive model was then validated and results showed that it could measure accurately the amount of the product via the Raman method alone.
The prediction of the model was also tested using samples that were run using new experimental conditions – temperature and concentration values that were outside the normal range were used. Validation experiments showed that the predicted amounts of product were still accurate using the mathematical model that was developed. The study showed that there is no need to perform conventional instrumental methods once a predictive model is established and validated. This could greatly save time and resources in monitoring chemical reactions.
Significance:
This research is important in monitoring synthetic chemical reactions without interrupting the reactions. One would be able to predict the reaction yield using a prediction model, which is derived from the results of sets of experiments that were conducted at different conditions. With the developed method, there is no need to take out samples to determine whether the product is formed or not. With the use of mathematical model, the reaction product could be quantitatively determined on-line.
Link to the article: https://www.sciencedirect.com/science/article/pii/S0924203118303151
Impact factor: (2017/2018) 1.363
Jay Jomar F. Quintos
College of Humanities and Social Sciences
UP Mindanao
“An Babae ug Suba: Ang Talinghaga sa Anyo ng “Babae-sa-Tubig” sa Tradisyong Pampanitikan sa Pilipinas” (An Babaye ug Suba: The Trope of the “Woman-by-the-Water” in Philippine Literary Tradition). Humanities Diliman. (July to December 2018) 15:2, 93-119
This research work looks into the recurring “Woman-by-the-Water” image in Philippine literary and cultural traditions. It surveys the scant of extant materials available—sources across the country and in various genres and timeframes—about the trajectory of the image. If the Philippine indigenous belief systems through epics and narratives have always featured the “Woman-by-the-Water” as bold and robust, it was wrought by the different colours and shapes of colonizations. In the colonial literary texts such as “Ang Alamat ni Mariang Makiling” (Luzon), “The Legend of Maria Cacao” (Visayas), and “Ang Parang Sabil nina Abdulla at Putli’ Isara” (Mindanao), the “Woman-by-the-Water” has turned into being emotionally-laden, weeping, and vengeful. Thus, the analyses of the socio-political, cultural, and economic factors that affect and influence these transformations. Finally, this research work tries to weave the precolonial, colonial, and geocolonial worlds of a nation that is contoured, imagined, and embodied by troves of tropes and metaphors.
Significance:
The research work titled “An Babae ug Suba: Ang Talinghaga sa Anyo ng “Babae-sa-Tubig” sa Tradisyong Pampanitikan sa Pilipinas” (An Babae ug Suba: The Trope of the “Woman-by-the-Water” in Philippine Literary Tradition) is a valuable contribution to the disciplines of folk and Visayan-Mindanao studies. On one hand, it explains the ecological reasons for “water” and “women” as significant realities in Philippine cultures and societies; and on the other hand, it both articulates and traces the trajectories and transformations of the “woman-by-the-water” image from its precolonial origins upto its geocolonial imaginings.
Link to the article: http://www.journals.upd.edu.ph/index.php/humanitiesdiliman/article/view/6456
Impact factor: Not yet available
Jerico B. Bacani
Department of Mathematics and Computer Science
College of Science
UP Baguio
Class of Admissible Perturbations of Special Expressions involving Completely Monotonic Functions, Italian Journal of Pure and Applied Mathematics, N. 40-2018, 410-423
Read summary and significance here.
Link to the article: http://ijpam.uniud.it/online_issue/IJPAM_no-40-2018.pdf
Impact factor: Not yet available
David Emmanuel M. General
Museum of Natural History
UP Los Baños
A preliminary assessment of bumble bee (Hymenoptera: Apidae) habitat suitability across protected and unprotected areas in the Philippines. Annals of the Entomological Society of America XX(X):1-6. doi: 10.1093/aesa/say046
The two species of bumble bees in the Philippines are very poorly studied, perhaps because researchers don’t know where to look for these bees. In this paper, we compared the known locality records of these bees with seven bioclimatic or environmental variables, eg., annual mean temperature, to estimate suitable areas for the bees. These areas of habitat suitability, whether in protected areas or not, are presented in maps. Future field work to survey these bees should prioritize the areas of high habitat suitability.
Significance:
This study presents our preliminary assessment of habitat suitability of both protected and unprotected areas in the Philippines for the two known bumble bee species. We provide maps indicating known localities (from museum specimens) and areas of varying suitability. Areas of high habitat suitability may then be prioritized for surveys of bumble bees, with the possible improvement of our understanding of bumble bee distributions and ecology.
Link to the article: https://academic.oup.com/aesa/advance-article/doi/10.1093/aesa/say046/5214003?guestAccessKey=26d03d2c-94bf-4c52-83b1-972c05467510
Impact factor: (2017/2018) 1.558
David Emmanuel M. General
Museum of Natural History
UP Los Baños
Odontomachus ferminae, a new Philippine species of the infandus species group (Hymenoptera, Formicidae). Halteres 9, 157-162
This paper describes a new species of the genus Odontomachus, the true “hantik” ants, known for their fierce aggressive behavior and painful sting. There are now 11 species of this genus known from the Philippines. This number of species implies that the ant diversity of the Philippines is very high, considering that the genus Odontomachus is only one of the 100 ant genera that can be found in the country. This new species appears to be restricted to the island of Sibuyan, hence it is imperative to conserve its home and habitat. This new species is also interesting because it is similar in size and color to the weaver ants, which are erroneously but commonly referred to also as “hantik”. This mimicry system benefits both members because a predator that learns a painful lesson from one ant species will also avoid the mimic.
Significance:
This paper describes a new species of the genus Odontomachus from the Philippines, bringing the number of species to 11. This number indicates the high diversity of ants in the Philippines, considering that the genus Odontomachus is only one of 100 ant genera known from the Philippines.
Link to the article: www.antdiversityindia.com/yahoo_site_admin/assets/docs/Odontomachus_ferminae_upload.272210551.pdf
Impact factor: Not yet available
David Emmanuel M. General
Museum of Natural History
UP Los Baños
Revision and redefinition of the crematogastrine ant genus Tetheamyrma Bolton, 1991, with the description of a new species and the first description of the dealate queen (Hymenoptera: Formicidae). Myrmecological News 28: 45-51
The ant genus Tetheamyrma used to contain only one species, known from Sabah, Malaysia. But a recent molecular study found that an undescribed ant species from the Philippines belongs to this genus, even though this species did not look like it belonged to the genus. The genus is redefined to include this new species, now named Tetheamyrma bidentata General and Buenavente, 2018. The genus is also revised when all the known species are included in the study. An identification key is included to allow students and researchers to identify the specimens they may have collected. Finally, a map of all the locations where Tetheamyrma ants have been collected is presented.
Significance:
This paper revises and redescribes the ant genus Tetheamyrma. This genus was previously monotypic, meaning there was only one species in the genus. A recent molecular (DNA) study found that an undescribed Philippine species belonged to this genus, even though there were many morphological differences. Since the molecular study is very robust and strongly supported by statistical analysis, then the unknown species must be a member of the genus. This finding required the redefinition of the genus, to include the morphological characters that vary between the two known species. The genus is also revised, when all the known species are included in the study.An identification key to the species of Tetheamyrma will allow students and researchers to identify the specimens which they may collect.
Link to the article: https://biotaxa.org/mn/article/view/42173
Impact factor: (2017/2018) 1.838
Michelle Sunico Segarra
Clinical Dental Sciences
College of Dentistry
UP Manila
Effect of sodium fluoride pretreatment on the efficacy of an in-office bleaching agent: An in vitro study. Clinical and Experimental Dental Research, 4(4), 113–118. https://doi.org/10.1002/cre2.113
Color change after bleaching between control group and NaF group
Typical color change at each bleaching step
This study evaluated the effect of fluoride on the whitening or bleaching ability of an in-office (dentist-applied) tooth whitening agent. Fluoride is a common agent used to prevent or manage the most common side effect of bleaching which is tooth sensitivity. However, the manufacturer of this tooth whitening product does not recommend the use of fluoride as it believes that it will interfere with the tooth whitening process. This study aimed to see whether fluoride applied before bleaching would interfere with the bleaching procedure.
Twenty bovine teeth were prepared and stained with black tea to simulate staining in the mouth. They were divided into two groups (control and experimental) of 10 teeth each. In the control group the stained teeth were merely immersed in distilled water for 30 minutes while in the experimental group, the stained teeth were treated with 0.2% fluoride for 30 minutes. The specimens were then bleached with the whitening agent for 10 times. The whitening effect of the bleaching agent were compared using a dental colorimeter, a device which measure changes in color, after every tooth whitening or bleaching cycle. The teeth lightened in color for both experimental and control group. There was no difference in the whitening effect in teeth with and without fluoride application. Therefore, the application of fluoride prior to the bleaching procedure did not interfere with the bleaching effect.
Significance:
This work is significant in the field of esthetic and restorative dentistry. As more and more people are opting for whiter teeth, controlling the side effects of tooth bleaching and which means of preventing or managing these side effects can interfere with the effectiveness of the bleaching procedure are important factor in vital tooth bleaching procedure. This paper will help guide clinicians in choosing the appropriate bleaching material and technique.
Link to the article: http://doi.wiley.com/10.1002/cre2.113
Impact factor: Not yet available
Anna Lena Lopez and Peter Francis Raguindin
Institute of Child Health and Human Development
National Institutes of Health
UP Manila
Impact of rotavirus vaccine on diarrheal hospitalization and outpatient consultations in the Philippines: First evidence from a middle-income Asian country. Vaccine 36, 3308-3314
Rotavirus (RV) is one of the most common cause of diarrhea in children. Currently, RV vaccines are available to prevent infection. However, RV vaccines are not yet given routinely for babies in the Philippines, as the policy-makers are still requiring additional proof on its benefit. We recorded the number of diarrhea in an area where rotavirus vaccine was given to infants (Agusan del Sur), and compared to an area where no vaccine was given (Cotabato City). In this study, we prove that RV vaccine-use in the community results in a decline in the total number of diarrhea, not only among the vaccinated children, but also among the unvaccinated group. Our results, therefore, support the use of the vaccine for routine immunization program in the Philippines.
Significance:
1. Starting in 2012, Rotavirus vaccine (RVV) was introduced in public health clinics of Agusan del Sur province.
2. Declines in diarrheal hospitalizations and consults were seen following RVV introduction.
3. No declines in diarrheal admissions were observed in a province where RVV was not introduced.
4. This is the first evidence of the public health impact of RVV in a middle income country in Asia.
Link to the article: https://www.sciencedirect.com/science/article/pii/S0264410X18305553
Impact factor: (2017/2018) 3.285
Geraldine Zamora Racaza
Department of Medicine
College of Medicine
UP Manila
A multi-group confirmatory factor analyses of the LupusPRO between southern California and Filipino samples of patients with systemic lupus erythematosus. Lupus 2017 January 1: 961203316686706
The LupusPRO is a comprehensive, self-report measure developed specifically for populations with SLE, which assesses both health-related quality of life and non-health related quality of life. Given its increasingly widespread use, additional research is needed to evaluate the psychometric integrity of the LupusPRO across diverse populations. We aimed to evaluate the performance of the LupusPRO with its 12 subscales in two divergent patient samples (136 patients from an ethnically-diverse, urban region in southern California and 100 from an ethnically-homogenous, rural region in Manila, Philippines). After analysis we found that despite significant sociodemographic and clinical differences between the two samples, for the most part, the LupusPRO performed similarly in both samples and is a potentially useful tool our patients with SLE can use to assess their conditions.
Significance:
My researches involved collaboration with colleagues from Cedars-Sinai Medical Center (CSMC) and University of California Los Angeles (UCLA) wherein we were able to compare several attributes of patients with systemic lupus erythematosus in the Philippines and Southern California. We delved on the oft-neglected importance of psychosocial influence on somatic disorders, and tried to check for associations with disease activity, socio-econonic status, as well as strength of social support. We found that, indeed, there are racial and geographic differences in many of these factors, and these likely influence the disease and outcomes in patients. Many of these may be addressed to improve patient outcomes.
Link to the article: http://journals.sagepub.com/doi/abs/10.1177/0961203316686706?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed
Impact factor: (2017/2018) 2.969
Geraldine Zamora Racaza
Department of Medicine
College of Medicine
UP Manila
The psychometric properties of the Perceived Stress Scale-10 among patients with systemic lupus erythematosus. Lupus. 2017 Oct;26(11):1218-1223. doi: 10.1177/0961203317701844. Epub 2017 Apr 13
SLE is a potentially debilitating chronic disease and it is important to establish the significance of stress in this disease. A scoring system, the Perceived Stress Scale-10, has been used in different conditions but has yet to be psychometrically evaluated in patients with SLE. An analysis was used to examine the validity and usability of this scale among patients with SLE (N = 138) receiving medical care at Cedars Sinai Medical Center. We found that the scoring system was valid and had significant correlations with anxiety, depression, and helplessness, while there were no significant correlations with the subjects’ SLE disease activity. The Perceived Stress Scale-10 can be used to examine perceived stress among patients with SLE to assess need for intervention for overall improved outcome.
Significance:
My researches involved collaboration with colleagues from Cedars-Sinai Medical Center (CSMC) and University of California Los Angeles (UCLA) wherein we were able to compare several attributes of patients with systemic lupus erythematosus in the Philippines and Southern California. We delved on the oft-neglected importance of psychosocial influence on somatic disorders, and tried to check for associations with disease activity, socio-econonic status, as well as strenght of social support. We found that, indeed, there are racial and geographic differences in many of these factors, and these likely influence the disease and outcomes in patients. Many of these may be addressed to improve patient outcomes.
Link to the article: http://journals.sagepub.com/doi/abs/10.1177/0961203317701844?journalCode=lupa
Impact factor: (2017/2018) 2.969
Geraldine Zamora Racaza
Department of Medicine
College of Medicine
UP Manila
The meditational role of helplessness in psychological outcomes in systemic lupus erythematosus. Lupus. 2018 Jun;27(7):1185-1189. doi: 10.1177/0961203317751046
Systemic lupus erythematosus (SLE) is a lifelong illness that can result in pain, disability and psychological distress including anxiety and depression. Our team theorized that helplessness (the state or feeling of not being in control of one’s or any life situation or ailment) may be the potential link between pain from having SLE and their psychological distress. An analysis was used to test this theory in a sample of patients with SLE (N = 136) receiving medical care at Cedars Sinai Medical Center. We found that indeed, participants reported a high level of inability to control one’s disease. Helplessness fully mediated and bridged the relationship between pain and anxiety, depression, and perceived stress among patients with SLE in this community. This then becomes a possible target for intervention to improve patient outcomes.
Significance:
My researches involved collaboration with colleagues from Cedars-Sinai Medical Center (CSMC) and University of California Los Angeles (UCLA) wherein we were able to compare several attributes of patients with systemic lupus erythematosus in the Philippines and Southern California. We delved on the oft-neglected importance of psychosocial influence on somatic disorders, and tried to check for associations with disease activity, socio-econonic status, as well as strenght of social support. We found that, indeed, there are racial and geographic differences in many of these factors, and these likely influence the disease and outcomes in patients. Many of these may be addressed to improve patient outcomes.
Link to the article: http://journals.sagepub.com/doi/abs/10.1177/0961203317751046?journalCode=lupa
Impact factor: (2017/2018) 2.969
Cristina E. Torres, Edlyn B. Jimenez and Jacinto B. V. Mantaring
National Institutes of Health
UP Manila
What information and the extent of information research participants need in informed consent forms: a multi-country survey. BMC Medical Ethics, 19(1). https://doi.org/10.1186/s12910-018-0318-x
The study aimed to identify the elements and the extent of information in informed consent forms that research subjects in biomedical research would like to know prior to research involvement. The design uses a cross sectional survey conducted in 54 clinical research units or comparable settings of the participating centers in seven FERCAP-member countries (India, Indonesia, Malaysia Philippines, Sri Lanka, Taiwan, and Thailand). The results indicated that majority of respondents considered the contents of standard informed consent forms to be “moderately important” to “very important” to their decision, especially risks, directs benefit, and common adverse effects of the research procedures.
Link to the article: https://bmcmedethics.biomedcentral.com/articles/10.1186/s12910-018-0318-x
Impact factor: (2017/2018) 1.969
Nicole Bernardo Aliling and Paul Matthew Pasco
Department of Neurosciences
College of Medicine
UP Manila
Repetitive transcranial magnetic stimulation for post-stroke dysphagia: a meta-analysis. Acta medica philippina. 2017;(51)4:327-333
Stroke is a condition resulting from damage to blood vessels in the brain, as a result of either vessel blockage leading to infarction, or vessel rupture causing hemorrhage. It is the second leading cause of death, and the top cause of disability in the Philippines. One of the complications that patients who survive having stroke, is dysphagia or difficulty in swallowing. Current methods available for swallow rehabilitation are helpful, but none of them assure complete recovery.
Repetitive transcranial magnetic stimulation or rTMS is a procedure done using a machine containing magnetic coils that stimulate specific areas of the brain. We examined studies that used rTMS to target the part of the brain cortex responsible for swallowing. The pooled results of these studies showed that rTMS is a viable option to add in the repertoire of methods used for swallow therapy.
Significance:
Dysphagia is one of the prominent causes of morbidity and mortality among patients who suffered from stroke. The role of repetitive transcranial stimulation (rTMS) as an adjunctive modality to supplement traditional methods of swallowing therapy for these patients was evaluated in our study.
Link to the article: http://www.actamedicaphilippina.org
Impact factor: Not yet available
Jose Danilo Bengzon Diestro and Abdelsimar Tan Omar II
Department of Neurosciences
College of Medicine
UP Manila
Chiari Malformation and Tuberculous Meningitis: Aetiology and Management. BMJ Case Report, doi: 10.1136/bcr-2018-224245, 2018
This is the first reported case of Chiari 1 malformation (CIM) in association with Tuberculous (TB) Meningitis. CIM is a known congenital anomaly that causes part of the brain to protrude through an opening at the base of the skull. Our case associates the anomaly with a common neuroinfectious disease, TB meningitis. Our patient presented with a 2-week history of fever, headache and vomiting because of increase pressure in her brain. Prior to treatment her severe dizziness and unstable walking confined her to the bed. She underwent surgery for the CIM to decompress her intracranial vault and relieve the pressure caused by the part of the brain blocking the outflow of brain fluid. After surgery she was treated for TB meningitis with oral medications. Four years after she was discharged she is now able to stand independently and ambulate with an assistive device. She is still able to support herself by establishing an online clothes shop.
Significance:
The research brings to light a rare variant of Chiari Malformation—an acquired type from tuberculous meningitis.
Link to the article: doi: 10.1136/bcr-2018-224245
Impact factor: Not yet available
Jose Danilo Bengzon Diestro, Mark Angelo C. Ang, Mark Willy L. Mondia and Paul Matthew D. Pasco
Department of Neurosciences
College of Medicine
UP Manila
Validation of a Questionnaire for Distinguishing X-Linked Dystonia Parkinsonism From Its Mimics. Frontiers in Neurology, 9:830, doi: 10.3389/fneur.2018.00830, 2018
X-linked dystonia parkinsonism is a hereditary condition afflicting mostly males, causing twisting motions and contortions of the extremities early in the disease. We developed a questionnaire composed of questions on shuffling of gait, slowness of movement, constant jaw opening and closing and sustained twisting that can help distinguish these patients from other neurologic patients such as Parkinson disease and stroke. We saw a total of 306 subjects and used their responses to validate the questionnaire. The strongest predictor of the diagnosis was shuffling of gait. A score of 6 using the questionnaire and their corresponding weights was considered to be positive with the questionnaire—identifying patients who are most likely to be XDP patients. Identifying these patients can help prioritize which patients need further work-up (i.e. genetic testing) and consult with movement disorder specialists to verify the diagnosis of XDP.
Significance:
The research validates a questionnaire that can distinguish XDP patients from mimics of the disease. Doing so prioritizes resources for these patients.
Link to the article: https://www.frontiersin.org/articles/10.3389/fneur.2018.00830/full
Impact factor: (2017/2018) 3.508
Marysia Tiongco Recto
Department of Pediatrics
College of Medicine
UP Manila
Economic Burden of the Inadequate Management of Allergic Rhinits and Urticaria in Asian Countries Based on the GA2LEN Model. Allergy Asthma Immunol Res. 2018 Forthcoming. Posted online 2018. Pages 1-9
Thirty-five percent of employed individuals in six Asian countries (Hongkong, Malaysia, Philippines, Singapore, Thailand and Vietnam) suffer from allergic rhinitis and urticaria. Approximately ninety percent of them are are insufficiently treated thus affecting their work performance (more work absences and decreased productivity) and thus increasing socioeconomic burden. This study aims to estimate this socioeconomic burden of two important allergic diseases, allergic rhinitis and urticaria in Asia. It also aims to assess the cost savings that adequate allergy management will provide. Clinical experts from the aforementioned countries were involved in the study. They noted that many patients experience these allergic diseases year-round. The estimated indirect cost of allergy treatment due to poor control of disease leading to poor work performance was USD 105.4 billion a year (USD 1,137-2,195/patient/year). Following proper allergy treatment guidelines can lead to an estimated savings of up to USD 104 Billion. The authors then concluded that the socioeconomic impact of poorly controlled allergies in Asia is similar to that in the European Union. The burden may be higher in Asia due to lower wages and year-long exposures to allergens because of the tropical climate. The need for government initiatives to increase awareness of on prevention and treatment of allergies as well as provision of research funding for bigger clinical studies in the Asian population may be needed.
Significance:
Second-generation antihistamines and intranasal corticosteroids are recommended in the treatment of allergic disease such as allergic rhinitis and urticaria. However, at times, these medications affect productivity of patients because of their adverse effects especially sedation. So far, no study has been done to assess the economic burden of inadequately treated allergies in Asia. Thus, the authors from selected Asian countries aimed to assess this economic issue based statistics, literature review and clinical experience similar to what allergists in the European Union and Asia (GA2LEN) did.Furthermore, the authors also explored the potential role of the usual allergy medications in lowering socioeconomic burden of these allergic diseases.
Link to the article: https://e-aair.org/search.php?where=aview&id=10.4168/aair.2018.10.4.370&code=999AIR&vmade=FULL
Impact factor: (2017/2018) 3.809
Dina Grace C. Banguilan and Nathaniel P. Hermosa II
National Institute of Physics
College of Science
UP Diliman
Measuring the orbital angular momentum of light by dynamic polygon apertures. Proc. SPIE 10818, Holography, Diffractive Optics, and Applications VIII, 108180U (8 November 2018); doi: 10.1117/12.2500986
Simulated (left, black and white) and experimental (right, black and orange) diffraction patterns of light with negative (top row) and positive (bottom row) topological charge by different polygon apertures.
It is well-known that light carries information. Idea about its intensity, direction, frequency and polarization can provide information about its source or its state/mode as well as the medium it has propagated through. With these promising properties of light, we can transmit data from one place to another by encoding the data into one of its properties. Another fact which is less widely known is that light can carry an orbital angular momentum (OAM), which is a property of all objects in rotational motion. OAM’s greatest asset is its capability to take infinitely many orthogonal states. Hence, if OAM is measured efficiently, it can provide us additional property to encode data and consequently opens new and interesting physics.
In this article, we were able to engineer a dynamic technique for an efficient measurement of the OAM of light. The idea basically is to pass a light with OAM with our programmable aperture with polygonal shapes (i.e. triangle, square, pentagon, hexagon). The light is diffracted, and it produced patterns which is related to the OAM of light. One of its fascinating applications is on OAM multiplexing technology which offers a way of achieving wireless transmission to support the ever-increasing demand in wireless communication.
Significance:
We were able to contribute with the growing interest in the detection of orbital angular momentum (OAM) of light through diffraction behind polygonal aperture by introducing a dynamic method together with resolving the challenging task of characterizing a light field. By an experimental demonstration of our system, we were able to extract information (i.e. magnitude and sign of the topological charge) about the unknown light. Our method establishes potential speed and accuracy of describing the property of light. OAM can interact with particle and can store data and thus is essential to applications like optical manipulation and communication technology, respectively.
Link to the article: https://doi.org/10.1117/12.2500986
Impact factor: Not yet available
Niña Angelica F. Zambale, Jenny Lou B. Sagisi and Nathaniel P. Hermosa II
National Institute of Physics
College of Science
UP Diliman
Goos-Hänchen shifts due to graphene when intraband conductivity dominates. Optics Communications. 433 (2019), 25-29
Colormaps of maximum physical shift as a function of Fermi level and incident frequency. We have calculated a physical beamshift of up to −13 mm.
Schematic representation of spatial and angular GH shifts. A physical beam with a finite beam extent experiences lateral and angular displacements that deviate from well known descriptions of the laws of reflection and refraction.
A beam of light striking a surface is usually expected to move according to the law of reflection. However in reality, the reflected light actually shifts from where it is expected to emerge. This is known as the Goos-Hänchen shift. The amount of shift strongly depends on certain material properties such as thickness and index of refraction. Measurement of this shift thus can provide a non-destructive way to characterize materials different material properties.
We focus our research on graphene because of its unique optical properties for practical electronic and device applications. The conductivity of graphene in the visible range can be approximated as a constant. At higher beam frequencies (where the “intraband conductivity” dominates), its conductivity increases significantly, reaching up to two orders of magnitude higher than the conductivity in the visible range. On the top of that, the conductivity now depends on several factors which we can control and thus we can modify graphene’s optical and electronic properties at higher frequencies. This can have applications in controllable opto-electronic devices.
We calculated the amount of shift of a THz beam incident on graphene as we vary the incident angle, incident frequency, and Fermi level. These are all controllable factors in an experiment. We locate the physical shift in cases where there is large beamshifts for easy detection. The results can help determine the optical properties of graphene and can be extended to other 2D materials with intraband conductivity.
Signficance
The Goos-Hänchen shift can be used to determine certain properties of material such as thickness and index of refraction, which is helpful for non-invasive material characterization. Determining and controlling of the value of the shift therefore is useful for material applications. The results presented in our paper can aid experimentalists to determine the optimal incident angle and frequency at given experimental parameters for easy detection of the shift.
We also presented the relation of Fermi energy to the amount of shift. This can have major applications in controllable graphene-based opto-electronic devices
Link to the article: https://www.sciencedirect.com/science/article/pii/S0030401818308393
Impact factor: (2017/2018) 1.887
Cecilia Conaco and Chyrene Moncada
Marine Science Institute
College of Science
UP Diliman
Microbial community composition of sediments influenced by intensive mariculture activity. FEMS Microbiology Ecology. 95(2):fiz006. doi:10.1093/femsec/fiz006
Image of a milkfish cage in Guiguiwanen Channel, Bolinao, Pangasinan
Picture of the sediment and sediment-water interface taken from the milkfish farming area of Bolinao. A distinct layer of Beggiatoa are seen as a white mat on top of the dark sulfidic sediments.
In this study, we compared the sediment from a site directly below a fish cage and a site away from a fish cage. We found that wastes from excessive feeding of milkfish in the cages change the chemical properties of the sediment. The sediment had little to no oxygen, and had plenty of sulfides including hydrogen sulfide, which in high amounts is toxic. Too much wasted feed also changed the type of microorganisms living in the sediment. The changes favored the growth of bacteria that like low oxygen and high nutrient environments. These microbes have the potential to be biological indicators when the sediment has very high amounts of nutrients in it and could be used in assessing coastal health. Based on the abundance of some genes, we also found evidence that these microbial communities vary in their capabilities to process or “digest” sulfur and nitrogen compounds. Overall, our findings further confirm the impact of aquaculture on marine sediments. If left unregulated, fish kills will persist in the area and the compounds being produced from bacterial processes may also pose a threat to the health of the fish reared in the cages, and to us consumers.
Significance:
Production of milkfish in sea cages has rapidly expanded in the coastal areas of Bolinao, Philippines since 1995 and has been accompanied by a long history of persistent algal blooms and fish kills. However, no studies have yet been done to characterize the impact of aquaculture on the microbial community at the fish farming site using next generation sequencing technologies. This information would provide a useful tool for assessing and monitoring the impact of the fish farming activities on coastal health.
Link to the article: https://academic.oup.com/femsec/article-abstract/95/2/fiz006/5289376
Impact factor: (2017/2018) 3.495
Jancel Carlo B. Villanueva, Cherry L. Ringor and Chelo S. Pascua
Institute of Environmental Science and Meteorology
College of Science
UP Diliman
Size, structure, and conductivity of plant oil-derived carbon nanospheres synthesized by atmospheric ionization CVD. Materials Chemistry and Physics, 2019, vol. 225, pp. 84–90
Carbon spheres are spherically shaped carbon materials that grow in different sizes ranging from < 10 nm to > 1μm. They have high surface area, high thermal stability, low density and good electrical conductivity, which means that they have potential applications in supercapacitors, electrophoretic deposition, catalyst support materials, lithium ion batteries, and conductive ink. As high-value materials, their production necessitates an innovative approach to green and sustainable nanomaterial synthesis. We have accomplished this through the use of marginalized but locally abundant natural resources as precursors. We used Calophyllum inophyllum (local name Bita-og) seed oil to synthesize conducting carbon nanospheres. In addition, we have optimized the synthesis procedure to control the size of the carbon spheres to nanometer scale. Size-control is important, especially in the nanometer regime, since size influences their properties and therefore, their applications. The electrical properties and diameters of ionized carbon nanosphers obtained from our study indicate potential use as raw materials for the development of inkjet resistors and temperature sensing devices. This work highlights (1) green or eco-friendly material synthesis through the utilization of locally available natural precursors, (2) development of value-added materials from marginalized resources, and (3) design, fabrication and modification of reactor chamber and synthesis procedure to control the size of conducting carbon spheres at nanometer range.
Significance:
Carbon nanospheres have a wide variety of potential applications: in supercapacitors, electrophoretic deposition, catalyst support materials, lithium ion batteries, and conductive ink. This work highlights the synthesis and size-control of conducting carbon nanospheres following the principle of green chemistry, which promotes the use of renewable feedstock in any industrial process. The use of naturally available materials as starting precursors for the production of carbon nanospheres has provided a way to circumvent some of the problems using common commercially available hydrocarbon sources. The utilization of a locally-sourced plant oil as a carbon feed stock provides not just a way to lower the costs of production, but also ensures sustainability.
Link to the article: https://doi.org/10.1016/j.matchemphys.2018.12.062
Impact factor: (2017/2018) 2.210
