**2. Chitosan**

*Chitin and Chitosan - Physicochemical Properties and Industrial Applications*

and antimicrobial activity have attracted interest in medicine, pharmacy, biomedical and health-related applications [1, 3, 4]. Numerous Cts-based materials were produced such as nano and microparticles, gels, sponges, films and membranes [4]. They have created an efficient field of application for drug delivery, wound healing

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**Figure 2.**

**Figure 1.**

*Field of application of Cts.*

and tissue regeneration applications.

*Biopolymer classification: Animal, agro, and protein origins.*

### **2.1 Sources of chitin and chitosan**

Chitin is usually found in nature in seaweeds, protozoa (flagellates, amoebic ciliates, etc.), selenterals, mollusks, arthropods, bacteria, fungi, insects and some plants. The richest sources of chitin are; crab, shrimp, lobster and crayfish shells. Chitin biopolymers of animal origin are mainly found in animals. Chitin is the most considerable polysaccharide on the planet. Due to its strong hydrogen bonds and high crystal property of its cohesive structure forces, chitin is an insoluble substance in normal solvents, including water and organic matter [5]. Cts is abundant in marine or terrestrial animals such as crustaceans, insects, mollusks and fungi [6] without a backbone, such as various insects and marine diatoms. Commercial production of Cts by alkaline hydrolysis by extracting chitin from shrimp shell waste has been carried out by a group scientist [3, 6].

#### **2.2 Chitosan production**

Cts is obtained from chitin. Rouget became aware of Cts in 1859 while conducting experimental activities on deacetylated forms of chitin [7]. Cts is obtained from waste shrimp and crab shells from the seafood industries by chemical methods in industrial processes around the world [4]. Basic structure properties of Cts are related to its molecular weight and degree of deacetylation. The crystallinity of Cts is important in classifying its particle size, moisture and ash content, which is based on its surface morphology properties. The solubility, antibacterial, polycationic character, biocompatibility and bio adhesiveness of Cts are the basis that define the Cts structure and application areas [8, 9].

Chemical modifications of Cts have been extensively described in recent studies. Cts contains the reactive amino (-NH2) and hydroxyl (-OH) groups in its structure and can very easily be converted into new modified forms. The presence of amino groups in the Cts matrix (deacetylation degree) in macromolecular chains indicates that Cts has a polycationic property in acidic aqueous solutions. The protonation of amino groups in the polymer structure seriously affects the structure of macromolecules in solutions, and it is known that the structure behavior may be managed through changing the pH or ionic strength of the solution it is in.

Cts production is carried out by two basic methods, chemically and biologically. Classically, the chemical method is the method in which physical and chemical methods are used together. Chemical method; the isolation of the chitin is carried out by removing other substances in the shell. The procedures for this can be grouped under four main steps:

3.Deproteinization (removal of proteins).

4.Decoloration (removal of pigments). These stages are given in **Figure 3**.

Biological methods are processes that can be examined under several headings. Cell cultures of various organisms such as Mucor rouxii, Phycomyces blakesleeanus are used in the microbial synthesis of Cts. The product obtained is developed by adding Aspergillus niger to the culture medium. Thus, this production mechanism also leads to the deacetylation of the Cts. Cts is obtained at the end of the 96-hour incubation period [10]. As a biological method, the use of proteolytic enzymes such as pepsin, trypsin, protease, proteinase and papain in protein removal can be counted [11]. Today, many other polymers used in industry are produced synthetically. Synthetic polymers have limited biocompatibility and biodegradability compared to Cts, a natural polymer.


Abstract

In this chapter, the calculation of vibrational zero-point energies (ZPEs) of organosilicon compounds is reported. An empirical formula is used. This relationship was determined by relating vibrational zero-point energy to the nature and type of bonds forming the molecule. The calculated vibrational zero-point energies for several organosilicon derivatives belonging to different categories of compounds correlate well with the reported available values. In addition, the comparison of these results with the scaled values obtained using methods of quantum chemistry (AM1, ab initio, and by a similar empirical approach) indicates the reliability of our empirical model to reproduce vibrational zero-point energy of organosilicon compounds.

Keywords: zero-point energy (ZPE), empirical ZPE, organosilicon compounds, theory-experiment correlation


**2. Method**

The preferred reporting items for systematic reviews and meta-analysis (PRISMA) checklist was used to design the study and to report results based on best practices in the field of literature reviews and meta-analyses [42].

#### **2.1 Literature research**

We conducted a literature review in these databases: PsycNet, MedLine, ProQuest, Web of Knowledge, Cochrane, and Psychology and Behavioral Sciences Collection. Search terms used in PsycNet were "panic disorder" OR "panic attack" OR panic AND sleep OR "sleep disorders" OR insomnia OR "nocturnal panic" OR "sleep deprivation." Search terms used in MedLine, Web of Knowledge, and Cochrane were panic OR "panic disorder" AND sleep OR "sleep initiation and maintenance disorders" OR dyssomnia OR "sleep deprivation." Publication date was 1980 (DSM-III year of publication) to May 2016 inclusive.

To retrieve gray literature (i.e., unpublished work or studies that are published outside widely available journals) [43], reference lists of selected articles were searched for potentially eligible articles regarding sleep in PD. The Laval University library was searched for book chapters addressing sleep in PD. Reference lists were screened for articles of interest. Inclusion of ProQuest and Web of Knowledge databases helped retrieve gray literature, as these sources contain theses, symposia, and convention papers, in addition to journal articles.

#### **2.2 Article selection**

The following inclusion criteria were used: (a) studies had to be published in English, French, or Spanish; (b) minimum participant age was 18 years; (c) to ensure population representativeness, studies including participants with comorbidities were accepted if PD was the primary diagnosis for at least one subgroup; (d) studies had to report quantitative group data for at least one sleep variable; (e) data on sleep disturbances had to include means, standard deviations, and group sizes for PD and control groups; (f) prevalence of NPA had to be reported in percentage or number of participants, and total sample size had to be included; (g) data had to be issued from self-report questionnaires, clinician-administered interviews, sleep diaries, polysomnography, or actigraphy; and (h) for subjective and objective sleep data, patients with PD had to be compared to a group of healthy controls (for the prevalence of nocturnal panic, no comparison group was necessary).

Studies that met the following criterion were excluded: (a) studies in which all patients with PD reported a physical disease or one of the following comorbid psychiatric disorders, schizophrenia, bipolar disorder, and alcohol or drug abuse or dependence, and (b) studies in which no data could be grouped using the following procedure:

Studies were classified and grouped on the basis of the measure they reported. For example, all studies reporting results on the Pittsburgh sleep quality index (PSQI) were grouped together, the same was done for the Hamilton rating scale (HAM-D), polysomnography, etc. For articles reporting NPA, grouping was carried out on the basis of the frequency criteria used. For example, all studies reporting the prevalence of patients who had at least one NPA in their lifetime were grouped together, all articles reporting the prevalence of patients having at least one NPA/month were grouped together, etc. Some articles reported data from specific sleep measures or NPA frequency criteria that were not repeated elsewhere.

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**Table 1.**

*Inter-rater agreement.*

*A Meta-Analysis of Sleep Disturbances in Panic Disorder DOI: http://dx.doi.org/10.5772/intechopen.86306*

graphic/actigraphic data, and prevalence of NPA).

additional study were excluded.

**2.3 Data extraction**

**2.4 Inter-rater agreement**

*2.4.1 Article selection*

*2.4.2 Data extraction*

**Study description**

**Self-report data**

**NPA**

**Polysomnographic data**

*Note: NPA = nocturnal panic attack; PD = panic disorder.*

Studies reporting data that could not be grouped with other data from at least one

Once reference retrieval was complete, each of the selected papers was reviewed,

To reduce selection bias, a second trained judge independently rated the eligibility of 30% of the retrieved literature. The results of the two judges' ratings were compared, and cases of disagreement were discussed to reach consensus.

Five raters participated in data extraction. Four of the judges were undergraduate psychology students, and one was a graduate psychology student (AP). A pilot coding was conducted, wherein all judges used the coding manual to rate the same

**Item Percentage inter-rater agreement**

PD group sample size 100.0 Control group sample size 100.0 Mean age 88.2 Gender 73.1 Medication permitted or not 96.2 Percentage of participants taking medication 84.6 Psychometric instrument used to diagnose PD 82.7 Psychometric instrument used to assess sleep 100.0

Sleep variable—PD group 88.9 Sleep variable—control group 88.9

Sleep variable—PD group 100.0 Sleep variable—control group 98.8

Percentage of sample reporting NPA 46.7 NPA frequency criterion 66.7

and data was extracted using a standardized rating form and coding manual. Extracted variables included information about the sample and sampling method, general methodology, and sleep characteristics (self-report sleep data, polysomnoStudies reporting data that could not be grouped with other data from at least one additional study were excluded.